Catalyst for dehydrogenation of 1,4-butanediol to produce gamma-butyrolactone, preparation method and application thereof

Abstract

The present invention belongs to the field of catalytic technology and specifically discloses a catalyst for dehydrogenating 1,4-butanediol to produce γ-butyrolactone, a preparation method thereof, and an application thereof. The catalyst is composed of an active component CuO, an auxiliary agent ZnO, Ca, and a carrier graphene oxide / γ-Al2O3@montmorillonite; by weight, the active component CuO is 20-30%, the auxiliary agent ZnO is 1.5-10%, the auxiliary agent Ca is 0-3%, and the carrier graphene oxide / γ-Al2O3@montmorillonite is 57-78.5%; the graphene oxide / γ-Al2O3@montmorillonite carrier is prepared using graphene oxide and pseudo-boehmite as precursors. The catalyst has a low CuO content, does not contain Cr, is non-toxic and pollution-free, has readily available raw materials, is low in cost, and has high activity.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysis, and particularly relates to a catalyst for dehydrogenating 1,4-butanediol to prepare gamma-butyrolactone, a preparation method and an application thereof. Background Art

[0002] PVP boasts excellent solubility, low toxicity, film-forming properties, chemical stability, physiological inertness, and adhesive properties. It is widely used in the pharmaceutical and healthcare, cosmetics, food, beverage, brewing, papermaking, textile printing and dyeing, new materials, and as a dispersion stabilizer for suspension and emulsion polymerization. In 2021, driven by the new energy sector, the proportion of PVP products used in this sector increased to 10%. The continued expansion of PVP's application areas is also driving the development of the PVP industry. Some experts predict that global demand for PVP will reach 202,000 tons in 2025.

[0003] PVP synthesis processes include the acetylene method and the γ-butyrolactone method. The γ-butyrolactone method has a lower yield and is more suitable for small and medium-sized enterprises. The γ-butyrolactone method involves the reaction of γ-butyrolactone with ethanolamine to produce an aminolysis product, hydroxyethylpyrrolidone (NHP). NHP is then directly or indirectly dehydrated in the presence of a dehydration catalyst to produce the target monomer, NVP. This production process involves the absorption of hazardous substances, making it complex and difficult to control. Furthermore, equipment utilization is generally low, and the NVP yield is lower than that of the acetylene method. The acetylene method is mature and currently the mainstream production process. Using acetylene and formaldehyde as starting materials, the acetylene method synthesizes 1,4-butanediol (BDO). The PVP monomer, NVP, is then obtained through catalytic dehydrogenation, aminolysis, and alkyne addition reactions. The acetylene method is the earliest and most comprehensive method for synthesizing NVP. The main advantages of the acetylene method for producing NVP are its maturity, readily available and affordable raw materials, and its suitability for large-scale industrial production.

[0004] A key step in the acetylene process is the catalytic dehydrogenation of 1,4-butanediol to form γ-butyrolactone. As is well known, the performance of the catalyst is crucial for catalytic reactions. Common catalyst systems for the dehydrogenation of 1,4-butanediol to produce γ-butyrolactone include Cu-Cr catalysts, Cu-Zn catalysts, and those modified with alkali or alkaline earth metals such as K and La. Cu-Cr catalysts are the earliest developed and offer advantages such as long life and good stability. However, Cr is highly toxic and can cause significant pollution. In recent years, Cu-Zn catalysts have garnered increasing attention.

[0005] Chinese patent CN103044367A discloses a catalyst for the dehydrogenation of 1,4-butanediol to γ-butyrolactone. The catalyst first uses a coprecipitation method to prepare a Cu-Zn-Al mixed oxide, which is then loaded with a K or Li additive. The catalyst contains 37-52% copper oxide by weight, achieving a 98% conversion of 1,4-butanediol and 99% selectivity for γ-butyrolactone. CN1562473A uses a precipitation method with an alkaline precipitant to prepare a Cu-Zn-Ce catalyst with a 48-55% copper oxide by weight content. This catalyst achieves a 98% conversion of 1,4-butanediol and nearly 95% selectivity for γ-butyrolactone. The preparation methods for these Cu-Zn catalysts are complex and all contain high copper oxide content. High copper oxide content can easily lead to agglomeration of the active Cu metal, which in turn reduces the yield of the target product.

[0006] Therefore, it is necessary to develop a catalyst for the dehydrogenation of 1,4-butanediol to produce gamma-butyrolactone which has a simple preparation method, high activity, low content of active components, and is non-toxic and pollution-free. Summary of the Invention

[0007] In view of the defects of the prior art, the present invention provides a catalyst for catalyzing the dehydrogenation of 1,4-butanediol to prepare γ-butyrolactone, as well as a preparation method and application thereof. The preparation process is environmentally friendly and non-toxic, and the catalytic activity is good.

[0008] The present invention is achieved through the following technical solutions:

[0009] A catalyst for dehydrogenating 1,4-butanediol to produce γ-butyrolactone, characterized in that the catalyst comprises an active component CuO, an additive ZnO, and Ca, and a carrier graphene oxide / γ-Al2O3@montmorillonite; in terms of weight ratio, the active component CuO accounts for 20-30%, the additive ZnO accounts for 1.5-10%, the additive Ca accounts for 0-3%, and the carrier graphene oxide / γ-Al2O3@montmorillonite accounts for 57-78.5%;

[0010] The graphene oxide / γ-Al2O3@montmorillonite carrier is prepared using graphene oxide and pseudo-boehmite as precursor materials.

[0011] The present application adopts γ-Al2O3 and montmorillonite as the basic matrix materials to make a composite material, which can improve the stability of the carrier and the active components and the adsorption sites of the active components. On the one hand, γ-Al2O3 can play the role of pillaring montmorillonite, thereby increasing the adsorption sites of the carrier and improving the bonding strength between γ-Al2O3 and montmorillonite; on the other hand, montmorillonite can increase the adsorption effect on metal ions. Montmorillonite can also regulate the acidity of γ-Al2O3, which is beneficial to the catalytic effect of the carrier.

[0012] The addition of Ca reacts with γ-Al₂O₃ to form a layered CaAl-LDH hydrotalcite precursor. This CaAl-LDH hydrotalcite precursor simultaneously introduces active metals into the hydrotalcite lamellae, distributing them uniformly and densely. The ratio of metal cations can be adjusted to a certain extent, resulting in the formation of a composite metal oxide upon subsequent calcination. This uniform dispersion of active metals enhances catalyst activity. The formation of the composite metal oxide also increases the basicity of the hydrotalcite material, ultimately improving the basicity of the final catalyst, making it particularly suitable for alcohol dehydrogenation reactions.

[0013] The matrix material is then graphene-oxidized to form a graphene oxide carrier. Graphene oxide contains hydroxyl, carboxyl, epoxy, and aldehyde oxygen groups that provide coordination capacity. This allows for better adsorption of active metals such as Cu and Zn, forming chemical bonds and thereby enhancing the bond strength with the metal ions. The presence of calcium also acts as a co-catalyst.

[0014] Conversely, pseudo-boehmite can also use montmorillonite and graphene oxide as templates to improve the uniform dispersion of pseudo-boehmite on montmorillonite and graphene oxide, avoid the agglomeration of pseudo-boehmite, and at the same time improve the adsorption of active components, thereby improving the catalytic activity of the catalyst.

[0015] A method for preparing a catalyst for dehydrogenating 1,4-butanediol to produce gamma-butyrolactone comprises the following steps:

[0016] S1, dissolving pseudo-boehmite and montmorillonite in a dispersant, and then adding the mixture into a mechanochemical reactor to react to obtain a first suspension;

[0017] S2, adding CaO to deionized water and ultrasonically forming a second suspension of calcium hydroxide;

[0018] S3, ultrasonically dispersing graphene oxide in distilled water, adding the first suspension and the second suspension dropwise and continuing ultrasonication until the suspension has a uniform color to obtain a third suspension; then adding alkaline solution for co-precipitation to obtain a solution containing suspended solids, which is recorded as the fourth solution;

[0019] S4, dissolving soluble salts of copper and zinc in water, and adding an alkaline buffer solution to control the alkalinity of the solution, to obtain a solution containing suspended solids, which is recorded as the fifth solution;

[0020] S5, adding the fourth solution to the fifth solution, stirring and mixing, aging, then rinsing with deionized water until neutral, and drying to obtain a precursor having a hydrotalcite structure;

[0021] S6, calcining the precursor having a hydrotalcite structure in an air atmosphere at 300-500° C. for 2-6 hours to obtain the catalyst;

[0022] Preferably, in the above steps, the mass ratio of pseudo-boehmite, montmorillonite, dispersant and graphene oxide is 1-1.5:1-1.2:8-10:0.002-0.005.

[0023] Furthermore, the dispersant used in step S1 is an ethylene glycol aqueous solution;

[0024] Preferably, the volume ratio of ethylene glycol to water in the ethylene glycol aqueous solution is 3:1.

[0025] Furthermore, the alkali solution used in step S3 is one of ammonia water, sodium bicarbonate, sodium hydroxide, and ammonium carbonate;

[0026] Preferably, the pH value of the fourth solution is controlled to be between 9 and 11.

[0027] Furthermore, in step S4, the soluble salt of copper and zinc is at least one of nitrate, acetate, and basic carbonate, preferably nitrate.

[0028] Furthermore, the alkaline buffer solution in step S4 is a mixed solution of sodium hydroxide and sodium carbonate;

[0029] Preferably, the pH value of the fifth solution is controlled to be between 8 and 10.

[0030] Furthermore, the powder obtained by calcining in the step S6 is pressed into a cylinder with a diameter of 3 to 5 mm using a tablet press with a punch pressure of 70 to 120 kN.

[0031] Furthermore, the catalyst is used in the selective dehydrogenation reaction of alcohol substances.

[0032] Furthermore, the alcohol substance is one of ethanol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-propylene glycol, cyclohexanol, and isopropanol; in the selective dehydrogenation reaction of the alcohol substance, the reaction temperature is 210°C to 280°C, the reaction pressure is 0.1 to 2.0 Bar, and the reaction pressure is gauge pressure.

[0033] The beneficial effects of the present invention are:

[0034] 1. The catalyst of the present invention requires a small amount of CuO as the active component, and the active components are not easy to agglomerate during use; the catalyst does not contain Cr, is non-toxic and non-polluting; the raw materials are easily available and the cost is low; and the resulting catalyst has high activity.

[0035] 2. The catalyst of the present invention is mainly prepared by ultrasonic cavitation and co-precipitation. The preparation method is simple, the raw materials used are simple and easy to obtain, the cost is saved, and it is suitable for popularization and use.

[0036] 3. The catalyst of the present invention can be used in the selective dehydrogenation reaction of ethanol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-propylene glycol, cyclohexanol and isopropanol. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0038] (1) The present invention provides a catalyst for dehydrogenating 1,4-butanediol to produce γ-butyrolactone, the catalyst comprising an active component CuO, an auxiliary agent ZnO, Ca, and a carrier graphene oxide / γ-Al2O3@montmorillonite; in terms of weight ratio, the active component CuO accounts for 20-30%, the auxiliary agent ZnO accounts for 1.5-10%, the auxiliary agent Ca accounts for 0-3%, and the carrier graphene oxide / γ-Al2O3@montmorillonite accounts for 57-78.5%;

[0039] The graphene oxide / γ-Al2O3@montmorillonite carrier is prepared using graphene oxide and pseudo-boehmite as precursor materials.

[0040] (2) The present invention provides a method for preparing a catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone, comprising the following steps:

[0041] S1, dissolving pseudo-boehmite and montmorillonite in a dispersant, and then adding the mixture into a mechanochemical reactor to react to obtain a first suspension;

[0042] S2, adding CaO to deionized water and ultrasonically forming a second suspension of calcium hydroxide;

[0043] S3, ultrasonically dispersing graphene oxide in distilled water, adding the first suspension and the second suspension dropwise and continuing ultrasonication until the suspension has a uniform color to obtain a third suspension; then adding alkaline solution for co-precipitation to obtain a solution containing suspended solids, which is recorded as the fourth solution;

[0044] S4, dissolving soluble salts of copper and zinc in water, and adding an alkaline buffer solution to control the alkalinity of the solution, to obtain a solution containing suspended solids, which is recorded as the fifth solution;

[0045] S5, adding the fourth solution to the fifth solution, stirring and mixing, aging, then rinsing with deionized water until neutral, and drying to obtain a precursor having a hydrotalcite structure;

[0046] S6, calcining the precursor having a hydrotalcite structure in an air atmosphere at 300-500° C. for 2-6 hours to obtain the catalyst;

[0047] In the above steps, the mass ratio of pseudo-boehmite, montmorillonite, dispersant and graphene oxide is 1-1.5:1-1.2:8-10:0.002-0.005.

[0048] In the present invention, the dispersant is an ethylene glycol aqueous solution, and the volume ratio of ethylene glycol to water in the ethylene glycol aqueous solution is 3:1.

[0049] In the present invention, in S1, the operating parameters of the mechanochemical reactor are a time of 1.5 hours to 3 hours and a temperature of 80°C to 100°C. Preferably, step S1 is to first dissolve half of the pseudo-boehmite and montmorillonite in the whole dispersant, stir and react in the mechanical reactor, then add the remaining half of the pseudo-boehmite and montmorillonite, and stir and react to obtain the first suspension.

[0050] In the present invention, in S2, the ultrasonic temperature is 60-80°C, and the ultrasonic time is 0.2-0.5h.

[0051] In the present invention, in S3, the ultrasonic temperature is 60-80°C, and the ultrasonic time is 1-2h.

[0052] In the present invention, the alkali solution used in step S3 is one of ammonia water, sodium bicarbonate, sodium hydroxide, and ammonium carbonate; preferably, the pH value of the fourth solution is controlled to be 9-11.

[0053] In the present invention, the soluble salt of copper or zinc in step S4 is at least one of nitrate, acetate, and basic carbonate, preferably nitrate. The alkaline buffer in step S4 is a mixed solution of sodium hydroxide and sodium carbonate. Preferably, the pH value of the fifth solution is controlled to be between 8 and 10.

[0054] In the present invention, the powder obtained by calcining in step S6 is pressed into a cylinder with a diameter of 3 to 5 mm using a tablet press with a punch pressure of 70 to 120 kN.

[0055] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the catalyst for catalytic dehydrogenation of alcohols provided by the present invention, its preparation method and application are described in detail below with specific examples.

[0056] Example 1

[0057] A catalyst for catalyzing the dehydrogenation of alcohols, wherein the preparation method thereof may specifically include the following steps:

[0058] S1. Dissolving half of the pseudo-boehmite and montmorillonite in the whole dispersant, adding the mixture to a mechanochemical reactor, stirring for reaction, and then adding the other half of the pseudo-boehmite and montmorillonite to react to obtain a first suspension; wherein the mass ratio of the pseudo-boehmite, montmorillonite, dispersant, and graphene oxide is 1:1:8:0.002; the dispersant is an ethylene glycol aqueous solution, and the volume ratio of ethylene glycol to water in the ethylene glycol aqueous solution is 3:1; the operating parameters of the mechanochemical reactor are time 1.5 h and temperature 80°C;

[0059] S2, adding 0 g of CaO to deionized water and ultrasonicating at 60° C. for 0.2 h to form a second suspension of calcium hydroxide;

[0060] S3. Disperse 1.57 g of graphene oxide in distilled water by ultrasonication at 60° C. for 1 h, add the first suspension and the second suspension dropwise, and continue ultrasonication until the suspension has a uniform color to obtain a third suspension; then add ammonia water for coprecipitation to obtain a solution containing suspended solids, which is recorded as a fourth solution; the pH value of the fourth solution is controlled at 9.4-9.5;

[0061] S4. Dissolve 47 g of copper nitrate and 3.5 g of zinc nitrate in water, and add a mixed solution of sodium hydroxide and sodium carbonate to control the solution to be alkaline, to prepare a solution containing suspended solids, recorded as the fifth solution; the pH value of the fifth solution is controlled at 8.2-8.3;

[0062] S5, adding the fourth solution to the fifth solution, stirring and mixing, aging for 3 to 4 hours, then rinsing with deionized water until neutral, and drying the filter cake at 100 to 130° C. to obtain a precursor having a hydrotalcite structure;

[0063] S6, after grinding the precursor with the hydrotalcite structure, calcining it at 300 ℃ in an air atmosphere for 2 hours, adding a small amount of graphite powder after natural cooling, using a single punch tablet press (produced by Longli, a Chinese medicine company) under a punch pressure of 110KN, tableting is formed into a cylindrical catalyst of Φ5×3~4mm, thereby preparing a catalyst for catalytic dehydrogenation of alcohols. The content of each component in the catalyst is 78.5wt% of the carrier, 20wt% of CuO, 1.5wt% of ZnO, and 0.

[0064] Example 2

[0065] The difference between this embodiment and embodiment 1 is that the mass ratio of pseudo-boehmite, montmorillonite, dispersant and graphene oxide is 1.5:1.2:10:0.005.

[0066] Example 3

[0067] The difference between this embodiment and embodiment 1 is that the mass ratio of pseudo-boehmite, montmorillonite, dispersant, and graphene oxide is 1.2:1.2:9:0.003.

[0068] Example 4

[0069] The difference between this embodiment and embodiment 1 is that the operating parameters of the mechanical chemical reactor in step S1 are: time 3 hours, temperature 100°C; in step S2, the ultrasonic temperature is 80°C, and the ultrasonic time is 0.5 hours; in step S3, the ultrasonic temperature is 80°C, and the ultrasonic time is 2 hours; in step S6, the calcination temperature is 500°C, and the calcination time is 6 hours.

[0070] Example 5

[0071] The difference between this embodiment and embodiment 1 is that the operating parameters of the mechanical chemical reactor in step S1 are time 2 hours and temperature 90°C; the ultrasonic temperature in step S2 is 70°C and the ultrasonic time is 0.35 hours; the ultrasonic temperature in step S3 is 70°C and the ultrasonic time is 1.5 hours; and the calcination temperature in step S6 is 400°C and the calcination time is 4.5 hours.

[0072] Example 6

[0073] The difference between this embodiment and embodiment 1 is that, in the preparation of the catalyst, the alkali solution used in step S3 is sodium bicarbonate, and the pH value of the fourth solution is controlled at 9.6 to 9.7; the soluble salts of copper and zinc described in step S4 are copper acetate and zinc acetate, and the pH value of the fifth solution is controlled at 8.6 to 8.7.

[0074] Example 7

[0075] The difference between this embodiment and embodiment 1 is that, in the preparation of the catalyst, the alkali solution used in step S3 is sodium hydroxide, and the pH value of the fourth solution is controlled at 10.4-10.5; the soluble salts of copper and zinc described in step S4 are basic copper carbonate and basic zinc carbonate, and the pH value of the fifth solution is controlled at 9.2-9.3.

[0076] Example 8

[0077] The difference between this embodiment and embodiment 1 is that, in the preparation of the catalyst, the alkali solution used in step S3 is ammonium carbonate, and the pH value of the fourth solution is controlled at 10.6 to 10.7; the soluble salts of copper and zinc described in step S4 are copper nitrate and zinc nitrate, and the pH value of the fifth solution is controlled at 9.5 to 9.6.

[0078] Example 9

[0079] This example differs from Example 1 in that, in the catalyst preparation, 7 g of CaO is added in step S2, 70.5 g of copper nitrate is added in step S4, and 23.34 g of zinc nitrate is added. The content of each component in the resulting catalyst is 57 wt % of the carrier, 30 wt % of CuO, 10 wt % of ZnO, and 3 wt % of Ca.

[0080] Example 10

[0081] This example differs from Example 1 in that, in the catalyst preparation, 3.5 g of CaO is added in step S2, 35 g of copper nitrate is added in step S4, and 11.67 g of zinc nitrate is added. The content of each component in the resulting catalyst is 67 wt % of the carrier, 25 wt % of CuO, 6 wt % of ZnO, and 2 wt % of Ca.

[0082] Example 11

[0083] The difference between this embodiment and embodiment 1 is that in the preparation of the catalyst, 0.5 g of CaO is added in step S2. The contents of the components in the resulting catalyst are 77 wt% of the carrier, 21 wt% of CuO, 1.65 wt% of ZnO, and 0.35 wt% of Ca.

[0084] Example 12

[0085] The difference between this embodiment and embodiment 1 is that in the preparation of the catalyst, 3.5 g of CaO is added in step S2. The contents of the components in the resulting catalyst are 74 wt% of the carrier, 22 wt% of CuO, 2.15 wt% of ZnO, and 1.85 wt% of Ca.

[0086] Comparative Example 1

[0087] The catalyst was prepared by the preparation method of the present application, wherein the carrier was γ-Al2O3, CuO was the active component, and ZnO was the auxiliary agent, wherein γ-Al2O3 accounted for 78.5wt%, CuO was 20wt%, and ZnO was 1.5wt%.

[0088] Comparative Example 2

[0089] The difference between this embodiment and embodiment 1 is that the mass ratio of pseudo-boehmite, montmorillonite, dispersant, and graphene oxide is 0.8:1.2:10:0.005.

[0090] Comparative Example 3

[0091] The difference between this embodiment and embodiment 1 is that the mass ratio of pseudo-boehmite, montmorillonite, dispersant, and graphene oxide is 1.7:1:8:0.002.

[0092] Comparative Example 4

[0093] The difference between this embodiment and embodiment 1 is that no pseudo-boehmite is added during the preparation of the catalyst.

[0094] Comparative Example 5

[0095] The difference between this embodiment and embodiment 1 is that no montmorillonite is added during the preparation of the catalyst.

[0096] Comparative Example 6

[0097] The difference between this embodiment and embodiment 1 is that graphene oxide is not added during the preparation of the catalyst.

[0098] Comparative Example 7

[0099] The difference between this embodiment and embodiment 1 is that in the catalyst preparation process, in step S1, all the pseudo-boehmite and montmorillonite are first dissolved in the whole dispersant, and then stirred in a mechanical reactor for uniform reaction to obtain a first suspension.

[0100] The parameters for the catalyst preparation in Examples 1-12 are shown in Table 1 below.

[0101] Table 1 Catalyst preparation parameters in Examples 1-12

[0102]

[0103] The parameters of the components of the products prepared in Examples 1, 9, 10, 11 and 12 are shown in Table 2.

[0104] Table 2. Parameters of the components of the products obtained in Examples 1, 9, 10, 11, and 12

[0105] sample carrier CuO ZnO Ca Example 1 78.5wt% 20wt% 1.5wt% 0 Example 9 57wt% 30wt% 10wt% 3wt% Example 10 67wt% 25wt% 6wt% 2wt% Example 11 77wt% 21wt% 1.65wt% 0.35wt% Example 12 74wt% 22wt% 2.15wt% 1.85wt%

[0106] Application Example 1

[0107] The catalyst for catalytic dehydrogenation of alcohols prepared in Example 1 of the present invention is used for ethanol dehydrogenation reaction.

[0108] The catalyst for catalytic dehydrogenation of alcohols prepared in Example 1 of the present invention was first reduced with a mixture of hydrogen and nitrogen (hydrogen content 5 vol%) before being fed into the ethanol dehydrogenation reaction. The reduction was carried out at normal pressure and a maximum temperature of 270° C., thereby obtaining a hydrogen-reduced catalyst.

[0109] The ethanol dehydrogenation reaction is carried out in a fixed bed reactor, in which 2 g of the hydrogen-reduced catalyst is loaded, under the conditions of a reaction temperature of 260° C. and normal pressure, with nitrogen as the accompanying gas, a nitrogen to ethanol molar ratio of 8:1, and a liquid hourly space velocity (LHSV) of 0.8 g·gcat. -1 ·h -1After the reaction stabilized, the reaction raw materials and products were analyzed by online chromatography, and the reaction results were tested 12, 48, 96 and 120 hours after the feeding, respectively, so as to obtain the experimental results shown in Table 3 below; In Table 3, the conversion rate of Application Example 1 is the conversion rate of ethanol into other substances, and the selectivity of Application Example 1 is the selectivity of the target product acetaldehyde.

[0110] Application Examples 2-20

[0111] The catalysts for catalytic dehydrogenation of alcohols prepared in Examples 1 to 12 of the present invention and Comparative Examples 1 to 7 were used in the dehydrogenation reaction of 1,4-butanediol.

[0112] Specifically, before being fed into the dehydrogenation reaction of 1,4-butanediol, a mixture of hydrogen and nitrogen (hydrogen content 5 vol%) is firstly reduced at normal pressure with a maximum temperature of 260° C., thereby obtaining a hydrogen-reduced catalyst.

[0113] The 1,4-butanediol dehydrogenation reaction is carried out in a fixed bed reactor. 2 g of the hydrogen-reduced catalyst is loaded into the reactor. Under the conditions of a reaction temperature of 240° C. and normal pressure, hydrogen is used as an accompanying gas. The molar ratio of hydrogen to 1,4-butanediol is 8:1 to adjust the 1,4-butanediol gas phase concentration. The liquid hourly space velocity (LHSV) of the butanediol is 2.7 g·gcat. -1 ·h -1 After the reaction stabilized, the reaction raw materials and products were condensed and analyzed by offline chromatography. The reaction results were tested 12, 48, 96, and 120 hours after the feed, respectively, to obtain the experimental results shown in Table 3 below. In Table 3, the conversion rates of Application Examples 2 to 20 are the conversion rates of 1,4-butanediol to other substances, and the selectivities of Application Examples 2 to 20 are the selectivities of the target product γ-butyrolactone.

[0114] Table 3

[0115]

[0116] The experimental results in Table 3 show that the experimental data of the embodiment group are higher than those of the comparative example group, and the conversion rate and selectivity do not change significantly within 12 to 120 hours. This shows that the catalyst of the present invention has good stability. Under the condition of 6 times the conventional production space velocity of 1,4-butanediol to γ-butyrolactone, it enters a steady state within 48 hours, and the reaction results do not change within 120 hours.

[0117] The embodiment group is compared with comparative example 1 and can be known that, with conventional γ-Al2O3, adopt the catalyst support of the present application, the catalyst technology effect obtained is better. The embodiment group is compared with comparative examples 2 to 7, and adopts each component of the present application and the catalyst support within the limited range its technology effect is better. Compared with the Cu-Zn-Al catalyst reported by Sinopec (patent No. is embodiment 3-6 and comparative example 1 in CN103044367B) in the prior art, the 1,4-butanediol conversion rate and gamma-butyrolactone selectivity of the catalyst (low Cu component) of the present application have all reached higher levels. As can be seen from the comparative data of embodiment 1 and embodiment 11,12, the addition of CaO has a promoting effect on the conversion rate and selectivity of the catalyst.

Claims

1. A catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone, characterized in that: The catalyst is composed of an active component CuO, an auxiliary agent ZnO, and a carrier graphene oxide / γ-Al2O3@montmorillonite. In terms of weight ratio, the active component CuO accounts for 20-30%, the auxiliary agent ZnO accounts for 1.5-10%, and the carrier graphene oxide / γ-Al2O3@montmorillonite accounts for 57-78.5%. The graphene oxide / γ-Al2O3@montmorillonite carrier is prepared using graphene oxide and pseudo-boehmite as precursors; The method for preparing the catalyst for dehydrogenating 1,4-butanediol to produce γ-butyrolactone comprises the following steps: S1. Dissolve half of the pseudo-boehmite and montmorillonite in the whole dispersant, then place in a mechanochemical reactor, stir and react, then add the other half of the pseudo-boehmite and montmorillonite to react to obtain a first suspension; S2, adding CaO to deionized water and ultrasonically forming a second suspension of calcium hydroxide; S3, ultrasonically dispersing graphene oxide in distilled water, adding the first suspension and the second suspension dropwise and continuing ultrasonication until the suspension has a uniform color to obtain a third suspension; then adding alkaline solution for co-precipitation to obtain a solution containing suspended solids, which is recorded as the fourth solution; S4, dissolving soluble salts of copper and zinc in water, and adding an alkaline buffer solution to control the solution to be alkaline, to prepare a solution containing suspended solids, recorded as the fifth solution; S5, adding the fourth solution to the fifth solution, stirring and mixing, aging, then rinsing with deionized water until neutral, and drying to obtain a precursor having a hydrotalcite structure; S6, calcining the precursor having a hydrotalcite structure in an air atmosphere at 300-500° C. for 2-6 hours to obtain the catalyst; In the above steps, the mass ratio of pseudo-boehmite, montmorillonite, dispersant and graphene oxide is 1-1.5:1-1.2:8-10:0.002-0.

005.

2. The catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone according to claim 1, characterized in that The dispersant used in step S1 is an ethylene glycol aqueous solution, and the catalyst further includes an additive Ca, and the content of Ca is greater than 0 and less than or equal to 3% by weight.

3. The catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone according to claim 2, characterized in that: The volume ratio of ethylene glycol to water in the ethylene glycol aqueous solution is 3:

1.

4. The catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone according to claim 1, characterized in that The alkali solution used in step S3 is one of ammonia water, sodium bicarbonate, sodium hydroxide, and ammonium carbonate; The pH value of the fourth solution is controlled to be between 9 and 11.

5. The catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone according to claim 1, characterized in that In step S4, the soluble salt of copper and zinc is at least one of nitrate, acetate and basic carbonate.

6. The catalyst for dehydrogenating 1,4-butanediol to γ-butyrolactone according to claim 1, characterized in that The alkaline buffer solution in step S4 is a mixed solution of sodium hydroxide and sodium carbonate; The pH value of the fifth solution is controlled to be between 8 and 10.

7. The catalyst for dehydrogenation of 1,4-butanediol to γ-butyrolactone according to claim 1, characterized in that The powder obtained by calcining in step S6 is compressed into a cylinder with a diameter of 3 to 5 mm using a tablet press with a punch pressure of 70 to 120 kN.

8. Use of the catalyst according to any one of claims 1 to 7, characterized in that: The catalyst is used in the reaction of dehydrogenating 1,4-butanediol to prepare γ-butyrolactone.

9. Use of the catalyst according to claim 8, characterized in that The catalyst is used in the reaction of dehydrogenating 1,4-butanediol to prepare gamma-butyrolactone. The reaction temperature is 210° C. to 280° C., and the reaction pressure is 0.1 to 2.0 Bar, where the reaction pressure is gauge pressure.

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