Core-shell type nano nickel-based catalyst as well as preparation method and application thereof
By preparing a core-shell nano-nickel-based catalyst and using silica and zirconium dioxide as supports and promoters, the problems of high cost and insufficient activity of existing catalysts in the methane-carbon dioxide reforming reaction were solved, achieving high efficiency and stability, and reducing the consumption of metal resources.
Patent Information
- Application Number
- CN202511687544.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-02-24
AI Technical Summary
Existing catalysts for methane-carbon dioxide reforming reactions suffer from high cost, insufficient activity, and inadequate stability. In particular, supported noble metal catalysts are expensive, while non-noble metal catalysts, such as nickel-based catalysts, still need to improve their performance.
Core-shell nickel-based nanocatalysts were prepared using a microemulsion method, with silica as the support and zirconium dioxide as the additive. By forming a SiO2 shell on the surface of nickel particles and covering it with porous zirconium dioxide, the dispersibility and anti-sintering properties of nickel were improved. Combined with high-temperature reduction treatment, a core-shell structure was formed.
This approach achieves high catalyst activity and stability, reduces costs, increases the conversion rate of methane and carbon dioxide, extends catalytic activity time, reduces carbon deposition, and improves catalytic efficiency.
Smart Images
Figure CN121551007A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of transition metal catalyst preparation technology, specifically relating to a core-shell nano-nickel-based catalyst and its preparation method, particularly its application in the reforming of methane-carbon dioxide into syngas. Background Technology
[0002] Carbon dioxide (CO2) is the end product of the combustion of carbon-containing compounds, a byproduct of many chemical production processes, and a major greenhouse gas. With the increasing severity of global environmental problems, CO2 emissions have attracted international attention. Meanwhile, my country has also incorporated CO2 emissions as a binding target into its medium- and long-term national economic and social development plan. Therefore, choosing appropriate CO2 emission reduction pathways under the premise of economic development is urgent. CO2 capture, storage, and utilization have become a hot research topic. Regarding CO2 storage and utilization, economic and risk assessments indicate that CO2 chemical utilization is a direction worthy of vigorous development. Currently, research on the chemical utilization of CO2 mainly includes its use in alkane reforming to produce syngas.
[0003] Dry reforming of methane with carbon dioxide is a promising reaction for producing syngas. First, methane and carbon dioxide are catalytically converted to syngas (H₂ + CO). Then, the syngas is used to produce a series of important chemical feedstocks and liquid fuels. The most important applications include the further synthesis of various liquid fuels and organic chemical feedstocks such as gasoline, diesel, dimethyl ether, ethylene glycol, and olefins via the Fischer-Tropsch reaction.
[0004] Catalyst performance is crucial for the research of methane-carbon dioxide reforming technology. The catalysts used in this reaction are mostly supported catalysts. Supported noble metal catalysts exhibit significantly high activity, high stability, high selectivity, and strong resistance to carbon deposition; however, their high cost limits their widespread use. Nickel-based catalysts, on the other hand, have found widespread application in methane-carbon dioxide dry reforming reactions because their catalytic activity is comparable to that of noble metal catalysts.
[0005] In addition, the support is also a key influencing factor. It can provide physical support for the active component and interact with it, thus affecting the catalyst structure and performance. Currently, commonly used supports include alumina, molecular sieves, and silica. Among them, silica is widely used as a catalyst support due to its stable chemical properties, high melting point, high hardness, high wear resistance (particularly suitable for fluidized bed reactions), large specific surface area, and ease of control over its morphology, size, and pore size. In the field of heterogeneous catalysis, the pores of this porous silica-based material are often used to restrict the growth of metal nanoparticles, improve their anti-sintering properties, and have yielded a wealth of valuable research results.
[0006] Furthermore, the preparation method of nanocatalysts directly affects their structure, particle size distribution, and morphology, thus influencing their catalytic performance. Currently, there are two main methods for preparing nanocatalysts: gas-phase methods and liquid-phase methods. Liquid-phase methods include impregnation, precipitation, sol-gel, and microemulsion methods. Among these, the microemulsion method utilizes two immiscible solvents to form a homogeneous emulsion under the action of a surfactant. A smaller amount of solvent is encapsulated within a larger amount of solvent, forming numerous microbubbles. Within these microbubbles, nanoparticles are obtained through nucleation, aggregation, agglomeration, and heat treatment. Compared to traditional preparation methods, the microemulsion method has significant advantages and is an important means of preparing monodisperse nanoparticles, and it has seen considerable development and improvement in recent years. Summary of the Invention
[0007] To improve catalyst activity and stability, this invention provides a core-shell nano-nickel-based catalyst for carbon dioxide catalytic reforming, along with its preparation and application methods. This catalyst exhibits high activity and stability, and by using inexpensive silica as a support, it achieves cost reduction and conserves metal resources.
[0008] The technical solution of this invention is a core-shell nano-nickel-based catalyst for carbon dioxide reforming. First, a nickel nitrate precursor salt is precipitated as Ni(OH)₂ using a microemulsion method under the action of excess ammonia. A SiO₂ shell is formed around the Ni(OH)₂ precipitate by TEOS hydrolysis. Then, porous zirconium oxide is coated onto the surface of the synthesized SiO₂@Ni. Next, the formed SiO₂@Ni@ZrO₂ sample is heat-treated. Finally, it is reduced at high temperature in an inert or reducing gas to obtain the core-shell nano-nickel-based catalyst.
[0009] Specifically, the catalyst uses silicon dioxide as a carrier, nickel as the active component, and zirconium dioxide as an additive.
[0010] The specific preparation method involves the following steps: 1. Step 1, Preparation of SiO2 support: Tetraethyl orthosilicate and ammonia water are added sequentially to ethanol solution at a volume ratio of 20~40:1~2:2~4. The mixture is stirred at room temperature for 1~2 hours to obtain a white silica gel suspension. The SiO2 support is collected by centrifugation. Step 2, Synthesis of SiO2@Ni: Prepare a Ni(NO3)2·6H2O solution with a concentration of 0.1-0.5 mol / L. Add the SiO2 support obtained in Step 1 to the prepared nickel nitrate solution according to the molar ratio of SiO2 to nickel-containing compound of 1:11-12. Then, stir thoroughly at room temperature for 10-20 min, centrifuge to collect the precipitate, wash the precipitate with ethanol, and dry it at 60-80℃ to obtain solid SiO2@Ni. Step 3, Synthesis of SiO2@Ni@ZrO2: The obtained solid SiO2@Ni is poured into ethanol to obtain a dispersion, and then 0.5% deionized water and surfactant are added sequentially. The mixture is stirred for 20-30 min and mixed evenly. Then, 1% zirconium butoxide is added. After stirring at room temperature for 15-18 h, the mixture is collected by centrifugation and dispersed in deionized water. After standing at room temperature for 1 day, it is washed by centrifugation and dried at 60-80℃ for 12-24 h. Then, it is calcined in air at 500-600℃ for 3-4 h to obtain the solid SiO2@Ni@ZrO2 precursor. Step 4, Core-shell type nano-nickel-based catalyst: Using a high-temperature reduction method, the solid SiO2@Ni@ZrO2 precursor is placed in an inert gas or reducing gas and reduced at a rate of SS℃ / min to 600-800℃ for 1-2 hours, and then naturally cooled to room temperature to obtain the core-shell type nano-nickel-based catalyst.
[0011] All catalysts were compressed into tablets and sieved to obtain 40-60 mesh particles for later use.
[0012] As mentioned above, in step one, the mass concentration of tetraethyl orthosilicate is 98%, and the mass concentration of ammonia is 28.0-30.0%.
[0013] The nickel-containing compound in step two is any one of nickel nitrate hexahydrate, nickel sulfate hexahydrate, nickel sulfate, nickel hydroxy acid, and nickel halide.
[0014] The surfactant mentioned in step three is polyethylene glycol monolaurate ether, with the molecular formula C3. 20 H 42 O5.
[0015] In step three, the mass concentration of zirconium n-butoxide is 20%.
[0016] In step four, the inert gas is nitrogen, helium, neon, argon, krypton, xenon, or a mixture thereof, and the reducing gas is hydrogen, olefins, alkynes, or a mixture thereof.
[0017] The catalyst has a core-shell structure, meaning that the promoter covers the surface of the support, and the active component nickel is uniformly dispersed in the promoter.
[0018] A method of using a core-shell nano-nickel-based catalyst for carbon dioxide catalytic reforming, including a method for use in a methane-carbon dioxide reforming reaction.
[0019] Furthermore, the method for the methane-carbon dioxide reforming reaction includes the following steps: the catalyst is used to undergo a reduction treatment at 600-800°C for 1 hour in an inert or reducing gas atmosphere. After the reduction treatment is completed, the catalyst undergoes a reforming catalytic reaction with methane-carbon dioxide feed gas under the conditions of a reaction pressure of 100 kPa, a reaction temperature of 200-900°C, and a space velocity of 16-72 L / (g·h) to prepare syngas containing H2 and CO.
[0020] Furthermore, in the methane-carbon dioxide reforming reaction at 600–800°C for 0–150 hours, the feed gas is prepared in a methane:carbon dioxide:nitrogen ratio of 1:1:1, with nitrogen serving as the balance gas. The conversion rates of methane and carbon dioxide are 21.52–58.81% and 27.37–59.37%, respectively, and the volume ratio of H2 to CO in the mixed gas is 0.52–0.74.
[0021] The advantages and beneficial effects of this invention are as follows: 1. The catalyst of the present invention has a core-shell structure with silicon dioxide as a support, zirconium dioxide as an auxiliary agent covering its surface, and nickel as an active component dispersed in zirconium dioxide.
[0022] 2. This invention uses silica as a carrier, which is low in cost, widely available, chemically stable, has a high melting point, high hardness, high wear resistance, and large specific surface area. Furthermore, its morphology, size, and pore size are easily controlled, making it widely used as a catalyst carrier.
[0023] 3. In the methane-carbon dioxide catalytic reforming reaction to prepare syngas at 600-800℃ for 0-150 hours, the conversion rates of methane and carbon dioxide can be stably maintained at 21.52-58.81% and 27.37-59.37%, respectively. The conversion rates of methane and carbon dioxide are relatively low compared with the prior art, and there is no significant improvement. What is the significant improvement of the catalyst of this invention?
[0024] 4. In the methane-carbon dioxide reforming reaction to prepare syngas at 600-800℃ for 0-150 hours, the gas volume ratio of H2 to CO in the mixed gas is 0.52-0.74.
[0025] 5. The SiO2@Ni@ZrO2 synthesized in this invention is heat-treated before high-temperature reduction in an inert or reducing gas to burn and decompose the residual organic ligands on its surface.
[0026] 6. The SiO2@Ni catalyst with added zirconium dioxide as an additive will highly disperse the active component nickel, thereby reducing the particle size of nickel and achieving the purpose of preventing nickel sintering in the catalytic reaction.
[0027] 7. The SiO2@Ni catalyst with added zirconium dioxide exhibits anti-carbon deposition properties in the catalytic reaction compared to the SiO2@Ni catalyst without added zirconium dioxide.
[0028] 8. When nickel-loaded active components of silica with added additives are reduced by high temperature, the nickel compounds are reduced on the one hand, and the silica support is prepared into a silica support with regular morphology, high specific surface area and simple chemical composition that is loaded with nickel active components.
[0029] 9. The core-shell nano-nickel-based catalyst prepared by this invention is a structure with silica as a support, an additive covering the surface of the support, and metallic nickel dispersed in the additive. In the methane-carbon dioxide catalytic reforming reaction, its catalytic efficiency is higher than that of the SiO2@Ni catalyst without additive.
[0030] 10. The core-shell nano-nickel-based catalyst prepared in this invention exhibits excellent performance in the methane-carbon dioxide catalytic reforming reaction. Due to the addition of zirconium dioxide as a promoter to the SiO2@Ni catalyst, the catalyst does not accumulate carbon during the methane-carbon dioxide reforming reaction and maintains its catalytic activity for a long time, up to 150 hours. Attached Figure Description
[0031] Figure 1 This is a transmission electron microscope (TEM) image of the catalyst obtained in Example 1 of the present invention. Figure 2 The XRD patterns are those of the nickel nano-catalyst obtained in Example 4 without the additive zirconium dioxide and the core-shell nickel nano-catalyst obtained in Example 5 of this invention. Figure 3 The changes in CH4 and CO2 conversion rates and hydrogen-to-carbon ratio over time of the core-shell nickel-based nano-catalyst prepared by the present invention in the methane-carbon dioxide catalytic reforming reaction in Example 1; Figure 4 The changes in CH4 and CO2 conversion rates and hydrogen-to-carbon ratio over time of the core-shell nickel-based nano-catalyst prepared by the present invention in the methane-carbon dioxide catalytic reforming reaction are shown in Example 2. Figure 5 The changes in CH4 and CO2 conversion rates and hydrogen-to-carbon ratio over time of the core-shell nickel-based nano-catalyst prepared by the present invention in the methane-carbon dioxide catalytic reforming reaction are shown in Example 3. Figure 6 The changes in CH4 and CO2 conversion rates and hydrogen-to-carbon ratio over time in the methane-carbon dioxide catalytic reforming reaction using a nano-nickel-based catalyst without zirconium dioxide additives, as shown in Case Study 4. Figure 7 The variation of CH4 and CO2 conversion rates and hydrogen-to-carbon ratio over time in the methane-carbon dioxide catalytic reforming reaction of the core-shell nano-nickel-based catalyst prepared in this invention in Example 5 is shown. Detailed Implementation
[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.
[0033] This invention provides a core-shell nickel-based nanocatalyst for carbon dioxide reforming reactions. First, a nickel nitrate precursor salt is precipitated as Ni(OH)₂ using a microemulsion method under the action of excess ammonia. A SiO₂ shell is formed around the Ni(OH)₂ precipitate by TEOS hydrolysis. Then, porous zirconium oxide is coated onto the surface of the synthesized SiO₂@Ni. Next, the formed SiO₂@Ni@ZrO₂ sample is heat-treated. Finally, it is reduced at high temperature in an inert or reducing gas to obtain the core-shell nickel-based nanocatalyst.
[0034] Example 1 Catalyst preparation: (1) Add 1 mL of tetraethyl orthosilicate to 20 mL of ethanol, then add 2 mL of NH3·H2O with a mass concentration of 28%, stir the mixture at room temperature for 1 h to obtain a white silica gel suspension, and collect the SiO2 support by centrifugation.
[0035] (2) Weigh the Ni(NO3)2·6H2O precursor salt and dissolve it completely in deionized water to prepare 2 mL of 0.2 mol / mL Ni(NO3)2·6H2O solution. Add the SiO2 support obtained in step (1) to the prepared nickel nitrate solution and stir thoroughly at room temperature for 10 min to obtain solution A. After centrifuging solution A to collect the precipitate, wash it three times with ethanol and dry it at 70℃ to obtain solid SiO2@Ni.
[0036] (3) The solid SiO2@Ni obtained in step (2) was dissolved in 20 mL of ethanol, and then 0.1 mL of deionized water and 0.1 mL of surfactant (ethylene glycol monolaurate ether) were added. The mixture was stirred for 30 min to obtain solution B. 0.2 mL of 20% zirconium butoxide was added to solution B and stirred at room temperature for 16 h to obtain solution C. Solution C was collected by centrifugation and redispersed with 20 mL of deionized water. After standing for 1 day, solution D was obtained. Solution D was collected by centrifugation and washed 3 times with deionized water. It was then dried at 70 °C for 24 h to obtain solid C. Solid C was calcined in air at 550 °C for 3 h by high-temperature calcination to obtain solid D.
[0037] (4) Take the solid D obtained in step (3) and put it into a quartz reaction tube with an outer diameter of 1 inch. Use a programmable temperature-controlled heating tube furnace, with the heating rate controlled at 10℃ / min. Heat it to 700℃ in a nitrogen gas flow containing 10% hydrogen at a flow rate of 50 mL / min. After holding it at the temperature for 1 hour, wait for the temperature to drop to room temperature to obtain the desired core-shell nano nickel-based catalyst.
[0038] Evaluation of catalysts in carbon dioxide reforming reactions: 75 mg of the catalyst prepared in step (4) was fed into a quartz tube reactor with an outer diameter of 1 inch. It was heated to 700°C for 1 hour in a nitrogen gas flow of 100 mL / min containing 10% hydrogen. The reducing gas flow was then stopped, and the gas was switched to methane, carbon dioxide, and nitrogen, with nitrogen serving as the balance gas. Under these conditions, the catalyst activity was evaluated, and the results are as follows: Figure 5 The reaction conditions were: temperature 700℃, pressure 100 kPa, feed gas ratio of 1:1:1, flow rate of 10 mL / min, and gas hourly space velocity (GHSV) of 24 L / (g·h). The conversion rates of methane and carbon dioxide were 50.71~58.81% and 48.55~59.37%, respectively, and the volume ratio of H2 to CO in the mixed gas was 0.64~0.74.
[0039] Example 2 Catalyst preparation: (1) Add 1.25 mL of tetraethyl orthosilicate to 25 mL of ethanol, then add 2.5 mL of NH3·H2O. Stir the mixture at room temperature for 1 h to obtain a white silica gel suspension. Collect the SiO2 support by centrifugation.
[0040] (2) Weigh a certain amount of Ni(NO3)2·6H2O precursor salt, dissolve it completely in deionized water, and prepare 2.5 mL of 0.3 mol / mL Ni(NO3)2·6H2O solution. Take the SiO2 support obtained in step (1) and add it to the prepared nickel nitrate solution. Then stir it thoroughly at room temperature for 15 min to obtain solution A. After centrifuging solution A, wash it three times with ethanol and dry it at 60℃ to obtain solid SiO2@Ni.
[0041] (3) Dissolve the solid SiO2@Ni obtained in step (2) in 25 mL of ethanol, then add 0.12 mL of deionized water and 0.12 mL of surfactant, and stir for 25 min to obtain solution B. Add 0.25 mL of zirconium butoxide to solution B and stir at room temperature for 15 h to obtain solution C. After centrifuging solution C, redisperse it with 25 mL of deionized water, and let it stand for 1 day to obtain solution D. After centrifuging again, wash it 4 times with deionized water, and dry it at 60 °C for 24 h to obtain solid C. Calcine solid C in air at 500 °C for 4 h using a high-temperature calcination method to obtain solid D.
[0042] (4) Take the solid D obtained in step (3) and put it into a quartz reaction tube with an outer diameter of 1 inch. Use a programmable temperature-controlled heating tube furnace, with the heating rate controlled at 12℃ / min. Heat to 600℃ in an argon gas flow of 60 mL / min. After holding at the temperature for 2 hours, wait for the temperature to drop to room temperature to obtain the desired core-shell nano nickel-based catalyst.
[0043] Evaluation of catalysts in carbon dioxide reforming reactions: 150 mg of the catalyst prepared in step (4) was fed into a quartz tube reactor with an outer diameter of 1 inch and heated to 600 °C for 2 hours in an argon gas flow of 60 mL / min. When the temperature reached 650 °C, the reducing gas flow was stopped, and methane, carbon dioxide, and nitrogen were introduced, with nitrogen used as the balance gas. Under these conditions, the catalyst activity was evaluated, and the results are as follows: Figure 5 The reaction conditions were: temperature 650℃, pressure 100 kPa, feed gas ratio of 1:1:1, flow rate of 40 mL / min, and gas hourly space velocity (GHSV) of 48 L / (g·h). The conversion rates of methane and carbon dioxide were 31.98~39.35% and 36.54~46.39%, respectively, and the volume ratio of H2 to CO in the mixed gas was 0.59~0.69.
[0044] Example 3 Catalyst preparation: (1) Add 1.5 mL of tetraethyl orthosilicate to 30 mL of ethanol, then add 3 mL of NH3·H2O, stir the mixture at room temperature for 1 h to obtain a white silica gel suspension, and collect the SiO2 support by centrifugation.
[0045] (2) Weigh a certain amount of Ni(NO3)2·6H2O precursor salt, dissolve it completely in deionized water, and prepare 3 mL of 0.4 mol / mL Ni(NO3)2·6H2O solution. Add the SiO2 support obtained in step (1) to the prepared nickel nitrate solution, and then stir thoroughly at room temperature for 10 min to obtain solution A. After centrifuging solution A, wash it 4 times with ethanol, and dry it at 65℃ to obtain solid SiO2@Ni.
[0046] (3) The solid SiO2@Ni obtained in step (2) was dissolved in 30 mL of ethanol, and then 0.15 mL of deionized water and 0.15 mL of surfactant were added and stirred for 25 min to obtain solution B. 0.3 mL of n-butoxide zirconium was added to solution B and stirred at room temperature for 16 h to obtain solution C. Solution C was collected by centrifugation and redispersed with 30 mL of deionized water. After standing for 1 day, solution D was obtained. After centrifugation, solution D was collected and washed 4 times with deionized water and dried at 65 °C for 24 h to obtain solid C. Solid C was obtained by high-temperature calcination and calcination at 500 °C for 4 h in air to obtain solid D.
[0047] (4) Take the solid D obtained in step (3) and put it into a quartz reaction tube with an outer diameter of 1 inch. Use a programmable temperature-controlled heating tube furnace, with the heating rate controlled at 15℃ / min. Heat to 650℃ in a neon gas flow of 10% hydrogen at 70mL / min. After holding at the temperature for 2 hours, wait for the temperature to drop to room temperature to obtain the desired core-shell nano nickel-based catalyst.
[0048] Evaluation of catalysts in carbon dioxide reforming reactions: 100 mg of the catalyst prepared in step (4) was fed into a quartz tube reactor with an outer diameter of 1 inch. It was heated to 650 °C for 2 hours in a neon gas flow containing 10% hydrogen at a rate of 70 mL / min. When the temperature dropped to 600 °C, the reducing gas flow was stopped, and methane, carbon dioxide, and nitrogen were introduced, with nitrogen used as the balance gas. Under these conditions, the catalyst activity was evaluated, and the results are as follows: Figure 5 The reaction conditions were: temperature 600℃, pressure 100 kPa, feed gas ratio of 1:1:1, flow rate of 20 mL / min, and reaction space velocity (GHSV) of 36 L / (g·h). The conversion rates of methane and carbon dioxide were 21.52~30.82% and 27.37~38.93%, respectively, and the volume ratio of H2 to CO in the mixed gas was 0.52~0.61.
[0049] Example 4 Catalyst preparation: (1) Add 1.75 mL of tetraethyl orthosilicate to 35 mL of ethanol, then add 3.5 mL of NH3·H2O. Stir the mixture at room temperature for 2 h to obtain a white silica gel suspension. Collect the SiO2 support by centrifugation.
[0050] (2) Weigh a certain amount of NiSO4·6H2O precursor salt, dissolve it completely in deionized water, and prepare 3.5 mL of 0.5 mol / mL NiSO4·6H2O solution. Take the SiO2 support obtained in step (1) and add it to the prepared nickel nitrate solution. Then stir it thoroughly at room temperature for 18 min to obtain solution A. After centrifuging solution A, wash it 5 times with ethanol and dry it at 75℃ to obtain solid SiO2@Ni.
[0051] (3) The solid SiO2@Ni obtained in step (2) is calcined in air at 600°C for 3 hours by high-temperature calcination to obtain solid nitrile.
[0052] (4) Take the solid D obtained in step (3) and put it into a quartz reaction tube with an outer diameter of 1 inch. Use a programmable temperature-controlled heating tube furnace, with the heating rate controlled at 18℃ / min. Heat to 750℃ in a helium gas flow of 80mL / min. After holding at the temperature for 1 hour, wait for the temperature to drop to room temperature to obtain the desired nano-nickel-based catalyst.
[0053] Evaluation of catalysts in carbon dioxide reforming reactions: 75 mg of the catalyst prepared in step (4) was fed into a quartz tube reactor with an outer diameter of 1 inch and heated to 750°C for 1 hour in a helium gas stream. The reducing gas was then stopped, and methane, carbon dioxide, and nitrogen were introduced, with nitrogen serving as the equilibrium gas. The reaction was carried out under these conditions for 20 hours, and the catalyst activity was evaluated. The evaluation results are as follows: Figure 5 The reaction conditions were: temperature 750℃, pressure 100 kPa, feed gas ratio of 1:1:1, flow rate of 30 mL / min, and gas hourly space velocity (GHSV) of 72 L / (g·h). The conversion rates of methane and carbon dioxide were 30.80~35.39% and 41.81~45.71%, respectively, and the volume ratio of H2 to CO in the mixed gas was 0.68~0.72.
[0054] Example 5 Catalyst preparation: (1) Add 2 mL of tetraethyl orthosilicate to 40 mL of ethanol, then add 4 mL of NH3·H2O, stir the mixture at room temperature for 2 h to obtain a white silica gel suspension, and collect the SiO2 support by centrifugation.
[0055] (2) Weigh a certain amount of NiSO4·6H2O precursor salt, dissolve it completely in deionized water, and prepare 4 mL of 0.35 mol / mL NiSO4·6H2O solution. Add the SiO2 support obtained in step (1) to the prepared nickel nitrate solution, and then stir thoroughly at room temperature for 20 min to obtain solution A. After centrifuging solution A, wash it 5 times with ethanol, and dry it at 80℃ to obtain solid SiO2@Ni.
[0056] (3) The solid SiO2@Ni obtained in step (2) was dissolved in 40 mL of ethanol, and then 0.2 mL of deionized water and 0.2 mL of surfactant were added and stirred for 30 min to obtain solution B. 0.4 mL of n-butoxide zirconium was added to solution B and stirred at room temperature for 18 h to obtain solution C. Solution C was collected by centrifugation and redispersed with 40 mL of deionized water. After standing for 1 day, solution D was obtained. After centrifugation and collection, it was washed 5 times with deionized water and dried at 80 °C for 24 h to obtain solid C. Solid C was obtained by high-temperature calcination and calcination at 600 °C for 3 h in air to obtain solid D.
[0057] (4) Take the solid D obtained in step (3) and put it into a quartz reaction tube with an outer diameter of 1 inch. Use a programmable temperature-controlled heating tube furnace, with the heating rate controlled at 20℃ / min. Heat it to 800℃ in a 90 mL / min flow of neon containing 3% hydrogen. After holding it at that temperature for 1 hour, wait for the temperature to drop to room temperature to obtain the desired core-shell nano nickel-based catalyst.
[0058] Evaluation of catalysts in carbon dioxide reforming reactions: Take 50 mg of the catalyst prepared in step (4) and feed it into a quartz tube reactor with an outer diameter of 1 inch. Heat to 800°C for 1 hour in a neon gas stream. Stop the reducing gas supply and switch to methane, carbon dioxide, and nitrogen, with nitrogen serving as the equilibrium gas. React under these conditions for 20 hours, and then evaluate the catalyst's activity. The evaluation results are as follows: Figure 5The reaction conditions are: temperature 800℃, pressure 100KPa, feed gas ratio of 1:1:1, flow rate of 20 mL / min, and reaction space velocity (GHSV) of 72 L / (g‧h). The conversion rates of methane and carbon dioxide are 30.30~39.97% and 38.65~47.43%, respectively, and the volume ratio of H2 to CO in the mixed gas is 0.60~0.65. The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the invention.
Claims
1. A core-shell nano-nickel-based catalyst for carbon dioxide reforming reactions, characterized in that, First, tetraethyl orthosilicate (TEOS) is synthesized and treated to obtain a silica support. SiO2@Ni is then prepared by microemulsion method. Next, zirconium dioxide additive is coated on the surface of the synthesized SiO2@Ni. Then, the formed SiO2@Ni@ZrO2 sample is heat-treated. Finally, a high-temperature reduction method is used in an inert gas or reducing gas to obtain a core-shell nano-nickel-based catalyst.
2. The core-shell nano-nickel-based catalyst as described in claim 1, characterized in that, The catalyst uses silicon dioxide as a carrier, nickel as the active component, and zirconium dioxide as an additive.
3. A method for preparing a core-shell type nickel-based nanocatalyst for carbon dioxide reforming reaction, characterized in that, The catalyst as described in claims 1 to 2 is prepared by the following steps: Step 1, preparation of SiO2 support: Tetraethyl orthosilicate and ammonia are added sequentially to an ethanol solution at a volume ratio of 20~40:1~2:2~4. The mixture is stirred at room temperature for 1~2 hours to obtain a white silica gel suspension, which is then collected by centrifugation to obtain the SiO2 support. Step 2, Synthesis of SiO2@Ni: Prepare a Ni(NO3)2·6H2O solution with a concentration of 0.1-0.5 mol / L. Add the SiO2 support obtained in Step 1 to the prepared nickel nitrate solution according to the molar ratio of SiO2 to nickel-containing compound of 1:11-12. Then, stir thoroughly at room temperature for 10-20 min, centrifuge to collect the precipitate, wash the precipitate with ethanol, and dry it at 60-80℃ to obtain solid SiO2@Ni. Step 3, Synthesis of SiO2@Ni@ZrO2: The obtained solid SiO2@Ni is poured into ethanol to obtain a dispersion, and then 0.5% deionized water and surfactant are added sequentially. The mixture is stirred for 20-30 min and mixed evenly. Then, 1% zirconium butoxide is added. After stirring at room temperature for 15-18 h, the mixture is collected by centrifugation and dispersed in deionized water. After standing at room temperature for 1 day, it is washed by centrifugation and dried at 60-80℃ for 12-24 h. Then, it is calcined in air at 500-600℃ for 3-4 h to obtain the solid SiO2@Ni@ZrO2 precursor. Step 4, Core-shell type nano-nickel-based catalyst: Using a high-temperature reduction method, the solid SiO2@Ni@ZrO2 precursor is placed in an inert gas or reducing gas and reduced at a rate of SS℃ / min to 600-800℃ for 1-2 hours, and then naturally cooled to room temperature to obtain the core-shell type nano-nickel-based catalyst.
4. The method for preparing a core-shell nano-nickel-based catalyst for carbon dioxide reforming reaction as described in claim 3, characterized in that: In step one, the mass concentration of tetraethyl orthosilicate is 98%, and the mass concentration of ammonia is 28.0%–30.0%.
5. The method for preparing a core-shell nano-nickel-based catalyst for carbon dioxide reforming reaction as described in claim 3, characterized in that: The nickel-containing compound in step two is any one of nickel nitrate hexahydrate, nickel sulfate hexahydrate, nickel sulfate, nickel hydroxy acid, and nickel halide.
6. The method for preparing a core-shell nano-nickel-based catalyst for carbon dioxide reforming reaction as described in claim 3, characterized in that: The surfactant mentioned in step three is polyethylene glycol monolaurate ether, with the molecular formula C3. 20 H 42 O5.
7. The method for preparing a core-shell nano-nickel-based catalyst for carbon dioxide reforming reaction as described in claim 3, characterized in that: In step three, the mass concentration of zirconium n-butoxide is 20%.
8. A method of using a core-shell nano-nickel-based catalyst for carbon dioxide catalytic reforming, including a method for use in a methane-carbon dioxide reforming reaction.
9. The method of using the core-shell nano-nickel-based catalyst for carbon dioxide catalytic reforming as described in claim 7, characterized in that, The method for methane-carbon dioxide reforming reaction includes the following steps: using the catalyst described in any one of claims 1 to 3, a reduction treatment is performed at 600-800°C for 1-2 hours in an inert or reducing gas atmosphere. After the reduction treatment is completed, a reforming catalytic reaction is carried out with methane-carbon dioxide feed gas under the conditions of a reaction pressure of 100 kPa, a reaction temperature of 200-900°C, and a space velocity of 16-72 L / (g·h) to prepare syngas containing H2 and CO.
10. The method of using the core-shell nano-nickel-based catalyst for carbon dioxide catalytic reforming as described in claim 7, characterized in that: In the methane-carbon dioxide reforming reaction at 600–800°C for 0–150 hours, the feed gas is prepared in a methane:carbon dioxide:nitrogen ratio of 1:1:1, with nitrogen serving as the equilibrium gas. The conversion rates of methane and carbon dioxide are 21.52–58.81% and 27.37–59.37%, respectively, and the volume ratio of H2 to CO in the mixed gas is 0.52–0.74.