Copper-based catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts and preparation thereof, and particularly relates to a copper-based catalyst and a preparation method and application thereof. The copper-based catalyst provided by the invention comprises a main catalyst, a cocatalyst and a carrier. The species Cu0 and Cu + of the main catalyst copper (Cu) are active centers of the copper-based catalyst, the reaction activity of the copper-based catalyst can be enhanced through the synergistic effect of the two, and the cocatalyst (M) and the main catalyst are tightly combined, so that the Cu0 and Cu + on the surface of the copper-based catalyst are stabilized in a specific proportion range. The copper-based catalyst provided by the invention has the advantages of excellent stability, high catalytic activity, high selectivity to methyl glycolate and high yield of methyl glycolate.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts and their preparation, and in particular relates to a copper-based catalyst and a preparation method and application thereof. Background Art

[0002] Polyglycolic acid (PGA), a key biodegradable polymer, is highly environmentally degradable, breaking down into carbon dioxide and water within 1-3 months in nature. Consequently, demand for PGA is enormous. Therefore, methyl glycolate, the raw material for its large-scale production, is crucial.

[0003] In recent years, the coal-based route has made great progress in dimethyl oxalate (DMO) hydrogenation technology. It is expected to achieve the synthesis of high-value-added biodegradable materials by regulating the hydrogenation reaction products. This process has high atomic utilization and is environmentally friendly, which is of great significance to promoting the high-end, diversified and low-carbon development of coal chemical products.

[0004] Currently, the catalysts used for the hydrogenation of dimethyl oxalate to produce methyl glycolate are primarily copper- and silver-based. However, existing copper-based catalysts, such as Cu / SiO2 or Cu-Ag / SiO2, suffer from the problem of sintering of the active copper metal, leading to catalyst deactivation and reduced catalyst stability. Summary of the invention

[0005] The purpose of the present invention is to provide a copper-based catalyst and a preparation method and application thereof. The copper-based catalyst provided by the present invention has excellent stability and high catalytic activity.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a copper-based catalyst, comprising a carrier and a main catalyst and a co-catalyst supported on the carrier; the main catalyst is copper, and the copper comprises Cu 0 and Cu + , the Cu 0 and Cu + The atomic ratio of is 0.4 to 0.6:1; the co-catalyst includes one or more of Co, Zn, Mn, Mg and Ni.

[0008] Preferably, the carrier is silicon oxide; the specific surface area of the carrier is not less than 100m 2 / g.

[0009] Preferably, the loading amount of the main catalyst is 6 to 20 wt %; the loading amount of the co-catalyst is 0.05 to 5 wt %.

[0010] Preferably, the particle size of the main catalyst is not greater than 8.0 nm; the particle size of the co-catalyst is 0.5 to 5.0 nm.

[0011] Preferably, the particle size of the copper-based catalyst is 0.8 to 6.0 nm.

[0012] The present invention also provides a preparation method of the copper-based catalyst described in the above solution, including the following steps:

[0013] A copper salt-M metal salt solution and a carrier precursor solution are subjected to vortex impact for high-entropy hydrolysis reaction, and then aging, adding alcohol to form a slurry, drying, and calcining are carried out in sequence to obtain the copper-based catalyst; the M metal salt in the copper salt-M metal salt solution includes one or more of cobalt salt, zinc salt, manganese salt, magnesium salt, and nickel salt.

[0014] Preferably, the temperature of the vortex impact is 60 to 90 °C; the flow rate of the copper salt-M metal salt solution is 2 to 20 mL / min; the flow rate of the carrier precursor solution is 2 to 30 mL / min.

[0015] Preferably, the high-entropy hydrolysis reaction is carried out under stirring conditions; the temperature of the high-entropy hydrolysis reaction is 60 to 90 °C, and the heat preservation time is 1 to 5 h.

[0016] The present invention also provides the application of the copper-based catalyst described in the above solution, the MoCu / SiO2 catalyst, or the copper-based catalyst obtained by the preparation method described in the above solution in the preparation of methyl glycolate; the MoCu / SiO2 catalyst includes a SiO2 carrier and a main catalyst and a promoter supported on the SiO2 carrier; the main catalyst is copper, and the copper includes Cu 0 and Cu + ; the atomic ratio of the Cu 0 and Cu + is 0.4 to 0.6:1; the promoter is Mo.

[0017] In the present invention, the method of the application includes the following steps: Dimethyl oxalate and the reduced copper-based catalyst are mixed, and hydrogen is introduced for hydrogenation reaction to obtain the methyl glycolate; the molar ratio of hydrogen to dimethyl oxalate is 10 to 300:1; the temperature of the hydrogenation reaction is 170 to 200 °C, and the pressure is 0.1 to 1.0 MPa.

[0018] The present invention provides a copper-based catalyst. The copper-based catalyst provided by the present invention includes a main catalyst, a promoter, and a carrier. The species Cu 0 and Cu + of the main catalyst copper (Cu) are the active centers of the copper-based catalyst, and the synergistic effect of the two can enhance the reaction activity of the copper-based catalyst. The promoter (M) and the main catalyst are closely combined, which helps to stabilize the Cu 0 and Cu +The copper-based catalyst provided by the present invention has excellent stability, high catalytic activity, high selectivity for methyl glycolate, high yield of methyl glycolate, and solves the problem of easy sintering of active metal copper.

[0019] The present invention also provides a method for preparing the copper-based catalyst described in the above scheme. This method utilizes impinging streams to mix a metal salt solution and a silicate solution in a high-entropy state to generate a metal silicate colloid. Fluid dynamics are then used to enhance the coagulation step, increasing the metal dispersion. Solvent evaporation is then used to increase the specific surface area of the catalyst, thereby enhancing the catalytic performance of the catalyst and producing a high-specific surface area, highly dispersed copper-based catalyst. The method for preparing the copper-based catalyst provided by the present invention features simple steps, readily available raw materials, and low production costs.

[0020] The present invention also provides the use of the copper-based catalyst described in the above embodiment or the copper-based catalyst obtained by the preparation method described in the above embodiment in the preparation of methyl glycolate. The copper-based catalyst provided by the present invention has high activity and good stability and is suitable for the preparation of methyl glycolate, particularly for the hydrogenation of dimethyl oxalate to prepare methyl glycolate. The required reaction conditions are mild (low temperature and low pressure), the H2 consumption is low, and the energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 XRD patterns of the copper-based catalysts prepared in Example 1 and Example 4;

[0023] Figure 2 This is a stability diagram of the copper-based catalyst prepared in Example 3;

[0024] Figure 3 This is a TEM image of the copper-based catalyst prepared in Example 4. DETAILED DESCRIPTION

[0025] The present invention provides a copper-based catalyst, comprising a carrier and a main catalyst and a co-catalyst supported on the carrier; the main catalyst is copper, and the copper comprises Cu 0 and Cu + , the Cu 0 and Cu + The atomic ratio of is 0.4 to 0.6:1; the co-catalyst includes one or more of Co, Zn, Mn, Mg and Ni.

[0026] The copper-based catalyst provided by the present invention includes a carrier; the carrier can be a silicon oxide; the silicon oxide can be SiO2; the specific surface area of the carrier can be not less than 100 m 2 / g, specifically it can be 100 m 2 / g, 200 m 2 / g, 300 m 2 / g, 500 m 2 / g, 1000 m 2 / g or 2000 m 2 / g.

[0027] The copper-based catalyst provided by the present invention includes a main catalyst; the loading amount (mass percentage of the copper-based catalyst) of the main catalyst can be 6-20 wt%, specifically it can be 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt% or 20 wt%.

[0028] In the present invention, the particle size of the main catalyst can be not more than 8.0 nm, specifically it can be 0.8 nm, 1.6 nm, 1.8 nm, 2.2 nm, 3.8 nm, 4.0 nm, 4.5 nm, 5.0 nm, 6.0 nm, 7.0 nm or 8.0 nm.

[0029] In the present invention, the ratio of Cu 0 and Cu + is 0.4-0.6:1, specifically it can be 0.4:1, 0.5:1 or 0.6:1; the average valence state of copper can be 0-1. The specific Cu 0 / Cu + ratio and non-Lewis acidity are beneficial to improving the selectivity of the copper-based catalyst to methyl glycolate.

[0030] The copper-based catalyst provided by the present invention includes a promoter; the loading amount (mass percentage of the copper-based catalyst) of the promoter can be 0.05-5 wt%, specifically it can be 0.05 wt%, 0.07 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt% or 5 wt%.

[0031] In the present invention, the particle size of the promoter can be 0.5-5.0 nm, specifically it can be 0.5 nm, 0.6 nm, 0.7 nm, 0.9 nm, 1.0 nm, 1.3 nm, 1.5 nm, 1.8 nm, 2.0 nm, 2.3 nm, 3.5 nm, 4.1 nm or 5.0 nm.

[0032] In the present invention, the particle size of the copper-based catalyst may be 0.8 to 6.0 nm, specifically 0.8 nm, 1.0 nm, 1.5 nm, 2.0 nm, 2.5 nm, 3.0 nm, 3.5 nm, 4.0 nm, 4.5 nm, 5.0 nm, 5.5 nm or 6.0 nm.

[0033] The present invention also provides a method for preparing the copper-based catalyst described in the above solution, comprising the following steps:

[0034] The copper salt-M metal salt solution and the carrier precursor solution are subjected to a vortex impact for a high-entropy hydrolysis reaction, and then aged, slurried with alcohol, dried and calcined in sequence to obtain the copper-based catalyst; the M metal salt in the copper salt-M metal salt solution includes one or more of cobalt salts, zinc salts, manganese salts, magnesium salts and nickel salts.

[0035] In the present invention, the copper salt-M metal salt solution and the carrier precursor solution are subjected to a vortex impact for a high-entropy hydrolysis reaction. In the present invention, the copper salt-M metal salt solution may include a copper salt, an M metal salt and a solvent; the copper salt-M metal salt solution may further include an inorganic acid; the inorganic acid may be nitric acid; the copper salt in the copper salt-M metal salt solution may include one or more of inorganic copper salts and organic copper salts; the inorganic copper salt may include one or more of copper nitrate, copper chloride and copper sulfate; the organic copper salt may be copper acetate.

[0036] In the present invention, the cobalt salt may be an inorganic cobalt salt; the inorganic cobalt salt may include one or more of cobalt nitrate, cobalt sulfate and cobalt chloride.

[0037] In the present invention, the zinc salt may be an inorganic zinc salt; the inorganic zinc salt may include one or more of zinc nitrate, zinc chloride and zinc sulfate.

[0038] In the present invention, the manganese salt may be an inorganic manganese salt; the inorganic manganese salt may include one or two of manganese nitrate and manganese sulfate.

[0039] In the present invention, the magnesium salt may be an inorganic magnesium salt; the inorganic magnesium salt may include one or more of magnesium nitrate and magnesium sulfate.

[0040] In the present invention, the nickel salt may include one or more of organic nickel salts and inorganic nickel salts; the organic nickel salt may be nickel acetate; the inorganic nickel salt may include one or more of nickel nitrate, nickel sulfate and nickel chloride.

[0041] In the present invention, the solvent in the copper salt-M metal salt solution may be water; the water may be deionized water.

[0042] In the present invention, the total concentration of the copper salt and the M metal salt in the copper salt-M metal salt solution can be 0.03 to 3.2 mol / L, specifically, it can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.7 mol / L, 2 mol / L, 2.5 mol / L or 3.2 mol / L.

[0043] In the present invention, the molar ratio of the copper salt to the M metal salt in the copper salt-M metal salt solution can be 10 to 15:1 to 3, specifically, it can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 10:2, 11:2, 12:2, 13:2, 14:2, 15:2, 10:3, 11:3, 12:3, 13:3, 14:3 or 15:3.

[0044] In the present invention, the concentration of the inorganic acid in the copper salt-M metal salt solution can be 0.2 to 5.0 wt%, specifically, it can be 0.2 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt% or 5.0 wt%.

[0045] In the present invention, the carrier precursor in the carrier precursor solution can be a silicate; the silicate can be a metal silicate; the metal silicate can be sodium silicate.

[0046] In the present invention, the solute in the carrier precursor solution can be water; the water can be deionized water.

[0047] In the present invention, the concentration of the carrier precursor in the carrier precursor solution can be 0.5 to 18 mol / L, specifically, it can be 0.5 mol / L, 1 mol / L, 2 mol / L, 5 mol / L, 7 mol / L, 10 mol / L, 12 mol / L, 15 mol / L or 18 mol / L.

[0048] In the present invention, the volume ratio of the copper salt-M metal salt solution to the carrier precursor solution can be 1 to 4:1 to 2, specifically, it can be 1:1, 2:1, 3:1, 4:1, 1:1.5, 2:1.5, 3:1.5, 4:1.5, 1:2 or 3:2.

[0049] In the present invention, the vortex impact can be: under stirring conditions, water is added to the vortex reactor, and the copper salt-M metal salt solution and the carrier precursor solution are respectively pumped into the vortex reactor by a liquid-phase pump, generating high-frequency vortices and impact flows in the vortex reactor.

[0050] In the present invention, the temperature of the eddy current impact may be 60-90°C, specifically 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C.

[0051] In the present invention, the stirring speed may be 50 to 1000 rpm, specifically 100 rpm, 300 rpm, 500 rpm, 700 rpm or 900 rpm.

[0052] In the present invention, the water used for adding water can be deionized water; the volume ratio of the water to the carrier precursor solution can be 1:2 to 100, specifically 1:2, 1:5, 1:7, 1:10, 1:12, 1:15, 1:17, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, or 1:100. The present invention controls the hydrolysis rate of the carrier precursor silicate and the degree of polymerization of the carrier SiO2 by adding water, thereby promoting the dispersion of the active metal.

[0053] In the present invention, the flow rate of the copper salt-M metal salt solution can be 2 to 20 mL / min, specifically 5 mL / min, 10 mL / min, 15 mL / min or 18 mL / min; the flow rate of the carrier precursor solution can be 2 to 30 mL / min, specifically 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min or 28 mL / min.

[0054] In the present invention, the high entropy hydrolysis reaction is carried out under stirring conditions; the temperature of the high entropy hydrolysis reaction can be 60 to 90° C., specifically 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., or 90° C., and the holding time can be 1 to 5 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours. The present invention obtains a slurry through eddy current impact and high entropy hydrolysis reaction.

[0055] In the present invention, the high entropy hydrolysis reaction may include reacting while adding materials and continuing the reaction after stopping the addition of materials; the time for continuing the reaction after stopping the addition of materials may be 20 minutes.

[0056] After the high-entropy hydrolysis reaction, the present invention sequentially performs aging, alcohol addition to form a slurry, drying, and calcination to obtain the copper-based catalyst. In the present invention, the aging can be performed under static conditions; the aging temperature can be 60 to 100°C, specifically 60°C, 70°C, 80°C, 90°C, or 100°C, and the holding time can be 12 to 48 hours, specifically 12 hours, 18 hours, 24 hours, 30 hours, 36 hours, 42 hours, or 48 hours. The present invention obtains a colloid through aging.

[0057] In the present invention, the aging step may further include washing the colloid obtained by aging; the washing reagents may be water and alcohol; the alcohol may be ethanol; the number of washing times may be more than 7 times, specifically 7 times, 8 times, 9 times or 10 times.

[0058] In the present invention, the alcohol for adding alcohol may be a C1-C8 alcohol; the C1-C8 alcohol may include one or more of n-butanol, isobutanol, isopropanol, n-pentanol and isopentanol.

[0059] In the present invention, the volume ratio of the alcohol for adding alcohol to the colloid can be 1-3:1-2, specifically 1:1, 2:1, 3:1, 1:1.5, 2:1.5, 3:1.5, 1:2 or 3:2.

[0060] In the present invention, the slurrying may be: adding alcohol to the colloid and stirring; the stirring time may be 1 to 4 hours, specifically 1 hour, 2 hours, 3 hours or 4 hours.

[0061] In the present invention, the drying temperature may be 90° C., until solid is obtained by evaporation.

[0062] In the present invention, the calcination can be carried out in air or protective gas; the protective gas can be an inert gas or nitrogen; the inert gas can be argon; the calcination temperature can be 350-450°C, specifically 350°C, 375°C, 400°C, 430°C or 450°C, and the holding time can be 2-6h, specifically 2h, 3h, 4h, 5h or 6h.

[0063] The present invention also provides the use of the copper-based catalyst, MoCu / SiO2 catalyst or the copper-based catalyst obtained by the preparation method of the above scheme in the preparation of methyl glycolate; the MoCu / SiO2 catalyst comprises a SiO2 carrier and a main catalyst and a co-catalyst supported on the SiO2 carrier; the main catalyst is copper, and the copper comprises Cu 0 and Cu + , the Cu 0 and Cu + The atomic ratio of is 0.4-0.6:1; and the co-catalyst is Mo.

[0064] In the present invention, the application method may include the following steps: mixing dimethyl oxalate and a reduced copper-based catalyst, introducing hydrogen gas to carry out a hydrogenation reaction, and obtaining the methyl glycolate.

[0065] In the present invention, the reduction gas may be hydrogen.

[0066] In the present invention, the mass space velocity of dimethyl oxalate can be 0.1 to 10.0 g / g·cat / h, specifically 0.2g / g·cat / h, 0.5g / g·cat / h, 1.0g / g·cat / h, 2.0g / g·cat / h, 3.0g / g·cat / h, 5.0g / g·cat / h, 7.5g / g·cat / h or 9.5g / g· cat / h.

[0067] In the present invention, the molar ratio of hydrogen to dimethyl oxalate may be 10 to 300:1, specifically 10:1, 30:1, 50:1, 65:1, 80:1, 100:1, 150:1, 200:1, 250:1 or 300:1.

[0068] In the present invention, the introduction of hydrogen into the copper-based catalyst and dimethyl oxalate may be performed by loading the copper-based catalyst into an isothermal zone in a fixed-bed reactor, with the upper and lower portions both filled and supported with quartz sand, then introducing hydrogen into the fixed-bed reactor, and after the catalyst is reduced by hydrogen, adjusting the temperature and pressure to a hydrogenation reaction temperature and pressure, and injecting the dimethyl oxalate solution into the fixed-bed reactor by a constant flow pump for hydrogenation.

[0069] In the present invention, the hourly space velocity of dimethyl oxalate can be 0.2 to 3.0 h -1 , specifically 0.2h -1 , 0.7h -1 , 1h -1 , 1.5h -1 , 2h -1 , 2.4h -1 , 2.7h -1 or 3 hours -1 .

[0070] In the present invention, the temperature of the hydrogenation reaction may be 170-200°C, specifically 170°C, 180°C, 190°C or 200°C, and the pressure may be 0.1-1.0 MPa, specifically 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa or 1.0 MPa.

[0071] In the present invention, the dimethyl oxalate solution can be a mixed solution of dimethyl oxalate and methanol; the concentration of dimethyl oxalate in the dimethyl oxalate solution can be 4-12.5%, specifically 4%, 6%, 8%, 10%, 12% or 12.5%. When the concentration of the dimethyl oxalate solution is high, the temperature and pressure of the raw material tank can be appropriately increased to ensure that the dimethyl oxalate is completely dissolved in the methanol and the reactants are in a liquid state.

[0072] In order to further illustrate the present invention, the scheme of the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0073] Example 1

[0074] 15 mmol of copper nitrate and 3 mmol of zinc nitrate were dissolved in 200 mL of deionized water, and then 3 mL of 63 wt % nitric acid was added to the resulting solution to obtain solution A.

[0075] 28.4 g of sodium silicate was dissolved in 150 mL of deionized water to obtain solution B.

[0076] 30 mL of deionized water was added to the vortex reactor and heated to 70° C., and then the solution A and solution B were respectively pumped into the vortex reactor using liquid phase pumps. The flow rate of solution A was 10 mL / min, and the flow rate of solution B was 10 mL / min. High-frequency vortexes and impact flows were generated in the vortex reactor. After the addition was completed, the reaction was continued for 2 h to obtain slurry C.

[0077] The slurry C was aged at 80° C. for 24 hours to obtain colloid D.

[0078] The colloid D was washed 7 times with a water / ethanol solution, and 100 mL of n-butanol was added to the washed colloid D and stirred for 2 h to obtain slurry E.

[0079] The slurry E was heated to 90°C and evaporated to dryness to obtain solid F.

[0080] The solid F was dried and then calcined in air at 350° C. for 4 h to obtain a CuZn / SiO 2 catalyst.

[0081] Example 2

[0082] 15 mmol of copper chloride and 2 mmol of zinc nitrate were dissolved in 200 mL of deionized water, and then 3 mL of 63 wt% nitric acid was added to the resulting solution to obtain solution A.

[0083] 28.4 g of sodium silicate was dissolved in 150 mL of deionized water to obtain solution B.

[0084] 30 mL of deionized water was added to the vortex reactor and heated to 70° C., and then the solution A and solution B were respectively pumped into the vortex reactor using liquid phase pumps. The flow rate of solution A was 12 mL / min, and the flow rate of solution B was 15 mL / min. High-frequency vortexes and impact flows were generated in the vortex reactor. After the addition was completed, the reaction was continued for 3 h to obtain slurry C.

[0085] The slurry C was aged at 90° C. for 20 h to obtain colloid D.

[0086] The colloid D was washed 8 times with a water / ethanol solution, and 100 mL of n-pentanol was added to the washed colloid D, and the mixture was stirred for 3 h to obtain slurry E.

[0087] The slurry E was heated to 90°C and evaporated to dryness to obtain solid F.

[0088] The solid F was dried and then calcined in argon at 400° C. for 6 h to obtain a CuZn / SiO 2 catalyst.

[0089] Example 3

[0090] 10 mmol of copper acetate and 1 mmol of manganese nitrate were dissolved in 200 mL of deionized water, and then 3 mL of 63 wt % nitric acid was added to the resulting solution to obtain solution A.

[0091] 28.4 g of sodium silicate was dissolved in 150 mL of deionized water to obtain solution B.

[0092] 30 mL of deionized water was added to the vortex reactor and heated to 80° C., and then the solution A and solution B were respectively pumped into the vortex reactor using liquid phase pumps. The flow rate of solution A was 10 mL / min, and the flow rate of solution B was 10 mL / min. High-frequency vortexes and impact flows were generated in the vortex reactor. After the addition was completed, the reaction was continued for 3 h to obtain slurry C.

[0093] The slurry C was aged at 90° C. for 24 hours to obtain colloid D.

[0094] The colloid D was washed 8 times with a water / ethanol solution, and 100 mL of n-butanol was added to the washed colloid D and stirred for 3 h to obtain slurry E.

[0095] The slurry E was heated to 90°C and evaporated to dryness to obtain solid F.

[0096] The solid F was dried and then calcined at 450° C. for 5 h in nitrogen to obtain a CuMn / SiO 2 catalyst.

[0097] Example 4

[0098] 10 mmol of copper acetate and 1 mmol of nickel acetate were dissolved in 200 mL of deionized water, and then 3 mL of 63 wt % nitric acid was added to the resulting solution to obtain solution A.

[0099] 28.4 g of sodium silicate was dissolved in 150 mL of deionized water to obtain solution B.

[0100] Add 30 mL of deionized water to the eddy current reactor and heat it to 90 °C. Then, pump solution A and solution B into the eddy current reactor respectively using a liquid-phase pump. The flow rate of solution A is 10 mL / min, and the flow rate of solution B is 10 mL / min. High-frequency vortices and impinging streams are generated in the eddy current reactor. After the feeding is completed, continue the reaction for 2 h to obtain slurry C.

[0101] Let the slurry C stand and age at 80 °C for 40 h to obtain colloid D.

[0102] Wash the colloid D 9 times with a water / ethanol solution. Add 100 mL of n-butanol to the washed colloid D and stir for 4 h to obtain slurry E.

[0103] Heat the slurry E to 90 °C and evaporate to dryness to obtain solid F.

[0104] Dry the solid F and then calcine it in nitrogen at 450 °C for 5 h to obtain the CuNi / SiO₂ catalyst.

[0105] Example 5

[0106] Dissolve 10 mmol of copper nitrate and 2.4 mmol of nickel acetate in 200 mL of deionized water. Then, add 3 mL of nitric acid with a concentration of 63 wt% to the resulting solution to obtain solution A.

[0107] Dissolve 28.4 g of sodium silicate in 150 mL of deionized water to obtain solution B.

[0108] Add 30 mL of deionized water to the eddy current reactor and heat it to 90 °C. Then, pump solution A and solution B into the eddy current reactor respectively using a liquid-phase pump. The flow rate of solution A is 15 mL / min, and the flow rate of solution B is 15 mL / min. High-frequency vortices and impinging streams are generated in the eddy current reactor. After the feeding is completed, continue the reaction for 3 h to obtain slurry C.

[0109] Let the slurry C stand and age at 80 °C for 40 h to obtain colloid D.

[0110] Wash the colloid D 9 times with a water / ethanol solution. Add 100 mL of isopentanol to the washed colloid D and stir for 4 h to obtain slurry E.

[0111] Heat the slurry E to 90 °C and evaporate to dryness to obtain solid F.

[0112] Dry the solid F and then calcine it in nitrogen at 450 °C for 5 h to obtain the CuNi / SiO₂ catalyst.

[0113] Example 6

[0114] Dissolve 10 mmol of copper nitrate and 2.0 mmol of cobalt nitrate in 200 mL of deionized water, and then add 3 mL of nitric acid with a concentration of 63 wt% to the resulting solution to obtain solution A.

[0115] Dissolve 28.4 g of sodium silicate in 150 mL of deionized water to obtain solution B.

[0116] Add 30 mL of deionized water to the vortex reactor and heat it to 90 °C. Then, pump solution A and solution B into the vortex reactor using a liquid-phase pump respectively. The flow rate of solution A is 10 mL / min, and the flow rate of solution B is 10 mL / min. High-frequency vortices and impinging streams are generated in the vortex reactor. After the feeding is completed, continue the reaction for 2 h to obtain slurry C.

[0117] Let the slurry C stand and age at 80 °C for 40 h to obtain colloid D.

[0118] Wash the colloid D 9 times with a water / ethanol solution. Add 100 mL of isopentanol to the washed colloid D and stir for 4 h to obtain slurry E.

[0119] Heat the slurry E to 90 °C and evaporate it to dryness to obtain solid F.

[0120] Dry the solid F and calcine it in nitrogen at 450 °C for 5 h to obtain the CuCo / SiO2 catalyst.

[0121] Example 7

[0122] Dissolve 10 mmol of copper nitrate and 2.2 mmol of magnesium nitrate in 200 mL of deionized water, and then add 3 mL of nitric acid with a concentration of 63 wt% to the resulting solution to obtain solution A.

[0123] Dissolve 28.4 g of sodium silicate in 150 mL of deionized water to obtain solution B.

[0124] Add 30 mL of deionized water to the vortex reactor and heat it to 90 °C. Then, pump solution A and solution B into the vortex reactor using a liquid-phase pump respectively. The flow rate of solution A is 10 mL / min, and the flow rate of solution B is 10 mL / min. High-frequency vortices and impinging streams are generated in the vortex reactor. After the feeding is completed, continue the reaction for 2 h to obtain slurry C.

[0125] Let the slurry C stand and age at 80 °C for 40 h to obtain colloid D.

[0126] Wash the colloid D 9 times with a water / ethanol solution. Add 100 mL of isopentanol to the washed colloid D and stir for 4 h to obtain slurry E.

[0127] Heat the slurry E to 90 °C and evaporate it to dryness to obtain solid F.

[0128] The solid F was dried and then calcined at 450° C. for 5 h in nitrogen to obtain a CuMg / SiO 2 catalyst.

[0129] Comparative Example 1

[0130] 15 mmol of copper nitrate was dissolved in 200 mL of deionized water, and then 3 mL of 63 wt % nitric acid was added to the resulting solution to obtain solution A.

[0131] The solution A was added to 14.0 g of powdered SiO2, and the mixture was impregnated at equal volumes for 2 h. The resulting solid was dried in an oven at 90° C. and then calcined in air at 350° C. for 4 h to obtain an IM-Cu / SiO2 catalyst.

[0132] Comparative Example 2

[0133] 15 mmol of copper nitrate and 3 mmol of zinc nitrate were dissolved in 200 mL of deionized water, and then 3 mL of 63 wt % nitric acid was added to the resulting solution to obtain solution A.

[0134] The solution A was added to 14.0 g of powdered SiO2, and the mixture was impregnated at equal volumes for 2 h. The resulting solid was dried in an oven at 90° C. and then calcined in air at 350° C. for 4 h to obtain an IM-CuZn / SiO2 catalyst.

[0135] Comparative Example 3

[0136] 10 mmol of copper acetate was dissolved in 200 mL of deionized water, and then 3 mL of 63 wt % nitric acid was added to the resulting solution to obtain solution A.

[0137] 28.4 g of sodium silicate was dissolved in 150 mL of deionized water to obtain solution B.

[0138] 50 mL of deionized water was added to a three-necked flask and heated to 80° C., and then the solution A and solution B were added in parallel under strong stirring. After the addition, stirring was continued for 2 h to obtain slurry C.

[0139] The slurry C was aged at 90° C. for 24 hours to obtain colloid D.

[0140] The colloid D was washed 8 times with a water / ethanol solution, and 100 mL of n-butanol was added to the washed colloid D and stirred for 3 h to obtain slurry E.

[0141] The slurry E was heated to 90°C and evaporated to dryness to obtain solid F.

[0142] The solid F was dried and then calcined at 450° C. for 5 h in nitrogen to obtain a Cu / SiO 2 catalyst.

[0143] Comparative Example 4

[0144] Dissolve 10 mmol of copper acetate and 1 mmol of nickel acetate in 200 mL of deionized water, and then add 3 mL of nitric acid with a concentration of 63 wt% to the resulting solution to obtain Solution A.

[0145] Dissolve 28.4 g of sodium silicate in 150 mL of deionized water to obtain Solution B.

[0146] Add 50 mL of deionized water to a three-necked flask and heat it to 90 °C, then add the Solution A and Solution B in a co-current manner under strong stirring. After the addition, continue stirring for 2 h to obtain Slurry C.

[0147] Let the Slurry C stand and age at 80 °C for 40 h to obtain Colloid D.

[0148] Wash the Colloid D 9 times with a water / ethanol solution, add 100 mL of n-butanol to the washed Colloid D, and stir for 4 h to obtain Slurry E.

[0149] Heat the Slurry E to 90 °C and evaporate to dryness to obtain Solid F.

[0150] Dry the Solid F and then calcine it in nitrogen at 650 °C for 5 h to obtain the H-CuNi / SiO2 catalyst.

[0151] Comparative Example 5

[0152] Dissolve 10 mmol of copper acetate and 1 mmol of nickel acetate in 200 mL of deionized water, and then add 3 mL of nitric acid with a concentration of 63 wt% to the resulting solution to obtain Solution A.

[0153] Dissolve 28.4 g of sodium silicate in 150 mL of deionized water to obtain Solution B.

[0154] Add 50 mL of deionized water to a three-necked flask and heat it to 90 °C, then add the Solution A and Solution B in a co-current manner under strong stirring. After the addition, continue stirring for 2 h to obtain Slurry C.

[0155] Let the Slurry C stand and age at 80 °C for 40 h to obtain Colloid D.

[0156] Wash the Colloid D 9 times with a water / ethanol solution, centrifuge it, dry it in an oven at 90 °C, and calcine it in a muffle furnace at 400 °C for 5 h to obtain the M-CuNi / SiO2 catalyst.

[0157] Test Example 1

[0158] The hydrogenation reaction of dimethyl oxalate was tested on the catalysts prepared in Examples 1-7 and Comparative Examples 1-5. The specific test steps were the same, and the mass space velocity of dimethyl oxalate, the molar ratio of hydrogen to dimethyl oxalate, the reaction pressure, and the reaction temperature were partially adjusted. The test results of the reaction performance are shown in Table 1.

[0159] Table 1 Test Results of the Catalysts in Examples 1-7 and Comparative Examples 1-5

[0160]

[0161]

[0162] It can be seen from Table 1 that the catalysts prepared in Examples 1-7 of the present invention have better catalytic effects on the hydrogenation reaction of dimethyl oxalate, with high raw material conversion rates, good selectivities for target products, and improved overall utilization rates of raw materials.

[0163] Test Example 2

[0164] The XRD patterns of the catalysts prepared in Example 1 and Example 4 were analyzed by X-ray diffraction, and the results are as Figure 1 shown. According to Figure 1 it can be seen that the catalyst only shows relatively diffuse diffraction peaks of SiO2, and no obvious diffraction peaks of Cu are seen, indicating that Cu is highly dispersed on the catalyst support and the crystal grains are very small.

[0165] Test Example 3

[0166] The stability test of the catalyst prepared in Example 3 was carried out under the test conditions of: 170 °C, 0.15 MPa, WLHSV = 0.6 h -1 , and the hydrogen-to-ester ratio = 60. The results are as Figure 2 shown (wherein, EG is ethylene glycol, MG is methyl glycolate, and DMO is dimethyl oxalate).

[0167] According to Figure 2 it can be seen that the DMO conversion rate of the catalyst basically remains at 90% during the stable test process of about 5000 h, and the selectivity of methyl glycolate (MG) is stable at about 85%, indicating that the catalyst has excellent stability and mild reaction conditions.

[0168] Test Example 4

[0169] The TEM test of the catalyst prepared in Example 4 was carried out by using a transmission electron microscope, and the results are as Figure 3 shown. According to Figure 3 it can be seen that no obvious agglomeration of Cu and the promoter metal is seen, and they are evenly dispersed on the carrier SiO2, indicating that the active metal exhibits excellent dispersion.

[0170] As can be seen from the above examples, the copper-based catalyst provided by the present invention has excellent stability, high catalytic activity, high selectivity for methyl glycolate, high yield of methyl glycolate, mild reaction conditions, low hydrogen consumption, and broad application prospects.

[0171] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A copper-based catalyst, characterized in that, It includes a carrier and a main catalyst and a promoter supported on the carrier; the main catalyst is copper, and the copper includes Cu 0 and Cu + , and the atomic ratio of the Cu 0 and Cu + is 0.4 to 0.6:1; the promoter includes one or more of Co, Zn, Mn, Mg, and Ni.

2. The copper-based catalyst according to claim 1, characterized in that, The carrier is silicon oxide; the specific surface area of the carrier is not less than 100 m 2 / g.

3. The copper-based catalyst according to claim 1, wherein The loading amount of the main catalyst is 6-20 wt%; the loading amount of the cocatalyst is 0.05-5 wt%.

4. The copper-based catalyst according to claim 1 or 3, characterized in that, The particle size of the main catalyst is not more than 8.0 nm; the particle size of the cocatalyst is 0.5-5.0 nm.

5. The copper-based catalyst according to claim 1 or 2, characterized in that, The particle size of the copper-based catalyst is 0.8-6.0 nm.

6. The preparation method of the copper-based catalyst according to any one of claims 1 to 5, characterized in that, It includes the following steps: The copper salt-M metal salt solution and the carrier precursor solution are subjected to vortex impact for high-entropy hydrolysis reaction, followed by aging, adding alcohol to form a slurry, drying and calcining in sequence to obtain the copper-based catalyst; the M metal salt in the copper salt-M metal salt solution includes one or more of cobalt salt, zinc salt, manganese salt, magnesium salt and nickel salt.

7. The preparation method according to claim 6, characterized in that, The temperature of the vortex impact is 60-90 °C; the flow rate of the copper salt-M metal salt solution is 2-20 mL / min; the flow rate of the carrier precursor solution is 2-30 mL / min.

8. The preparation method according to claim 6 or 7, characterized in that, The high-entropy hydrolysis reaction is carried out under stirring conditions; the temperature of the high-entropy hydrolysis reaction is 60-90 °C, and the heat preservation time is 1-5 h.

9. Use of the copper-based catalyst according to any one of claims 1 to 5, the MoCu / SiO2 catalyst, or the copper-based catalyst obtained by the preparation method according to any one of claims 6 to 8 in the preparation of methyl glycolate; the MoCu / SiO2 catalyst comprises a SiO2 support and a main catalyst and a promoter supported on the SiO2 support; the main catalyst is copper, and the copper comprises Cu 0 and Cu + , and the atomic ratio of the Cu 0 and Cu + is 0.4 to 0.6:1; the promoter is Mo.

10. The application according to claim 9, wherein The application method includes the following steps: dimethyl oxalate and the reduced copper-based catalyst are mixed, and hydrogen is introduced for hydrogenation reaction to obtain methyl glycolate; the molar ratio of hydrogen to dimethyl oxalate is 10-300:1; the temperature of the hydrogenation reaction is 170-200 °C, and the pressure is 0.1-1.0 MPa.

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