The invention relates to a process for refining
battery fluid grade
dimethyl carbonate from
coal to
ethylene glycol by-product
dimethyl carbonate through pressurization method coupled melt
crystallization. The process comprises the following steps: (1) materials are preheated: a
coal to
ethylene glycol product enters a normal-pressure T1 removal of light component
tower, light components such as methylal and
methyl formate are removed at the top of the T1 removal of light component
tower, a part of
dimethyl carbonate and
dimethyl oxalate are removed at the bottom of the T1 removal of light component
tower, side-draw produced
methanol and DMC close to the upper part of a material inlet of the tower are mixed, and the mixed material enters a T2 pressurization tower; (2) a side-draw producedDMC
azeotrope of the T1 tower enters the T2 pressurization tower, a DMC
azeotrope with a DMC content of about 15-18% is obtained from the top of the pressurization rectification tower, and DMC with acontent of 99.5% or more is obtained from the tower kettle; and (3) dimethyl
carbonate with a content of 99.5% enters a following film falling melt
crystallization device, freezing is performed, sweating is performed, dissolving is performed, and therefore the
battery fluid grade dimethyl
carbonate with a content of 99.99% is obtained. The pressurization coupled melt
crystallization separation process provided by the invention can remove more than 10 kinds of impurities in the
coal to
ethylene glycol by-product dimethyl
carbonate, and the product quality reaches 99.99%, and the obtained dimethyl carbonate can be applied to prepare
polycarbonate and a
lithium battery fluid.