Method of continuous production of highly pure bisphenole-A

摘要

A process is claimed for recovering bisphenol A (BPA) with a purity of at least 99.75% and a Hazen colour of 5-10 from a reaction mixt. produced by reacting acetone with phenol in the presence of an SO3H-contg. ion exchanger opt. modified with a mercapto amine, thiazolidine and/or thiocarboxylic acid, where the reaction mixt. comprises 25-35 wt.% p,p-BPA in phenol. The process comprises: (1) feeding the mixt. at 65-75 deg.C into a cascade of two or more series-connected crystallisers; (2) circulating the mixt. within each crystalliser at a rate of at least 500 m<3>/hr. for at least 3 hrs.; (3) adjusting the temp. gradient over the whole cascade from 70 deg.C in the first crystalliser to 40 deg.C in the last; (4) collecting BPA adduct crystals comprising ca. 60%, p,p-BPA and ca. 40% phenol by filtration; and (5) removing the phenol from the adduct crystals.