CN110028483A - A kind of method that outer circulation atomizing gas-liquid contact technique prepares cyclic carbonate - Google Patents

Abstract

The invention belongs to the technical field of cyclic carbonate preparation, and relates to a method for preparing cyclic carbonate by an external circulation spray type gas-liquid contact process. The invention adopts the external circulation spray gas-liquid contact process, uses the aluminum complex containing quaternary ammonium salt in the molecule as a bifunctional catalyst, and under the reaction pressure of 0.3-3.0 MPa and the reaction temperature of 60-150 DEG C, carbon dioxide and alkylene oxide are mixed. Coupling reaction as raw material for the efficient preparation of cyclic carbonate. The invention solves the defect of the prior art that after the conversion rate of alkylene oxide reaches a certain level, the reaction rate shows a sharp decline. The benefit of the invention is to improve the efficiency of coupling carbon dioxide and alkylene oxide to prepare cyclic carbonate, and has good industrial application value.

Description

A kind of method for preparing cyclic carbonate by external circulation spray type gas-liquid contact process

technical field

The invention belongs to the technical field of cyclic carbonate preparation, and relates to a method for preparing cyclic carbonate by an external circulation spray type gas-liquid contact process, which is a method for preparing cyclic carbonate by coupling reaction of alkylene oxide and carbon dioxide.

Background technique

Carbon dioxide (CO ₂ ), as an important carbon source on the earth, can be converted into carbohydrates through photosynthesis, and oxygen is released at the same time, which is one of the most important reactions to maintain ecological cycles. However, the excessive emission of CO ₂ in human daily life and industrial production has disrupted the "balance of payments" in nature, making CO ₂ the main gas that causes the greenhouse effect. Therefore, the abatement and chemical or physical fixation of _CO2 has become one of the most important strategic research topics worldwide. Under the action of catalyst, carbon dioxide can react with alkylene oxide to prepare cyclic carbonate. As high-boiling, high-polarity organic solvents with excellent properties, these cyclic carbonates are widely used in organic synthesis, cosmetic industry, gas separation, battery electrolyte and metal extraction.

At present, there are many patent reports at home and abroad on the preparation of cyclic carbonate by coupling carbon dioxide and alkylene oxide. For example, in US 4314945, McMullen used tetrahydrocarbyl quaternary ammonium salt to catalyze the reaction of alkylene oxide with carbon dioxide to synthesize cyclic carbonate; in US 4786741 and US 4841072, Sachs and Harvey used quaternary phosphonium salt catalysts respectively under the pressure of 2.5-20MPa , realized the cycloaddition reaction of carbon dioxide and ethylene oxide, and prepared the corresponding cyclic carbonate; in US 4931571, Weinstein used quaternary arsine halide as a catalyst to catalyze carbon dioxide and ethylene oxide at 90 ~ 200 ℃ alkane reaction to synthesize ethylene carbonate. Some domestic experts have also made some breakthroughs in this field. For example, in CN1343668, Deng Youquan used ionic liquid and alkali metal halide or tetrabutylammonium bromide to form a binary catalytic system. At 1.5-4.5MPa, the epoxy compound was successfully converted into the corresponding cyclic carbonate; in CN 101003531, He Liangnian used polyethylene glycol functionalized with quaternary ammonium salt or quaternary phosphonium salt as a catalyst to realize carbon dioxide. The corresponding cyclic carbonates were synthesized by coupling reaction with alkylene oxides. The advantage of the catalyst is that it is easy to recover and recycle, and is suitable for continuous production; in CN 101972674, Liu Binyuan synthesized a simple tetradentate Schiff base aluminum complex containing quaternary ammonium salt in the molecule, and the catalyst is used for catalysis In the coupling reaction of carbon dioxide and alkylene oxide, the catalytic efficiency can reach up to 3750 mol cyclic carbonate/mol catalyst. In recent years, we have also used tetradentate Schiff base aluminum complexes as catalysts. Under the synergistic effect of quaternary ammonium salts or quaternary phosphonium salts, we have realized the coupling reaction of carbon dioxide and alkylene oxide, and synthesized the corresponding cyclic carbonate ( CN 1416953, CN 1415416 and CN 1544431).

In the methods for preparing cyclic carbonates reported above, traditional still-type or shell-and-tube reaction processes have been adopted. In these processes, when the conversion of alkylene oxide reaches a certain level, the reaction rate shows a sharp drop, resulting in a long time required to achieve almost complete conversion of alkylene oxide. Therefore, the reaction process of the kettle type or the tubular type has low efficiency and high energy consumption.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a method for enhancing gas-liquid mass transfer through an external circulation spray reaction process, and efficiently realizing the coupling reaction of carbon dioxide and alkylene oxide to synthesize cyclic carbonate.

Technical scheme of the present invention:

A method for preparing cyclic carbonate by an external circulation spray type gas-liquid contact process adopts an external circulation spray reactor, uses a bifunctional catalyst as a catalyst, and under the reaction pressure of 0.3-3.0 MPa and the reaction temperature of 60-150 DEG C, Carbon dioxide and alkylene oxide are used as raw materials for coupling reaction to prepare cyclic carbonate.

The reaction process is as follows: adding a cyclic carbonate containing a catalyst into the external circulation spray reactor, heating the starting material to the reaction temperature through a heat exchanger, feeding carbon dioxide to the reaction system pressure to be the reaction pressure; and then circulating the external spray reactor Introduce alkylene oxide and carbon dioxide into the medium, and maintain the reaction pressure; after the feeding is completed, continue to react until all the alkylene oxide is consumed, then transfer the reaction material in the external circulation spray reactor to the flash tank, discharge carbon dioxide, reduce Press distillation to obtain cyclic carbonate, and the residual liquid containing the catalyst is recycled as the starting material of the next batch of reaction.

The mass ratio of the alkylene oxide to the catalyst is 50:1 to 10000:1.

The molar ratio of the alkylene oxide to carbon dioxide is 1:1.

The catalyst is a tetradentate Schiff base aluminum complex, and the molecule contains one or more quaternary ammonium salt or quaternary phosphonium salt groups, and its structure is:

where:

Indicates the connection position;

R ₂ =H, CH ₃ , CH ₂ CH ₃ or Ph;

R ₃ =C ₁ -C ₆ alkyl or phenyl;

X=F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , CH ₃ COO ^- , CCl ₃ COO ^- , CF ₃ COO ^- , ClO ₄ ^- , BF ₄ ^- , BPh ₄ ^- , N ₃ ^- , right Toluic acid, p-toluenesulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2,4-dinitrophenol oxygen, 3,5-dinitro oxyphenol, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, 3,5-difluorophenoloxy, 3,5-di-trifluoromethylphenoloxy, or pentafluorophenol Oxygen anion;

n=1-5.

The alkylene oxide is ethylene oxide or propylene oxide.

Beneficial effects of the present invention:

The invention adopts the external circulation spray reaction process to prepare the cyclic carbonate, which can effectively strengthen the gas-liquid, improve the reaction efficiency, and has a high conversion rate, and solves the problem that in the prior art, when the conversion rate of alkylene oxide reaches a certain level, the reaction rate shows a sharp drop. Defects, has good industrial application value.

Description of drawings

Fig. 1 is the process flow diagram of the external circulation spray type gas-liquid contact catalysis to prepare cyclic carbonate.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

The process flow of the external circulation spray type gas-liquid contact catalytic preparation of cyclic carbonate of the present invention is shown in Figure 1, and the main reactor is an external circulation spray reactor.

Example 1:

An external circulation spray reactor with an effective volume of 10 L was charged with 0.08 g of bifunctional catalyst (X is bromide anion; R ₁ =C ₂ H ₄ ; R ₂ =H; R ₃ =n-butyl; n=3) 2.0Kg ethylene carbonate. The reaction device was started, and the starting material was heated to 150° C. through a heat exchanger, and carbon dioxide was introduced into the reaction system until the pressure was 3.0 MPa. 4.0Kg of ethylene oxide and 4.0Kg of carbon dioxide (equimolar amount) were continuously added within 5 hours. During the feeding process, the feeding amounts of alkylene oxide and carbon dioxide should be kept the same, and the system pressure should be maintained at 3.0MPa. After the addition was completed, the reaction was continued for 5 minutes. The reaction material was transferred to a flash tank, and after carbon dioxide was discharged, about 8.0Kg of ethylene carbonate (selectivity>99.5%) was obtained by distillation under reduced pressure, and the catalyst-containing residue was used as the starting material for recycling.

Example 2:

2.0 g of bifunctional catalyst (X is chloride anion; R ₁ =C ₂ H ₄ ; R ₂ =H; R ₃ =n-butyl; n=3) was added to an external circulation spray reactor with an effective volume of 10 L. Kg ethylene carbonate. The reaction device was started, and the starting material was heated to 120° C. through a heat exchanger, and carbon dioxide was introduced into the reaction system until the pressure was 0.6 MPa. 4.0Kg of ethylene oxide and 4.0Kg of carbon dioxide (equimolar amount) were continuously added within 5 hours. During the feeding process, the feeding amounts of alkylene oxide and carbon dioxide should be kept the same, and the system pressure should be maintained at 0.6MPa. After the addition was completed, the reaction was continued for 10 minutes. The reaction material was transferred to a flash tank, and after carbon dioxide was discharged, about 8.0Kg of ethylene carbonate (selectivity>99.5%) was obtained by distillation under reduced pressure, and the catalyst-containing residue was used as the starting material for recycling.

Example 3:

2.0 g of bifunctional catalyst (X is chloride anion; R ₁ =C ₆ H ₄ ; R ₂ =CH ₃ ; R ₃ =ethyl; n=2) was charged into an external circulation spray reactor with an effective volume of 10 L. Kg propylene carbonate. The reaction device was started, and the starting material was heated to 120° C. through a heat exchanger, and carbon dioxide was introduced into the reaction system until the pressure was 0.6 MPa. 4.55Kg of propylene oxide and 3.45Kg of carbon dioxide (equimolar amount) were continuously added within 5 hours. During the feeding process, the feeding amounts of alkylene oxide and carbon dioxide should be kept the same, and the system pressure should be maintained at 0.6MPa. After the addition was completed, the reaction was continued for 20 minutes. The reaction material was transferred to a flash tank, and after carbon dioxide was discharged, about 8Kg of propylene carbonate (selectivity>99.5%) was obtained by distillation under reduced pressure, and the residual liquid containing the catalyst was recycled as the starting material.

Example 4:

2.0 g of bifunctional catalyst (X is chloride anion; R ₁ =C ₆ H ₄ ; R ₂ =CH ₃ ; R ₃ =ethyl; n=2) was added to an external circulation spray reactor with an effective volume of 10 L. Kg propylene carbonate. The reaction device was started, and the starting material was heated to 60° C. through a heat exchanger, and carbon dioxide was introduced into the reaction system until the pressure was 0.3 MPa. 4.55Kg of propylene oxide and 3.45Kg of carbon dioxide (equimolar amount) were continuously added within 8 hours. During the feeding process, the feeding amounts of alkylene oxide and carbon dioxide should be kept the same, and the system pressure should be maintained at 0.3MPa. After the addition was completed, the reaction was continued for 50 minutes. The reaction material was transferred to a flash tank, and after carbon dioxide was discharged, about 8Kg of propylene carbonate (selectivity>99.5%) was obtained by distillation under reduced pressure, and the residual liquid containing the catalyst was recycled as the starting material.

Example 5:

2.0Kg containing 30g bifunctional catalyst (X is chloride anion; R ₁ =C ₂ H ₄ ; R ₂ =H; R ₃ =ethyl; n=4) was added to an external circulation spray reactor with an effective volume of 10 L Ethylene carbonate. The reaction device was started, and the starting material was heated to 60° C. through a heat exchanger, and carbon dioxide was introduced into the reaction system until the pressure was 0.3 MPa. 4.0Kg of ethylene oxide and 4.0Kg of carbon dioxide (equimolar amount) were continuously added within 6 hours. During the feeding process, the feeding amount of alkylene oxide and carbon dioxide should be kept the same, and the system pressure should be maintained at 0.3MPa. After the addition was completed, the reaction was continued for 40 minutes. The reaction material was transferred to a flash tank, and after carbon dioxide was discharged, about 8.0Kg of ethylene carbonate (selectivity>99.5%) was obtained by distillation under reduced pressure, and the catalyst-containing residue was used as the starting material for recycling.

Example 6:

2.0Kg containing 80g bifunctional catalyst (X is bromide anion; R ₁ =C ₂ H ₄ ; R ₂ =H; R ₃ =ethyl; n=4) was added to an external circulation spray reactor with an effective volume of 10 L Ethylene carbonate. The reaction device was started, and the starting material was heated to 60° C. through a heat exchanger, and carbon dioxide was introduced into the reaction system until the pressure was 0.3 MPa. 4.0Kg of ethylene oxide and 4.0Kg of carbon dioxide (equimolar amount) were continuously added within 2 hours. During the feeding process, the feeding amounts of alkylene oxide and carbon dioxide should be kept the same, and the system pressure should be maintained at 0.3MPa. After the addition was completed, the reaction was continued for 40 minutes. The reaction material was transferred to a flash tank, and after carbon dioxide was discharged, about 8.0Kg of ethylene carbonate (selectivity>99.5%) was obtained by distillation under reduced pressure, and the catalyst-containing residue was used as the starting material for recycling.

Claims (3)

1. a method for the preparation of cyclic carbonate by an external circulation spray type gas-liquid contact technique, is characterized in that, adopts the external circulation spray reactor, takes the bifunctional catalyst as catalyzer, at the reaction pressure of 0.3～3.0MPa and 60～150 ℃ Under the reaction temperature of ℃, carbon dioxide and alkylene oxide are used as raw materials to carry out a coupling reaction to prepare cyclic carbonate; the specific reaction process is as follows: The cyclic carbonate containing the catalyst is added to the external circulation spray reactor, the starting material is heated to the reaction temperature through the heat exchanger, and carbon dioxide is introduced to the reaction system pressure to be the reaction pressure; Oxyalkane and carbon dioxide, and keep the reaction pressure; after the feeding is finished, continue to react until all the alkylene oxide is consumed, then transfer the reaction material in the external circulation spray reactor to the flash tank, discharge the carbon dioxide, and distill under reduced pressure to obtain Cyclic carbonate, the residual liquid containing catalyst is recycled as the next batch of reaction starting materials; The mass ratio of the alkylene oxide to the catalyst is 50:1 to 50000:1; The molar ratio of the alkylene oxide to carbon dioxide is 1:1. 2. the method for preparing cyclic carbonate by a kind of external circulation spray type gas-liquid contact process according to claim 1, is characterized in that, described catalyzer is tetradentate Schiff base aluminum complex, and contains a or multiple quaternary ammonium salt or quaternary phosphonium salt groups, the structure of which is: where: : indicates the connection position; R ₂ =H, CH ₃ , CH ₂ CH ₃ or Ph; R ₃ =C ₁ -C ₆ alkyl or phenyl; X=F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , CH ₃ COO ^- , CCl ₃ COO ^- , CF ₃ COO ^- , ClO ₄ ^- , BF ₄ ^- , BPh ₄ ^- , N ₃ ^- , right Toluic acid, p-toluenesulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2,4-dinitrophenol oxygen, 3,5-dinitro oxyphenol, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, 3,5-difluorophenoloxy, 3,5-di-trifluoromethylphenoloxy, or pentafluorophenol Oxygen anion; n=1-5. 3. the method for preparing cyclic carbonate by a kind of external circulation spray type gas-liquid contact process according to claim 1 and 2, is characterized in that, described alkylene oxide is propylene oxide or ethylene oxide.