Air oxidation of 2,6-diisopropylnaphthalene to 2,6-naphthalenedicarboxylic acid in liquid phase
The influences of catalyst concentration, reaction temperature and pressure, feed rate, and water content on the liquid phase oxidation of 2,6-diisopropylnaphthalene to 2,6-naphthalenedicarboxylic acid (2,6-NDCA)were studied in a 1 L titanium reactor using air as oxidant, acetic acid as solvent, and a Co-Mn-Br mixture as catalyst, and the optimum operation conditions were obtained in the experimental range.Meanwhile, the promotor effects of individual CO2 and Ni 2+ and their combined use on the activity of Co-Mn-Br catalyst were discussed.Based on the results of the batch experiments, a continuous process for making 2,6-NDCA was developed.The yield of 2,6-NDCA increased from 69% to 73% and the purity of 2,6-NDCA could be up to 95% with the increasing of reaction time.