CN109232250A

CN109232250A - A method of preparing dimethyl carbonate

Info

Publication number: CN109232250A
Application number: CN201811239569.8A
Authority: CN
Inventors: 成怀刚; 王波; 潘子鹤; 程芳琴
Original assignee: Shanxi University
Current assignee: Shanxi University
Priority date: 2018-10-23
Filing date: 2018-10-23
Publication date: 2019-01-18

Abstract

本发明涉及一种制备碳酸二甲酯的方法，属于碳酸二甲酯的生产工艺技术领域，解决在均相催化剂酯交换法合成碳酸二甲酯的生产中存在催化剂分离难、分离负荷大、能耗高的问题。解决方案为：将反应原料甲醇与碳酸乙烯酯按照摩尔比(3~12):1加入反应釜中，开启反应釜的搅拌和恒温装置，并控制反应釜内的温度范围为30℃‑60℃；S2、待反应釜内的温度达到所需温度并稳定后，通过进样注射器向反应釜中加入催化剂；S3、催化剂催化反应原料反应1.5 h后结束，收集产物，即得到碳酸二甲酯。本发明维持碳酸二甲酯高选择性的基础上，降低了均相催化剂甲醇钠的用量，缓解传统工艺中均相催化剂分离难、分离过程能耗高的问题、流程简单、实用性强、易于操作和使用。The invention relates to a method for preparing dimethyl carbonate, belongs to the technical field of production technology of dimethyl carbonate, and solves the problems of difficult catalyst separation, large separation load and energy in the production of homogeneous catalyst transesterification method to synthesize dimethyl carbonate. problem of high consumption. The solution is: add the reaction raw material methanol and ethylene carbonate into the reaction kettle according to the molar ratio (3~12): 1, turn on the stirring and constant temperature device of the reaction kettle, and control the temperature range in the reaction kettle to be 30 ℃-60 ℃ ; S2, after the temperature in the reaction kettle reaches the required temperature and is stable, add a catalyst to the reaction kettle through a sample injection syringe; S3, the catalyst catalyzes the reaction of the raw materials for 1.5 h and ends, and collects the product to obtain dimethyl carbonate. On the basis of maintaining the high selectivity of dimethyl carbonate, the invention reduces the amount of sodium methoxide of the homogeneous catalyst, alleviates the problems of difficult separation of the homogeneous catalyst and high energy consumption in the separation process in the traditional process, the process is simple, the practicability is strong, and the operation and use.

Description

A method of preparing dimethyl carbonate

Technical field

The invention belongs to the technical field of producing of dimethyl carbonate, in particular to a kind of side for preparing dimethyl carbonate Method.

Background technique

Ethylene carbonate and methanol ester-interchange method are one of the main production technologies of Synthesis of dimethyl carbonate (DMC).Catalysis Agent is the core link of the reaction, and presently used catalyst can be divided into homogeneous catalyst and heterogeneous catalyst two major classes, homogeneously The characteristics of catalyst is that activity is good, and yield is high, and selectivity is high, and technology is more mature, but is not easy to separate with product and is difficult to repeat It utilizes；The activity and selectivity of heterogeneous catalyst will generally be inferior to homogeneous catalyst, but be easier to separate with product, be catalyzed Recycling for agent can reduce cost.Currently, being catalyzed ethylene carbonate and the friendship of methanol ester using sodium methoxide as homogeneous catalyst During changing reaction Synthesis of dimethyl carbonate, the selectivity of dimethyl carbonate may be implemented up to 96.3%.In heterogeneous catalysis Under conditions of MgO/NaY, the selectivity of dimethyl carbonate is 94.3%.

In short, there are catalyst separation hardly possiblies, separation in the production of homogeneous catalyst synthesis of dimethyl carbonate via transesterification The problem that load is big, energy consumption is high.

Summary of the invention

In order to solve deficiency in the prior art, the purpose of the present invention is maintaining dimethyl carbonate selectively basicly stable Under the premise of, try the dosage for reducing homogeneous catalyst sodium methoxide, slows down the separation of homogeneous catalyst sodium methoxide to a certain extent Difficult problem.Based on this it is contemplated that using sodium methoxide/MgO- γ Al₂O₃Catalyst concerted catalysis ethylene carbonate and methanol ester Exchange process prepares the technology of dimethyl carbonate, under the premise of maintaining dimethyl carbonate highly selective, reduces homogeneous catalyst first The dosage of sodium alkoxide alleviates catalyst sodium methoxide in the load of separation process.

The present invention is achieved by the following technical programs.

A method of preparing dimethyl carbonate, comprising the following steps:

S1, by reaction raw materials methanol and ethylene carbonate according to molar ratio (3 ~ 12): 1 be added reaction kettle in, open reaction kettle Stirring and thermostat, and controlling the temperature range in reaction kettle is 30 DEG C -60 DEG C；

S2, for 30 DEG C -60 DEG C and after stablizing, catalysis is added into reaction kettle by sampling injector after the temperature in reaction kettle Agent, catalyst quality account for 0.1 wt%-0.5 wt% of reaction raw materials methanol and ethylene carbonate gross mass in step S1, catalyst Including homogeneous catalyst and heterogeneous catalysis, the homogeneous catalyst is sodium methoxide, and the heterogeneous catalysis is MgO- γ Al₂O₃, the mass ratio of homogeneous catalyst and heterogeneous catalysis is (0.2 ~ 1): 1；

S3, catalyst reaction raw materials terminate after reacting 1.5 h-3h, collect product to get dimethyl carbonate is arrived.

Further, homogeneous catalyst uses alkaline ionic liquid catalyst to replace sodium methoxide in the step S2, non-equal Phase catalyst replaces MgO- γ Al using supported basic catalyst₂O₃。

Compared with prior art the invention has the benefit that

A kind of method preparing dimethyl carbonate provided by the invention, it is easily operated, the work improved efficiency is played in production With；The dosage of homogeneous catalyst sodium methoxide can be reduced under the premise of maintaining dimethyl carbonate highly selective, mitigation is homogeneously urged The load of agent sodium methoxide during the separation process reduces energy consumption, improves the added value of production process.

In conclusion present invention process process is simple, can alleviate on the basis of maintaining dimethyl carbonate highly selective It is the difficult problem of conventional homogeneous catalyst sodium methoxide separation, practical.

Specific embodiment

The present invention is further illustrated below by specific embodiment.

Embodiment one

A method of dimethyl carbonate is prepared, is included the following steps:

S1, reaction raw materials methanol and ethylene carbonate are added in reaction kettle according to molar ratio 5:1, open stirring and constant temperature dress It sets, controlled at 60 DEG C；

S2, after the temperature in reaction kettle reaches 60 DEG C and stablizes, pass through sampling injector be added catalyst, control homogeneous catalysis Sodium methoxide and with heterogeneous catalysis MgO- γ Al₂O₃Mass ratio be 1:1, catalyst amount be 0.5 wt%(catalyst quality Account for the mass ratio of carbon reactant vinyl acetate and methanol)；

Reaction was completed and collects product after S3,1.5 h of reaction progress.

The selectivity of obtained dimethyl carbonate product is 96.5%, the dosage phase with conventional homogeneous catalyst sodium methoxide Than homogeneous catalyst sodium methoxide dosage reduces 50% in this patent.

Embodiment two

Method and workflow are same as Example 1, the difference is that step S1:

S1, reaction raw materials methanol and ethylene carbonate are added in reaction kettle according to molar ratio 12:1, open stirring and constant temperature dress It sets, controlled at 60 DEG C；

S2, after the temperature in reaction kettle reaches 60 DEG C and stablizes, pass through sampling injector be added catalyst, control homogeneous catalysis Agent sodium methoxide and heterogeneous catalysis MgO- γ Al₂O₃Mass ratio be 1:1, catalyst amount be 0.5 wt%(catalyst quality Account for the mass ratio of carbon reactant vinyl acetate and methanol)；

Embodiment three

Method and workflow are same as Example 2, the difference is that step S2 and S3:

Catalyst is added after the temperature in reaction kettle reaches 60 DEG C and stablizes, through sampling injector in S2, controls homogeneous catalysis Agent sodium methoxide and heterogeneous catalysis MgO- γ Al₂O₃Mass ratio be 0.5:1, catalyst amount be 0.5 wt%(catalyst matter Amount accounts for the mass ratio of carbon reactant vinyl acetate and methanol)；

Reaction was completed and collects product after 3 h of S3 reaction progress.

The selectivity of obtained dimethyl carbonate product is 96.5%, the dosage phase with conventional homogeneous catalyst sodium methoxide Than homogeneous catalyst sodium methoxide dosage reduces 67% in this patent.

The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any It is familiar with those skilled in the art in the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of, should all contain Lid is within protection scope of the present invention.Therefore, protection scope of the present invention should be based on the protection scope of the described claims.

Claims

1. a method for preparing dimethyl carbonate, is characterized in that comprising the following steps:

S1, reacting raw material methanol and ethylene carbonate are added in the reactor according to mol ratio (3～12): 1, open the stirring and constant temperature device of the reactor, and control the temperature range in the reactor to be 30 ℃-60 ℃;

S2. After the temperature in the reaction kettle is 30°C-60°C and stabilized, add a catalyst to the reaction kettle through a sample injection syringe, and the catalyst mass accounts for 0.1wt%-0.5% of the total mass of the reaction raw materials methanol and ethylene carbonate in step S1. wt%, the catalyst includes a homogeneous catalyst and a heterogeneous catalyst, the homogeneous catalyst is sodium methoxide, the heterogeneous catalyst is MgO-γAl ₂ O ₃ , and the mass ratio of the homogeneous catalyst to the heterogeneous catalyst is ( 0.2~1):1;

S3. The catalyst catalyzes the reaction of the raw materials for 1.5 h to 3 h and ends, and the product is collected to obtain dimethyl carbonate.

2. a kind of method for preparing dimethyl carbonate according to claim 1, is characterized in that: in described step S2, homogeneous catalyst adopts basic ionic liquid catalyst to replace sodium methoxide, and heterogeneous catalyst adopts solid-supported A basic catalyst replaces MgO-γAl ₂ O ₃ .