A preformed methane reforming catalyst and a method for preparing the same

Abstract

The application discloses a preformed methane reforming catalyst and a preparation method thereof. The catalyst comprises a nickel-active alumina first functional component, a cerium oxide nanocluster second functional component and an alumina inert phase. The preparation method comprises preforming an inert phase pretreatment, hydrothermal treatment, calcination and reduction. The preformed inert phase after pretreatment is used as a carrier, which greatly improves the catalyst strength, pertinently weakens the metal-carrier interaction, avoids bed layer temperature drop and carbon deposition caused by local high strength reaction, and improves the operation stability. The first functional component with a layered structure and the second functional component rich in oxygen vacancies further improve the catalyst activity and stability, and the performance indicators are overall superior to those of the existing catalyst products. The preparation method is simple and easy to implement, has no special requirements on equipment, and is conducive to the popularization and application in the fields of methane steam reforming and methane dry reforming.

Description

Technical Field

[0001] This invention relates to the field of energy and chemical engineering, specifically to a preformed methane reforming catalyst and its preparation method. Background Technology

[0002] The methane reforming process mainly refers to the reaction of methane with water and / or carbon dioxide under high temperature and high pressure conditions to produce hydrogen and carbon monoxide (syngas). When industrial waste carbon dioxide is introduced as a raw material, it can be converted into valuable syngas, which can then be used to synthesize high-value chemicals, achieving efficient utilization of carbon dioxide and demonstrating broad application prospects.

[0003] For a long time, catalysts have been a major technical bottleneck restricting the widespread application of methane reforming technology, especially methane-carbon dioxide reforming technology. On the one hand, because catalysts need to be exposed to high temperature (~800℃) and high pressure (~2MPa) environments for extended periods, and catalyst bed heights often exceed 10m, the requirements for catalyst strength are extremely high. On the other hand, catalysts are highly susceptible to deactivation due to active nickel agglomeration and sintering, reaction coking, and other factors, leading to decreased operational stability. Therefore, it is necessary to optimize the catalyst microstructure and strictly control the interactions between the metal, oxide, and support. Currently, there are very limited technical solutions that can simultaneously address these issues.

[0004] Invention patent CN115475620A discloses a method for preparing a methane multiple reforming catalyst and its application. It uses a pre-formed support prepared by high-temperature calcination of magnesium nitrate, calcium nitrate, α-alumina, boehmite, calcium oxide, polyethylene glycol, and guar gum powder, which is then impregnated with nickel nitrate and magnesium nitrate. The catalyst strength has an average of 160 N / cm. Invention patent CN104084211B discloses a catalyst for producing syngas or hydrogen, its preparation method, and its application. It uses alumina, magnesium oxide, calcium oxide, zirconium oxide, periclase, spinel, perovskite, etc., as supports, impregnated with loaded nickel oxide, chromium oxide, and alkaline earth / rare earth oxides. The lateral compressive strength is >400 N / particle. Invention patent CN106799263B discloses a high-strength hierarchical porous catalyst for methane triple reforming and its preparation method. A support is prepared by calcining a mixture of magnesium oxide, γ-alumina, graphite powder, ammonium carbonate, calcium aluminate cement, and magnesium stearate. The catalyst product is then impregnated in a metal salt solution, and the lateral compressive strength after high-temperature calcination exceeds 1000 N / particle. Invention patent CN112717914B discloses a methane-carbon dioxide reforming catalyst, its preparation method, and its application. A magnesium-aluminum hydrotalcite-pyrochlore composite support is impregnated in a nickel salt solution, and then the impregnated catalyst composite support is calcined to optimize its anti-sintering and anti-carbon deposition properties. The catalyst strength has not been reported. Invention patent CN109718770B discloses a catalyst support and supported catalyst, their preparation method and application, as well as a method for methane co-reforming. It uses α-Al₂O₃, MgAl₂O₄, CaAl₂O₄, CaSiO₃, or aluminosilicate supports, impregnated with supported metals Ni and / or Co (preferably Ni). The catalyst strength has not been reported. Invention patent CN 115193460B discloses a method for preparing a cerium oxide-coated silicon carbide-supported metal element catalyst suitable for methane-carbon dioxide reforming processes. The metal element is in-situ doped onto SiC, or directly loaded onto the SiC surface, and then a CeO₂ layer is coated on the outer layer of the catalyst to form a core-shell structure, thereby enhancing the catalyst's stability.

[0005] In summary, although researchers have made some progress in the development of methane reforming catalysts in recent years, the main active components are often loaded onto the catalyst through simple impregnation or co-precipitation methods, which makes it difficult to control the microstructure of the active components. Furthermore, the catalyst is prone to agglomeration and deactivation as the reaction time increases, leaving considerable room for optimization. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a preformed methane reforming catalyst and its preparation method, which is used for the production of hydrogen or syngas through methane reforming (steam reforming, dry reforming, partial oxidative reforming, etc.). It has the advantages of high strength, high activity, and stable performance and structure.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention provides a preformed methane reforming catalyst, the catalyst comprising a first functional component, a second functional component, and an inert phase; wherein the first functional component is nickel-activated alumina (Ni / a-Al2O3), and the second functional component is cerium oxide nanoclusters (CeO2). x NC), wherein the inert phase is inert aluminum oxide (i-Al2O3).

[0009] In this invention, the catalyst, in the form of oxides of the metal elements contained therein, comprises the following components in the following mass percentages: NiO 15-30 wt.%, CeO2 1-15 wt.%, Al2O3(a-Al2O3+i-Al2O3) 60-82 wt.%, based on a total mass of 100 wt.% of the oxides of the metal elements contained in the catalyst.

[0010] In this invention, the first functional component is nickel-active alumina, wherein the Ni:Al molar ratio is between 4:1 and 10:1 and it has a micro-layered structure. To further improve the activity, modified metal elements, including but not limited to magnesium, zinc and calcium, may also be added.

[0011] In this invention, the second functional component, cerium oxide nanoclusters, is CeO rich in oxygen vacancies. x Nanoclusters, with x ranging from 0.8 to 1.5.

[0012] In this invention, the inert alumina in the inert phase is pretreated α-phase alumina, and is pre-formed into cylindrical, annular, clover-shaped, porous cylindrical flower plate-shaped particles, etc., with a strength of not less than 500N / particle, and has a porous structure.

[0013] The catalyst of this invention enables the reforming reaction of methane with water vapor / carbon dioxide through a metal-metal oxide interface formed by the first and second functional components. In addition, the layered structure in the first functional component can prevent the agglomeration and sintering of active nickel, while the second functional component provides sufficient carbon dioxide adsorption activation sites and coking elimination sites. The inert phase, as a high-strength porous support, helps to disperse the first and second functional components and weakens the interaction between the metal and the support, thereby avoiding the problem of catalyst coking and pulverization caused by high-intensity reactions. This achieves the technical goals of maintaining catalyst strength, ensuring catalytic activity, and improving performance and structural stability.

[0014] Secondly, the present invention provides a method for preparing a preformed methane reforming catalyst, comprising the following steps: according to a proportion,

[0015] S101: Pre-treated pre-formed α-phase alumina particles (inert phase) are mixed evenly with a multi-metal salt aqueous solution;

[0016] S102: Add urea to the product of S101 and mix thoroughly;

[0017] S103: Transfer the mixed solution in S102 to a high-pressure reactor for hydrothermal reaction, then cool and hold at that temperature;

[0018] S104: Separate, wash, dry, calcinate to obtain the oxidized catalyst;

[0019] S105: Reduction, to obtain a reduced catalyst.

[0020] The preprocessing described in step S101 of this invention includes the following steps:

[0021] S201: Take pre-formed α-phase alumina particles and calcine them at 300-500℃ for 2-4 hours;

[0022] S202: Pour an alkaline solution with a pH of 10 to 14 into the calcined alumina particles at a solid-liquid mass ratio of 1:8 to 1:20, and stir at 15 to 35°C for 4 to 12 hours.

[0023] S203: Separate, wash until the pH of the washing solution is 6.5-8, dry, and calcine at 450-600℃ for 2-8 hours.

[0024] In S202 of the present invention, the alkali includes, but is not limited to, sodium hydroxide, potassium hydroxide, etc.

[0025] The metal components of the multi-metal salt aqueous solution of the present invention include nickel, aluminum and cerium, and may also include the modified metal elements described in the first functional component, including but not limited to magnesium, zinc and calcium.

[0026] As a preferred embodiment, in step S101 of the present invention, the mixing method includes stirring and ultrasound. The stirring temperature in step S101 is 15–60°C, the stirring time is 0.5–4 h, and the ultrasound treatment time is 5–30 min.

[0027] In step S102 of the present invention, the nickel:urea molar ratio is 1:1.2 to 1:3.5.

[0028] As a preferred embodiment, the temperature of step S102 in this invention is 15–40°C.

[0029] In step S103 of the present invention, the hydrothermal reaction temperature is 140-200℃ and the reaction time is 12-48h; the cooling endpoint temperature is 40-80℃ and the holding time is 8-12h.

[0030] The calcination temperature in step S104 of the present invention is 450-650°C.

[0031] The reduction in step S105 of this invention includes the following steps:

[0032] S301: Introduce reducing gas into the oxidized catalyst, control the concentration and pressure of the reducing gas, raise the temperature to the first target temperature and keep it constant to carry out the first stage of reduction;

[0033] S302: After heating to the second target temperature, gradually increase the concentration of reducing gas and maintain the temperature to carry out the second stage of reduction;

[0034] S303: Purge with inert gas and gradually reduce the reducing gas.

[0035] The reducing gas in step S301 of the present invention includes, but is not limited to, hydrogen, carbon monoxide, etc., and the concentration of the reducing gas is 10-30 vol% and the pressure is 0.5-2.5 MPa.

[0036] In step S301 of the present invention, the first target temperature is 350-450°C, and the heating rate is 5-8°C / min.

[0037] In step S301 of the present invention, the criterion for determining the end of the first stage of reduction is that the difference in the flow rate of the inlet and outlet reducing gas is ≤5%.

[0038] In step S302 of the present invention, the second target temperature is 550-800℃, and the heating rate is 5-8℃ / min.

[0039] In step S302 of this invention, the gradient of the reduction gas concentration is ≤10%, and the final concentration is ≥70%.

[0040] The criterion for determining the end of the second stage of reduction in step S302 of the present invention is that the difference in the flow rate of the inlet and outlet reducing gas is ≤5%.

[0041] The reduction gradient of the reducing gas concentration in step S303 of the present invention is ≤10%.

[0042] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0043] This invention provides a pre-formed methane reforming catalyst. Using a pre-treated pre-formed inert phase as a support, it not only effectively improves catalyst strength but also significantly reduces the impact of the forming process on the catalyst's active components, thereby greatly reducing the forming difficulty. The introduction of a first functional component with a micro-layered structure and a second functional component rich in oxygen vacancies ensures good dispersion of active nickel while promoting the adsorption and activation of carbon dioxide molecules, thus improving catalyst activity and stability. The use of an inert phase support specifically weakens the metal-support interaction, avoiding catalyst bed cooling and carbon buildup caused by localized high-intensity reactions, thus improving operational stability. The preparation method proposed in this invention is simple and easy to implement, requires no special equipment, and is conducive to its widespread application in methane steam reforming, methane dry reforming, and other fields.

[0044] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the following embodiments of the invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Unless otherwise specified, all pressures mentioned in this invention are absolute pressures. Detailed Implementation

[0045] The described embodiments are only a part of the embodiments in this specification, and not all of them. All other embodiments obtained by those skilled in the art based on one or more embodiments of this specification without inventive effort should fall within the protection scope of this document.

[0046] It should be noted that the embodiments of the present invention are described only to more clearly illustrate the technical solutions of the embodiments of the present invention, and do not constitute a limitation on the technical solutions provided by the embodiments of the present invention.

[0047] The main raw material sources in the embodiments and comparative examples of this invention are as follows; unless otherwise specified, all other raw materials were obtained through ordinary commercial channels:

[0048] Nickel nitrate: Sinopharm Group, purity 99%;

[0049] Cerium nitrate: Sinopharm Group, purity 99%;

[0050] Aluminum nitrate: Sinopharm Group, purity 99%;

[0051] Zinc nitrate: Sinopharm Group, purity 99%;

[0052] Magnesium nitrate: Sinopharm Group, purity 99%;

[0053] Urea: Sinopharm Group, purity 99%;

[0054] α-phase alumina particles: Chalco Shandong New Materials Co., Ltd., alumina content ≥97%.

[0055] Example 1:

[0056] The pretreatment steps for pre-formed α-phase alumina particles (inert phase) are as follows:

[0057] Take 1 kg of pre-formed α-phase alumina particles and place them in a muffle furnace. Calcinate them at 450℃ in air for 4 hours. After cooling to room temperature, immerse them in a 1 L sodium hydroxide solution with a pH of 14. Stir continuously at room temperature for 8 hours and then remove them. Rinse them 5 times with deionized water. The pH of the washing solution is measured to be 7. Stop rinsing and dry the particles in an oven at 110℃ for 12 hours. Place the dried particles in a muffle furnace and calcine them at 550℃ in air for 4 hours. After cooling to room temperature, recover them to complete the pretreatment.

[0058] Example 2:

[0059] The preparation of oxidized catalysts involves the following steps:

[0060] A mixed salt solution with a total concentration of 0.5 mol / L was prepared by mixing nickel nitrate, cerium nitrate, and aluminum nitrate in a molar ratio of Ni:Ce:Al = 8:1.9:0.1. Then, 130 g of pre-treated pre-formed α-phase alumina particles were added, and the mixture was stirred at 30 °C for 4 h and ultrasonically treated for 15 min. Under stirring conditions, 1 mol of urea powder was added to the solution, which was then sealed with a sealing film and stirred at 30 °C for 1 h. The solution and particles were transferred to a high-pressure reactor and hydrothermally reacted at 160 °C for 24 h. After the hydrothermal reaction, the temperature was lowered to 80 °C at a rate of 10 °C / min and held for 12 h. After the reactor cooled to room temperature, it was opened, the insoluble matter was filtered out, washed five times with deionized water, and dried in an oven at 110 °C for 12 h. The dried insoluble matter was placed in a muffle furnace and calcined at 550 °C in air for 4 h. After cooling to room temperature, it was recovered to obtain oxidized catalyst 1.

[0061] Catalyst 1, in the form of oxides of the metal elements it contains, has the following mass percentages: NiO2 4.6%, CeO2 14.1%, and Al2O3 61.3%.

[0062] Example 3:

[0063] The preparation of oxidized catalysts involves the following steps:

[0064] A mixed salt solution with a total concentration of 0.5 mol / L was prepared by mixing nickel nitrate, cerium nitrate, and aluminum nitrate in a molar ratio of Ni:Ce:Al = 8:0.5:1.5. 130 g of pre-treated pre-formed α-phase alumina particles were then added, and the mixture was stirred at 20°C for 3 h and ultrasonically treated for 30 min. Under stirring conditions, 1.2 mol of urea powder was added to the solution, which was then sealed with a sealing film and stirred at 20°C for 1 h. The solution, along with the particles, was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 12 h. After the hydrothermal reaction, the temperature was lowered to 60°C at a rate of 10°C / min and held for 8 h. After the reactor cooled to room temperature, it was opened, the insoluble matter was filtered out, washed five times with deionized water, and dried in an oven at 110°C for 12 h. The dried insoluble matter was placed in a muffle furnace and calcined at 600°C in air for 2 h. After cooling to room temperature, it was recovered to obtain oxidized catalyst 2.

[0065] Catalyst 2, in the form of oxides of the metal elements it contains, has the following mass percentages: NiO2 4.2%, CeO2 1.9%, and Al2O3 73.9%.

[0066] Example 4:

[0067] The preparation of oxidized catalysts involves the following steps:

[0068] A 1L mixed salt solution with a total concentration of 0.5mol / L was prepared by mixing nickel nitrate, cerium nitrate, and aluminum nitrate in a molar ratio of Ni:Ce:Al = 8:1:1. 200g of pre-treated pre-formed α-phase alumina particles were then added, and the mixture was stirred at 60℃ for 4h and ultrasonically treated for 30min. Under stirring conditions, 0.5mol of urea powder was added to the solution, which was then sealed with a sealing film and stirred at 40℃ for 1h. The solution, along with the particles, was transferred to a high-pressure reactor and hydrothermally reacted at 140℃ for 48h. After the hydrothermal reaction, the temperature was lowered to 40℃ at a rate of 10℃ / min and held for 12h. After the reactor cooled to room temperature, it was opened, the insoluble matter was filtered out, washed five times with deionized water, and dried in an oven at 110℃ for 12h. The dried insoluble matter was placed in a muffle furnace and calcined at 500℃ in air for 4h. After cooling to room temperature, it was recovered to obtain the oxidized catalyst 3.

[0069] Catalyst 3, in the form of oxides of the metal elements it contains, has the following mass percentages: NiO 16.2%, CeO2 4.6%, and Al2O3 79.2%.

[0070] Example 5:

[0071] The preparation of oxidized catalysts involves the following steps:

[0072] Prepare a 1 L mixed salt solution with a total concentration of 0.5 mol / L by mixing nickel nitrate, cerium nitrate, aluminum nitrate, and magnesium nitrate in a molar ratio of Ni:Ce:Al:Mg = 8:1:0.1:0.9. Then add 160 g of pre-treated α-phase alumina particles, stir at 30 °C for 4 h, and sonicate for 15 min. Under stirring conditions, add 1 mol of urea powder to the solution, seal with sealing film, and stir at 30 °C for 1 h. Combine the above solution with the prepared α-phase alumina particles. The particles were transferred to a high-pressure reactor and hydrothermally reacted at 160℃ for 24 hours. After the hydrothermal reaction, the temperature was lowered to 80℃ at a rate of 10℃ / min and held for 12 hours. After the reactor cooled to room temperature, the reactor was opened, the insoluble matter was filtered out and washed 5 times with deionized water, and then dried in an oven at 110℃ for 12 hours. The dried insoluble matter was placed in a muffle furnace and calcined at 550℃ in air atmosphere for 4 hours. After cooling to room temperature, it was recovered to obtain the oxidized catalyst 4.

[0073] Catalyst 4, in the form of oxides of the metal elements it contains, has the following mass percentages: NiO2 0.3%, CeO2 5.8%, Al2O3 72.8%, and MgO 1.1%.

[0074] Example 6:

[0075] The preparation of oxidized catalysts involves the following steps:

[0076] Prepare a 1 L mixed salt solution with a total concentration of 0.5 mol / L by mixing nickel nitrate, cerium nitrate, aluminum nitrate, and zinc nitrate in a molar ratio of Ni:Ce:Al:Zn = 8:1:0.1:0.9. Then add 160 g of pre-treated α-phase alumina particles, stir at 30 °C for 4 h, and sonicate for 15 min. Under stirring conditions, add 1 mol of urea powder to the solution, seal with sealing film, and stir at 30 °C for 1 h. Combine the above solution with the prepared α-phase alumina particles. The particles were transferred to a high-pressure reactor and hydrothermally reacted at 160℃ for 24 hours. After the hydrothermal reaction, the temperature was lowered to 80℃ at a rate of 10℃ / min and held for 12 hours. After the reactor cooled to room temperature, the reactor was opened, the insoluble matter was filtered out and washed 5 times with deionized water, and then dried in an oven at 110℃ for 12 hours. The dried insoluble matter was placed in a muffle furnace and calcined at 550℃ in air atmosphere for 4 hours. After cooling to room temperature, it was recovered to obtain the oxidized catalyst 5.

[0077] Catalyst 5, in the form of oxides of the metal elements it contains, has the following mass percentages: NiO 18.9%, CeO2 5.1%, Al2O3 75.2%, and ZnO 0.8%.

[0078] Example 7:

[0079] The preparation of the reduced catalyst involves the following steps:

[0080] Take 15g of catalyst 1 prepared in Example 2 and load it into a fixed-bed reactor. Purge with nitrogen at 1MPa and room temperature for 1h. The oxygen content at the outlet was detected by online gas chromatograph and found to be 0.01%, which met the reduction conditions. Introduce 20% hydrogen into the reactor and slowly heat it from room temperature to 400℃ at a heating rate of 5℃ / min. After holding at this temperature for 2h, the difference in hydrogen flow rate between the inlet and outlet was measured to be 0.2%. Then heat it to 600℃ at a heating rate of 5℃ / min and hold it at this temperature for 30min. Subsequently, gradually increase the hydrogen concentration to 100% in a 10% concentration gradient. After holding at this temperature for 3.5h, the difference in hydrogen flow rate between the inlet and outlet was measured to be 0.04%. Continue purging with nitrogen and decrease the hydrogen concentration in a 10% concentration gradient until it is zero. Then, cool the reactor temperature to 60℃ at a cooling rate of 10 / min and stop introducing nitrogen. The preparation of the reduced catalyst is now complete. After the reactor temperature has naturally cooled to room temperature, remove the catalyst to obtain reduced catalyst 1.

[0081] The preparation process of reduced catalysts 2-5 is as described in Example 7. Unless otherwise specified, all catalysts described in this invention are in the oxidized state.

[0082] Comparative Example 1:

[0083] A commercial methane steam reforming catalyst (Southwest Institute Z111 series SMR catalyst) was used as the control catalyst 1.

[0084] Comparative Example 2:

[0085] The catalyst is prepared by an equal-volume impregnation method, and the steps are as follows:

[0086] A mixed salt solution with a total concentration of 5 mol / L was prepared by mixing nickel nitrate, cerium nitrate, and aluminum nitrate in a molar ratio of Ni:Ce:Al = 8:1.9:0.1. This solution was then added dropwise to 130 g of pre-treated pre-formed α-phase alumina particles and dried in an oven at 110 °C for 12 h. The dried insoluble material was then placed in a muffle furnace and calcined at 650 °C in air for 4 h. After cooling to room temperature, the material was recovered to obtain the oxidized comparative catalyst 2.

[0087] Compared with catalyst 2, the mass percentages of each component, in the form of oxides of the metal elements contained therein, are 5.3% NiO2, 14.6% CeO2, and 60.1% Al2O3.

[0088] Comparative Example 3:

[0089] The preparation of catalysts without inert phase supports involves the following steps:

[0090] A 1 L mixed salt solution with a total concentration of 0.5 mol / L was prepared by mixing nickel nitrate, cerium nitrate, and aluminum nitrate in a molar ratio of Ni:Ce:Al = 8:1.9:0.1. The solution was stirred at 30 °C for 4 h and then sonicated for 15 min. Under stirring conditions, 1 mol of urea powder was added to the solution, sealed with a sealing film, and stirred at 30 °C for 1 h. The solution, along with the particles, was transferred to a high-pressure reactor and hydrothermally reacted at 160 °C for 24 h. After the hydrothermal reaction, the temperature was lowered to 80 °C at a rate of 10 °C / min and held for 12 h. After the reactor cooled to room temperature, it was opened, the insoluble matter was filtered out, washed 5 times with deionized water, and dried in an oven at 110 °C for 12 h. The dried insoluble matter was placed in a muffle furnace and calcined at 550 °C in air atmosphere for 4 h. After cooling to room temperature, it was recovered to obtain the oxidized comparative catalyst 3.

[0091] Compared with catalyst 3, the mass percentage of each component, in the form of oxides of the metal elements contained therein, is 74.8% NiO, 19.6% CeO2, and 5.6% Al2O3.

[0092] Comparative Example 4:

[0093] The preparation of activated alumina-supported catalysts involves the following steps:

[0094] A mixed salt solution with a total concentration of 0.5 mol / L was prepared by mixing nickel nitrate, cerium nitrate, and aluminum nitrate in a molar ratio of Ni:Ce:Al = 8:1.9:0.1. 130 g of activated alumina particles (γ phase) were then added, and the mixture was stirred at 30 °C for 4 h and ultrasonically treated for 15 min. While stirring, 1 mol of urea powder was added to the solution, which was then sealed with a sealing film and stirred at 30 °C for 1 h. The solution, along with the particles, was transferred to a high-pressure reactor and hydrothermally reacted at 160 °C for 24 h. After the hydrothermal reaction, the temperature was lowered to 80 °C at a rate of 10 °C / min and held for 12 h. After the reactor cooled to room temperature, it was opened, the insoluble matter was filtered out, washed five times with deionized water, and dried in an oven at 110 °C for 12 h. The dried insoluble matter was placed in a muffle furnace and calcined at 550 °C in air for 4 h. After cooling to room temperature, it was recovered to obtain the oxidized comparative catalyst 4.

[0095] Compared with catalyst 4, the mass percentages of each component, in the form of oxides of the metal elements contained therein, are 7.2% NiO2, 12.9% CeO2, and 59.9% Al2O3.

[0096] Comparative Example 5:

[0097] Following the preparation method of catalyst 1, the only difference is that no nickel salt is added during the preparation process, while other operations and conditions remain unchanged, resulting in comparative catalyst 5. The mass percentages of each component, calculated in the form of oxides of the metal elements contained therein, are 8.2% CeO2 and 91.8% Al2O3.

[0098] Comparative Example 6:

[0099] Following the preparation method of catalyst 1, the only difference is that no cerium salt is added during the preparation process, while other operations and conditions remain unchanged, resulting in comparative catalyst 6. The mass percentages of each component, calculated in the form of oxides of the metal elements contained therein, are: NiO 24.0% and Al2O3 76.0%.

[0100] Comparative Example 7:

[0101] Following the preparation method of catalyst 1, the only difference is that no aluminum salt is added during the preparation process, while other operations and conditions remain unchanged, resulting in comparative catalyst 7. The mass percentages of each component, calculated in the form of oxides of the metal elements contained therein, are: NiO 24.4%, CeO2 12.6%, and Al2O3 63.0%.

[0102] Catalyst characterization and analysis:

[0103] Catalysts 1-5 and comparative catalysts 1-7 prepared in Examples 2-6 and Comparative Examples 1-7 were characterized and analyzed, and the results are shown in Table 1.

[0104] The performance test parameters used in all embodiments of the present invention were obtained using conventional standard methods:

[0105] Nickel content: Inductively coupled plasma (ICP) spectroscopy, in the form of NiO;

[0106] BET specific surface area: low-temperature nitrogen adsorption-desorption isotherm (calculated using the BET model);

[0107] Lateral compressive strength: Digital display particle strength tester;

[0108] Main crystalline phase: X-ray diffraction (XRD).

[0109] Table 1. Characterization results of catalysts prepared in the examples and comparative examples.

[0110]

[0111] As can be seen from the data in Table 1 above, the nickel content of the catalyst prepared by this invention is very close to the feed amount, and the nickel content is effectively controlled within the range of 15% to 30%, and the preparation effect is consistent with expectations.

[0112] The catalyst prepared by this invention has an average BET specific surface area that is 3.1 times that of the comparative catalyst 1, providing an ideal contact surface for the raw materials and catalyst active sites, which is beneficial to the mass transfer process of raw materials and products, thereby improving the reaction performance.

[0113] The catalyst prepared by this invention contains a layered polymetallic oxide and α-Al2O3 crystal structure, exhibiting a multi-component composite crystal phase. In contrast, the crystal structures of the commonly used comparative catalysts 1 and 2 in this field are relatively simple, and the technical solution of this invention has obvious advantages.

[0114] The catalyst prepared by this invention has a side compressive strength of approximately 607 N / cm, which is higher than that of comparative catalysts 1 and 3, demonstrating its high strength characteristics and making it easier to maintain morphological stability under high temperature and high pressure reaction conditions.

[0115] Comparative Examples 3, 4, 5, 6, and 7 show that using activated alumina as a carrier or removing any one of the components nickel, cerium, or aluminum cannot form the catalyst product described in this invention.

[0116] Catalyst reaction performance test:

[0117] The catalytic performance of catalysts 1-5 and comparative catalysts 1-7 prepared in Examples 2-6 and Comparative Examples 1-7 was tested using a high-pressure fixed-bed reactor. Before testing, all catalysts were reduced to a reduced state using the method described in Example 7. The tested reaction was the methane reforming to syngas reaction, using a Φ5×5mm cylindrical catalyst. The reactants were methane, water vapor, and / or carbon dioxide. The reaction temperature was 800℃, and the space velocity was 12000 h⁻¹. -1 The results are shown in Table 2.

[0118] Table 2. Results of reaction performance tests on catalysts prepared in the examples and comparative examples (all catalysts were in reduced state).

[0119]

[0120]

[0121] As shown in Table 2 above, regardless of whether it is methane steam reforming (H2O:CO2:CH4 = 3:0:1), methane dry reforming (H2O:CO2:CH4 = 0:1:1), or methane combined reforming (H2O:CO2:CH4 = 1.5:1:1), the catalyst prepared in this invention exhibits the highest methane conversion rate, the best performance stability, and the lowest amount of reaction coke, and the catalyst morphology is well maintained, thus demonstrating the best performance.

Claims

1. A preformed methane reforming catalyst, said catalyst comprising a first functional component, nickel-activated alumina (Ni / a-Al2O3), and a second functional component, cerium oxide nanoclusters (CeO). x The catalyst comprises NC and inert phase inert alumina i-Al2O3; a pre-treated inert phase as a support; a first functional component with a micro-layered structure and a second functional component rich in oxygen vacancies; the nickel-activated alumina having a Ni:Al molar ratio of 4:1 to 10:1; x of 0.8 to 1.5 in the cerium oxide nanoclusters; and the catalyst comprising, in the form of oxides of the metal elements contained therein, the following components by mass percentage: NiO 15 to 30 wt.%, CeO2 1 to 15 wt.%, α-Al2O3 + i-Al2O3 60 to 82 wt.%, based on a total mass of 100 wt.% of the metal elements contained in the catalyst in the form of oxides.

2. A process for the preparation of the catalyst of claim 1 comprising the steps of: Proportionally, S101: uniformly mixing pre-formed α-phase alumina particles after pretreatment with an aqueous solution of a multi-metal salt; S102: adding urea to the product of S101 and uniformly mixing; S103: transferring the mixed solution in S102 to a high-pressure reaction kettle for hydrothermal reaction, then cooling and keeping temperature; S104： separating, washing, drying, and calcining to obtain an oxidation state catalyst; S105: reduction to obtain a reduced state catalyst; The metal components of the aqueous solution of the multi-metal salt include nickel, aluminum, and cerium.

3. The method of claim 2, wherein, The pretreatment in S101 includes the following steps: S201: taking pre-formed α-phase alumina particles, calcining them at 300-500°C for 2-4h; S202: pouring an alkaline solution with a pH value of 10-14 into the calcined alumina particles at a solid-liquid mass ratio of 1:8-1:20, stirring at 15-35°C for 4-12h; S203: separating, washing until the pH value of the washing liquid is 6.5-8, drying, and calcining at 450-600°C for 2-8h.

4. The method of claim 2, wherein, The reduction in S105 includes the following steps: S301: introducing a reducing gas into the oxidation state catalyst, controlling the concentration and pressure of the reducing gas, heating to a first target temperature and keeping temperature constant, and performing first-stage reduction; S302: after heating to a second target temperature, gradually increasing the concentration of the reducing gas and keeping temperature constant, and performing second-stage reduction; S303: inert gas purging and gradually reducing the reducing gas.

5. The method of claim 2, wherein, In S101, the mixing method includes stirring and ultrasonic treatment; wherein the stirring temperature is 15-60°C, the stirring time is 0.5-4h, and the ultrasonic treatment time is 5-30min.

6. The method of claim 2, wherein, In S102, the molar ratio of nickel to urea is 1:1.2-1:3.5; the temperature in S102 is 15-40°C; the hydrothermal reaction temperature in S103 is 140-200°C, the reaction time is 12-48h; the final cooling temperature is 40-80°C, and the holding time is 8-12h; the calcination temperature in S104 is 450-650°C.

7. The method of claim 4, wherein, In S301, the first target temperature is 350-450°C, and the heating rate is 5-8°C / min; in S302, the second target temperature is 550-800°C, and the heating rate is 5-8°C / min.

8. The method of claim 2, wherein, The metal components of the aqueous solution of the multi-metal salt also contain one or more of magnesium, zinc, and calcium.

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