A catalyst for efficient and stable hydrogen release of cyclohexane, a preparation method and application thereof

Abstract

This invention belongs to the field of organic hydrogen storage, specifically relating to a catalyst for the efficient and stable release of hydrogen from cyclohexane, its preparation method, and its application. The catalyst comprises an active component, an additive, and a support. The active component is a noble metal element from Group VIII, the additive is a transition metal element, and the support is γ-Al₂O₃. This invention, through the organic combination of support design and a bimetallic synergistic strategy, improves catalytic activity, selectivity, stability, and anti-carbon deposition performance while reducing the amount of noble metal used, providing an innovative solution for developing efficient, stable, and economical industrial dehydrogenation catalysts.

Description

Technical Field

[0001] This invention belongs to the field of organic hydrogen storage, specifically relating to a catalyst for the efficient and stable release of hydrogen from cyclohexane, its preparation method, and its application. Background Technology

[0002] With the increasing global population and continuous development of the global economy, the demand for energy is growing. Traditional fossil fuels such as coal, oil, and natural gas are facing depletion, and the greenhouse gases released from their combustion are exacerbating global climate change. Therefore, there is an urgent need to develop clean, efficient, and sustainable new energy sources. Hydrogen energy is an ideal clean energy source with advantages such as being pollution-free, having a high calorific value, and being widely available, showing great potential for future applications. Currently, there are still many problems in the application of hydrogen energy, especially regarding hydrogen storage and transportation. The quality of hydrogen storage technology directly affects the efficiency, cost, and safety of hydrogen use. At present, hydrogen storage technologies mainly include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, solid-state hydrogen storage, and organic liquid hydrogen storage, among which organic liquid hydrogen storage technology has attracted much attention due to its high hydrogen storage density, good safety, low storage and transportation costs, and recyclability. Organic liquid hydrogen storage technology achieves the absorption and release of hydrogen through the reversible reaction between liquid organic matter and hydrogen. However, current organic liquid phase hydrogen storage technologies suffer from problems such as poor stability and numerous side reactions. The hydrogenation step in organic liquid hydrogen storage processes has mature industrial applications, while research on dehydrogenation reactions is relatively limited. The key to dehydrogenation reactions is the catalyst; therefore, developing a dehydrogenation catalyst with high stability, high selectivity, and high conversion rate is crucial for hydrogen energy applications. Among many cycloalkanes, cyclohexane is a better hydrogen storage material in the field of organic liquid-phase hydrogen storage due to its high hydrogen storage density (7.19 wt%) and more mature industrial applications.

[0003] Noble metal dehydrogenation catalysts are widely used in the dehydrogenation of organic liquids due to their high activity and selectivity at low temperatures. However, current dehydrogenation catalysts suffer from low activity and stability, which hinders their industrial application. To address this issue, methods such as support modification, active component optimization, and improved loading techniques are commonly employed and have already been applied in dehydrogenation catalysts.

[0004] CN111889096A proposes a composite support for alumina modified with Ti or Zr oxides. The surface of the support is uniformly modified using vapor deposition for loading noble metal catalysts. By adjusting the Ti / Zr oxide ratio, the Pt loading is reduced to 0.1-0.7 wt.%, while non-noble metals are introduced as synergistic active components to enhance dehydrogenation activity. However, the alumina-based support in this method still contains some acidic sites, which may lead to side reactions during dehydrogenation and affect the selectivity of the reaction.

[0005] CN111725531A uses Ce-Mg-Al or Zr-Mg-Al hydrotalcite as a support and is synthesized via a co-precipitation method. Utilizing the layered structure and alkaline properties of hydrotalcite, it effectively neutralizes the acidity of the support, reducing side reactions. Furthermore, the introduction of Ce or Zr into the hydrotalcite promotes electron transfer in the active components, enhancing dehydrogenation activity. However, the hydrotalcite support is prone to layered structure collapse at high temperatures (>400℃), leading to agglomeration of active metal particles and affecting catalyst lifetime. Additionally, this catalyst requires loading 0.5-10 wt.% of precious metals, resulting in high catalyst cost.

[0006] CN113976114A employs a pentafluoroaniline (PFA) aqueous solution to modify the surface of activated carbon. Through chemical adsorption and thermal treatment, a stable hydrophobic-oleophilic interface is formed, inhibiting carbon deposition and improving anti-coking performance. Simultaneously, the activated carbon is pretreated under a high-temperature inert atmosphere to remove surface oxygen-containing groups, reduce acidity, and minimize side reactions. However, the catalyst preparation process uses the toxic reagent PFA, and the modification and stepwise reduction processes are cumbersome, making industrial scale-up difficult and environmentally costly.

[0007] CN113070061A employs a method of introducing rare earth elements such as Ce, La, and Y into an Al₂O₃ support to form a composite oxide support via co-precipitation. This alters the electronic properties of the support and enhances the interaction between the active component and the support. Furthermore, stepwise impregnation and hydrogen reduction activation in a rotating tube furnace are used to achieve a high degree of dispersion of noble metal single-atom forms. However, single-atom catalysts are prone to noble metal atom migration and aggregation at high temperatures, exhibiting poor stability. Moreover, the preparation of single-atom catalysts is challenging, hindering industrial scale-up.

[0008] To address the problems identified in the aforementioned studies, this invention utilizes Al2O3 derived from Al-based metal-organic frameworks (Al-MOFs) as a support. By stepwise loading of bimetallic promoters and active components, an Al-MOF dehydrogenation catalyst is obtained for the dehydrogenation reaction of cyclohexane. MOF materials possess a stable microstructure, and their derived oxides exhibit stable pore structures, which facilitates the stable distribution of active components on the support and inhibits the aggregation of noble metals. The loaded bimetallic promoters weaken product adsorption through electronic regulation, stabilize the active structure to inhibit sintering, and synergistically remove carbon deposits through oxygen storage capacity, thereby improving the conversion rate of the dehydrogenation catalyst and enabling long-term stable operation. The controllable pore structure of MOFs, with its microporous structure, promotes the uniform dispersion of noble metal elements, exposes more active sites, and reduces the amount of noble metals used in the preparation process. The preparation process of MOFs is relatively simple, contains no highly toxic substances, reduces environmental problems associated with catalyst preparation, and lowers the cost of industrial scale-up.

[0009] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventors studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0010] This invention belongs to the field of organic hydrogen storage, specifically relating to a catalyst for the efficient and stable release of hydrogen from cyclohexane, its preparation method, and its application.

[0011] To address the aforementioned technical problems, one objective of this invention is to provide a method for preparing a catalyst for the efficient and stable release of hydrogen from cyclohexane, comprising the following steps: (1) Disperse soluble aluminum salt and organic ligand in deionized water, add acid solution, sonicate at 50~80℃ for 30~120 min, transfer to hydrothermal reactor and react at 150~260℃ for 16~72 h, cool to room temperature after reaction, filter, wash and dry to obtain Al-MOF; (2) Add the additive to deionized water to prepare salt solution A, prepare NaOH and Na2CO3 to prepare alkaline solution B, add the Al-MOF obtained in step (1) to salt solution A and disperse it evenly, stir evenly, then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 8.4~9.2, continue the reaction for 0.5~3 h, then pour the suspension after the reaction into a hydrothermal reactor, age it at 92~105℃ for 8~12 h, filter, wash and dry, then calcine the precipitate under an inert atmosphere to obtain the carrier; (3) Dilute the noble metal salt solution to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, perform gradient drying and calcination to obtain the dehydrogenation catalyst.

[0012] According to a preferred embodiment, the soluble aluminum salt is one of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0013] According to a preferred embodiment, the organic ligand is one or more of terephthalic acid, pyromellitic acid, dimethyl terephthalate, and tripyromellitic acid.

[0014] According to a preferred embodiment, the amount of acid solution added is 0 to 8 mL. The acid solution is, for example, nitric acid.

[0015] According to a preferred embodiment, the additive is a nitrate or tin chloride corresponding to magnesium (Mg), cerium (Ce), lanthanum (La), copper (Cu), iron (Fe), or cobalt (Co).

[0016] According to a preferred embodiment, the calcination temperature in step (2) is 300~600℃ for 3 h.

[0017] According to a preferred embodiment, the ratio of NaOH to Na2CO3 in alkaline solution B is 4~10:1.

[0018] According to a preferred embodiment, in step (3), the gradient drying temperature is 60°C, 70°C, 85°C, 100°C and 120°C, the calcination temperature is 300~500°C and the calcination time is 2~4 h.

[0019] According to a preferred embodiment, the precious metal salt solution is a nitrate or chloride solution corresponding to platinum (Pt), palladium (Pd), rhodium (Rh), or ruthenium (Ru). The precious metal content is 0.01~0.5 wt% by mass of the metal.

[0020] One of the objectives of this invention is to provide a catalyst for the efficient and stable release of hydrogen from cyclohexane, comprising an active component, an auxiliary agent, and a support, wherein the active component is a noble metal element from Group VIII, the auxiliary agent is a transition metal element, and the support is γ-Al2O3.

[0021] According to a preferred embodiment, the noble metal element in Group VIII is one or more of Pt, Pd, Rh, and Ru.

[0022] According to a preferred embodiment, the additive is a transition metal element. The additive is one of Mg / Ce, Mg / La, Sn / Cu, and Fe / Co. The additive content is 3~15 wt%.

[0023] According to a preferred embodiment, the specific surface area of ​​the catalyst is not less than 150 m². 2 / g.

[0024] γ-Al₂O₃ derived from Al-based metal-organic frameworks (Al-MOFs). The Al-based metal-organic frameworks are one of MIL-53-Al, MIL-69-Al, MIL-96-Al, MIL-100-Al, MIL-110-Al, and MIL-121-Al. The specific surface area of ​​Al-MOFs ranges from 500 to 1200 m². 2 / g, with a pore size of 0.5~2 nm. The specific surface area of ​​the derived γ-Al₂O₃ is 150~400 m² / g. 2 / g, with a pore size of 5~10 nm.

[0025] According to a preferred embodiment, the catalyst is prepared based on the preparation method described above.

[0026] One of the objectives of this invention is to provide the application of the above-mentioned catalyst for efficient and stable hydrogen release from cyclohexane in aromatic hydrocarbon production or hydrogen storage production.

[0027] One of the objectives of this invention is to provide the application of the above-mentioned catalyst for efficient and stable hydrogen release from cyclohexane in the evaluation of the cyclohexane dehydrogenation process. The evaluation conditions include: the mass of the catalyst being evaluated is 5-10 g; the heating temperature is set at 320-380℃; the reaction is carried out at atmospheric pressure; and the flow rate of cyclohexane is 0.1-0.8 mL / min.

[0028] The beneficial effects of this invention are: The technical solution involved in this invention utilizes Al-based metal-organic framework-derived γ-Al₂O₃ as a support. This support inherits the large specific surface area and specific morphology of MOF materials, providing an ideal substrate for the uniform dispersion and high loading of noble metals. This facilitates the formation of small, uniformly distributed noble metal nanoparticles, thereby exposing more active crystal faces and effectively increasing the density of active sites. Simultaneously, the ordered hierarchical pore structure formed by the MOF derivative significantly reduces the diffusion resistance of macromolecular reactants and products, thereby improving the mass transfer efficiency and overall performance of the dehydrogenation reaction. This structural advantage of the support allows for a significant reduction in the amount of noble metal used while achieving the same catalytic activity, resulting in substantial economic benefits.

[0029] Furthermore, the MOF-derived support possesses a stable framework structure, which helps suppress support sintering and pore structure collapse under high-temperature reaction conditions, thereby significantly improving the overall stability of the catalyst. More importantly, this invention achieves multiple synergistic optimizations of catalyst performance by loading a bimetallic promoter: the electronic interaction between the promoter metal and the noble metal can regulate the electronic state of the active sites, optimizing their adsorption and activation capabilities for reactants; the structural effect of the bimetallic system can further stabilize the noble metal nanoparticles, preventing their migration and aggregation; simultaneously, the introduction of the promoter effectively regulates the acidity and alkalinity of the catalyst surface, significantly inhibiting the occurrence of side reactions such as coking, thereby greatly enhancing the catalyst's resistance to coking and its long-term operational stability.

[0030] In summary, this invention, through the organic combination of support design and a bimetallic synergistic strategy, improves catalytic activity, selectivity, stability, and anti-carbon deposition performance while reducing the amount of precious metals used, providing an innovative solution for developing efficient, stable, and economical industrial dehydrogenation catalysts. Detailed Implementation

[0031] In the description of this invention, terminology is used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0032] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials, reagents or instruments used, unless otherwise specified by the manufacturer, are all commercially available reagents and materials; the conditions not specified in the examples are all carried out according to conventional conditions or conditions recommended by the manufacturer. At the same time, the present invention does not limit the source of the raw materials used. Unless otherwise specified, the raw materials used in the present invention are all commercially available products in this technical field.

[0033] The additives involved in this application, also known as co-catalysts or promoters, are auxiliary substances that do not have catalytic activity or have very low activity, but can significantly improve the performance of the main catalyst.

[0034] Example 1 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 7.33 g aluminum nitrate nonahydrate and 2.37 g terephthalic acid were dispersed in 30 mL of deionized water, and 3 mL of nitric acid solution (1 M) was added. After sonication at 60 °C for 120 min, the mixture was transferred to a hydrothermal reactor and reacted at 200 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 1.056 g magnesium nitrate hexahydrate and 5.667 g cerium nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B with NaOH and Na2CO3 in a mass ratio of 6:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 8.5. Continue the reaction for 1 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 95℃ for 9 h. After filtration, washing and drying, calcine the precipitate at 500℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the platinum nitrate solution containing 0.3 wt% Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 400℃ for 2 h to obtain dehydrogenation catalyst S1.

[0035] Example 2 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 15.87 g aluminum sulfate octadecylhydrate and 3.59 g trimethyl pyromellitic acid were dispersed in 30 mL of deionized water, 2 mL of nitric acid solution (1 M) was added, and the mixture was sonicated at 75 °C for 90 min. The mixture was then transferred to a hydrothermal reactor and reacted at 180 °C for 46 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 4.543 g magnesium nitrate hexahydrate and 5.757 g lanthanum nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B with NaOH and Na2CO3 in a mass ratio of 10:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 9. Continue the reaction for 2 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 92℃ for 8 h. After filtration, washing and drying, calcine the precipitate at 450℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the palladium nitrate solution containing 0.25 wt% Pd to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 350℃ for 2.5 h to obtain dehydrogenation catalyst S2.

[0036] Example 3 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 4.28 g aluminum nitrate nonahydrate and 1.26 g pyromellitic acid were dispersed in 30 mL of deionized water, and 4 mL of nitric acid solution (1 M) was added. After sonication at 80 °C for 70 min, the mixture was transferred to a hydrothermal reactor and reacted at 240 °C for 28 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 1.315 g of stannous chloride dihydrate and 5.026 g of copper nitrate trihydrate to deionized water to prepare salt solution A. Prepare alkaline solution B by mixing NaOH and Na2CO3 in a mass ratio of 8:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH of the solution is 8.6. Continue the reaction for 2.5 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 100℃ for 10 h. After filtration, washing and drying, calcine the precipitate at 350℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the platinum nitrate solution containing 0.15 wt% Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 370℃ for 3 h to obtain dehydrogenation catalyst S3.

[0037] Example 4 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 2.66 g aluminum chloride hexahydrate and 1.27 g trimethyl pyromellitic acid were dispersed in 30 mL of deionized water, 2 mL of nitric acid solution (1 M) was added, and the mixture was sonicated at 60 °C for 60 min. The mixture was then transferred to a hydrothermal reactor and reacted at 170 °C for 36 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 0.432 g magnesium nitrate hexahydrate and 4.063 g cerium nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B with NaOH and Na2CO3 in a mass ratio of 5:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 9. Continue the reaction for 0.5 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 98℃ for 9 h. After filtration, washing and drying, calcine the precipitate at 450℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the rhodium trichloride solution containing 0.4 wt% Rh to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 420℃ for 2 h to obtain dehydrogenation catalyst S4.

[0038] Example 5 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 3.37 g aluminum nitrate nonahydrate and 3.10 g pyromellitic acid were dispersed in 30 mL of deionized water, and 3 mL of nitric acid solution (1 M) was added. After sonication at 55 °C for 90 min, the mixture was transferred to a hydrothermal reactor and reacted at 240 °C for 50 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 12.939 g of ferric nitrate nonahydrate and 1.554 g of cobalt nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B with NaOH and Na2CO3 in a mass ratio of 4:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH of the solution is 8.8. Continue the reaction for 2 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 99℃ for 11 h. After filtration, washing and drying, calcine the precipitate at 550℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the palladium nitrate solution containing 0.35 wt% Pd to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 450℃ for 4 h to obtain dehydrogenation catalyst S5.

[0039] Example 6 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 2.86 g aluminum nitrate nonahydrate and 1.78 g trimethyl pyromellitic acid were dispersed in 30 mL of deionized water, and 1 mL of nitric acid solution (1 M) was added. After sonication at 60 °C for 110 min, the mixture was transferred to a hydrothermal reactor and reacted at 220 °C for 22 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 0.840 g magnesium nitrate hexahydrate and 2.130 g lanthanum nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B with NaOH and Na2CO3 in a mass ratio of 6:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 8.7. Continue the reaction for 1.5 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 95℃ for 9 h. After filtration, washing and drying, calcine the precipitate at 400℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the ruthenium trichloride solution containing 0.3 wt% Ru to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h, and calcine it at 360℃ for 3.5 h to obtain dehydrogenation catalyst S6.

[0040] Example 7 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 12.56 g of aluminum sulfate octadecylhydrate and 2.75 g of terephthalic acid were dispersed in 30 mL of deionized water, and 3 mL of nitric acid solution (1 M) was added. After sonication at 70 °C for 70 min, the mixture was transferred to a hydrothermal reactor and reacted at 230 °C for 26 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 1.025 g magnesium nitrate hexahydrate and 6.876 g cerium nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B with NaOH and Na2CO3 in a mass ratio of 8:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 8.5. Continue the reaction for 1 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 93℃ for 8 h. After filtration, washing and drying, calcine the precipitate at 500℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the platinum nitrate solution containing 0.5 wt% Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h, and calcine it at 500℃ for 2.5 h to obtain dehydrogenation catalyst S7.

[0041] Example 8 This embodiment discloses a method for preparing the catalyst of the present invention, specifically as follows: (1) 4.69 g aluminum chloride hexahydrate and 3.27 g pyromellitic acid were dispersed in 30 mL of deionized water, 2 mL of nitric acid solution (1M) was added, and the mixture was sonicated at 55 °C for 110 min. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 40 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. (2) Add 1.092 g of stannous chloride dihydrate and 5.565 g of copper nitrate trihydrate to deionized water to prepare salt solution A. Prepare alkaline solution B by mixing NaOH and Na2CO3 in a mass ratio of 5:1. Take 30 g of Al-MOF obtained in step (1) and add it to salt solution A to disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH of the solution is 9.1. Continue the reaction for 2 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 95℃ for 9 h. After filtration, washing and drying, calcine the precipitate at 420℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the platinum nitrate solution containing 0.35 wt% Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 380℃ for 2 h to obtain dehydrogenation catalyst S8.

[0042] Comparative Example 1 Compared to Example 1, this comparative example did not use Al-MOF, but instead used macroporous pseudoboehmite, specifically: (1) Add 1.056 g magnesium nitrate hexahydrate and 5.667 g cerium nitrate hexahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B by mixing NaOH and Na2CO3 in a mass ratio of 6:1. Add 30 g macroporous boehmite to salt solution A and disperse evenly. Stir at room temperature for 1 h. Then add alkaline solution B dropwise to salt solution A at 60℃ until the pH of the solution is 8.5. Continue the reaction for 1 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 95℃ for 9 h. After filtration, washing and drying, calcine the precipitate at 500℃ for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the platinum nitrate solution containing 0.3 wt % Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 400℃ for 2 h to obtain dehydrogenation catalyst D1.

[0043] Comparative Example 2 Compared to Example 1, this comparative example did not use Al-MOF, but instead directly prepared Al2O3 through co-precipitation, specifically as follows: (1) Add 1.056 g magnesium nitrate hexahydrate, 5.667 g cerium nitrate hexahydrate and 220.66 g aluminum nitrate nonahydrate to deionized water to prepare salt solution A. Prepare alkaline solution B by mixing NaOH and Na2CO3 in a mass ratio of 6:1. Add alkaline solution B dropwise to salt solution A at 60°C until the pH of the solution is 8.5. Continue the reaction for 1 h. Then pour the suspension after the reaction into a hydrothermal reactor and age it at 95°C for 9 h. After filtration, washing and drying, calcine the precipitate at 500°C for 3 h under N2 atmosphere to obtain the carrier. (3) Dilute the platinum nitrate solution containing 0.3 wt% Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 400℃ for 2 h to obtain dehydrogenation catalyst D2.

[0044] Comparative Example 3 Compared to Example 1, this comparative example did not contain any additives, specifically: (1) 7.33 g aluminum nitrate nonahydrate and 2.37 g terephthalic acid were dispersed in 30 mL of deionized water, and 3 mL of nitric acid solution (1 M) was added. After sonication at 60 °C for 120 min, the mixture was transferred to a hydrothermal reactor and reacted at 200 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain Al-MOF. The mixture was then calcined at 500 °C for 3 h under N2 atmosphere to obtain the support. (2) Dilute the platinum nitrate solution containing 0.3 wt% Pt to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, dry it at 60℃, 70℃, 85℃, 100℃ and 120℃ for 1 h in a gradient, and calcine it at 400℃ for 2 h to obtain dehydrogenation catalyst D3.

[0045] The dehydrogenation performance of Examples S1-S8 and Comparative Examples D1-D3 obtained in this invention was tested. 5 g of catalyst was packed into a reaction tube with an inner diameter of 10 mm. H2 was introduced at a flow rate of 80 mL / min and reduced at 380 °C for 2 h. After reduction, the heating temperature was set to 350 °C, H2 was turned off, and liquid cyclohexane was introduced, with the liquid hourly space velocity controlled at 1 h. -1 The dehydrogenation reaction was carried out under normal pressure, and the liquid product was analyzed by gas chromatography to determine the conversion rate and selectivity of the dehydrogenation reaction. The test results are shown in Table 1.

[0046] Table 1. Bulk density, specific surface area, conversion rate, and stability data of Examples S1-S8 and Comparative Examples D1-D3

[0047] Comparative Examples S1-S8 show that the catalyst supported on Al-MOF-derived γ-Al₂O₃ exhibits a higher initial conversion rate, and the conversion rate does not decrease significantly after 200 h of reaction, indicating good catalyst stability. Comparative Examples S1 and D1 show that replacing the support from Al-MOF to macroporous alumina worsens catalyst stability, while using co-precipitated alumina in D2 results in even worse catalyst stability. This suggests that the unique structure and large specific surface area of ​​Al-MOF positively contribute to improving the conversion rate and stability of the dehydrogenation catalyst. Comparative Examples S1 and D3 show that the catalyst conversion rate decreases without the addition of auxiliary elements, indicating that the interaction between the auxiliary element and the support contributes to improving the catalyst conversion rate.

[0048] It should be noted that the specific embodiments described above are exemplary, and those skilled in the art can devise various solutions inspired by the disclosure of this invention. These solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a catalyst for efficient and stable hydrogen release from cyclohexane, characterized in that, Includes the following steps: (1) Disperse soluble aluminum salt and organic ligand in deionized water, add acid solution, sonicate at 50~80℃ for 30~120 min, transfer to hydrothermal reactor and react at 150~260℃ for 16~72 h, cool to room temperature after reaction, filter, wash and dry to obtain Al-MOF; (2) Add the additive to deionized water to prepare salt solution A, prepare NaOH and Na2CO3 to prepare alkaline solution B, add the Al-MOF obtained in step (1) to salt solution A and disperse it evenly, stir evenly, then add alkaline solution B dropwise to salt solution A at 60℃ until the pH value of the solution is 8.4~9.2, continue the reaction for 0.5~3 h, then pour the suspension after the reaction into a hydrothermal reactor, age it at 92~105℃ for 8~12 h, filter, wash and dry, then calcine the precipitate under an inert atmosphere to obtain the carrier; (3) Dilute the noble metal salt solution to prepare solution C, pour it into the support prepared in step (2) and stir quickly. After impregnation, perform gradient drying and calcination to obtain the dehydrogenation catalyst.

2. The method for preparing the catalyst for efficient and stable hydrogen release from cyclohexane according to claim 1, characterized in that, The soluble aluminum salt is one of aluminum nitrate, aluminum sulfate, and aluminum chloride; the organic ligand is one or more of terephthalic acid, trimesolic acid, dimethyl terephthalate, and trimesolic acid.

3. The method for preparing the catalyst for efficient and stable hydrogen release from cyclohexane according to claim 1, characterized in that, The additives are nitrates or tin chlorides corresponding to Mg, Ce, La, Cu, Fe, and Co.

4. The method for preparing the catalyst for efficient and stable hydrogen release from cyclohexane according to claim 1, characterized in that, The ratio of NaOH to Na2CO3 in the alkaline solution B is 4~10:

1.

5. The method for preparing the catalyst for efficient and stable hydrogen release from cyclohexane according to claim 1, characterized in that, The noble metal salt solution is a nitrate or chloride solution corresponding to Pt, Pd, Rh, and Ru.

6. A catalyst for the efficient and stable hydrogen release of cyclohexane, characterized in that, It comprises an active component, an auxiliary agent, and a carrier. The active component is a noble metal element from Group VIII, the auxiliary agent is a transition metal element, and the carrier is γ-Al2O3.

7. The catalyst according to claim 7, characterized in that, The specific surface area of ​​the catalyst is not less than 150 m². 2 / g.

8. The catalyst according to claim 7, characterized in that, The catalyst is prepared according to the preparation method described in any one of claims 1-6.

9. The application of the catalyst for efficient and stable hydrogen release from cyclohexane as described in any one of claims 6-8 in aromatic hydrocarbon production or hydrogen storage production.

10. The application of the catalyst for efficient and stable hydrogen release from cyclohexane as described in any one of claims 6-8 in the evaluation of cyclohexane dehydrogenation processes, characterized in that, Evaluation criteria include: The mass of the catalyst was evaluated as 5-10 g; the heating temperature was set at 320-380℃; the reaction was carried out under normal pressure, and the flow rate of cyclohexane was 0.1-0.8 mL / min.

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