阅读说明：本技术 一种马来酸二甲酯加氢反应催化剂及其制备方法和应用 (Dimethyl maleate hydrogenation reaction catalyst, and preparation method and application thereof ) 是由 陈玮 刘千河 梁培彤 赖玉龙 连虎强 王士振 徐晓飞 邢培智 于 2021-08-20 设计创作，主要内容包括：本发明属于化工制品技术领域,具体涉及一种马来酸二甲酯加氢反应催化剂及其制备方法和应用。本发明所述催化剂中各元素的摩尔百分比为：Cu 30～40％,Mn 20～30％,Al 10～20％,Zn 10～20％,Ag 0～5%,Ru 0～5%。本发明通过在催化剂中添加Al元素、Ag元素和Ru元素,实现了对催化剂中活性组分的分散、修饰,BDO与γ-丁内酯选择性总共可达93%,可有效降低成本,且绿色环保。本发明所述催化剂在马来酸二甲酯加氢反应催化剂制备1,4-丁二醇的过程中可以通过改变反应条件的方式分别高选择性地制备1,4-丁二醇和/或γ-丁内酯。本发明所述催化剂的制备方法简单、且成本低廉,所制备的催化剂不仅环保而且具有较长的使用寿命。(The invention belongs to the technical field of chemical products, and particularly relates to a dimethyl maleate hydrogenation reaction catalyst, and a preparation method and application thereof. The mole percentage of each element in the catalyst is as follows: 30-40% of Cu, 20-30% of Mn, 10-20% of Al, 10-20% of Zn, 0-5% of Ag and 0-5% of Ru. According to the invention, Al element, Ag element and Ru element are added into the catalyst, so that the dispersion and modification of active components in the catalyst are realized, the selectivity of BDO and gamma-butyrolactone can reach 93% in total, the cost can be effectively reduced, and the catalyst is green and environment-friendly. The catalyst can be used for preparing 1, 4-butanediol and/or gamma-butyrolactone in a high-selectivity manner by changing reaction conditions in the process of preparing 1, 4-butanediol by using the dimethyl maleate hydrogenation catalyst. The preparation method of the catalyst is simple and low in cost, and the prepared catalyst is environment-friendly and has a long service life.)

1. A dimethyl maleate hydrogenation reaction catalyst is characterized in that the mole percentage of each element in the catalyst is as follows: 30-40% of Cu, 20-30% of Mn, 10-20% of Al, 10-20% of Zn, 0-5% of Ag and 0-5% of Ru.

2. The process for preparing a catalyst for the hydrogenation of dimethyl maleate as claimed in claim 1, which comprises the steps of:

(1) mixing a Cu soluble salt solution, a Zn soluble salt solution and a Mn soluble salt solution to obtain a mixed solution, carrying out coprecipitation reaction on the mixed solution and a precipitator at the temperature of 70-90 ℃, and controlling the total concentration of Cu, Mn and Zn metal ions to be 0.7-1.3M; the concentration of the precipitant is 0.8-1.8M, the pH value of a precipitation system is kept at 6.8-7.2, after the reaction is finished, stirring is carried out at a constant temperature for 90-120 min, and solid-liquid separation is carried out to obtain a Cu-Mn-Zn-O precipitate;

(2) adding aluminum hydroxide, silver nitrate, ruthenium chloride and deionized water into the precipitate obtained in the step (1), heating to 70-90 ℃, and reacting for 55-65min to obtain a solid product;

(3) and (3) drying the solid product obtained in the step (2) at 100-130 ℃, roasting at 350-450 ℃ for 8-12h, tabletting, and granulating to obtain the catalyst product.

3. The method according to claim 2, wherein the total concentration of the three metal ions of Cu, Mn and Zn is 0.9-1.1M during the coprecipitation reaction in step (1).

4. The preparation method according to claim 2, wherein hydrogen peroxide is added as a pore-enlarging agent during the coprecipitation reaction of the mixed solution and the precipitant solution in step (1).

5. The preparation method according to claim 2, wherein the adding amount of the aluminum hydroxide in the step (2) is 10-30% of the total mole number of the three metal ions of Cu, Mn and Zn in the mixed solution; the adding amount of silver nitrate is 1-5% of the total mole number of the three metal ions of Cu, Mn and Zn in the mixed solution; the addition amount of the ruthenium chloride is 1-5% of the total mole number of the three metal ions of Cu, Mn and Zn in the mixed solution.

6. The preparation method according to claim 2, wherein the volume of the deionized water added in the step (2) is 80-120% of the total volume of the mixed solution and the precipitant in the step (1).

7. The production method according to claim 2, wherein the soluble salt solution of Cu, the soluble salt solution of Zn, and the soluble salt of Mn is any one of nitrate, acetate, oxalate; the precipitant is any one of sodium hydroxide, sodium carbonate, ammonia water and oxalic acid.

8. Use of the dimethyl maleate hydrogenation catalyst of claim 1 in the preparation of 1, 4-butanediol.

9. A method for preparing 1, 4-butanediol by using the catalyst for hydrogenation of dimethyl maleate as claimed in claim 1, which comprises the steps of:

a. activation of the catalyst: putting the catalyst into a reaction tube for reduction activation treatment;

b. catalytic hydrogenation of dimethyl maleate: and (b) placing the dimethyl maleate into the reaction tube in the step (a), carrying out catalytic reaction under the conditions of the pressure of 3-5 MPa and the temperature of 170-200 ℃, and collecting the reaction product after condensation.

10. The method of claim 9, wherein the catalytic reaction pressure in step b is 4MPa, and the reaction temperature is 180 ℃; the feed rate of dimethyl maleate in step b is from 1 to 2 g/h.

Technical Field

The invention belongs to the technical field of chemical products, and particularly relates to a dimethyl maleate hydrogenation reaction catalyst, and a preparation method and application thereof.

Background

The 1, 4-butanediol is also called BDO, has numerous downstream derivatives, is not only widely used for the production of solvents, medicines, cosmetics, plasticizers, curing agents, pesticides and the like, but also can be used for preparing chemical preparations such as tetrahydrofuran, polydioxanyl succinate, gamma-butyrolactone, N-methyl pyrrolidone and the like, and is an important chemical raw material.

At present, the synthesis method of 1, 4-butanediol mainly comprises the following steps: an alkynal method (Reppe method), a maleic anhydride (maleic anhydride) method, an acrylic method, a butadiene method, and the like. The synthesis route of the maleic anhydride method is to prepare 1, 4-butanediol by hydrogenating raw material maleic anhydride or dialkyl maleate (such as dimethyl maleate) by a two-step method. The reaction for preparing 1, 4-butanediol by adopting dialkyl maleate is a gas-phase hydrogenation reaction taking a copper catalyst as a main catalyst. Common copper-based catalysts include chromium-containing type catalysts and chromium-free type catalysts.

The prior art does not lack an example of improving the process conditions of the gas-phase hydrogenation catalytic reaction of dialkyl maleate and an example of improving the catalyst structure so as to realize the high-yield co-production of various products.

For example, patent US5698749 discloses a catalyst with palladium-rhenium supported on a carbon carrier, which enables the conversion of dimethyl maleate to 100% at a temperature of 160 ℃ under 17.3MPa and under hydrogen carrier gas conditions, but the selectivity to 1, 4-butanediol and tetrahydrofuran is not high, the selectivity to 1, 4-butanediol is only 82.3% and the selectivity to tetrahydrofuran is only 6.5%.

For another example, patent CN101502803B discloses a catalyst for preparing 1, 4-butanediol by selective hydrogenation of dimethyl maleate, the catalyst uses copper, zinc and aluminum as main elements, and by adding manganese, magnesium or chromium, the yield of 1, 4-butanediol prepared by hydrogenation can reach 73.6% at the reaction temperature of 180 ℃, and the yield of tetrahydrofuran prepared by hydrogenation can reach 96% at the reaction temperature of 220 ℃, and the selectivity of the method to BDO and γ -butyrolactone is low.

For another example, patent CN1356168A discloses a catalyst for preparing 1, 4-butanediol and tetrahydrofuran by gas phase hydrogenation of dimethyl maleate, which selects copper, manganese, aluminum and nickel as main catalyst elements to achieve a selectivity of 1, 4-butanediol of more than 80% in the reaction of preparing 1, 4-butanediol by catalysis, but the selectivity of 1, 4-butanediol is not high due to the coproduction of tetrahydrofuran in the method.

In conclusion, most of the existing dialkyl maleate gas-phase hydrogenation catalytic processes produce three main products, namely BDO, gamma-butyrolactone and tetrahydrofuran, simultaneously, but because the economic value of BDO and gamma-butyrolactone in the dialkyl maleate gas-phase hydrogenation catalytic reaction product is high and the value of byproduct tetrahydrofuran is not high, such gas-phase hydrogenation catalytic processes are not only poor in selectivity, but also easily produce excessive byproduct tetrahydrofuran, resulting in waste of productivity.

Therefore, the application is based on the technical problems in the prior art, and improves the reaction for preparing 1, 4-butanediol by gas-phase hydrogenation of dialkyl maleate (such as dimethyl maleate), and mainly adjusts the catalyst structure in the reaction process to achieve the aim of preparing a catalyst which has high selectivity, high activity, strong adaptability, reusability and regeneration.

Disclosure of Invention

The invention aims to provide a dimethyl maleate hydrogenation catalyst, which is characterized in that Al element, Ag element and Ru element are added in the catalyst to improve the activity and stability of the catalyst, the selectivity of BDO and gamma-butyrolactone can reach 93 percent in total, the cost can be effectively reduced, and the catalyst is green and environment-friendly.

The invention also provides the application of the catalyst in preparing 1, 4-butanediol.

Based on the purpose, the invention adopts the following technical scheme:

a dimethyl maleate hydrogenation reaction catalyst comprises Cu, Mn, Al, Zn, Ag and Ru elements, wherein the mole percentage of each element is as follows: 30-40% of Cu, 20-30% of Mn, 10-20% of Al, 10-20% of Zn, 0-5% of Ag and 0-3% of Ru.

A preparation method of a dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) mixing a Cu soluble salt solution, a Zn soluble salt solution and a Mn soluble salt solution to obtain a mixed solution, carrying out concurrent flow titration on the mixed solution and a precipitator at the temperature of 70-90 ℃ to carry out coprecipitation reaction, and controlling the total concentration of Cu, Mn and Zn metal ions to be 0.7-1.3M; the concentration of the precipitant is 0.8-1.8M, the pH value of a precipitation system is kept at 6.8-7.2, after the dropwise addition is finished, the stirring is carried out at constant temperature for 90-120 min, the solid-liquid separation is carried out, and then the washing is carried out by clear water, so as to obtain a Cu-Mn-Zn-O precipitate;

(2) adding aluminum hydroxide, silver nitrate, ruthenium chloride and deionized water into the precipitate obtained in the step (1), heating to the coprecipitation reaction temperature (70-90 ℃) of the mixed solution in the step (1), and stirring for reacting for 55-65min to obtain a solid product;

(3) and (3) drying the solid product obtained in the step (2) at 100-130 ℃, roasting at 350-450 ℃ for 8-12h, tabletting, and granulating to obtain the catalyst product.

Specifically, during the coprecipitation reaction in the step (1), the total concentration of three metal ions, namely Cu, Mn and Zn, is 0.9-1.1M.

Further preferably, in the step (1), during the coprecipitation reaction of the mixed solution and the precipitant solution, hydrogen peroxide is added as a pore-expanding agent, the pore-expanding agent can change the pores of the catalyst, so that the service life of the catalyst can be prolonged, and the pores can be formed between the pores of the catalyst by the hydrogen peroxide in a physical manner, so that the stability of the catalyst is improved, and meanwhile, the catalyst is more favorable for energy conservation and environmental protection.

Specifically, the adding amount of the aluminum hydroxide in the step (2) is 10-30% of the total mole number of the three metal ions of Cu, Mn and Zn in the mixed solution; the adding amount of silver nitrate is 1-5% of the total mole number of the three metal ions of Cu, Mn and Zn in the mixed solution; the addition amount of the ruthenium chloride is 1-5% of the total mole number of the three metal ions of Cu, Mn and Zn in the mixed solution.

Specifically, the volume of the deionized water added in the step (2) is 80-120% of the total volume of the mixed solution and the precipitator in the step (1).

Further, the Cu soluble salt solution, the Zn soluble salt solution, and the Mn soluble salt may be any one of nitrate, acetate, and oxalate, but do not contain Cl and S ions.

Further, the precipitant may be any one of sodium hydroxide, sodium carbonate, ammonia water, and oxalic acid.

Further, the catalyst with the Cu-Mn-Al-Zn-Ag-Ru-O element prepared by the steps consists of active components of copper, manganese oxide, aluminum oxide, zinc oxide, silver oxide and ruthenium oxide. In the catalyst with Cu-Mn-Al-Zn-Ag-Ru-O elements, the dispersion and modification effects of the active components are realized through the metal oxides in the catalyst. The catalyst is used for dimethyl maleate hydrogenation reaction, and can respectively prepare 1, 4-butanediol and/or gamma-butyrolactone with high selectivity.

Further, the invention also provides application of the dimethyl maleate hydrogenation catalyst in preparation of 1, 4-butanediol.

Further preferably, the invention also provides a method for preparing 1, 4-butanediol by using the dimethyl maleate hydrogenation catalyst, which specifically comprises the following steps:

a. activation of the catalyst: granulating the roasted catalyst powder to 40-60 meshes, and placing the granulated catalyst powder into a reaction tube of a fixed bed reactor for reduction activation treatment;

b. catalytic hydrogenation of dimethyl maleate: and (b) placing the dimethyl maleate into the reaction tube in the step (a), carrying out catalytic reaction under the conditions of the pressure of 3-5 MPa and the temperature of 170-200 ℃, and collecting the reaction product after condensation.

Preferably, the catalytic reaction pressure in the step b is 4MPa, and the reaction temperature is 180 ℃.

Preferably, the feed rate of dimethyl maleate in step b is from 1 to 2 g/h.

Compared with the prior art, the invention has the following advantages:

1. the preparation method of the catalyst is simple and low in cost, and the prepared catalyst is environment-friendly and has a long service life.

2. The invention improves the copper catalyst in the synthesis reaction of 1, 4-butanediol, and realizes the dispersion and modification of active components in the catalyst by adding Al element, Ag element and Ru element, thereby improving the activity of the catalyst.

3. The catalyst can be used for preparing 1, 4-butanediol and/or gamma-butyrolactone in a high-selectivity manner by changing reaction conditions in the process of preparing 1, 4-butanediol by using the dimethyl maleate hydrogenation catalyst.

The catalyst prepared by the invention has high catalytic activity and good selectivity, the selectivity to BDO and gamma-butyrolactone can reach 93 percent in total, the production cost can be effectively reduced, the phenomenon that a plurality of products are produced simultaneously during gas phase hydrogenation catalytic reaction of dialkyl maleate in the prior art, so that the byproducts are excessive is avoided, and the catalyst has good industrial application prospect.

Detailed Description

In order to make the technical purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are further described with reference to specific examples, which are intended to explain the present invention and are not to be construed as limiting the present invention, and those who do not specify a specific technique or condition in the examples follow the techniques or conditions described in the literature in the art or follow the product specification.

Example 1

This example prepares a catalyst containing Cu, Mn, Al, and Zn elements for a hydrogenation reaction of dimethyl maleate, where the mole percentages of the elements are: cu: 39.8%, Mn: 26.86%, Zn: 16.91%, Al: 16.43 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) 12.0g of Cu (NO)₃)₂·3H₂O、6g Mn(NO₃)₂And 4g Zn (NO)₃)₂·6H₂O in 200ml H₂Preparing a metal ion mixed solution by using O; 18g of Na₂CO₃Dissolved in 200ml of H₂Preparing a precipitant solution from O;

(2) in a water bath at 80 ℃, dropwise adding a metal ion mixed solution and a precipitant solution in a cocurrent flow manner to perform coprecipitation reaction, stirring while dropwise adding, keeping the pH value of a precipitation system at 6.8, stirring for 90min at a constant temperature after dropwise adding is finished, and then washing with clear water to remove impurity ions to obtain a Cu-Mn-Zn-O precipitate;

(3) to the precipitate in the step (2) was added 1.6g of Al (OH)₃Obtaining a blend, then adding 300ml of deionized water into the blend, heating to 80 ℃, and stirring for 60 min;

(4) and (4) carrying out suction filtration on the blend in the step (3), carrying out solid-liquid separation, drying the obtained filter cake at 120 ℃ for 12h, and then heating to 400 ℃ in a muffle furnace to roast for 10h to obtain the catalyst 1 containing no Ag or Ru.

Example 2

This example prepares a catalyst containing elements Cu, Mn, Al, Zn, and Ag for a hydrogenation reaction of dimethyl maleate, where the mole percentages of the elements are: cu: 38.86%, Mn: 26.23%, Zn: 16.51%, Al: 16.04%, Ag: 2.35 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) 12.0g of Cu (NO)₃)₂·3H₂O、6g Mn(NO₃)₂And 4g Zn (NO)₃)₂·6H₂O in 200ml H₂Preparing a metal ion mixed solution by using O; 18g of Na₂CO₃Dissolved in 200ml of H₂O is preparedForming a precipitant solution;

(2) in a water bath at 80 ℃, dropwise adding a metal ion mixed solution and a precipitant solution in a cocurrent flow manner to perform coprecipitation reaction, stirring while dropwise adding, keeping the pH value of a precipitation system at 7, stirring at a constant temperature for 100min after dropwise adding is finished, and then washing with clear water to remove impurity ions to obtain a Cu-Mn-Zn-O precipitate;

(3) to the precipitate in the step (2) was added 1.6g of Al (OH)₃And 0.5g AgNO₃Obtaining a blend, then adding 300ml of deionized water into the blend, heating to 80 ℃, and stirring for 60 min;

(4) and (4) carrying out suction filtration on the blend in the step (3), carrying out solid-liquid separation, drying the obtained filter cake at 120 ℃ for 12h, heating to 400 ℃ in a muffle furnace, and roasting for 10h to obtain the catalyst 2 containing Ag2.35%.

Example 3

The embodiment prepares a dimethyl maleate hydrogenation catalyst containing elements of Cu, Mn, Al, Zn, and Ru, wherein the mole percentages of the elements are as follows: cu: 39.17%, Mn: 26.44%, Zn: 16.64%, Al: 16.17%, Ru: 1.58 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) 12.0g of Cu (NO)₃)₂·3H₂O、6g Mn(NO₃)₂And 4g Zn (NO)₃)₂·6H₂O in 200ml H₂Preparing a metal ion mixed solution by using O; 18g of Na₂CO₃Dissolved in 200ml of H₂Preparing a precipitant solution from O;

(2) in a water bath at 80 ℃, dropwise adding a metal ion mixed solution and a precipitant solution in a cocurrent flow manner to perform coprecipitation reaction, stirring while dropwise adding, keeping the pH value of a precipitation system at 7, stirring at a constant temperature for 100min after dropwise adding is finished, and then washing with clear water to remove impurity ions to obtain a Cu-Mn-Zn-O precipitate;

(3) to the precipitate in the step (2) was added 1.6g of Al (OH)₃And 0.4g RuCl₃Obtaining a blend, then adding 300ml of deionized water into the blend, heating to 80 ℃, and stirring for 60 min;

(4) and (4) carrying out suction filtration on the blend in the step (3), carrying out solid-liquid separation, drying the obtained filter cake at 120 ℃ for 12h, and then heating to 400 ℃ in a muffle furnace to roast for 10h to obtain the Ru1.58% catalyst 3.

Example 4

The embodiment prepares a dimethyl maleate hydrogenation catalyst containing elements of Cu, Mn, Al, Zn, Ag, and Ru, wherein the mole percentages of the elements are: cu: 38.26%, Mn: 25.83%, Zn: 16.26%, Al: 15.80%, Ag: 2.31%, Ru: 1.54 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) 12.0g of Cu (NO)₃)₂·3H₂O、6g Mn(NO₃)₂And 4g Zn (NO)₃)₂·6H₂O in 200ml H₂Preparing a metal ion mixed solution by using O; 18g of Na₂CO₃Dissolved in 200ml of H₂Preparing a precipitant solution from O;

(2) in a water bath at 80 ℃, dropwise adding a metal ion mixed solution and a precipitant solution in a cocurrent flow manner to perform coprecipitation reaction, stirring while dropwise adding, keeping the pH value of a precipitation system at 7.2, stirring at a constant temperature for 120min after dropwise adding is finished, and then washing with clear water to remove impurity ions to obtain a Cu-Mn-Zn-O precipitate;

(3) to the precipitate in the step (2) was added 1.6g of Al (OH)₃、0.5g AgNO₃、0.4g RuCl₃Obtaining a blend, then adding 300ml of deionized water into the blend, heating to 80 ℃, and stirring for 60 min;

(4) and (4) carrying out suction filtration on the blend in the step (3), carrying out solid-liquid separation, drying the obtained filter cake at 120 ℃ for 12h, heating to 400 ℃ in a muffle furnace, and roasting for 10h to obtain the catalyst 4 containing Ag2.31% and Ru1.54%.

Example 5

The embodiment prepares a dimethyl maleate hydrogenation catalyst containing elements of Cu, Mn, Al, Zn, Ag, and Ru, wherein the mole percentages of the elements are: cu: 38.26%, Mn: 25.83%, Zn: 16.26%, Al: 15.80%, Ag: 2.31%, Ru: 1.54 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst is generally the same as that in the embodiment 4, except that in the step (2), 100g of hydrogen peroxide with the mass fraction of 28% is added as a pore-expanding agent during the concurrent dripping coprecipitation reaction of the metal ion mixed solution and the precipitant solution, and finally the catalyst 5 is obtained.

The hydrogen peroxide pore-expanding agent used in the embodiment can change the pores of the catalyst, so that the service life of the catalyst can be prolonged, pores can be formed between the pores of the catalyst by hydrogen peroxide in a physical mode, the stability of the catalyst is improved, and meanwhile, the hydrogen peroxide pore-expanding agent is more beneficial to energy conservation and environmental protection.

Test of catalyst Performance

In order to verify the activity of the prepared catalyst, the catalyst is used for preparing 1, 4-butanediol by catalytic hydrogenation of dimethyl maleate, and the test process is carried out by adopting a fixed bed reactor. The specific method comprises the following steps:

a. activating the catalyst: granulating the roasted catalyst powder to 40-60 meshes, loading 10g of catalyst into a reaction tube of a fixed bed reactor, and carrying out N-pass treatment₂Diluted H₂The mixed gas (the hydrogen content is 40-60%) is heated to 230 ℃ in a programmed manner to reduce and activate the catalyst until the hydrogen concentration of the gas inlet and the gas outlet is consistent;

b. carrying out dimethyl maleate catalytic hydrogenation by using the activated catalyst: pressurizing and heating in a reaction tube, wherein the pressure is 3-5 MPa, preferably 4MPa, the temperature is 170-200 ℃, preferably 180 ℃, the liquid space velocity is 0.2 g/g, and the molar ratio of hydrogen to ester is 200: 1. Then, the raw material dimethyl maleate is pumped into a reaction tube through an advection pump, the feeding rate is 2g/h, and the reaction product is condensed and collected to analyze the composition by gas chromatography.

Table 1 below shows the results of the catalysts prepared herein for the hydrogenation of dimethyl maleate, in which BDO is 1, 4-butanediol, GBL is gamma-butyrolactone, and THF is tetrahydrofuran in Table 1. The units for each product value in tables 1, 2, and 3 are in mole percent (mol%), wherein BDO is 1, 4-butanediol, GBL is gamma-butyrolactone, THF is tetrahydrofuran, and DMS is dimethyl succinate.

TABLE 1

It was confirmed from the above experiment that in the catalytic reaction using the catalyst containing no Ag or Ru (catalyst 1), the reaction was not completely converted, and the BDO + GBL content in the product was low. In the catalytic reaction carried out by using the catalyst (catalyst 2) added with Ag and the catalyst (catalyst 3) added with Ru respectively, the content of BDO + GBL in the product is improved to some extent, so the optimal efficiency of the catalytic reaction can be realized by adding Ag and Ru simultaneously, the catalytic reaction can be close to complete conversion, and the content of BDO + GBL reaches 93.4 percent.

In the catalytic reaction carried out by adding hydrogen peroxide as a pore-expanding agent to obtain the catalyst 5, although the content of BDO + GBL in the product is increased compared with that of the catalysts 1-3, the THF content in the product is increased, and the purpose of initially reducing the byproduct THF (tetrahydrofuran) cannot be achieved. In conclusion, based on the above data, catalyst 4, i.e., a catalyst having the element Cu-Mn-Al-Zn-Ag-Ru-O, was optimally selected.

Secondly, in order to find the optimal molar content of each element in the catalyst, the invention adjusts the content of Ag and Ru in the catalyst on the basis of the catalyst 4, and obtains an example 6 and an example 7:

example 6

The embodiment prepares a dimethyl maleate hydrogenation catalyst containing elements of Cu, Mn, Al, Zn, Ag, and Ru, wherein the mole percentages of the elements are: cu: 39.12%, Mn: 26.41%, Zn: 16.63%, Al: 16.16%, Ag: 0.93%, Ru: 0.76 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) 12g of Cu (NO)₃)₂·3H₂O、6g Mn(NO₃)₂And 4g Zn (NO)₃)₂·6H₂O in 200ml H₂Preparing a metal ion mixed solution by using O; 18g of Na₂CO₃Dissolved in 200ml of H₂Preparing a precipitant solution from O;

(2) in a water bath at 80 ℃, dropwise adding a metal ion mixed solution and a precipitant solution in a cocurrent flow manner to perform coprecipitation reaction, stirring while dropwise adding, keeping the pH value of a precipitation system at 7.2, stirring at a constant temperature for 120min after dropwise adding is finished, and then washing with clear water to remove impurity ions to obtain a Cu-Mn-Zn-O precipitate;

(3) to the precipitate in the step (2) was added 1.6g of Al (OH)₃、0.2g AgNO₃、0.2g RuCl₃Obtaining a blend, then adding 300ml of deionized water into the blend, heating to 80 ℃, and stirring for 60 min;

(4) and (4) carrying out suction filtration on the blend in the step (3), carrying out solid-liquid separation, drying the obtained filter cake at 120 ℃ for 12h, heating to 400 ℃ in a muffle furnace, and roasting for 10h to obtain the catalyst 6 containing 2.31% of Ag and 1.54% of Ru.

Example 7

The embodiment prepares a dimethyl maleate hydrogenation catalyst containing elements of Cu, Mn, Al, Zn, Ag, and Ru, wherein the mole percentages of the elements are: cu: 37.17%, Mn: 25.09%, Zn: 15.81%, Al: 15.35%, Ag: 4.41%, Ru: 2.17 percent.

The preparation method of the dimethyl maleate hydrogenation catalyst comprises the following steps:

(1) 12.0g of Cu (NO)₃)₂·3H₂O、6g Mn(NO₃)₂And 4g Zn (NO)₃)₂·6H₂O in 200ml H₂Preparing a metal ion mixed solution by using O; 18g of Na₂CO₃Dissolved in 200ml of H₂Preparing a precipitant solution from O;

(2) in a water bath at 80 ℃, dropwise adding a metal ion mixed solution and a precipitant solution in a cocurrent flow manner to perform coprecipitation reaction, stirring while dropwise adding, keeping the pH value of a precipitation system at 7.2, stirring at a constant temperature for 120min after dropwise adding is finished, and then washing with clear water to remove impurity ions to obtain a Cu-Mn-Zn-O precipitate;

(3) to the precipitate in the step (2) was added 1.6g of Al (OH)₃、1g AgNO₃、0.6g RuCl₃Obtaining a blend, then adding 300ml of deionized water into the blend, heating to 80 ℃, and stirring for 60 min;

(4) and (4) carrying out suction filtration on the blend in the step (3), carrying out solid-liquid separation, drying the obtained filter cake at 120 ℃ for 12h, heating to 400 ℃ in a muffle furnace, and roasting for 10h to obtain the catalyst 7 containing 2.31% of Ag and 1.54% of Ru.

The method in test (one) is adopted to catalyze the hydrogenation of dimethyl maleate to prepare 1, 4-butanediol, and the catalytic activities of the obtained catalyst 6 and the obtained catalyst 7 are compared with that of the obtained catalyst 4, so that the following results are obtained as shown in the following table 2:

TABLE 2

As can be seen from the data in Table 2, catalyst 6 (when the Ag and Ru content is low) has a conversion of 99% and cannot be completely converted, and catalyst 7 (when the Ag and Ru content is high) has a high THF content and affects the conversion of BDO + GBL, although the BDO and GBL products obtained in example 7 have a smaller difference from example 4 and the Ag and Ru content in the raw material of catalyst 7 is higher, catalyst 4 is selected as the most preferable from the viewpoint of cost reduction.

And thirdly, in order to verify the catalytic activity of the catalyst 4 at different temperatures, the method of the first test is adopted to prepare the 1, 4-butanediol by catalyzing the dimethyl maleate to be hydrogenated by the catalyst 4. And the catalyst 4 was evaluated for its activity at different temperatures, which were respectively 170 ℃, 180 ℃, 190 ℃, 200 ℃, and the other reaction conditions were the same as those of the test (one), and the results obtained are shown in table 3 below:

TABLE 3

From Table 3, it can be seen that the THF reaction product amount is gradually increased with the increase of the reaction temperature, and the reaction temperature should be decreased as much as possible in order to minimize the THF production rate, but when the temperature is 170 ℃, the conversion rate of dimethyl maleate is less than 100%, and the conversion rate is not complete, and the other products cannot be improved as a whole, so 180 ℃ is selected as the optimum temperature.

Example 8

(IV) to verify the stability of catalyst 4, we evaluated it for lifetime.

The catalyst evaluation method in test (one) was employed using catalyst 4. Reaction conditions are as follows: the pressure is 4MPa, the temperature is 180 ℃, the liquid space velocity is 0.3g/g, and the hydrogen-ester molar ratio is 200: 1. The reaction result is: the initial conversion of dimethyl maleate was 100%, the BDO selectivity was 89.6%, the GBL selectivity was 3.8%, and the THF selectivity was 3.9%; after the continuous operation for 2000h, the conversion rate of the maleic acid dimethyl ester can still reach 99.5%, the BDO selectivity is 80.6%, the GBL selectivity is 9.8%, and the THF selectivity is 6.4%.

Finally, it should be noted that: the above embodiments are merely illustrative and not restrictive of the technical solutions of the present invention, and any equivalent substitutions and modifications or partial substitutions made without departing from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.