CN109433206B

CN109433206B - Preparation method of mesoporous silica supported copper catalyst with central radial pore passage

Info

Publication number: CN109433206B
Application number: CN201811430899.5A
Authority: CN
Inventors: 王志光; 王建青; 王炳春; 李进
Original assignee: China Catalyst New Material Co ltd
Current assignee: China Catalyst New Material Co ltd
Priority date: 2018-11-28
Filing date: 2018-11-28
Publication date: 2021-07-23
Anticipated expiration: 2038-11-28
Also published as: CN109433206A

Abstract

The invention discloses a preparation method of a mesoporous silica supported copper catalyst with a central radial pore passage, which comprises the steps of mixing diethyl ether, ethanol, ammonia water and water, adding a long-chain structure guiding agent and an organic silicon compound, reacting, filtering, washing, drying and roasting to obtain a silica nanosphere; adjusting the pH value of the soluble copper salt solution to 1-2 by using an acid solution, adding the silicon oxide nanospheres, stirring, adding an ammonium carbonate solution to adjust the pH value to 6-8, and filtering, washing, drying and roasting the solid product to obtain the catalyst product. The copper content in the prepared catalyst is 10-45% of the total weight of the catalyst, and the monovalent copper content is 20-60 mol% of the total active copper mol number; specific surface area of catalyst>500m²G, pore volume>1.0ml/g, and the average mesoporous size is 2.8-10 nm. The catalyst is used for the reaction of synthesizing glycol by hydrogenating dimethyl oxalate, and the conversion rate of dimethyl oxalate>99% ethylene glycol selectivity>96％。

Description

Preparation method of mesoporous silica supported copper catalyst with central radial pore passage

Technical Field

The invention relates to a preparation method of a hydrogenation catalyst, in particular to a preparation method of a silicon oxide loaded copper catalyst for dimethyl oxalate hydrogenation.

Background

Dimethyl oxalate (DMO) hydrogenation is the most critical step in the process of synthesizing ethylene glycol by CO coupling method. Meanwhile, dimethyl oxalate hydrogenation can be used for producing ethylene glycol, Methyl Glycolate (MG) and ethanol, which are important components of the coal chemical industry chain. U.S. UCC began to apply for two patents on the hydrogenation of dimethyl oxalate in 1985, and U.S. Pat. No. 4,467,7234 discloses a Cu-Si catalyst prepared by using copper carbonate and ammonium carbonate as raw materials; US4628128 describes a Cu-Si catalyst prepared by an impregnation process. US 4112242245 mainly adopts a coprecipitation method to prepare Cu-Zn-Cr and Cu-Cr system catalysts, and introduces auxiliaries such as Ca, Cr and the like. The dimethyl oxalate hydrogenation catalyst mainly comprises a Cu-Si system and a Cu-Cr system, and although the Cu-Cr catalyst has better activity, Cr is extremely toxic and has large pollution, so that the catalyst is basically eliminated at present. Therefore, the Cu-Si system catalyst has good development prospect. However, various auxiliaries are introduced into the Cu-Si system, and the action mechanism and the action effect of the auxiliaries are unclear. The preparation route of the catalyst is still mainly based on the traditional coprecipitation method, impregnation method, sol-gel method and the like.

The use of SiO in recent years₂Research and application of a copper-based catalyst for preparing ethylene glycol by hydrogenating oxalate and prepared by a carrier become hot spots in the research field and make certain progress. Japanese UBE corporation U.S. Pat. No. 4,85890 produced Cu/SiO by solvent evaporation₂The catalyst is used for ensuring that the highest ethylene glycol selectivity reaches 99.5 percent when the oxalic ester conversion rate is 100 percent in the diethyl oxalate hydrogenation reaction; because copper metal has the defects of low activity, easy sintering at high temperature, poor strength and the like, pure Cu/SiO₂The stability of the catalyst is poor, and the service life of the catalyst cannot meet the requirement of industrial application. Patent CN101455976A uses hexagonal mesoporous molecular sieve (HMS) as carrier to prepare an oxalate hydrogenation catalyst loaded with copper and other auxiliary metals, wherein Cu-Mn/SiO takes manganese as auxiliary₂The catalyst is used in the hydrogenation reaction of dimethyl oxalate, the reaction pressure is 3.0MPa, the reaction temperature is 200 ℃, and H is₂When the conversion rate of oxalate can reach 100%, the selectivity of glycol is 91%, and when other conditions are not changed, H is added when the conversion rate of oxalate is 50(mo1/mo1)₂The ethylene glycol selectivity was 95% when the DMO rose to 180 (mol/mol). However, in practical applications, the hydrogen ester ratio is too high to meet the performance requirements of the recycle compressor, which can greatly increase the production cost.

Cu-Cr catalyst and Cu/SiO prepared by coprecipitation method and sol-gel method used in Fujian material structure research institute of Chinese academy of sciences₂The catalyst is used at the reaction pressure of 2.5-3 MPa, the reaction temperature of 208-230 ℃ and the space velocity of 2500-6000 h^-1The molar ratio of hydrogen to ester is 20-60And (5) stable operation 1134 h. The best results are a conversion of 99.8% for dimethyl oxalate and an average selectivity for ethylene glycol of 95.3%. The Tianjin university adopts Cu-Zn/SiO₂The catalyst has dimethyl oxalate converting rate over 90% and glycol selectivity over 90% at 2.0MPa and 220 deg.c. The university of eastern China science and technology adopts Cu/SiO₂The catalyst is prepared by the following best conditions: the reaction temperature is 190-200 ℃, the reaction pressure is 2.5MPa, the molar ratio of hydrogen to ester is 60, the conversion rate of dimethyl oxalate reaches about 95%, and the selectivity of ethylene glycol reaches about 90%. The catalyst has high reaction temperature and pressure and low ethylene glycol selectivity, so that the heat and power consumption is high, the byproducts are increased, and in addition, the copper catalyst is easy to generate grain agglomeration and inactivation, so that the service life of the catalyst is difficult to meet the industrial requirement. Therefore, the oxalate hydrogenation catalyst suitable for industrial application firstly needs to have the stability capable of meeting the requirements of industrial application, and secondly has high oxalate conversion rate and high glycol selectivity on the basis of high stability.

Recently, the mesoporous silica nanospheres with the radial center have excellent pore characteristics such as short diffusion distance, monodispersity, high pore volume and high accessible internal surface area; the synthesis method is different from the traditional soft/hard template method, and an unstable interface is formed through complex kinetic assembly between a silicon source and a surfactant. The special structure is beneficial to the diffusion of substances and the arrangement of active sites, and can be particularly applied to metal-loaded catalyst carriers, thereby improving the dispersion degree and the reaction center activity of metal active components, increasing the stability of industrial application and prolonging the service life.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art and provides a mesoporous silica supported copper catalyst with a central radial pore passage, and a preparation method and application thereof. The method is green and clean, and the prepared catalyst has good low-temperature activity, high selectivity and good stability; the method is mainly used for synthesizing the ethylene glycol by hydrogenating the dimethyl oxalate. According to the invention, the silicon oxide nanospheres with the pore canals in the central radial shape are used as the carrier, the size and the dispersity of copper species in the final catalyst are regulated and controlled, and the synergistic effect of monovalent copper and zero-valent copper is improved to improve the catalytic performance of the catalyst. In the invention, the mesoporous silica nano particle with the central radial pore canal has a central radial pore canal structure, and the pore canal size is gradually increased from the inside of the particle to the surface of the particle, so that the mesoporous silica nano particle is a porous material with a novel structure; compared with the traditional mesoporous silica particles with two-dimensional hexagonal ordered pore channel structures, the mesoporous silica particles have a three-dimensional open central radial skeleton structure, so that the mesoporous silica particles have unique structural advantages of high pore permeability and high accessibility of the inner surfaces of the particles, and are favorable for conveying substances (molecules or nanoparticles) along central radial pore channels, and the substances (molecules or nanoparticles) are loaded in the mesoporous silica or react with active sites in the mesoporous silica.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention firstly provides a preparation method of a mesoporous silica supported copper catalyst with a central radial pore passage, which comprises the following steps:

(1) mixing diethyl ether, ethanol, ammonia water and water to form a uniform solution, adding a long-chain structure guiding agent into the uniform solution, stirring at the room temperature at 500-2000 rpm for 0.5-2 hours to form a mixture, quickly dripping an organic silicon compound into the mixture, stirring at the 500-2000 rpm for 0.5-2 hours, heating to 40-60 ℃, reacting for 4-24 hours, and forming a white precipitate; in the white precipitate obtained (organosilicon compound in the form of SiO)₂Calculated), the molar ratio of each material is as follows: SiO2₂: diethyl ether: ethanol: long chain structure directing agent: NH (NH)₃：H₂O＝1：(15～45)：(15～40)：(0.08～0.2)：(0.5～1.5)：(250～350)；

(2) Filtering and washing the white precipitate obtained in the step (1), drying at 100-120 ℃ for 12-24 hours, raising the temperature to 450-600 ℃ at a heating rate of 1-10 ℃/min, and roasting at the temperature for 4-12 hours to remove organic matter components to obtain mesoporous silica nanospheres with central radial pore canals;

(3) adding an acid solution into a soluble copper salt solution to adjust the pH value of the soluble copper salt solution to be 1-2, then adding the mesoporous silica nanospheres with the central radial pore channels obtained in the step (2) into the soluble copper salt solution after the pH value is adjusted, stirring the solution fully and uniformly, slowly adding an ammonium carbonate solution into the solution to enable the pH value of the slurry to be 6-8, continuing stirring the solution at 500-2000 rpm for 2-6 hours, filtering and washing the obtained product, then drying the product in vacuum at 80-100 ℃ for 12-24 hours, raising the temperature to 450-550 ℃ at the rate of 1-5 ℃/min, and roasting the product at the temperature for 2-8 hours to obtain the mesoporous silica supported copper catalyst with the radial pore channels.

In the above technical scheme, in the step (1), the concentration of the ammonia water is 25% -28%.

In the above technical solution, in the step (1), the organic silicon compound is a mixture of any one, two or more of methyl silicate, ethyl silicate, propyl silicate, butyl silicate, 1, 4-bis (triethoxysilyl) benzene, 1, 2-bis (triethoxysilyl) ethane, (2-cyanoethyl) triethoxysilane, and 3-aminopropyltrimethoxysilane.

In the above technical scheme, in the step (1), the long-chain organic structure directing agent is any one of cetyl trimethyl ammonium bromide, bromocetyl pyridine, cetyl trimethyl ammonium chloride, N-dimethyl hexadecylamine, and sodium hexadecyl trimethyl sulfonate.

In the above technical scheme, in the step (3), the soluble copper salt solution is an aqueous solution of a soluble copper salt, wherein the concentration of the soluble copper salt is 0.2-5.0 mol/L.

In the above technical scheme, in the step (3), the soluble copper salt is any one of copper nitrate, copper chloride, copper sulfate and copper acetate.

In the technical scheme, in the step (3), the acid solution is an acid water solution, wherein the concentration of the acid is 1.0-5.0 mol/L.

In the above technical scheme, in the step (3), the acid is any one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, citric acid, and tartaric acid.

In the above technical solution, in the step (3), the solid-liquid mass ratio of the mesoporous silica nanospheres with the central radial pore channel to the soluble copper salt solution is 1: (4.0-10.0).

In the above technical scheme, in the step (3), the ammonium carbonate solution is an aqueous solution of ammonium carbonate, wherein the concentration of ammonium carbonate is 0.2-1.2 mol/L, and preferably 0.5-1.04 mol/L.

The invention also provides a mesoporous silica supported copper catalyst with a central radial pore passage, which is prepared by the preparation method, wherein the copper content in the catalyst is 10-45% of the total weight of the catalyst, and the content of cuprous in the activated catalyst is 20-60 mol% of the mole number of total active copper; specific surface area of catalyst>500m²G, pore volume>1.0ml/g, and the average mesoporous size is 2.8-10 nm.

The invention also provides an application of the mesoporous silica supported copper catalyst with the central radial pore passage in the reaction of synthesizing ethylene glycol by hydrogenating dimethyl oxalate.

In the technical scheme, when the mesoporous silica supported copper catalyst with the central radial pore canal is applied to the reaction of synthesizing ethylene glycol by hydrogenating dimethyl oxalate, the catalyst is placed in a constant-temperature section of a fixed bed reactor, then a methanol solution of dimethyl oxalate is introduced into a gasification chamber and mixed with hydrogen, the mass ratio of hydrogen to ester is 20-100, and the air speed of hydrogen is 1500-5000 h^-1The reaction is carried out at a hydrogen partial pressure of 1-3 MPa and a reaction temperature of 180-230 ℃.

In the invention, Cu/SiO is prepared by conventional industry by using copper ammonia complex for impregnation and heating to volatilize ammonia₂The catalyst method has many disadvantages, such as large ammonia gas volatile smell, environmental pollution, difficult control of synthesis process conditions, careful monitoring in the whole process, easy inactivation of the prepared single metal copper catalyst, and the like. The invention develops a method for preparing the Cu/SiO2 catalyst by using (NH4)2CO3 as a precipitator, not only reduces the environmental pollution, but also has excellent catalyst performance and good stability, can realize automatic operation, and is suitable for the requirement of large-scale industrial production.

In the invention, Cu is added in the process of dimethyl oxalate hydrogenation reaction⁰Active siteMainly plays a role in activating H₂Action of molecules, and Cu⁺The active site plays a role in polarizing and activating ester groups in the dimethyl oxalate, and the high conversion rate of the dimethyl oxalate hydrogenation reaction and the high selectivity of a target product are realized by the synergistic effect of the active site and the ester groups. During the reaction process, Cu is influenced by factors such as the increase of the agglomeration of copper particles and the change of metal-carrier interaction⁰/Cu⁺The ratio of (A) to (B) also varies greatly, and once the synergy is destroyed, the catalytic activity of the catalyst is reduced sharply, and the catalyst is apparently deactivated. In the sol-gel method preparation, under the same experimental conditions, when the copper loading capacity is increased, the main factors influencing the catalyst activity are the wrapping of copper species by silicon dioxide and the agglomeration of copper species, so that the surface area of the copper species on the surface of the catalyst is reduced and the catalyst activity is reduced. The preparation method of the catalyst provided by the invention can improve the loading capacity of the copper active component and the dispersity of the copper active component, reduce the diffusion resistance of reactant molecules and products on the catalyst, undoubtedly improve the conversion rate of dimethyl oxalate reaction and the selectivity of ethylene glycol products, reduce the inactivation rate and prolong the service life of the catalyst.

The invention aims to provide the catalyst for synthesizing the ethylene glycol by hydrogenating the dimethyl oxalate, which has the advantages of high activity, simple preparation process, low cost and environmental friendliness, wherein the conversion rate of the dimethyl oxalate can reach more than 99 percent, the selectivity of the ethylene glycol can reach more than 96 percent, and the catalyst is stable in reaction and easy to control.

Drawings

FIG. 1 is an SEM image of silica nanospheres prepared in example 1 and having a central radial mesoporous structure.

Detailed Description

The following detailed description of the embodiments of the present invention is provided, but the present invention is not limited to the following descriptions:

example 1

A silicon oxide nanosphere loaded copper catalyst with a radial mesoporous center is prepared by the following method:

(1) mixing 142.3g of diethyl ether, 75.2g of ethanol, 4.78g of 28% ammonia water and 438.8g of distilled water to form a uniform solution, adding 4.20g of cetyltrimethylammonium bromide (CTAB) and stirring at room temperature and 1000rpm for 1 hour, quickly dropwise adding 20g of ethyl silicate (TEOS) into the mixture, stirring at 800rpm for 2 hours, and heating to 50 ℃ for reaction for 12 hours; obtaining white precipitate;

(2) filtering and washing the white precipitate obtained in the step (1), drying at 105 ℃ for 24 hours, raising the temperature to 500 ℃ at the heating rate of 2 ℃/min, roasting for 6 hours, and removing organic components to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals, as shown in figure 1;

(3) in 200ml of Cu (NO) with a concentration of 0.40mol/L₃)₂Adding 5.0mol/L nitric acid solution into the solution to adjust the pH value to 1.0, adding 20g of mesoporous silica nanospheres (DMSNs) with central radial pore canals obtained in the step (2), stirring at the rotating speed of 600rpm, and slowly adding (NH) with the concentration of 0.5mol/L₄)₂CO₃And (3) saturating the solution until the pH value of the slurry is 6, continuously stirring for 6 hours at the rotating speed of 600rpm, filtering and washing the obtained product, drying for 12 hours at the temperature of 80 ℃ in vacuum, raising the temperature to 450 ℃ at the heating rate of 1 ℃/min, roasting for 6 hours to obtain a finished catalyst, and obtaining the finished catalyst, wherein the mass fraction of Cu is 20.2 wt% by XRF quantitative analysis and is marked as CuDMS-1. The types of raw materials for preparation and analytical data of the catalyst are shown in tables 1 and 2.

Example 2

(1) mixing 175.3g of diethyl ether, 96.8g of ethanol, 9.57g of 26% ammonia water and 721.3g of distilled water to form a uniform solution, adding 4.04g of bromohexadecylpyridine, stirring at the rotating speed of 1500rpm for 1 hour at room temperature, quickly dropwise adding 20g of methyl silicate into the mixture, stirring at the rotating speed of 1500rpm for 2 hours, and heating to 60 ℃ for reacting for 6 hours to obtain white precipitates;

(2) filtering, washing and drying the white precipitate obtained in the step (1) at 120 ℃ for 12 hours, raising the temperature to 550 ℃ at the heating rate of 5 ℃/min, roasting for 4 hours, and removing organic components to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals;

(3) in 200ml of Cu (CH) with a concentration of 0.94mol/L₃COO)₂Adding 2.5mol/L hydrochloric acid solution into the solution to adjust pH value to 1.0, adding 20g of mesoporous silica nanospheres (DMSNs) with central radial pore canals obtained in the step (2), stirring at the rotation speed of 1800rpm, and slowly adding (NH) with concentration of 0.8mol/L₄)₂CO₃And (3) continuing stirring the solution for 2 hours at the rotation speed of 1800rpm until the pH value of the slurry is 7, filtering and washing the obtained product, drying the product in vacuum at the temperature of 80 ℃ for 12 hours, raising the temperature to 500 ℃ at the heating rate of 2 ℃/min, roasting the product for 4 hours to obtain a finished catalyst, and obtaining the finished catalyst, wherein the mass fraction of Cu is 37.4 wt% by XRF quantitative analysis and is marked as CuDMS-2. The types of raw materials for preparation and analytical data of the catalyst are shown in tables 1 and 2.

Example 3

(1) 158.6g of ethyl ether, 91.3g of ethanol, 6.89g of 25% ammonia water and 449.3g of distilled water are mixed to form a uniform solution, 3.63g of cetyltrimethylammonium chloride is added and stirred at the rotation speed of 1200rpm for 1 hour at room temperature, 20g of propyl silicate is quickly added dropwise to the mixture and stirred at the rotation speed of 1200rpm for 2 hours, and the mixture is heated to 60 ℃ to react for 10 hours to obtain white precipitate;

(2) filtering, washing and drying the white precipitate obtained in the step (1) at 120 ℃ for 12 hours, raising the temperature to 550 ℃ at the heating rate of 2 ℃/min, roasting for 4 hours, and removing organic components to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals;

(3) in 200ml of Cu (NO) with a concentration of 0.68mol/L₃)₂Adding 50 wt% nitric acid solution into the solution to adjust pH value to 1.0, adding into the mesoporous silica nanospheres (DMSNs) obtained in step (2) to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals, stirring at 1500rpm, and slowly adding (NH) with concentration of 1.0mol/L₄)₂CO₃Saturating the solution until the pH value of the slurry is 6, continuing stirring at the rotating speed of 1500rpm for 4 hours, filtering and washing the obtained productWashing, drying in vacuum at 90 ℃ for 12 hours, raising the temperature to 500 ℃ at the heating rate of 2 ℃/min, roasting for 4 hours to obtain a finished catalyst, and obtaining the Cu with the mass fraction of 30.3 wt% by XRF quantitative analysis, wherein the mass fraction is recorded as CuDMS-3. The types of raw materials for preparation and analytical data of the catalyst are shown in tables 1 and 2.

Example 4

(1) mixing 137.0g of diethyl ether, 73.9g of ethanol, 4.22g of 28% ammonia water and 290.6g of distilled water to form a uniform solution, adding 2.68g N, stirring N-dimethylhexadecylamine at the rotating speed of 1400rpm at room temperature for 1 hour, quickly dropwise adding 20g of 1, 4-bis (triethoxysilyl) benzene into the mixture, stirring at the rotating speed of 1400rpm for 2 hours, and heating to 45 ℃ to react for 24 hours to obtain white precipitates;

(2) filtering and washing the white precipitate obtained in the step (1), drying at 110 ℃ for 24 hours, raising the temperature to 500 ℃ at the heating rate of 1 ℃/min, roasting for 4 hours, and removing organic components to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals;

(3) in 200ml of 1.03mol/L CuCl₂Adding 3.5mol/L acetic acid solution into the solution to adjust the pH value to 1.0, adding 20g of mesoporous silica nanospheres (DMSNs) with central radial pore canals obtained in the step (2), stirring at the rotating speed of 1800rpm, and slowly adding (NH) with the concentration of 1.04mol/L₄)₂CO₃And (3) saturating the solution until the pH value of the slurry is 6, continuing stirring at the rotation speed of 1800rpm for 2 hours, filtering and washing the obtained product, drying at 90 ℃ in vacuum for 12 hours, raising the temperature to 500 ℃ at the heating rate of 2 ℃/min, roasting for 4 hours to obtain a finished catalyst, and quantitatively analyzing by XRF to obtain the Cu mass fraction of 39.5 wt%, which is recorded as CuDMS-4. The types of raw materials for preparation and analytical data of the catalyst are shown in tables 1 and 2.

Example 5

(1) 168.5g of diethyl ether, 89.5g of ethanol, 4.19g of 27% ammonia water and 480.4g of distilled water are mixed to form a uniform solution, 6.01g of bromohexadecylpyridine is added to the uniform solution and stirred at the rotating speed of 1800rpm for 0.5 hour at room temperature, 20g of (2-cyanoethyl) triethoxysilane is quickly dripped into the mixture and stirred at the rotating speed of 1800rpm for 1.5 hours, and the mixture is heated to 60 ℃ and reacted for 5 hours to obtain white precipitates;

(2) filtering, washing and drying the white precipitate obtained in the step (1) at 120 ℃ for 12 hours, raising the temperature to 500 ℃ at the heating rate of 1 ℃/min, roasting for 4 hours, and removing organic components to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals;

(3) in 200ml of CuSO with the concentration of 0.54mol/L₄Adding 50 wt% nitric acid solution into the solution to adjust pH to 1.0, adding into the mesoporous silica nanospheres (DMSNs) obtained in step (2) to obtain mesoporous silica nanospheres (DMSNs) with central radial pore canals, stirring at 800rpm, and slowly adding into the solution (NH4) with concentration of 0.6mol/L₂CO₃And (3) saturating the solution until the pH value of the slurry is 6, continuing stirring for 6 hours at the rotating speed of 800rpm, filtering and washing the obtained product, drying for 12 hours in vacuum at the temperature of 90 ℃, raising the temperature to 500 ℃ at the heating rate of 2 ℃/min, roasting for 4 hours to obtain a finished catalyst, and quantitatively analyzing by XRF to obtain the Cu mass fraction of 25.4 wt%, which is recorded as CuDMS-5. The types of raw materials for preparation and analytical data of the catalyst are shown in tables 1 and 2.

Example 6

(1) 356.4g of diethyl ether, 197.3g of ethanol, 9.14g of 28% ammonia water and 702.8g of distilled water are mixed to form a uniform solution, 6.60g of sodium hexadecyl trimethyl sulfonate is added and stirred for 1 hour at room temperature under the rotating speed of 1600rpm, 20g of 3-aminopropyl trimethoxy silane is quickly and dropwise added into the mixture and stirred for 2 hours under the rotating speed of 1600rpm, and the mixture is heated to 60 ℃ to react for 6 hours to obtain white precipitate;

(3) in 200ml of Cu (NO) with a concentration of 1.22mol/L₃)₂Adding 1.5mol/L citric acid solution into the solution to adjust pH to 1.0, adding 20g of mesoporous silica nanospheres (DMSNs) with central radial pore canal obtained in step (2), stirring at 1000rpm, and slowly adding 0.5mol/L (NH4)₂CO₃And (3) saturating the solution until the pH value of the slurry is 6, continuously stirring for 4 hours at the rotating speed of 1000rpm, filtering and washing the obtained product, drying for 12 hours at the temperature of 90 ℃ in vacuum, raising the temperature to 500 ℃ at the heating rate of 2 ℃/min, roasting for 4 hours to obtain a finished catalyst, and obtaining the Cu finished product, wherein the weight fraction of Cu is 43.6 wt% measured by XRF quantitative analysis and is recorded as CuDMS-6. The types of raw materials for preparation and analytical data of the catalyst are shown in tables 1 and 2.

Comparative example 1: the catalyst was prepared according to the method described in the example of patent CN 103816915A:

7.6g of Cu (NO)₃)₂·3H₂Dissolving O in 500ml of deionized water to form a solution, adjusting the pH value of the solution to 2-3 by using nitric acid, adding 10g of urea, and then adding 7.89g of mesoporous SiO₂Support (HMS), stirred vigorously for 4 hours to form a mixed solution.

The three-necked flask containing the mixed solution was put in an oil bath at 90 ℃ and stirred, and heated to reflux the vapor. The pH value of the solution gradually rises along with the decomposition of the urea, stirring is stopped when the pH value of the solution rises to 7.0, the solution is filtered while the solution is hot, the obtained filter cake (precipitate) is washed by deionized water, the precipitate is dried at 120 ℃ for 12 hours, then the dried precipitate is moved to a muffle furnace, the temperature is raised to 450 ℃ at the speed of 1 ℃/min under the air atmosphere, and then the dried precipitate is roasted at constant temperature for 4 hours, so that the Cu/HMS catalyst with the copper mass percentage content of 20.3 percent is obtained, and the Cu/HMS catalyst is marked as CuSiVS-1.

Comparative example 2: the catalyst was prepared according to the procedure described in the example of patent CN 10656449A:

dissolving 10.6g of copper nitrate and 0.5g of mannitol in 100g of distilled water, fully dissolving, and then placing in an ultrasonic instrument for ultrasonic oscillation for 20min, wherein the ultrasonic frequency is 25 kHz. 5.0g of urea was added to the above solution and dissolved by stirring, and then 20m of 1 m of ammonia water was added thereto and stirred sufficiently for 30 min. Finally, 21g of an alkaline silica sol containing 40% SiO2 was added dropwise, the mixture was mechanically stirred and placed in a water bath at 80 ℃ for 5 hours, and heating was stopped until the pH of the solution reached approximately 7. And filtering to obtain a filter cake, washing the filter cake with distilled water for multiple times, drying the obtained filter cake in air at 120 ℃ for 24 hours, and roasting at 450 ℃ for 4 hours in an air atmosphere to obtain the Cu/SiO2 catalyst, wherein the mass fraction of Cu is 24.9 wt%, and the catalyst is recorded as CuSiVS-2.

TABLE 1 compositions of the materials in the different examples

TABLE 2 physicochemical Properties of the catalysts in the different examples and comparative examples

The application example is as follows: the application of the catalysts obtained in examples 1 to 6 and comparative examples 1 to 2 was examined:

respectively taking 10ml of the catalysts obtained in the examples 1-6 and the comparative examples 1-2 and filling the catalysts into a tubular reactor; the reaction tube is heated to 250 ℃ from room temperature at the speed of 2 ℃/min, the hydrogen content is gradually increased to 100 percent from 10 percent, after the temperature of the reaction tube is heated to 250 ℃, the reaction tube is reduced for 5 hours by hydrogen with the flow rate of 50m1/(min ml cat.)99.99 percent, and the reduction pressure is 1.2 MPa; then the prepared 0.2g/ml dimethyl oxalate methanol solution is introduced into a gasification chamber and mixed with hydrogen. Dimethyl oxalate is taken as a raw material, and the hydrogen/ester molar ratio is 50: 1, the space velocity of hydrogen is 2000h < -1 >, the reaction temperature is controlled to be 180-230 ℃, the reaction pressure is about 2.0MPa, the operation is carried out for 48 hours, various data of the catalyst are measured, and the result is shown in a table 3, wherein DMO represents dimethyl oxalate, EG represents ethylene glycol, and MG represents methyl glycolate.

Table 3: catalytic performance of the catalysts in the different examples and comparative examples

As can be seen from the analysis of Table 3, the catalyst prepared by the embodiment of the invention has the conversion rate of more than 99 percent and the selectivity of ethylene glycol of more than 96 percent in the hydrogenation reaction of dimethyl oxalate; in the reaction of the catalyst obtained in the comparative example under the same conditions, the conversion rate of dimethyl oxalate is less than 99 percent, and the selectivity of ethylene glycol is less than 87 percent; this demonstrates the significant advantages of the catalysts prepared according to the invention.

The above examples are only for illustrating the technical concept and features of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a mesoporous silica supported copper catalyst with a central radial pore passage is characterized by comprising the following steps:

(1) mixing diethyl ether, ethanol, ammonia water and water to form a uniform solution, adding a long-chain structure guiding agent into the uniform solution, stirring at the room temperature at 500-2000 rpm for 0.5-2 hours to form a mixture, quickly dripping an organic silicon compound into the mixture, stirring at the 500-2000 rpm for 0.5-2 hours, heating to 40-60 ℃, reacting for 4-24 hours, and forming a white precipitate; in the obtained white precipitate, the molar ratio of the materials is as follows: SiO2₂: diethyl ether: ethanol: long chain structure directing agent: NH (NH)₃：H₂O＝1：(15～45)：(15～40)：(0.08～0.2)：(0.5～1.5)：(250～350)；

2. The method according to claim 1, wherein the concentration of the aqueous ammonia in the step (1) is 25 to 28%.

3. The method according to claim 1, wherein in the step (1), the organosilicon compound is a mixture of one, two or more selected from the group consisting of methyl silicate, ethyl silicate, propyl silicate, butyl silicate, 1, 4-bis (triethoxysilyl) benzene, 1, 2-bis (triethoxysilyl) ethane, (2-cyanoethyl) triethoxysilane, and 3-aminopropyltrimethoxysilane.

4. The method according to claim 1, wherein in step (1), the long-chain organic structure-directing agent is any one of cetyltrimethylammonium bromide, cetylpyridinium bromide, cetyltrimethylammonium chloride, N-dimethylhexadecylamine, and sodium hexadecyltrimethylammonium sulfonate.

5. The method according to claim 1, wherein in the step (3), the soluble copper salt solution is an aqueous solution of a soluble copper salt, wherein the concentration of the soluble copper salt is 0.2-5.0 mol/L; the soluble copper salt is any one of copper nitrate, copper chloride, copper sulfate and copper acetate.

6. The preparation method according to claim 1, wherein in the step (3), the acid solution is an aqueous acid solution, wherein the acid concentration is 1.0-5.0 mol/L; the acid is any one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, citric acid and tartaric acid.

7. The preparation method according to claim 1, wherein in the step (3), the solid-liquid mass ratio of the mesoporous silica nanospheres with the central radial pore channels to the soluble copper salt solution is 1: (4.0-10.0).

8. The preparation method according to claim 1, wherein in the step (3), the ammonium carbonate solution is an aqueous solution of ammonium carbonate, and the concentration of ammonium carbonate is 0.2-1.2 mol/L.

9. The mesoporous silica supported copper catalyst with the central radial pore channels prepared by the preparation method of any one of claims 1 to 8 is characterized in that the copper content in the catalyst is 10-45% of the total weight of the catalyst, and the monovalent copper content in the activated catalyst is 20-60 mol% of the total active copper; specific surface area of catalyst>500m²G, pore volume>1.0ml/g, and the average mesoporous size is 2.8-10 nm.

10. The use of the mesoporous silica supported copper catalyst with central radial channels according to claim 9 in the hydrogenation of dimethyl oxalate to ethylene glycol.