PROCESS FOR THE PURIFICATION OF BENZENECARBOXYLIC ACID ESTERS BY CRYSTALLIZATION

摘要

Procedure for the purification of benzenecarboxylic acids and esters of benzenecarboxylic acids, especially dimethyl terephthalate, characterized in that the product dissolved in a solvent, especially methanol, is subjected to a continuous two-stage crystallization process with controlled nucleation processes, solvent supersaturation and crystal growth, with nucleation, solvent supersaturation and nucleus growth up to a certain grain size, preferably 100μ at a temperature between about 100 and 88ºC, preferably 90ºC, in the first stage at a nucleation forming apparatus, and in a second stage the growth of the crystals is completed in a grain growth apparatus in the crystallization margin with small relative supersaturation up to an equally determined grain size, preferably 250 to 350μ, with moderate num mere revolutions in the range from 10 to 100 rpm. (Machine-translation by Google Translate, not legally binding)