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Volume 14
Issue 7
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Catalysts, Volume 14, Issue 7 (July 2024) – 75 articles

Cover Story (view full-size image): ERI and SSZ-13 were subjected to post-synthetic treatments (depending on the zeolite topology) to create micro/mesoporous materials. The post-synthetic modification of the investigated zeolites varied their catalytic activity in the selective catalytic reduction of NO with ammonia (NH3-SCR-DeNOx). Regarding the Cu-containing ERI, the NO conversion was higher for catalysts with modified supports. For the Cu-containing SSZ-13 catalysts (with post-modified zeolites), a lower NO conversion in NH3-SCR-DeNOx was observed. According to the physico-chemical characterization, the modification of the supports resulted in the presence of different amounts and kinds of copper species (especially isolated Cu2+ and aggregated Cu species) of ERI- and SSZ-13-based samples. View this paper
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17 pages, 2834 KiB  
Communication
A First-Principles Study on the Reaction Mechanisms of Electrochemical CO2 Reduction to C1 and C2 Products on Cu(110)
by Yangyang Xu and Lixin Zhang
Catalysts 2024, 14(7), 468; https://doi.org/10.3390/catal14070468 - 22 Jul 2024
Viewed by 573
Abstract
The mechanism of the electrochemical CO2 reduction reaction on a Cu(110) surface has yet to be fully revealed. In this work, based on first-principles calculations, we investigate the mechanisms of the CO2 reduction reaction to produce C1 (including one C [...] Read more.
The mechanism of the electrochemical CO2 reduction reaction on a Cu(110) surface has yet to be fully revealed. In this work, based on first-principles calculations, we investigate the mechanisms of the CO2 reduction reaction to produce C1 (including one C atom) and C2 (including two C atoms) products on a Cu(110) surface. The results show that CH4 and C2H5OH are the main C1 and C2 products on the Cu(110) surface, respectively. CH4 is produced along the pathway CO2 → COOH* → CO* → CHO* → CH2O* → CH3O* → CH4. C2H5OH is produced via the C-C coupling pathway between CO* and CH2O* intermediates, which is the key reaction step. This is because CO* and CH2O* coupling to CO-CH2O* has the lowest barrier among the CHxO* (x = 0–2) coupling pathways. Therefore, it is the most likely C-C coupling pathway. Further, CO-CH2O* is gradually hydrogenated to C2H5OH along the following pathway: CO-CH2O* → CHO-CH2O* → CHOH-CH2* → CH2OH-CH2* → CH2OH-CH3* → C2H5OH. Full article
(This article belongs to the Section Electrocatalysis)
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Figure 1

Figure 1
<p>Gibbs free energy diagram for CO<sub>2</sub> reduction to CH<sub>4</sub> on the Cu(110) surface. The energy of [* + CO<sub>2</sub>(g) + 4H<sub>2</sub>(g)] is set as a reference. X* represents species X adsorbed on the Cu(110) surface. The optimized adsorption geometries of key intermediates are shown in the insets. Cu: yellow, C: brown, O: red, H: white.</p> Full article ">Figure 2
<p>A schematic potential energy diagram from CO* hydrogenation to CH<sub>3</sub>O* on the Cu(110) surface. The optimized adsorption geometries of the initial states, transition states, and finial states are shown in the insets. Cu: yellow, C: brown, O: red, H: white.</p> Full article ">Figure 3
<p>Schematic potential energy diagrams for (<b>a</b>) two-CO* dimerization, (<b>b</b>) CO* and CHO* coupling, (<b>c</b>) CO* and CH<sub>2</sub>O* coupling, (<b>d</b>) CHO* and CH<sub>2</sub>O* coupling, (<b>e</b>) CHO* and CHO* coupling, and (<b>f</b>) CH<sub>2</sub>O* and CH<sub>2</sub>O* coupling on the Cu(110) surface. The optimized adsorption geometries of initial states, transition states, and finial states are shown in the insets. Cu: yellow, C: brown, O: red, H: white.</p> Full article ">Figure 4
<p>(<b>a</b>) The DOSs of C atoms in the adsorbed intermediates for the CO* and CH<sub>2</sub>O* coupling pathway on the Cu(110) surface. (<b>b</b>) Diagrams of the difference in charge densities of CO-CH<sub>2</sub>O* on the Cu(110) surface by an isosurface of 0.002 eV/Å. Yellow represents an electron-accumulation region and blue represents an electron-loss region. <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>ρ</mi> <mo>=</mo> <mi>ρ</mi> <mfenced separators="|"> <mrow> <msup> <mrow> <mi>X</mi> </mrow> <mrow> <mo>∗</mo> </mrow> </msup> </mrow> </mfenced> <mo>−</mo> <mi>ρ</mi> <mfenced separators="|"> <mrow> <mo>∗</mo> </mrow> </mfenced> <mo>−</mo> <mi>ρ</mi> <mo>(</mo> <mi>X</mi> <mo>)</mo> </mrow> </semantics></math>.</p> Full article ">Figure 5
<p>Gibbs free energy diagram for the production of C<sub>2</sub>H<sub>5</sub>OH on the Cu(110) surface. The optimized adsorption geometries of key intermediates are shown in the insets. Cu: yellow, C: brown, O: red, H: white.</p> Full article ">Figure 6
<p>Gibbs free energy diagrams for CO<sub>2</sub> reduction to (<b>a</b>) CH<sub>4</sub> and (<b>b</b>) C<sub>2</sub>H<sub>5</sub>OH on Cu(110) surface with applied potentials of 0 V and −0.66 V versus RHE.</p> Full article ">Figure 7
<p>The (<b>a</b>) top view and (<b>b</b>) side views of the Cu(110) surface. Cu: yellow.</p> Full article ">
9 pages, 820 KiB  
Article
Synthesis of Propiolic and Butynedioic Acids via Carboxylation of CaC2 by CO2 under Mild Conditions
by Xiao-Min Zhao, Xiaoteng Zang, Yingzhou Lu, Hong Meng and Chunxi Li
Catalysts 2024, 14(7), 467; https://doi.org/10.3390/catal14070467 - 22 Jul 2024
Viewed by 596
Abstract
Carbon dioxide (CO2) is a greenhouse gas, and its resource use is vital for carbon reduction and neutrality. Herein, the nucleophilic addition reaction of calcium carbide (CaC2) to CO2 was studied for the first time to synthesize propiolic [...] Read more.
Carbon dioxide (CO2) is a greenhouse gas, and its resource use is vital for carbon reduction and neutrality. Herein, the nucleophilic addition reaction of calcium carbide (CaC2) to CO2 was studied for the first time to synthesize propiolic and butynedioic acids by using CuI or AgNO3 as catalyst, Na2CO3 as additive, and triphenylphosphine as ligand in the presence/absence of a hydrogen donor. The effects of the experimental conditions and intensification approach on the reaction were investigated. The reactivity of CaC2 is closely associated with its synergistic activation by the catalysts, solvent, and external intensification, such as the ultrasound and mechanical force. Ultrasound helps to promote the reaction by enhancing the interfacial mass transfer of CaC2 particulates. Mechanochemistry can effectively promote the reaction, yielding 29.8% of butynedioic acid and 74.8% of propiolic acid after 2 h ball milling at 150 rpm, arising from the effective micronization and interfacial renewal of calcium carbide. The present study sheds a light on the high-value uses of CO2 and CaC2 and is of reference significance for the nucleophilic reaction of CaC2 with other carbonyl compounds. Full article
(This article belongs to the Special Issue Feature Papers in "Industrial Catalysis" Section)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>The yield of butynedioic acid versus time for thermal reaction (<b>a</b>) and rotation rate of ball mill (<b>b</b>). Reaction conditions: (<b>a</b>) CH<sub>3</sub>CN 10 mL, 1 g CaC<sub>2</sub>, CO<sub>2</sub> 0.6 MPa CaC<sub>2</sub>:CO<sub>2</sub> ≈ 1:6 (mole ratio), 333 K, 300 mL oxygen bomb reactor, magnetic stir; (<b>b</b>) CH<sub>3</sub>CN 15 mL, 0.3 g CaC<sub>2</sub>, CO<sub>2</sub> 0.2 MPa, 0.03 g AgNO<sub>3</sub>, 0.046 g PPh<sub>3</sub>, 0.37 g Na<sub>2</sub>CO<sub>3</sub>, 298 K, 375 g S.S balls, 250 mL jar, planetary ball mill.</p> Full article ">Figure 2
<p><sup>13</sup>CNMR spectra of the product butynedioic acid (<b>a</b>) and propiolic acid (<b>b</b>) using phenolic resin as hydrogen donor.</p> Full article ">
14 pages, 1950 KiB  
Article
One-Pot Phyto-Mediated Synthesis of Fe2O3/Fe3O4 Binary Mixed Nanocomposite Efficiently Applied in Wastewater Remediation by Photo-Fenton Reaction
by Amr A. Essawy, Tamer H. A. Hasanin, Modather. F. Hussein, Emam F. El Agammy and Abd El-Naby I. Essawy
Catalysts 2024, 14(7), 466; https://doi.org/10.3390/catal14070466 - 20 Jul 2024
Cited by 1 | Viewed by 757
Abstract
A binary Fe2O3/Fe3O4 mixed nanocomposite was prepared by phyto-mediated avenue to be suited in the photo-Fenton photodegradation of methylene blue (MB) in the presence of H2O2. XRD and SEM analyses illustrated that [...] Read more.
A binary Fe2O3/Fe3O4 mixed nanocomposite was prepared by phyto-mediated avenue to be suited in the photo-Fenton photodegradation of methylene blue (MB) in the presence of H2O2. XRD and SEM analyses illustrated that Fe2O3 nanoparticles of average crystallite size 8.43 nm were successfully mixed with plate-like aggregates of Fe3O4 with a 15.1 nm average crystallite size. Moreover, SEM images showed a porous morphology for the binary Fe2O3/Fe3O4 mixed nanocomposite that is favorable for a photocatalyst. EDX and elemental mapping showed intense iron and oxygen peaks, confirming composite purity and symmetrical distribution. FTIR analysis displayed the distinct Fe-O assignments. Moreover, the isotherm of the developed nanocomposite showed slit-shaped pores in loose particulates within plate-like aggregates and a mesoporous pore-size distribution. Thermal gravimetric analysis (TGA) indicated the high thermal stability of the prepared Fe2O3/Fe3O4 binary nanocomposite. The optical properties illustrated a narrowing in the band gab (Eg = 2.92 eV) that enabled considerable absorption in the visible region of solar light. Suiting the developed binary Fe2O3/Fe3O4 nanocomposite in the photo-Fenton reaction along with H2O2 supplied higher productivity of active oxidizing species and accordingly a higher degradation efficacy of MB. The solar-driven photodegradation reactions were conducted and the estimated rate constants were 0.002, 0.0047, and 0.0143 min−1 when using the Fe2O3/Fe3O4 nanocomposite, pure H2O2, and the Fe2O3/Fe3O4/H2O2 hybrid catalyst, respectively. Therefore, suiting the developed binary Fe2O3/Fe3O4 nanocomposite and H2O2 in photo-Fenton reaction supplied higher productivity of active oxidizing species and accordingly a higher degradation efficacy of MB. After being subjected to four photo-Fenton degradation cycles, the Fe2O3/Fe3O4 nanocomposite catalyst still functioned admirably. Further evaluation of Fe2O3/Fe3O4 nanocomposite in photocatalytic remediation of contaminated water using a mixture of MB and pyronine Y (PY) dyestuffs revealed substantial dye photodegradation efficiencies. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Figure 1
<p>XRD pattern with Rietveld refinement. (<b>A</b>) FTIR spectrum; (<b>B</b>) TGA profile; (<b>C</b>) of the developed binary Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">Figure 2
<p>SEM image. (<b>A</b>) EDX spectrum; (<b>B</b>) EDS mapping; (<b>C</b>–<b>E</b>) of the developed binary Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">Figure 3
<p>N<sub>2</sub> adsorption–desorption isotherm (<b>A</b>) and pore size distribution (<b>B</b>) of the developed binary Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">Figure 4
<p>UV–Visible electronic spectra of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite (<b>A</b>) and the corresponding plot of (<span class="html-italic">αhυ</span>)<sup>1/2</sup> versus <span class="html-italic">hυ</span> (<b>B</b>).</p> Full article ">Figure 5
<p>Time-dependent variations in absorption spectrum of MB during the solar-driven photo-Fenton catalytic degradation in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> hybrid catalyst (<b>A</b>) and the first order photodegradation kinetics for detoxification of MB using Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>, H<sub>2</sub>O<sub>2</sub>, and Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> catalysts (<b>B</b>).</p> Full article ">Figure 6
<p>Comparison of MB photodegradation in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>, H<sub>2</sub>O<sub>2</sub>, and Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> catalysts. (<b>A</b>) The durability study of the developed heterostructure during consecutive cycles of photo-Fenton processes (<b>B</b>).</p> Full article ">Figure 7
<p>The absorption spectra of a mixture of MB and PY dyestuff mixture before and after solar-driven photo-Fenton catalytic degradation in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> hybrid catalyst. (<b>A</b>) Comparison of the photodegradation efficiency of MB and PY in their mixture in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> hybrid catalyst (<b>B</b>).</p> Full article ">Figure 8
<p>A plausible mechanism for the solar-driven photo-Fenton degradation of MB in presence of biosynthesized Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">
16 pages, 3291 KiB  
Article
Effect of Support Functionalization on Catalytic Direct Hydrogenation and Catalytic Transfer Hydrogenation of Muconic Acid to Adipic Acid
by Elisa Zanella, Stefano Franchi, Narmin Jabbarli, Ilaria Barlocco, Marta Stucchi and Carlo Pirola
Catalysts 2024, 14(7), 465; https://doi.org/10.3390/catal14070465 - 19 Jul 2024
Viewed by 534
Abstract
The liquid-phase hydrogenation of muconic acid (MA) to produce bio-adipic acid (AdA) is a prominent environmentally friendly chemical process, that can be achieved through two distinct methodologies: catalytic direct hydrogenation using molecular hydrogen (H2), or catalytic transfer hydrogenation utilizing a hydrogen [...] Read more.
The liquid-phase hydrogenation of muconic acid (MA) to produce bio-adipic acid (AdA) is a prominent environmentally friendly chemical process, that can be achieved through two distinct methodologies: catalytic direct hydrogenation using molecular hydrogen (H2), or catalytic transfer hydrogenation utilizing a hydrogen donor. In this study, both approaches were explored, with formic acid (FA) selected as the hydrogen source for the latter method. Palladium-based catalysts were chosen for these processes. Metal’s nanoparticles (NPs) were supported on high-temperature heat-treated carbon nanofibers (HHT-CNFs) due to their known ability to enhance the stability of this metal catalyst. To assess the impact of support functionalization on catalyst stability, the HHT-CNFs were further functionalized with phosphorus and oxygen to obtain HHT-P and HHT-O, respectively. In the hydrogenation reaction, catalysts supported on functionalized supports exhibited higher catalytic activity and stability compared to Pd/HHT, reaching an AdA yield of about 80% in less than 2 h in batch reactor. The hydrogen-transfer process also yielded promising results, particularly with the 1%Pd/HHT-P catalyst. This work highlights the efficacy of support functionalization in improving catalyst performance, particularly when formic acid is used as a safer and more cost-effective hydrogen donor in the hydrogen-transfer process. Full article
(This article belongs to the Section Catalytic Materials)
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Figure 1
<p>Reaction scheme for AdA production starting from different substrates: MA (<b>left</b>) and Na-Muc (<b>right</b>).</p> Full article ">Figure 2
<p>Initial activity (h<sup>−1</sup>) of the three different catalysts for the CDH process calculated after 5 min of reaction using the Equation (5).</p> Full article ">Figure 3
<p>Comparison of the reaction courses for the three different catalysts in the catalytic direct hydrogenation: (<b>a</b>) 1%Pd@HHT, (<b>b</b>) 1%Pd@HHT-O, (<b>c</b>) 1%Pd@HHT-P. Reaction conditions: MA concentration 0.05 M, temperature 70 °C, 3 bar pressure of H<sub>2</sub>, metal/substrate molar ratio 1/500, 1200 rpm.</p> Full article ">Figure 4
<p>AdA Yield monitored along time in the catalytic direct hydrogenation of MA. Reaction conditions: MA concentration 0.05 M, temperature 70 °C, 3 bar pressure of H<sub>2</sub>, metal/substrate molar ratio 1/500, 1200 rpm.</p> Full article ">Figure 5
<p>(<b>a</b>) MA conversion and (<b>b</b>) Yield of AdA after 120 min during recycling tests in the catalytic direct hydrogenation of MA. Reaction conditions: MA concentration 0.05 M, temperature 70 °C, 3 bar pressure of H<sub>2</sub>, metal/substrate molar ratio 1/500, 1200 rpm.</p> Full article ">Figure 6
<p>Comparison of the reaction courses for the three different catalysts in the catalytic transfer hydrogenation: (<b>a</b>) 1%Pd@HHT, (<b>b</b>) 1%Pd@HHT-O, (<b>c</b>) 1%Pd@HHT-P. Reaction conditions: MA concentration 0.005 M, metal/substrate molar ratio 1/65, temperature 70 °C, pressure of N<sub>2</sub> 3 bar, MA/FA ratio 1/10, 1200 rpm.</p> Full article ">Figure 7
<p>Study of the influence of the metal/substrate ratio: 1/65, 1/100 and 1/125 in the catalytic transfer hydrogenation: (<b>a</b>) MA conversion and (<b>b</b>) AdA Yield monitored along time. Reaction conditions: MA concentration 0.005 M, temperature 70 °C, pressure of N<sub>2</sub> 3 bar, MA/FA ratio 1/10, 1200 rpm.</p> Full article ">Figure 8
<p>Study of the influence of the temperature. (<b>a</b>) MA conversion and (<b>b</b>) AdA Yield monitored along time. Reaction conditions: MA concentration 0.005 M, metal substrate molar ratio 1/100, pressure of N<sub>2</sub> 3 bar, MA/FA ratio 1/10, 1200 rpm.</p> Full article ">Figure 9
<p>Representative HR-STEM images of. (<b>a</b>,<b>b</b>) 1wt%Pd@HHT, (<b>c</b>,<b>d</b>) 1wt%Pd@P-HHT and (<b>e</b>,<b>f</b>) 1wt%Pd@O-HHT.</p> Full article ">
15 pages, 5759 KiB  
Article
Facile Preparation of Attapulgite-Supported Ag-AgCl Composite Photocatalysts for Enhanced Degradation of Tetracycline
by Xiaojie Zhang, Huiqin Wang and Chenlong Yan
Catalysts 2024, 14(7), 464; https://doi.org/10.3390/catal14070464 - 19 Jul 2024
Viewed by 491
Abstract
In this study, Ag-AgCl/attapulgite (Ag-AgCl/ATP) composites were synthesized via a direct precipitation method using ATP nanorods as a catalyst supporter. ATP nanorods helped to increase the dispersion of Ag-AgCl particles and broaden the light absorption spectrum, which would also help to increase the [...] Read more.
In this study, Ag-AgCl/attapulgite (Ag-AgCl/ATP) composites were synthesized via a direct precipitation method using ATP nanorods as a catalyst supporter. ATP nanorods helped to increase the dispersion of Ag-AgCl particles and broaden the light absorption spectrum, which would also help to increase the active site of the catalyst to promote the degradation of tetracycline (TC). The photocatalytic activity of the Ag-AgCl/ATP composites was evaluated through the degradation of TC, identifying the loading amount of Ag-AgCl, the concentration of TC, and the reaction temperature as critical factors influencing activity. Specifically, the optimal conditions were observed when the loading of Ag-AgCl was 75%, resulting in a photocatalytic degradation efficiency of 77.65%. Furthermore, the highest degradation efficiency (85.01%) was achieved with a TC concentration of 20 mg/L at 20 °C. Radical trapping experiments suggested that the superoxide anion radical (·O2−) was the primary active species in the degradation process, although hydroxyl radicals (·OH) and holes (h+) also contributed. Reusability tests confirmed that the Ag-AgCl/ATP composites exhibited excellent stability and could be effectively reused. Full article
(This article belongs to the Special Issue Mineral-Based Composite Catalytic Materials)
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Figure 1
<p>XRD patterns of ATP, AgCl, AgCl/ATP and Ag-AgCl/ATP.</p> Full article ">Figure 2
<p>SEM of attapulgite (<b>A</b>), AgCl (<b>B</b>), Ag-AgCl/ATP (<b>C</b>), TEM images of attapulgite (<b>D</b>), AgCl (<b>E</b>), Ag-AgCl/ATP (<b>F</b>).</p> Full article ">Figure 3
<p>Elemental mapping results of 75%-Ag-AgCl/ATP (<b>A</b>–<b>G</b>), Ag (<b>D</b>), O (<b>E</b>), Si (<b>F</b>), Cl (<b>G</b>).</p> Full article ">Figure 4
<p>FT-IR spectra of ATP, Ag-AgCl and Ag-AgCl/ATP photocatalysts.</p> Full article ">Figure 5
<p>(<b>A</b>) XPS spectra of survey scan of 75% Ag-AgCl/ATP; High-resolution XPS spectra of (<b>B</b>) O 1s, (<b>C</b>) Si 2p, (<b>D</b>) AgMN1, (<b>E</b>) Cl 2p.</p> Full article ">Figure 6
<p>DRS pattern of Ag-AgCl/ATP, ATP and AgCl (<b>a</b>). Band gap spectra of as-prepared samples (<b>b</b>); VB-XPS of ATP (<b>c</b>) and AgCl (<b>d</b>).</p> Full article ">Figure 7
<p>(<b>a</b>) Photocurrent intensity test for all prepared samples; (<b>b</b>) impedance test (EIS); (<b>c</b>) linear sweep voltammetry (LSV).</p> Full article ">Figure 8
<p>(<b>A</b>) Different loading amounts of Ag-AgCl/ATP; (<b>B</b>) optimal Ag-AgCl/ATP degradation of different concentrations of TC; (<b>C</b>) degradation efficiency of different concentrations of TC; (<b>D</b>) quasi-first kinetic curve, the trend of ln(<span class="html-italic">C</span><sub>0</sub>/<span class="html-italic">C</span>) with time under different starting concentrations.</p> Full article ">Figure 9
<p>(<b>A</b>) The linear relationship between the reciprocal of the pseudo-first kinetic rate and the initial concentration of TC; (<b>B</b>) optimal Ag-AgCl/ATP degradation of TC at different temperatures; (<b>C</b>) Ag-AgCl/ATP cycle degradation of TC; (<b>D</b>) Ag-AgCl/ATP photocatalytic degradation of TC capture experiment.</p> Full article ">Figure 10
<p>Schematic representation for photocatalytic degradation of TC using Ag-AgCl/ATP composites.</p> Full article ">
15 pages, 2536 KiB  
Article
α-Alkylation of Aliphatic Ketones with Alcohols: Base Type as an Influential Descriptor
by Rasika Mane, Li Hui, Ander Centeno-Pedrazo, Alexandre Goguet, Nancy Artioli and Haresh Manyar
Catalysts 2024, 14(7), 463; https://doi.org/10.3390/catal14070463 - 19 Jul 2024
Viewed by 495
Abstract
Current global challenges associated with energy security and climate emergency, caused by the combustion of fossil fuels (e.g., jet fuel and diesel), necessitate the accelerated development and deployment of sustainable fuels derived from renewable biomass-based chemical feedstocks. This study focuses on the production [...] Read more.
Current global challenges associated with energy security and climate emergency, caused by the combustion of fossil fuels (e.g., jet fuel and diesel), necessitate the accelerated development and deployment of sustainable fuels derived from renewable biomass-based chemical feedstocks. This study focuses on the production of long-chain (straight and branched) ketones by direct α-alkylation of short chain ketones using both homogenous and solid base catalysts in water. Thus, produced long-chain ketones are fuel precursors and can subsequently be hydrogenated to long-chain alkanes suitable for blending in aviation and liquid transportation fuels. Herein, we report a thorough investigation of the catalytic activity of Pd in combination with, (i) homogenous and solid base additives; (ii) screening of different supports using NaOH as a base additive, and (iii) a comparative study of the Ni and Pd metals supported on layered double oxides (LDOs) in α-alkylation of 2-butanone with 1-propanol as an exemplar process. Among these systems, 5%Pd/BaSO4 with NaOH as a base showed the best results, giving 94% 2-butanone conversion and 84% selectivity to alkylated ketones. These results demonstrated that both metal and base sites are necessary for the selective conversion of 2-butanone to alkylated ketones. Additionally, amongst the solid base additives, Pd/C with 5% Ba/hydrotalcite showed the best result with 51% 2-butanone conversion and 36% selectivity to the alkylated ketones. Further, the screening of heterogenous acid-base catalysts 2.5%Ni/Ba1.2Mg3Al1 exhibited an adequate catalytic activity (21%) and ketone selectivity (47%). Full article
(This article belongs to the Section Catalysis for Sustainable Energy)
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Figure 1
<p>X-ray diffraction patterns of: (<b>A</b>) 5%Pd supported LDO; (<b>B</b>) Ni dopped and supported LDO.</p> Full article ">Figure 2
<p>α-alkylation of 2-butanone with 1-propanol over different LDOs catalysts. Reaction conditions: 2-butanone, 0.02 mol; 1-propanol, 0.04 mol, catalyst, 0.4 g; deionized water, 60 mL; time, 22 h; temperature, 180 °C.</p> Full article ">Figure 3
<p>α-alkylation of 2-butanone with 1-propanol over 5%Pd and 5%Ni-supported LDOs without an added base. Reaction conditions: 2-butanone, 0.02 mol; 1-propanol, 0.04 mol; catalyst, 0.4 g; deionized water, 60 mL; time, 22 h; temperature, 180 °C.</p> Full article ">Figure 4
<p>Influence of Ni loading on 2-butanone conversion and product selectivity in α-alkylation of 2-butanone and 1-propanol. Reaction conditions: 2-butanone, 0.02 mol; 1-propanol, 0.04 mol, catalyst, 0.4 g; deionized water, 60 mL; time, 22 h; temperature, 180 °C.</p> Full article ">Scheme 1
<p>Metal- and base-catalyzed α-alkylation of butanone by 1-propanol with borrowed hydrogen methodology.</p> Full article ">Scheme 2
<p>Series and parallel reactions during α-alkylation of butanone with 1-propanol.</p> Full article ">
17 pages, 3891 KiB  
Review
Mn-Based Catalysts in the Selective Reduction of NOx with CO: Current Status, Existing Challenges, and Future Perspectives
by Dianxing Lian, Mohaoyang Chen, Huanli Wang, Chenxi Li, Botao Liu, Guiyao Dai, Shujun Hou, Yuxi Liu and Yongjun Ji
Catalysts 2024, 14(7), 462; https://doi.org/10.3390/catal14070462 - 18 Jul 2024
Viewed by 699
Abstract
The technology for the selective catalytic reduction of NOx by CO (CO-SCR) has the capability to simultaneously eliminate CO and NOx from industrial flue gas and automobile exhaust, thus making it a promising denitrification method. The advancement of cost-effective and high-performing [...] Read more.
The technology for the selective catalytic reduction of NOx by CO (CO-SCR) has the capability to simultaneously eliminate CO and NOx from industrial flue gas and automobile exhaust, thus making it a promising denitrification method. The advancement of cost-effective and high-performing catalysts is crucial for the commercialization of this technology. Mn-based catalysts demonstrate enhanced catalytic efficiency under conditions of low temperature and low oxygen content when compared to other transition metal-based catalysts, indicating significant potential for practical applications. This review outlines the diverse Mn-based catalysts, including bulk or supported MnOx catalysts, bulk or supported Mn-based composite oxide catalysts, and the use of MnOx as dopants. Subsequently, the synthesis methods and catalytic mechanism employed by Mn-based catalysts are presented. The following section examines the impact of O2, H2O, and SO2 on the catalytic performance. Finally, the potential and implications of this reaction are deliberated. This work aims to offer theoretical guidance for the rational design of highly efficient Mn-based catalysts in the CO-SCR reaction for industrial applications. Full article
(This article belongs to the Special Issue Catalytic Energy Conversion and Catalytic Environmental Purification)
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<p>An overview of Mn-based catalysts.</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic illustration of the proposed mechanism for the catalytic oxidation of CO over Cu−Mn catalysts [<a href="#B29-catalysts-14-00462" class="html-bibr">29</a>]; (<b>b</b>) proposed reaction mechanism for NO reduction by CO over CO−CuMnAl catalyst [<a href="#B30-catalysts-14-00462" class="html-bibr">30</a>]; (<b>c</b>) NO conversion curves of OMS−2 prepared by Co doping method [<a href="#B32-catalysts-14-00462" class="html-bibr">32</a>]; (<b>d</b>) schematic illustration of the proposed mechanism for the catalytic CO-SCR over Cu<sub>x</sub>Mn<sub>3−x</sub>O<sub>4</sub> catalysts [<a href="#B33-catalysts-14-00462" class="html-bibr">33</a>].</p> Full article ">Figure 3
<p>(<b>a</b>) Schematic illustration of proposed CO-SCR reaction mechanism on Mn<sub>0.3</sub>Co<sub>2.7</sub>O<sub>4</sub> [<a href="#B46-catalysts-14-00462" class="html-bibr">46</a>]; (<b>b</b>) schematic illustration of proposed CO-SCR reaction mechanism on Mn−CeO<sub>2</sub>@Co<sub>3</sub>O<sub>4</sub> [<a href="#B38-catalysts-14-00462" class="html-bibr">38</a>].</p> Full article ">Figure 4
<p>(<b>a</b>) Reaction mechanism on α-MnO<sub>2</sub> nanorod catalyst [<a href="#B24-catalysts-14-00462" class="html-bibr">24</a>]; (<b>b</b>) reaction mechanism on MnO<sub>x</sub>/TiO<sub>2</sub> catalyst [<a href="#B25-catalysts-14-00462" class="html-bibr">25</a>] (<b>c</b>) reaction mechanism on LaMnO<sub>3</sub> catalyst [<a href="#B58-catalysts-14-00462" class="html-bibr">58</a>].</p> Full article ">Figure 5
<p>(<b>a</b>) N<sub>2</sub> and NH<sub>3</sub> selectivity of CuMnO<sub>2</sub>/SSM sample in the CO-SCR test under the conditions of 5% water, 1000 ppm NO, and 2000 ppm CO [<a href="#B72-catalysts-14-00462" class="html-bibr">72</a>]; (<b>b</b>) effect of H<sub>2</sub>O on NO conversion on Mn-CeO<sub>2</sub>@Co<sub>3</sub>O<sub>4</sub> catalyst activity at 200 °C [<a href="#B38-catalysts-14-00462" class="html-bibr">38</a>]; (<b>c</b>) sulfur resistance stability test of OMS-2 and Sb<sub>0.2</sub>-OMS-2 [<a href="#B42-catalysts-14-00462" class="html-bibr">42</a>]; (<b>d</b>) influence of SO<sub>2</sub> on Ho<sub>0.05</sub>-OMS-2 catalyst activity. Reaction conditions: NO = 0.05%, CO = 0.05%, O<sub>2</sub> = 2%, SO<sub>2</sub> = 0.02%, N<sub>2</sub> = balance, and GHSV = 15,000 h<sup>−1</sup> [<a href="#B43-catalysts-14-00462" class="html-bibr">43</a>].</p> Full article ">
7 pages, 1089 KiB  
Article
Methanol to Aromatics on Hybrid Structure Zeolite Catalysts
by Maria V. Magomedova, Ekaterina G. Galanova, Anastasia V. Starozhitskaya, Mikhail I. Afokin, David V. Matevosyan, Sergey V. Egazaryants, Dmitry E. Tsaplin and Anton L. Maximov
Catalysts 2024, 14(7), 461; https://doi.org/10.3390/catal14070461 - 18 Jul 2024
Viewed by 705
Abstract
A study on the reaction of methanol to aromatic hydrocarbons using catalysts based on hybrid zeolites MFI-MEL, MFI-MTW, and MFI-MCM-41 at a temperature of 340 °C and a pressure of 10.0 MPa was carried out. It is shown that in the synthesis of [...] Read more.
A study on the reaction of methanol to aromatic hydrocarbons using catalysts based on hybrid zeolites MFI-MEL, MFI-MTW, and MFI-MCM-41 at a temperature of 340 °C and a pressure of 10.0 MPa was carried out. It is shown that in the synthesis of hydrocarbons under pressure, the activity of the studied samples is similar and does not have a linear correlation with their total acidity. It was found that the catalyst’s activity is primarily determined by the rate of the initial methanol conversion reaction, which is related to the volume of micropores—more micropores lead to higher activity. Additionally, increasing the volume of mesopores results in the formation of heavier aromatic compounds, specifically C10–C11. Full article
(This article belongs to the Special Issue Microporous and Mesoporous Materials for Catalytic Applications)
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<p>(<b>a</b>) Methanol conversion on hybrid zeolite catalysts. (<b>b</b>) Dependence of methanol conversion on specified contact time. T = 340 °C, P = 10.0 MPa.</p> Full article ">Figure 2
<p>Distribution of individual compounds in methanol conversion on hybrid zeolite catalysts. (<b>a</b>) gaseous hydrocarbons C<sub>1</sub>–C<sub>4</sub>; (<b>b</b>) liquid hydrocarbons C<sub>5</sub>–C<sub>11</sub>.</p> Full article ">Figure 3
<p>Distribution of individual aromatic compounds in methanol conversion on hybrid zeolite catalysts. Green dotted line: interpolation for MFI/Al<sub>2</sub>O<sub>3</sub> and MFI-MEL/Al<sub>2</sub>O<sub>3</sub>, grey dotted line: interpolation for MFI-MCM-41/Al<sub>2</sub>O<sub>3</sub>.</p> Full article ">
4 pages, 156 KiB  
Editorial
Catalysis on Zeolites and Zeolite-like Materials II
by Wladimir Reschetilowski
Catalysts 2024, 14(7), 460; https://doi.org/10.3390/catal14070460 - 17 Jul 2024
Viewed by 432
Abstract
This Special Issue is a continuation of the previous successful Special Issue, “Catalysis on Zeolites and Zeolite-Like Materials”, which presented the latest developments and advances in the synthesis, characterization, and application of zeolites and zeolite-like materials as catalysts by renowned scientists [...] Full article
(This article belongs to the Special Issue Catalysis on Zeolites and Zeolite-Like Materials II)
3 pages, 163 KiB  
Editorial
State of the Art in Molecular Catalysis in Europe
by Carl Redshaw
Catalysts 2024, 14(7), 459; https://doi.org/10.3390/catal14070459 - 16 Jul 2024
Viewed by 495
Abstract
In this editorial, I would like to provide an overview of the eleven contributions to the Special Issue entitled “State of the Art in Molecular Catalysis in Europe”, which is part of the Organic and Polymer Chemistry Section of Catalysts [...] Full article
(This article belongs to the Special Issue State of the Art in Molecular Catalysis in Europe)
19 pages, 1804 KiB  
Review
The Hydrogen Spillover Effect—A Misunderstanding Study II: Single Oxide and Zeolite Supports
by Mohammed M. Bettahar
Catalysts 2024, 14(7), 458; https://doi.org/10.3390/catal14070458 - 16 Jul 2024
Viewed by 609
Abstract
This investigation confirms that the existence of the hydrogen spillover effect (HSPE) in the case of metal catalysts supported on non-reducible monoxides or zeolites is based on a strong corpus of experimental studies, enlarging and deepening previous statements. The structure of hydrogen spillover [...] Read more.
This investigation confirms that the existence of the hydrogen spillover effect (HSPE) in the case of metal catalysts supported on non-reducible monoxides or zeolites is based on a strong corpus of experimental studies, enlarging and deepening previous statements. The structure of hydrogen spillover consists of H/OH pairs conjugated with Mm+/Op− pairs (p = 1 or 2). It is formed by dehydroxylation followed by OH/OH exchange or by the hydrogenation of conjugated pairs. Such a structure imposes the following chemical processes: (i) hydrogenations take place over OH Brönsted acid sites (BAS); (ii) they are excluded over Mm+/Op− Lewis acid sites (LASs), which are deactivating or dehydrogenating; (iii) surface diffusion of hydrogen spillover proceeds through the migration of H/H pairs from LASs to LASs; (iv) the diffusion rates are determined by the oxide supports’ basicity; and (v) H/D exchange is proof of the existence of hydrogen spillover. The nature of hydrogen spillover (radical/ionic) depends on the polarity of the H/OH pairs, which in turn, is determined by the basicity of the support. Our concept of conjugated active sites is a good descriptor of the reaction paths at the molecular level. The view of LASs bringing about additional activity to BAS is not pertinent. Full article
(This article belongs to the Special Issue Feature Papers in "Industrial Catalysis" Section)
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Scheme 1
<p>Proposed H spillover pathways in Pt/HA (LTA) based on DFT calculations. (<b>a</b>) At the Pt<sub>6</sub>–zeolite interface, H<sub>2</sub> is dissociated at the Pt<sub>6</sub> surface (step (i)) and then spilled over to the zeolite surface (step (ii)). (<b>b</b>) When H diffuses over the interior domain of the “defect-free” zeolite framework, H migrates in the form of an H radical (step (iii-1). (<b>c</b>) When the zeolite framework contains LASs, the H atoms migrate in the form of an H<sup>+</sup>/e<sup>−</sup> charge pair. (<b>d</b>) At the zeolite external surface, the LASs serve as catalytic active sites, and the LASs bind the organic molecule (such as benzene) at which the spiltover H<sup>+</sup>/e<sup>−</sup> pair is recombined and transferred to the benzene, yielding C<sub>6</sub>H<sub>7</sub><sup>•</sup> (step (iv)). Dashed squares represent Brönsted and Lewis acid centers. Reprinted from [<a href="#B19-catalysts-14-00458" class="html-bibr">19</a>] with permission from Springer Nature 2022.</p> Full article ">Scheme 2
<p>Proposition of the mechanism of hydrogen spillover formation and propagation for single oxide and zeolite supports.</p> Full article ">Scheme 3
<p>Proposition of the mechanism of a hydrogenation reaction over a H/OH site for single oxide and zeolite supports.</p> Full article ">Scheme 4
<p>Mechanism of diffusion of hydrogen spillover over single oxide and acidic zeolite supports and H/D exchange.</p> Full article ">
19 pages, 4209 KiB  
Article
Post-Synthetically Treated ERI and SSZ-13 Zeolites Modified with Copper as Catalysts for NH3-SCR-DeNOx
by Alejandro Mollá Robles, Gabriele Deplano, Kinga Góra-Marek, Marek Rotko, Anna Wach, Muhammad Fernadi Lukman, Marko Bertmer, Matteo Signorile, Silvia Bordiga, Andreas Pöppl, Roger Gläser and Magdalena Jabłońska
Catalysts 2024, 14(7), 457; https://doi.org/10.3390/catal14070457 - 16 Jul 2024
Viewed by 761
Abstract
ERI and SSZ-13 were subjected to post-synthetic treatments (depending on the zeolite topology) to create micro-/mesoporous materials. The results in terms of NH3-SCR-DeNOx show that the applied treatments improved the catalytic activity of the Cu-containing ERI-based materials; however, the NO [...] Read more.
ERI and SSZ-13 were subjected to post-synthetic treatments (depending on the zeolite topology) to create micro-/mesoporous materials. The results in terms of NH3-SCR-DeNOx show that the applied treatments improved the catalytic activity of the Cu-containing ERI-based materials; however, the NO conversion did not vary for the different materials treated with NaOH or NaOH/HNO3. For the micro-/mesoporous Cu-containing SSZ-13, a lower NO conversion in NH3-SCR-DeNOx was observed. Thus, our findings challenge the current paradigm of enhanced activity of micro-/mesoporous catalysts in NH3-SCR-DeNOx. The modification of the supports results in the presence of different amounts and kinds of copper species (especially isolated Cu2+ and aggregated Cu species) in the case of ERI- and SSZ-13-based samples. The present copper species further differentiate the formation of reactive reaction intermediates. Our studies show that besides the μ-η2,η2-peroxo dicopper(II) complexes (verified by in situ DR UV-Vis spectroscopy), copper nitrates (evidenced by in situ FT-IR spectroscopy) also act as reactive intermediates in these catalytic systems. Full article
(This article belongs to the Section Catalytic Materials)
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<p>XRD patterns of the (<b>a</b>) ERI and (<b>b</b>) SSZ-13 samples and their Cu-containing forms (sample labels as in <a href="#catalysts-14-00457-t002" class="html-table">Table 2</a>).</p> Full article ">Figure 2
<p>(<b>a</b>,<b>b</b>) N<sub>2</sub> sorption isotherms collected at −196 °C and (<b>c</b>,<b>d</b>) BJH pore width distribution of the ERI and SSZ-13 samples, and their Cu-containing forms; (<b>a</b>,<b>c</b>) and (<b>b</b>,<b>d</b>) sample labels are identical.</p> Full article ">Figure 3
<p>(<b>a</b>,<b>b</b>) <sup>29</sup>Si and (<b>c</b>,<b>d</b>) <sup>27</sup>Al NMR spectra of Cu-containing ERI and Cu-containing SSZ-13 samples; * indicates spinning sidebands.</p> Full article ">Figure 4
<p>(<b>a</b>) H<sub>2</sub>-TPR profiles and (<b>b</b>) DR UV-Vis spectra of Cu-containing ERI and SSZ-13 samples; (<b>a</b>) and (<b>b</b>) sample labels are identical.</p> Full article ">Figure 5
<p>Experimental and simulated CW-EPR spectra of dehydrated (<b>a</b>) Cu-containing ERI and (<b>b</b>) SSZ-13 samples at the X-band, including the spectral simulation that adds the contribution of their respective species, (<b>c</b>) XANES spectra, and (<b>d</b>) EXAFS Fourier transforms of the Cu-containing zeolite samples compared with copper references; (<b>c</b>) and (<b>d</b>) sample labels are identical.</p> Full article ">Figure 6
<p>Results of the TPIE experiment obtained for (<b>a</b>) Cu-ERI and (<b>b</b>) Cu-SSZ-13.</p> Full article ">Figure 7
<p>NO conversion of the Cu-containing ERI, SSZ-13, and ZSM-5 samples: (<b>a</b>,<b>c</b>) without H<sub>2</sub>O in the feed, and (<b>b</b>,<b>d</b>) in the presence of H<sub>2</sub>O in the feed. Reaction conditions: m<sub>K</sub> = 0.1 g, <span class="html-italic">c</span>(NO) = 0.05 vol.%, <span class="html-italic">c</span>(NH<sub>3</sub>) = 0.0575 vol.%, <span class="html-italic">c</span>(O<sub>2</sub>) = 4 vol.%, (<span class="html-italic">c</span>(H<sub>2</sub>O) = 5 vol.% when used), He balance, F<sub>TOT</sub> = 120 ml min<sup>−1</sup>, GHSV = 30,000 h<sup>−1</sup>.</p> Full article ">Figure 8
<p>In situ FT-IR spectra of (<b>a</b>,<b>b</b>) Cu-containing ERI and (<b>c</b>,<b>d</b>) Cu-containing SSZ-13 samples, recorded during NH<sub>3</sub>-SCR-DeNO<span class="html-italic"><sub>x</sub></span> at 125 °C. Reaction conditions: m<sub>K</sub> = 0.1 g, <span class="html-italic">c</span>(NO) = 0.1 vol.%, <span class="html-italic">c</span>(NH<sub>3</sub>) = 0.1 vol.%, <span class="html-italic">c</span>(O<sub>2</sub>) = 10 vol.%, He balance, F<sub>TOT</sub> = 120 ml min<sup>−1</sup>.</p> Full article ">Figure 8 Cont.
<p>In situ FT-IR spectra of (<b>a</b>,<b>b</b>) Cu-containing ERI and (<b>c</b>,<b>d</b>) Cu-containing SSZ-13 samples, recorded during NH<sub>3</sub>-SCR-DeNO<span class="html-italic"><sub>x</sub></span> at 125 °C. Reaction conditions: m<sub>K</sub> = 0.1 g, <span class="html-italic">c</span>(NO) = 0.1 vol.%, <span class="html-italic">c</span>(NH<sub>3</sub>) = 0.1 vol.%, <span class="html-italic">c</span>(O<sub>2</sub>) = 10 vol.%, He balance, F<sub>TOT</sub> = 120 ml min<sup>−1</sup>.</p> Full article ">Figure 9
<p>In situ DR UV-Vis DR spectrum of (<b>a</b>,<b>b</b>) Cu-containing ERI and (<b>c</b>,<b>d</b>) Cu-containing SSZ-13 samples during NH<sub>3</sub>-SCR-DeNO<span class="html-italic"><sub>x</sub></span> at different temperatures. Reaction conditions: m<sub>K</sub> = 0.1 g, <span class="html-italic">c</span>(NO) = 0.1 vol.-%, <span class="html-italic">c</span>(NH<sub>3</sub>) = 0.1 vol.-%, <span class="html-italic">c</span>(O<sub>2</sub>) = 10 vol.-%, He balance, F<sub>TOT</sub> = 120 ml min<sup>−1</sup>; (<b>a</b>–<b>d</b>) sample labels are identical.</p> Full article ">
13 pages, 3466 KiB  
Article
Supported Inverse MnOx/Pt Catalysts Facilitate Reverse Water Gas Shift Reaction
by Wenli Bi, Ruoyu Zhang, Qingfeng Ge and Xinli Zhu
Catalysts 2024, 14(7), 456; https://doi.org/10.3390/catal14070456 - 16 Jul 2024
Viewed by 595
Abstract
Catalytic conversion of CO2 to CO via the reverse water gas shift (RWGS) reaction has been identified as a promising approach for CO2 utilization and mitigation of CO2 emissions. Bare Pt shows low activity for the RWGS reaction due to [...] Read more.
Catalytic conversion of CO2 to CO via the reverse water gas shift (RWGS) reaction has been identified as a promising approach for CO2 utilization and mitigation of CO2 emissions. Bare Pt shows low activity for the RWGS reaction due to its low oxophilicity, with few research works having concentrated on the inverse metal oxide/Pt catalyst for the RWGS reaction. In this work, MnOx was deposited on the Pt surface over a SiO2 support to prepare the MnOx/Pt inverse catalyst via a co-impregnation method. Addition of 0.5 wt% Mn to 1 wt% Pt/SiO2 improved the intrinsic reaction rate and turnover frequency at 400 °C by two and twelve times, respectively. Characterizations indicate that MnOx partially encapsulates the surface of the Pt particles and the coverage increases with increasing Mn content, which resembles the concept of strong metal–support interaction (SMSI). Although the surface accessible Pt sites are reduced, new MnOx/Pt interfacial perimeter sites are created, which provide both hydrogenation and C-O activation functionalities synergistically due to the close proximity between Pt and MnOx at the interface, and therefore improve the activity. Moreover, the stability is also significantly improved due to the coverage of Pt by MnOx. This work demonstrates a simple method to tune the oxide/metal interfacial sites of inverse Pt-based catalyst for the RWGS reaction. Full article
(This article belongs to the Special Issue Catalysis on Stable Molecules (CO2, CO, CH4, N2, NH3) Activation and Their Transformation, 2nd Edition)
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<p>CO<sub>2</sub> conversion on 1PtxMn catalysts during RWGS reaction. Reaction condition: T = 400 °C, P = 1 atm, CO<sub>2</sub>/H<sub>2</sub>/Ar = 1/4/5, GHSV = 60 L·g<sup>−1</sup>·h<sup>−1</sup>, time on stream (TOS) = 20 min.</p> Full article ">Figure 2
<p>CO<sub>2</sub> conversion as a function of GHSV on Pt/SiO<sub>2</sub> and 1Pt0.5Mn. Reaction conditions: T = 400 °C, P = 1 atm, CO<sub>2</sub>/H<sub>2</sub>/Ar = 1/4/5, TOS = 20 min, GHSV = 15 L·g<sup>−1</sup>·h<sup>−1</sup>–60 L·g<sup>−1</sup>·h<sup>−1</sup>.</p> Full article ">Figure 3
<p>Stability tests of Pt/SiO<sub>2</sub> and 1Pt0.5Mn for RWGS reaction. Reaction condition: T = 400 °C, P = 1 atm, CO<sub>2</sub>/H<sub>2</sub>/Ar = 5/20/25 mL·min<sup>−1</sup>.</p> Full article ">Figure 4
<p>Arrhenius plots of CO<sub>2</sub> conversion on Pt/SiO<sub>2</sub> and 1Pt0.5Mn catalysts. T = 360–400 °C, GHSV varied in 100–600 L·g<sup>−1</sup>·h<sup>−1</sup> to control CO<sub>2</sub> conversion below 10%.</p> Full article ">Figure 5
<p>XRD patterns of 1PtxMn catalysts: (<b>A</b>) catalysts calcined at 450 °C for 4 h; (<b>B</b>) catalysts reduced at 400 °C for 1 h, as well as used catalysts after the RWGS reaction (see reaction condition in <a href="#catalysts-14-00456-f003" class="html-fig">Figure 3</a>).</p> Full article ">Figure 6
<p>(<b>A</b>) Raman spectra of 1PtxMn: (a) 1Pt0.1Mn, (b) 1Pt0.2Mn, (c) 1Pt0.5Mn, (d) 1Pt1Mn, (e) Mn/SiO<sub>2</sub>; (<b>B</b>) Raman spectra of carbon region of used 1Pt0.5Mn and Pt/SiO<sub>2</sub>, see the reaction condition in <a href="#catalysts-14-00456-f003" class="html-fig">Figure 3</a>.</p> Full article ">Figure 7
<p>H<sub>2</sub>-TPR profiles of Pt/SiO<sub>2</sub>, 1PtxMn, and Mn/SiO<sub>2</sub> catalysts.</p> Full article ">Figure 8
<p>FTIR spectra of CO adsorption on Pt/SiO<sub>2</sub>, 1Pt0.5Mn, and Mn/SiO<sub>2</sub>.</p> Full article ">Figure 9
<p>(<b>A</b>) HAADF-STEM image of Pt0.5Mn and EDS mapping of (<b>B</b>) Pt (red), (<b>C</b>) Mn (blue), and (<b>D</b>) Pt (red) + Mn (blue) of 1Pt0.5Mn. The sample was pre-reduced at 400 °C.</p> Full article ">Figure 10
<p>XPS spectra of reduced Pt/SiO<sub>2</sub> and 1Pt0.5Mn catalysts: (<b>A</b>) Pt 4f, (<b>B</b>) Mn 2p.</p> Full article ">Figure 11
<p>Schematic illustration of MnO<sub>x</sub>/Pt interface of 1PtxMn catalysts and RWGS reaction at the interface.</p> Full article ">
17 pages, 3156 KiB  
Article
Benefit of LDH-Derived Mixed Oxides for the Co-Oxidation of Toluene and CO Exhausted from Biomass Combustion
by Caroline Paris, Hadi Dib, Charf Eddine Bounoukta, Eric Genty, Christophe Poupin, Stéphane Siffert and Renaud Cousin
Catalysts 2024, 14(7), 455; https://doi.org/10.3390/catal14070455 - 16 Jul 2024
Viewed by 553
Abstract
The proposed study is devoted to highlighting the importance of mixed oxides preparation through the layered double hydroxide route for undesirable gas pollutants abatement. Different series of Cu/Al/Ce mixed oxides with similar or different stoichiometrics were prepared and compared for toluene and/or CO [...] Read more.
The proposed study is devoted to highlighting the importance of mixed oxides preparation through the layered double hydroxide route for undesirable gas pollutants abatement. Different series of Cu/Al/Ce mixed oxides with similar or different stoichiometrics were prepared and compared for toluene and/or CO oxidation. Catalyst synthesis methods influence material properties and activity for oxidation reactions. The high activity for the oxidation reactions of mixed oxides derived from LDH is explained by the Cu/Ce synergy. The presence of CO in the CO/toluene mixture does not affect the total toluene oxidation, and the toluene does not affect the total oxidation of CO conversion at low temperatures. The most effective catalytic material (Cu6Al1.2Ce0.8) presents a long lifetime stability for total toluene oxidation and resistance to CO poisoning in mixtures. Full article
(This article belongs to the Special Issue Layered Double Hydroxide-Based Catalysts for Advanced Chemical Technologies)
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<p>XRD patterns of the prepared oxide catalysts.</p> Full article ">Figure 2
<p>H<sub>2</sub>-TPR profile of the prepared oxide catalysts.</p> Full article ">Figure 3
<p>Light-off curves for toluene oxidation over oxide catalysts.</p> Full article ">Figure 4
<p>Light-off curves for CO oxidation over oxide catalysts.</p> Full article ">Figure 5
<p>Light-off curves for toluene conversion in simple and mixture feed over oxide catalysts (solid line: single toluene oxidation; dashed line: in the presence of CO).</p> Full article ">Figure 6
<p>Light-off curves for CO conversion in simple and mixture feed over oxide catalysts (solid line: single CO oxidation; dashed line: in the presence of toluene).</p> Full article ">Figure 7
<p>Light-off curves for toluene conversion in simple and mixture feed over Cu<sub>6</sub>Al<sub>2−x</sub>Ce<sub>x</sub> (x = 0–0.8) catalysts (solid line: individual toluene oxidation; dashed line: in the presence of CO).</p> Full article ">Figure 8
<p>H<sub>2</sub>-TPR profile of Cu<sub>6</sub>Al<sub>2−x</sub>Ce<sub>x</sub> catalyst series.</p> Full article ">Figure 9
<p>Light-off curves for CO conversion in simple and mixture feed over Cu<sub>6</sub>Al<sub>2−x</sub>Ce<sub>x</sub> (x = 0–0.8) catalysts (solid line: individual CO oxidation; dashed line: in the presence of toluene).</p> Full article ">Figure 10
<p>CO concentration effect on the toluene/CO mixture co-oxidation over the Cu<sub>6</sub>Al<sub>1.2</sub>Ce<sub>0.8</sub> mixed oxides catalyst. (<b>A</b>) Light-off curves for toluene conversion; (<b>B</b>) Light-off curves for CO conversion (solid line: individual toluene oxidation; dashed line: in the presence of CO).</p> Full article ">Figure 11
<p>Catalyst reuse over the Cu<sub>6</sub>Al<sub>1.2</sub>Ce<sub>0.8</sub> mixed oxides catalyst. Reaction conditions: 1000 ppm of toluene, 2000 ppm of CO, 100 mg of the catalyst and 100 mL/min of total flow.</p> Full article ">
16 pages, 4463 KiB  
Article
Electrocatalytic Hydrogen Evolution Reaction of Cobalt Triaryl Corrole Bearing Nitro Group
by Jie Zeng, Xu-You Cao, Shi-Yin Xu, Yi-Feng Qiu, Jun-Ying Chen, Li-Ping Si and Hai-Yang Liu
Catalysts 2024, 14(7), 454; https://doi.org/10.3390/catal14070454 - 15 Jul 2024
Viewed by 777
Abstract
The use of non–precious metals for electrocatalytic hydrogen reaction (HER) is particularly important for energy conservation and environmental protection. In this work, three new cobalt corroles containing o−, m−, and p−nitrobenzyl (1, 2, 3) at the [...] Read more.
The use of non–precious metals for electrocatalytic hydrogen reaction (HER) is particularly important for energy conservation and environmental protection. In this work, three new cobalt corroles containing o−, m−, and p−nitrobenzyl (1, 2, 3) at the meso 10−position of the corrole macrocycle were synthesized, and their electrocatalytic hydrogen evolution reaction in organic and neutral aqueous systems was also investigated. The results show that these three cobalt corroles have significant catalytic HER activity in both systems, and the catalytic efficiency follows 1 > 3 > 2, which indicates that the position of the nitro group can affect the catalytic property of the complexes. In the organic phase, when using trifluoroacetic acid or p−toluenesulfonic acid as the proton source, the electrocatalytic HER may undergo an EECC (E: electron transfer, C: proton coupling) pathway. In a neutral aqueous system, the HER turnover frequency value of 1 is up to 137.4 h−1 at 938 mV overpotential. Full article
(This article belongs to the Section Electrocatalysis)
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<p>XPS spectra for Co 2p (<b>a</b>), N 1s (<b>b</b>) of complexes <b>1</b>–<b>3</b>.</p> Full article ">Figure 2
<p>X-ray structure of complexes <b>1</b> (<b>a</b>), <b>2</b> (<b>b</b>), <b>3</b> (<b>c</b>). Thermal ellipsoid plot (50% probability).</p> Full article ">Figure 3
<p>(<b>a</b>) CVs of the complexes <b>1</b>–<b>3</b> (0.5 mM) in DMF (0.1 M TBAP); (<b>b</b>) CVs comparison between complexes <b>1</b>–<b>3</b> and their free–base corroles.</p> Full article ">Figure 4
<p>CVs of 0.5 mM <b>1</b> (<b>a</b>), <b>2</b> (<b>b</b>), and <b>3</b> (<b>c</b>) in DMF (0.1 M TBAP); i<sub>cat</sub>/i<sub>p</sub> values at different TFA concentrations (<b>d</b>).</p> Full article ">Figure 5
<p>CVs of 0.5 mM <b>1</b> (<b>a</b>), <b>2</b> (<b>b</b>), and <b>3</b> (<b>c</b>) in DMF (0.1 M TBAP); i<sub>cat</sub>/i<sub>p</sub> values at different TsOH concentrations (<b>d</b>).</p> Full article ">Figure 6
<p>CVs of complexes <b>1</b>–<b>3</b> (2.5 µM) in aqueous neutral system.</p> Full article ">Figure 7
<p>Gas chromatogram of complexes <b>1</b>–<b>3</b> after electrolysis at −1.7 V for 1h.</p> Full article ">Figure 8
<p>Schematic of the synthesis of 2−NBPC.</p> Full article ">Figure 9
<p>Schematic of the synthesis of Complex <b>1</b>.</p> Full article ">Scheme 1
<p>Structure of three complexes <b>1</b>–<b>3</b>.</p> Full article ">Scheme 2
<p>Possible pathways for the electrocatalytic HER of complexes <b>1</b>–<b>3</b> when TFA or TsOH are used as proton sources.</p> Full article ">
17 pages, 4066 KiB  
Article
Strong Magnetic p-n Heterojunction Fe3O4-FeWO4 for Photo-Fenton Degradation of Tetracycline Hydrochloride
by Binger Bai, Guanrong Cheng, Jian Chen, Xiaoping Chen and Qizhao Wang
Catalysts 2024, 14(7), 453; https://doi.org/10.3390/catal14070453 - 14 Jul 2024
Viewed by 631
Abstract
With the abuse of antibiotics, its pollution poses an increasing threat to the environment and human health. Effective degradation of organic pollutants in water bodies is urgent. Compared to traditional treatment methods, advanced oxidation processes that have developed rapidly in recent years are [...] Read more.
With the abuse of antibiotics, its pollution poses an increasing threat to the environment and human health. Effective degradation of organic pollutants in water bodies is urgent. Compared to traditional treatment methods, advanced oxidation processes that have developed rapidly in recent years are more environmentally friendly, efficient and applicable to a wider range of organic compounds. FeWO4 was used in this study as the iron-based semiconductor material to modify and optimize the material design. Fe3O4/FeWO4 composites were prepared by a two-step hydrothermal method. The crystal structure, surface morphology, electrochemical properties and separability of the composite semiconductor were analyzed by XRD, XPS, UV-vis, SEM, EDS and Mott-Schottky. The results showed that, when the initial contaminant concentration was 30 mg/L, the initial solution pH was 4, the dosage of the catalyst was 25 mg and the dosage of hydrogen peroxide was 30 μL, the degradation efficiency of tetracycline hydrochloride (TCH) could reach 91% within 60 min, which was significantly improved compared to the performance of the single semiconductors Fe3O4 and FeWO4. In addition, the catalyst prepared in this experiment can be easily recovered by magnetic separation technology in practical application, which will not affect the turbidity of water while reducing the cost of catalyst separation and recovery. Full article
(This article belongs to the Special Issue Two-Dimensional Materials in Photo(electro)catalysis)
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Figure 1
<p>SEM images of (<b>a</b>) FeWO<sub>4</sub>, (<b>b</b>) Fe<sub>3</sub>O<sub>4</sub> and (<b>c</b>) 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO; EDS image of 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO (<b>d</b>), mapping spectrum of (<b>e</b>) O, (<b>f</b>) Fe and (<b>g</b>) W; (<b>h</b>) EDAX of 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO.</p> Full article ">Figure 2
<p>(<b>a</b>) XRD pattern image, (<b>b</b>) FT-IR diagram, (<b>c</b>) Nitrogen adsorption–desorption curves and (<b>d</b>) pore size distribution curves of FeWO<sub>4</sub>, Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>3</sub>O<sub>4</sub>/FWO.</p> Full article ">Figure 3
<p>XPS spectra of the 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO composite: (<b>a</b>) survey, (<b>b</b>) Fe 2p, (<b>c</b>) W 4f and (<b>d</b>) O 1s.</p> Full article ">Figure 4
<p>(<b>a</b>) It curves and (<b>b</b>) EIS curves of catalysts; (<b>c</b>) The UV-vis absorption spectra of FeWO<sub>4</sub>, Fe<sub>3</sub>O<sub>4</sub> and 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO; (<b>d</b>) The band gap of semiconductor; Mott-Schottky chart of (<b>e</b>) FeWO<sub>4</sub> and (<b>f</b>) Fe<sub>3</sub>O<sub>4</sub>.</p> Full article ">Figure 5
<p>(<b>a</b>) Different ratios of Fe<sub>3</sub>O<sub>4</sub>/FWO and (<b>b</b>) degradation kinetics, (<b>c</b>) TCH degradation efficiency of different systems and (<b>d</b>) degradation kinetics.</p> Full article ">Figure 6
<p>Effects of (<b>a</b>) pH, (<b>b</b>) the amount of H<sub>2</sub>O<sub>2</sub>, (<b>c</b>) catalyst dosage and (<b>d</b>) initial TCH concentration on degradation performance.</p> Full article ">Figure 7
<p>Recycle performance of 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO.</p> Full article ">Figure 8
<p>Magnetic test comparison of (<b>a</b>) FeWO<sub>4</sub>, (<b>b</b>) 50%-Fe3O4/FWO, (<b>c</b>) 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO after react and (<b>d</b>) 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO after three reactions.</p> Full article ">Figure 9
<p>Possible degradation products and pathways of TCH.</p> Full article ">Figure 10
<p>Possible mechanism of degradation of TCH in the 50%-Fe<sub>3</sub>O<sub>4</sub>/FWO photo-Fenton system.</p> Full article ">
27 pages, 4004 KiB  
Review
Catalytic Applications in the Production of Hydrotreated Vegetable Oil (HVO) as a Renewable Fuel: A Review
by Nur-Sultan Mussa, Kainaubek Toshtay and Mickael Capron
Catalysts 2024, 14(7), 452; https://doi.org/10.3390/catal14070452 - 14 Jul 2024
Viewed by 849
Abstract
The significance and challenges of hydrotreatment processes for vegetable oils have recently become apparent, encompassing various reactions like decarbonylation, decarboxylation, and hydrogenation. Heterogeneous noble or transition metal catalysts play a crucial role in these reactions, offering high selectivity in removing oxygen and yielding [...] Read more.
The significance and challenges of hydrotreatment processes for vegetable oils have recently become apparent, encompassing various reactions like decarbonylation, decarboxylation, and hydrogenation. Heterogeneous noble or transition metal catalysts play a crucial role in these reactions, offering high selectivity in removing oxygen and yielding desired hydrocarbons. Notably, both sulphided and non-sulphided catalysts exhibit effectiveness, with the latter gaining attention due to health and toxicity concerns associated with sulphiding agents. Nickel-based catalysts, such as NiP and NiC, demonstrate specific properties and tendencies in deoxygenation reactions, while palladium supported on activated carbon catalysts shows superior activity in hydrodeoxygenation. Comparisons between the performances of different catalysts in various hydrotreatment processes underscore the need for tailored approaches. Transition metal phosphides (TMP) emerge as promising catalysts due to their cost-effectiveness and environmental friendliness. Ultimately, there is an ongoing pursuit of efficient catalysts and the importance of further advancements in catalysis for the future of vegetable oil hydrotreatment. Full article
(This article belongs to the Section Biomass Catalysis)
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<p>Triglyceride conversion pathways in the presence of hydrogen. Reproduced with permission, Ref. [<a href="#B27-catalysts-14-00452" class="html-bibr">27</a>].</p> Full article ">Figure 2
<p>Representative pressure and temperature profile during hydrotreating of soybean oil using 57.6 wt% Ni/SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub>. Reproduced with permission, Ref. [<a href="#B27-catalysts-14-00452" class="html-bibr">27</a>].</p> Full article ">Figure 3
<p>The XRD patterns of (a) NiC, (b) NiS, (c) NiP, and (d) γ-Al<sub>2</sub>O<sub>3</sub>. Reproduced with permission, Ref. [<a href="#B45-catalysts-14-00452" class="html-bibr">45</a>].</p> Full article ">Figure 4
<p>The XRD patterns of Pd/C and NiMo/γ-Al<sub>2</sub>O<sub>3</sub>. Reproduced with permission, Ref. [<a href="#B92-catalysts-14-00452" class="html-bibr">92</a>].</p> Full article ">Figure 5
<p>The proposed scheme for the reaction pathway of diesel-like hydrocarbon production from vegetable oil utilising Pt/Ni-Al<sub>2</sub>O<sub>3</sub> + Pd/C combined catalysts. Reproduced with permission, Ref. [<a href="#B100-catalysts-14-00452" class="html-bibr">100</a>].</p> Full article ">Figure 6
<p>Catalyst activity and conversion vs. time under conditions of repeated standard experiment. Reproduced with permission, Ref. [<a href="#B101-catalysts-14-00452" class="html-bibr">101</a>].</p> Full article ">Figure 7
<p>Triangular prism and tetrakaidecahedral structures of phosphides. Reproduced with permission, Ref. [<a href="#B112-catalysts-14-00452" class="html-bibr">112</a>].</p> Full article ">Figure 8
<p>Crystal configurations of metal-rich phosphides. Reproduced with permission, Ref. [<a href="#B112-catalysts-14-00452" class="html-bibr">112</a>].</p> Full article ">Figure 9
<p>Possible hydrodeoxygenation (HDO) mechanism supported on transition metal phosphides. Reproduced under terms of the CC-BY license [<a href="#B124-catalysts-14-00452" class="html-bibr">124</a>].</p> Full article ">Figure 10
<p>Deoxygenation of methyl laurate with different catalysts. (<b>A</b>). The conversion of methyllaurate using different catalysts. (<b>B</b>). The total selectivity for C11 and C12 hydrocarbons of different catalysts. (<b>C</b>). The influence of the C11/C12 molar ratios on catalysts. (<b>D</b>). The total selectivity (Soxy) of the oxygenated intermediates. Reproduced with permission, Ref. [<a href="#B129-catalysts-14-00452" class="html-bibr">129</a>].</p> Full article ">
20 pages, 2772 KiB  
Review
Enhancing Trace Pb2⁺ Detection via Novel Functional Materials for Improved Electrocatalytic Redox Processes on Electrochemical Sensors: A Short Review
by Duowen Yang, Xinyu Wang and Hao Xu
Catalysts 2024, 14(7), 451; https://doi.org/10.3390/catal14070451 - 14 Jul 2024
Viewed by 909
Abstract
The efficient detection of lead ions (Pb2⁺) is significant for environmental protection and public health. Electrochemical detection has emerged as one of the most promising technologies due to its low detection limits, high sensitivity, and cost-effectiveness. However, significant challenges remain, including [...] Read more.
The efficient detection of lead ions (Pb2⁺) is significant for environmental protection and public health. Electrochemical detection has emerged as one of the most promising technologies due to its low detection limits, high sensitivity, and cost-effectiveness. However, significant challenges remain, including issues related to sensitivity, selectivity, interference, and the stability of electrode materials. This review explores recent advancements in the field, focusing on integrating novel catalytic materials and innovative sensor construction methods. Particular emphasis is placed on enhancing the electrocatalytic redox processes on sensor surfaces using advanced nanomaterials such as MXenes, ferrite-based nanomaterials, carbon nanomaterials, and metal–organic frameworks (MOFs). Additionally, the role of biomaterials and enzymes in improving electrochemical sensors’ selectivity and anti-interference capabilities is discussed. Despite the impressive low detection limits achieved, real-world applications present additional challenges due to the complex composition of environmental samples. The review concludes with future perspectives on overcoming these challenges by leveraging the unique properties of catalytic materials to develop more effective and reliable electrochemical sensors for trace Pb2⁺ detection. Full article
(This article belongs to the Special Issue Electrocatalytic Wastewater Treatment: Resource Utilization and New Technology)
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<p>Type of equipment for detecting trace amounts of Pb<sup>2+</sup> ions and the relevant information.</p> Full article ">Figure 2
<p>Comparison of the key capabilities of carbon-based nanomaterials, metal nanomaterials, and inorganic composite materials for electrochemical detection of Pb<sup>2+</sup> ions. The radar chart illustrates the electron conductivity, catalytic activity, preconcentration capacity, selectivity, and stability of each material type, highlighting their respective strengths in enhancing sensor performance (<b>a</b>). Schematic illustration of the benefits of hybrid engineering and defect engineering in improving the performance of electrochemical sensors. Hybrid engineering combines different materials to optimize electron transport capacity and enhance overall sensor properties. Defect engineering introduces additional active sites and adsorption sites, which increase the efficiency of oxidation or reduction reactions and enhance the interaction between the electrocatalytic material and reactants (<b>b</b>).</p> Full article ">Figure 3
<p>The in situ synthesis of BiNPs@Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> and its application in modifying GCE (<b>a</b>). The preparation of BiNPs @ CoFe<sub>2</sub>O<sub>4</sub> nanocomposite and its application in modifying GCE (<b>b</b>). The combination of ZIF-67, MWCNTs, and Nafion membrane endowed the electrode with high sensitivity and improved anti-interference capabilities against Fe<sup>3+</sup>, Co<sup>2+</sup>, and Mn<sup>2+</sup> ions (<b>c</b>).</p> Full article ">Figure 4
<p>HD-CNT<span class="html-italic">f</span> was directly embedded into polymer matrix to prepare electrodes (<b>a</b>). The combination of L-cys and GR-CS endowed the electrode with higher sensitivity (<b>b</b>). The introduction of AuNPs in the PrGO/AuNPs/Sal-Cys/GCE composite increased the actual surface area and improved electron transfer, leading to the highly sensitive detection of Pb<sup>2+</sup> ions (<b>c</b>). The preparation of BiNPs modified aerogel and its direct use as the working electrode (<b>d</b>).</p> Full article ">Figure 5
<p>“Ion-imprinting chitosan” was used to improve the selectivity of the electrode (<b>a</b>). The effects of different binding modes of β-cyclodextrin and CNTs on electrochemical sensors (<b>b</b>).</p> Full article ">Figure 6
<p>Amplification detection of Pb<sup>2+</sup> based on DNA and deoxyribonuclease (<b>a</b>). The amplification strategy for Pb<sup>2+</sup> sensing based on a micropipette tip-based miniaturized electrochemical device [<a href="#B74-catalysts-14-00451" class="html-bibr">74</a>] (<b>b</b>).</p> Full article ">
48 pages, 11437 KiB  
Review
Advancing Plastic Recycling: A Review on the Synthesis and Applications of Hierarchical Zeolites in Waste Plastic Hydrocracking
by Muhammad Usman Azam, Waheed Afzal and Inês Graça
Catalysts 2024, 14(7), 450; https://doi.org/10.3390/catal14070450 - 12 Jul 2024
Viewed by 929
Abstract
The extensive use of plastics has led to a significant environmental threat due to the generation of waste plastic, which has shown significant challenges during recycling. The catalytic hydrocracking route, however, is viewed as a key strategy to manage this fossil-fuel-derived waste into [...] Read more.
The extensive use of plastics has led to a significant environmental threat due to the generation of waste plastic, which has shown significant challenges during recycling. The catalytic hydrocracking route, however, is viewed as a key strategy to manage this fossil-fuel-derived waste into plastic-derived fuels with lower carbon emissions. Despite numerous efforts to identify an effective bi-functional catalyst, especially metal-loaded zeolites, the high-performing zeolite for hydrocracking plastics has yet to be synthesized. This is due to the microporous nature of zeolite, which results in the diffusional limitations of bulkier polymer molecules entering the structure and reducing the overall cracking of plastic and catalyst cycle time. These constraints can be overcome by developing hierarchical zeolites that feature shorter diffusion paths and larger pore sizes, facilitating the movement of bulky polymer molecules. However, if the hierarchical modification process of zeolites is not controlled, it can lead to the synthesis of hierarchical zeolites with compromised functionality or structural integrity, resulting in reduced conversion for the hydrocracking of plastics. Therefore, we provide an overview of various methods for synthesizing hierarchical zeolites, emphasizing significant advancements over the past two decades in developing innovative strategies to introduce additional pore systems. However, the objective of this review is to study the various synthesis approaches based on their effectiveness while developing a clear link between the optimized preparation methods and the structure-activity relationship of the resulting hierarchical zeolites used for the hydrocracking of plastics. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Sustainable Conversion of Biomass, Carbon Dioxide and Plastic Waste into Fuels and Chemicals)
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<p>Free radical mechanism of non-catalytic hydrocracking of plastics.</p> Full article ">Figure 2
<p>SEM images of the (<b>a</b>) parent HZSM-5 and post-treated HZSM-5 zeolites using 0.1 M NaOH at 65 °C for (<b>b</b>) 2 h, (<b>c</b>) 5 h, and (<b>d</b>) 0.2 M NaOH at 80 °C for 5 h, Nitrogen isotherms for (<b>e</b>) as-received and (<b>e</b>–<b>h</b>) alkali-treated ZSM-5 in a 0.2 M NaOH solution at 353 K for different treatment time. Adopted with permission from Ref. [<a href="#B47-catalysts-14-00450" class="html-bibr">47</a>], Copyright 2001 Elsevier.</p> Full article ">Figure 3
<p>(<b>a</b>) Product yield distribution by carbon number over pristine HY(30) and various desilicated zeolite samples, Reprinted from Ref. [<a href="#B24-catalysts-14-00450" class="html-bibr">24</a>] under a Creative Commons Attribution Non-Commercial License 4.0 (CC BY-NC), Impact of degree of desilication on the catalytic activity of MOR for the hydrocracking of HDPE. Comparison of (<b>b</b>) conversion and (<b>c</b>) average carbon number °C. Reprinted with permission from Ref. [<a href="#B46-catalysts-14-00450" class="html-bibr">46</a>], Copyright 2023 American Chemical Society.</p> Full article ">Figure 4
<p>(<b>a</b>) Correlation plot between the hydrocracking of HDPE and Interplay Factor (IF), where solid red bar showed the conversion and dotted lines represented the interplay factor (<b>b</b>) Evolution of different factors influencing the activity catalyst. Reprinted with permission from Ref. [<a href="#B50-catalysts-14-00450" class="html-bibr">50</a>], Copyright 2023 Elsevier.</p> Full article ">Figure 5
<p>Pictorial representation of the impact of Si/Al ratio on the desilication process of MFI zeolite in alkaline media. Reprinted with permission from Ref. [<a href="#B48-catalysts-14-00450" class="html-bibr">48</a>], Copyright 2004 American Chemical Society.</p> Full article ">Figure 6
<p>(<b>a</b>) Product selectivity and conversion of surgical face masks through hydrocracking over zeolite Y with different loading of Ni and steamed zeolite Y with 5 wt.% Ni in a 100 mL autoclave reactor, 10 bar initial cold H<sub>2</sub> pressure, feed to catalyst ratio of 10:1 (by weight), 325 °C for 120 min residence time. (<b>b</b>) Product selectivity is based on the carbon number of the <span class="html-italic">n</span>-heptane soluble liquids. Adopted with permission from Ref. [<a href="#B67-catalysts-14-00450" class="html-bibr">67</a>], Copyright 2023 Elsevier.</p> Full article ">Figure 7
<p>Mechanism of mordenite recrystallization to micro/mesoporous structure. Reprinted with permission from Ref. [<a href="#B85-catalysts-14-00450" class="html-bibr">85</a>], Copyright 2013 Elsevier.</p> Full article ">Figure 8
<p>(<b>a</b>) Schematic illustration and characteristic adsorption-desorption curves of a zeolite (green), a desilicated (blue), and a surfactant-templated zeolite (red) plotted against the time or the intensity of the applied treatment, (<b>b</b>) Isotherms for Ar adsorption and desorption with the corresponding schematic explanation for each type of zeolite: the original zeolite, ST-150 treated for 3 h, and ST-150 treated for 48 h. The diagrams at the bottom depict the nature of porosity for each case. Reprinted with permission from Ref. [<a href="#B86-catalysts-14-00450" class="html-bibr">86</a>], Copyright 2017 American Chemical Society.</p> Full article ">Figure 9
<p>(<b>a</b>,<b>b</b>) SEM images of commercial Y and Y-H zeolites after recrystallization and (<b>c</b>) effects of catalyst on the conversion and selectivity for hydrocracking PE at 280 °C under 3 MPa H<sub>2</sub>. Reprinted with permission from Ref. [<a href="#B91-catalysts-14-00450" class="html-bibr">91</a>], Copyright 2023 American Chemical Society.</p> Full article ">Figure 10
<p>(<b>a</b>) X-ray diffractograms of parent and hierarchical FAU catalysts. (<b>b</b>) N<sub>2</sub> physisorption isotherms of parent and hierarchical FAU materials, (<b>c</b>) Solid conversion and solid conversion rate, and (<b>d</b>) gaseous product selectivity and yield for PE catalytic cracking on parent and hierarchical FAU catalysts. Orange and purple solid bars indicate C<sub>2</sub>–C<sub>3</sub> and C<sub>4</sub>–C<sub>7</sub> linear alkanes, respectively, while orange and purple striped bass indicate C<sub>1</sub> and C<sub>4</sub>–C<sub>7</sub> isoalkanes, respectively. * Indicates that C<sub>4</sub>–C<sub>7</sub> alkenes are also present and included under this value. Reprinted with permission from Ref. [<a href="#B92-catalysts-14-00450" class="html-bibr">92</a>], Copyright 2024 American Chemical Society.</p> Full article ">Figure 11
<p>(<b>a</b>) Carbon-based hard template materials for the synthesis of hierarchical zeolites Adopted with permission from Ref. [<a href="#B112-catalysts-14-00450" class="html-bibr">112</a>], Copyright 2006 Elsevier (<b>b</b>) confined space synthesis of zeolite. Reprinted with permission from Ref. [<a href="#B102-catalysts-14-00450" class="html-bibr">102</a>] Copyright 2006 Elsevier, (<b>c</b>) Hydrophilic carbon templated synthesis of mesoporous ZSM-5. Reprinted with permission from Ref. [<a href="#B109-catalysts-14-00450" class="html-bibr">109</a>] Copyright 2016 Elsevier.</p> Full article ">Figure 12
<p>(<b>a</b>) Product yield and product distribution for the cracking of HDPE over the prepared catalysts. Adopted from Ref. [<a href="#B116-catalysts-14-00450" class="html-bibr">116</a>]. (<b>b</b>) Schematic of the formation of 3DOm-i zeolite confined in the pore space of 3DOm carbon. Reprinted with permission from Ref. [<a href="#B117-catalysts-14-00450" class="html-bibr">117</a>] Copyright 2011 American Chemical Society.</p> Full article ">Figure 13
<p>(<b>a</b>) Conceptional approach to the synthesis of a zeolite with intracrystalline mesopores using a silylated polymer as the mesoporogen, Adopted from Ref. [<a href="#B132-catalysts-14-00450" class="html-bibr">132</a>], (<b>b</b>) TG curves of LDPE thermal cracking (blank) and catalytic over TZ and MZ-3. Reprint from Ref. [<a href="#B139-catalysts-14-00450" class="html-bibr">139</a>] under the terms of the CC 4.0, Copyright 2018 Springer.</p> Full article ">Figure 14
<p>Schematic diagram showing the distribution of PHAPTMS on the surface of protozeolitic units after the silanization step (<b>A</b>), the incorporation of alkoxy moieties by alkoxylation when the silanization proceeds in the presence of alcohols (<b>B</b>), and the interaction between PHAPTMS and <span class="html-italic">n</span>-butoxy grafted species in close vicinity on the surface of protozeolitic units (<b>C</b>). Reprinted with permission from Ref. [<a href="#B141-catalysts-14-00450" class="html-bibr">141</a>], Copyright 2011 Elsevier.</p> Full article ">Figure 15
<p>Selectivity in PS hydrocracking: (<span class="html-fig-inline" id="catalysts-14-00450-i001"><img alt="Catalysts 14 00450 i001" src="/catalysts/catalysts-14-00450/article_deploy/html/images/catalysts-14-00450-i001.png"/></span>) 573 K, (<span class="html-fig-inline" id="catalysts-14-00450-i002"><img alt="Catalysts 14 00450 i002" src="/catalysts/catalysts-14-00450/article_deploy/html/images/catalysts-14-00450-i002.png"/></span>) 598 K, (<span class="html-fig-inline" id="catalysts-14-00450-i003"><img alt="Catalysts 14 00450 i003" src="/catalysts/catalysts-14-00450/article_deploy/html/images/catalysts-14-00450-i003.png"/></span>) 623 K, (<span class="html-fig-inline" id="catalysts-14-00450-i004"><img alt="Catalysts 14 00450 i004" src="/catalysts/catalysts-14-00450/article_deploy/html/images/catalysts-14-00450-i004.png"/></span>) 648 K. Reprinted with permission from Ref. [<a href="#B44-catalysts-14-00450" class="html-bibr">44</a>], Copyright 2014 Elsevier.</p> Full article ">Figure 16
<p>(<b>a</b>) Conversion in a LDPE-cracking reaction for layer-like zeolite Y samples (LY-0.144-H and LY-0.225-H) and commercial zeolite Y samples (CBV100-H and CBV760-H) as catalysts and the conversion in the absence of any catalyst (LDPE). (<b>b</b>) Distribution of the cracking products: selectivity (%) (upper); the share (%) of the paraffin and olefin fractions (middle); and the ratio between the branched and linear compounds in the C<sub>4</sub> fraction (lower). Reprinted with permission from Ref. [<a href="#B143-catalysts-14-00450" class="html-bibr">143</a>] under licensed CC-BY 4.0, Copyright 2022 American Chemical Society.</p> Full article ">Figure 17
<p>Formation of (<b>c</b>) hierarchical BEA zeolite from (<b>a</b>) a dense precursor gel; (<b>b</b>) contraction (densification) and partial conversion of the gel into nanozeolites after short SAC treatment; at this stage, filtration yields a colloidal solution of zeolite beta. Reprinted with permission from Ref. [<a href="#B149-catalysts-14-00450" class="html-bibr">149</a>], Copyright 2011 American Chemical Society.</p> Full article ">Figure 18
<p>(<b>a</b>) N<sub>2</sub> adsorption-desorption isotherms of hierarchical materials with or without Ni, as well as their parents, are used for zeolitization approaches. Insets in the graph display the pore size distribution obtained from desorption branches (BJH model), The average values for the cell (D<sub>cell</sub>) and window (D<sub>win</sub>) diameters, estimated by the BJH method applied to the adsorption and desorption branches, were D<sub>cell</sub> = 20 and D<sub>win</sub> = 9 nm, respectively. (<b>b</b>) HDPE hydrocracking over Al-MCF (Z1 and Z2) and HZSM5 (Conditions: 260 °C for 60 min under 20 bar of H<sub>2</sub>, using 20 wt.% of catalyst). Reprinted with permission from Ref. [<a href="#B50-catalysts-14-00450" class="html-bibr">50</a>], Copyright 2023 Elsevier, (<b>c</b>) Selectivity by carbon atom number of the feed and the hydro-reforming products. Reprinted with permission from Ref. [<a href="#B151-catalysts-14-00450" class="html-bibr">151</a>], Copyright 2014 Elsevier.</p> Full article ">
23 pages, 8965 KiB  
Article
Novel Starch-Modified NiCrMn-LDH-Based Composite for Photocatalytic Degradation of Reactive Orange 13
by Muhammad Usman, Muhammad Babar Taj, Afaf Almasoudi, Doaa F. Baamer, Omar Makram Ali, Muhammad Imran Khan, Ismat Bibi, Mobeen Ur Rehman, Rabia Rasheed, Ahmad Raheel, Mushtaq Hussain Lashari, Abdallah Shanableh and Javier Fernandez-Garcia
Catalysts 2024, 14(7), 449; https://doi.org/10.3390/catal14070449 - 12 Jul 2024
Viewed by 634
Abstract
Water pollution has become a great challenge today. To address this problem regarding wastewater treatment by removing toxic synthetic dyes from wastewater, this research focused on the synthesis of a novel starch-modified NiCrMn-layered double hydroxide composite through the coprecipitation method and applied it [...] Read more.
Water pollution has become a great challenge today. To address this problem regarding wastewater treatment by removing toxic synthetic dyes from wastewater, this research focused on the synthesis of a novel starch-modified NiCrMn-layered double hydroxide composite through the coprecipitation method and applied it as a photocatalyst for the degradation of reactive orange 13 dye. The synthesized photocatalyst was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), point of zero charges (PZC), dynamic light scattering (DLS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Zeta potential techniques. These techniques revealed different characteristics of photocatalysts, like surface and structural properties. According to BET analysis, the final composite had 2.5 × 102 m2/g BET-specific surface area with a 45.56 nm pore radius value, and the overall composite found as mesoporous. Similarly, in DLS analysis, bare NiCrMn-LDH had 404 nm hydrodynamic size, which increased for the final starch composite up to 667 nm. Zeta potential value changed from −14.56 mV to 0.95 mV after the incorporation of starch with NiCrMn-LDH. They confirmed the incorporation of starch with trimetallic NiCrMn-layered double hydroxide (2:1:2). Starch association improved the properties of the photocatalyst like surface area. Different parameters like pH value, initial dye concentration, photocatalyst dose, hydrogen peroxide concentration, effect of sacrificial reagent, and effect of inorganic anions were studied for degradation of RO13. Overall, the photocatalysis process for RO13 followed pseudo-first-order kinetics. Photocatalytic degradation reactions for reactive orange 13 were conducted with an initial dye concentration of 10 mg/L, photocatalyst dosage of 20 mg/50 mL, and pH value at 3 in the presence of sunlight, resulting in an impressive degradation removal rate of 86.68%. This remarkable degradation ability of the photocatalyst for reactive orange 13 proves this composite was highly efficient. Full article
(This article belongs to the Section Photocatalysis)
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<p>X-ray diffraction spectra of starch, NiCrMn-LDH and its composite.</p> Full article ">Figure 2
<p>SEM images of NiCrMn-LDH (<b>a</b>–<b>c</b>) and starch/NiCrMn-LDH composite (<b>d</b>–<b>f</b>), EDX images of NiCrMn-LDH (<b>g</b>), and starch/NiCrMn-LDH composite (<b>h</b>).</p> Full article ">Figure 2 Cont.
<p>SEM images of NiCrMn-LDH (<b>a</b>–<b>c</b>) and starch/NiCrMn-LDH composite (<b>d</b>–<b>f</b>), EDX images of NiCrMn-LDH (<b>g</b>), and starch/NiCrMn-LDH composite (<b>h</b>).</p> Full article ">Figure 2 Cont.
<p>SEM images of NiCrMn-LDH (<b>a</b>–<b>c</b>) and starch/NiCrMn-LDH composite (<b>d</b>–<b>f</b>), EDX images of NiCrMn-LDH (<b>g</b>), and starch/NiCrMn-LDH composite (<b>h</b>).</p> Full article ">Figure 3
<p>FTIR spectrum of starch/NiCrMn-LDH composite (<b>a</b>), NiCrMn-LDH (<b>b</b>), and starch (<b>c</b>).</p> Full article ">Figure 4
<p>DLS analysis (<b>a</b>) and ZETA potential study (<b>b</b>) of starch/NiCrMn-LDH composite, NiCrMn-LDH, and starch.</p> Full article ">Figure 5
<p>Determination of PZC value for starch/NiCrMn-LDH composite, NiCrMn-LDH, and starch (black line represent the pH initial).</p> Full article ">Figure 6
<p>N2 adsorption-desorption isotherm (<b>a</b>) BJH analysis for pore radius (<b>b</b>) for starch/NiCrMn-LDH composite.</p> Full article ">Figure 7
<p>TGA analysis (<b>a</b>) and DSC analysis (<b>b</b>) of starch/NiCrMn-LDH, NiCrMn-LDH, and starch.</p> Full article ">Figure 8
<p>The gradual decrease in absorbance peak of RO13 during photocatalytic degradation.</p> Full article ">Figure 9
<p>Effect of photocatalyst dose in photocatalytic degradation of RO13.</p> Full article ">Figure 10
<p>Effect of initial dye concentration in photocatalytic degradation of RO13.</p> Full article ">Figure 11
<p>Effect of pH in photocatalytic degradation of RO13.</p> Full article ">Figure 12
<p>Effect of inorganic salts in photocatalytic degradation of RO13.</p> Full article ">Figure 13
<p>Effect of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) concentration in photocatalytic degradation of RO13.</p> Full article ">Figure 14
<p>Effect of sacrificial reagent in photocatalytic degradation of RO13.</p> Full article ">Figure 15
<p>Pseudo-first-order kinetics model for photocatalytic degradation of RO13.</p> Full article ">Figure 16
<p>Mechanism of photocatalytic degradation of RO13.</p> Full article ">Figure 17
<p>Schematic diagram for preparation of starch/NiCrMn-ldh composite.</p> Full article ">
19 pages, 2393 KiB  
Article
The Influence of Au Loading and TiO2 Support on the Catalytic Wet Air Oxidation of Glyphosate over TiO2+Au Catalysts
by Gregor Žerjav, Alen Albreht and Albin Pintar
Catalysts 2024, 14(7), 448; https://doi.org/10.3390/catal14070448 - 12 Jul 2024
Cited by 1 | Viewed by 539
Abstract
This study aimed to explore the impact of varying amounts of added Au (0.5 to 2 wt.%) and the structural characteristics of anatase TiO2 supports (nanoparticles (TP, SBET = 88 m2/g) and nanorods (TR, SBET = 105 m [...] Read more.
This study aimed to explore the impact of varying amounts of added Au (0.5 to 2 wt.%) and the structural characteristics of anatase TiO2 supports (nanoparticles (TP, SBET = 88 m2/g) and nanorods (TR, SBET = 105 m2/g)) on the catalytic efficiency of TiO2+Au catalysts in eliminating the herbicide glyphosate from aqueous solutions via the catalytic wet air oxidation (CWAO) process. The investigation was conducted using a continuous-flow trickle-bed reactor. Regardless of the TiO2 support and the amount of Au added, the addition of Au has a positive effect on the glyphosate degradation rate. Regarding the amount of Au added, the highest catalytic activity was observed with the TP + 1% Au catalyst, which had a higher Schottky barrier (SB) than the TP + 2% Au catalyst, which helped the charge carriers in the TiO2 conduction band to increase their reduction potential by preventing them from returning to the Au. The role of glyphosate degradation product adsorption on the catalyst surface is crucial for sustaining the long-term catalytic activity of the investigated TiO2+Au materials. This was particularly evident in the case of the TR + 1% Au catalyst, which had the highest glyphosate degradation rate at the beginning of the CWAO experiment, but its catalytic activity then decreased over time due to the adsorption of glyphosate degradation products, which was favoured by the presence of strong acidic sites. In addition, the TR + 1% Au solid had the smallest average Au particle size of all analyzed materials, which were more easily deactivated by the adsorption of glyphosate degradation products. The analysis of the degradation products of glyphosate shows that the oxidation of glyphosate in the liquid phase involves the rupture of C–P and C–N bonds, as amino-methyl-phosphonic acid (AMPA), glyoxylic acid and sarcosine were detected. Full article
(This article belongs to the Special Issue Environmental Catalysis in Advanced Oxidation Processes, 2nd Edition)
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<p>XRD patterns of both pure TiO<sub>2</sub> supports and TiO<sub>2</sub>+Au catalysts with varying Au loadings are presented. In these patterns, solid vertical lines indicate anatase TiO<sub>2</sub> (JCPDS 00-021-1272), while dotted vertical lines denote fcc Au (JCPDS 01-1174).</p> Full article ">Figure 2
<p>SEM images of the TiO<sub>2</sub>+Au catalysts investigated.</p> Full article ">Figure 3
<p>Determination of VBM of bare TiO<sub>2</sub> supports and TiO<sub>2</sub>+Au catalysts by XPS analysis.</p> Full article ">Figure 4
<p>TPD of pyridine from the surface of the catalysts studied.</p> Full article ">Figure 5
<p>(<b>a</b>) Glyphosate and (<b>b</b>) TOC conversion as a function of time on the stream obtained in the trickle-bed reactor in the presence of prepared materials.</p> Full article ">Figure 6
<p>(<b>a</b>) TGA–TPO profiles of the TiO<sub>2</sub> and TiO<sub>2</sub>+Au samples after use in the CWAO process. (<b>b</b>) Derivation of mass as a function of temperature.</p> Full article ">
36 pages, 3154 KiB  
Review
Photocatalytic Application of Polymers in Removing Pharmaceuticals from Water: A Comprehensive Review
by Sanja J. Armaković, Stevan Armaković and Maria M. Savanović
Catalysts 2024, 14(7), 447; https://doi.org/10.3390/catal14070447 - 12 Jul 2024
Viewed by 871
Abstract
This comprehensive review covers recent advancements in utilizing various types of polymers and their modifications as photocatalysts for the removal of pharmaceutical contaminants from water. It also considers polymers that enhance the photocatalytic properties of other materials, highlighting their dual role in improving [...] Read more.
This comprehensive review covers recent advancements in utilizing various types of polymers and their modifications as photocatalysts for the removal of pharmaceutical contaminants from water. It also considers polymers that enhance the photocatalytic properties of other materials, highlighting their dual role in improving water purification efficiency. Over the past decades, significant progress has been made in understanding the photocatalytic properties of polymers, including organic, inorganic, and composite materials, and their efficacy in degrading pharmaceuticals. Some of the most commonly used polymers, such as polyaniline, poly(p-phenylene vinylene), polyethylene oxide, and polypyrole, and their properties have been reviewed in detail. Physical modification techniques (mechanical blending and extrusion processing) and chemical modification techniques (nanocomposite formation, plasma modification techniques, surface functionalization, and cross-linking) have been discussed as appropriate for modifying polymers in order to increase their photocatalytic activity. This review examines the latest research findings, including the development of novel polymer-based photocatalysts and their application in the removal of pharmaceutical compounds, as well as optimization strategies for enhancing their performance. Additionally, challenges and future directions in this field are discussed to guide further research efforts. Full article
(This article belongs to the Special Issue Advanced Catalytic Materials and Processes for Water/Wastewater Treatment)
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<p>Overview of various photocatalytic applications of polymers. Reprinted with permission from Ref. [<a href="#B19-catalysts-14-00447" class="html-bibr">19</a>], copyright Royal Society of Chemistry.</p> Full article ">Figure 2
<p>Optimization of injection stretch blow-molding. (<b>a</b>–<b>f</b>) illustrate the process steps. Straight arrows follow the process sequence; curved arrows follow the optimization sequence. N—screw speed, <span class="html-italic">T</span><sub>b</sub>—barrel temperature profile, <span class="html-italic">V</span><sub>inj</sub>—injection volume. Reprinted with permission from Ref. [<a href="#B159-catalysts-14-00447" class="html-bibr">159</a>], copyright MDPI.</p> Full article ">Figure 3
<p>The scheme of photocatalysis, based on a (<b>a</b>) conducting polymer (CP) nanocomposite and (<b>b</b>) conducting polymer–metal oxide hybrid modification. Reprinted and adjusted with permission from Ref. [<a href="#B192-catalysts-14-00447" class="html-bibr">192</a>], copyright MDPI.</p> Full article ">Figure 4
<p>Venn diagram illustrating the connections between distinct computational methods for molecular simulations.</p> Full article ">Figure 5
<p>Suggested workflow for geometrical optimization and property calculations of long polymer chains.</p> Full article ">Figure 6
<p>PMMA optimized via (<b>a</b>) GFN2-xTB and (<b>b</b>) B3LYP-D3/6-31G(d,p). Gray spheres represent carbon atoms, white spheres represent hydrogen atoms, red spheres represent oxygen atoms.</p> Full article ">Figure 7
<p>(<b>a</b>) RDG scatter plot and (<b>b</b>) RDG surfaces of PMMA polymer chain.</p> Full article ">Figure 8
<p>Advantages of polymers in photocatalytic removal of pharmaceutical contaminants from water.</p> Full article ">
19 pages, 2772 KiB  
Article
Staphylococcus aureus Alkaline Protease: A Promising Additive for Industrial Detergents
by Mona Alonazi
Catalysts 2024, 14(7), 446; https://doi.org/10.3390/catal14070446 - 12 Jul 2024
Viewed by 620
Abstract
A novel alkaline serine protease, derived from the Staphylococcus aureus strain ALA1 previously isolated from dromedary milk, was subjected to purification and characterization. Optimal protease production occurred under specific culture conditions. The purified protease, designated S. aureus Pr with a molecular mass of [...] Read more.
A novel alkaline serine protease, derived from the Staphylococcus aureus strain ALA1 previously isolated from dromedary milk, was subjected to purification and characterization. Optimal protease production occurred under specific culture conditions. The purified protease, designated S. aureus Pr with a molecular mass of 23,662 Da and an N-terminal sequence, showed an approximately 89% similar identity with those of other Staphylococcus strains. It exhibited its highest enzymatic activity at a pH of 10.0 and 60 °C in the presence of 3 mM Ca2+. Remarkable thermostability was observed at temperatures up to 70 °C and within a pH range of 6.0 to 10.0 for 2 h. The presence of Ca2+ or Mg2+ and Zn2+ significantly enhanced both enzymatic activity and thermal stability. Additionally, notable stability was demonstrated in the presence of reducing and chaotropic agents as well as in surfactants, oxidizing agents, and organic solvents commonly found in detergent compositions. This highlights the enzyme’s potential as a versatile biocatalyst, especially in detergents. Its stability and compatibility with laundry detergents matched Alcalase 2.5 L, type Dx, and the Stearothermophilus protease, used as controls. Collectively, this study investigated the potential utilization of S. aureus Pr in industrial detergents as an excellent candidate for incorporation as an additive in detergent formulations. Full article
(This article belongs to the Special Issue Applications of Catalytic Reactions in Promoting the Health of Organisms)
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<p>The effect of incubation time on <span class="html-italic">S. aureus Pr</span> production at different times. (<b>A</b>) The total protease activity in the total fermentation volume (100 mL) and (<b>B</b>) protease activity (U/mg of biomass) at different times during 72 h. The means of three replicates are represented with their corresponding SD (±).</p> Full article ">Figure 2
<p>The effect of temperature and pH on <span class="html-italic">S. aureus</span> protease production. The cultures were incubated at several temperatures ranging from 30 to 60 °C (<b>A</b>) or different initial pH values of the medium (<b>B</b>). The means of three replicates are represented with their corresponding SD (±).</p> Full article ">Figure 3
<p>The extracellular protease production by <span class="html-italic">S. aureus</span> strain and bacterial dry weight of biomass using different carbon sources (<b>A</b>) (at a 5% concentration) and (<b>B</b>) a nitrogen source (at a 1% concentration). The variation in protease activity and bacterial dry weight of biomass is shown with varying concentrations of the most effective carbon (<b>C</b>) and nitrogen (<b>D</b>) sources. The means of three replicates are represented with their corresponding SD (±).</p> Full article ">Figure 4
<p>(<b>A</b>) Chromatography profile of <span class="html-italic">S. aureus Pr</span> on a Mono Q-Sepharose column. (<b>B</b>) SDS-PAGE analysis and (<b>C</b>) MALDI-TOF spectrum of <span class="html-italic">S. aureus Pr</span>, 1: size marquer, 2: purified <span class="html-italic">S. aureus Pr</span>.</p> Full article ">Figure 5
<p>Evaluation of pH and temperature effects on the activity and the stability of <span class="html-italic">S. aureus Pr.</span> (<b>A</b>) The variation of protease activity with a variation of temperature from 40 to 80 °C. The enzymatic activity was measured during 30 min without Ca<sup>2+</sup> and with 3 mM of Ca<sup>2+</sup>. (<b>B</b>) The stability of <span class="html-italic">S. aureus Pr</span> at different temperatures during 30, 60, and 120 min in the absence and in the presence of Ca<sup>2+</sup>. (<b>C</b>) The effect of acidic and alkali pH on <span class="html-italic">S. aureus Pr</span> activity. (<b>D</b>) The stability of <span class="html-italic">S. aureus Pr</span> with a pH variation from 2.0 to 13.0 during 30, 60, and 120 min. The means of three replicates are represented with their corresponding SD (±).</p> Full article ">Figure 6
<p>The effect of stabilizer addition on <span class="html-italic">S. aureus Pr</span> thermal stability enhancement. The residual activity was measured after incubation of <span class="html-italic">S. aureus Pr</span> with 10% of different stabilizer additives (PEG 1500, PEG 6000, glycerol, sorbitol, xylitol, and mannitol) at 90° C during a period of 1 h. The means of three replicates are represented with their corresponding SD (±).</p> Full article ">Figure 7
<p>The impact of oxidizing agents (<b>A</b>), surfactants (<b>B</b>), and organic solvents (<b>C</b>) on <span class="html-italic">S. aureus Pr</span> stability. The residual activity was measured at the optimal condition after incubation of the purified protease with each appropriate agent for 1 h. The commercial Alcalase 2.5 L and <span class="html-italic">Ba.St.Pr</span> were taken as positive controls. The means of three replicates are represented with their corresponding SD (±).</p> Full article ">Figure 8
<p>The stability and compatibility of <span class="html-italic">S. aureus Pr</span> with solid (<b>A</b>) and liquid (<b>B</b>) commercial laundry detergents assessed in comparison to commercial Alcalase 2.5 L and <span class="html-italic">Ba.St.Pr.</span> Residual activities were measured under the same optimal conditions. The means of three replicates are represented with their corresponding.</p> Full article ">
12 pages, 3028 KiB  
Article
Mixed Oxides as Catalysts for the Condensation of Cyclohexanol and Benzaldehyde to Obtain a Claisen–Schmidt Condensation Product
by Tanya Stoylkova, Tsveta Stanimirova, Christo D. Chanev, Petya Petrova and Kristina Metodieva
Catalysts 2024, 14(7), 445; https://doi.org/10.3390/catal14070445 - 11 Jul 2024
Viewed by 556
Abstract
Acid–base M2+MgAlO and M2+AlO mixed oxides (where M2+ = Mg, Cu, Co, Zn, and Ni) were obtained by thermal decomposition of the corresponding layered double hydroxide (LDH) precursors and used as catalysts for cyclohexanol and benzaldehyde condensation under [...] Read more.
Acid–base M2+MgAlO and M2+AlO mixed oxides (where M2+ = Mg, Cu, Co, Zn, and Ni) were obtained by thermal decomposition of the corresponding layered double hydroxide (LDH) precursors and used as catalysts for cyclohexanol and benzaldehyde condensation under solvent-free conditions. The catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and temperature-programmed desorption of CO2 (TPD-CO2). Gas chromatography–mass spectroscopy (GC/MS) was used for the identification and quantification of the product mixtures. In the reaction of cyclohexanol and benzaldehyde on M2+MgAlO and MgAlO catalysts, a 2,6-dibenzylidene-cyclohexanone was obtained as the main product as a result of consecutive one-pot dehydrogenation of cyclohexanol to cyclohexanone and subsequent Claisen–Schmidt condensation. In the reaction mixture obtained in the presence of NiAlO, CoAlO, and ZnAlO catalysts, a cyclohexyl ester of 6-hydroxyhexanoic acid was detected together with the main product. This is most likely a by-product obtained after the oxidation, ring opening, and subsequent esterification of the cyclohexanol. Full article
(This article belongs to the Special Issue Layered Double Hydroxide-Based Catalysts for Advanced Chemical Technologies)
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<p>XRD patterns and SEM photographs of initial M<sup>2+</sup>MgAl LDH (<b>a</b>) and corresponding forms calcined at 500 °C (<b>b</b>).</p> Full article ">Figure 2
<p>XRD patterns and SEM photographs of initial M<sup>2+</sup>l LDH (<b>a</b>) and corresponding calcined forms (<b>b</b>).</p> Full article ">Figure 3
<p>TPD-CO<sub>2</sub> profiles of the mixed-oxide catalysts. (<b>A</b>)—CuMgAlO (a), CoMgAlO (b), ZnMgAlO (c), NiMgAlO (d); (<b>B</b>)—MgAlO (e), CoAlO (f), ZnAlO (g), NiAlO (h).</p> Full article ">Figure 4
<p>Cyclohexanol conversion and yields of the 2,6-dibenzylidene-cyclohexanon; reaction temperature 150 °C and reaction time 2 h.</p> Full article ">Figure 5
<p>The cyclohexanol conversion vs. total number of base sites for used catalysts; reaction temperature 150 °C and reaction time 2 h.</p> Full article ">Scheme 1
<p>The possible reaction mechanism for (<b>A</b>) dehydrogenation of cyclohexanol to cyclohexanone over acid–base centers; (<b>B</b>) the base-catalyzed C-C coupling of cyclohexanone and benzaldehyde to the Claisen–Schmidt condensation product.</p> Full article ">Scheme 2
<p>Possible reaction route for oxidation of cyclohexanol.</p> Full article ">
4 pages, 164 KiB  
Editorial
Nanocatalysts for the Degradation of Refractory Pollutants
by Sheng Guo, Yazi Liu and Jun Li
Catalysts 2024, 14(7), 444; https://doi.org/10.3390/catal14070444 - 11 Jul 2024
Viewed by 479
Abstract
The rapid development of industrialization has resulted in the excessive emission of hazardous contaminants into our water and air resources, adversely affecting both health and the environment [...] Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
16 pages, 17079 KiB  
Article
Structural Effect of Cu-Mn/Al2O3 Catalysts on Enhancing Toluene Combustion Performance: Molecular Structure of Polyols and Hydrothermal Treatment
by Junjie Li, Wenjing Chen, Chenghua Xu, Xiaoxiao Hou and Xiaodong Hu
Catalysts 2024, 14(7), 443; https://doi.org/10.3390/catal14070443 - 11 Jul 2024
Viewed by 493
Abstract
This study presents a series of Cu-Mn/Al2O3 catalysts prepared by the polyol method to improve the toluene combustion process. The catalytic activity evaluation results showed that the different polyols have a great influence on catalyst activity, in which the catalyst [...] Read more.
This study presents a series of Cu-Mn/Al2O3 catalysts prepared by the polyol method to improve the toluene combustion process. The catalytic activity evaluation results showed that the different polyols have a great influence on catalyst activity, in which the catalyst prepared with glycerol through a hydrothermal reaction at 90 °C displayed the highest catalytic activity. The lowest T90 and T50 values could be achieved by CMA-GL-90 with 260 and 237 °C, respectively. Moreover, the XRD and BET results showed that the hydrothermal treatment was more favorable with Cu-Mn crystal formation, and an abundance of mesopores remained in all catalysts with a high specific surface area from 94.37 to 123.03 m2·g−1. The morphology analysis results by SEM and TEM indicated that employing glycerol coupled with hydrothermal treatment at 90 °C could enhance the formation of CuMn2O4 spinel. The toluene catalytic combustion mechanism of Cu-Mn/Al2O3 catalysts was discussed based on XPS and H2-TPR, and a high atomic ratio of Mn3+ could be obtained with 51.03%, and the ratio of Oads/Olatt also increased to 2.85 in CMA-GL-90. The increase in Mn3+ species and oxygen vacancies on the surface of catalysts exhibited excellent activity and stability for toluene combustion. These findings offer valuable insights for optimizing the design and application of Cu-Mn/Al2O3 catalysts in addressing the catalytic oxidation reactions of organic volatile compounds. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis and Advanced Oxidation Processes (AOP) for Environmental Protection (VOCs Oxidation, Air and Water Purification), 2nd Edition)
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<p>Catalytic combustion performance of toluene on the different types of catalysts treated by aging at room temperature (<b>a</b>) or by the hydrothermal reaction (<b>b</b>), and the toluene conversion (<b>c</b>) and the surface area normalized reaction rates (<b>d</b>) of CMA-GL-90 and CMA-GL-RT. (Reaction condition: toluene concentration = 500 ppm and GHSV = 10,000 h<sup>−1</sup>).</p> Full article ">Figure 2
<p>XRD patterns of Cu-Mn/Al<sub>2</sub>O<sub>3</sub> catalysts prepared in different crystallization systems (<b>a</b>) by aging at room temperature and (<b>b</b>) by the hydrothermal reaction.</p> Full article ">Figure 3
<p>N<sub>2</sub> adsorption–desorption isotherms of Cu-Mn Cu-Mn/Al<sub>2</sub>O<sub>3</sub> catalysts. (Blank line: adsorption curve and red line: desorption curve).</p> Full article ">Figure 4
<p>SEM image of Cu-Mn/Al<sub>2</sub>O<sub>3</sub> catalysts prepared in different crystallization systems: (<b>a</b>–<b>d</b>) in GL, BDO, PDO, and EG by aging at room temperature, respectively, and (<b>e</b>–<b>h</b>) in GL, BDO, PDO and EG by the hydrothermal reaction, respectively.</p> Full article ">Figure 5
<p>TEM image of Cu-Mn/Al<sub>2</sub>O<sub>3</sub> catalysts prepared in different crystallization systems: (<b>a</b>–<b>d</b>) in GL, BDO, PDO, and EG by aging at room temperature, respectively, and (<b>e</b>–<b>h</b>) in GL, BDO, PDO, and EG by the hydrothermal reaction, respectively.</p> Full article ">Figure 6
<p>HRTEM and SAED images of Cu-Mn/Al<sub>2</sub>O<sub>3</sub> catalysts prepared in GL by aging at room temperature (<b>a</b>–<b>c</b>) and by the hydrothermal reaction (<b>d</b>–<b>f</b>).</p> Full article ">Figure 7
<p>Mn 2p<sub>3/2</sub>XPS spectra of the catalysts prepared by aging at room temperature (<b>a</b>) and the hydrothermal reaction (<b>b</b>).</p> Full article ">Figure 8
<p>Cu 2p<sub>3/2</sub>XPS spectra of the catalysts prepared by aging at room temperature (<b>a</b>) and the hydrothermal reaction (<b>b</b>).</p> Full article ">Figure 9
<p>O1s XPS spectra of the catalysts prepared by aging at room temperature (<b>a</b>) and the hydrothermal reaction (<b>b</b>).</p> Full article ">Figure 10
<p>H<sub>2</sub>-TPR profiles of CMA catalyst prepared by aging at room temperature (<b>a</b>) and the hydrothermal reaction (<b>b</b>).</p> Full article ">Figure 11
<p>Toluene conversion as a function of on-stream reaction time over CMA-GL-90 and CMA-PDO-90.</p> Full article ">Scheme 1
<p>The catalytic combustion mechanism of toluene on the catalyst.</p> Full article ">
15 pages, 9817 KiB  
Article
Enhanced Photocatalytic Performances of SnS2/TiO2 Composites via a Charge Separation Following Z-Scheme at the SnS2/TiO2{101} Facets
by Nkenku Carl, Muhammad Fiaz, Hyun-Seok Oh and Yu-Kwon Kim
Catalysts 2024, 14(7), 442; https://doi.org/10.3390/catal14070442 - 10 Jul 2024
Cited by 1 | Viewed by 1000
Abstract
The formation of heterojunctions for efficient charge separation has been practiced for the preparation of efficient semiconductor-based photocatalysts for applications such as hydrogen production and environmental remediation. In this study, we synthesized a composite structure with a heterojunction between SnS2 and TiO [...] Read more.
The formation of heterojunctions for efficient charge separation has been practiced for the preparation of efficient semiconductor-based photocatalysts for applications such as hydrogen production and environmental remediation. In this study, we synthesized a composite structure with a heterojunction between SnS2 and TiO2 through a microwave-assisted hydrothermal process, in which SnS2 nanoparticles grew on nanocrystalline TiO2 nanosheets preferentially at the exposed {101} facets. Appropriate exposure of the {001} and {101} facets of the TiO2 nanosheet in the composite with a preferential growth of SnS2 nanoparticles at the {101} facets was the origin of the charge separation following a direct Z-scheme mechanism to result in enhanced photocatalytic performances in photodegradation of organic dyes such as methylene blue (MB) and rhodamine B (RhB) compared to that of SnS2 and TiO2 alone. A plot of photodegradation rates vs. SnS2 ratios in the composites gave an overall volcano-shaped curve with a maximum at the SnS2 ratio of about 33% at which small SnS2 nanoparticles were populated at the {101} facets of the TiO2 nanosheets with a high surface area (118.2 m2g−1). Our results suggest the microwave-assisted hydrothermal process can be a good synthetic approach for composite-based photocatalysts with a preferential heterojunction structure. Full article
(This article belongs to the Special Issue Recent Advances in Environment and Energy Catalysis)
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<p>XRD patterns of selected SnS<sub>2</sub>/TiO<sub>2</sub> composites in comparison with those of as-prepared SnS<sub>2</sub> and TiO<sub>2</sub>.</p> Full article ">Figure 2
<p>Bandgap of the composites as a function of %SnS<sub>2</sub>. Also shown in the inset are the absorbance spectra of the composites.</p> Full article ">Figure 3
<p>SEM images of (<b>a</b>) TiO<sub>2</sub> nanosheets, (<b>b</b>–<b>e</b>) SnS<sub>2</sub>/TiO<sub>2</sub> composites with the %SnS<sub>2</sub> ratio of 9–75%, and (<b>f</b>) SnS<sub>2</sub> nanoparticles.</p> Full article ">Figure 4
<p>TEM images of TiO<sub>2</sub> nanosheets (<b>a</b>,<b>b</b>), SnS<sub>2</sub> nanoparticles (<b>c</b>,<b>d</b>), and SnS<sub>2</sub>/TiO<sub>2</sub> composites with a SnS<sub>2</sub> ratio of 33% (<b>e</b>) and 43% (<b>f</b>).</p> Full article ">Figure 5
<p>Raman spectra of SnS<sub>2</sub>/TiO<sub>2</sub> composites in comparison with those of as-synthesis TiO<sub>2</sub> nanosheets and SnS<sub>2</sub> nanoparticles.</p> Full article ">Figure 6
<p>(<b>a</b>) PL spectra for SnS<sub>2</sub>/TiO<sub>2</sub> composites with the excitation of a 325 nm laser, (<b>b</b>) the plot of maximum PL intensities at wavelengths of 520–550 nm as a function of % SnS<sub>2</sub>, and (<b>c</b>) the plot of the difference between the dashed line (<a href="#catalysts-14-00442-f006" class="html-fig">Figure 6</a>b) and the actual emission.</p> Full article ">Figure 7
<p>(<b>a</b>) O 1s, (<b>b</b>) Ti 2p, (<b>c</b>) S 2p, and (<b>d</b>) Sn 3d core-level spectra of the SnS<sub>2</sub>/TiO<sub>2</sub> composite (%SnS<sub>2</sub> = 33%) in comparison with those of SnS<sub>2</sub> and TiO<sub>2</sub>.</p> Full article ">Figure 8
<p>Photodegradation rates are shown as plots of C/Co vs. irradiation time for (<b>a</b>) MB and (<b>c</b>) RhB, along with initial rate constants vs. %SnS<sub>2</sub> in the composites for (<b>b</b>) MB and (<b>d</b>) RhB.</p> Full article ">Figure 9
<p>Comparison of rate constants with the use of trapping agents for (<b>a</b>) MB (SnS<sub>2</sub>/TiO<sub>2</sub> 29%) and (<b>b</b>) RhB (SnS<sub>2</sub>/TiO<sub>2</sub> 33%).</p> Full article ">Figure 10
<p>Energy diagram of the valence band (VB) and conduction band (CB) of the SnS<sub>2</sub>/TiO<sub>2</sub> composite and a plausible mechanism for the charge separation and the generation of radical species. (<b>a</b>) Band alignment diagram for the SnS<sub>2</sub>/TiO<sub>2</sub> and (<b>b</b>) Proposed charge separation mechanism at the heterojunction via Z-scheme. The energy levels for the CB (E<sub>CB</sub>) and the VB (E<sub>VB</sub>) can be calculated following <a href="#app1-catalysts-14-00442" class="html-app">Equations (S1) and (S2) listed in the Supplementary Materials</a>.</p> Full article ">Scheme 1
<p>The schematic diagram for the synthesis of SnS<sub>2</sub>/TiO<sub>2</sub> heterojunction.</p> Full article ">
11 pages, 2358 KiB  
Article
Tuning a Cr-Catalyzed Ethylene Oligomerization Product Profile via a Rational Design of the N-aryl PNP Ligands
by Samir Barman, E. A. Jaseer, Nestor Garcia, Mohamed Elanany, Motaz Khawaji, Niladri Maity and Abdulrahman Musa
Catalysts 2024, 14(7), 441; https://doi.org/10.3390/catal14070441 - 10 Jul 2024
Viewed by 618
Abstract
An approach towards incorporating varied degrees of steric profiles around the ligand’s backbone, which were envisaged to alter the catalytic paths leading to targeted 1-C8/1-C6 olefin products, were explored. Cr-pre-catalysts designed with PNP ligands comprising a fused aryl moiety were [...] Read more.
An approach towards incorporating varied degrees of steric profiles around the ligand’s backbone, which were envisaged to alter the catalytic paths leading to targeted 1-C8/1-C6 olefin products, were explored. Cr-pre-catalysts designed with PNP ligands comprising a fused aryl moiety were delivered at a relatively higher C8 olefin selectivity (up to 74.6 wt% and C8/C6 of 3.4) when the N-connection to the aromatic unit was placed at the 2-position. A relatively higher C6 olefin selectivity (up to 33.7 wt% and C8/C6 of 1.9) was achieved with the PNP unit anchored at the 1- or 6-position. Based on detailed catalytic studies, we confirm the fact that by introducing a controlled degree of bulkiness on the N-site through a judicious selection of the N-aryl moiety of different sizes, the selectivity of the targeted olefin product could be tuned in a rational manner. Full article
(This article belongs to the Special Issue Advanced Catalysis for Energy and Environmental Applications)
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Figure 1

Figure 1
<p>Various N-aryl functionalized PNP ligands evaluated for selective ethylene oligomerization.</p> Full article ">Figure 2
<p>The liquid stare <sup>31</sup>P NMR spectra of ligand <b>1</b> (<b>left</b>) and <b>2</b> (<b>right</b>).</p> Full article ">Figure 3
<p>Illustration of a common underlying basic substructure around PNP units in ligands <b>1</b>, <b>3</b>, and <b>5</b> is schematically depicted (highlighted in red). Similarly, ligands <b>2</b>, <b>4</b>, <b>6</b>, and <b>7</b> are expected to showcase somewhat identical steric profiles around the PNP units, as illustrated in blue. In contrast, ligands <b>8</b> and <b>9</b> were assumed to introduce a slightly altered steric environment.</p> Full article ">Figure 4
<p>The influence of PNP connectivity to the aryl ring dictates the reaction pathways, leading to the preferential formation of 1-octene product over 1-C<sub>6</sub> olefin.</p> Full article ">Scheme 1
<p>Synthetic scheme for the preparation of N-anthracenyl-substituted PNP ligand <b>1</b>.</p> Full article ">Scheme 2
<p>Synthetic scheme for the preparation of N-pyrenyl-substituted PNP ligand <b>2</b>.</p> Full article ">Scheme 3
<p>Synthetic scheme for the preparation of N-napthyl-substituted PNP ligand <b>3</b>.</p> Full article ">Scheme 4
<p>Synthetic scheme for the preparation of ligand <b>4</b>.</p> Full article ">Scheme 5
<p>Synthetic scheme for the preparation of ligand <b>9</b>.</p> Full article ">Scheme 6
<p>Synthetic scheme for the preparation of ligand <b>7</b>.</p> Full article ">Scheme 7
<p>Synthetic scheme for the preparation of ligand <b>8</b>.</p> Full article ">
11 pages, 2861 KiB  
Article
Theoretical Study of Reversible Hydrogenation of CO2 to Formate Catalyzed by Ru(II)–PN5P, Fe(II)–PN5P, and Mn(I)–PN5P Complexes: The Effect of the Transition Metal Center
by Lingqiang Meng, Lihua Yao and Jun Li
Catalysts 2024, 14(7), 440; https://doi.org/10.3390/catal14070440 - 9 Jul 2024
Viewed by 643
Abstract
In 2022, Beller and coworkers achieved the reversible hydrogenation of CO2 to formic acid using a Mn(I)–PN5P complex with excellent activity and reusability of the catalyst. To understand the detailed mechanism for the reversible hydrogen release–storage process, especially the effects [...] Read more.
In 2022, Beller and coworkers achieved the reversible hydrogenation of CO2 to formic acid using a Mn(I)–PN5P complex with excellent activity and reusability of the catalyst. To understand the detailed mechanism for the reversible hydrogen release–storage process, especially the effects of the transition metal center in this process, we employed DFT calculations according to which Ru(II) and Fe(II) are considered as two alternatives to the Mn(I) center. Our computational results showed that the production of formic acid from CO2 hydrogenation is not thermodynamically favorable. The reversible hydrogen release–storage process actually occurs between CO2/H2 and formate rather than formic acid. Moreover, Mn(I) might not be a unique active metal for the reversible hydrogenation of CO2 to formate; Ru(II) would be a better option. Full article
(This article belongs to the Special Issue Catalysis for Selective Hydrogenation of CO and CO2, 2nd Edition)
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Figure 1

Figure 1
<p>The optimized geometries of all species in CO<sub>2</sub> hydrogenation to formic acid catalyzed by the Ru(II)–PN<sup>5</sup>P complex. The R<sub>1</sub> groups in <b>TS4/5</b> and complex <b>5</b> are omitted for clarity. The bond distances are in angstrom (Å), and the bond angles are in degrees (◦). (Ru: pink; C: cyan; P: orange; O: red; N: blue; H: white).</p> Full article ">Figure 2
<p>Free energy profile for CO<sub>2</sub> hydrogenation to formic acid catalyzed by Mn(I)–PN<sup>5</sup>P, Fe(II)–PN<sup>5</sup>P, and Ru(II)–PN<sup>5</sup>P complexes.</p> Full article ">Figure 3
<p>The optimized geometries of selected species in the regeneration of the Ru(II)–PN<sup>5</sup>P complex. The R<sub>1</sub> groups in the <b>TS7/1</b> and <b>TS8/9</b> are omitted for clarity. The distances are angstrom (Å) (Ru: pink; C: cyan; P: orange; O: red; N: blue; H: white).</p> Full article ">Figure 4
<p>Free energy profile for the regeneration of Mn(I)–PN<sup>5</sup>P, Fe(II)–PN<sup>5</sup>P, and Ru(II)–PN<sup>5</sup>P complexes.</p> Full article ">Figure 5
<p>Free energy profile for the reversible hydrogen storage–release catalyzed by Mn(I)–PN<sup>5</sup>P, Fe(II)–PN<sup>5</sup>P, and Ru(II)–PN<sup>5</sup>P complexes.</p> Full article ">Scheme 1
<p>Mn(I)–PN<sup>5</sup>P, Fe(II)–PN<sup>5</sup>P, and Ru(II)–PN<sup>5</sup>P complexes considered in this work (P = P<span class="html-italic"><sup>i</sup></span>Pr<sub>2</sub>; R = NH–C<sub>3</sub>H<sub>5</sub>).</p> Full article ">Scheme 2
<p>Proposed mechanism for CO<sub>2</sub> hydrogenation to formic acid (P = P<span class="html-italic"><sup>i</sup></span>Pr<sub>2</sub>, R<sub>1</sub> = NH–C<sub>3</sub>H<sub>5</sub>; M = Ru, Fe, R<sub>2</sub> = H; M = Mn, R<sub>2</sub> = CO).</p> Full article ">Scheme 3
<p>The pathway for the regeneration of catalysts (P = P<span class="html-italic"><sup>i</sup></span>Pr<sub>2</sub>, R<sub>1</sub> = NH–C<sub>3</sub>H<sub>5</sub>; M = Ru, Fe, R<sub>2</sub> = H; M = Mn, R<sub>2</sub> = CO).</p> Full article ">
2 pages, 153 KiB  
Editorial
Exclusive Review Papers in Catalytic Materials
by Carolina Belver
Catalysts 2024, 14(7), 439; https://doi.org/10.3390/catal14070439 - 9 Jul 2024
Viewed by 457
Abstract
Catalytic materials exist in several forms and can be prepared using different methodologies and protocols [...] Full article
(This article belongs to the Special Issue Exclusive Review Papers in Catalytic Materials)
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