A dehydrogenation catalyst and a preparation method, and a method for preparing gamma-butyrolactone by dehydrogenating 1,4-butanediol

Abstract

A preparation method of a dehydrogenation catalyst and a method for preparing gamma-butyrolactone by dehydrogenating 1,4-butanediol, the catalyst is prepared by co-precipitation method to prepare a slurry of copper and zinc composite oxide, co-precipitation method is used to prepare a slurry of copper, chromium and zirconium composite oxide, the two slurries are mixed, reacted, dried and calcined to obtain a mixture, and then the mixture is impregnated in a salt solution of M element; M element is selected from at least one of Li, Na, K, Ca, Mg and Ba. According to the present application, the active metal copper is distributed on different carriers by step-by-step precipitation, the dispersion degree is high, the H2 adsorption and desorption, dehydrogenation reaction, anchoring of active copper particles and other multifunctional coupling are realized, high catalytic activity is exhibited, the catalyst can be activated at a lower temperature, energy consumption is saved, and because the side reaction of BDO dehydration to form tetrahydrofuran is an endothermic reaction, therefore, reducing the reaction temperature is beneficial to inhibiting the formation of tetrahydrofuran; the addition of M element can weaken the dehydration active center and further inhibit the formation of tetrahydrofuran, so as to improve the selectivity of the catalyst.

Description

Technical Field

[0001] This invention relates to a dehydrogenation catalyst and its preparation method, as well as a method for using it to catalyze the gas-phase dehydrogenation and cyclization of 1,4-butanediol to prepare γ-butyrolactone, belonging to the field of catalysis technology. Background Technology

[0002] γ-Butyrolactone (GBL), also known as 1,4-butyrolactone or 4-hydroxybutyric acid lactone, is an important fine chemical intermediate. It can dissolve a variety of organic and inorganic compounds and is commonly used as an organic solvent, extractant, and absorbent. In lithium batteries and electrical appliances, it serves as a special solvent with high conductivity in electrolytes. It can also be used to prepare high-value-added products such as ciprofloxacin, Cerebrolysin, vitamin K4, polyvinylpyrrolidone, and N-methylpyrrolidone (NMP). GBL and its derivatives are widely used in the petrochemical, textile, fragrance, pesticide, and pharmaceutical industries.

[0003] Currently, the mainstream process for GBL production is the 1,4-butanediol (BDO) dehydrogenation cyclization method. This reaction is endothermic and therefore requires high temperatures. However, high temperatures also promote dehydration side reactions, generating tetrahydrofuran and n-butanol. Therefore, it is necessary to develop highly selective dehydrogenation catalysts to suppress the active centers of the dehydration reaction. Existing BDO dehydrogenation processes for GBL production mostly use Cu-based catalysts, with operating temperatures generally above 220℃. Furthermore, the presence of Al2O3 binders introduces acid centers into the catalyst, promoting dehydration side reactions and leaving room for improvement in the selectivity of the target product, GBL. CN201410006754.8 discloses a catalyst for the atmospheric pressure gas-phase dehydrogenation of BDO to GBL and its preparation method. This catalyst is composed of CuO, ZnO, Al2O3, and SiO2, and is prepared at 240℃ for 2.0 h. -1 Under the specified reaction conditions, the BDO conversion rate was 99.1%, the GBL selectivity was 97.6%, and the reaction temperature was relatively high. CN202011253758.8 discloses a dehydrogenation catalyst and its preparation method. The dehydrogenation catalyst is composed of CuO, ZnO, and ZrO2, and the reaction is carried out at 220℃ for 2.0 h. -1 Under the given reaction conditions, the BDO conversion rate was 99.6 mol%, and the GBL yield was 99.1 mol%, indicating room for further reduction in reaction temperature. CN202311600519.9 discloses a catalyst for the dehydrogenation of BDO to GBL and its preparation method. This catalyst incorporates the noble metal Pd and reacts at 220℃, 0.5 atm, and 0.3 h. -1Under the given reaction conditions, the BDO conversion was 99.1% and the GBL selectivity was 99.6%. This invention utilizes a noble metal catalyst, but the reaction space velocity is relatively low, and the reaction efficiency still needs improvement. Therefore, existing catalysts for the dehydrogenation of BDO to GBL still have room for improvement in terms of catalyst activity and selectivity, as well as in reducing the reaction temperature. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a dehydrogenation catalyst and its preparation method. The catalyst prepared by this invention can achieve highly selective dehydrogenation of BDO at relatively low temperatures and high space velocities, exhibiting high reaction efficiency while reducing reaction energy consumption and facilitating industrialization.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a dehydrogenation catalyst includes the following steps:

[0007] (1) Add a precipitant to a mixed solution of soluble copper salt and soluble zinc salt, stir and react, and age to obtain slurry I; add a precipitant to a mixed solution of soluble copper salt, soluble chromate and soluble zirconium salt, stir and react, and age to obtain slurry II;

[0008] (2) Mix slurry I and slurry II, stir and react, age, and then filter, wash, dry and calcinate to obtain a solid mixture;

[0009] (3) Prepare a solution with a salt containing element M, impregnate the solid mixture obtained in step (2), dry, calcine, and press into tablets to obtain the dehydrogenation catalyst; the element M is selected from at least one of Li, Na, K, Ca, Mg and Ba;

[0010] The amount of each raw material fed is based on the following composition of the catalyst: 20-40% copper oxide, 15-30% zinc oxide, 20-40% chromium oxide, 15-30% zirconium oxide, and 0.2-3.0% oxide of M; wherein, based on the total amount of copper, the ratio of copper in slurry I and slurry II is 1:1-1:5.

[0011] Furthermore, in step (1), the reaction temperature after adding the precipitant is 25-80℃, and the stirring reaction time is 1-10 hours.

[0012] Furthermore, the soluble copper salt, soluble zinc salt, and soluble zirconium salt mentioned in step (1) are selected from at least one of soluble nitrates, chlorides, acetates, and sulfates, preferably nitrates; the soluble chromate is at least one of sodium chromate and sodium dichromate.

[0013] Furthermore, the concentrations of the soluble copper salt, soluble zinc salt, soluble zirconium salt, and soluble chromate mentioned in step (1) are 0.2-2.0 mol / L.

[0014] Furthermore, the precipitant in step (1) is selected from at least one of ammonia, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate and potassium hydroxide aqueous solution.

[0015] Furthermore, the concentration of the precipitant in step (1) is 0.5-3.0 mol / L, and its dosage ensures that the pH of the final precipitated solution is ≥8.

[0016] Furthermore, the aging conditions described in step (1) are a temperature of 25-80℃ and an aging time of 2-12h.

[0017] Furthermore, in step (2), the ratio of copper in slurry I and slurry II is 1:1 to 1:3.

[0018] Furthermore, in step (2), the aging conditions are: temperature 25-80℃, aging time 2-12h.

[0019] Furthermore, the washing described in step (2) involves washing multiple times with deionized water until the conductivity of the washing water is no greater than 1000 μs / cm.

[0020] Furthermore, the drying temperature in step (2) is 110-150℃, and the time is 4-12h. The calcination temperature is 300-800℃, and the time is 2-8h.

[0021] Furthermore, the drying temperature in step (3) is 110-150℃, and the time is 4-12h. The calcination temperature is 300-600℃, and the time is 2-8h.

[0022] The technical objective of the second aspect of this invention is to provide a dehydrogenation catalyst prepared by the above-described preparation method.

[0023] The technical objective of the third aspect of this invention is to provide a method for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol, wherein 1,4-butanediol is reacted with the catalyst to obtain γ-butyrolactone.

[0024] Furthermore, before the reaction, the dehydrogenation catalyst is first reduced in a hydrogen-containing atmosphere at 150-320°C.

[0025] The dehydrogenation reaction was carried out in a fixed-bed reactor under the following conditions: reaction temperature 180-260℃, preferably 180-220℃, reaction pressure 0.01-0.3 MPaG, and liquid hourly space velocity (LHSV) 0.2-5 h⁻¹. -1The molar ratio of H2 to BDO is 2-20, preferably 3-10.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The catalyst used in this invention, through stepwise precipitation, distributes active metallic copper on different supports at different concentrations, exhibiting high dispersion. This allows for multifunctional coupling of H2 adsorption and desorption, dehydrogenation reactions, and anchoring of active copper particles, resulting in high catalytic activity. The catalyst can be activated at lower temperatures, saving energy. Furthermore, since the side reaction of BDO dehydration to tetrahydrofuran is thermodynamically endothermic, lowering the reaction temperature is thermodynamically beneficial for suppressing tetrahydrofuran formation and also kinetically beneficial for reducing the reaction coefficient of the dehydration reaction. In addition, the addition of element M weakens the active dehydration centers, further inhibiting tetrahydrofuran formation and achieving the goal of improving catalyst selectivity.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0029] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0030] In the examples, the purity of materials and the composition of products were analyzed by gas chromatography, and the GBL analysis method was based on HG / T4989-2016.

[0031] Example 1

[0032] Catalyst preparation:

[0033] (1) Prepare a 2 mol / L KOH solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 27.8 g Cu(NO3)2·3H2O and 81.2 g Zn(NO3)2·6H2O in 200 mL of deionized water, stir continuously in a constant temperature water bath at 40℃, slowly add KOH solution, control the pH to 8-9, precipitate for 40 min, and age for 2 h after precipitation to obtain slurry I; dissolve 55.5 g Cu(NO3)2·3H2O, 86.8 g Zr(NO3)4·5H2O and 37.3 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 40℃, slowly add KOH solution, control the pH to 10-11, precipitate for 40 min, and age for 2 h after precipitation to obtain slurry II;

[0034] (2) Mix the slurry I and slurry II after aging and continue aging in a water bath at 40°C for 2 hours. After aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000 μs / cm, dry the filter cake at 110°C for 12 hours, and calcine it at 500°C for 4 hours to obtain a solid mixture.

[0035] (3) Dissolve 5.9 g of Ca(NO3)2·4H2O in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 110 °C, and calcine at 380 °C for 4 h to obtain catalyst G1. XRF analysis showed that, by weight percentage, the content of CuO was 27.4%, ZrO2 was 24.9%, ZnO was 22.1%, Cr2O3 was 24.2%, and CaO was 1.4%; N2 adsorption-desorption analysis showed a specific surface area of ​​92.4 m². 2 / g.

[0036] Catalytic dehydrogenation of 1,4-butanediol:

[0037] Catalyst G1 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a stainless steel tubular fixed-bed reactor with an inner diameter of 20 mm and a length of 500 mm for dehydrogenation reaction. Before the reaction, the catalyst was reduced at 280℃ for 4 h in a hydrogen atmosphere. After reduction, the temperature was lowered to 200℃, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction pressure was 0.15 MPa, and the hydrogen-to-ethanol molar ratio was 7. After 3 hours of stabilization, the BDO conversion was 99.8%, the GBL selectivity was 99.6%, and the yield was 99.4%.

[0038] Example 2

[0039] Catalyst preparation:

[0040] (1) Prepare a 2 mol / L KOH solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 35.6 g Cu(NO3)2·3H2O and 91.1 g Zn(NO3)2·6H2O in 200 mL of deionized water, stir continuously in a constant temperature water bath at 60℃, slowly add KOH solution, control the pH to 8-9, precipitate for 40 min, and age for 6 h after precipitation to obtain slurry I; dissolve 71.1 g Cu(NO3)2·3H2O, 61.7 g Zr(NO3)4·5H2O and 30.5 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 60℃, slowly add KOH solution, control the pH to 10-11, precipitate for 40 min, and age for 2 h after precipitation to obtain slurry II;

[0041] (2) Mix the slurry I and slurry II after aging and continue aging in a water bath at 60°C for 6 hours. After aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000 μs / cm, dry the filter cake at 110°C for 12 hours, and calcine it at 700°C for 4 hours to obtain a solid mixture.

[0042] (3) Dissolve 5.6 g of KNO3 in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 120 °C, and calcine at 400 °C for 4 h to obtain catalyst G2. XRF analysis showed that, by weight percentage, the content of CuO was 35.1%, ZrO2 was 17.7%, ZnO was 24.8%, and Cr2O3 was 19.8%.

[0043] The K₂O content is 2.6%; the specific surface area, as determined by N₂ adsorption-desorption, is 83.7 m². 2 / g.

[0044] Catalytic dehydrogenation of 1,4-butanediol:

[0045] Catalyst G2 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 270 °C for 4 h in a hydrogen atmosphere. After reduction, the temperature was lowered to 210 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 2 h⁻¹. -1 The reaction pressure was 0.2 MPa, and the hydrogen-to-ethanol molar ratio was 7. After 3 hours of stabilization, the BDO conversion was 99.6%, the GBL selectivity was 99.7%, and the yield was 99.3%.

[0046] Example 3

[0047] Catalyst preparation:

[0048] (1) Prepare a 2 mol / L KOH solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 36.3 g Cu(NO3)2·3H2O and 80.4 g Zn(NO3)2·6H2O in 200 mL of deionized water, stir continuously in a constant temperature water bath at 80℃, slowly add KOH solution, control the pH to 8-9, precipitate for 40 min, and age for 8 h after precipitation to obtain slurry I; dissolve 36.3 g Cu(NO3)2·3H2O, 80.9 g Zr(NO3)4·5H2O and 46.3 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 80℃, slowly add KOH solution, control the pH to 10-11, precipitate for 40 min, and age for 8 h after precipitation to obtain slurry II;

[0049] (2) Mix the slurry I and slurry II after aging and continue aging in a water bath at 80°C for 8 hours. After aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000 μs / cm, dry the filter cake at 110°C for 12 hours, and calcine it at 800°C for 4 hours to obtain a solid mixture.

[0050] (3) Dissolve 1.5g Ba(NO3)2 in 15mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 150℃, and calcine at 500℃ for 4h to obtain catalyst G3. XRF analysis showed that, by weight percentage, the content of CuO was 23.9%, ZrO2 was 23.2%, ZnO was 21.9%, Cr2O3 was 30.1%, and BaO was 0.9%; N2 adsorption-desorption analysis showed a specific surface area of ​​81.0 m² / s. 2 / g.

[0051] Catalytic dehydrogenation of 1,4-butanediol:

[0052] Catalyst G3 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 250 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature was lowered to 200 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LHSV) of 0.5 h⁻¹. -1 The reaction pressure was 0.3 MPa, and the hydrogen-to-ethanol molar ratio was 10. After 3 hours of stabilization, the BDO conversion was 98.7%, the GBL selectivity was 98.3%, and the yield was 97.0%.

[0053] Example 4

[0054] Catalyst preparation:

[0055] (1) Prepare a 2 mol / L Na2CO3 solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 29.3 g Cu(NO3)2·3H2O and 63.2 g Zn(NO3)2·6H2O in 200 mL of deionized water, stir continuously in a constant temperature water bath at 40℃, slowly add Na2CO3 solution, control the pH to 8-9, precipitate for 40 min, and age for 12 h after precipitation to obtain slurry I; dissolve 58.6 g Cu(NO3)2·3H2O, 61.4 g Zr(NO3)4·5H2O and 53 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 40℃, slowly add Na2CO3 solution, control the pH to 10-11, precipitate for 40 min, and age for 12 h after precipitation to obtain slurry II;

[0056] (2) Mix the slurry I and slurry II after aging and continue aging in a 40℃ water bath for 12h; after aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000μs / cm, dry the filter cake at 110℃ for 12h, and calcine it at 650℃ for 4h to obtain a solid mixture.

[0057] (3) Dissolve 8.8 g of LiNO3 in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 140 °C, and calcine at 350 °C for 4 h to obtain catalyst G4. XRF analysis showed that, by weight percentage, the content of CuO was 28.9%, ZrO2 was 17.6%, ZnO was 17.2%, Cr2O3 was 34.4%, and Li2O was 1.9%; N2 adsorption-desorption analysis showed a specific surface area of ​​93.1 m². 2 / g.

[0058] Catalytic dehydrogenation of 1,4-butanediol:

[0059] Catalyst G4 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 230 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature was lowered to 190 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LHSV) of 0.2 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the hydrogen-to-ethanol molar ratio was 15. After 3 hours of stabilization, the BDO conversion was 99.9%, the GBL selectivity was 99.4%, and the yield was 99.3%.

[0060] Example 5

[0061] Catalyst preparation:

[0062] (1) Prepare a 2 mol / L NaHCO3 solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 28.9 g Cu(NO3)2·3H2O and 88.5 g Zn(NO3)2·6H2O in 200 mL of deionized water, continuously stir in a constant temperature water bath at 30℃, slowly add NaHCO3 solution, control the pH to 8-9, precipitate for 40 min, and age for 12 h after precipitation to obtain slurry I; dissolve 86.8 g Cu(NO3)2·3H2O, 50.9 g Zr(NO3)4·5H2O and 38.2 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 30℃, slowly add NaHCO3 solution, control the pH to 10-11, precipitate for 40 min, and age for 12 h after precipitation to obtain slurry II;

[0063] (2) Mix the slurry I and slurry II after aging and continue aging in a 30℃ water bath for 12h; after aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000μs / cm, dry the filter cake at 110℃ for 12h, and calcine it at 500℃ for 4h to obtain a solid mixture.

[0064] (3) Dissolve 2.8 g of LiNO3 in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 120 °C, and calcine at 400 °C for 4 h to obtain catalyst G5. XRF analysis showed that, by weight percentage, the content of CuO was 38.1%, ZrO2 was 14.6%, ZnO was 24.1%, Cr2O3 was 22.6%, and Li2O was 0.6%; N2 adsorption-desorption analysis showed a specific surface area of ​​82.4 m². 2 / g.

[0065] Catalytic dehydrogenation of 1,4-butanediol:

[0066] Catalyst G5 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 240 °C for 4 h in a hydrogen atmosphere. After reduction, the temperature was lowered to 210 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the hydrogen-to-ethanol molar ratio was 8. After 3 hours of stabilization, the BDO conversion was 99.6%, the GBL selectivity was 99.0%, and the yield was 98.6%.

[0067] Example 6

[0068] Catalyst preparation:

[0069] (1) Prepare a 2 mol / L KHCO3 solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 19.8 g Cu(NO3)2·3H2O and 63.9 g Zn(NO3)2·6H2O in 200 mL of deionized water, continuously stir in a constant temperature water bath at 30℃, slowly add KHCO3 solution, control the pH to 8-9, precipitate for 40 min, and age for 8 h after precipitation to obtain slurry I; dissolve 79.3 g Cu(NO3)2·3H2O, 99.1 g Zr(NO3)4·5H2O and 34.3 g Cr2H4Na2O9 in 200 mL of deionized water, slowly add KHCO3 solution dropwise under constant temperature water bath and stirring conditions at 50℃, control the pH to 10-11, precipitate for 40 min, and age for 8 h after precipitation to obtain slurry II;

[0070] (2) Mix the slurry I and slurry II after aging and continue aging in a water bath at 40°C for 8 hours. After aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000 μs / cm, dry the filter cake at 110°C for 12 hours, and calcine it at 800°C for 4 hours to obtain a solid mixture.

[0071] (3) Dissolve 8.3 g Mg(NO3)2 in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 120 °C, and calcine at 400 °C for 4 h to obtain catalyst G6. XRF analysis showed that, by weight percentage, the content of CuO was 32.6%, ZrO2 was 28.4%, ZnO was 17.4%, Cr2O3 was 20.3%, and MgO was 1.3%; N2 adsorption-desorption analysis showed a specific surface area of ​​93.8 m². 2 / g.

[0072] Catalytic dehydrogenation of 1,4-butanediol:

[0073] Catalyst G6 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 270 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature was lowered to 180 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LHSV) of 1 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the hydrogen-to-ethanol molar ratio was 6. After 3 hours of stabilization, the BDO conversion was 98.4%, the GBL selectivity was 99.8%, and the yield was 98.2%.

[0074] Example 7

[0075] Catalyst preparation:

[0076] (1) Ammonia solution with a concentration of 25% was used as a precipitant. Under constant temperature water bath and stirring conditions at 50℃, 23.0g Cu(NO3)2·3H2O and 61.0g Zn(NO3)2·6H2O were dissolved in 200mL of deionized water. The mixture was stirred continuously in a constant temperature water bath at 50℃. Ammonia solution was slowly added to the mixture. The pH was controlled at 8-9. The precipitation reaction was carried out for 40min. After precipitation, the mixture was aged for 12h to obtain slurry I. 57.5g Cu(NO3)2·3H2O, 103.6g Zr(NO3)4·5H2O and 42.5g Cr2H4Na2O9 were dissolved in 200mL of deionized water. Under constant temperature water bath and stirring conditions at 50℃, ammonia solution was slowly added dropwise. The pH of precipitation was controlled at 10-11. The precipitation reaction was carried out for 40min. After precipitation, the mixture was aged for 12h to obtain slurry II.

[0077] (2) Mix the slurry I and slurry II after aging and continue aging in a 50℃ water bath for 12h; after aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000μs / cm, dry the filter cake at 110℃ for 12h, and calcine it at 700℃ for 4h to obtain a solid mixture.

[0078] (3) Dissolve 5.8 g of NaNO3 in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 120 °C, and calcine at 400 °C for 4 h to obtain catalyst G7. XRF analysis showed that, by weight percentage, the content of CuO was 26.5%, ZrO2 was 29.7%, ZnO was 16.6%, Cr2O3 was 25.1%, and Na2O was 2.1%; N2 adsorption-desorption analysis showed a specific surface area of ​​94.2 m². 2 / g.

[0079] Catalytic dehydrogenation of 1,4-butanediol:

[0080] Catalyst G7 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 270 °C for 4 h in a hydrogen atmosphere. After reduction, the temperature was lowered to 240 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 4 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the hydrogen-to-ethanol molar ratio was 5. After 3 hours of stabilization, the BDO conversion was 95.2%, the GBL selectivity was 99.9%, and the yield was 95.1%.

[0081] Example 8

[0082] Catalyst preparation:

[0083] (1) Prepare a 2 mol / L K2CO3 solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 16.3 g Cu(NO3)2·3H2O and 67.9 g Zn(NO3)2·6H2O in 200 mL of deionized water, continuously stir in a constant temperature water bath at 50℃, slowly add K2CO3 solution, control the pH to 8-9, precipitate for 40 min, and age for 12 h after precipitation to obtain slurry I; dissolve 81.5 g Cu(NO3)2·3H2O, 87.9 g Zr(NO3)4·5H2O and 36.0 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 50℃, slowly add K2CO3 solution, control the pH to 10-11, precipitate for 40 min, and age for 12 h after precipitation to obtain slurry II;

[0084] (2) Mix the slurry I and slurry II after aging and continue aging in a 50℃ water bath for 12h; after aging, filter the mother liquor, wash it with deionized water until the conductivity is less than 1000μs / cm, dry the filter cake at 110℃ for 12h, and calcine it at 700℃ for 4h to obtain a solid mixture.

[0085] (3) Dissolve 11.8 g of Ca(NO3)2 in 15 mL of deionized water, impregnate the solid mixture obtained in step (2), dry at 120 °C, and calcine at 380 °C for 4 h to obtain catalyst G8. XRF analysis showed that, by weight percentage, the content of CuO was 32.2%, ZrO2 was 25.2%, ZnO was 18.5%, Cr2O3 was 21.3%, and CaO was 2.8%; N2 adsorption-desorption analysis showed a specific surface area of ​​95.1 m². 2 / g.

[0086] Catalytic dehydrogenation of 1,4-butanediol:

[0087] Catalyst G8 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was filled into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation reaction. Before the reaction, the catalyst was used as a precipitant in a hydrogen atmosphere at 300 °C. The catalyst was prepared using a co-precipitation method. Copper, zirconium, and zinc salts were mixed, and Na₂CO₃ solution was added to the mixed salt under stirring and a 70 °C constant temperature water bath. The pH was adjusted to 7-7.5, and stirring was stopped after the addition was complete. The reaction mixture was allowed to stand at 70 °C for 30 min, and then at room temperature for 20 h. After aging, the mother liquor was filtered and calcined at 350 °C for 4 h to obtain catalyst D4. XRF analysis showed that, by weight percentage, the CuO content was 47.1%, the ZrO₂ content was 14.6%, and the ZnO content was 38.4%. N₂ adsorption-desorption analysis showed a specific surface area of ​​81.4 m². 2 / g.

[0088] Catalyst D4 was compressed into tablets, crushed, and 10 mL of the resulting 20-28 mesh sample was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 270 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature was lowered to 200 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction pressure was 0.07 MPa, and the hydrogen-to-ethanol molar ratio was 5. After 3 hours of stabilization, the BDO conversion was 93.1%, the GBL selectivity was 99.4%, and the yield was 92.5%.

[0089] Comparative Example 5

[0090] Catalyst preparation:

[0091] (1) Prepare a 2 mol / L KOH solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 82.3 g Cu(NO3)2·3H2O, 81.2 g Zn(NO3)2·6H2O, 86.8 g Zr(NO3)4·5H2O and 37.3 g Cr2H4Na2O9 in 400 mL of deionized water, stir continuously in a constant temperature water bath at 40℃, slowly add KOH solution, control the pH to 8-9, precipitate reaction for 40 min, after precipitation is completed, age for 4 h, after aging, filter the mother liquor, wash with deionized water until the conductivity is less than 1000 μs / cm, dry the filter cake at 110℃ for 12 h, and calcine at 500℃ for 4 h to obtain a solid mixture;

[0092] (2) Dissolve 5.9 g of Ca(NO3)2·4H2O in 15 mL of deionized water, impregnate the solid mixture obtained in step (1), dry at 110 °C, and calcine at 380 °C for 4 h to obtain catalyst D5. XRF analysis showed that, by weight percentage, the content of CuO was 27.3%, ZrO2 was 25.0%, ZnO was 22.4%, Cr2O3 was 23.9%, and CaO was 1.4%. N2 adsorption-desorption analysis showed a specific surface area of ​​58.4 m². 2 / g.

[0093] Catalytic dehydrogenation of 1,4-butanediol:

[0094] Catalyst D5 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a stainless steel tubular fixed-bed reactor with an inner diameter of 20 mm and a length of 500 mm for dehydrogenation reaction. Before the reaction, XRF analysis showed that the catalyst contained 54.2% CuO, 26.7% ZrO2, and 19.1% Cr2O3 by weight; N2 adsorption-desorption analysis showed a specific surface area of ​​46.1 m². 2 / g.

[0095] Catalyst D2 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 280 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature was lowered to 200 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction pressure was 0.15 MPa, and the hydrogen-to-ethanol molar ratio was 7. After 3 hours of stabilization, the BDO conversion was 90.2%, the GBL selectivity was 98.1%, and the yield was 88.5%.

[0096] Comparative Example 3

[0097] Preparation of CuO / ZrO / Cr2O3 / ZnO catalyst:

[0098] 88.7 g of Cu(NO3)2·3H2O, 87.5 g of Zr(NO3)4·5H2O, 80.4 g of Zn(NO3)2·6H2O, and 36.6 g of Cr2H4Na2O9 were dissolved in 200 mL of deionized water to prepare corresponding soluble salt solutions. A 2 mol / L KOH solution was prepared as a precipitant. The catalyst was prepared by co-precipitation. Copper, zirconium, and zinc salts were added to the mixed salt solution under stirring and a constant temperature water bath at 80 °C. The pH was adjusted to 8–9, the precipitation time was controlled at 40 min, and the aging time was 2 h. After aging, the mother liquor was filtered and washed with deionized water until the conductivity was less than 1000 μS / cm. The filter cake was dried at 110℃ for 12 h and calcined at 500℃ for 4 h to obtain catalyst D3. XRF analysis showed that, by weight percentage, the content of CuO was 29.2%, ZrO2 was 25.1%, ZnO was 21.9%, and Cr2O3 was 23.8%. N2 adsorption-desorption analysis showed that the specific surface area was 51.3 m². 2 / g.

[0099] Catalyst D3 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 280 °C for 4 h in a hydrogen atmosphere. After reduction, the temperature was lowered to 200 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction pressure was 0.15 MPa, and the hydrogen-to-ethanol molar ratio was 10. After 3 hours of stabilization, the BDO conversion was 91.8%, the GBL selectivity was 99.6%, and the yield was 91.4%.

[0100] Comparative Example 4

[0101] 48.3 g of Cu(NO3)2·3H2O, 17.2 g of Zr(NO3)4·5H2O, and 47.6 g of Zn(NO3)2·6H2O were dissolved in 200 mL of deionized water to prepare corresponding soluble salt solutions. A 1.5 mol / L Na2CO3 solution was then prepared for reduction over 4 h. After reduction, the temperature was lowered to 180 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 2 h⁻¹. -1 The reaction pressure was 0.2 MPa, and the hydrogen-to-ethanol molar ratio was 5. After 3 hours of stabilization, the BDO conversion was 98.1%, the GBL selectivity was 99.9%, and the yield was 98.0%.

[0102] Comparative Example 1

[0103] Preparation of CuO / ZnO catalyst:

[0104] 200g of Cu(NO3)2·3H2O and 125.6g of Zn(NO3)2·6H2O were dissolved in 200mL of deionized water to prepare corresponding soluble salt solutions. A 2mol / L KOH solution was prepared as a precipitant. The catalyst was prepared by co-precipitation. Copper and zinc salts were mixed under stirring and an 80℃ constant temperature water bath. KOH solution was added to the mixed salts, the pH was adjusted to 8-9, the precipitation time was controlled at 40min, and the aging time was 2h. After aging, the mother liquor was filtered, washed with deionized water until the conductivity was less than 1000μs / cm, and the filter cake was dried at 110℃ for 12h and calcined at 500℃ for 4h to obtain catalyst D1. XRF analysis showed that, by weight percentage, the CuO content was 65.8% and the ZnO content was 34.2%. N2 adsorption-desorption analysis showed a specific surface area of ​​37.9m². 2 / g.

[0105] Catalytic dehydrogenation of 1,4-butanediol:

[0106] Catalyst D1 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a 20 mm inner diameter stainless steel tubular fixed-bed reactor for dehydrogenation. Before the reaction, the catalyst was reduced at 280 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature was lowered to 200 °C, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LHSV) of 1 h⁻¹. -1 The reaction pressure was 0.15 MPa, and the hydrogen-to-ethanol molar ratio was 7. After 3 hours of stabilization, the BDO conversion was 87.5%, the GBL selectivity was 97.7%, and the yield was 85.5%.

[0107] Comparative Example 2

[0108] Preparation of CuO / ZrO / Cr2O3 catalyst:

[0109] 164.7 g of Cu(NO3)2·3H2O, 93.1 g of Zr(NO3)4·5H2O, and 29.4 g of Cr2H4Na2O9 were dissolved in 200 mL of deionized water to prepare corresponding soluble salt solutions. A 2 mol / L KOH solution was prepared as a precipitant. The catalyst was prepared by co-precipitation. Copper, zirconium, and chromium salts were mixed with KOH solution under stirring and a constant temperature water bath at 80 °C. The pH was adjusted to 8–9, the precipitation time was controlled at 40 min, and the aging time was 2 h. After aging, the mother liquor was filtered, washed with deionized water until the conductivity was less than 1000 μS / cm, dried at 110 °C for 12 h, and calcined at 500 °C for 4 h to obtain catalyst D2. It was then reduced at 280 °C for 4 h under a hydrogen atmosphere. After reduction, the temperature is lowered to 200°C, and the feedstock 1,4-butanediol (BDO) is introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹.-1 The reaction pressure was 0.15 MPa, and the hydrogen-to-ethanol molar ratio was 7. After 3 hours of stabilization, the BDO conversion was 84.8%, the GBL selectivity was 98.4%, and the yield was 83.4%.

[0110] Comparative Example 6

[0111] Catalyst preparation:

[0112] (1) Prepare a 2 mol / L KOH solution; under constant temperature water bath and stirring conditions at 40℃, dissolve 27.8 g Cu(NO3)2·3H2O and 81.2 g Zn(NO3)2·6H2O in 200 mL of deionized water, stir continuously in a constant temperature water bath at 40℃, slowly add KOH solution, control the pH to 8-9, precipitate for 40 min, and age for 2 h after precipitation to obtain slurry I; dissolve 55.5 g Cu(NO3)2·3H2O, 86.8 g Zr(NO3)4·5H2O and 37.3 g Cr2H4Na2O9 in 200 mL of deionized water respectively, under constant temperature water bath and stirring conditions at 40℃, slowly add KOH solution, control the pH to 10-11, precipitate for 40 min, and age for 2 h after precipitation to obtain slurry II;

[0113] (2) After aging, slurry I and slurry II were mixed and aged continuously in a 40℃ water bath for 2 hours. After aging, the mother liquor was filtered and washed with deionized water until the conductivity was less than 1000 μS / cm. The filter cake was dried at 110℃ for 12 hours and calcined at 500℃ for 4 hours to obtain catalyst D6. XRF analysis showed that, by weight percentage, the CuO content was 27.7%, the ZrO2 content was 25.4%, the ZnO content was 22.7%, and the Cr2O3 content was 24.2%. N2 adsorption-desorption analysis showed that the specific surface area was 84.6 m². 2 / g.

[0114] Catalytic dehydrogenation of 1,4-butanediol:

[0115] Catalyst G1 was compressed into tablets, crushed, and 10 mL of 20-28 mesh was packed into the isothermal zone of a stainless steel tubular fixed-bed reactor with an inner diameter of 20 mm and a length of 500 mm for dehydrogenation reaction. Before the reaction, the catalyst was reduced at 280℃ for 4 h in a hydrogen atmosphere. After reduction, the temperature was lowered to 200℃, and the feedstock 1,4-butanediol (BDO) was introduced at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction pressure was 0.15 MPa, and the hydrogen-to-ethanol molar ratio was 7. After 3 hours of stabilization, the BDO conversion was 99.5%, the GBL selectivity was 97.8%, and the yield was 97.3%.

Claims

1. A method for preparing a dehydrogenation catalyst, comprising the following steps: (1) Add a precipitant to a mixed solution of soluble copper salt and soluble zinc salt, stir and react, and age to obtain slurry I; add a precipitant to a mixed solution of soluble copper salt, soluble chromate and soluble zirconium salt, stir and react, and age to obtain slurry II; (2) Mix slurry I and slurry II, stir and react, age, and then filter, wash, dry and calcin to obtain a solid mixture; (3) Prepare a solution with a salt containing element M, impregnate the solid mixture obtained in step (2), dry, calcine, and press into tablets to obtain the dehydrogenation catalyst; the element M is selected from at least one of Li, Na, K, Ca, Mg and Ba; The amount of each raw material fed is based on the following composition of the catalyst: 20-40% copper oxide, 15-30% zinc oxide, 20-40% chromium oxide, 15-30% zirconium oxide, and 0.2-3.0% oxide of M; among which, based on the total amount of copper, the ratio of copper in slurry I and slurry II is 1:1-1:

5.

2. The preparation method according to claim 1, characterized in that, The reaction temperature after adding the precipitant in step (1) is 25-80℃, and the stirring reaction time is 1-10 hours.

3. The preparation method according to claim 1, characterized in that, The soluble copper salt, soluble zinc salt, and soluble zirconium salt mentioned in step (1) are selected from at least one of soluble nitrates, chlorides, acetates, and sulfates, and the soluble chromate is at least one of sodium chromate and sodium dichromate.

4. The preparation method according to claim 1, characterized in that, The precipitant in step (1) is selected from at least one of the following: ammonia, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate and potassium hydroxide aqueous solution.

5. The preparation method according to claim 1, characterized in that, The aging conditions described in step (1) are a temperature of 25-80℃ and an aging time of 2-12h.

6. The preparation method according to claim 1, characterized in that, In step (2), the ratio of copper in slurry I and slurry II is 1:1 to 1:

3.

7. The preparation method according to claim 1, characterized in that, In step (2), the aging conditions are: temperature 25-80℃ and aging time 2-12h.

8. The preparation method according to claim 1, characterized in that, The drying temperature in step (2) is 110-150℃ and the time is 4-12h; the calcination temperature is 300-800℃ and the time is 2-8h.

9. The preparation method according to claim 1, characterized in that, The drying temperature in step (3) is 110-150℃ and the time is 4-12h; the calcination temperature is 300-600℃ and the time is 2-8h.

10. The dehydrogenation catalyst prepared by the preparation method according to any one of claims 1-9.

11. A method for preparing γ-butyrolactone by dehydrogenation of 1,4-butanediol, wherein 1,4-butanediol is reacted with the catalyst of claim 10 to obtain γ-butyrolactone.

12. The method according to claim 11, characterized in that, Before the reaction, the dehydrogenation catalyst is first reduced in a hydrogen-containing atmosphere at 150-320°C.

13. The method according to claim 11, characterized in that, The dehydrogenation reaction was carried out in a fixed-bed reactor under the following conditions: reaction temperature 180-260℃, reaction pressure 0.01-0.3 MPaG, and liquid hourly space velocity 0.2-5 h⁻¹. -1 The molar ratio of H2 to BDO is 2-20.

14. The method according to claim 13, characterized in that, The reaction temperature for the dehydrogenation reaction is 180-220℃.