CN115385401B - A kind of porous three-dimensional network structure lanthanum iron nickel perovskite material and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of composite catalysis, and specifically relates to a porous three-dimensional network structure lanthanum iron nickel perovskite material and its preparation method and application. The porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the invention has high stability, good catalytic performance, stable toluene removal effect, high purity and low impurity content. The results of the examples show that the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention catalytically cracks toluene has good toluene removal rate and three-phase product controllability, the toluene conversion rate remains above 82.275%, and it is easy to recover and condense. The yield of components can reach 89.304% of the total mass of the product. The yield of solid products and gas products produced by catalytic cracking is small, and only a small amount of harmless non-condensable gas and solid carbon nanotubes are produced.

Description

A porous three-dimensional network structure lanthanum iron nickel perovskite material and its preparation method and application

Technical field

The invention belongs to the technical field of composite catalysis, and specifically relates to a porous three-dimensional network structure lanthanum iron nickel perovskite material and its preparation method and application.

Background technique

Toluene is a high-carbon aromatic hydrocarbon compound that is flammable and can form explosive mixtures with steam or air. It also has low toxicity and carcinogenic properties. It is widely present in pyrolysis oil and gas. It is often used as a tar model compound to evaluate catalysts. Performance of catalytic reforming of tar. In order to reduce the impact of toluene on the environment and equipment operation stability, toluene needs to be purified and treated.

Perovskite oxide has unique adjustable volume and various surface properties. It has been widely used in the fields of photocatalysis, electrocatalysis and catalytic oxidation, and has produced great results in the degradation of organic matter, the reforming of methane and carbon dioxide, and the efficient removal of VOCs. good effect. Perovskite oxide exhibits a regular octahedral structure, which can effectively limit atomic positions. Well-dispersed active metal particles can reduce the formation of larger metal clusters on the catalyst surface, effectively avoiding carbon deposition and sintering of active metal atoms; perovskite catalysts It has high thermal stability in a wide temperature range, which makes the catalyst have a longer service life and reduces the cost of use; the perovskite oxide has good lattice oxygen migration and conversion capabilities, which can effectively remove carbon on the surface of the material. This oxygen-deficient, non-stoichiometric ratio in perovskite oxides can then be used to regenerate oxygen or air from the environment.

Existing perovskite catalysts for catalytically reforming toluene mainly achieve catalytic oxidation or steam reforming of toluene by introducing oxygen or water vapor as a gasification agent to obtain high calorific value combustible gas. However, the components of pyrolysis oil and gas are complex, and the sulfur- and nitrogen-containing gas components will affect the catalytic stability of the existing catalytic reforming technology, and the toluene removal rate is unstable.

Contents of the invention

The object of the present invention is to provide a porous three-dimensional network structure lanthanum iron nickel perovskite material and its preparation method and application. The porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the invention has high stability and toluene removal effect. Stablize.

In order to achieve the above objects, the present invention provides the following technical solutions:

The invention provides a method for preparing a porous three-dimensional network structure lanthanum iron nickel perovskite material, which includes the following steps:

(1) Heat and mix soluble lanthanum salt, soluble nickel salt, soluble iron salt, dispersant and water to obtain a premix;

(2) Add the premixed liquid into a closed container and heat to perform a hydrothermal reaction to obtain a suspension;

(3) The suspension is sequentially subjected to solid-liquid separation and calcination to obtain a porous three-dimensional network structure lanthanum iron nickel perovskite material.

Preferably, the mass ratio of the soluble lanthanum salt and the soluble nickel salt is 2.14-21.4:1; the mass ratio of the soluble nickel salt and the soluble iron salt is 0.068-5.544:1.

Preferably, the ratio of the total molar amount of the dispersant to the soluble lanthanum salt, the soluble iron salt and the soluble nickel salt is 1 to 1.5:1; the total molar ratio of the water to the soluble lanthanum salt, the soluble iron salt and the soluble nickel salt is The quantity ratio is 20~60:1.

Preferably, the temperature of the hydrothermal reaction is 170-190°C, and the holding time is 9-10 hours.

Preferably, the calcination temperature is 700-1000°C, and the holding time is 2-6 hours.

Preferably, the soluble lanthanum salt is lanthanum nitrate hexahydrate; the soluble nickel salt is nickel acetate tetrahydrate; and the soluble iron salt is iron nitrate nonahydrate.

Preferably, the heating and mixing is performed under stirring conditions, and the stirring rate is 400 to 500 r/min. The heating and mixing includes a first stage and a second stage in sequence, and the temperature of the first stage is At room temperature, the time is 30 to 90 minutes, and the temperature of the second stage is 45 to 60°C, and the time is 30 to 60 minutes.

The present invention also provides a porous three-dimensional network structure lanthanum iron nickel perovskite material obtained by the preparation method described in the above solution. The surface of the porous three-dimensional network structure lanthanum iron nickel perovskite material contains oxygen species, and the oxygen species include Adsorbed oxygen and lattice oxygen, the adsorbed oxygen accounts for 58.5-58.7% of the total amount of oxygen species, and the lattice oxygen accounts for 37.6-37.8% of the total amount of oxygen species.

The present invention also provides the application of the porous three-dimensional network structure lanthanum iron nickel perovskite material described in the above solution in catalytic cracking of toluene.

Preferably, the concentration of toluene is ≤400g/Nm ³ and the temperature of catalytic cracking is ≥700°C.

The invention provides a method for preparing a porous three-dimensional network structure lanthanum iron nickel perovskite material. The present invention prepares porous three-dimensional network structure lanthanum iron nickel perovskite material through solvothermal method. Through the high dispersion and expansion characteristics of the hot solvent in the closed space, the dispersion of the metal active components during the preparation process is improved and the particles are avoided. The hard agglomeration phenomenon promotes the construction of porous three-dimensional network structure lanthanum iron nickel perovskite materials and improves the catalytic performance of catalytic materials; at the same time, the high concentration liquid phase reaction space improves the crystallization dispersion of the material and reduces the particle size of the catalytic material. Small and stable within the range of 100 to 200 nm, the solvent oxygen in the liquid phase can further participate in crystal construction and be converted into material lattice oxygen and surface adsorbed oxygen; in addition, the preparation method provided by the invention is safe and efficient, with simple steps and convenient operation.

The present invention also provides a porous three-dimensional network structure lanthanum iron nickel perovskite material obtained by the preparation method described in the above solution. The surface of the porous three-dimensional network structure lanthanum iron nickel perovskite material contains oxygen species, and the oxygen species include Adsorbed oxygen and lattice oxygen, the adsorbed oxygen accounts for 58.5-58.7% of the total amount of oxygen species, and the lattice oxygen accounts for 37.6-37.8% of the total amount of oxygen species. The porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the invention has a uniform, stable and regular controllable porous three-dimensional network perovskite structure. The crystal network is composed of uniform particles of 100 to 200 nm, and the surface of the material absorbs oxygen and crystallization. Rich in oxygen species, adsorbed oxygen accounts for 58.59% of the total oxygen species, and lattice oxygen accounts for 37.66% of the total oxygen species. These oxygen species can participate in the catalytic oxidation process of toluene and the removal of carbon on the surface of the material. The porous three-dimensional network The specific particle size of the structural lanthanum iron nickel perovskite material and the abundant surface adsorbed oxygen limit the gas production process during the catalytic reforming of toluene, and reduce the production of solid products, catalytically cracking toluene into small molecular organic matter, improving Catalytic reforming of toluene produces the proportion of easily recoverable condensable components to achieve control of the selectivity of three-phase products. The porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the invention has high stability, good catalytic performance, stable toluene removal effect, high purity and low impurity content.

The present invention also provides the application of the porous three-dimensional network structure lanthanum iron nickel perovskite material described in the above solution in catalytic cracking of toluene. The porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention shows good catalytic stability and catalytic activity when used to catalytically crack toluene. In a 24-hour continuous experiment at 700°C, the three-phase products and gases of catalytic cracking of toluene were There are no obvious fluctuations or changes in product selectivity. It can be seen that the porous three-dimensional network structure lanthanum iron nickel perovskite material of the present invention has obvious advantages in catalytic stability. Moreover, the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention has good toluene removal rate and three-phase product controllability for catalytic cracking of toluene. The toluene conversion rate remains above 82.275%, and the yield of condensable components is easy to recover. It can reach 89.304% of the total product mass. The yield of solid products and gas products produced by catalytic cracking is small, and only a small amount of harmless non-condensable gas and solid carbon nanotubes are produced. It is not polluting or harmful to the environment, and has good application and promotion prospect.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the drawings of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is the XRD pattern of the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention;

Figure 2 is an SEM pattern of the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention;

Figure 3 is the XPS oxygen species spectrum of the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention;

Figure 4 shows the 24h catalytic reforming toluene conversion rate and the total output of three-phase products of the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention;

Figure 5 shows the relative volume proportions (within 24 hours) of each component of the catalytic reforming of toluene oil and gas synthesis gas using the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention;

Figure 6 is an SEM pattern of the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention and the LaFe _0.5 Ni _0.5 O ₃ catalytic material prepared in Comparative Example 1.

Detailed ways

The invention provides a method for preparing a porous three-dimensional network structure lanthanum iron nickel perovskite material, which includes the following steps:

(1) Heat and mix soluble lanthanum salt, soluble nickel salt, soluble iron salt, dispersant and water to obtain a premix;

(2) Add the premixed liquid into a closed container and heat to perform a hydrothermal reaction to obtain a suspension;

(3) The suspension is sequentially subjected to solid-liquid separation and calcination to obtain a porous three-dimensional network structure lanthanum iron nickel perovskite material.

In the present invention, soluble lanthanum salt, soluble nickel salt, soluble iron salt, dispersant and water are heated and mixed to obtain a premixed liquid. In the present invention, the soluble lanthanum salt is preferably lanthanum nitrate hexahydrate; the soluble nickel salt is preferably nickel acetate tetrahydrate; the soluble iron salt is preferably ferric nitrate nonahydrate; the dispersant preferably includes lemon monohydrate One or both of acid and citric acid; the water is preferably distilled water; the mass ratio of the soluble lanthanum salt and the soluble nickel salt is preferably 2.14~21.4:1, more preferably 4.2~4.4:1; the The mass ratio of the soluble nickel salt and the soluble iron salt is preferably 0.068~5.544:1, more preferably 0.60~0.63:1; the ratio of the dispersant to the total molar amount of the soluble lanthanum salt, the soluble iron salt and the soluble nickel salt is preferably It is 1 to 1.5:1, more preferably 1.2 to 1.5:1, further preferably 1.5:1; the ratio of the total molar amount of water to the soluble lanthanum salt, soluble iron salt and soluble nickel salt is preferably 20 to 60: 1, more preferably 25 to 30:1. In specific embodiments of the present invention, the nickel acetate tetrahydrate used is a non-explosive drug and is low in cost. It is combined with a dispersant to strengthen the dispersion of the nickel salt in the aqueous phase to obtain high purity and Catalytic materials with uniform distribution of active components. In specific embodiments of the present invention, by limiting the dosage ratio of the dispersant, the present invention can enhance the dispersion of the metal salt precursor in water and reduce other steps to enhance the dispersion of the metal salt. At the same time, there is no need to add other components other than the dispersant. Other additives eliminate the need for pH adjustment, reduce the use of alkali, avoid the introduction of other elements, improve the safety of the preparation process and the purity of the porous three-dimensional network structure lanthanum iron nickel perovskite material. The porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention has a perovskite structure, and the limited nickel iron atomic ratio is conducive to the formation of a nickel iron alloy during the reaction process, so that the material exhibits high activity and strong stability. sex.

In the present invention, the heating and mixing method is preferably stirring; the stirring rate is preferably 400 to 500 r/min, and more preferably 420 to 460 r/min; the heating and mixing preferably includes the first stage and the following steps in sequence. The second stage; the temperature of the first stage is preferably room temperature, and the time is preferably 30 to 90 minutes, more preferably 45 to 70 minutes; the temperature of the second stage is preferably 45 to 60°C, and more preferably 50 to 55°C. , the time is preferably 30 to 60 minutes, more preferably 30 to 45 minutes. In the present invention, the premixed liquid is preferably cooled after the heating and mixing is completed; the final temperature of the cooling is preferably room temperature; and the cooling is preferably natural cooling. In specific embodiments of the present invention, continuous stirring using the above stirring rate helps to improve the dispersion of the metal salt in the aqueous phase, avoid aggregation of elements, and improve the dispersion of the elements of the generated material.

After obtaining the premixed liquid, the present invention adds the premixed liquid into a closed container and heats it for hydrothermal reaction to obtain a suspension. In the present invention, the temperature of the hydrothermal reaction is preferably 170-190°C, more preferably 180-185°C, and the holding time is preferably 9-10h, more preferably 9-9.5h.

After obtaining the suspension, the present invention sequentially performs solid-liquid separation and calcination on the suspension to obtain a porous three-dimensional network structure lanthanum iron nickel perovskite material. In the present invention, the separation method is preferably centrifugation; the number of times of centrifugation is preferably 3 to 4 times, more preferably 4 times, in order to quickly obtain uniform precipitated components; the rotation speed of the centrifugation is preferably 4000 to 4,000 to 4500r/min, more preferably 4200~4500r/min, the time is preferably 10~15min, more preferably 12~15min; after each centrifugation is completed, the obtained solid product is preferably washed; after the last centrifugation is completed, the obtained The washed solid product is dried to obtain dry matter; the washing reagents are preferably water and ethanol; the drying is preferably oven drying; the drying device is preferably a blast drying oven; the drying temperature is preferably The temperature is 100 to 105°C, more preferably 105°C, and the time is preferably 18 to 24 hours, more preferably 20 to 22 hours.

In the present invention, the calcination temperature is preferably 700 to 1000°C, more preferably 800 to 900°C, and the holding time is preferably 2 to 6 hours, more preferably 2 to 4 hours. In the present invention, the calcination preferably includes: programming the muffle furnace to the calcination temperature for calcination, followed by cooling and grinding after the calcination is completed; the final temperature of the cooling is preferably room temperature; the cooling method is preferably natural cooling. . Through calcination, the present invention contributes to the evacuation of gas in the channels of the porous three-dimensional network structure lanthanum iron nickel perovskite material and the formation of the composite metal oxide structure.

The present invention also provides a porous three-dimensional network structure lanthanum iron nickel perovskite material obtained by the preparation method described in the above solution. The surface of the porous three-dimensional network structure lanthanum iron nickel perovskite material contains oxygen species, and the oxygen species include 58.5~58.7% adsorbed oxygen and 37.6~37.8% lattice oxygen. In the present invention, the oxygen species includes 58.5% to 58.7% of adsorbed oxygen, preferably 58.59%; the oxygen species includes 37.6% to 37.8% of lattice oxygen, preferably 37.66%. In the present invention, the porous three-dimensional network structure lanthanum iron nickel perovskite material is preferably LaFe _0.5 Ni _0.5 O ₃ .

The present invention also provides the application of the porous three-dimensional network structure lanthanum iron nickel perovskite material described in the above solution in catalytic cracking of toluene.

In the present invention, the application preferably includes: adding porous three-dimensional network structure lanthanum iron nickel perovskite material into a vertical quartz tube, and then introducing carrier gas and toluene oil gas to perform a catalytic reforming reaction. In the present invention, the molar ratio of the porous three-dimensional network structure lanthanum iron nickel perovskite material and the toluene oil and gas input amount per hour is preferably 0.52 to 0.53:1, more preferably 0.524 to 0.526:1; the carrier The gas is preferably nitrogen; the flow rate of the carrier gas is preferably 100~300 SCCM, more preferably 150 SCCM; the flow rate of the toluene oil gas is preferably 3.5~3.7g/h, more preferably 3.6L/h; in the toluene oil gas The concentration of toluene is preferably ≤400g/Nm ³ , more preferably 50-400g/Nm ³ ; the toluene oil and gas are preferably continuously fed through a syringe pump with pipeline auxiliary heat, and the temperature of the feed is preferably 180-250°C , more preferably 190~210°C; the temperature of the catalytic reforming reaction is preferably ≥700°C, more preferably 700~900°C, further preferably 750~850°C; the temperature of the catalytic reforming reaction is preferably passed through a vertical The tube furnace is controlled to preferably keep the temperature of the catalyst layer in the vertical quartz tube constant at the temperature of the catalytic reforming reaction. In the present invention, post-treatment is preferably performed after the catalytic reforming reaction is completed; the post-treatment preferably includes: absorbing unreacted toluene through an absorption liquid; the absorption liquid preferably includes one or both of methanol and n-hexane. kind.

At the temperature of the catalytic reforming reaction limited by the present invention, the output of solid products and gas products produced by catalytic reforming is small, and the toluene conversion rate is high; when the temperature is too high, the proportion of gas products in catalytic cracking is likely to increase. When the temperature is too low, When, the toluene conversion rate will decrease.

In order to further illustrate the present invention, the solutions of the present invention are described in detail below with reference to the drawings and examples, but they should not be understood as limiting the protection scope of the present invention.

Example 1

The preparation method of porous three-dimensional network structure lanthanum iron nickel perovskite material, the preparation steps of preparing 50mmol LaFe _0.5 Ni _0.5 O ₃ catalytic material are as follows:

(1) Add 21.6505g of La(NO ₃ ) ₃ ·6H ₂ O, 10.1000g of Fe(NO ₃ ) ₃ ·9H ₂ O, and 6.2210g of Ni(CH ₃ COO) ₂ ·4H ₂ to 50 mL of distilled water. O and 30.0g citric acid monohydrate, and stir them at a constant speed of 430r/min for 30min to obtain a homogeneous precursor solution;

(2) Continue to heat the homogeneous precursor solution to 50°C and stir for 60 minutes, cool and transfer to a hydrothermal reaction kettle;

(3) Heat the hydrothermal reaction kettle to 180°C and conduct a temperature-controlled reaction for 9.5 hours to obtain a suspension;

(4) Transfer the suspension to a centrifuge tube, centrifuge at 4000r/min for 10 minutes, centrifuge three times continuously and wash with water and ethanol to obtain precipitated material;

(5) Transfer the precipitated material to a 105°C blast drying oven and dry it for 24 hours to constant weight to obtain dry material;

(6) Place the dry matter in a muffle furnace, raise the temperature to 800°C at a heating rate of 1°C/min, and calcine at a constant temperature for 2 hours. After cooling, take it out and grind it to less than 10 mesh to obtain porous LaFe _0.5 Ni _0.5 O without impurities. ₃ Catalytic materials.

Example 2

Preparation method of porous three-dimensional network structure lanthanum iron nickel perovskite material, the steps for preparing 40 mmol of LaFe _0.5 Ni _0.5 O ₃ catalytic material are as follows:

(1) Add 17.32g of La(NO ₃ ) ₃ ·6H ₂ O, 8.08g of Fe(NO ₃ ) ₃ ·9H ₂ O, and 4.9768g of Ni(CH ₃ COO) ₂ ·4H ₂ in sequence to 40 mL of distilled water. O and 25.2g of citric acid monohydrate, and stir them at a constant speed of 430r/min for 30min to obtain a homogeneous precursor solution;

(2) Continue to heat the homogeneous precursor solution to 50°C and stir for 60 minutes, cool and transfer to a hydrothermal reaction kettle;

(3) Heat the hydrothermal reaction kettle to 180°C and conduct a temperature-controlled reaction for 9.5 hours to obtain a suspension;

(4) Transfer the suspension to a centrifuge tube, centrifuge at 4000r/min for 10 minutes, centrifuge three times continuously and wash with water and ethanol to obtain precipitated material;

(5) Transfer the precipitated material to a 105°C blast drying oven and dry it for 24 hours to constant weight to obtain dry material;

(6) Place the dry matter in a muffle furnace, raise the temperature to 800°C at a heating rate of 1°C/min, and calcine at a constant temperature for 2 hours. After cooling, take it out and grind it to less than 10 mesh to obtain porous LaFe _0.5 Ni _0.5 O without impurities. ₃ Catalytic materials.

Example 3

Preparation method of porous three-dimensional network structure lanthanum iron nickel perovskite material, the steps for preparing 80 mmol of LaFe _0.5 Ni _0.5 O ₃ catalytic material are as follows:

(1) Add 34.64g of La(NO ₃ ) ₃ ·6H ₂ O, 16.16g of Fe(NO ₃ ) ₃ ·9H ₂ O, and 9.9536g of Ni(CH ₃ COO) ₂ ·4H ₂ to 80 mL of distilled water. O and 50.4g of citric acid monohydrate, and stir them at a constant speed of 450r/min for 60min to obtain a homogeneous precursor solution;

(2) Continue to heat the homogeneous precursor solution to 55°C and stir for 60 minutes, cool and transfer to a hydrothermal reaction kettle;

(3) Heat the hydrothermal reaction kettle to 190°C, conduct a temperature-controlled reaction for 10 hours, and obtain a suspension;

(4) Transfer the suspension to a centrifuge tube, centrifuge at 4000r/min for 10 minutes, centrifuge three times continuously and wash with water and ethanol to obtain precipitated material;

(5) Transfer the precipitated material to a 105°C blast drying oven and dry it for 24 hours to constant weight to obtain dry material;

(6) Place the dry matter in a muffle furnace, raise the temperature to 800°C at a heating rate of 1°C/min, and calcine at a constant temperature for 2 hours. After cooling, take it out and grind it to less than 10 mesh to obtain porous LaFe _0.5 Ni _0.5 O without impurities. ₃ Catalytic materials.

Comparative example 1

LaFe _0.5 Ni _0.5 O ₃ is prepared by the sol-gel method. The preparation steps are as follows:

(1) Add 21.6505g of La(NO ₃ ) ₃ ·6H ₂ O, 10.1000g of Fe(NO ₃ ) ₃ ·9H ₂ O, and 6.2210g of Ni(CH ₃ COO) ₂ ·4H ₂ to 50 mL of distilled water. O, 25.2170g citric acid monohydrate and 2.976g ethylene glycol, and stir them at a constant speed of 430r/min for 30min to obtain a homogeneous precursor solution;

(2) Heat the homogeneous precursor solution to 80°C and stir at a constant temperature of 430r/min for 1.5h to obtain a viscous wet gel;

(3) Transfer the viscous wet gel to a 105°C blast drying oven and dry it for 24 hours to constant weight to obtain a dry gel;

(4) Grind the xerogel and pass it through a 10-mesh screen to obtain xerogel powder. Place the xerogel powder in a muffle furnace and heat it to 700°C at a heating rate of 5°C/min. After calcining for 4 hours, cool to 500°C, continue to hold the temperature for 2 hours, and cool to normal temperature to obtain impurity-free LaFe _0.5 Ni _0.5 O ₃ catalytic material.

Example 4

The application of porous three-dimensional network structure lanthanum iron nickel perovskite material to catalytically crack toluene to produce easily recoverable condensable components. The specific steps are as follows:

(1) Place 5g of the LaFe _0.5 Ni _0.5 O ₃ catalytic material obtained in Example 1 in a vertical quartz tube (60mm×1000mm);

(2) Nitrogen is used as the carrier gas of toluene oil and gas, the nitrogen flow rate is 150SCCM, toluene oil and gas are continuously fed through a syringe pump with pipeline auxiliary heat, and the toluene oil and gas concentration is controlled to 400g/Nm ³ ;

(3) During the catalytic reforming process, a vertical tube furnace is used for heating to keep the temperature of the catalyst layer constant at 700°C;

(4) Absorb unreacted toluene through the absorption liquid, continuously feed it for 24 hours at a temperature of 700°C, and conduct component analysis and gas production statistics on the generated combustible gas through a gas analyzer;

The LaFe _0.5 Ni _0.5 O ₃ catalytic material prepared in Example 1 was also subjected to the above test.

The results are shown in Table 1.

Table 1 Example 4 and Comparative Example 1 continuous 24h experimental product distribution

According to Table 1, it can be seen that the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention has good stability in catalytically cracking toluene. At this temperature, the toluene conversion rate can reach more than 82.28%, while ensuring a high toluene removal rate. On the basis of this, the yield of easily recoverable condensable components was simultaneously achieved, and the product proportion increased by 52.79%, proving that the reaction process has high selectivity for condensable components, the gas production efficiency remains stable, and the catalytic performance remains unchanged. Obvious fluctuations are generated, and the catalytic material achieves the design expectations; moreover, the gas production of the catalytic cracking of toluene by the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention is significantly lower than that of the sol-gel method, which limits the catalytic reforming of toluene. The gas production process in the invention realizes the control of the selectivity of three-phase products; the porous three-dimensional network structure lanthanum iron nickel perovskite material provided in Example 1 of the present invention has high purity, good catalytic performance, and certain promotion The advantage is that the catalytic material preparation method can be selected according to specific product requirements.

The porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention was subjected to X-ray diffraction analysis, and the results are shown in Figure 1. According to Figure 1, it can be seen that the present invention successfully prepares a porous three-dimensional network structure lanthanum iron nickel perovskite material.

SEM analysis was performed on the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention, and the results are shown in Figure 2. According to Figure 2, it can be seen that the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention has a uniform, stable, regular and controllable porous three-dimensional network perovskite structure, and the crystal network is composed of uniform particles of 100 to 200 nm.

The XPS test was performed on the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention, and the results are shown in Figure 3. According to Figure 3, it can be seen that the surface of the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention is rich in adsorbed oxygen and crystallized oxygen species. The adsorbed oxygen accounts for 58.59% of the total oxygen species, and the lattice oxygen accounts for 58.59% of the total oxygen species. 37.66%.

The 24-hour catalytic reforming toluene conversion rate and the total output of three-phase products of the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention were detected. The detection method was: measuring the solid product output by the weight difference method before and after the reaction; The output of non-condensable gas components is obtained through the analysis, detection and measurement of the automated gas analyzer; the output of the condensable components is obtained through the mass difference method and the absorption liquid quantitative determination method. The results are shown in Figure 4. According to Figure 4, it can be seen that the porous three-dimensional network structure lanthanum iron nickel perovskite material of the present invention catalytically reforms toluene in 24 hours, the toluene conversion rate remains above 82.275%, and the yield of easily recovered condensable components is above 85% of the total product mass. , the yield of solid products and gas products produced by catalytic cracking is small, and only a small amount of harmless non-condensable gases such as CO ₂ and H ₂ and solid carbon nanotubes are produced. It can be seen that the porous three-dimensional network structure lanthanum iron nickel perovskite material of the present invention has It has obvious advantages in catalytic stability, good toluene removal rate and three-phase product control.

The components of the catalytic reforming of toluene oil and gas synthesis gas prepared by the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention were analyzed, and the results are shown in Figure 5. According to Figure 5, it can be seen that the catalytic material prepared by the present invention has good catalytic stability. In the 24-hour continuous experiment, the catalytic material products did not fluctuate significantly, and all existed in the form of harmless non-condensable gases such as CO ₂ and H _2. According to the later To expand the specific processing scale, high-value recycling of syngas can be considered.

The high-purity porous LaFe _0.5 Ni _0.5 O ₃ catalytic material of Example 1 and the high-purity LaFe _0.5 Ni _0.5 O ₃ catalytic material prepared in Comparative Example 1 were observed using a scanning electron microscope. The results are shown in Figure 6. According to Figure 6, it can be seen that there are obvious differences in the microscopic particle size and morphology structure between the porous three-dimensional network structure lanthanum iron nickel perovskite material prepared in Example 1 of the present invention and the LaFe _0.5 Ni _0.5 O ₃ catalytic material prepared in Comparative Example 1. The difference is that the particle size of the porous three-dimensional network-structured lanthanum-iron-nickel perovskite material prepared by the present invention is maintained at 100-200 nm, and it has a multi-layer porous three-dimensional network structure, which improves the selectivity of the final three-phase product. The particle size of the LaFe _0.5 Ni _0.5 O ₃ catalytic material prepared by the sol-gel method in Comparative Example 1 is smaller, which will increase the production of gas products.

It can be seen from the above examples that the porous three-dimensional network structure lanthanum iron nickel perovskite material provided by the present invention has high stability, good catalytic performance, stable toluene removal effect, high purity, low impurity content, and limits the gas production of catalytic reforming of toluene. process, reducing the production of solid products, catalytically cracking toluene into small molecular organic matter, increasing the proportion of easily recoverable condensable components in the catalytic reforming of toluene, achieving the control of three-phase product selectivity, and showing good catalytic Stability and catalytic activity, it has good toluene removal rate and three-phase product control, easy recovery of condensable components and high yield, small yield of solid products and gas products, and only produces a small amount of harmless non-condensable gas and solid carbon nanotubes.

Although the above embodiments describe the present invention in detail, they are only part of the embodiments of the present invention, not all embodiments. Other embodiments can also be obtained according to this embodiment without any inventive step, and these embodiments are all It belongs to the protection scope of the present invention.

Claims (8)

1. A method for preparing a porous three-dimensional network structure lanthanum iron nickel perovskite material, including the following steps: (1) Heat and mix soluble lanthanum salt, soluble nickel salt, soluble iron salt, dispersant and water to obtain a premix; (2) Add the premixed liquid into a closed container and heat to perform a hydrothermal reaction to obtain a suspension; (3) The suspension is sequentially subjected to solid-liquid separation and calcination to obtain a porous three-dimensional network structure lanthanum iron nickel perovskite material; The ratio of the total molar amount of the dispersant to the soluble lanthanum salt, the soluble iron salt and the soluble nickel salt is 1 to 1.5:1; The soluble lanthanum salt is lanthanum nitrate hexahydrate; the soluble nickel salt is nickel acetate tetrahydrate; the soluble iron salt is iron nitrate nonahydrate; The heating mixing is performed under stirring conditions, and the stirring rate is 400~500 r/min. The heating mixing includes a first stage and a second stage performed in sequence, and the temperature of the first stage is room temperature. The time is 30~90 min, the temperature of the second stage is 45~60°C, and the time is 30~60 min; The dispersant is one or both of citric acid monohydrate and citric acid. 2. The preparation method according to claim 1, characterized in that the mass ratio of the soluble lanthanum salt and the soluble nickel salt is 2.14~21.4:1; the mass ratio of the soluble nickel salt and the soluble iron salt is 0.068~ 5.544:1. 3. The preparation method according to claim 1, characterized in that the ratio of the total molar amount of water to soluble lanthanum salt, soluble iron salt and soluble nickel salt is 20 to 60:1. 4. The preparation method according to claim 1, characterized in that the temperature of the hydrothermal reaction is 170~190°C, and the holding time is 9~10 h. 5. The preparation method according to claim 1, characterized in that the calcination temperature is 700~1000°C, and the holding time is 2~6 h. 6. The porous three-dimensional network structure lanthanum iron nickel perovskite material obtained by the preparation method of any one of claims 1 to 5, the surface of the porous three-dimensional network structure lanthanum iron nickel perovskite material contains oxygen species, so The oxygen species include adsorbed oxygen and lattice oxygen, the adsorbed oxygen accounts for 58.5~58.7% of the total oxygen species, and the lattice oxygen accounts for 37.6~37.8% of the total oxygen species. 7. Application of the porous three-dimensional network structure lanthanum iron nickel perovskite material described in claim 6 in catalytic cracking of toluene. 8. The application according to claim 7, characterized in that the concentration of toluene is ≤400 g/Nm ³ and the temperature of the catalytic cracking is ≥700°C.