Composite carrier dehydrogenation catalyst for preparing gamma-butyrolactone through dehydrogenation of 1, 4-butanediol as well as preparation method and application of composite carrier dehydrogenation catalyst

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a composite carrier dehydrogenation catalyst for preparing gamma-butyrolactone through dehydrogenation of 1, 4-butanediol as well as a preparation method and application of the composite carrier dehydrogenation catalyst. According to the composite carrier dehydrogenation catalyst disclosed by the invention, a Y-type molecular sieve / gamma-Al2O3 is used as a composite carrier, and an active component copper oxide is loaded on the composite carrier; wherein the mass ratio of the Y-type molecular sieve to the gamma-Al2O3 is (1-2): 1, the copper element content is 10%-20% according to the weight ratio of the composite carrier, and the zinc element content is 6%-10% according to the weight ratio of the composite carrier. By adopting a composite carrier structure, the dispersity and stability of active metals Cu and Zn are effectively enhanced. The composite carrier dehydrogenation catalyst prepared by the preparation method provided by the invention has the advantages of high catalytic activity, high selectivity and high stability.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a composite carrier dehydrogenation catalyst for preparing gamma-butyrolactone by dehydrogenating 1,4-butanediol, and a preparation method and application thereof. Background Art

[0002] γ-Butyrolactone is a colorless, oily liquid with a unique aromatic smell. It is miscible with water in any proportion and is easily soluble in a variety of organic solvents such as methanol, ethanol, acetone, ether and benzene. As an important chemical raw material and pharmaceutical intermediate, γ-butyrolactone is widely used in many fields such as petrochemicals, medicines, dyes, pesticides and fine chemicals. In addition, due to its excellent solubility, it has become a high-quality solvent with huge demand in industry. The rapid development of industries such as fine chemicals and biodegradable plastics has driven the continuous growth of demand for γ-butyrolactone. Its main synthesis pathways include furfural method, maleic anhydride hydrogenation method and 1,4-butanediol dehydrogenation method. 1,4-butanediol dehydrogenation method has become the mainstream method for industrial production of γ-butyrolactone due to its advantages in simple product components and easy separation. The core of this process lies in the development and application of high-performance catalysts. However, the copper-based catalysts widely used in industry at this stage still have problems such as low γ-butyrolactone yield and chromium pollution. Therefore, in-depth research on the relationship between the composition, structure and performance of the catalyst is of great theoretical and practical significance for developing better catalysts, optimizing the γ-butyrolactone production process and improving the yield.

[0003] Chinese patent CN116272984A discloses a catalyst for catalyzing the dehydrogenation of 1,4-butanediol to prepare γ-butyrolactone, using a mixture of a carbon carrier and a metal oxide carrier as a catalyst carrier, adding silver nitrate to obtain a catalyst loaded with silver ions. The catalyst achieves a 95% conversion rate of 1,4-butanediol and a 95% selectivity for γ-butyrolactone. However, under long-term high temperature conditions, the active components still aggregate or lose, resulting in catalyst deactivation and reduced catalytic efficiency.

[0004] Therefore, how to develop a catalyst with low production cost, simple process operation and easy large-scale application while meeting the requirements of high stability and high catalytic activity has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In view of the problems and shortcomings in the prior art, the purpose of the present invention is to provide a composite support dehydrogenation catalyst and a preparation method thereof, which are applied to the preparation of γ-butyrolactone by dehydrogenation of 1,4-butanediol. The composite support dehydrogenation catalyst prepared by the preparation method provided by the present invention has high catalytic activity, high selectivity and high stability.

[0006] Based on the above purpose, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a composite support dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone, using Y-type molecular sieve / γ-Al2O3 as a composite support and loaded with an active component of copper oxide; wherein the mass ratio of the Y-type molecular sieve to γ-Al2O3 is (1-2):1, and the copper element content is 10% to 20% based on the weight ratio of the composite support.

[0008] Furthermore, the composite carrier dehydrogenation catalyst also includes zinc oxide as an auxiliary agent, and the zinc content is 6% to 10% based on the weight ratio of the composite carrier.

[0009] Furthermore, the composite carrier dehydrogenation catalyst also includes pseudo-boehmite, sesbania powder and PEG20000.

[0010] Furthermore, the Y-type molecular sieve is a microporous Y-type molecular sieve.

[0011] Preferably, the mass ratio of the Y-type molecular sieve to γ-Al2O3 is 1:1.

[0012] Preferably, the copper content is 15% based on the weight ratio of the composite carrier.

[0013] Preferably, the zinc content is 8% based on the weight ratio of the composite carrier.

[0014] The second aspect of the present invention provides a method for preparing a composite supported dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone as described in the first aspect, comprising the following steps:

[0015] S1: dissolving aluminum hydroxide and sodium hydroxide in water, heating for reaction for 2 hours and then cooling to room temperature, adding Y-type molecular sieve after adjusting the pH, and then drying and primary calcination are performed in sequence to obtain a composite carrier Y-type molecular sieve / γ-Al2O3;

[0016] S2: dissolving a divalent copper salt in water, adding the composite carrier described in S1 to obtain a mixed system, loading the divalent copper salt on the composite carrier by an impregnation method, and then drying and performing a second calcination treatment to obtain a composite carrier dehydrogenation catalyst.

[0017] Furthermore, the divalent copper salt is any one of copper sulfate, copper chloride and copper nitrate; the mass ratio of the divalent copper salt to the composite carrier is (0.35-0.8):1.

[0018] Furthermore, the mixed system also includes a divalent zinc salt; the divalent zinc salt is zinc nitrate or zinc sulfate; the mass ratio of the divalent zinc salt to the composite carrier is (0.25-0.5):1.

[0019] Furthermore, the mass ratio of the Y-type molecular sieve to γ-Al2O3 in the composite carrier in step S1 is (1-2):1.

[0020] Furthermore, in step S2, the immersion temperature is room temperature, and the immersion time is 10 to 12 hours.

[0021] Furthermore, the temperature of the first calcination is 520-580°C, and the time is 5-6 hours; the temperature of the second calcination is 520-580°C, and the time is 5-6 hours.

[0022] Furthermore, the method further comprises a molding step: mixing the composite carrier dehydrogenation catalyst obtained in step S2 with pseudo-boehmite, sesbania powder and PEG20000, kneading, extruding, air-drying, drying and third calcining.

[0023] Furthermore, the specific steps of forming the composite carrier dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone are as follows:

[0024] S1: uniformly mixing the composite carrier dehydrogenation catalyst, pseudo-boehmite, sesbania powder and PEG20000 to obtain a mixed material;

[0025] S2: The mixed material, peptizing agent and water described in S1 are mixed and kneaded, extruded and shaped, air-dried at room temperature, dried, and calcined for the third time to obtain a shaped composite carrier dehydrogenation catalyst.

[0026] Preferably, in step S1, the mass ratio of the composite carrier dehydrogenation catalyst, pseudo-boehmite, sesbania powder and PEG20000 is 30:15:1:2.

[0027] Preferably, the peptizing agent in step S2 is dilute nitric acid with a mass content of 10%.

[0028] Preferably, the mass ratio of the mixed material to the peptizing agent is 5:4.

[0029] Preferably, the temperature of the third calcination in step S2 is 500-550° C., and the calcination time is 4-5 hours.

[0030] The third aspect of the present invention provides the use of the composite support dehydrogenation catalyst described in the first aspect in the dehydrogenation of 1,4-butanediol to prepare γ-butyrolactone, comprising the following steps:

[0031] S1: loading the composite support dehydrogenation catalyst into a fixed bed reactor and introducing circulating hydrogen for reduction activation;

[0032] S2: After the reduction activation is completed, the circulating hydrogen and the vaporized raw material liquid 1,4-butanediol are introduced into the fixed bed reactor to carry out a dehydrogenation reaction.

[0033] Preferably, the reduction activation conditions are: reduction temperature of 200-280°C, reduction time of 4-8h, reduction pressure of normal pressure, and circulating hydrogen space velocity of 500-2000h -1 .

[0034] Preferably, the conditions of the dehydrogenation reaction are: reaction temperature 200-240°C, reaction pressure 70kPa-80kPa, feed space velocity of raw material liquid 1,4-butanediol 1.0-2.5h -1 , the molar ratio of circulating hydrogen to 1,4-butanediol is (3~9):1.

[0035] The mechanism of the composite support dehydrogenation catalyst of the present invention is as follows:

[0036] In the composite support dehydrogenation catalyst, the composite between Y-type molecular sieve and γ-Al2O3 can optimize the physical and chemical properties of the catalyst. Y-type molecular sieve provides a regular microporous structure, and its microporous channel structure can effectively disperse the active sites of Cu and Zn, enhancing the Cu o Synergistic effect between Cu and ZnO. γ-Al2O3 has excellent thermal stability and mechanical strength, which can improve the overall structural stability and sintering resistance of the catalyst. The surface hydroxyl functional groups on γ-Al2O3 contribute to the uniform distribution of Cu and ZnO active sites, and can regulate the electron density of the active center, thereby improving the dehydrogenation performance and service life of the catalyst. The combination of the two maximizes the synergistic effect of Cu and ZnO, thereby improving the overall performance of the catalyst.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The composite supported catalyst of the present invention significantly improves the purity and yield of the target product compared with the conventional catalyst. The Y-type molecular sieve of the present invention has a regular pore structure and suitable acid sites, which can effectively adjust the acidity and alkalinity of the catalyst during the reaction, thereby inhibiting the formation of side reactions (such as dehydration side reactions) and byproducts (such as tetrahydrofuran, unsaturated hydrocarbon compounds and other impurities); in addition, the presence of ZnO can effectively reduce the surface acidity of the catalyst, thereby inhibiting the occurrence of dehydration side reactions, reducing the formation of byproducts (such as tetrahydrofuran and unsaturated olefin compounds), and improving the selectivity and yield of γ-butyrolactone.

[0039] (2) In the composite support dehydrogenation catalyst of the present invention, Cu exists in the form of CuO, which can be reduced to metallic copper (Cu) during the reaction. o ), as the main active site. Metallic copper can effectively adsorb and dissociate molecular hydrogen, promote the desorption and transfer of hydrogen, and thus significantly improve the dehydrogenation activity of the catalyst. oIt can also promote the breaking of CH bonds in alcohol molecules, allowing them to undergo a smooth dehydrogenation reaction to generate the target product γ-butyrolactone. Zn exists in the form of ZnO, which has good electron acceptor properties and can adjust the electron distribution on the Cu surface, thereby improving the Cu o At the same time, the interaction between ZnO and Cu can form a Cu-Zn interface, which can further enhance the dehydrogenation ability of the active center. o The present invention adopts a composite carrier structure to effectively enhance the dispersibility and stability of active metals Cu and Zn, so that it can still show excellent dehydrogenation activity and high γ-butyrolactone selectivity at low content (Cu content is less than 20%).

[0040] (3) The present invention can maintain high catalytic activity and stability under long-term reaction conditions. Since the active sites of Cu and Zn in the catalyst are wrapped and isolated by the pores and surface functional groups of the Y-type molecular sieve and the γ-Al2O3 carrier, the agglomeration and sintering of the metal active centers are effectively prevented, thereby greatly improving the structural stability and anti-sintering ability of the catalyst under high temperature and complex reaction conditions.

[0041] (4) The present invention does not contain Cr and rare earth metal elements, is environmentally friendly, and has significant economic benefits. The catalyst formula of the present invention does not use toxic and harmful Cr elements and expensive rare earth metal elements, which not only reduces the potential pollution of the catalyst to the environment, but also significantly reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Evaluation of the stability of the composite support dehydrogenation catalyst of the present invention (1,4-butanediol conversion rate);

[0043] Figure 2 This is an evaluation of the stability of the composite support dehydrogenation catalyst of the present invention (γ-butyrolactone selectivity). DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through embodiments in combination with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] (I) Investigating the effect of different copper contents in the catalyst on the performance of the dehydrogenation catalyst

[0046] Example 1

[0047] A composite support dehydrogenation catalyst for preparing γ-butyrolactone from 1,4-butanediol, the catalyst comprising a Y-type molecular sieve / γ-Al2O3 composite support and an active component loaded on the composite support. The active component is CuO, and the mass ratio of the Y-type molecular sieve to γ-Al2O3 in the composite support is 1:1. The mass content of the copper element is 10% based on the weight ratio of the composite support.

[0048] The method for preparing the composite carrier dehydrogenation catalyst for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol comprises the following steps:

[0049] (1) 15.3 g of aluminum hydroxide, 15.3 g of sodium hydroxide and deionized water were mixed under stirring, reacted for 2 h under boiling conditions to obtain a sodium aluminate solution, and cooled to room temperature; then dilute nitric acid was added to adjust the pH value to 7.5, maintained at 50°C for 0.5 h, and filtered while hot to obtain an aluminum hydroxide gel; dilute ammonia water was added to adjust the pH value to 8.0, stirred at 45°C for 5 min after condensation, filtered and washed 3 times, then deionized water and 10 g of microporous Y-type molecular sieve were added, mixed thoroughly, and then allowed to stand at room temperature for 12 h, dried in an oven at 110°C for 12 h, and finally calcined at 580°C in an air atmosphere for 5 h to obtain a composite carrier.

[0050] (2) Dissolve 3.8 g of Cu(NO3)2·3H2O in 20 mL of deionized water. After complete dissolution, add 10 g of the composite carrier obtained in step (1), stir thoroughly, let stand for 12 h, dry in an oven at 110°C for 12 h, then grind, and then calcine at 580°C in an air atmosphere for 5 h, grind, and press into tablets with a mesh size of 20 to 80 to obtain a composite carrier dehydrogenation catalyst A.

[0051] Example 2

[0052] A composite support dehydrogenation catalyst for preparing γ-butyrolactone from 1,4-butanediol, the catalyst comprising a Y-type molecular sieve / γ-Al2O3 composite support and an active component loaded on the composite support. The active component is CuO, and the mass ratio of the Y-type molecular sieve to γ-Al2O3 in the composite support is 1:1. The mass content of the copper element is 15% based on the weight ratio of the composite support.

[0053] The method for preparing the composite carrier dehydrogenation catalyst for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol comprises the following steps:

[0054] (1) 15.3 g of aluminum hydroxide, 15.3 g of sodium hydroxide and deionized water were mixed under stirring, reacted for 2 h under boiling conditions to obtain a sodium aluminate solution, and cooled to room temperature; then dilute nitric acid was added to adjust the pH value to 7.5, maintained at 50°C for 0.5 h, and filtered while hot to obtain an aluminum hydroxide gel; dilute ammonia water was added to adjust the pH value to 8.0, stirred at 45°C for 5 min after condensation, filtered and washed 3 times, then deionized water and 10 g of microporous Y-type molecular sieve were added, mixed thoroughly, and then allowed to stand at room temperature for 12 h, dried in an oven at 110°C for 12 h, and finally calcined at 580°C in an air atmosphere for 5 h to obtain a composite carrier.

[0055] (2) Dissolve 5.7 g of Cu(NO3)2·3H2O in 20 mL of deionized water. After complete dissolution, add 10 g of the composite support obtained in step (1), stir thoroughly, let stand for 12 h, dry in an oven at 110°C for 12 h, grind, and then calcine at 580°C in an air atmosphere for 5 h. Grind and press into tablets with a mesh size of 20 to 80 to obtain a composite support dehydrogenation catalyst B.

[0056] Example 3

[0057] A composite support dehydrogenation catalyst for preparing γ-butyrolactone from 1,4-butanediol, the catalyst comprising a Y-type molecular sieve / γ-Al2O3 composite support and an active component loaded on the composite support. The active component is CuO, and the mass ratio of the Y-type molecular sieve to γ-Al2O3 in the composite support is 1:1. The mass content of the copper element is 20% based on the weight ratio of the composite support.

[0058] The method for preparing the composite carrier dehydrogenation catalyst for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol comprises the following steps:

[0059] (1) 15.3 g of aluminum hydroxide, 15.3 g of sodium hydroxide and deionized water were mixed under stirring, reacted for 2 h under boiling conditions to obtain a sodium aluminate solution, and cooled to room temperature; then dilute nitric acid was added to adjust the pH value to 7.5, maintained at 50°C for 0.5 h, and filtered while hot to obtain an aluminum hydroxide gel; dilute ammonia water was added to adjust the pH value to 8.0, stirred at 45°C for 5 min after condensation, filtered and washed 3 times, then deionized water and 10 g of microporous Y-type molecular sieve were added, mixed thoroughly, and then allowed to stand at room temperature for 12 h, dried in an oven at 110°C for 12 h, and finally calcined at 580°C in an air atmosphere for 5 h to obtain a composite carrier.

[0060] (2) Dissolve 7.6 g of Cu(NO3)2·3H2O in 20 mL of deionized water. After complete dissolution, add 10 g of the composite carrier obtained in step (1), stir thoroughly, let stand for 12 h, dry in an oven at 110°C for 12 h, grind, and then calcine at 580°C in an air atmosphere for 5 h. Grind and press into tablets with a mesh size of 20 to 80 to obtain a composite carrier dehydrogenation catalyst C.

[0061] The performance test of the composite support dehydrogenation catalyst prepared in Examples 1 to 3 was carried out: 1.5g of composite support dehydrogenation catalyst A, B and C were respectively loaded into a fixed bed reactor, and reduction activation was carried out in a pressure of 50kPa and a hydrogen atmosphere, with 120°C as the starting temperature, and gradually increased to 220°C at 10°C / min, and the hydrogen flow rate was controlled at about 80mL / min. After the reduction activation was completed, the raw material was pumped into the vaporizer by a metering pump, and hydrogen and vaporized raw material liquid 1,4-butanediol were passed into the fixed bed reactor, and the molar ratio of hydrogen to 1,4-butanediol was 6:1, and a dehydrogenation reaction was carried out. After reacting for 2h, the reactants were received after cooling, and the crude product was analyzed by gas chromatograph GC9790Plus, and the 1,4-butanediol conversion rate and γ-butyrolactone selectivity of the catalytic reaction were calculated. The specific results are shown in Table 1.

[0062] Table 1 Effect of different copper contents of catalyst on the performance of dehydrogenation catalyst

[0063]

[0064] CuO can be reduced to metallic copper (Cu o ), as the main active site. Metallic copper can effectively adsorb and dissociate molecular hydrogen, promote the desorption and transfer of hydrogen, and thus significantly improve the dehydrogenation activity of the catalyst. o It can also promote the breaking of CH bonds in alcohol molecules, allowing them to undergo a smooth dehydrogenation reaction to generate the target product γ-butyrolactone. As can be seen from Table 1, with the increase in the copper content of the active component in the composite support dehydrogenation catalyst, the conversion of 1,4-butanediol first increases and then decreases, and the selectivity of γ-butyrolactone also first increases and then decreases. This is because the excess copper causes the active sites of the catalyst to be overly saturated or unevenly distributed, reducing the catalytic effect.

[0065] (II) Investigating the effect of different zinc contents in the catalyst on the performance of the dehydrogenation catalyst

[0066] Example 4

[0067] A composite support dehydrogenation catalyst for preparing γ-butyrolactone from 1,4-butanediol, the catalyst comprising a Y-type molecular sieve / γ-Al2O3 composite support, an active component loaded on the composite support, and an auxiliary agent. The active component is CuO, the auxiliary agent is ZnO, and the mass ratio of the Y-type molecular sieve and γ-Al2O3 in the composite support is 1:1. The mass content of the copper element is 15% and the mass content of the zinc element is 6% based on the weight ratio of the composite support.

[0068] The method for preparing the composite carrier dehydrogenation catalyst for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol comprises the following steps:

[0069] (1) 15.3 g of aluminum hydroxide, 15.3 g of sodium hydroxide and deionized water were mixed under stirring, reacted for 2 h under boiling conditions to obtain a sodium aluminate solution, and cooled to room temperature; then dilute nitric acid was added to adjust the pH value to 7.5, maintained at 50°C for 0.5 h, and filtered while hot to obtain an aluminum hydroxide gel; dilute ammonia water was added to adjust the pH value to 8.0, stirred at 45°C for 5 min after condensation, filtered and washed 3 times, then deionized water and 10 g of microporous Y-type molecular sieve were added, mixed thoroughly, and then allowed to stand at room temperature for 12 h, dried in an oven at 110°C for 12 h, and finally calcined at 580°C in an air atmosphere for 5 h to obtain a composite carrier.

[0070] (2) Dissolve 5.7 g of Cu(NO3)2·3H2O and 2.8 g of Zn(NO3)2·6H2O in 20 mL of deionized water. After complete dissolution, add 10 g of the composite support obtained in step (1). After sufficient stirring, let stand for 12 h, dry in an oven at 110°C for 12 h, and then grind. Thereafter, calcine at 580°C in an air atmosphere for 5 h, grind, and press into tablets with a mesh size of 20 to 80 to obtain a composite support dehydrogenation catalyst D.

[0071] Example 5

[0072] A composite support dehydrogenation catalyst for preparing γ-butyrolactone from 1,4-butanediol, the catalyst comprising a Y-type molecular sieve / γ-Al2O3 composite support, an active component loaded on the composite support, and an auxiliary agent. The active component is CuO, the auxiliary agent is ZnO, and the mass ratio of the Y-type molecular sieve and γ-Al2O3 in the composite support is 1:1. The mass content of the copper element is 15% and the mass content of the zinc element is 8% based on the weight ratio of the composite support.

[0073] The method for preparing the catalyst for catalyzing the dehydrogenation of 1,4-butanediol to prepare γ-butyrolactone comprises the following steps:

[0074] (1) 15.3 g of aluminum hydroxide, 15.3 g of sodium hydroxide and deionized water were mixed under stirring, reacted for 2 h under boiling conditions to obtain a sodium aluminate solution, and cooled to room temperature; then dilute nitric acid was added to adjust the pH value to 7.5, maintained at 50°C for 0.5 h, and filtered while hot to obtain an aluminum hydroxide gel; dilute ammonia water was added to adjust the pH value to 8.0, stirred at 45°C for 5 min after condensation, filtered and washed 3 times, then deionized water and 10 g of microporous Y-type molecular sieve were added, mixed thoroughly, and then allowed to stand at room temperature for 12 h, dried in an oven at 110°C for 12 h, and finally calcined at 580°C in an air atmosphere for 5 h to obtain a composite carrier.

[0075] (2) Dissolve 5.7 g of Cu(NO3)2·3H2O and 3.7 g of Zn(NO3)2·6H2O in 20 mL of deionized water. After complete dissolution, add 10 g of the composite support obtained in step (1). After sufficient stirring, let stand for 12 h, dry in an oven at 110°C for 12 h, and then grind. Thereafter, calcine at 580°C in an air atmosphere for 5 h, grind, and press into tablets with a mesh size of 20 to 80 to obtain a composite support dehydrogenation catalyst E.

[0076] Example 6

[0077] A composite support dehydrogenation catalyst for preparing γ-butyrolactone from 1,4-butanediol, the catalyst comprising a Y-type molecular sieve / γ-Al2O3 composite support, an active component loaded on the composite support, and an auxiliary agent. The active component is CuO, the auxiliary agent is ZnO, and the mass ratio of the Y-type molecular sieve and γ-Al2O3 in the composite support is 1:1. The mass content of the copper element is 15% and the mass content of the zinc element is 10% based on the weight ratio of the composite support.

[0078] The method for preparing the composite carrier dehydrogenation catalyst for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol comprises the following steps:

[0079] (1) 15.3 g of aluminum hydroxide, 15.3 g of sodium hydroxide and deionized water were mixed under stirring, reacted for 2 h under boiling conditions to obtain a sodium aluminate solution, and cooled to room temperature; then dilute nitric acid was added to adjust the pH value to 7.5, maintained at 50°C for 0.5 h, and filtered while hot to obtain an aluminum hydroxide gel; dilute ammonia water was added to adjust the pH value to 8.0, stirred at 45°C for 5 min after condensation, filtered and washed 3 times, then deionized water and 10 g of microporous Y-type molecular sieve were added, mixed thoroughly, and then allowed to stand at room temperature for 12 h, dried in an oven at 110°C for 12 h, and finally calcined at 580°C in an air atmosphere for 5 h to obtain a composite carrier.

[0080] (2) Dissolve 5.7 g of Cu(NO3)2·3H2O and 4.6 g of Zn(NO3)2·6H2O in 20 mL of deionized water. After complete dissolution, add 10 g of the composite support obtained in step (1). After sufficient stirring, let stand for 12 h, dry in an oven at 110°C for 12 h, and then grind. Thereafter, calcine at 580°C in an air atmosphere for 5 h, grind, and press into tablets with a mesh size of 20 to 80 to obtain a composite support dehydrogenation catalyst F.

[0081] The performance test of the composite support dehydrogenation catalyst prepared in Examples 4 to 6 was carried out: 1.5g of composite support dehydrogenation catalyst D, E and F were respectively loaded into a fixed bed reactor, and reduction activation was carried out in a pressure of 50kPa and a hydrogen atmosphere, with 120°C as the starting temperature, and gradually increased to 220°C at 10°C / min, and the hydrogen flow rate was controlled at about 80mL / min. After the reduction activation was completed, the raw material was pumped into the vaporizer by a metering pump, and hydrogen and vaporized raw material liquid 1,4-butanediol were passed into the fixed bed reactor, and the molar ratio of hydrogen to 1,4-butanediol was 6:1, and a dehydrogenation reaction was carried out. After 2h of reaction, the reactants were received after cooling, and the crude product was analyzed by gas chromatograph GC9790Plus, and the 1,4-butanediol conversion rate and γ-butyrolactone selectivity of the catalytic reaction were calculated. The specific results are shown in Table 2.

[0082] Table 2 Effect of different zinc contents in catalysts on the performance of dehydrogenation catalysts

[0083]

[0084] As can be seen from Table 2, compared with the catalyst with only active component copper oxide, the conversion rate of 1,4-butanediol and the yield of γ-butyrolactone are both improved. This is because Zn exists in the form of ZnO, which has good electron acceptor properties and can adjust the electron distribution on the Cu surface, thereby improving the Cu o At the same time, the interaction between ZnO and Cu can form a Cu-Zn interface, which can further enhance the dehydrogenation ability of the active center. o The stability of the active sites and the catalytic performance. In addition, the presence of ZnO can effectively reduce the surface acidity of the catalyst, thereby inhibiting the occurrence of dehydration side reactions, reducing the formation of by-products (such as tetrahydrofuran and unsaturated olefin compounds), and improving the selectivity and yield of γ-butyrolactone.

[0085] In addition, keeping the copper content of the active component in the composite support dehydrogenation catalyst unchanged, with the increase of the zinc content of the additive, the conversion rate of 1,4-butanediol gradually increased and then remained basically unchanged, while the selectivity of γ-butyrolactone first increased and then decreased. This is because the addition of zinc improves the activity of the catalyst, resulting in the conversion rate of 1,4-butanediol gradually increasing with the increase of zinc content. However, when the activity of the catalyst has tended to saturation or been inhibited, the conversion rate remains basically unchanged, and excessive zinc may lead to increased side reactions or other adverse effects, resulting in reduced selectivity.

[0086] (III) Investigating the effect of molding steps on the performance of dehydrogenation catalysts

[0087] Example 7

[0088] A composite carrier dehydrogenation catalyst for catalyzing the preparation of gamma-butyrolactone from 1,4-butanediol, wherein the catalyst is obtained by molding the composite carrier dehydrogenation catalyst E prepared in Example 5.

[0089] The molding method of the catalyst for catalyzing the dehydrogenation of 1,4-butanediol to prepare γ-butyrolactone comprises the following steps: weighing 10 g of the composite carrier dehydrogenation catalyst E prepared in Example 5, adding 5 g of pseudo-boehmite, 0.3 g of sesbania powder and 0.5 g of PEG20000 to deionized water and mixing evenly, adding 11 g of 10% dilute nitric acid, kneading, and then drying at room temperature, drying in an oven at 120°C for 4 h, and placing in a muffle furnace at 520°C for 4 h to obtain a composite carrier dehydrogenation catalyst G.

[0090] Referring to the performance test steps of Examples 1 to 3, the performance test of the composite support dehydrogenation catalyst prepared in Example 7 was carried out. The test results are shown in Table 3. 1.5 g of composite support dehydrogenation catalyst E and 1.5 g of composite support dehydrogenation catalyst G were added to the fixed bed reactor respectively. After reacting for 2 hours, the reactants were cooled and received. The continuous reaction was continued for 960 hours. After the reactants were cooled, a group was received every 24 hours. The crude product was analyzed by gas chromatograph GC9790Plus every 1 hour to calculate the 1,4-butanediol conversion rate and γ-butyrolactone selectivity of the catalytic reaction. The specific results are shown in Table 3. Figure 1 and Figure 2 .

[0091] Table 3 Effect of catalyst morphology and reaction time on the performance of dehydrogenation catalyst

[0092]

[0093] It can be seen from Table 3 that after the molding treatment, when the reaction is carried out for 2 hours, the conversion rate of 1,4-butanediol and the selectivity of γ-butyrolactone before and after the molding treatment do not change much. However, when the reaction is carried out for 960 hours, it can be obviously seen that the conversion rate of 1,4-butanediol and the selectivity of γ-butyrolactone using the catalyst after the molding treatment are higher than those of the unmolded catalyst. This is because the mechanical strength, pore structure, surface properties, exposure of the reaction sites and thermal stability of the catalyst are optimized after the molding treatment, and the life of the catalyst is significantly extended.

[0094] pass Figure 1 and Figure 2 It can be seen that with the extension of reaction time, the conversion rate of 1,4-butanediol and the selectivity of γ-butyrolactone remain basically unchanged.

Claims

1. A composite support dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone, characterized in that: Y-type molecular sieve / γ-Al2O3 is used as a composite carrier, and active component copper oxide is loaded; wherein the mass ratio of Y-type molecular sieve and γ-Al2O3 is (1-2):1, and the copper element content is 10%-20% based on the weight ratio of the composite carrier.

2. The composite supported dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 1, characterized in that: It also includes auxiliary zinc oxide, and the zinc content is 6% to 10% based on the weight ratio of the composite carrier.

3. The composite supported dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 2, characterized in that: Also included are pseudo-boehmite, sesbania powder and PEG20000.

4. The method for preparing a composite supported dehydrogenation catalyst for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: dissolving aluminum hydroxide and sodium hydroxide in water, heating for reaction for 2 hours and then cooling to room temperature, adding Y-type molecular sieve after adjusting the pH, and then drying and primary calcination are performed in sequence to obtain a composite carrier Y-type molecular sieve / γ-Al2O3; S2: dissolving a divalent copper salt in water, adding the composite carrier described in S1 to obtain a mixed system, loading the divalent copper salt on the composite carrier by an impregnation method, and then drying and performing a second calcination treatment to obtain a composite carrier dehydrogenation catalyst.

5. The method for preparing a composite supported dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 4, characterized in that: The divalent copper salt is any one of copper sulfate, copper chloride and copper nitrate; the mass ratio of the divalent copper salt to the composite carrier is (0.35-0.8):

1.

6. The method for preparing a composite carrier dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 4, characterized in that: The mixed system also includes a divalent zinc salt; the divalent zinc salt is zinc nitrate or zinc sulfate; the mass ratio of the divalent zinc salt to the composite carrier is (0.25-0.5):

1.

7. The method for preparing a composite carrier dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 4, characterized in that: The mass ratio of the Y-type molecular sieve to γ-Al2O3 in the composite carrier in step S1 is (1-2):

1.

8. The method for preparing a composite carrier dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 4, characterized in that: The temperature of the first calcination is 520-580° C., and the time is 5-6 hours; the temperature of the second calcination is 520-580° C., and the time is 5-6 hours.

9. The method for preparing a composite supported dehydrogenation catalyst for dehydrogenating 1,4-butanediol to prepare γ-butyrolactone according to claim 4, characterized in that: The method further comprises a molding step: mixing the composite carrier dehydrogenation catalyst obtained in step S2 with pseudo-boehmite, sesbania powder and PEG20000, kneading, extruding, air-drying, drying and third calcining.

10. Use of the composite supported dehydrogenation catalyst according to any one of claims 1 to 3 in the dehydrogenation of 1,4-butanediol to prepare γ-butyrolactone.

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