阅读说明：本技术 碳酸二甲酯的制备方法 (Preparation method of dimethyl carbonate ) 是由 卢健行 刘守国 卢建功 卢建智 姚珊珊 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种碳酸二甲酯的制备方法,以二氧化碳和甲醇为原料,在固定床反应器中加入催化剂,通入CO<Sub>2</Sub>吹扫,继续通入CO<Sub>2</Sub>并加热温度至120-140℃,保持恒温,在压力0.5-0.8MPa条件下加入甲醇,充分反应得碳酸二甲酯；所述催化剂为负载型催化剂,包括活性中心和载体；所述活性中心为过渡金属,所述载体包括二氧化硅、氧化铝和碱金属或碱土金属中的一种。本发明采用双金属活性中心共同作用,提高催化剂活性的同时既提高了反应转化率和目的产物的选择性。(The invention discloses a preparation method of dimethyl carbonate, which takes carbon dioxide and methanol as raw materials, adds a catalyst into a fixed bed reactor, and introduces CO 2 Purging, continuously introducing CO 2 Heating to 120-140 deg.C, maintaining constant temperature, adding methanol under 0.5-0.8MPa, and reacting to obtain dimethyl carbonate; the catalyst is a supported catalyst and comprises an active center and a carrier; the active center is transition metal, and the carrier comprises silicon dioxide, aluminum oxide andOne of an alkali metal or an alkaline earth metal. The invention adopts the combined action of the bimetallic active centers, improves the activity of the catalyst, and simultaneously improves the reaction conversion rate and the selectivity of a target product.)

1. A preparation method of dimethyl carbonate is characterized by comprising the following steps: carbon dioxide and methanol are taken as raw materials, a catalyst is added into a fixed bed reactor, and CO is introduced₂Purging, continuously introducing CO₂Heating to 120-140 deg.C, maintaining constant temperature, adding methanol under 0.5-0.8MPa, and reacting to obtain dimethyl carbonate; the catalyst is a supported catalyst and comprises an active center and a carrier; the active center is a transition metal, and the carrier comprises silicon dioxide, aluminum oxide and one of alkali metal or alkaline earth metal.

2. The method for preparing dimethyl carbonate according to claim 1, wherein: the active center of the catalyst comprises at least two of Co, Cu, Mn, Ni and Mo.

3. The method for preparing dimethyl carbonate according to claim 1, wherein: the catalyst carrier contains SiO₂Is 45-90% by mass, A1₂O₃The mass percentage is 5-30%.

4. the method for preparing dimethyl carbonate according to claim 1, wherein: the alkali metal or alkaline earth metal in the carrier is one of Rb, Cs, Mg and Sr.

5. The method for preparing dimethyl carbonate according to claim 4, wherein: the mass fraction of alkali metal and alkaline earth metal in the carrier is 5-20%.

6. The method for preparing dimethyl carbonate according to claim 1, wherein: the reaction temperature is 140 ℃ and the reaction pressure is 0.6 MPa.

7. The method for preparing dimethyl carbonate according to claim 1, wherein: the catalyst carrier is prepared by the following method: under the condition of stirring, uniformly mixing an alkali metal or alkaline earth metal precursor with a silicon dioxide and alumina precursor aqueous solution at the temperature of 20-85 ℃, adding acid to adjust the pH value to 0.5-5.5, continuously stirring, carrying out spray drying and forming on the mixture to obtain spherical particles with the particle size of 50-100 mu m, and roasting in an air atmosphere to obtain the carrier.

Technical Field

The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of dimethyl carbonate.

Background

Dimethyl Carbonate (DMC), chemical structure formula is CH₃O-CO-CH₃O is an important environment-friendly green organic chemical raw material, and because the structure of the O has methyl, carbonyl, methoxy and other groups, the O can replace phosgene to be used as a carbonylation agent, dimethyl sulfate to be used as a methylation agent and methyl tert-butyl ether to be used as an environment-friendly gasoline additive. On the other hand, the dimethyl carbonate is taken as a raw material, can be developed and prepared into various fine special chemicals with high added values, and has wide application in the fields of medicines, pesticides, synthetic materials, dyes, lubricating oil additives, food flavoring agents, electronic chemicals and the like.

Currently, the industrial synthesis of dimethyl carbonate mainly comprises a phosgene method, a methanol oxidative carbonylation method, an ester exchange method, a methanol urea method and the like. The direct synthesis of DMC from carbon dioxide and methanol is a hot point studied in recent years, and the reaction method is considered to be the most economical and safe synthesis method without any solvent and pollution discharge, but because of the stability of carbon dioxide, the reaction for directly synthesizing DMC from carbon dioxide and methanol as raw materials is difficult to perform thermodynamically, so that the development of a high-activity catalyst to promote the activation of carbon dioxide and the improvement of the reaction conversion rate are key points of the whole process.

disclosure of Invention

In order to make up the defects of the prior art, the invention provides the preparation method of the dimethyl carbonate, and the preparation method has good catalytic effect of directly preparing the dimethyl carbonate by taking methanol and carbon dioxide as raw materials.

The invention is realized by the following technical scheme:

The preparation method of the dimethyl carbonate is characterized in that: carbon dioxide and methanol are taken as raw materials, a catalyst is added into a fixed bed reactor, and CO is introduced₂Purging, continuously introducing CO₂Heating to 120-140 deg.C, maintaining constant temperature, adding methanol under 0.5-0.8MPa, and reacting to obtain dimethyl carbonate; the catalyst is a supported catalyst and comprises an active center and a carrier; the active center is a transition metal, and the carrier comprises silicon dioxide, aluminum oxide and one of alkali metal or alkaline earth metal.

Preferably, the catalyst active center comprises at least two of Co, Cu, Mn, Ni and Mo.

Preferably, the catalyst carrier contains SiO₂Is 45-90% by mass, A1₂O₃the mass percentage is 5-30%.

Further, the alkali metal or alkaline earth metal in the catalyst carrier is one of Rb, Cs, Mg and Sr.

Furthermore, the mass fraction of the alkali metal and the alkaline earth metal in the catalyst carrier is 5-20%.

Preferably, the reaction temperature is 140 ℃ and the reaction pressure is 0.6 MPa.

Preferably, the catalyst carrier is prepared by adopting the following method: under the condition of stirring, uniformly mixing an alkali metal or alkaline earth metal precursor with a silicon dioxide and alumina precursor aqueous solution at the temperature of 20-85 ℃, adding acid to adjust the pH value to 0.5-5.5, continuously stirring, carrying out spray drying and forming on the mixture to obtain spherical particles with the particle size of 50-100 mu m, and roasting in an air atmosphere to obtain the carrier.

The invention has the beneficial effects that: the invention adopts the combined action of the bimetallic active centers, improves the activity of the catalyst, improves the reaction conversion rate and the selectivity of a target product, and under the reaction condition of the invention, the selectivity of the dimethyl carbonate is close to 100 percent, the catalyst can obviously reduce the reaction pressure, and the selectivity and the total carbon conversion rate of the dimethyl carbonate are high, thereby being hopeful to realize industrialized expanded production.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments thereof to assist those skilled in the art in providing a more complete, accurate and thorough understanding of the inventive concept and aspects thereof, and the scope of the present invention includes, but is not limited to, the following examples, and any modifications in the details and form of the technical aspects thereof that fall within the spirit and scope of the present application are intended to be included therein.