Method for separating mixed diacid dimethyl ester

Abstract

The invention discloses a method for separating mixed diacid dimethyl ester. Mixed diacid dimethyl ester successively passes through a rectification tower 1, a rectification tower 2 and a rectification tower 3; dimethyl succinate is separated from the top of the rectification tower 1, dimethyl glutarate is separated from the top of the rectification tower 2, and dimethyl adipate is separated from the top of the rectification tower 3; the reflux ratio of the rectification tower 1, the rectification tower 2 or the rectification tower 3 is 0.5 to 3.0; the mixed diacid dimethyl ester is a product of esterification of methanol and mixed diacid by-produced in production of adipic acid, and comprises 10 to 30 wt% of dimethyl succinate, 40 to 60 wt% of dimethyl glutarate and 20 to 40 wt% of dimethyl adipate. With the method, the recovery rate and purity of dimethyl succinate, dimethyl glutarate and dimethyl adipate are more than 95 wt% and no less than 98%, respectively. According to the invention, a rectification apparatus is divided into the three rectification towers, each rectification tower is provided with 5 to 30 tower plates, the reflux ratio is controlled to be 0.5 to 3, energy consumption is low, the utilization rate of resources is high, and the advantages of easy realization of industrialization and low energy consumption are obtained.

Description

technical field [0001] The invention relates to a method for separating dimethyl succinate, dimethyl glutarate and dimethyl adipate from mixed dibasic acid dimethyl, belonging to the field of chemical industry. Background technique [0002] Dimethyl succinate, formula C 6 h 10 o 4 , Molecular weight 146.14, CAS No. 110-54-3, English name is Dimethylsuccinate, it is colorless and transparent liquid, it can synthesize polyester with diols such as ethylene glycol. Dimethyl succinate can be hydrolyzed to obtain high-value succinic acid. Dimethyl glutarate, formula C 7 h 12 o 4 , molecular weight 160.17, CAS No. 1119-40-0, English name Dimethyl glutarate, is a colorless transparent liquid, after hydrogenation can produce high-value pentanediol, and can also synthesize high-performance with diols such as ethylene glycol polyester. Dimethyl glutarate can be hydrolyzed to obtain high-value glutaric acid. Dimethyl adipate, formula C 8 h 14 o 4 , molecular weight 174.20, C...

AI Technical Summary

Problems solved by technology

[0009] 1. The dimethyl adipate with a high content was not separated from the mixed dibasic acid dimethyl, and the resources were not fully utilized;

[0010] 2. The reflux ratio of the dimethyl succinate distillation tower, that is, the first tower, is as high as 4.6~6.0, which is much higher than the reflux ratio range of 0.5~2.0 commonly used in industry, resulting in excessive energy consumption;

[0011] 3. The rectification of dimethyl glutarate requires the use of a dimethyl glutarate pre-distillation tower, the second tower, and a dimethyl glutarate distillation tower, the third tower. There are two rectification towers in total, and the investment in equipment is large. , complex control and operation

[0012] 4. The reflux ratio of the dimethyl glutarate pre-distillation tower, that is, the second tower, is as high as 5.4~6.5, which is much higher than the reflux ratio range of 0.5~2.0 commonly used in industry, resulting in excessive energy consumption;

[0013] 5. The reflux ratio of the dimethyl glutarate distillation column, that is, the third column, is as high as 9~15, which is much higher than the reflux ratio range of 0.5~2.0 commonly used in industry. The energy consumption is very high, the energy waste is very serious, and industrialization is difficult. very big

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