ANALYSIS OF A REACTOR WITH SURFACE RENEWAL FOR POLY(ETHYLENE-TEREPHTHALATE) SYNTHESIS

A mathematical model of a polycondensation reactor that can be used in the final stage for poly(ethylene terephthalate) (PET) is established and compared with experimental data obtained from a laboratory scale reactor with film renewal. Detailed side reactions are considered alon g with the diffusional removal of the small molecules through thin fil m. Among several kinetic constants, the polycondensation reaction rate constant k1(= k8) and diester group degradation reaction rate constan t k7 have an influence over the degree of polymerization. The values o f k1(= k8) and k7 for 0.05 wt% Sb2O3 were obtained as curve-fit values : (1) k1(+ k8) = 3.4 X 10(6) exp(- 18,500/RT') (L/mol-min); (2) k7 = 1 .3 x 10(11) exp(- 37,800/RT') (min-1). Effects of the film exposure ti me, reduced pressure of vacuum. temperature, the initial terephthalic acid (TPA)/ethylene glycol (EG) mole ratio. the initial degree of poly merization, and catalysts were well explained by the model.