CN108339522A - A kind of amino acid@Cu-BTC compound adsorbents and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of adsorption materials, and discloses an amino acid@Cu-BTC composite adsorbent and a preparation method thereof. Add nano-ZnO to deionized water, add DMF after ultrasonic dispersion to obtain ZnO nano-slurry solution; dissolve Cu(NO ₃ ) ₂ 3H ₂ O and amino acid in deionized water to obtain Cu(NO ₃ ) ₂ mixed with amino acid solution; Trimellitic acid is dissolved in ethanol to obtain a Trimellitic acid solution; Cu(NO ₃ ) ₂ and amino acid mixed solution are added to the ZnO nano-slurry solution, stirred and mixed evenly, and then added Trimellitic acid solution for reaction , the resulting solid product was activated by vacuum to obtain the amino acid@Cu‑BTC composite adsorbent. The amino acid@Cu‑BTC composite adsorbent prepared by the present invention has excellent water vapor stability and high _CO2 adsorption capacity at the same time.

Description

A kind of amino acid@Cu-BTC composite adsorbent and its preparation method

technical field

The invention belongs to the technical field of adsorption materials, and in particular relates to an amino acid@Cu-BTC composite adsorbent and a preparation method thereof.

Background technique

With the development of global industrialization, a large amount of _CO2 is emitted into the atmosphere, causing environmental problems such as the greenhouse effect, global climate anomalies, sea level rise, frequent natural disasters and land desertification, which have great impact on the survival of human beings and the development of society around the world have had serious effects. Therefore, effective capture of CO ₂ and reduction of its emission have become one of the hot topics of current scholars' research. At present, the technologies that can be used to capture CO ₂ mainly include cryogenic distillation, membrane separation, chemical absorption, physical adsorption, and catalytic combustion. The physical adsorption method is considered to be the most promising new separation method for industrial applications because it can be separated under normal temperature and pressure conditions, which is more energy-saving and efficient.

The adsorbent is the key in the adsorption separation method, and its performance will determine the efficiency and energy consumption of the separation process. At present, the adsorbents that can be applied to _CO2 capture mainly include traditional adsorbents such as zeolites and activated carbons and emerging porous materials such as metal-organic frameworks (MOFs), etc. Compared with traditional adsorbents, metal-organic framework materials (MOFs) have a larger specific surface area and higher porosity, and have the characteristics of adjustable pores and easy surface functional modification. has a good application prospect. Among them, Cu-BTC (also known as: HKUST-1) is one of the MOFs materials with excellent adsorption properties for gases under normal temperature and pressure conditions. Aprea et al. reported that the adsorption capacity of Cu-BTC to _CO2 was as high as 7.0mmol/g at 283K and 1bar (P Aprea., D Caputo., N Gargiulo., et al. Modeling CarbonDioxide Adsorption on Microporous Substrates Comparison between Cu-BTC Metal-Organic Framework and 13X Zeolitic Molecular Sieve[J].J Chem Eng Data,2010,55(9):3655-3661), is currently recognized as one of the best MOF materials for _CO2 adsorption at low pressure; in addition , Cu-BTC also exhibited good adsorption properties for VOCs and ethylene/ethane. The adsorption performance of Cu-BTC is much higher than that of traditional activated carbon, molecular sieve and silica gel adsorption materials. However, in practical applications, water vapor is ubiquitous, and the water vapor stability of Cu-BTC is very poor. Once exposed to a humid environment, due to the attack of water molecules, the Cu-O bond in Cu-BTC will break, resulting in the collapse of the structure (NC Burtch, H. Jasuja, KS Walton, Water stability and adsorption in metal-organic frameworks[ J], Chem Rev, 114 (2014) 10575-10612). Therefore, how to enhance the water vapor stability of Cu-BTC has become one of the hot topics studied by many scholars. Zhang et al. used the vapor deposition technique to coat the surface of Cu-BTC with hydrophobic silane at 235°C (W. Zhang, Y. Hu, J. Ge, HL Jiang, SHYu, A facile and general coating approach to moisture/water-resistant metal-organic frameworks with intact porosity, Journal of the American Chemical Society, 136 (2014) 16978-16981), after the material modified by PDMS was in contact with the air of 55% relative humidity for 1 day, it still kept good stability, but no adsorption properties were reported. Al-Janabi et al. applied the post-synthesis modification method to graft glycine onto Cu-BTC, and found that the adsorption capacity of the prepared material for CO ₂ at normal pressure dropped to only 2.2mmol/g, Also lower than general carbon materials and molecular sieves (N.Al-Janabi, H.Deng, J.Borges, X.Liu, A.Garforth, FR Siperstein, X.Fan, A Facile Post-Synthetic Modification Method To Improve Hydrothermal Stability and CO2Selectivity of CuBTC Metal–Organic Framework, Industrial & Engineering Chemistry Research, 55(2016) 7941-7949.). Li Yujie et al. used a mechanical method to prepare Cu-BTC@GO, a composite material of Cu-BTC and graphite oxide. After soaking in water for 10 hours, the composite material still had a BET specific surface area as high as 1000m ² /g, and the water stability was greatly improved ( Y.Li, J.Miao, X.Sun, J.Xiao, Y.Li, H.Wang, Q.Xia, Z.Li, Mechanochemical synthesis of Cu-BTC@GO with enhanced water stability and toluene adsorption capacity[J], Chemical Engineering Journal. 2016, 298:191-7). Therefore, the development of an adsorbent material with higher water vapor stability and enhanced _CO2 adsorption performance will have a better application prospect in adsorption separation.

Contents of the invention

In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing an amino acid@Cu-BTC composite adsorbent.

Another object of the present invention is to provide an amino acid@Cu-BTC composite adsorbent prepared by the above method.

The object of the invention is achieved through the following technical solutions:

A preparation method of amino acid@Cu-BTC composite adsorbent, comprising the following preparation steps:

(1) Add nano-ZnO into deionized water, add N,N-dimethylformamide (DMF) after ultrasonic dispersion, and obtain ZnO nano-slurry solution; dissolve Cu(NO ₃ ) ₂ ·3H ₂ O and amino acid in In deionized water, a mixture of Cu(NO ₃ ) ₂ and amino acids is obtained; by dissolving trimesic acid in ethanol, a solution of trimesic acid is obtained;

(2) Add the Cu(NO ₃ ) ₂ and amino acid mixed solution obtained in step (1) into the ZnO nano slurry solution, stir and mix evenly, then add the trimesic acid solution, and stir for 5-10 minutes to obtain the reaction product. The reaction solution was filtered, and the solid product was sequentially soaked in methanol, centrifuged and dried to obtain a blue solid powder;

(3) Vacuum-activate the solid powder obtained in step (2) to obtain amino acid@Cu-BTC composite adsorbent.

Preferably, the molar ratio of ZnO to Cu(NO ₃ ) ₂ ·3H ₂ O in step (1) is 1:(1.25˜2).

Preferably, the amino acid in step (1) refers to glycine (Gly), β-alanine (β-Ala) or γ-aminobutyric acid (GABA).

Preferably, the volume ratio of the total amount of deionized water:DMF:ethanol in step (1) is (1-1.1):(1-1.2):(1-1.3).

Preferably, the molar ratio of Cu(NO ₃ ) ₂ ·3H ₂ O to amino acid in step (1) is 1:(0.2-0.5).

Preferably, the filtering in step (2) refers to filtering with an organic membrane with an average pore size of 0.45 μm.

Preferably, the drying in step (2) refers to drying at 60-80° C. for 4-8 hours.

Preferably, the vacuum activation in step (3) refers to vacuum activation at 120-150° C. for 8-16 hours.

An amino acid@Cu-BTC composite adsorbent prepared by the above method.

The preparation method of the present invention and the resulting product have the following advantages and beneficial effects:

(1) The preparation method of the present invention is simple to operate, easy to realize, and has good repeatability; the synthesis reaction can be carried out under normal temperature conditions, the reaction time is short, and it only takes 5 to 10 minutes to complete the entire synthesis reaction, while the traditional hydrothermal method synthesizes Cu-BTC It takes 1 to 2 days to react at 160°C.

(2) Compared with the existing Cu-BTC adsorbent materials, the amino acid@Cu-BTC composite adsorbent prepared in the present invention has excellent water vapor stability and high _CO2 adsorption capacity at the same time.

Description of drawings

Fig. 1 is the _N2 adsorption-desorption isotherm diagram of Cu-BTC and the amino acid@Cu-BTC material obtained in each embodiment.

Fig. 2 is the XRD spectrum of Cu-BTC and the amino acid@Cu-BTC material obtained in each embodiment.

Fig. 3 is the SEM image of Cu-BTC and the amino acid@Cu-BTC material obtained in each embodiment.

Fig. 4 is the _CO2 adsorption isotherm diagram of Cu-BTC and the amino acid@Cu-BTC material obtained in each embodiment.

Fig. 5 is the XRD pattern of Cu-BTC and Gly@Cu-BTC obtained in Example 1 at RH=50% after standing for 20 days.

Fig. 6 is a graph showing the change of CO ₂ adsorption measured under the conditions of 298K and 1 bar after Cu-BTC and Gly@Cu-BTC obtained in Example 1 were placed in an environment of RH=50% for different days.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

(1) Dissolve nano-ZnO (3.6mmol, n ₁ ) in deionized water (8ml, n ₂ ), and add DMF (16ml, n ₃ ) after ultrasonic dispersion for 10min to obtain ZnO nano-slurry solution; Cu(NO ₃ ) ₂ 3H ₂ O (7.2mmol, n ₄ ) and Gly (2.16mmol, n ₅ ) were dissolved in deionized water (8ml, n ₆ ) to obtain Cu(NO ₃ ) ₂ and Gly mixed solution; (3.2mmol, n ₇ ) was dissolved in ethanol (16ml, n ₈ ) to obtain a trimesic acid solution; the ratio of the various substances used was (n ₂ +n ₆ ):n ₃ :n ₈ =1:1 :1; n ₁ :n ₄ =1:2.

(2) Add the Cu(NO ₃ ) ₂ and Gly mixed solution obtained in step (1) into the ZnO nano-slurry solution, stir and mix evenly, then add the trimesic acid solution, stir and react for 5-10 minutes to obtain the reaction product containing For the blue solution, the solution is filtered with an organic filter membrane with an average pore size of 0.45 μm, and the solid product is sequentially soaked in methanol, centrifuged and dried to obtain a blue solid powder.

(3) The solid powder obtained in step (2) was placed at 120°C for vacuum activation for 12 hours to obtain a glycine@Cu-BTC solid powder, which was denoted as Gly@Cu-BTC material.

Example 2

(1) Dissolve nano-ZnO (5.76mmol, n ₁ ) in deionized water (8ml, n ₂ ), and add DMF (19ml, n ₃ ) after ultrasonic dispersion for 10min to obtain ZnO nano-slurry solution; Cu(NO ₃ ) ₂ · 3H ₂ O (7.2mmol, n ₄ ) and β-Ala (2.88mmol, n ₅ ) were dissolved in deionized water (8ml.n ₆ ) to obtain a mixed solution of Cu(NO ₃ ) ₂ and β-Ala; Trimellitic acid (3.2mmol, n ₇ ) was dissolved in ethanol (16ml, n ₈ ) to obtain a trimesic acid solution; the dosage ratio of various substances was (n ₂ +n ₆ ):n ₃ :n ₈ =1:1.2:1; n1:n4=1:1.25.

(2) Add the mixed solution of Cu(NO ₃ ) ₂ and β-Ala obtained in step (1) into the ZnO nano slurry solution, stir and mix evenly, then add the trimesic acid solution, and stir for 5-10 minutes to obtain the reaction mixture containing For the blue solution of the product, the solution is filtered through an organic filter membrane with an average pore size of 0.45 μm, and the solid product is sequentially soaked in methanol, centrifuged and dried to obtain a blue solid powder.

(3) Put the solid powder obtained in step (2) at 120°C for vacuum activation for 16 hours to obtain β-alanine@Cu-BTC solid powder, which is designated as Ala@Cu-BTC material.

Example 3

Dissolve nano-ZnO (3.6mmol, n ₁ ) in deionized water (8ml, n ₂ ), ultrasonically disperse for 10min and add DMF (16ml, n ₃ ) to obtain ZnO nano-slurry solution; Cu(NO ₃ ) ₂ ·3H ₂ O (7.2mmol, n ₄ ) and GABA (2.88mmol, n ₅ ) were dissolved in deionized water (8ml, n ₆ ) to obtain Cu(NO ₃ ) ₂ and GABA mixed solution; Trimellitic acid (3.2mmol ,n ₇ ) was dissolved in ethanol (21ml,n ₈ ) to obtain trimesic acid solution; wherein the dosage ratio of various substances was (n ₂ +n ₆ ):n ₃ :n ₈ =1:1:1.3; n ₁ :n ₄ =1:2.

(2) Add the Cu(NO ₃ ) ₂ and GABA mixed solution obtained in step (1) into the nano-slurry ZnO solution, stir and mix evenly, then add trimesic acid solution, stir and react for 5 to 10 minutes to obtain the reaction product containing For the blue solution, the solution is filtered with an organic filter membrane with an average pore size of 0.45 μm, and the solid product is sequentially soaked in methanol, centrifuged and dried to obtain a blue solid powder.

(3) Put the solid powder obtained in step (2) at 150°C for vacuum activation for 8 hours to obtain γ-aminobutyric acid@Cu-BTC solid powder, which is denoted as GABA@Cu-BTC material.

The pore structure of the amino acid@Cu-BTC material prepared in the above examples was characterized by using the ASAP2460 specific surface pore size distribution instrument produced by Micromeritics in the United States. Fig. 1 is the _N2 adsorption-desorption isotherms of the materials prepared in all examples and Cu-BTC at 77K. According to the isotherms, the specific surface area, pore volume and other information of the materials can be calculated, and the obtained structural information is listed in Table 1. . From the results in Figure 1 and Table 1, it can be seen that the BET specific surface area of the amino acid@Cu-BTC material prepared by the present invention is about 1715-1820m ² /g, and the total pore volume is in the range of 0.75-0.80cm ³ /g. This shows that the material prepared by the present invention has a higher specific surface area and a larger pore volume.

Table 1

Fig. 2 is the XRD figure of the material and Cu-BTC prepared by all embodiments, sees from figure, all materials all appear three characteristic diffraction peaks at 2θ=6.8 °, 9.6 ° and 11.8 ° place, these characteristic peaks and literature The reported characteristic diffraction peaks of Cu-BTC are basically consistent (C.Petit, B.Mendoza, T.J.Bandosz, Reactive adsorption of ammonia on Cu-based MOF/graphene composites[J], Langmuir, 26(2010) 15302-15309), It shows that the amino acid @Cu-BTC prepared by the present invention has a crystal structure similar to that of the original Cu-BTC.

Fig. 3 is the SEM picture of the materials prepared in all the examples and the Cu-BTC material, it can be seen from the figure that these materials all have a regular octahedral structure.

Figure 4 is the _CO2 adsorption isotherm graph at 298 K for the materials prepared in all examples and Cu-BTC. It can be seen from the figure that the adsorption capacity of the example material for _CO2 is higher compared with pristine Cu-BTC.

Fig. 5 is an XRD pattern of Cu-BTC and Gly@Cu-BTC prepared in Example 1 placed in an environment of RH=50% for 20 days. It can be seen from the figure that after being placed for 20 days, the XRD characteristic peaks of the original Cu-BTC have basically disappeared, indicating that the structure of Cu-BTC has collapsed; while the Gly@Cu-BTC material prepared in Example 1 was placed for 20 days, Its characteristic peaks remain basically unchanged, indicating that it still has a good crystal structure.

Fig. 6 is a graph showing the change of CO ₂ adsorption measured under the conditions of 298K and 1 bar after Cu-BTC and Gly@Cu-BTC prepared in Example 1 were placed in an environment of RH=50% for different days. As can be seen from the figure, after Cu-BTC was placed for 20 days, its _CO2 adsorption capacity decreased significantly, only 9.12% of fresh Cu-BTC, indicating that the water vapor stability of Cu-BTC was very poor; After the Gly@Cu-BTC material was placed in an environment of RH=50% for 20 days, its CO ₂ adsorption capacity was still 81.48% of the original, indicating that the water vapor stability of the Gly@Cu-BTC material of the present invention was greatly enhanced.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (9)

1. a kind of preparation method of amino acid@Cu-BTC compound adsorbents, it is characterised in that including following preparation process：

(1) nano-ZnO is add to deionized water, DMF is added after ultrasonic disperse, obtain ZnO nano slurry solution；By Cu (NO₃)₂·3H₂O and amino acid are dissolved in deionized water, obtain Cu (NO₃)₂With amino acid mixed liquor；Trimesic acid is molten Solution obtains trimesic acid solution in ethyl alcohol；

(2) Cu (NO for obtaining step (1)₃)₂It is added in ZnO nano slurry solution, is stirred with amino acid mixed liquor It is even, add trimesic acid solution, be stirred to react 5~10min and obtain reaction product, reaction solution is filtered, solid product according to It is secondary to impregnate, centrifuge and dry through methanol, obtain the solid powder of blue；

(3) step (2) obtained solid powder is subjected to vacuum activating, obtains amino acid@Cu-BTC compound adsorbents.

2. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly ZnO described in (1) and Cu (NO₃)₂·3H₂The molar ratio of O is 1:(1.25~2).

3. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly amino acid described in (1) refers to glycine, Beta-alanine or γ-aminobutyric acid.

4. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly deionized water total amount in (1):DMF:The volume ratio of ethyl alcohol is (1~1.1):(1~1.2):(1~1.3).

5. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly Cu (NO described in (1)₃)₂·3H₂The molar ratio of O and amino acid is 1:(0.2~0.5).

6. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly it is 0.45 μm of organic membrane filtration that filtering described in (2), which refers to average pore size,.

7. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly drying described in (2) refers in 60~80 DEG C of dry 4~8h.

8. a kind of preparation method of amino acid@Cu-BTC compound adsorbents according to claim 1, it is characterised in that：Step Suddenly vacuum activating described in (3) refers to that 8~16h of vacuum activating is carried out at 120~150 DEG C.

9. a kind of amino acid@Cu-BTC compound adsorbents, it is characterised in that：Pass through claim 1~8 any one of them method It is prepared.