A high-stability anti-carbon-deposition organic liquid hydrogen storage material hydrogenation catalyst, a preparation method and application thereof

Abstract

The application provides a preparation method of a high-stability hydrogenation catalyst of an anti-carbon-deposition organic liquid hydrogen storage material, in which active metal Ni and rare earth metal oxide additives are loaded on a carrier by a coprecipitation method to obtain the hydrogenation catalyst. The hydrogenation catalyst prepared by the method has high specific surface area carriers, which can enhance the adsorption capacity of the catalyst and the dispersity of the active metal components, effectively improve the catalytic performance, and simultaneously, the introduction of the rare earth metal oxide modifier can optimize the reaction path, form oxygen vacancies and improve the migration rate of lattice oxygen, effectively inhibit the formation of carbon deposition, and significantly enhance the anti-carbon-deposition performance and cycle stability of the catalyst. The preparation method of the hydrogenation catalyst is mild in process, simple in required equipment, and can be used for large-scale production. In addition, the hydrogenation catalyst has high activity, stability and cycle performance without using noble metals, has good economic benefits, and has a wide popularization and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation catalyst technology, specifically relating to a hydrogenation catalyst for organic liquid hydrogen storage material with high stability against carbon deposition and its preparation method, and also relating to the application of the above catalyst in the catalytic dehydrogenation of organic liquids. Background Technology

[0002] Organic liquid hydrogen storage technology is one of the most promising hydrogen storage technologies for solving the challenges of hydrogen storage and transportation. Developing efficient, stable, and economical hydrogenation catalysts for organic liquid hydrogen storage materials is key to advancing this technology. Currently, commercially available catalysts for hydrogenation of organic liquid hydrogen storage materials typically use noble metals such as Ru and Rh as active components, and their high cost limits their widespread adoption in industrial applications. In contrast, the non-noble metal Ni is abundant and has a lower cost, making it a good alternative to Ru and Rh.

[0003] Patent CN112675865A discloses a supported nickel-based catalyst that exhibits good activity for the catalytic hydrogenation of NPCZ at 150°C and 7 MPa hydrogen pressure. However, its activity decreases after five cycles. Patent CN 117599806A discloses a nano-confined NiRu metal catalyst, in which the catalytic activity decreases during the fifth cycle, specifically, the completion time of the hydrogenation reaction increases from 60 minutes in the first cycle to 180 minutes. These phenomena indicate that although modified nickel-based catalysts possess catalytic activity comparable to noble metal catalysts, improving their stability still faces significant challenges.

[0004] Carbon deposition is one of the key factors leading to the deactivation of nickel-based catalysts. During the hydrogenation process of organic liquid hydrogen storage materials, side reactions involving the breaking of C-C bonds often occur, resulting in the formation of carbonaceous deposits on the catalyst surface. These deposits extensively cover the active sites of the catalyst, significantly reducing its lifetime. The C-C mixture, composed of graphitic carbon and encapsulated carbon, forms the catalyst. γ Carbon is the most stable and most difficult form of carbon to remove. Therefore, researchers have been actively studying and developing methods to remove carbon from the surface of nickel-based catalysts. γ Strategies for carbon buildup.

[0005] In summary, although nickel-based catalysts exhibit activity comparable to noble metal catalysts in the hydrogenation of organic liquid hydrogen storage materials, improving their stability is crucial for their widespread industrial application. Therefore, providing a novel modification method for nickel-based catalysts to enhance the rate of carbon deposition removal and suppress C / C bond breaking side reactions is of great significance for effectively improving catalyst stability and lifespan, and is a technical problem that researchers urgently need to solve. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with a mild preparation process and simple equipment requirements, which is resistant to carbon buildup.

[0007] The second objective of this invention is to provide a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material that resists carbon deposition.

[0008] The third objective of this invention is to provide an application of a hydrogenation catalyst for organic liquid hydrogen storage materials that is resistant to carbon deposition and has high stability, exhibiting good activity and stability in the hydrogenation of organic liquid hydrogen storage materials without the use of precious metals.

[0009] One of the technical solutions adopted by this invention to achieve its objective is: to provide a method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition, comprising the following steps:

[0010] S1. Dissolve the nickel salt, the carrier metal salt, and the rare earth metal salt in water to obtain the first solution; dissolve the precipitant and the ligand in water respectively to obtain the second solution and the third solution;

[0011] S2. Under water bath conditions, the first and second solutions are simultaneously and slowly added dropwise to the third solution while continuously stirring to form a precipitate; the precipitate is separated and washed to obtain the first product.

[0012] S3. Disperse the first product in anhydrous ethanol, then remove the solvent to obtain the second product;

[0013] S4. Grind the second product to obtain powder, and calcine the powder to obtain a catalyst precursor;

[0014] S5. The catalyst precursor is placed in a reducing atmosphere for reduction treatment, and after cooling, it is passivated to obtain the hydrogenation catalyst.

[0015] The rare earth metal salt is selected from any one or a combination of soluble metal salts corresponding to rare earth metals Ce, Y or Eu; in the hydrogenation catalyst, the loading of metallic nickel is 20wt.%-50wt.%, and the doping amount of rare earth metal oxide is 1wt.%-10wt.%.

[0016] The overall concept and inventive principle of this invention are as follows:

[0017] Rare earth metal oxides such as cerium oxide, europium oxide, and yttrium oxide possess unique oxygen storage capabilities, enabling them to store and release oxygen species on the catalyst surface, thus improving the catalyst's rate of carbon deposition removal. Simultaneously, the addition of rare earth metal oxides optimizes the reaction pathway and suppresses side reactions involving C / C bond breaking. These characteristics make doping nickel-based catalysts with rare earth metal oxides a novel strategy for improving catalyst lifetime. Therefore, the hydrogenation catalyst preparation method provided by this invention, through a co-precipitation method, loads active metal Ni and rare earth metal oxide promoters onto a support, thereby obtaining a hydrogenation catalyst exhibiting good activity and stability for the hydrogenation of organic liquid hydrogen storage materials without the use of precious metals.

[0018] Further research revealed that while different types of rare earth metal oxides all possess a certain oxygen storage capacity, the temperatures at which oxygen vacancies form differ. For example, La₂O₃ readily generates oxygen vacancies at high temperatures (around 750°C), but high-temperature treatment easily leads to the aggregation of Ni nanoparticles. This invention, through screening and comparison, uses soluble metal salts corresponding to rare earth metals Ce, Y, or Eu as the rare earth metal salts, resulting in hydrogenation catalysts doped with CeO₂, Y₂O₃, or Eu₂O₃. 3， Oxygen vacancies can be formed at relatively low temperatures (300-350℃), utilizing their oxygen storage capacity to remove carbon deposits. Furthermore, CeO2, Y2O3, or Eu2O3 can prevent Ni nanoparticles from being covered. When the loading of metallic nickel in the hydrogenation catalyst is controlled at 20wt.%-50wt.% and the doping amount of rare earth metal oxides is controlled at 1wt.%-10wt.%, it exhibits better anti-carbon deposition effects and further improves the catalyst's cycle stability.

[0019] Preferably, in the hydrogenation catalyst, when the loading of metallic nickel is controlled at 30wt.%-50wt.% and the doping amount of rare earth metal oxide is 3wt.%-5wt.%, the catalytic performance of the hydrogenation catalyst remains above 90% of that of the initial use after 10 cycles.

[0020] Further, in step S1, the nickel salt includes one or more combinations of Ni(NO3)2·6H2O, NiCl2·6H2O, and NiSO4·6H2O; the support metal salt includes one or more combinations of Al(NO3)2·9H2O, Ti(NO3)4, and Mg(NO3)2.

[0021] Further, the rare earth metal salt includes one or more combinations of soluble nitrates, soluble sulfates, soluble acetates, and soluble chlorides corresponding to rare earth metals Ce, Y, or Eu; preferably, the rare earth metal salt is selected from any one of Ce(NO3)4, Y(NO3)3·9H2O, and Eu(NO3)3·9H2O.

[0022] Further, in step S1, the precipitant includes one or more combinations of Na2CO3, K2CO3, NaHCO3, and Na2SO3; the coordinating agent includes one or more combinations of polyethylene glycol, polydextrose, and fructooligosaccharide.

[0023] Among them, the precipitant will Ni 2+ Ce 4+ Y 3+ and Eu 3+ Precipitation, the specific reaction equation is as follows:

[0024] Ni 2+ +CO3 2- →NiCO3↓;

[0025] Ce 4+ +2CO3 2- +2H₂O→Ce(OH)₄↓+2CO₂↑;

[0026] 2Y 3+ +3CO3 2- +3H₂O→2Y(OH)₃↓+3CO₂↑;

[0027] 2Eu 3+ +3CO3 2- +3H2O→2Eu(OH)3↓+3CO2↑.

[0028] Coordinating agents are used to coordinate with metal ions. Taking polyethylene glycol (PEG) as an example, the oxygen atoms in the PEG molecule have lone pairs of electrons, which can coordinate with metal ions. This coordination effect makes the catalyst growth and nucleation process more regular, and the precipitate can be removed during subsequent washing with water and ethanol, avoiding residue.

[0029] Preferably, in step S1, the precipitant is Na2CO3 and the coordinating agent is polyethylene glycol (PEG). The polyethylene glycol includes any one of PEG 200, PEG600, PEG2000, and PEG20000.

[0030] Furthermore, in step S2, the water bath temperature is 70-100°C; in step S3, the solvent removal method includes: azeotropic evaporation of water and anhydrous ethanol under oil bath conditions of 90-150°C. Step S3 first disperses the first product in anhydrous ethanol and then removes the solvent, which can disperse the precipitate, prevent large-scale aggregation of precipitate particles, and facilitate rapid evaporation of the product.

[0031] Furthermore, in step S4, the calcination temperature is 400-800℃ and the time is 1-3h.

[0032] Furthermore, in step S5, the reducing atmosphere is a mixture of inert gas and hydrogen, with a flow rate of 50-90 mL / min.

[0033] Furthermore, in step S5, the reduction treatment temperature is 550-750℃ and the time is 3-6h.

[0034] Further, in step S5, the passivation treatment includes: introducing a mixture of inert gas and oxygen into the cooled product for 0.5-2 hours. In step S5, the newly prepared Ni catalyst obtained through gas-phase reduction has a small particle size and relatively active chemical properties, making it prone to severe oxidation or even combustion when directly exposed to air. After cooling the catalyst to room temperature, introducing a mixture of inert gas and O2 allows for slow oxidation of the Ni catalyst surface, forming a thin film of nickel oxide on the surface and preventing further oxidation of Ni.

[0035] The second objective of this invention is achieved by providing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition, prepared by the method described in the first objective of this invention; the specific surface area of ​​the hydrogenation catalyst is 100-400 m². 2 / g, pore volume of 0.2-1.4cm 3 / g, pore size is 5-25nm.

[0036] The hydrogenation catalyst prepared by this invention uses one of Al2O3, TiO2, and MgO as a support, and one of rare earth metal oxides CeO2, Y2O3, and Eu2O3 as a modifier, with metallic nickel as the active component. In the hydrogenation catalyst, the loading of metallic nickel is 20 wt.%-50 wt.%, the particle size of metallic nickel is 5-15 nm, and the doping amount of rare earth metal oxide is 1 wt.%-10 wt.%.

[0037] The hydrogenation catalyst prepared by this invention has a good physical structure: on the one hand, it uses a support with a high specific surface area to support the active metal Ni, and the high specific surface area plays a positive role in exerting the catalytic activity of the active component and the adsorption of reactants and gases; on the other hand, the rare earth metal oxides CeO2, Y2O3, and Eu2O3 have the functions of forming oxygen vacancies and increasing the migration rate of lattice oxygen, which effectively inhibits the formation of carbon deposits during the catalytic process and further improves the catalytic stability.

[0038] The third objective of this invention is achieved by providing an application of the hydrogenation catalyst for the anti-carbon-deposition, high-stability organic liquid hydrogen storage material according to the second objective of this invention. The hydrogenation catalyst is used in the hydrogenation reaction of the organic liquid hydrogen storage material, wherein the organic liquid hydrogen storage material includes one or more combinations of N-propylcarbazole, N-ethylcarbazole, toluene, dibenzyltoluene, 1-methylindole, and 1,2-dimethylindole.

[0039] Furthermore, the application conditions include: mixing the hydrogenation catalyst with the organic liquid hydrogen storage material at a mass ratio of 1:(5-15), then adding 1,4-dioxane as a solvent, with a reaction pressure of 6-8 MPa, a reaction temperature of 130-170℃, and a stirring speed of 500-700 rpm / min.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] (1) The method for preparing a hydrogenation catalyst for organic liquid hydrogen storage materials with high stability and resistance to carbon deposition provided by the present invention involves loading active metal Ni and rare earth metal oxide promoters onto a support via a co-precipitation method to obtain a hydrogenation catalyst that exhibits good activity and stability for hydrogenation of organic liquid hydrogen storage materials without the use of precious metals. The preparation method provided by the present invention is mild, requires simple equipment, and can be used for large-scale production. The catalyst obtained by the present invention still has high activity and stability without the use of precious metals, and has good economic benefits.

[0042] (2) The hydrogenation catalyst of the organic liquid hydrogen storage material with high stability against carbon deposition prepared by the present invention has high activity and stability. On the one hand, the present invention utilizes a high specific surface area support to enhance the adsorption capacity of the catalyst and the dispersibility of the active metal components, effectively improving the catalytic performance. On the other hand, the introduction of rare earth metal oxide modifiers optimizes the reaction path, effectively inhibits the formation of carbon deposits by forming oxygen vacancies and increasing the lattice oxygen migration rate, and significantly enhances the anti-carbon deposition performance and cycle stability of the catalyst.

[0043] (3) The rare earth metal oxides doped in the hydrogenation catalyst prepared in this invention are selected from CeO2, Y2O3 or Eu2O3. These rare earth metal oxides can form oxygen vacancies at low temperatures, and their oxygen storage capacity is used to remove carbon deposits. In addition, the advantage of CeO2, Y2O3 or Eu2O3 in forming oxygen vacancies at low temperatures can also prevent Ni nanoparticles from being covered, thereby improving the anti-carbon deposition effect and further enhancing the cycle stability of the catalyst. Attached Figure Description

[0044] Figure 1 The N2 physical adsorption-desorption curve of the hydrogenation catalyst prepared in Example 1;

[0045] Figure 2 The pore size distribution diagram is shown for the hydrogenation catalyst prepared in Example 1.

[0046] Figure 3 Transmission electron microscope image of the hydrogenation catalyst prepared in Example 1;

[0047] Figure 4 The particle size distribution diagram is shown for the hydrogenation catalyst prepared in Example 1.

[0048] Figure 5 The distribution curve of hydrogenation products of N-propylcarbazole (NPCZ) prepared by the hydrogenation catalyst in Example 1 as a function of time;

[0049] Figure 6 The hydrogen uptake of the hydrogenation catalyst prepared in Example 1 during 10 hydrogenation cycles of NPCZ varies with time.

[0050] Figure 7 The TG curve of NPCZ after 10 cycles of reaction catalyzed by the hydrogenation catalyst prepared in Example 1 is shown.

[0051] Figure 8 The image shows the DSC diagram of NPCZ after 10 cycles of reaction catalyzed by the hydrogenation catalyst prepared in Example 1.

[0052] Figure 9 Raman plot of NPCZ after 10 cycles of reaction catalyzed by the hydrogenation catalyst prepared in Example 1;

[0053] Figure 10 The distribution curve of hydrogenation products of NPCZ prepared by the hydrogenation catalyst of Comparative Example 1 as a function of time;

[0054] Figure 11 The hydrogen uptake of the hydrogenation catalyst prepared for Comparative Example 1 during 10 hydrogenation cycles of NPCZ varies with time.

[0055] Figure 12TG curve of NPCZ after 10 cycles of reaction catalyzed by the hydrogenation catalyst prepared in Comparative Example 1;

[0056] Figure 13 DSC image of NPCZ after 10 cycles of reaction catalyzed by the hydrogenation catalyst prepared in Comparative Example 1;

[0057] Figure 14 Raman plot of NPCZ after 10 cycles of reaction catalyzed by the hydrogenation catalyst prepared in Comparative Example 1;

[0058] Figure 15 The hydrogen absorption curves for ten hydrogenation reactions of NPCZ catalyzed by the hydrogenation catalysts prepared in Examples 1-6 and Comparative Examples 1-5 are shown (each hydrogenation reaction lasted 120 min). Detailed Implementation

[0059] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0061] This invention provides a method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition, comprising the following steps:

[0062] Step 1: Dissolve the nickel salt, the carrier metal salt, and the rare earth metal salt in water to obtain the first solution; dissolve the precipitant and the complexing agent in water respectively to obtain the second and third solutions;

[0063] The rare earth metal salt is selected from any one of Ce(NO3)4, Y(NO3)3·9H2O, and Eu(NO3)3·9H2O; the nickel salt includes one or more combinations of Ni(NO3)2·6H2O, NiCl2·6H2O, and NiSO4·6H2O; the support metal salt includes any one of Al(NO3)2·9H2O, Ti(NO3)4, and Mg(NO3)2; the precipitant includes one or more combinations of Na2CO3, K2CO3, NaHCO3, and Na2SO3; and the coordinating agent includes one or more combinations of polyethylene glycol, polydextrose, and fructooligosaccharide.

[0064] Step 2: Under a water bath at 70-100℃, the first and second solutions are simultaneously and slowly added dropwise to the third solution while continuously stirring to form a precipitate; the precipitate is separated and washed to obtain the first product.

[0065] Step 3: Disperse the first product in anhydrous ethanol, and then evaporate the water and anhydrous ethanol in an oil bath at 90-150°C to remove the solvent, thereby obtaining the second product.

[0066] Step 4: Grind the second product to obtain powder, and calcine the powder at a temperature of 400-800℃ for 1-3 hours to obtain the catalyst precursor.

[0067] Step 5: The catalyst precursor is placed in a reducing atmosphere for reduction treatment at a temperature of 550-750℃ for 3-6 hours; a mixture of inert gas and oxygen is introduced into the cooled product for 0.5-2 hours for passivation treatment to obtain the hydrogenation catalyst; in the hydrogenation catalyst, the loading of metallic nickel is 20wt.%-50wt.%, and the doping amount of rare earth metal oxide is 1wt.%-5wt.%.

[0068] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0069] The main parameters and experimental conditions involved in the various embodiments and comparative examples of this invention are shown in Table 1 below:

[0070] Table 1

[0071]

[0072] Example 1

[0073] A method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material resistant to carbon deposition, comprising the following steps:

[0074] (1) Weigh out 7.4320g of Ni(NO3)2·6H2O, 0.7439g of Ce(NO3)4, and 12.3400g of Al(NO3)3·9H2O and dissolve them in deionized water to form solution A'. Weigh out 15.7826g of Na2CO3 and dissolve it in deionized water to form solution B'. Weigh out 0.5g of PEG2000 and dissolve it in deionized water to form solution C'.

[0075] (2) Under 90°C water bath conditions, solutions A' and B' are slowly added dropwise to solution C', and the mixture is stirred continuously to form a light green precipitate. After filtering the precipitate, it is washed with deionized water and anhydrous ethanol until the washing solution is neutral.

[0076] (3) Disperse the precipitate obtained in step (2) in anhydrous ethanol, and evaporate the water and anhydrous ethanol azeotropically under oil bath conditions at 120°C;

[0077] (4) The obtained solid was ground into powder and placed in a muffle furnace and calcined at 600°C for 1 h. After cooling to room temperature, a dark green powder catalyst precursor was obtained.

[0078] (5) Transfer the catalyst precursor powder from step (4) to a tube furnace, introduce Ar / H2 mixed gas A (H2 volume content is 10%, gas flow rate is 70 ml / min), calcine at 650℃ for 6 h, and then cool to room temperature. Then introduce Ar / O2 mixed gas B (O2 volume content is 1%, gas flow rate is 70 ml / min) for 1 h passivation to obtain Ni / CeO2-Al2O3 catalyst supported on CeO2 and Al2O3 composite support, wherein the theoretical loading of Ni is 30 wt%, the theoretical doping of CeO2 is 5 wt%, and the catalyst is denoted as Ni30 / Ce5Al.

[0079] The physical adsorption-desorption curves of the Ni30 / Ce5Al catalyst are as follows: Figure 1 As shown, the aperture distribution is as follows Figure 2 As shown, from Figure 1 It can be seen that the Ni30 / Ce5Al catalyst exhibits a type IV adsorption isotherm, indicating that the prepared sample forms a mesoporous structure, and the catalyst has a specific surface area of ​​322 m². 2 / g, Figure 2 The catalyst pore structure distribution was further explained. The pore volume of the catalyst was calculated to be 1.26 cm³ using the Barrett-Joyner-Halenda (BJH) method. 3 / g, with an average pore size of 14.50nm.

[0080] The transmission electron microscope image of the catalyst is shown below. Figure 3 As shown, from Figure 3 As can be seen, the active metallic nickel is highly dispersed on the catalyst surface in the form of nanoclusters. The particle size distribution of the catalyst is shown in the figure below. Figure 4 As shown, from Figure 4 It can be seen that the average particle size of this new catalyst is 9.91 nm.

[0081] Example 2

[0082] A method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition is described in Example 1. The main difference from Example 1 is that the raw materials weighed in step (1) are 6.08g NiCl2·6H2O, 10.73g Ti(NO3)4, 0.7446g Y(NO3)3·9H2O, and 13.8744g Na2CO3. 0.5g PEG200 is used to dissolve the Na2CO3 in deionized water to form solution C'. The resulting catalyst is Ni30 / Y5Ti.

[0083] Example 3

[0084] A method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition is described in Example 1. The main difference from Example 1 is that the raw materials weighed in step (1) are 6.72 g NiSO4·6H2O, 11.99 g Mg(NO3)2, 0.7446 g Eu(NO3)3·9H2O, and 13.8378 g Na2CO3. 0.5 g PEG600 is used to dissolve the Na2CO3 in deionized water to form solution C'. The resulting catalyst is Ni30 / Eu5Mg.

[0085] Example 4

[0086] A method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition is described in Example 1. The main difference from Example 1 is that the raw materials weighed in step (1) are: nickel nitrate hexahydrate Ni(NO3)2·6H2O: 7.4320g, aluminum nitrate nonahydrate Al(NO3)3·9H2O: 12.1900g, cerium nitrate Ce(NO3)4: 0.4463g, and anhydrous sodium carbonate Na2CO3: 16.0090g. 0.5g of PEG2000 is dissolved in deionized water to form solution C'. The catalyst is denoted as Ni30 / Ce3Al.

[0087] Example 5

[0088] A method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition is described in Example 1. The main difference from Example 1 is that the raw materials weighed in step (1) are: nickel nitrate hexahydrate Ni(NO3)2·6H2O: 7.4320g, aluminum nitrate nonahydrate Al(NO3)3·9H2O: 11.020g, cerium nitrate Ce(NO3)4: 1.4878g, and anhydrous sodium carbonate Na2CO3: 15.2165g. 0.5g of PEG2000 is dissolved in deionized water to form solution C'. The catalyst is designated as Ni30 / Ce10Al.

[0089] Example 6

[0090] A method for preparing a hydrogenation catalyst for a highly stable organic liquid hydrogen storage material with resistance to carbon deposition is described in Example 1. The main difference from Example 1 is that the raw materials weighed in step (1) are: nickel nitrate hexahydrate Ni(NO3)2·6H2O: 12.38 g, aluminum nitrate nonahydrate Al(NO3)3·9H2O: 8.31 g, cerium nitrate Ce(NO3)4: 0.7439 g, and anhydrous sodium carbonate Na2CO3: 14.2074 g. 0.5 g of PEG2000 is dissolved in deionized water to form solution C'. The catalyst is denoted as Ni50 / Ce5Al.

[0091] Comparative Example 1

[0092] A method for preparing a hydrogenation catalyst Ni30 / Al2O3, the steps of which are as described in Example 1; the difference is that in step (1) of Comparative Example 1, the raw materials weighed are 7.4320 g of Ni(NO3)2·6H2O and 25.77 g of Al(NO3)3·9H2O. The weight of Na2CO3 is 16.3579 g. The catalyst is designated as Ni30 / Al2O3.

[0093] Comparative Example 2

[0094] A method for preparing a hydrogenation catalyst Ni30 / TiO2 is described, with steps as in Example 2. The difference lies in that in step (1) of Comparative Example 2, the raw materials weighed are 6.0749 g NiCl2·6H2O, 12.9665 g Ti(NO3)4, and 14.3982 g Na2CO3, which are dissolved in deionized water using 0.5 g PEG200 to form solution C'. The resulting catalyst is Ni30 / TiO2.

[0095] Comparative Example 3

[0096] A method for preparing a hydrogenation catalyst Ni30 / MgO is described, with steps as in Example 3; the difference lies in that in step (1) of Comparative Example 3, the raw materials weighed are 6.7179 g NiSO4·6H2O, 12.8796 g Mg(NO3)2, and 14.2957 g Na2CO3, which are dissolved in deionized water using 0.5 g PEG600 to form solution C'. The resulting catalyst is Ni30 / MgO.

[0097] Comparative Example 4

[0098] A method for preparing a hydrogenation catalyst Ni10 / Ce5Al is described, with steps as in Example 1; the difference lies in the raw materials weighed in step (1) of Comparative Example 4: 2.4700 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O, 15.6500 g of aluminum nitrate nonahydrate Al(NO3)3·9H2O, 0.7439 g of cerium nitrate Ce(NO3)4, and 17.3578 g of anhydrous sodium carbonate Na2CO3. 0.5 g of PEG2000 is dissolved in deionized water to form solution C'. The catalyst is designated as Ni10 / Ce5Al.

[0099] Comparative Example 5

[0100] A method for preparing a hydrogenation catalyst Ni70 / Ce5Al is described, with steps as in Example 1; the difference lies in the raw materials weighed in step (1) of Comparative Example 5: nickel nitrate hexahydrate Ni(NO3)2·6H2O: 17.28 g, aluminum nitrate nonahydrate Al(NO3)3·9H2O: 4.61 g, cerium nitrate Ce(NO3)4: 0.7439 g, and anhydrous sodium carbonate Na2CO3: 12.6323 g. 0.5 g of PEG2000 is dissolved in deionized water to form solution C'. The catalyst is designated as Ni70 / Ce5Al.

[0101] Application performance testing

[0102] Using 0.2 g of the catalyst prepared in Example 1, 2.0 g of NPCZ as the hydrogen storage material, and 40 ml of n-hexane as the solvent, the reaction pressure was 7 MPa, the reaction temperature was 150 °C, the rotation speed was 600 rpm / min, and the reaction time was 25 min to achieve complete hydrogenation of NPCZ without any other byproducts. The hydrogenation reaction components of this catalyst for NPCZ are as follows: Figure 5 As shown, from Figure 5 It can be seen that the Ni30 / Ce5Al catalyst prepared in Example 1 completes hydrogenation within 25 minutes.

[0103] Ten cyclic hydrogenation experiments of the catalyst were conducted at 150℃ and 7 MPa. After each hydrogenation, the catalyst was not treated in any way before the next experiment. The hydrogen absorption rate versus time curves for the ten hydrogenation cycles are shown below. Figure 6 As shown, after 10 cycles of hydrogenation reaction, the Ni30 / Ce5Al catalyst prepared in Example 1 was still able to achieve complete hydrogenation of NPCZ within 120 minutes, indicating that the catalyst has good stability and can be used multiple times.

[0104] The TG results of the catalyst after cycling are as follows: Figure 7 As shown, the test atmosphere was air, and the catalyst weight loss rate was 8.79%. DSC was used to analyze the types of carbon deposits, and the results are as follows. Figure 8As shown, the Ni30 / Ce5Al catalyst exhibits less graphite carbon deposition above 500°C, indicating that graphite carbon formation is suppressed during the catalytic process.

[0105] The properties and structure of the carbonaceous material formed on the catalyst prepared in Example 1 after 10 cycles were studied using Raman spectroscopy. The Ni30 / Ce5Al catalyst prepared in Example 1 had an ID / IG ratio of 1.09, indicating a low degree of carbon deposition and graphitization, which was relatively easy to remove.

[0106] The performance testing procedure for the Ni30 / Al2O3 catalyst prepared in Comparative Example 1 was the same as that in Example 1. The catalyst's reaction with the hydrogenation components of NPCZ was as follows: Figure 10 As shown, the Ni / Al2O3 catalyst completed hydrogenation within 60 minutes. The stability test of the Ni30 / Al2O3 catalyst prepared in Comparative Example 1 was the same as in Example 1; the hydrogen absorption rate over time after 10 hydrogen additions is shown in the curves. Figure 11 As shown, the Ni30 / Al2O3 catalyst prepared in Comparative Example 1 can achieve complete hydrogenation within 120 min in the first five reactions. The catalytic activity decreases significantly starting from the sixth reaction, and the amount of hydrogen added in the 10th hydrogenation reaction is 3.91 wt.

[0107] The TG results of the catalyst in Comparative Example 1 after cycling are as follows: Figure 12 As shown, the test atmosphere was air, and the catalyst weight loss rate was 17.6%. DSC was used to analyze the types of carbon deposits, and the results are as follows. Figure 13 As shown, the recycled Ni / Al2O3 catalyst contains a large amount of C that has been oxidized at 300-500°C. β This species can affect the catalytic activity of Ni30 / Al2O3, leading to catalyst deactivation.

[0108] The Raman spectrum of the recycled Ni30 / Al2O3 catalyst is as follows: Figure 14 As shown, I D / I G The value is 0.88, indicating a high degree of carbon graphitization on the catalyst surface, resulting in a more ordered structure that is more difficult to remove and thus affecting catalytic activity.

[0109] Furthermore, Figure 15 The hydrogen absorption curves of the catalysts prepared in Examples 1-6 and Comparative Examples 1-5 for catalyzing ten hydrogenation reactions of NPCZ are shown (each hydrogenation reaction lasted 120 min). Table 2 shows the hydrogen absorption of the catalysts prepared in each example and comparative example for the first use, the hydrogen absorption of the catalyst in the 10th cycle, and the catalytic performance retention rate of the catalyst after 10 cycles.

[0110] Table 2

[0111]

[0112] Depend on Figure 15 And Table 2,

[0113] Based on the test results of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, it can be seen that after doping with a certain amount of rare earth metal oxide additives CeO2, Y2O3 or Eu2O3, the catalyst has strong stability and can still maintain high catalytic activity after 10 hydrogenation cycle experiments, while the unmodified catalyst is significantly deactivated after 10 hydrogenation experiments.

[0114] Based on the test results of Examples 1, 4, and 5, it is evident that appropriate CeO2 has a positive impact on improving catalyst activity, but excessive CeO2 will decrease catalytic performance. This may be because excessive CeO2 clogs the catalyst channels, leading to a decrease in specific surface area and causing Ni nanoparticles to agglomerate. Therefore, controlling the doping amount of rare earth metal oxides to 3wt.%-5wt.% helps to further improve the catalyst's cycle performance.

[0115] Based on the test results of Examples 1, 5, 4, and 5, it can be seen that the catalyst exhibits optimal activity and stability when the Ni loading is controlled between 30 wt.% and 50 wt.%. This may be because when the Ni loading is low, the interaction between Ni and the catalyst support is stronger, forming more thermally stable NiAl2O4, which reduces the reducibility of Ni; while excessively high Ni loading can cause Ni nanoparticles to agglomerate during the reaction.

[0116] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. The application of a carbon-resistant, highly stable organic liquid hydrogen storage material hydrogenation catalyst in the hydrogenation reaction of N-propylcarbazole, characterized in that, The reaction conditions for the application are as follows: 0.2 g of hydrogenation catalyst and 2.0 g of N-propylcarbazole were reacted in hexane as solvent at a reaction pressure of 7 MPa and a reaction temperature of 150 °C. Under these reaction conditions, the hydrogenation catalyst achieved complete hydrogenation of N-propylcarbazole within 25 minutes. Furthermore, after 10 consecutive cycles of hydrogenation tests under these conditions, it still achieved complete hydrogenation of N-propylcarbazole within 120 minutes. The preparation method of the hydrogenation catalyst includes the following steps: S1. Dissolve the nickel salt, the carrier metal salt, and the rare earth metal salt in water to obtain the first solution; dissolve the precipitant and the ligand in water respectively to obtain the second solution and the third solution; S2. Under water bath conditions, the first and second solutions are simultaneously and slowly added dropwise to the third solution while continuously stirring to form a precipitate; the precipitate is separated and washed to obtain the first product. S3. Disperse the first product in anhydrous ethanol, then remove the solvent to obtain the second product; S4. Grind the second product to obtain powder, and calcine the powder to obtain a catalyst precursor; S5. The catalyst precursor is placed in a reducing atmosphere for reduction treatment, cooled, and then passivated to obtain the hydrogenation catalyst. The rare earth metal salt is Ce(NO3)4; the support metal salt is Al(NO3)3·9H2O; in the hydrogenation catalyst, the loading of nickel is 30 wt.% and the doping amount of rare earth metal oxide is 5 wt.%.

2. The application according to claim 1, characterized in that, In step S1, the nickel salt includes one or more combinations of Ni(NO3)2·6H2O, NiCl2·6H2O, and NiSO4·6H2O.

3. The application according to claim 1, characterized in that, In step S1, the precipitant includes one or more combinations of Na2CO3, K2CO3, NaHCO3, and Na2SO3; the coordinating agent includes one or more combinations of polyethylene glycol, polydextrose, and fructooligosaccharide.

4. The application according to claim 1, characterized in that, In step S2, the temperature of the water bath is 70-100℃; in step S3, the solvent removal method includes: azeotropic evaporation of water and anhydrous ethanol under oil bath conditions of 90-150℃.

5. The application according to claim 1, characterized in that, In step S4, the calcination temperature is 400-800℃ and the time is 1-3h.

6. The application according to claim 1, characterized in that, In step S5, the reducing atmosphere is a mixture of inert gas and hydrogen, with a flow rate of 50-90 mL / min.

7. The application according to claim 1, characterized in that, In step S5, the reduction treatment temperature is 550-750℃ and the time is 3-6h.

8. The application according to claim 1, characterized in that, In step S5, the passivation treatment includes: introducing a mixture of inert gas and oxygen into the cooled product for 0.5-2 hours.

9. The application according to claim 1, characterized in that, The specific surface area of ​​the hydrogenation catalyst for the aforementioned carbon-resistant, highly stable organic liquid hydrogen storage material is 100-400 m². 2 / g, pore volume 0.2-1.4cm 3 / g, pore size is 5-25nm.

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