Nickel-silicon catalyst for dry reforming of methane and method for preparing the same

Abstract

The application relates to a nickel-silicon catalyst suitable for methane dry reforming and a preparation method thereof, and belongs to the field of methane dry reforming. The catalyst takes special silica with a microstructure as a carrier, nickel is loaded to the silica material with a double mesoporous model (BMMs), the nickel-silicon catalyst with good nickel dispersity is obtained by calcination in air, and the catalyst has high initial activity and high stability in the methane dry reforming reaction, especially in the medium and low temperature reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation and application, and particularly relates to a nickel silicon catalyst suitable for medium and low temperature methane dry reforming and a preparation method thereof. Background Art

[0002] Dry reforming of methane (DRM) is a process that converts methane and carbon dioxide into high-value-added chemicals. This reaction has high economic and environmental potential because it can convert two inexpensive and abundant carbon sources into higher-value-added chemicals. However, in practice, research on dry reforming of methane faces many challenges, such as high energy consumption and high investment due to high-temperature reactions, as well as problems such as high-temperature sintering and carbon deposition of catalysts. Therefore, the development of catalysts suitable for medium- and low-temperature dry reforming of methane and carbon dioxide has gradually attracted attention.

[0003] The catalysts for the medium- and low-temperature reforming of methane to carbon dioxide mainly include two categories: precious metals (Ru, Rh, Pd, Pt) and non-precious metals (Ni, Co, Cu, Fe). Among them, precious metal catalysts have the advantages of high catalytic activity, strong resistance to carbon deposition, good stability, etc., but precious metal resources are limited and expensive, which restricts their large-scale application in industry. Among non-precious metals, the activity of metallic Ni is comparable to that of precious metals, and it is recognized as the catalyst with the most promising industrial application. Silicon dioxide is often used as a substrate for dispersing nickel due to its excellent thermal stability and high specific surface area, while most nickel-silicon catalysts with good catalytic performance are prepared through complex and expensive routes, such as preparing encapsulated structures or core-shell structures with silicon precursors. Currently, the common methods for extending the life and activity of catalysts in methane dry reforming are to limit the size of nickel, improve the dispersion of nickel, and enhance the interaction between nickel and the substrate. The silica supports currently used in research mostly use microporous or mesoporous materials with a single pore size and high crystallinity as catalyst supports, such as MCM-41 / SBA-15, FDU-2, MCM-50, KIT-5, etc. (Journal of Industrial and Engineering Chemistry 107 (2022) 20-30, International Journal of Hydrogen Energy 47 (2022) 41596-41620, Fuel Processing Technology 169 (2018) 199-206). However, single mesoporous silica materials usually have a high specific surface area, which is conducive to the dispersion of active components. However, in order to obtain a larger specific surface area, smaller pores will limit the diffusion of reactants or products, easily produce carbon deposits, and hinder the commercial application of silica-based catalysts. The preparation of bi-porous silica materials is shown in patents CN104261414A, CN105366682A, CN103663473A, CN102059118A and CN111348656A. CN104261414A mainly uses H3PO4 as a silicon source hydrolysis catalyst, and the synthesized silica has a pore size of 2.1-2.6nm and 3.3-3.9nm bi-mesoporous silica molecular sieve. The bi-mesoporous silica microspheres prepared by CN105366682A have a specific surface area of ​​300-600m 2 The dual-mesoporous silica material prepared in CN103663473A has a grape-like morphology, with two ordered pore sizes of 1.5 to 4.2 nm and 4.2 to 15 nm, respectively. Although these dual-mesoporous silica materials also have dual pore characteristics, there are few reports in the literature or patents on the use of dual-mesoporous silica as a catalyst support for medium- and low-temperature methane-carbon dioxide reforming reactions. Summary of the Invention

[0004] In order to overcome the problems of easy carbon deposition and sintering and poor initial activity at low temperatures in current silicon-nickel-based catalysts during application, the present invention aims to provide a nickel-silicon catalyst suitable for methane dry reforming and a preparation method thereof. The catalyst uses double-mesoporous silica as a carrier, and is obtained by loading metallic nickel onto a silica material of a double-mesoporous model (BMMs), and calcining in air to obtain a nickel-silicon catalyst with good nickel dispersion. The catalyst exhibits initial high activity and high stability in medium and low temperature methane dry reforming reactions. In particular, when a lower loading amount is used, it has initial high activity and high stability in medium and low temperature methane dry reforming.

[0005] A dual-mesoporous nickel-silicon catalyst suitable for medium- and low-temperature methane dry reforming is described. The catalyst comprises metallic nickel at a loading of 1% to 20%, preferably about 2%, and dual-mesoporous silica at a loading of 80% to 99%. The dual-mesoporous catalyst comprises worm-like pores with a first pore diameter of about 3 nm and spherical stacked pores with a second pore diameter of about 10 to 30 nm. The dual-mesoporous silica catalyst prepared by the present invention has a rich mesoporous structure and a specific surface area of ​​1200 to 1500 m 2 / g, with a high specific surface area (>700m 2 / g), tunable mesopore diameter, can be prepared under mild conditions, and is easy to synthesize and modify. It has good initial activity and stability in medium and low temperature methane dry reforming reactions and is expected to be prepared and applied on a large scale in industrial production.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a nickel-silicon catalyst suitable for methane dry reforming comprises the following steps:

[0008] (1) Preparation of dual mesoporous silica: The template is dissolved in deionized water to obtain a first solution at room temperature (20-60°C), and then a silicon source is slowly added dropwise, followed by a hydrolysis catalyst ammonia water, and stirred continuously until the solution becomes a white gel, which is then allowed to settle. The solution is then filtered, washed with deionized water, and dried in a drying oven (105-120°C) to obtain the desired dual mesoporous silica support.

[0009] The template agent can be one of hexadecyltrimethylammonium bromide, tetraethylammonium hydroxide, triethylamine, and triethanolamine, and the silicon source can be one of ethyl orthosilicate and methyl orthosilicate;

[0010] More preferably, 32 ml of tetraethyl orthosilicate corresponds to 460 ml of deionized water per 10.44 g of cetyltrimethylammonium bromide (CTAB).

[0011] (2) Silica-supported nickel salt: The nickel active component is loaded onto the silica carrier by an impregnation method, and the silica and nickel salt obtained in step (1) are dispersed in deionized water using water as a dispersant, and are fully stirred for 0.3 to 1.5 hours, and left at room temperature for 0.5 to 1 hour; then, the mixture is heated and mixed at 20 to 60° C. in a water bath for 1 to 4 hours, and the temperature is increased to 40 to 100° C., heated and mixed for 0.5 to 1 hour, and the obtained solid powder is dried to obtain the desired nickel-silicon catalyst precursor;

[0012] Alternatively, the nickel active component is loaded onto the silica carrier using a one-pot method, wherein the nickel salt and the template mentioned in step (1) are dissolved in deionized water, and then a silicon source and ammonia water are added for hydrolysis, and then filtered, washed with deionized water, and dried to form a nickel-silicon catalyst precursor.

[0013] (3) calcining the nickel silicon catalyst precursor obtained in step (2) at 500-750° C. in an air atmosphere for 1-4 h at a heating rate of 2-20° C. / min.

[0014] The nickel salt is selected from one or more of nickel nitrate hexahydrate, nickel sulfate, nickel chloride, nickel sulfamate, nickel bromide, and nickelous hydroxide.

[0015] The silica-supported nickel-based catalyst is used for medium- and low-temperature methane dry reforming, catalyzing the reaction of methane and carbon dioxide to produce synthesis gas (preferably H2 / CO≤1 in the synthesis gas, the closer to 1 the better).

[0016] The silica-supported nickel-based catalyst catalyzes methane dry reforming to produce synthesis gas at 400-900°C. Before the methane dry reforming, the catalyst is reduced with hydrogen at a reduction temperature of 350-750°C, held for 1-3 hours, and a heating rate of 2-20°C / min. The catalyst is then switched to an inert gas, such as nitrogen and argon, and purged for 30 minutes to remove hydrogen from the system. The molar ratio of methane to carbon dioxide in the feed gas for the methane dry reforming is 1:1-3:1, nitrogen is used as a balance gas, and the space velocity (GHSV) is 18,000-60,000 mL / h. -1 gcat -1 .

[0017] The preferred catalytic temperature is 600° C., and the catalytic reaction can be sustained and stably carried out for 10 to 100 hours.

[0018] Beneficial effects of the present invention:

[0019] In the prior art, it is difficult to achieve an initial methane conversion rate of over 40% at low to medium temperatures. However, the present invention achieves a methane conversion rate of over 44% and a carbon dioxide conversion rate of 54.19% at a relatively low loading of 2%. The catalyst of the present invention exhibits good initial catalytic activity and stability during the dry reforming of methane at medium to low temperatures. It exhibits high activity and good stability during the catalytic dry reforming of methane. Taking 2% Ni / BMMs as an example, at 600°C, the feed gas is 45ml CH4; 45ml CO2; 10ml N2, and the space velocity (GHSV) is 18,000 to 60,000mLh -1 gcat -1 Under the conditions of , the stability within 10h was tested by online gas chromatography. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a performance data diagram of different loading amounts of Ni / BMMs by the impregnation method (methane conversion rate: 1wt% corresponds to Example 1, 2wt% corresponds to Example 2, 5wt% corresponds to Example 3, and 10wt% corresponds to Example 4).

[0021] Figure 2 This is a performance data diagram of different loading amounts of Ni / BMMs using the impregnation method (carbon dioxide conversion rate: 1 wt% corresponds to Example 1, 2 wt% corresponds to Example 2, 5 wt% corresponds to Example 3, and 10 wt% corresponds to Example 4).

[0022] Figure 3 This is a performance data diagram of different loading amounts of Ni / BMMs by the impregnation method (H2 / CO ratio: 1wt% corresponds to Example 1, 2wt% corresponds to Example 2, 5wt% corresponds to Example 3, and 10wt% corresponds to Example 4).

[0023] Figure 4 Performance data of Ni / SBA15 impregnated by comparative example 1 (methane conversion)

[0024] Figure 5 Performance data of Ni / SBA15 impregnated by comparative example 1 (carbon dioxide conversion rate)

[0025] Figure 6 Performance data of Ni / SBA15 impregnated by comparative example 1 (H2 / CO ratio)

[0026] Figure 7 Performance data diagram of Ni / MSN impregnation method in comparative example 2 (methane conversion rate)

[0027] Figure 8 Performance data diagram of Ni / MSN impregnation method in comparative example 2 (carbon dioxide conversion rate)

[0028] Figure 9 Performance data diagram of Ni / MSN impregnation method of comparative example 2 (H2 / CO ratio)

[0029] Figure 10 Performance data of one-pot Ni / BMMs in Example 5 (a: CH4 conversion rate, b: CO2 conversion rate, c: H2 / CO)

[0030] Figure 11 The performance corresponding to the gradient heating of Ni / BMMs prepared by the immersion method in Example 2.

[0031] Figure 12 This is the SEM electron microscope image of Ni / BMMs prepared by the impregnation method. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the examples, but the present invention is not limited to the following examples.

[0033] 1. BMMs: Weigh 10.44 g of cetyltrimethylammonium bromide (CTAB) and dissolve it in 460 ml of deionized water. Stir until the CTAB is completely dissolved. Slowly add tetraethyl orthosilicate (32 ml) dropwise, then quickly add NH3·H2O (9.6 ml) until a white gel is formed and wash.

[0034] 2.SBA-15 synthesis

[0035] ① At 35°C, add 4.16g of P123 to 125ml of 2mol / L hydrochloric acid and 31ml of H2O and continue stirring for 10h to form a transparent solution.

[0036] ② Add 9.5 ml of TEOS dropwise into the mixed solution and continue stirring for 24 hours. Transfer the mixed solution to a stainless steel hydrothermal autoclave lined with polytetrafluoroethylene and crystallize at 100°C for 24 hours.

[0037] ③ After cooling to room temperature, filter, then wash with deionized water until neutral, and dry at 80℃ for 5 hours.

[0038] ④ Slowly heat the mixture to 550°C in a muffle furnace at a heating rate of 1°C / min for 6 hours to remove the template to obtain SBA-15.

[0039] 3.MSN Synthesis

[0040] Measure 480 ml of deionized water and place it in a large beaker. Weigh 1.002 g of CTAB and slowly add the CTAB to the beaker, mix, and stir until the CTAB is completely dissolved (80°C water bath). Then slowly add 3.0 ml (2 mol / L) NaOH solution (3 min), followed by 5.0 ml TEOS (2 min), stir for 2 h, filter the gel using a Buchner funnel, and repeatedly wash with deionized water until neutral. Finally, the white gel is dried in a conventional oven at 80°C for 12 h to obtain a t-MSN sample. Subsequently, the MSN is obtained by heating to 550°C at a rate of 1°C / min in a muffle furnace and maintaining this temperature for 6 h in air.

[0041] Example 1 (loading amount 1%)

[0042] The present invention provides a method for preparing a nickel-silicon catalyst suitable for methane dry reforming, comprising the following steps:

[0043] 1. Preparation of catalyst:

[0044] Silica-supported nickel salt: Weigh 0.04955 g of nickel nitrate hexahydrate and dissolve it in 15 ml of water. Then add 1 g of BMMs and stir thoroughly for 1 hour. Then, let it sit at room temperature for 1 hour. Heat and mix at 60°C in a water bath for 4 hours. Increase the temperature to 70°C and heat and mix for 1 hour. The resulting solid powder was dried overnight in a laboratory oven at 120°C to obtain the silica-supported nickel salt.

[0045] The silica-supported nickel salt obtained after drying was fully ground, and the ground powder was calcined at 700° C. (heating rate of 5° C. / min) for 4 hours in an air atmosphere to obtain a precursor of the catalyst Ni / BMMs.

[0046] 2. Experimental test of the stability of methane dry reforming reaction using Ni / BMMs

[0047] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate was 60 ml / min, the reduction temperature was from room temperature to 550°C, and it was held at 550°C for 2 hours, and the heating rate was 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1), the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion was 29.40%, the carbon dioxide conversion was 42.00%, and the H2 / CO ratio was 0.74. ( Figure 1-Figure 3 CH4 conversion rate, CO2 conversion rate, H2 / CO).

[0048] Example 2 (loading amount 2%)

[0049] 1. Preparation of catalyst:

[0050] Silica-supported nickel salt: Weigh 0.0991 g of nickel nitrate hexahydrate and dissolve it in 15 ml of water. Then add 1 g of BMMs and stir thoroughly for 1 hour. Then, let it sit at room temperature for 1 hour. Heat and mix at 60°C in a water bath for 4 hours. Increase the temperature to 70°C and heat and mix for 1 hour. The resulting solid powder was dried in a laboratory oven at 120°C overnight to obtain the silica-supported nickel salt.

[0051] The silica-supported nickel salt obtained after drying was fully ground, and the ground powder was calcined at 700° C. (heating rate of 5° C. / min) for 4 hours in an air atmosphere to obtain a precursor of the catalyst Ni / BMMs.

[0052] 2. Performance test of methane dry reforming reaction catalyzed by the Ni / BMMs synthesized above:

[0053] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate of 60 ml / min, reduction temperature from room temperature to 550°C, and dwelled at 550°C for 2 hours, with a heating rate of 10°C / min). Subsequently, the temperature was lowered to room temperature and nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1 ) and record the catalyst reaction activity; using 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ gradient temperature test, the experimental results are Figure 11 (CH4 conversion rate, CO2 conversion rate, H2 / CO); After the above-mentioned gradient temperature increase experiment, considering that the conversion rate of the product of methane dry reforming reaction increases with the increase of temperature, but considering that high temperature will bring higher energy costs in industry, it is preferred to conduct catalyst stability test at 600°C.

[0054] 3. Experimental test of the stability of methane dry reforming reaction using Ni / BMMs

[0055] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate was 60 ml / min, the reduction temperature was from room temperature to 550°C, and it was held at 550°C for 2 hours, and the heating rate was 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1 ), the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion was 44.00%, the carbon dioxide conversion was 54.19%, and the H2 / CO ratio was 0.86. ( Figure 1-Figure 3 CH4 conversion rate, CO2 conversion rate (H2 / CO).

[0056] Example 3 (loading amount 5%)

[0057] 1. Preparation of catalyst:

[0058] Silica-supported nickel salt: Weigh 0.2477g of nickel nitrate hexahydrate and dissolve it in 15ml of water. Then add 1g of BMMs and stir thoroughly for 1 hour. Then, let it sit at room temperature for 1 hour. Heat and mix at 60°C in a water bath for 4 hours. Increase the temperature to 70°C and heat and mix for 1 hour. The resulting solid powder was dried overnight in a laboratory oven at 120°C to obtain the silica-supported nickel salt.

[0059] The silica-supported nickel salt obtained after drying was fully ground, and the ground powder was calcined at 700° C. (heating rate of 5° C. / min) for 4 hours in an air atmosphere to obtain a precursor of the catalyst Ni / BMMs.

[0060] 2. Experimental test of the stability of methane dry reforming reaction using Ni / BMMs

[0061] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate was 60 ml / min, the reduction temperature was from room temperature to 550°C, and it was held at 550°C for 2 hours, and the heating rate was 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1), the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion rate was 35.21%, the carbon dioxide conversion rate was 46.86%, and the H2 / CO ratio was 0.79. ( Figure 1-Figure 3 CH4 conversion rate, CO2 conversion rate (H2 / CO).

[0062] Example 4 (loading amount 10%)

[0063] 1. Preparation of catalyst:

[0064] Silica-supported nickel salt: Weigh 0.4955 g of nickel nitrate hexahydrate and dissolve it in 15 ml of water. Then add 1 g of BMMs and stir thoroughly for 1 hour. Then, let it sit at room temperature for 1 hour. Heat and mix at 60°C in a water bath for 4 hours. Increase the temperature to 70°C and heat and mix for 1 hour. The resulting solid powder was dried overnight in a laboratory oven at 120°C to obtain the silica-supported nickel salt.

[0065] The silica-supported nickel salt obtained after drying was fully ground, and the ground powder was calcined at 700° C. (heating rate of 5° C. / min) for 4 hours in an air atmosphere to obtain a precursor of the catalyst Ni / BMMs.

[0066] 2. Experimental test of the stability of methane dry reforming reaction using Ni / BMMs

[0067] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate was 60 ml / min, the reduction temperature was from room temperature to 550°C, and it was held at 550°C for 2 hours, and the heating rate was 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1 ), the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion was 39.00%, the carbon dioxide conversion was 54.20%, and the H2 / CO ratio was 0.84. ( Figure 1-Figure 3 CH4 conversion rate, CO2 conversion rate (H2 / CO).

[0068] Comparative Example 1 (loading amount 2%)

[0069] 1. Preparation of catalyst:

[0070] Silica-supported nickel salt: Weigh 0.2477g of nickel nitrate hexahydrate and dissolve it in 15ml of water. Then add 1g of calcined SBA-15 and stir thoroughly for 1 hour. Allow to stand at room temperature for 1 hour. Heat and mix at 60°C in a water bath for 4 hours, then increase the temperature to 70°C and heat and mix for 1 hour. The resulting solid powder was dried in a laboratory oven at 120°C overnight to obtain silica-supported nickel salt.

[0071] The silica-supported nickel salt obtained after drying was fully ground, and the ground powder was calcined at 700° C. (heating rate of 5° C. / min) for 4 hours in an air atmosphere to obtain a precursor of the catalyst Ni / SBA-15.

[0072] 2. Experimental test on the stability of methane dry reforming reaction using Ni / SBA-15 catalyst:

[0073] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate was 60 ml / min, the reduction temperature was from room temperature to 550°C, and it was held at 550°C for 2 hours, and the heating rate was 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1 ), the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion was 34.09%, the carbon dioxide conversion was 46.90%, and the H2 / CO ratio was 0.760. ( Figure 4-Figure 6 CH4 conversion rate, CO2 conversion rate (H2 / CO).

[0074] Comparative Example 2 (loading amount 2%)

[0075] 1. Preparation of catalyst:

[0076] Silica-supported nickel salt: Weigh 0.2477g of nickel nitrate hexahydrate and dissolve it in 15ml of water. Then add 1g of MSN and stir thoroughly for 1 hour. The mixture is then allowed to stand at room temperature for 1 hour. Heat and mix at 60°C in a water bath for 4 hours, then increase the temperature to 70°C and heat and mix for 1 hour. The resulting solid powder is dried in a laboratory oven at 120°C overnight to obtain silica-supported nickel salt.

[0077] 2. Experimental test of the stability of methane dry reforming reaction using Ni / MSN catalyst

[0078] During the test, the catalyst dosage was 100 mg, the particle size was 40-60 mesh, and before methane dry reforming, it was reduced with 5% H2 / 90% Ar (total flow rate was 60 ml / min, the reduction temperature was from room temperature to 550°C, and it was held at 550°C for 2 hours, and the heating rate was 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to replace the hydrogen in the system. After the replacement was completed, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mLh -1 gcat -1 ), the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion rate was 29.93%, the carbon dioxide conversion rate was 42.31%, and the H2 / CO ratio was 0.679. ( Figure 7-Figure 9 CH4 conversion rate, CO2 conversion rate (H2 / CO).

[0079] Example 5 (loading amount 2%)

[0080] 1. One-pot preparation of catalyst:

[0081] Ni / BMMs were prepared using a one-pot method: 10.45 g of cetyltrimethylammonium bromide (CTAB), 416 mL of deionized water, and a predetermined amount of nickel nitrate solution (Si:Ni 1:0.02) were mixed in a large beaker and stirred until the CTAB was completely dissolved. 32 mL of tetraethyl orthosilicate (TEOS) was added dropwise, followed by the rapid addition of 9.6 mL of NH₃·H₂O with continuous stirring until the solution became a gel that could not be stirred. The solution was allowed to settle for 30 minutes and then washed until neutral. The gel was then dried in a conventional oven at 100°C overnight to obtain a solid sample.

[0082] ② The silica-supported nickel salt obtained after drying was fully ground, and the ground powder was calcined at 700°C (heating rate of 5°C / min) in an air atmosphere for 4 hours to obtain the precursor of the catalyst Ni / BMMs.

[0083] 2. Experimental test of the stability of methane dry reforming catalyzed by Ni / BMMs prepared by one-pot method

[0084] The catalyst dosage was 100 mg, with a particle size of 40-60 mesh. Before dry reforming with methane, the system was reduced with 5% H2 / 90% Ar (total flow rate 60 ml / min, reduction temperature from room temperature to 550°C, dwelling at 550°C for 2 hours, heating rate 10°C / min). After the temperature dropped to room temperature, nitrogen was purged for 30 minutes to displace the hydrogen in the system. After the replacement was complete, pure nitrogen was switched to the reaction gas (45 ml CH4: 45 ml CO2: 10 ml N2, space velocity GHSV = 60,000 mL / min). -1 gcat-1 ), then the temperature was raised to 600°C and held for 10 hours at a rate of 10°C / min. The catalyst activity was recorded. The methane conversion was 30.26%, the carbon dioxide conversion was 42.51%, and the H2 / CO ratio was 0.640. Figure 10 As shown ( Figure 10 a: CH4 conversion rate b: CO2 c: conversion rate H2 / CO).

[0085] The results of the performance of catalysts with different loading amounts and different supports prepared by the above method show that Ni / BMMs catalyst has good activity and stability in the methane dry reforming reaction.

[0086] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing a nickel-silicon catalyst suitable for methane dry reforming, characterized in that: The specific steps are as follows: (1) Preparation of nickel silicon catalyst precursor: Preparation of dual-mesoporous silica carrier: Dissolve the template in deionized water at 20-60°C to obtain a first solution. Then slowly add the silicon source dropwise, and then add ammonia as a hydrolysis catalyst and stir continuously until the solution turns into a white gel. Let it settle, then filter and wash the resulting white gel with deionized water, and dry it in a drying oven at 105-120°C to obtain the desired silica carrier. The template agent is one of hexadecyltrimethylammonium bromide, tetraethylammonium hydroxide, triethylamine, and triethanolamine, and the silicon source is one of ethyl orthosilicate and methyl orthosilicate; Silica-supported nickel salt: The nickel active component is loaded onto the silica carrier by an impregnation method, using deionized water as a dispersant. The silica and nickel salt obtained above are dispersed in deionized water, stirred thoroughly for 0.3 to 1.5 hours, and allowed to stand at room temperature for 0.5 to 1 hour. The mixture is then heated and mixed at 20 to 60° C. in a water bath for 4 hours, and the temperature is raised to 70 to 100° C., heated and mixed for 0.5 to 1 hour. The resulting solid powder is dried to obtain the desired nickel-silicon catalyst precursor. (2) calcining the nickel silicon catalyst precursor obtained in step (1) in an air atmosphere at a calcination temperature of 700-750° C., a calcination time of 1-4 h, and a heating rate of 2-20° C. / min.

2. The method according to claim 1, characterized in that The nickel salt is selected from one or more of nickel nitrate hexahydrate, nickel sulfate, nickel chloride, and nickel bromide.

3. The method according to claim 1, characterized in that The nickel loading is between 1% and 20%.

4. The nickel silicon catalyst prepared according to the method according to any one of claims 1 to 3.

5. Use of the nickel silicon catalyst prepared by the method according to any one of claims 1 to 3, characterized in that: Used for medium and low temperature methane dry reforming, catalyzing the reaction of methane and carbon dioxide to produce synthesis gas.

6. The use according to claim 5, characterized in that Catalytic methane dry reforming is performed to produce synthesis gas at 400-900°C. Before the methane dry reforming, hydrogen reduction is performed at a reduction temperature of 350-750°C, with a dwell time of 1-3 hours and a heating rate of 2-20°C / min. The system is then purged with an inert gas for 30 minutes to 1 hour to remove hydrogen. The molar ratio of methane to carbon dioxide in the feed gas for the methane dry reforming is 1:1-3:1, nitrogen is used as the balance gas, and the space velocity (GHSV) is 12,000-60,000 mL / h. -1 gcat -1 .

7. The use according to claim 6, characterized in that The catalytic temperature is 400-900°C, and the catalytic reaction time is 10-100 hours.

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