Catalyst for circulating hydrogen storage of 1, 4-butanediol / gamma-butyrolactone as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for circulating hydrogen storage of 1, 4-butanediol / gamma-butyrolactone as well as a preparation method and application of the catalyst, and belongs to the technical field of catalysts. The catalyst comprises bimetallic active components CuO and AgO, a skeleton component, a rare earth auxiliary agent and calcium stearate, the skeleton component comprises CeO2 and at least one of the following oxides: ZnO, TiO2, ZrO2, MoO3 and Al2O3; on the basis of the total mass of the catalyst, the content of CuO is 55-80 wt%, and the content of AgO is 0.5-1.5 wt%; the total content of the skeleton component is 15-42 wt%, wherein the content of CeO2 is 10-38 wt%; the content of the rare earth additive oxide is 1-5wt%; and the content of calcium stearate is 1.5-4.5 wt%. The preparation method comprises the following steps: preparing a carrier precursor through a coprecipitation method; auxiliary loading and crystal phase regulation and control; and post-processing and forming. The catalyst provided by the invention completely avoids the use of elements harmful to the environment, and has high activity, high selectivity, excellent carbon deposition resistance and long-period stability.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a catalyst for 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage, its preparation method, and its application. Background Technology

[0002] Hydrogen is an important chemical raw material and a promising green energy carrier. Global annual hydrogen production exceeds 95 million tons, with China producing over 33 million tons. Hydrogen energy has become a crucial direction for global energy transition, with its entire industrial chain encompassing three key links: hydrogen production, storage, transportation, and utilization. Due to hydrogen's high energy density and unique chemical properties, the most significant challenge facing hydrogen energy development lies in its storage and transportation. Existing hydrogen storage technologies mainly include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, organic liquid hydrogen storage (LOHC), and solid-state hydrogen storage. Among these, high-pressure gaseous hydrogen storage is the most mature. LOHC, as an emerging hydrogen storage method, possesses advantages such as high hydrogen density and good safety, making it particularly suitable for long-distance hydrogen storage and transportation. For hydrogen transportation distances exceeding 100 kilometers, LOHC has demonstrated significant cost advantages. LOHC technology allows hydrogen to be seamlessly integrated into existing storage and transportation infrastructure, releasing high-purity hydrogen through a catalytic dehydrogenation process when needed.

[0003] Among numerous liquid hydrocarbon supports, the 1,4-butanediol (BDO) / γ-butyrolactone (GBL) combination shows great potential. BDO exhibits a high hydrogen storage capacity (4.4 wt%) among diols and outperforms other liquid hydrocarbon supports in terms of feedstock resources, production scale, toxicity, and price. Therefore, developing highly selective and stable dehydrogenation / hydrogenation catalysts to promote the practical application of BDO-GBL cyclic hydrogen storage technology is of significant practical importance.

[0004] Currently, various BDO dehydrogenation catalysts or GBL hydrogenation catalysts have been developed and applied in the field of hydrogen storage. For example, patent publication number CN116173977 A discloses a dehydrogenation catalyst prepared by a stepwise precipitation method, which consists of 20% CuO. 50%, ZnO 15% 40%, ZrO2 10% 30%, TiO25% 20%, CrO 31% 10%, Ce2O3 1% Composition: 10%. This catalyst exhibits good catalytic activity, selectivity, and stability, but contains environmentally harmful hexavalent chromium, placing high demands on the catalyst production process. Patent CN115106094 A discloses a Cu, Cr, Gd / Ce, Mg, Al, and Zr catalyst for alcohol dehydrogenation. It improves Cu element dispersion by strictly controlling the pH value of a multi-step precipitation process to prepare a hydrotalcite structure; however, this catalyst also contains chromium. Patent CN117654528 A discloses a supported Cu-Cr-X (Zn, Ga, In, Sn, Bi)-Y (Mg, Ca, Sr, Ba) dehydrogenation catalyst. Cr, element X, and element Y improve the selectivity of the dehydrogenation cyclization main product, reduce reaction byproducts, and resist coking and sintering; simultaneously, its low Cr and low Cu content prevents excessive reaction concentration and a low cooling point. Patent CN119869533 A discloses a 1,4 This patent discloses a method for producing GBL from BDO via BDO dehydrogenation. The method involves preparing a copper salt, zinc salt, and aluminum salt solution, mixing them uniformly with a biological template, and adding them in a co-current manner using an acid-base co-precipitation process to prevent Cu agglomeration, embedding, and sintering, thereby improving the catalyst's conversion rate, selectivity, and stability. Patent CN103044367A discloses a method for producing GBL via BDO dehydrogenation, using a CuO-ZnO-Al2O3 catalyst prepared by co-precipitation and impregnating it with K and / or Li as promoters. This catalyst achieves a BDO dehydrogenation conversion rate of over 98% under conditions of relatively low temperature, high liquid hourly space velocity, and a suitable hydrogen / alcohol ratio. Patent CN116281851A discloses a Cu-based catalyst for the hydrogenation of γ-butyrolactone, with one or more of SiO2, Cr2O3, ZnO, ZrO2, and Al2O3 as supports, capable of catalyzing the hydrogenation of γ-butyrolactone at 140 ℃ to 200 ℃.

[0005] While the aforementioned technologies have improved the catalytic performance of the BDO-GBL cycle to some extent, several key issues remain to be addressed: First, most existing high-performance catalysts rely on Cr-containing components, posing environmental risks and production limitations. Second, Cr-free catalysts (such as Cu-Zn-based catalysts) generally suffer from excessive acidity, easily triggering side reactions such as dehydration to tetrahydrofuran or deep hydrogenation to n-butanol, leading to a decrease in the selectivity of the target product GBL. Furthermore, alkali metal or alkaline earth metal promoters introduced into some catalysts are prone to loss during the reaction, causing sintering of active components and catalyst structural instability, affecting long-term operational reliability. Therefore, developing environmentally friendly, highly selective, and highly stable Cr-free dehydrogenation / hydrogenation catalysts has become an urgent need to promote the development of LOHC hydrogen storage technology. Summary of the Invention

[0006] One of the objectives of this invention is to provide a catalyst for 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage that completely avoids the use of environmentally harmful elements (such as hexavalent chromium) and has high activity, high selectivity, excellent anti-carbon deposition performance and long-term stability, thus meeting the actual industrial requirements of efficient and stable operation of catalysts under mild reaction conditions in BDO / GBL cycles in LOHC systems.

[0007] A second objective of this invention is to provide a method for preparing the aforementioned catalyst.

[0008] A third objective of this invention is to provide applications of the aforementioned catalyst.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention discloses a catalyst for cyclic hydrogen storage of 1,4-butanediol / γ-butyrolactone, characterized in that the catalyst comprises a bimetallic active component, a framework component, a rare earth additive and calcium stearate; The bimetallic active components are CuO and AgO; The skeletal components include CeO2 and at least one of the following oxides: ZnO, TiO2, ZrO2, MoO3, and Al2O3. The rare earth additive is at least one of Nd, Pr, Y, Ce, and La; Based on the total mass of the catalyst, the CuO content is 55~80 wt%, the AgO content is 0.5~1.5 wt%, the total content of the framework components is 15~42 wt%, of which the CeO2 content is 10~38 wt%, the rare earth auxiliary oxide content is 1~5 wt%, and the calcium stearate content is 1.5~4.5 wt%.

[0010] In some embodiments of the present invention, based on the total mass of the catalyst, the CuO content is 55-75 wt%, the AgO content is 0.5-1.2 wt%, the total content of the framework components is 20-40 wt%, of which the CeO2 content is 15-35 wt%, the rare earth auxiliary oxide content is 2-3 wt%, and the calcium stearate content is 2.5-4.5 wt%. Preferably, based on the total mass of the catalyst, its composition is CuO 58 wt%, AgO 1.0 wt%, CeO2 20 wt%, ZnO 10 wt%, TiO2 6 wt%, Nd2O3 3 wt%, and calcium stearate 2.0 wt%.

[0011] In some embodiments of the present invention, the catalyst is in the form of a porous cylinder; preferably a three-hole cylinder.

[0012] In some embodiments of the present invention, the catalyst has a diameter of 0.5 to 2 mm and a height of 1 to 5 mm; preferably, the diameter is 1 mm and the height is 2 mm. Preferably, the diameter of the inner hole is 0.1~0.5 mm, more preferably 0.2 mm.

[0013] The second aspect of this invention discloses a method for preparing the above-mentioned 1,4-butanediol-γ-butyrolactone catalyst for cyclic hydrogen storage, comprising the following steps: (1) Preparation of carrier precursor by coprecipitation method: copper salt solution is mixed with salt solution containing skeleton component, and coprecipitation reaction is carried out in the presence of precipitant to obtain the first suspension; (2) Additive loading and crystal phase control: At least one rare earth additive element is introduced into the first suspension and reacted in the presence of an alkaline precipitant. Then, a silver salt solution is introduced for modification to obtain the modified suspension. (3) Post-processing and molding: The modified suspension is subjected to solid-liquid separation, washing, drying and calcination to obtain catalyst powder, which is then mixed with calcium stearate and molded.

[0014] In some embodiments of the present invention, step (1) specifically includes: Copper salt is dissolved in water to obtain a copper salt solution; precursor salts and surfactants of the framework components are dissolved in water to obtain a framework component solution; the two are mixed to obtain a mixed salt solution; oxalic acid, ammonia, and additives are dissolved in water to obtain a coprecipitant; Under stirring and at 50-65 °C, the coprecipitant was added dropwise to the mixed salt solution, and the pH at the reaction endpoint was controlled to be 7.0-7.5. The mixture was then allowed to mature for 1-6 h to obtain the first suspension. Preferably, the copper salt is copper nitrate; preferably, the concentration of the copper salt solution is 0.5~2 mol / L, more preferably 1 mol / L; Preferably, the precursor salt of the framework component includes cerium ammonium nitrate and at least one of the following components: zinc nitrate, titanium oxysulfate, zirconium oxycarbonate, ammonium heptamolybdate, and aluminum nitrate; preferably, the concentration of cerium ammonium nitrate in the framework component solution is 0.1~0.6 mol / L, more preferably 0.3 mol / L, and the total concentration of other framework component precursor salts is 0.2~0.8 mol / L, more preferably 0.4 mol / L; Preferably, the surfactant is at least one of CTAB, PEG, and PVA; the surfactant concentration in the skeleton component solution is 2-6 wt%, more preferably 4 wt%. Preferably, the additive is 1,4-butanediol or γ-butyrolactone, wherein 1,4-butanediol is used when preparing the dehydrogenation catalyst and γ-butyrolactone is used when preparing the hydrogenation catalyst. Preferably, in the coprecipitant, the concentration of oxalic acid is 0.8~1.6 mol / L, the concentration of ammonia is 1.0~2.0 mol / L, and the content of additives is 5 wt%.

[0015] In some embodiments of the present invention, step (2) specifically includes: A rare earth additive precursor salt solution is added dropwise to the first suspension, while an alkaline precipitant composed of ammonia and ammonium carbonate is added dropwise simultaneously. After the additive solution is completely added, the pH of the system is controlled to be 8.0~9.0 by the alkaline precipitant to obtain the second suspension. The silver salt is dissolved in water and added to the second suspension in one go. The mixture is stirred at 60-80 °C for 3-5 h to obtain the modified suspension. Preferably, the concentration of the silver salt solution is 0.05-0.2 mol / L, more preferably 0.1 mol / L. Preferably, the rare earth additive precursor salt is at least one selected from neodymium nitrate, praseodymium nitrate, yttrium nitrate, cerium ammonium nitrate, and lanthanum nitrate; more preferably, the concentration of the rare earth additive precursor salt in the rare earth additive precursor salt solution is 0.1~0.4 mol / L, and even more preferably 0.2 mol / L; Preferably, in the alkaline precipitant, the concentration of ammonia is 1~3 mol / L and the concentration of ammonium carbonate is 1~3 mol / L; Preferably, the silver salt is silver nitrate.

[0016] In some embodiments of the present invention, in step (3): the drying is performed at 80~130 ℃ for 6~24 h; The roasting is carried out at 350~550 ℃ for 2~5 h.

[0017] The third aspect of the present invention discloses the application of a catalyst in the dehydrogenation of 1,4-butanediol or the hydrogenation of γ-butyrolactone, wherein the catalyst is the above-mentioned catalyst for cyclic hydrogen storage of 1,4-butanediol / γ-butyrolactone, or a catalyst prepared by the above method.

[0018] In some embodiments of the present invention, the application is a cyclic hydrogen storage process between 1,4-butanediol dehydrogenation and γ-butyrolactone; Preferably, before being used in the cyclic hydrogen storage process, the catalyst is subjected to reduction treatment at a temperature of 150°C to 220°C and a pressure of 0.1 MPa to 2.0 MPa for 4 to 8 hours; Preferably, in the selective dehydrogenation step of 1,4-butanediol, the reaction temperature is 160~280 °C, the reaction pressure is 0~0.5 MPa(G), and the liquid hourly space velocity is 0.5~2.5 h⁻¹. -1 The molar ratio of hydrogen alcohols is 10~100; Preferably, in the hydrogenation step of γ-butyrolactone, the reaction temperature is 150~230 °C, the reaction pressure is 1.0~5.0 MPa(G), and the liquid hourly space velocity is 0.5~2 h⁻¹. -1 .

[0019] Compared with the prior art, the present invention has the following beneficial effects: The catalyst provided by this invention completely avoids the use of environmentally harmful elements (such as hexavalent chromium), and has high activity, high selectivity, excellent anti-carbon deposition performance and long-term stability, meeting the actual industrial requirements of BDO / GBL cycle in LOHC system for efficient and stable operation of catalyst under mild reaction conditions.

[0020] In this invention, Cu is the main oligomeric component of the catalyst, and the valence state distribution of Cu is controlled by doping with a small amount of Ag (Cu). 0 / Cu + A strong interaction exists between Cu and Ag, and this synergistic effect effectively inhibits the sintering of active sites during the reaction process, significantly improving the high-temperature stability of the catalyst. The Cu in the catalyst of this invention... + It exhibits superior adsorption capacity for BDO and its key intermediates (such as 2-HTHF), thereby improving the selectivity for BDO dehydrogenation product GBL and GBL hydrogenation product BDO. + Both oxygen vacancies and active oxygen vacancies effectively promote the breaking of O-H and C-H bonds, thus facilitating dehydrogenation / hydrogenation reactions. Furthermore, the CeO2-based framework coupled with rare earth additives (Nd, Pr, Y, Ce, and La) provides a large number of active oxygen vacancies, further enhancing dehydrogenation activity. In addition, calcium stearate, added through a simple mixing process, promotes catalyst formation while neutralizing acidic sites on the catalyst surface, reducing side reactions such as disproportionation and isomerization at the source, improving product selectivity, inhibiting coking, and enhancing catalyst stability.

[0021] Compared to traditional stepwise precipitation processes, the catalyst preparation method of this invention achieves precise customization of component structure and function. This invention employs specific precipitants and precipitation sequences to address the functional requirements of different components. First, a co-precipitant is used to uniformly co-precipitate Cu and framework components; then, an alkaline precipitant is used to further precipitate rare earth additives to optimize the framework and create more oxygen vacancies; finally, oxalate ions in the system are used to precipitate Ag, precisely anchoring it around Cu to build strong interactions. Furthermore, this invention introduces additives in the crucial first precipitation step, effectively improving the catalyst's adsorption characteristics in the reaction system and contributing to the overall activity enhancement. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0023] Example 1 This embodiment discloses the preparation method of the 1,4-butanediol / γ-butyrolactone circulating hydrogen storage catalyst of the present invention. The catalyst composition of this embodiment is: CuO 58 wt%, AgO 1.0 wt%, CeO2 20 wt%, ZnO 10 wt%, TiO2 6 wt%, Nd2O3 3 wt%, and calcium stearate 2.0 wt%.

[0024] Its preparation method includes the following steps: S1. Preparation of the carrier precursor: Copper nitrate was dissolved in water to prepare a copper salt solution with a concentration of 1 mol / L; zinc nitrate, cerium ammonium nitrate, and titanium oxysulfate were dissolved in deionized water, and surfactant CTAB was added. The mixture was stirred thoroughly to obtain a framework component solution; the concentrations of zinc nitrate, cerium ammonium nitrate, titanium oxysulfate, and CTAB in the framework component solution were 0.3 mol / L, 0.3 mol / L, 0.1 mol / L, and 4 wt%, respectively; the copper salt solution was mixed with the framework component solution to obtain a mixed salt solution; Oxalic acid, ammonia, and 1,4-butanediol were mixed in a specific ratio (oxalic acid concentration: 1.2 mol / L, ammonia concentration: 1.5 mol / L, and 1,4-butanediol content: 5 wt%) and dissolved in deionized water to obtain a coprecipitant. Under reaction conditions of 60℃ and stirring speed of 300 rpm, the coprecipitant was slowly added dropwise to the mixed salt solution. The final pH of the reaction was controlled at 7.2. The addition was then stopped, and stirring continued for 3 hours to obtain the first suspension.

[0025] S2. Additive Loading and Crystal Phase Control: Neodymium nitrate was dissolved in deionized water to obtain a 0.2 mol / L rare earth additive solution; ammonia and ammonium carbonate were mixed in a 1:1 molar ratio to prepare an alkaline precipitant (both at a concentration of 2 mol / L). Under continuous stirring, the rare earth additive solution and the alkaline precipitant were simultaneously added dropwise to the first suspension. After the rare earth additive solution was completely added, the alkaline precipitant was added dropwise, controlling the pH of the system to 8.5, to obtain the second suspension. Silver nitrate was dissolved in water and added to the second suspension in one go. The mixture was stirred at 70°C for 4 hours to obtain the modified suspension.

[0026] S3. The modified suspension was filtered and washed repeatedly with ethanol until neutral. The filter cake was dried at 100°C for 12 hours and calcined at 500°C for 3 hours to obtain catalyst powder. Calcium stearate was added to the powder, and after mixing evenly, it was pressed into a tablet to obtain a three-porous cylindrical catalyst with an external diameter of Φ5×5 mm and an internal pore diameter of 1.5 mm.

[0027] Example 2 Example 2 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, Example 2 changes the catalyst composition to: CuO 75 wt%, AgO 0.8 wt%, CeO2 15 wt%, ZrO2 5 wt%, Y2O3 2 wt%, and calcium stearate 2.2 wt%.

[0028] The preparation method differs from that in Example 1 in that: In step S1, the precursors zinc nitrate and titanium oxysulfate were replaced with zirconium oxycarbonate, and the additive 1,4-butanediol was replaced with γ-butyrolactone. In step S2, the rare earth auxiliary precursor neodymium nitrate was replaced with yttrium nitrate, and all other conditions remained the same.

[0029] Example 3 Example 3 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone circulating hydrogen storage catalyst of the present invention. Compared with Example 1, the catalyst composition of Example 3 is changed to: CuO 55 wt%, AgO 1.2 wt%, CeO2 33 wt%, Al2O3 5 wt%, La2O3 2 wt%, and calcium stearate 3.8 wt%.

[0030] The preparation method differs from that in Example 1 in that: the zinc sulfate and titanium oxysulfate precursors in step S1 are replaced with aluminum nitrate; the neodymium nitrate precursor in step S2 is replaced with lanthanum nitrate; and all other conditions are the same.

[0031] Example 4 Example 4 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, in step S2 of the preparation method of Example 4, the rare earth additive is a mixture of neodymium nitrate, praseodymium nitrate and yttrium nitrate in a metal oxide mass ratio of 1:1:1, and the other conditions are the same.

[0032] Example 5 Example 5 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, Example 5 changes the catalyst composition to: CuO 58 wt%, AgO 1.0 wt%, CeO2 25 wt%, ZrO2 12 wt%, Nd2O3 2 wt%, and calcium stearate 2.0 wt%.

[0033] The preparation method of the catalyst in Example 5 differs from that in Example 1 in that the precursors zinc nitrate and titanium oxysulfate in step S1 are replaced with zirconium oxycarbonate and added together with cerium ammonium nitrate; all other conditions are the same.

[0034] Example 6 Example 6 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, the difference is that the amount of silver nitrate added in step S2 is adjusted so that the AgO content in the prepared catalyst is 0.5 wt%; all other conditions are the same.

[0035] Example 7 Example 7 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, the difference is that the amount of calcium stearate added in step S3 is adjusted to 4.5 wt%.

[0036] Example 8 Example 8 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone circulating hydrogen storage catalyst of the present invention. Compared with Example 1, the difference is that the calcination temperature in step S3 is 350°C and the calcination time is 5 hours.

[0037] Example 9 Example 9 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, the difference is that the calcination temperature in step S3 is 550°C and the calcination time is 2 hours.

[0038] Example 10 Example 10 discloses the preparation method of the 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst of the present invention. Compared with Example 1, the difference is that 1,4-butanediol is not added when preparing the co-precipitant in step S1.

[0039] Comparative Example 1 A comparative catalyst was prepared according to Example 1 of CN116173977A. Its composition was: CuO 28.4 wt%, ZnO 26.3 wt%, ZrO2 26.3 wt%, TiO2 10.5 wt%, CrO3 3.2 wt%, Ce2O3 5.3 wt%. This catalyst was prepared by a stepwise co-precipitation method, using chromic anhydride (CrO3) as the chromium source.

[0040] Comparative Example 2 The catalyst of Comparative Example 2 has the same composition and preparation method as that of Example 1, except that silver nitrate is not added, that is, the catalyst does not contain AgO component.

[0041] Comparative Example 3 The catalyst of Comparative Example 3 has the same composition and preparation method as that of Example 1, except that neodymium nitrate is not added, that is, the catalyst does not contain rare earth additive Nd2O3.

[0042] Comparative Example 4 The catalyst in Comparative Example 4 has the same composition as that in Example 1. The difference in its preparation method compared to Example 1 is that a one-step co-precipitation method is used. All metal salt solutions (copper nitrate, zinc nitrate, titanium oxysulfate, cerium ammonium nitrate, neodymium nitrate, and silver nitrate) are mixed to obtain a total salt solution, which is then precipitated in one step using a single precipitant (a mixture of oxalic acid and ammonia). In this comparative example, the oxalic acid concentration is 1.2 mol / L and the ammonia concentration is 1.5 mol / L, the same as in Example 1.

[0043] Experimental Example 1 This experimental example discloses performance evaluation tests of the catalysts prepared in Examples 1-10 and Comparative Examples 1-4. The catalyst performance evaluation method is as follows: 1. Dehydrogenation reaction (BDO→GBL): The shaped catalyst was packed into a fixed-bed reactor and reduced at 200°C for 6 hours under a H2 atmosphere. After reduction, the conditions were switched to dehydrogenation reaction conditions: reaction temperature 200°C, reaction pressure 0.1 MPa(G), and 1,4-butanediol liquid hourly space velocity (LHSV) 1.0 h⁻¹. -1 ¹, Hydrogen alcohol molar ratio 20:1. After the reaction stabilized, the product composition was analyzed by gas chromatography, and the BDO conversion and GBL selectivity were calculated.

[0044] 2. Hydrogenation reaction (GBL→BDO): The catalytic reduction steps are the same as the dehydrogenation reaction. After reduction, the hydrogenation reaction conditions are switched to: reaction temperature 190℃, reaction pressure 3.0 MPa(G), and γ-butyrolactone liquid hourly space velocity (LHSV) 1.0 h⁻¹. -1 The hydrogen-ester molar ratio was 50:1. After the reaction stabilized, the GBL conversion and BDO selectivity were calculated.

[0045] 3. Stability test: The catalyst was continuously operated for 500 hours under dehydrogenation reaction conditions to examine its activity and stability.

[0046] The catalysts obtained in Examples 1-10 and Comparative Examples 1-4 were evaluated for performance, and the results are shown in the table below.

[0047] Table 1 Performance Evaluation Results of Each Catalyst

[0048] As shown in the table above, the catalysts of this invention (Examples 1-10) exhibit high activity, high selectivity, and excellent stability in the dehydrogenation of 1,4-butanediol and the hydrogenation of γ-butyrolactone. The BDO dehydrogenation conversion rates of all examples are above 98.5%, and the GBL selectivity also exceeds 98.3%. Furthermore, they demonstrate excellent stability during long-term operation: after 500 hours of reaction, the decrease in BDO dehydrogenation conversion rate is controlled within 4%, with Example 7 being particularly outstanding due to its lower than 1% decay rate and minimal carbon buildup.

[0049] Compared to the existing chromium-containing catalyst represented by Comparative Example 1, the catalyst of the present invention completely avoids the use of chromium while achieving the same or even better activity and selectivity, demonstrating significant environmental advantages.

[0050] Further comparison with Comparative Examples 2-4 shows that Comparative Example 2, lacking the AgO component, suffers from severely degraded catalyst stability, with a conversion rate decrease exceeding 8%, indicating that AgO is crucial for maintaining the long-term stability of the catalyst. Comparative Example 3, without rare earth additives, exhibits a decline in all performance indicators, confirming the important role of rare earth additives in enhancing catalytic activity and selectivity. Furthermore, Comparative Example 4, prepared using a one-step co-precipitation method, shows a significant reduction in catalytic activity and is prone to sintering, resulting in a sharp decrease in stability. This, conversely, confirms that a stepwise precipitation process is essential for forming catalysts with ideal structures and performance.

[0051] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0052] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects described in this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A catalyst for cyclic hydrogen storage using 1,4-butanediol / γ-butyrolactone, characterized in that, The catalyst comprises a bimetallic active ingredient, a framework component, rare earth additives, and calcium stearate; The bimetallic active components are CuO and AgO; The skeletal components include CeO2 and at least one of the following oxides: ZnO, TiO2, ZrO2, MoO3, and Al2O3. The rare earth additive is at least one of Nd, Pr, Y, Ce, and La; Based on the total mass of the catalyst, the CuO content is 55~80 wt%, the AgO content is 0.5~1.5 wt%, the total content of the framework components is 15~42 wt%, of which the CeO2 content is 10~38 wt%, the rare earth auxiliary oxide content is 1~5 wt%, and the calcium stearate content is 1.5~4.5 wt%.

2. The 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst according to claim 1, characterized in that, Based on the total mass of the catalyst, the CuO content is 55–75 wt%, the AgO content is 0.5–1.2 wt%, the total content of the framework components is 20–40 wt%, of which the CeO2 content is 15–35 wt%, the rare earth auxiliary oxide content is 2–3 wt%, and the calcium stearate content is 2.5–4.5 wt%. Preferably, based on the total mass of the catalyst, its composition is CuO 58 wt%, AgO 1.0 wt%, CeO2 20 wt%, ZnO 10 wt%, TiO2 6 wt%, Nd2O3 3 wt%, and calcium stearate 2.0 wt%.

3. The catalyst for cyclic hydrogen storage of 1,4-butanediol / γ-butyrolactone according to claim 1, characterized in that, The catalyst has a porous cylindrical shape; preferably a three-porous cylindrical shape.

4. The 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst according to claim 3, characterized in that, The catalyst has a diameter of 0.5-2 mm and a height of 1-5 mm; preferably, the diameter is 1 mm and the height is 2 mm. Preferably, the diameter of the inner hole is 0.1~0.5 mm, more preferably 0.2 mm.

5. A method for preparing a 1,4-butanediol-γ-butyrolactone cyclic hydrogen storage catalyst according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of carrier precursor by coprecipitation method: copper salt solution is mixed with salt solution containing skeleton component, and coprecipitation reaction is carried out in the presence of precipitant to obtain the first suspension; (2) Additive loading and crystal phase control: At least one rare earth additive element is introduced into the first suspension and reacted in the presence of an alkaline precipitant. Then, a silver salt solution is introduced for modification to obtain the modified suspension. (3) Post-processing and molding: The modified suspension is subjected to solid-liquid separation, washing, drying and calcination to obtain catalyst powder, which is then mixed with calcium stearate and molded.

6. The method for preparing a 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst according to claim 5, characterized in that, Step (1) specifically includes: Copper salt is dissolved in water to obtain a copper salt solution; precursor salts and surfactants of the framework components are dissolved in water to obtain a framework component solution; the two are mixed to obtain a mixed salt solution; oxalic acid, ammonia, and additives are dissolved in water to obtain a coprecipitant; Under stirring and at 50-65 °C, the coprecipitant was added dropwise to the mixed salt solution, and the pH at the reaction endpoint was controlled to be 7.0-7.

5. The mixture was then allowed to mature for 1-6 h to obtain the first suspension. Preferably, the copper salt is copper nitrate; preferably, the concentration of the copper salt solution is 0.5~2 mol / L, more preferably 1 mol / L; Preferably, the precursor salt of the framework component includes cerium ammonium nitrate and at least one of the following components: zinc nitrate, titanium oxysulfate, zirconium oxycarbonate, ammonium heptamolybdate, and aluminum nitrate; preferably, the concentration of cerium ammonium nitrate in the framework component solution is 0.1~0.6 mol / L, more preferably 0.3 mol / L; the total concentration of other framework component precursor salts is preferably 0.2~0.8 mol / L, more preferably 0.4 mol / L. Preferably, the surfactant is at least one of CTAB, PEG, and PVA; the surfactant concentration in the skeleton component solution is 2-6 wt%, more preferably 4 wt%. Preferably, the additive is 1,4-butanediol or γ-butyrolactone, wherein 1,4-butanediol is used when preparing the dehydrogenation catalyst and γ-butyrolactone is used when preparing the hydrogenation catalyst. Preferably, in the coprecipitant, the concentration of oxalic acid is 0.8~1.6 mol / L, the concentration of ammonia is 1.0~2.0 mol / L, and the content of additives is 5 wt%.

7. The method for preparing a 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst according to claim 5, characterized in that, Step (2) specifically includes: A rare earth additive precursor salt solution is added dropwise to the first suspension, while an alkaline precipitant composed of ammonia and ammonium carbonate is added dropwise simultaneously. After the rare earth additive precursor salt solution has been added, the pH of the system is controlled to be 8.0~9.0 by the alkaline precipitant to obtain the second suspension. The silver salt is dissolved in water and added to the second suspension in one go. The mixture is stirred at 60-80 °C for 3-5 h to obtain the modified suspension. Preferably, the concentration of the silver salt solution is 0.05-0.2 mol / L, more preferably 0.1 mol / L. Preferably, the rare earth additive precursor salt is at least one selected from neodymium nitrate, praseodymium nitrate, yttrium nitrate, cerium ammonium nitrate, and lanthanum nitrate; more preferably, the concentration of the rare earth additive precursor salt in the rare earth additive precursor salt solution is 0.1~0.4 mol / L, and even more preferably 0.2 mol / L; Preferably, in the alkaline precipitant, the concentration of ammonia is 1~3 mol / L and the concentration of ammonium carbonate is 1~3 mol / L; Preferably, the silver salt is silver nitrate.

8. The method for preparing a 1,4-butanediol / γ-butyrolactone cyclic hydrogen storage catalyst according to claim 5, characterized in that, In step (3): the drying process is carried out at 80~130 ℃ for 6~24 h; The roasting is carried out at 350~550 ℃ for 2~5 h.

9. The application of a catalyst in the dehydrogenation of 1,4-butanediol or the hydrogenation of γ-butyrolactone, characterized in that, The catalyst is the catalyst according to any one of claims 1-4, or a catalyst prepared by the method according to any one of claims 5-8.

10. The application as described in claim 9, characterized in that, The application is a cyclic hydrogen storage process between 1,4-butanediol dehydrogenation and γ-butyrolactone. Preferably, before being used in the cyclic hydrogen storage process, the catalyst is subjected to reduction treatment at a temperature of 150°C to 220°C and a pressure of 0.1 MPa to 2.0 MPa for 4 to 8 hours. Preferably, in the selective dehydrogenation step of 1,4-butanediol, the reaction temperature is 160–280 °C, the reaction pressure is 0–0.5 MPa(G), and the liquid hourly space velocity is 0.5–2.5 h⁻¹. -1 The molar ratio of hydrogen alcohols is 10~100; Preferably, in the hydrogenation step of γ-butyrolactone, the reaction temperature is 150~230 °C, the reaction pressure is 1.0~5.0 MPa(G), and the liquid hourly space velocity is 0.5~2 h⁻¹. -1 .

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