Copper-based catalyst for alcohol dehydrogenation reaction as well as preparation method and application of copper-based catalyst

Abstract

The invention discloses a copper-based catalyst for alcohol dehydrogenation reaction as well as a preparation method and application of the copper-based catalyst. The catalyst comprises: (a) an active metal Cu; (b) a carrier SiO2; (c) an auxiliary agent; the auxiliary agent is prepared from one or more of ZrO2, CeO2, ZnO and La2O3; the particle size of the active metal Cu in the component (a) is 2-5nm; the surface acidity of the catalyst is less than 0.01 mmol / g on the basis of adsorbate. The catalyst is used in alcohol dehydrogenation reaction, and has the characteristics of high dehydrogenation conversion rate, high target product selectivity, long service life and good stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a copper-based catalyst for alcohol dehydrogenation reactions, its preparation method, and its application. Background Technology

[0002] Alcohol dehydrogenation is an important organic synthesis method used to prepare aldehydes, ketones, esters, and other organic compounds. Traditional methods often employ toxic metal catalysts (e.g., Cr-containing catalysts) or require high-energy oxidants to accelerate the process; however, these methods often pose environmental and safety risks. In recent years, copper-based catalysts, especially Cu / SiO2 catalysts supported on silica (SiO2), have attracted considerable attention due to their excellent catalytic performance in gas-phase alcohol dehydrogenation reactions and have been applied in various gas-phase oxygen-free dehydrogenation reactions to prepare aldehydes. The SiO2 support possesses diverse and easily tunable spatial textures, providing highly dispersed copper active sites and contributing to catalyst structure stability. This type of catalyst exhibits good activity and selectivity in alcohol dehydrogenation reactions while maintaining low cost. On the other hand, while copper-based catalysts demonstrate many advantages in alcohol dehydrogenation reactions, they also face several challenges and difficulties that need to be addressed. Cu is a metal with a low melting point and is more sensitive to temperature than other metals. During the catalytic reaction, the nano-copper particles originally dispersed on the support surface gradually undergo thermal migration and aggregation, fusing into larger metal particles, thus reducing the surface area of ​​active Cu. Therefore, Cu aggregation and sintering is an important cause of catalyst deactivation. In addition, the reconstruction and loss of the support under the scouring of organic alcohol vapors also significantly weakens the interaction between the support and the metal, causing changes in the catalyst structure and loss of catalytic performance, hindering the long-term operation of the production unit.

[0003] CN102247854A discloses a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone and its preparation method. The catalyst uses CuO, ZnO, and ZrO2 as the main active components and M2O as the catalyst modifier. This catalyst improves the selectivity of cyclohexanone in the dehydrogenation of cyclohexanol. However, it suffers from low conversion rate and poor stability. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a copper-based catalyst for alcohol dehydrogenation reactions, its preparation method, and its application. This catalyst, when used in alcohol dehydrogenation reactions, features uniform dispersion of active metal, high utilization rate, high selectivity for target products, excellent structural stability, and long cycle life. Furthermore, the application process conditions are easy to achieve, significantly reducing the start-up cost of alcohol dehydrogenation reactions.

[0005] A first aspect of the present invention provides a copper-based catalyst for alcohol dehydrogenation reactions. The catalyst comprises:

[0006] (a) Active metal Cu;

[0007] (b) Support SiO2;

[0008] (c) Additives; said additives include one or more of ZrO2, CeO2, ZnO, and La2O3;

[0009] The particle size of component (a) active metal Cu is 2-5 nm; the catalyst, based on adsorbate, has a surface acidity of less than 0.01 mmol / g, preferably greater than or equal to 0.001 mmol / g and less than 0.01 mmol / g.

[0010] According to the present invention, more preferably, the catalyst comprises, based on the mass of the catalyst, the catalyst comprising:

[0011] (a) 15 wt% to 30 wt% of active metal Cu, calculated as CuO;

[0012] (b) 40 wt% to 58 wt% of support SiO2, based on SiO2;

[0013] (c) 20 wt% to 45 wt% of additives, based on metal oxides.

[0014] According to the present invention, the particle size of component (a) active metal Cu is 2–5 nm. The specific surface area of ​​component (a) active metal Cu is 30–70 m². 2 / g. After 500h of dehydrogenation reaction, the Cu grain size increased by 30%–96%.

[0015] According to the present invention, both the (b) support SiO2 and the (c) additive are amorphous structures.

[0016] According to the present invention, the catalyst has a surface acidity of less than 0.01 mmol / g, preferably greater than or equal to 0.001 mmol / g and less than 0.01 mmol / g, based on the adsorbate.

[0017] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst. The method includes:

[0018] (1) Disperse the auxiliary agent source and silicon source in an organic alcohol, and then add ammonia water to react; calcine the solid after the reaction;

[0019] (2) The calcination product from step (1) is dispersed in a copper ammonia solution and subjected to hydrothermal reaction and calcination to obtain the catalyst.

[0020] According to the present invention, in step (1), the auxiliary agent source is a salt containing the metal element of the auxiliary agent, preferably at least one of nitrate, acetate, sulfate, and chloride. The silicon source is at least one of tetraethyl orthosilicate (TEOS) and silica sol. The organic alcohol is at least one of methanol, ethanol, and isopropanol.

[0021] According to the present invention, in step (1), the volume ratio of organic alcohol to silicon source is 1:1 to 10:1.

[0022] According to the present invention, in step (1), the mass concentration of ammonia water is 10wt% to 25wt%. Preferably, the ammonia water is added dropwise. The dropping time of the ammonia water is 10 to 60 minutes. The amount of ammonia water added is adjusted to make the pH value of the reaction solution 10 to 12.

[0023] According to the present invention, in step (1), the reaction conditions are: reaction time 2-8 h, reaction temperature 10-60 °C. The reaction is carried out under stirring.

[0024] According to the present invention, in step (1), the calcination conditions are: calcination temperature of 200–500°C and calcination time of 2–8 h. Drying can be performed before calcination. Preferably, the drying conditions are: drying time of 12–36 h and drying temperature of 80–120°C.

[0025] According to the present invention, in step (2), the molar concentration of copper in the copper ammonia solution is 0.5–5 mol / L. Further, the copper ammonia solution is a tetraamminecopper ion solution, preferably a tetraamminecopper nitrate solution.

[0026] According to the present invention, in step (2), the hydrothermal reaction is carried out in an autoclave. That is, the reaction solution is placed in the autoclave, and then the autoclave is placed in a heating device. The heating device is preferably an oven. The conditions for the hydrothermal reaction are: temperature 160-240°C, time 24-48 h. The pressure is not particularly limited, and the pressure is autogenous pressure.

[0027] According to the present invention, in step (2), the calcination conditions are: calcination temperature of 300-600℃ and calcination time of 2-8h. Washing and drying can be performed before calcination. The drying conditions are: drying temperature of 80-120℃ and drying time of 12-36h.

[0028] A third aspect of the present invention provides the application of the above-described catalyst in alcohol dehydrogenation reactions. This application can be used to prepare aldehydes and / or ketones from alcohols through dehydrogenation.

[0029] According to the present invention, the catalyst is used for reduction before the alcohol dehydrogenation reaction, preferably high-temperature gas-phase reduction. The reducing gas is H2 and / or CO. The reduction conditions are: temperature 180–300°C, time 2–6 h, and pressure 0.1–3 MPa.

[0030] According to the present invention, the reaction conditions for the alcohol dehydrogenation reaction are as follows: reaction temperature of 120–300°C and reaction pressure of 0.02–0.5 MPa. The reaction atmosphere is a reducing atmosphere, preferably a mixture of hydrogen and nitrogen. Further, the volume ratio of nitrogen to hydrogen is 0.2–10:1. The molar ratio of alcohol to hydrogen is 1:0.2–5. The alcohol is at least one selected from diethylene glycol, 1,4-butanediol, isopropanol, n-pentanol, and cyclohexanol. The liquid hourly space velocity (LHSV) of the alcohol feedstock is 0.05–5 h⁻¹. -1 .

[0031] Compared with the prior art, the advantages of this invention are as follows:

[0032] (1) The catalyst of the present invention comprises: (a) an active metal Cu; (b) a support SiO2; and (c) an auxiliary agent; wherein the auxiliary agent comprises one or more of ZrO2, CeO2, ZnO, and La2O3; the particle size of component (a) the active metal Cu is 2–5 nm; and the surface acidity of the catalyst, based on adsorbate, is less than 0.01 mmol / g. The active metal of the catalyst is uniformly dispersed, has high utilization rate, excellent structural stability, and a long lifespan.

[0033] (2) The preparation method of the catalyst of the present invention includes: (1) dispersing the auxiliary source and silicon source in an organic alcohol, and then adding ammonia water to react; calcining the solid after reaction; (2) dispersing the calcined product of step (1) in a copper ammonia solution, performing hydrothermal reaction and calcination to obtain the catalyst. This method adjusts the structural properties of the catalyst by doping with structural auxiliary agents and hydrothermal treatment, promotes the uniform dispersion of auxiliary agents with amorphous structures on the support, greatly increases the contact probability and interface strength with active metals, enhances the energy barrier for metal migration and auxiliary agent aggregation, and promotes the interaction between metal and support, so that the catalyst has uniformly dispersed metal active components, high utilization rate and large active surface area. The auxiliary agent adjustment also reduces the acidity of the catalyst surface and reduces the occurrence of side reactions. The active metal particles are small in size and have strong thermal stability, ensuring high catalytic dehydrogenation conversion rate and selectivity. After long-term high-temperature reaction, the size of the active metal is not easy to grow due to aggregation. The overall structure of the catalyst is stable and the catalytic life is long, which has good prospects for industrial application.

[0034] The raw materials used in the method of this invention are simple and readily available, low in cost, environmentally friendly, and easy to prepare, allowing for large-scale production.

[0035] (3) In the application of the catalyst of the present invention, the catalyst is used in the dehydrogenation reaction of alcohols and has the characteristics of high dehydrogenation conversion rate, high selectivity of target products aldehydes / ketones, long catalyst life and good stability. Attached Figure Description

[0036] Figure 1 The XRD patterns of the catalysts after reduction in Example 1 and Comparative Example 2 of this invention are shown. Detailed Implementation

[0037] To better understand the present invention, some embodiments are provided below to further illustrate the invention in detail. However, these embodiments should not be considered as limitations on the present invention.

[0038] In this invention, after condensation and separation, the reaction products are analyzed by gas chromatography to determine the composition of the products and calculate the conversion rate of the alcohol and the selectivity (i.e., dehydrogenation selectivity) of the target product aldehyde or ketone. Both the alcohol conversion rate and the selectivity of the target product are expressed as mass percentages. The specific formulas are as follows:

[0039] Alcohol conversion rate wt% = (mass of alcohol feedstock - mass of alcohol in product) / mass of alcohol feedstock * 100%;

[0040] Aldehyde selectivity wt% = mass of aldehyde in product / (mass of alcohol feedstock - mass of alcohol in product) * 100%;

[0041] Ketone selectivity wt% = mass of ketone in product / (mass of alcohol feedstock - mass of alcohol in product) * 100%.

[0042] In this invention, the Cu particle size was calculated using the Scherrer formula based on XRD data. The XRD data were measured using a Philip X'pert Pro diffractometer. The X-ray source was Cu target Kα rays (λ = 0.15408 nm) filtered by a Ni filter, with a sampling step size of 0.06° / s, an X-ray tube operating voltage of 40 kV, and a current of 40 mA.

[0043] In this invention, the Cu grain size growth rate % = (Cu particle size of catalyst after 500h reaction - Cu particle size of fresh catalyst) / Cu particle size of fresh catalyst * 100%.

[0044] In this invention, the specific surface area and pore structure properties of the samples were tested using a Micromeritics ASAP-3020 physical adsorption instrument. Before testing, the samples were degassed at 300°C for 3 hours, and the tests were conducted at liquid nitrogen temperature (-196°C). The specific surface area of ​​the samples was calculated using the Brunauer-Emmett-Teller (BET) multilayer physical adsorption model.

[0045] In this invention, the surface acidity of the catalyst was determined by chemisorption. The 10 vol% NH3 / Ar adsorption was performed on a BELCAT II, ​​MicrotracBEL instrument. Before testing, the sample was first purged in Ar at 200°C for 2 h, then cooled to 100°C, and 10 vol% NH3 / Ar was adsorbed onto the sample for 30 min. Subsequently, Ar purging was resumed for 1 h. The TPD curve was collected from 100°C to 600°C at a heating rate of 5°C / min.

[0046] In this invention, the specific surface area of ​​catalyst component (a) active metal Cu was determined by N2O chemical titration. The catalyst containing M g of copper was reduced at 250°C in a hydrogen atmosphere for 1 h, then cooled to 50°C. N2O pulsed injection adsorption was used, and the amount of N2O consumed was recorded as V ml. The copper atom density was taken as 1.46 × 10⁻⁶. 19 pcs / m 2 Then the specific surface area S = (V × 10 -3 ×N A ) / (22.4×1.46×10 19 ×M), where N A is Avogadro's constant.

[0047] In this invention, the copper ammonia solution in each example is a tetraamminecopper nitrate solution.

[0048] Example 1

[0049] (1) Weigh 15.7 g of cerium nitrate hexahydrate and 24.2 mL of tetraethyl orthosilicate (TEOS), dissolve them in 100 mL of ethanol solution, and stir to mix thoroughly. Then, add 20 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 20 min. Stir at 20 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0050] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 2 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 17%, CeO2 40.5%, SiO2 42.5%.

[0051] The catalyst is reduced before application. The reduction method is as follows: reduction at 300℃ and 0.1MPa in an H2 atmosphere for 2 hours. The XRD pattern of the reduced catalyst is shown below. Figure 1 Both the carrier SiO2 and the additives exist in an amorphous, non-crystalline structure, which is reflected in the XRD spectrum by the absence of additional diffraction peaks other than those of the active metal.

[0052] The method for testing the alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 5:1. The system pressure is adjusted to 0.1 MPa and the temperature to 260℃. The raw material is introduced into the reactor to carry out the dehydrogenation reaction according to a diethylene glycol-to-hydrogen molar ratio of 1:1. The liquid hourly space velocity (LHSV) of diethylene glycol is 1 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. The test results are shown in Table 1.

[0053] Example 2

[0054] (1) Weigh 14.6 g of zinc nitrate hexahydrate and 24.2 mL of tetraethyl orthosilicate (TEOS), dissolve them in 100 mL of ethanol solution, and stir to mix thoroughly. Then, add 20 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 20 min. Stir at 25 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0055] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 2 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 20%, ZnO 30%, SiO2 50%.

[0056] The catalyst is reduced before application. The reduction method is as follows: reduction at 300℃ and 0.2MPa in an H2 atmosphere for 2 hours. In the XRD pattern of the reduced catalyst, no additional diffraction peaks appear besides the active metal. That is, both the SiO2 support and the promoter exist as amorphous structures.

[0057] The test method for alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 3:1. The system pressure is adjusted to 0.1 MPa and the temperature to 180℃. The raw material is introduced into the reactor for dehydrogenation reaction according to a 1:1 molar ratio of 1,4-butanediol to hydrogen. The liquid hourly space velocity (LHSV) of 1,4-butanediol is 1 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. The test results are shown in Table 1.

[0058] Example 3

[0059] (1) Weigh 8.7 g of zirconium nitrate pentahydrate and 24.2 mL of tetraethyl orthosilicate (TEOS), dissolve them in 100 mL of ethanol solution, and stir to mix evenly. Then, add 20 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 20 min. Stir at 30 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0060] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 2 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 22.5%, ZrO2 21.5%, SiO2 56.0%.

[0061] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was: reduction at 300℃ and 1.0 MPa in an H2 atmosphere for 2 hours. In the XRD pattern of the reduced catalyst, no additional diffraction peaks appeared besides the active metal. That is, both the SiO2 support and the promoter exist as amorphous structures.

[0062] The method for testing the alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 3:1. The system pressure is adjusted to 0.1 MPa and the temperature to 150 °C. The feedstock is introduced into the reactor for the dehydrogenation reaction according to a isopropanol-to-hydrogen molar ratio of 1:1. The liquid hourly space velocity (LHSV) of isopropanol is 0.8 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. The test results are shown in Table 1.

[0063] Example 4

[0064] (1) Weigh 6.5 g of lanthanum nitrate hexahydrate and 24.2 mL of tetraethyl orthosilicate (TEOS), dissolve them in 100 mL of ethanol solution, and stir to mix thoroughly. Then, add 20 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 40 min. Stir at 20 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0065] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 1 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 230 °C for hydrothermal reaction for 25 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 22.5%, La2O3 21.5%, SiO2 56.0%.

[0066] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was: reduction at 250℃ and 2.0 MPa in a H2 atmosphere for 2 hours. In the XRD pattern of the reduced catalyst, no additional diffraction peaks appeared besides the active metal. That is, both the SiO2 support and the promoter exist as amorphous structures.

[0067] The method for testing the alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 3:1. The system pressure is adjusted to 0.1 MPa and the temperature to 220℃. The raw material is introduced into the reactor for dehydrogenation reaction according to a cyclohexanol-to-hydrogen molar ratio of 1:1. The liquid hourly space velocity (LHSV) of cyclohexanol is 0.5 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. The test results are shown in Table 1.

[0068] Example 5

[0069] (1) Weigh 15.7 g of cerium nitrate hexahydrate and 24.2 mL of tetraethyl orthosilicate (TEOS), dissolve them in 100 mL of ethanol solution, and stir to mix evenly. Then, add 10 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 30 min. Stir at 20 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0070] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 4 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 17.0%, CeO2 40.5%, SiO2 42.5%.

[0071] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was: reduction at 180℃ and 3.0 MPa in a H2 atmosphere for 2 hours. In the XRD pattern of the reduced catalyst, no additional diffraction peaks appeared besides the active metal. That is, both the SiO2 support and the promoter exist as amorphous structures.

[0072] The test method for alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 5:1. The system pressure is adjusted to 0.1 MPa and the temperature to 120℃. The raw material is introduced into the reactor for dehydrogenation reaction according to a molar ratio of n-pentanol to hydrogen of 1:1. The liquid hourly space velocity (LHSV) of n-pentanol is 1 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. The test results are shown in Table 1.

[0073] Comparative Example 1

[0074] (1) Weigh 37.2 mL of tetraethyl orthosilicate (TEOS) and dissolve it in 100 mL of ethanol solution. Stir and mix thoroughly. Then, add 20 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 20 min. Stir at 20 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0075] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of a 2 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 40%, SiO2 60%.

[0076] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was as follows: reduction at 300℃ and 0.1MPa in an H2 atmosphere for 2 hours.

[0077] The method for testing the alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 5:1. The system pressure is adjusted to 0.1 MPa and the temperature to 260℃. The raw material is introduced into the reactor to carry out the dehydrogenation reaction according to a diethylene glycol-to-hydrogen molar ratio of 1:1. The liquid hourly space velocity (LHSV) of diethylene glycol is 1 h⁻¹. -1 The catalyst test results are shown in Table 1.

[0078] Comparative Example 2

[0079] 15.7 g of cerium nitrate hexahydrate, 20.5 g of copper nitrate trihydrate, and 24.2 mL of tetraethyl orthosilicate (TEOS) were weighed and dissolved in 100 mL of ethanol solution and stirred until homogeneous. Then, 25 wt% ammonia solution was added dropwise until the pH of the solution reached 10. The ammonia solution was added dropwise over 20 min. The mixture was stirred at 20 °C for 2 h to allow complete precipitation. The solid was then filtered, washed three times with deionized water, dried, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 17%, CeO2 40.5%, SiO2 42.5%.

[0080] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was as follows: reduction at 300℃ and 0.1 MPa in a H2 atmosphere for 2 hours. The XRD pattern of the reduced catalyst is shown below. Figure 1 In this example, both the active metal and the additives show diffraction peaks in the XRD pattern.

[0081] The method for testing the alcohol dehydrogenation reaction is as follows: 10 mL of catalyst is loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture is introduced with a nitrogen-to-hydrogen volume ratio of 5:1. The system pressure is adjusted to 0.1 MPa and the temperature to 260℃. The raw material is introduced into the reactor to carry out the dehydrogenation reaction according to a diethylene glycol-to-hydrogen molar ratio of 1:1. The liquid hourly space velocity (LHSV) of diethylene glycol is 1 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. Catalyst test results are shown in Table 1.

[0082] Comparative Example 3

[0083] (1) Weigh 15.7g of cerium nitrate hexahydrate and dissolve it in 100mL of ethanol solution and stir to mix evenly. Then add 20wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 20min. Stir at 20℃ for 2h to allow complete precipitation. After centrifugation, dry the solid at 100℃ for 12h and calcine at 250℃ for 2h.

[0084] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 2 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, dried at 100 °C for 12 h, and calcined at 350 °C for 4 h to obtain the catalyst. The catalyst composition was: CuO 15 wt%, CeO2 85 wt%.

[0085] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was the same as in Example 1.

[0086] The alcohol dehydrogenation reaction test method was the same as in Example 1. The test results are shown in Table 1.

[0087] Comparative Example 4

[0088] (1) Weigh 24.2 mL of tetraethyl orthosilicate (TEOS) and dissolve it in 100 mL of ethanol solution. Stir and mix thoroughly. Then, add 20 wt% ammonia solution dropwise until the pH of the solution is 10. The ammonia solution is added dropwise over 20 min. Stir at 20 °C for 2 h to allow complete precipitation. After centrifugation, dry the solid at 100 °C for 12 h and calcine at 250 °C for 2 h.

[0089] (2) The solid obtained in step (1) was ball-milled and dispersed in 100 mL of 2 mol / L copper ammonia solution to obtain a dispersion. The dispersion was transferred to a hydrothermal reactor and placed in an oven at 180 °C for hydrothermal reaction for 48 h. After cooling to room temperature (20 °C), the solid was filtered, washed three times with deionized water, and dried at 100 °C for 12 h.

[0090] (3) Weigh 15.7g of cerium nitrate hexahydrate and dissolve it in 50ml of deionized water. Add the solid obtained in step (2), stir and impregnate for 4h, then evaporate to dryness in an oil bath at 80℃ and calcine at 350℃ for 4h. The catalyst is obtained. The catalyst composition is: CuO 17%, CeO2 40.5%, SiO2 42.5%.

[0091] The application performance of the catalyst was tested. The catalyst was reduced before application. The reduction method was as follows: reduction at 300℃ and 0.1MPa for 2 hours in an H2 atmosphere. The alcohol dehydrogenation reaction test method was as follows: 10mL of catalyst was loaded into a fixed-bed reactor, and a nitrogen-hydrogen mixture was introduced, with a nitrogen to hydrogen volume ratio of 5:1. The system pressure was adjusted to 0.1MPa and the temperature to 260℃. The raw material was introduced into the reactor for the dehydrogenation reaction according to a diethylene glycol to hydrogen molar ratio of 1:1. The liquid hourly space velocity (LHSV) of diethylene glycol was 1 h⁻¹. -1 The reaction products were condensed to obtain a liquid product. The test results are shown in Table 1.

[0092] Table 1

[0093]

Claims

1. A copper-based catalyst for alcohol dehydrogenation reactions, comprising: (a) Active metal Cu; (b) Support SiO2; (c) Additives; said additives include one or more of ZrO2, CeO2, ZnO, and La2O3; The particle size of component (a) active metal Cu is 2–5 nm; The catalyst, based on the adsorbate, has a surface acidity of less than 0.01 mmol / g, preferably greater than or equal to 0.001 mmol / g and less than 0.01 mmol / g.

2. The catalyst according to claim 1, characterized in that, Both the carrier SiO2 (b) and the additive (c) are amorphous structures.

3. The catalyst according to claim 1, characterized in that, Based on the mass of the catalyst, the catalyst comprises: (a) 15 wt% to 30 wt% of active metal Cu, calculated as CuO; (b) 40 wt% to 58 wt% of support SiO2, based on SiO2; (c) 20 wt% to 45 wt% of additives, based on metal oxides.

4. A method for preparing the catalyst according to any one of claims 1 to 3, comprising: (1) Disperse the auxiliary agent source and silicon source in an organic alcohol, and then add ammonia water to carry out the reaction; Calcination of the solids after the reaction; (2) The calcination product from step (1) is dispersed in a copper ammonia solution and subjected to hydrothermal reaction and calcination to obtain the catalyst.

5. The method according to claim 4, characterized in that, In step (1), the auxiliary agent source is a salt containing the metal element in the auxiliary agent, preferably at least one of nitrate, acetate, sulfate, and chloride; And / or, the silicon source is at least one of tetraethyl orthosilicate (TEOS) and silica sol; And / or, the organic alcohol is at least one of methanol, ethanol, and isopropanol.

6. The method according to claim 4, characterized in that, In step (1), the volume ratio of organic alcohol to silicon source is 1:1 to 10:1; And / or, adjust the amount of ammonia added to make the pH of the reaction solution 10-12.

7. The method according to claim 4, characterized in that, In step (1), the reaction conditions are: reaction time 2-8 h, reaction temperature 10-60 °C; And / or, the calcination conditions are: calcination temperature of 200-500℃ and calcination time of 2-8h.

8. The method according to claim 4, characterized in that, In step (2), the molar concentration of copper in the copper ammonia solution is 0.5 to 5 mol / L; furthermore, the copper ammonia solution is a tetraamminecopper ion solution, preferably a tetraamminecopper nitrate solution.

9. The method according to claim 4, characterized in that, In step (2), the conditions for the hydrothermal reaction are: temperature 160-240℃, time 24-48h; And / or, the calcination conditions are: calcination temperature of 300-600℃ and calcination time of 2-8h.

10. The use of a catalyst according to any one of claims 1 to 3 or a catalyst prepared by the method according to any one of claims 4 to 9 in an alcohol dehydrogenation reaction.

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