阅读说明：本技术 一种碳酸二甲酯的生产工艺 (Production process of dimethyl carbonate ) 是由 许可 尹训娟 张新平 水清洋 卢健行 刘守国 于 2020-12-29 设计创作，主要内容包括：本发明涉及一种碳酸二甲酯的生产工艺,所述方法包括：(1)将甲醇和多孔催化剂置于反应容器中后将容器封闭,吹扫排出容器中的空后通入二氧化碳并加热；所述多孔催化剂的制备方法包括：(a)将氢氧化铜粉末和氢氧化镍粉末溶于氨水中,搅拌均匀,形成双金属络合物溶液；(b)将多孔蒙脱石浸入双金属络合物溶液中,然后在保护气氛中对混合物进行烧结并蒸干,得催化剂前驱体；(c)将催化剂前驱体在还原性气氛进行加热,即得。(2)反应结束后先将反应容器降温至室温,在排出容器中气体后放出反应物,分离出其中碳酸二甲酯,即得。本发明的方法将铜和镍负载在具有多孔结构的蒙脱石上,有效增加了相同质量的载体上催化剂的含量,促进了催化效率。(The invention relates to a production process of dimethyl carbonate, which comprises the following steps: (1) placing methanol and a porous catalyst in a reaction container, sealing the container, blowing and discharging the air in the container, introducing carbon dioxide, and heating; the preparation method of the porous catalyst comprises the following steps: (a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water, and uniformly stirring to form a bimetallic complex solution; (b) immersing porous montmorillonite into a bimetallic complex solution, sintering the mixture in a protective atmosphere, and evaporating to dryness to obtain a catalyst precursor; (c) and heating the catalyst precursor in a reducing atmosphere to obtain the catalyst. (2) After the reaction is finished, the temperature of the reaction container is firstly reduced to room temperature, reactants are discharged after the gas in the container is discharged, and the dimethyl carbonate is separated out, thus obtaining the product. According to the method, copper and nickel are loaded on the montmorillonite with the porous structure, so that the content of the catalyst on the carrier with the same quality is effectively increased, and the catalytic efficiency is promoted.)

1. The production process of the dimethyl carbonate is characterized by comprising the following steps:

(1) placing methanol and a porous catalyst in a reaction container, sealing the container, introducing carbon dioxide to purge and exhaust air in the container, continuously introducing the carbon dioxide to pressurize the container to a set pressure after the purging is finished, and then heating and reacting the container;

(2) after the reaction is finished, cooling the reaction container to room temperature, discharging the gas in the container, then discharging the reactant, and separating the dimethyl carbonate in the reactant to obtain the product;

the preparation method of the porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water, and uniformly stirring to form a bimetallic complex solution for later use;

(b) completely immersing porous montmorillonite into the bimetallic complex solution, then evaporating liquid components in the mixture to dryness in a protective atmosphere, and continuing heating and decomposing to obtain a catalyst precursor for later use;

(c) and (3) placing the catalyst precursor in a reducing atmosphere to carry out heating reduction reaction to obtain the catalyst.

2. The process for producing dimethyl carbonate according to claim 1, wherein in the step (1), the ratio of methanol to the catalyst is 90-130 ml: 0.9 to 1.8 g.

3. The process for producing dimethyl carbonate according to claim 1, wherein in the step (1), the pressure is 1.2 to 4.5MPa, the heating temperature is 105 to 140 ℃, and the reaction time is kept above 3 h.

4. The process for producing dimethyl carbonate according to claim 1, wherein in the step (a), the mass ratio of the copper hydroxide powder to the nickel hydroxide powder is 1:0.5 to 0.9.

5. The process for producing dimethyl carbonate according to claim 1, wherein in the step (a), the mass concentration of the ammonia water is 25-28%.

6. The process for producing dimethyl carbonate according to claim 1, wherein in the step (b), the total mass ratio of the porous montmorillonite to the copper hydroxide powder and the nickel hydroxide powder in the step (b) is 65 to 85: 15-35; preferably, in step (b), the protective atmosphere includes any one of nitrogen and argon.

7. The dimethyl carbonate production process according to claim 1, wherein in the step (b), the heating temperature is 80-95 ℃, and the heating time is more than 0.5h after the liquid components are evaporated to dryness.

8. The process for producing dimethyl carbonate according to claim 1, wherein in the step (c), the reducing atmosphere comprises any one of hydrogen and carbon monoxide.

9. The process for producing dimethyl carbonate according to claim 1, wherein in the step (c), the heating temperature is 450-550 ℃, the heating time is 0.5-1.5 h, and preferably, the heating temperature is not lower than 480 ℃.

10. The process for producing dimethyl carbonate according to any one of claims 1 to 9, wherein in the step (2), the dimethyl carbonate product in the reaction product is separated by rectification.

Technical Field

The invention relates to the field of dimethyl carbonate preparation, in particular to a production process of dimethyl carbonate.

Background

Dimethyl carbonate (C)₃H₆O₃) The dimethyl carbonate is an important organic synthesis intermediate, and has a molecular structure simultaneously with functional groups such as methyl, methoxy, carbonyl and the like, so that the dimethyl carbonate has various reaction performances, such as application in methylating agents, carbonylating agents and the like. At present, dimethyl carbonate is widely used as a solvent in the industries of paint, coating and adhesive. The synthesis method of the dimethyl carbonate mainly comprises the following steps: phosgene processes, oxidative carbonylation reactions using copper chloride or nitric oxide as catalysts, transesterification of propylene carbonate with methanol, urea methanolysis reactions, all suffer from various disadvantages, for example, the toxicity and corrosiveness of phosgene, which have long led to the failure of such processes. With CuCl₂The method for preparing the dimethyl carbonate by catalyzing the oxidative carbonylation of the methanol by the catalyst has low conversion per pass and serious catalyst deactivation. The method for preparing the dimethyl carbonate by the urea methanolysis reaction has higher production cost. At present, the synthesis of dimethyl carbonate by using carbon dioxide and methanol has been a research hotspot, which can effectively utilize greenhouse gas carbon dioxide, but the method is difficult to be carried out under conventional conditions and needs a catalyst for catalysis.

Disclosure of Invention

Therefore, the invention provides a production process of dimethyl carbonate, and the preparation method loads copper and nickel on montmorillonite with a porous structure, effectively increases the content of a catalyst on a carrier with the same quality, and promotes the catalytic efficiency. In order to achieve the purpose, the invention discloses the following technical scheme:

a production process of dimethyl carbonate comprises the following steps:

(1) placing methanol and a porous catalyst in a reaction container, sealing the container, introducing carbon dioxide to purge and exhaust air in the container, continuously introducing the carbon dioxide to pressurize the container to a set pressure after the purging is finished, and heating the container; the preparation method of the porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water, and uniformly stirring to form a bimetallic complex solution for later use;

(b) completely immersing porous montmorillonite into the bimetallic complex solution, then evaporating liquid components in the mixture to dryness in a protective atmosphere, and continuing heating and decomposing to obtain a catalyst precursor for later use;

(c) and (3) placing the catalyst precursor in a reducing atmosphere to carry out heating reduction reaction, thus obtaining the porous catalyst.

(2) After the reaction is finished, the temperature of the reaction container is firstly reduced to room temperature, the reactant is discharged after the gas in the container is discharged, and the dimethyl carbonate in the reactant is separated out, thus obtaining the product.

Further, in the step (1), the ratio of the methanol to the catalyst is 90-130 ml: 0.9 to 1.8 g.

Further, in the step (1), the pressure is 1.2-4.5 MPa, the heating temperature is 105-140 ℃, and the reaction time is kept above 3h, so that the reaction is fully carried out.

Further, in the step (a), the mass ratio of the copper hydroxide powder to the nickel hydroxide powder is 1: 0.5-0.9, and copper and nickel have good synergistic effect in catalyzing carbon dioxide and methanol to synthesize dimethyl carbonate.

Further, in the step (a), the mass concentration of the ammonia water is 25-28%. In the invention, the ammonia water not only plays an important role as a medium, and is convenient for dissolving and loading the copper hydroxide and the nickel hydroxide in the porous montmorillonite. In addition, ammonia water also has the effect of further activating the porous montmorillonite in the subsequent soaking process.

Further, in the step (b), the total mass ratio of the porous montmorillonite to the copper hydroxide powder and the nickel hydroxide powder is 65-85: 15 to 35.

Further, in the step (b), the protective atmosphere includes any one of nitrogen, argon, and the like.

Further, in the step (b), the heating temperature is 80-95 ℃, the heating time is that the liquid components are evaporated to dryness, and then the heat preservation is continued for more than 0.5 h. The bimetallic complex is gradually attached to the surface of the porous montmorillonite and the inner wall of each pore channel in the porous montmorillonite by heating, and the bimetallic complex is decomposed into oxides.

Further, in the step (c), the reducing atmosphere comprises hydrogen or carbon monoxide, etc., and the main function of the reducing atmosphere is to reduce copper and nickel oxides to form the Cu-Ni double alloy catalyst.

Further, in the step (c), the heating temperature is 450-550 ℃, preferably 480 ℃ or more, and the heating time is 0.5-1.5 h. Besides ensuring that oxides of copper and nickel can be fully reduced at high temperature, the copper-nickel composite material can play a sintering role, so that the obtained copper and nickel are firmly attached to the porous montmorillonite.

Further, in the step (2), a dimethyl carbonate product in the reaction product is separated by adopting a method such as rectification and the like.

Compared with the prior art, the invention has the following beneficial effects:

(1) because both the copper hydroxide and the nickel hydroxide are insoluble or insoluble in water and can not be directly loaded in each pore channel in the porous montmorillonite, the invention adopts ammonia water to dissolve the two hydroxides to form a soluble bimetallic complex which can fully permeate into each pore channel in the porous montmorillonite along with the solute, thereby effectively realizing the loading of copper and nickel elements in each pore channel of the porous montmorillonite.

(2) According to the invention, the method of first mixing and dissolving copper hydroxide and nickel hydroxide, then carrying and decomposing, and finally reducing and sintering is adopted, the Cu-Ni bimetallic catalyst with a synergistic catalytic effect is carried on the surface of the montmorillonite with the porous structure and each pore channel in the montmorillonite, and as the porous montmorillonite has a rich three-dimensional pore channel structure, more catalysts can be carried on the surface of the montmorillonite, so that the loading amount of the catalysts on the carrier with the same mass is increased, and the catalytic efficiency of the catalysts is improved.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. The invention will now be further illustrated by means of specific embodiments.

Example 1

1. A preparation method of a porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water (mass concentration of 28%) according to the mass ratio of 2:1, and stirring until the powder substances are completely dissolved to obtain a bimetallic complex solution for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 35:65, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 90 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 40min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 480 ℃, and preserving the heat for 1.5h to carry out reduction reaction, thereby obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in 100 ml: placing 1.8g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 2MPa after the air is completely purged, and then heating the container to 120 ℃;

(2) after reacting for 4 hours, firstly cooling the reaction kettle to room temperature, then discharging gas in the reaction kettle, then discharging reactants, and separating dimethyl carbonate in the reactants to obtain the product.

Example 2

1. A preparation method of a porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water (mass concentration of 28%) according to the mass ratio of 1:0.8, and stirring until the powder substances are completely dissolved to obtain a bimetallic complex solution for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 30:70, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 95 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 30min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 450 ℃ and preserving the heat for 1.5h to carry out reduction reaction, thus obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in a 120 ml: placing 1.5g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 3.5MPa after the air is completely purged, and then heating the container to 105 ℃;

(2) after reacting for 3.5h, firstly cooling the reaction kettle to room temperature, then discharging the gas in the reaction kettle, then discharging the reactant, and separating out the dimethyl carbonate in the reactant to obtain the product.

Example 3

1. A preparation method of a porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water (mass concentration is 25%) according to the mass ratio of 1:0.9, and stirring until the powder substances are completely dissolved to obtain a bimetallic complex solution for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 20:80, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 90 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 50min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 520 ℃ and preserving the temperature for 1.5h to carry out reduction reaction, thus obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in a volume of 90 ml: placing 0.9g of the mixture into a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 4.5MPa after the air is completely discharged, and then heating the container to 130 ℃;

(2) after reacting for 3.0h, firstly cooling the reaction kettle to room temperature, then discharging the gas in the reaction kettle, then discharging the reactant, and separating out the dimethyl carbonate in the reactant to obtain the product.

Example 4

1. A preparation method of a porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder and nickel hydroxide powder in ammonia water (mass concentration is 25%) according to the mass ratio of 1:0.6, and stirring until the powder substances are completely dissolved to obtain a bimetallic complex solution for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 15:85, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 80 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 65min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 550 ℃, and preserving heat for 0.5h to carry out reduction reaction, thereby obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in 130 ml: placing 1.8g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 1.2MPa after the air is completely purged, and then heating the container to 140 ℃;

(2) after reacting for 3.0h, firstly cooling the reaction kettle to room temperature, then discharging the gas in the reaction kettle, then discharging the reactant, and separating out the dimethyl carbonate in the reactant to obtain the product.

Test example 1

1. A preparation method of a porous catalyst comprises the following steps:

(a) dissolving copper hydroxide powder in ammonia water (mass concentration of 28%), and stirring until the powder is completely dissolved to obtain a bimetallic complex solution for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 35:65, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 90 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 40min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 480 ℃, and preserving the heat for 1.5h to carry out reduction reaction, thereby obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in 100 ml: placing 1.8g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 2MPa after the air is completely purged, and then heating the container to 120 ℃;

(2) after reacting for 4 hours, firstly cooling the reaction kettle to room temperature, then discharging gas in the reaction kettle, then discharging reactants, and separating dimethyl carbonate in the reactants to obtain the product.

Test example 2

1. A preparation method of a porous catalyst comprises the following steps:

(a) dissolving nickel hydroxide powder in ammonia water (mass concentration of 28%), and stirring until the powder is completely dissolved to obtain a bimetallic complex solution for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 35:65, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 90 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 40min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 480 ℃, and preserving the heat for 1.5h to carry out reduction reaction, thereby obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in 100 ml: placing 1.8g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 2MPa after the air is completely purged, and then heating the container to 120 ℃;

(2) after reacting for 4 hours, firstly cooling the reaction kettle to room temperature, then discharging gas in the reaction kettle, then discharging reactants, and separating dimethyl carbonate in the reactants to obtain the product.

Test example 3

1. A preparation method of a porous catalyst comprises the following steps:

(a) mixing copper hydroxide powder and nickel hydroxide powder with water according to the mass ratio of 2:1, and stirring to form suspension for later use.

(b) According to the total mass of the copper hydroxide powder and the nickel hydroxide powder: weighing the porous montmorillonite according to the mass ratio of 35:65, completely soaking the porous montmorillonite into the bimetallic complex solution obtained in the step (a) in the embodiment, heating the mixture in a nitrogen atmosphere (at the temperature of 90 ℃) until liquid components in the mixture are evaporated to dryness, and continuing to preserve heat for 40min to obtain a catalyst precursor for later use.

(c) Putting the catalyst precursor obtained in the step (b) into H₂And then heating to 480 ℃, and preserving the heat for 1.5h to carry out reduction reaction, thereby obtaining the porous catalyst.

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and the porous catalyst prepared in this example were mixed in 100 ml: placing 1.8g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 2MPa after the air is completely purged, and then heating the container to 120 ℃;

(2) after reacting for 4 hours, firstly cooling the reaction kettle to room temperature, then discharging gas in the reaction kettle, then discharging reactants, and separating dimethyl carbonate in the reactants to obtain the product.

Test example 4

2. A production process of dimethyl carbonate comprises the following steps:

(1) methanol and a catalyst (the mass ratio of metallic copper to nickel is 2:1) are mixed according to the weight ratio of 100 ml: placing 1.8g of the mixture in a high-pressure reaction kettle, then introducing carbon dioxide to purge and discharge air in the reaction kettle, continuously introducing the carbon dioxide to pressurize the reaction kettle to 2MPa after the air is completely purged, and then heating the container to 120 ℃;

(2) after reacting for 4 hours, firstly cooling the reaction kettle to room temperature, then discharging gas in the reaction kettle, then discharging reactants, and separating dimethyl carbonate in the reactants to obtain the product.

The conversion of methanol and the selectivity to dimethyl carbonate in the above examples and test examples were calculated, and the results are shown in tables 1 and 2, respectively.

TABLE 1

	Example 1	Example 2	Example 3	Example 4
					Conversion of methanol/%)	18.2	16.7	15.9	16.1
Selectivity of dimethyl carbonate/%)	99.4	99.1	98.5	98.7

TABLE 2

	Test example 1	Test example 2	Test example 3	Test examples4
					Conversion of methanol/%)	8.3	11.4	1.6	5.2
Selectivity of dimethyl carbonate/%)	76.9	81.8	5.7	66.5

As can be seen from the results in table 1, compared with the test examples, the catalysts in examples 1 to 4 have significantly improved two indexes of conversion rate of methanol and selectivity of dimethyl carbonate, and since the catalysts prepared in test examples 1 and 2 do not have the property of Cu — Ni bimetal, the two catalysts do not have synergistic catalytic effect, so that the respective catalytic effect on the reaction of methanol and carbon dioxide is small, but since the two catalysts have the porous characteristic of porous montmorillonite, the content of the catalytic active component on the carrier per unit mass is effectively increased, and the catalytic efficiency is improved, so that the two indexes in test examples 1 and 2 are still significantly better than those in test example 4. However, the copper hydroxide and nickel hydroxide in test example 3 were difficult to dissolve in water in large amounts, which not only resulted in the failure to enter the channels in the porous montmorillonite but also resulted in the easy clogging of the channels, resulting in a lower content of catalytically active components per unit mass of the carrier of the catalyst obtained in test example 3, and a lower catalytic efficiency.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.