Process for preparing dibasic acid ester

Abstract

The invention relates to a method of preparing dibasic acid esters. Solid acid catalyst, dualistic carboxylic acid or dualistic carboxylic acid mixture, and low-carbon alcohol are added in a pre-esterification kettle; the addition amount of the solid acid catalyst is 1 to 10 percent of the quality of the dualistic carboxylic acid or the dualistic carboxylic acid mixture; the molar ratio of the alcohol and the dualistic carboxylic acid or the dualistic carboxylic acid mixture is 1 to 10:1; the reaction is performed under the normal atmosphere, wherein, the temperature ranges from 50 to 100 DEG C; the supernatant fluid of reaction products is delivered into the upper part of an esterification reactor; after the low-carbon alcohol is turned into vapour by passing through a carburetor, the low-carbon alcohol vapour enters into the lower part of the esterification reactor; the supernatant fluid and the low-carbon alcohol vapour effect the reflux reaction at a catalyst section of a continuous esterification reactor; reaction products are expelled from the bottom of the esterification reactor, and unreacted low-carbon alcohol and generated water are steamed from the top of the reactor; esterification reaction occurs under the normal atmosphere, the temperature ranges from 70 to 150 DEG C, the liquid airspeed is 0.1 to 0.7Kg / Kg*h, the airspeed of the low-carbon alcohol is 0.1 to 1.0Kg / Kg*h, and the percent conversion can reach more than 99 percent.

Description

Technical field: [0001] The invention relates to a method for preparing dibasic acid esters. Background technique: [0002] Dibasic esters are excellent cold-resistant plasticizers, which can endow products with excellent low-temperature softness, and have certain light and heat stability and water resistance. [0003] The prior art uses sulfuric acid or other inorganic liquid acids as catalysts to produce carboxylic acid esters, or reacts under certain pressure and higher temperature. The use of inorganic liquid acid as a catalyst has environmental pollution problems such as corrosion of equipment by inorganic liquid acid and treatment of three wastes of reaction products. For example, the disclosed process method of British Patent (GB143069) is: use concentrated sulfuric acid as catalyst, adopt tank reactor reaction, and the method for distilling removes water. [0004] Also have is the batch operation that carries out under stirring condition, and adopts batch reaction ...

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Problems solved by technology

[0004] Also have is the batch operation that is carried out under stirring condition, and adopts batch reaction to be unfavorable for the continuous industrial production of large-scale

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