Effect of titanium dioxide on direct esterification between terephthalic acid and ethylene glycol

Abstract

AbstractExperiments at various concentrations for A and B kinds of titanium dioxide were made in the pilot plant, and the effect of titanium dioxide on continuous esterification between terephthalic acid and ethylene glycol was obtained. Reaction rate constants of the reaction scheme reported by Yamada et al. (1985) were determined o fit with the experimental data obtained. It was found that titanium dioxide ([TDO]) does not exert an influence on the reaction rate constants of k1, k2, and k4 but does on the reaction rate constants of k3, k5, k6, and k7 as follows: kl = 1.5657 × 109 exp(−19,640/RT) k2 = 1.5515 × 108exp(−18,140/RT) k3 = (0.10[TDO] + 1) × 3.5165 × 109 exp(−22,310/RT) k4 = 6.7640 × 107 exp(−18,380/RT) k5 = (0.08[TDO] + 1) × 7.7069 exp(−2,810/RT) k6 = (0.04[TDO] + 1 ) × 6.2595 × 106 exp(−14,960/RT) k7 = (0.60[TDO] + 1) × 2.0583 × 1015 exp(−42,520/RT) for B kind k7 = (0.085714[TDO] + 1) × 2.0583 × 1015 exp(−42,520/RT) for A kind Applying these reaction rate constants, simulation of continuous esterification in the first tank reactor was made and the following results were obtained ( 1) The acceleration effect of titanium dioxide on the esterification reaction is minor, and there is hardly any difference in the effect on the esterification due to kinds of titanium dioxide. ( 2 ) The amount of diethylene glycol formation largely varies with kinds of titanium dioxide.