Nickel-based catalyst, preparation method thereof and application of nickel-based catalyst in methane dry gas reforming reaction
By loading molybdenum salt additives on the carrier of the nickel -based catalyst, the use limit effect and dynamic conversion mechanism are used to solve the problem of carbon deposition in the reactions of nickel catalysts in the reactions of the methane dry gas, realizing the high stability of the catalyst The performance of the carbon resistance has extended the service life and improved the reaction efficiency.
Patent Information
- Application Number
- CN202411473879.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-01-24
AI Technical Summary
Nickel-based catalysts are prone to carbon deposition during methane dry gas reforming reaction, resulting in a decrease in catalytic activity and hindering industrial application.
By loading molybdenum salt additives on the carrier, the dynamic conversion mechanism of MOOX and MOOXCY is used to promote the uniform dispersing nickel and the removal of carbon accumulation.
It significantly improves the stability of catalysts and carbon resistance, prolongs the service life of the catalyst, and improves the efficiency of the reaction of methane dry gas.
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Figure CN119346162A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalyst preparation, and in particular to a nickel-based catalyst and a preparation method thereof and application thereof in a methane dry gas reforming reaction. Background Art
[0002] Carbon dioxide (CO2) and methane (CH4) are the main greenhouse gases, and their continued growth in emissions has exacerbated the severe challenges of global warming and climate change. To address this issue, carbon capture, utilization and storage (CCUS) technology, especially the dry methane reforming reaction (DRM) that converts these two gases into high-value chemicals, has become a major research hotspot. The DRM reaction aims to convert CO2 and CH4 into synthesis gas with a H2 / CO ratio close to one, and then produce value-added chemicals through processes such as Fischer-Tropsch synthesis, which is of great significance to mitigating the greenhouse effect.
[0003] However, the DRM reaction is highly dependent on the performance of the catalyst. Traditionally, although precious metal catalysts have shown high activity, their high cost and limited resources have limited their large-scale application. In contrast, nickel-based catalysts have become the subject of extensive research due to their low cost and strong CH bond breaking ability. However, a major bottleneck of nickel-based catalysts in the DRM reaction is the carbon deposition problem, that is, carbon deposits are easily formed on the catalyst surface, covering the active sites, resulting in a sharp drop in catalytic activity, which hinders industrial application.
[0004] Therefore, it is urgent to provide a solution to solve the above problems. Summary of the invention
[0005] The present invention aims to provide a nickel-based catalyst and a preparation method thereof and application thereof in a methane dry gas reforming reaction. The catalyst utilizes a confinement effect to highly disperse the auxiliary agent molybdenum in a carrier, thereby strengthening the anchoring effect on the active component nickel and promoting the uniform dispersion of nickel. x with MoO x C y The dynamic conversion mechanism accelerates the removal of carbon deposits during the reaction and effectively improves the stability and anti-carbon deposition performance of the catalyst.
[0006] In a first aspect, the present invention provides a nickel-based catalyst, comprising a base core and an additive loaded on the base core, the base core comprising a porous carrier and a nickel precursor loaded in the pores of the porous carrier, the additive comprising a molybdenum salt, the porous carrier comprising a Z5 molecular sieve, and the nickel precursor comprising a nickel salt and a chelating agent.
[0007] In fact, the additive is highly dispersed on the Z5 molecular sieve framework. The addition of the additive can strengthen the strong interaction between the carrier and the active component nickel, greatly promoting the dispersion of nickel, thereby achieving continuous and efficient carbon removal in the methane dry gas reforming reaction.
[0008] Optionally, the Z5 molecular sieve comprises a structure directing agent, a silicon source and an aluminum source, wherein the structure directing agent comprises TPAOH, the silicon source is selected from tetraethyl orthosilicate, and the aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sulfate and aluminum chloride.
[0009] Optionally, the TPAOH is alkaline to create an alkaline reaction environment.
[0010] Optionally, the molar ratio of the structure directing agent, the silicon source and the aluminum source is 1:(0.05-0.04):(0.05-0.04).
[0011] Optionally, the nickel salt includes at least one of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate.
[0012] Optionally, the nickel element in the nickel precursor accounts for 1.0wt%-10.0wt% of the mass of the Z5 molecular sieve.
[0013] Optionally, the chelating agent is ethylenediamine.
[0014] Optionally, the molybdenum salt includes at least one of sodium molybdate, ammonium molybdate and ammonium heptamolybdate.
[0015] Optionally, the molybdenum element in the molybdenum salt accounts for 0.5wt%-5.0wt% of the mass of the Z5 molecular sieve.
[0016] In a second aspect, the present invention provides a method for preparing the above catalyst, comprising the following steps:
[0017] The nickel precursor and Z5 molecular sieve are subjected to hydrothermal crystallization reaction to obtain the base core;
[0018] The base core and the molybdenum salt are subjected to a hydrothermal crystallization reaction to obtain a catalyst precursor; the catalyst precursor is reduced to obtain a nickel-based catalyst.
[0019] The catalyst preparation method provided by the present invention solves the problem that the active component nickel of the catalyst is easily sintered to produce carbon deposits during the reaction by loading an auxiliary agent on the carrier to strengthen the strong interaction between the carrier and nickel, and can effectively improve the service life of the catalyst.
[0020] Optionally, the hydrothermal crystallization reaction of the nickel precursor and the Z5 molecular sieve includes: mixing the nickel precursor and the Z5 molecular sieve and stirring for 1 h-2 h, then pouring into a reaction kettle, and placing in an oven at 170° C.-180° C. for reaction for 2 d-4 d.
[0021] Optionally, the hydrothermal crystallization reaction of the base core and the molybdenum salt includes: mixing the base core and the molybdenum salt and stirring for 5h-7h, then pouring into a reaction kettle, and placing in an oven at 60°C-120°C for reaction for 4d-6d.
[0022] Optionally, after the nickel precursor and the Z5 molecular sieve are subjected to a hydrothermal crystallization reaction and the base core and the molybdenum salt are subjected to a hydrothermal crystallization reaction, the base core and the catalyst precursor are subjected to a washing, drying and calcining treatment, including: washing the base core and the catalyst precursor with pure water and ethanol for 3 to 5 times, placing them in an oven at 70°C to 100°C, and drying them for 3 to 5 times. o C for 5h-7h and calcined in a muffle furnace at 400℃-800℃ for 2h-10h.
[0023] The catalyst precursor is subjected to high-temperature calcination treatment to convert the nickel precursor into nickel oxide, thereby forming a strong interaction with the carrier, and finally preparing a nickel-based catalyst with specific strong stability.
[0024] The third invention provides the use of the catalyst prepared by any of the above optional preparation methods in a methane dry gas reforming reaction.
[0025] Optionally, at 500°C-800°C, methane and carbon dioxide are reacted with a catalyst to generate carbon monoxide and hydrogen.
[0026] The catalyst provided by the present invention can significantly improve the efficiency and stability of the reaction due to its excellent catalytic performance in the efficient hydrogen production application of methane dry gas reforming technology, providing a new way for the efficient utilization of natural gas and the realization of dual carbon goals, and highly consistent with the high standards of the industrial production field for long-term performance stability and high-efficiency utilization. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly introduce the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.
[0028] Figure 1 ATR-FTIR spectra of the catalyst and base core prepared in Example 1 of the present invention;
[0029] Figure 2 The methane conversion rate of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention in the methane dry gas reforming reaction at 500° C. to 800° C.;
[0030] Figure 3 The Raman spectra of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention after being subjected to methane dry gas reforming reaction at 600° C. for 30 hours;
[0031] Figure 4 The TGA-DSC graphs of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention after being subjected to methane dry gas reforming reaction at 600° C. for 30 hours. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described through the following embodiments in conjunction with the accompanying drawings. However, the following embodiments are illustrative and are only used to specifically describe the present invention rather than to limit the present invention.
[0033] The present invention provides a nickel-based catalyst, which includes a base core and an auxiliary agent loaded in pores of the base core, the base core includes a porous carrier and a nickel precursor loaded in the pores of the porous carrier, the auxiliary agent includes a molybdenum salt, the porous carrier includes a Z5 molecular sieve, and the nickel precursor includes a nickel salt and a chelating agent.
[0034] In some embodiments, the Z5 molecular sieve includes a structure directing agent, a silicon source and an aluminum source, wherein the structure directing agent includes TPAOH, the silicon source is selected from tetraethyl orthosilicate, and the aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sulfate and aluminum chloride.
[0035] In some embodiments, the molar ratio of the structure directing agent, the silicon source, and the aluminum source is 1:(0.05-0.04):(0.05-0.04).
[0036] In some embodiments, the nickel salt includes at least one of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate.
[0037] In some embodiments, the nickel element in the nickel precursor accounts for 1.0wt%-10.0wt% of the mass of the Z5 molecular sieve.
[0038] In some embodiments, the chelating agent is ethylenediamine.
[0039] In some embodiments, the molybdenum salt includes at least one of sodium molybdate, ammonium molybdate, and ammonium heptamolybdate.
[0040] In some embodiments, the molybdenum element in the molybdenum salt accounts for 0.5 wt%-5.0 wt% of the mass of the Z5 molecular sieve.
[0041] The present invention also provides a method for preparing the catalyst, comprising the following steps:
[0042] S1, subjecting a nickel precursor to a hydrothermal crystallization reaction with a Z5 molecular sieve to obtain a base core;
[0043] S2. A catalyst precursor is prepared by subjecting the base core and a molybdenum salt to a hydrothermal crystallization reaction; and the catalyst precursor is reduced to prepare a nickel-based catalyst.
[0044] In fact, when executing step S1, the following sub-steps are included:
[0045] S1.1, first stir the structure directing agent and aluminum source in water until it is clear, then slowly add the silicon source and stir at room temperature for 3h-5h to prepare the Z5 molecular sieve;
[0046] S1.2. Mix the nickel precursor and Z5 molecular sieve and stir for 1h-2h, then pour into a reactor and place in an oven at 170℃-180℃ for reaction for 2d-4d to obtain a base core. Wash, dry and calcine the base core to obtain a base core powder.
[0047] In fact, when executing step S2, the following sub-steps are included:
[0048] S2.1. After ultrasonically dispersing the base core powder in water for 30-40 minutes, add molybdenum salt and stir for 5-7 hours, then pour into a reactor and place in an oven at 60-120°C for 4-6 days to obtain a solid catalyst;
[0049] S2.2. Wash, dry and calcine the solid catalyst to obtain a nickel-based catalyst.
[0050] In some embodiments, when performing step S1.2 and step S2.2, washing includes washing with pure water and ethanol for 3-5 times, drying includes drying in an oven at 70°C-100°C for 5h-7h, and calcining includes calcining in a muffle furnace at 400oC-800°C for 2h-10h.
[0051] The present invention also provides an application of the catalyst in a methane dry gas reforming reaction, comprising:
[0052] At 500℃-800℃, methane and carbon dioxide generate carbon monoxide and hydrogen over the action of nickel-based catalysts.
[0053] Example 1
[0054] Embodiment 1 of the present invention provides a method for preparing a nickel-based catalyst, comprising the following steps:
[0055] S1.1. Dissolve 4 g of TPAOH (CAS: 4499-86-9) and 0.4 g of sodium aluminate in deionized water, stir until the solution is clear and transparent, slowly drop 2 g of tetraethyl orthosilicate (CAS: 78-10-4) and stir at room temperature for 4 h to obtain Z5 molecular sieve; mix 0.1 g of nickel nitrate hexahydrate (CAS: 13478-00-7) and 2 mL of ethylenediamine (CAS: 107-15-3) and ultrasonically treat for 30 min to obtain a nickel precursor;
[0056] S1.2, 0.4g nickel precursor was poured into 2g Z5 molecular sieve and stirred for 1h, then transferred to a high-pressure reactor and placed in an oven at 170℃ for crystallization for 3d. The crystallized sample was centrifugally washed and placed in an oven at 80℃ for drying for 6h. The dried solid sample was ground into powder and calcined in a muffle furnace at 550℃ for 6h to obtain purified Ni@Z5 core powder;
[0057] S2.1. After ultrasonically dispersing 1 g of Ni@Z5 powder in 40 mL of deionized water for 35 min, 0.5 g of sodium molybdate was added and stirred vigorously for 6 h. The mixture was transferred to a high-pressure reactor and crystallized in an oven at 90 °C for 5 days to obtain a solid catalyst.
[0058] S2.2. After centrifugal washing, the solid catalyst was placed in an oven and dried at 80°C for 6 h. The dried solid sample was ground into powder and calcined in a muffle furnace at 550°C for 6 h to obtain a purified nickel-based catalyst (Ni@Mo-Z5).
[0059] In a fixed bed reactor, the catalyst was reduced in situ at 75 °C for 2 h with a 10% H2-Ar mixed gas at a flow rate of 30 mL / min. The reduced Ni@Mo-Z5 catalyst and Ni@Z5 core were characterized by FTIR-ATR. The results are shown in Figure 1 As shown: Both catalysts have -1 The peak at 1061 cm-1 corresponds to the vibration of Si-O-Al framework. -1 The phenomenon of broadening is shown at the center, which corresponds to the vibration of Si-O-Mo framework, proving that Mo has successfully entered into the framework of Z5 molecular sieve and the metal Mo confined Ni@Mo-Z5 catalyst has been successfully prepared.
[0060] Comparative Example 1
[0061] Comparative Example 1 of the present invention provides a method for preparing a nickel-based catalyst. Compared with Example 1, Comparative Example 1 only performs the reaction of steps S1.1 to S1.2 to finally prepare a nickel-based catalyst (Ni@Z5).
[0062] Comparative Example 2
[0063] Comparative Example 1 of the present invention provides a method for preparing a nickel-based catalyst. Compared with Example 1, ammonium molybdate tetrahydrate is used instead of sodium molybdate in step S2, and water bath evaporation is used instead of oven crystallization; finally, a nickel-based catalyst (Mo / Ni@Z5) is prepared.
[0064] Activity test
[0065] The catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 were respectively used for methane dry gas reforming reaction:
[0066] First, the powder was sieved through a pressed tablet to 60 mesh to prepare a granular catalyst. 50 mg of the catalyst was loaded into a quartz tube with an inner diameter of 6 mm and blocked at both ends with quartz wool. The catalyst was heated from room temperature to 750 ° C in a 10% H2 / Ar atmosphere with a space velocity of 30 mL / min and maintained for 2 h. After the reduction was completed, the reaction gas (CH4:CO2 = 1:1, WHSV = 18,000 mL g cat -1 h -1 , p = 1atm), during the temperature rise from 500℃ to 800℃, the methane conversion rates of the three catalysts were tested at each 50℃ drop in temperature. The results are as follows Figure 2 shown.
[0067] The results showed that the catalytic activities of Ni@Mo-Z5 catalyst, Ni@Z5 catalyst and Mo / Ni@Z5 catalyst were slightly stronger than that of Ni@Z5 catalyst, while the catalytic activity of Ni@Mo-Z5 catalyst was the best among the three catalysts.
[0068] Characterization analysis
[0069] Raman characterization was performed on the three catalysts for methane dry gas reforming reaction at 600℃ for 30h. The results are as follows Figure 3 The results show that the Ni@Z5 catalyst and the Mo / Ni@Z5 catalyst have -1 and 1600cm -1 There are peaks on the left and right, corresponding to the peaks of amorphous carbon (D band) and graphite carbon (G band), respectively, while no D band or G band peaks were detected in the Raman spectrum of the Ni@Mo-Z5 catalyst, indicating that the core-shell structure catalyst has good anti-carbon deposition effect.
[0070] At 600℃, TGA-DSC analysis was performed on the three catalysts after 30h of methane dry gas reforming reaction. Figure 4 As shown. Specifically, the Ni@Z5 catalyst exhibited an 11% weight loss range, indicating that carbon deposition occurred on the catalyst during the reaction; in contrast, the weight loss of the Mo / Ni@Z5 catalyst was 9%, indicating that the addition of molybdenum helped to reduce carbon deposits generated by some reactions; it is worth noting that the Ni@Mo-Z5 catalyst did not show a weight loss range, but a small weight gain range was observed, which was mainly due to the oxidation of metallic Ni. This finding further confirms that when molybdenum is integrated into the molecular sieve framework, it can achieve high dispersion while avoiding agglomeration at high temperatures, thereby maintaining efficient carbon deposit elimination capabilities during the reaction.
[0071] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.
Claims
1. A nickel-based catalyst, characterized in that The catalyst comprises a base core and an auxiliary agent loaded on the base core, the base core comprises a porous carrier and a nickel precursor loaded in the pores of the porous carrier, the auxiliary agent comprises a molybdenum salt, the porous carrier comprises a Z5 molecular sieve, and the nickel precursor comprises a nickel salt and a chelating agent.
2. The catalyst according to claim 1, characterized in that The Z5 molecular sieve includes a structure directing agent, a silicon source and an aluminum source; the nickel salt includes at least one of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate; the chelating agent is ethylenediamine; the molybdenum salt includes at least one of sodium molybdate, ammonium molybdate and ammonium heptamolybdate; the nickel element in the nickel salt accounts for 1.0wt%-10.0wt% of the mass of the Z5 molecular sieve; the molybdenum element in the molybdenum salt accounts for 0.5wt%-5.0wt% of the mass of the Z5 molecular sieve.
3. The catalyst according to claim 2, characterized in that The structure directing agent includes TPAOH; the silicon source is selected from tetraethyl orthosilicate; the aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sulfate and aluminum chloride; the molar ratio of the structure directing agent, the silicon source and the aluminum source is 1:(0.05-0.04):(0.05-0.04).
4. A method for preparing the catalyst according to any one of claims 1 to 3, characterized in that: The following steps are involved: The nickel precursor and Z5 molecular sieve are subjected to hydrothermal crystallization reaction to obtain the base core; The base core and the molybdenum salt are subjected to a hydrothermal crystallization reaction to obtain a catalyst precursor; the catalyst precursor is reduced to obtain a nickel-based catalyst.
5. The preparation method according to claim 4, characterized in that: The hydrothermal crystallization reaction of the nickel precursor and the Z5 molecular sieve includes: mixing the nickel precursor and the Z5 molecular sieve and stirring for 1h-2h, then pouring into a reaction kettle, and placing in an oven at 170°C-180°C for reaction for 2d-4d.
6. The preparation method according to claim 4, characterized in that: The hydrothermal crystallization reaction of the base core and the molybdenum salt includes: mixing the base core and the molybdenum salt and stirring for 5h-7h, then pouring into a reaction kettle, and placing in an oven at 60°C-120°C for reaction for 4d-6d.
7. The preparation method according to claim 4, characterized in that: After the nickel precursor and the Z5 molecular sieve undergo a hydrothermal crystallization reaction and the base core and the molybdenum salt undergo a hydrothermal crystallization reaction, the obtained base core and the catalyst precursor need to be washed, dried and calcined, including: washing the obtained base core and the catalyst precursor with pure water and ethanol for 3-5 times, placing them in an oven at 70°C-100°C to dry for 5h-7h and calcining them in a muffle furnace at 400°C-800°C for 2h-10h.
8. A catalyst according to any one of claims 1 to 3, or a catalyst prepared by the preparation method according to any one of claims 4 to 7, characterized in that: Application in methane dry gas reforming reaction.
9. The use according to claim 8, characterized in that: At 500℃-800℃, methane and carbon dioxide generate carbon monoxide and hydrogen under the action of catalyst.