摘要 |
<p>Inordinately slow crystallization at rate controlled evaporative cooling of terephthalic acid from liquid phase aqueous solutions also containing from 500 to 6,000 ppm p-toluic acid based on dissolved terephthalic acid at temperatures in the range of 400 DEG to 550 DEG F. can be overcome by more rapid continuous flash evaporation of solvent in two or more stirred crystallization zones to obtain a terephthalic acid product having 150 ppm or less p-toluic acid. Such product is readily separated from mother liquor by continuous centrifuge.</p> |