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 along with the diffusional removal of the small molecules through thin film. Among several kinetic constants, the polycondensation reaction rate constant k 1 (= k 8 ) and diester group degradation reaction rate constant k 7 have an influence over the degree of polymerization. The values of k 1 (= k 8 ) and k 7 for 0.05 wt% Sb 2 O 3 were obtained as curve‐fit values: (1) k 1 (= k 8 ) = 3.4 × 10 6 exp(− 18.500/RT′) (L/mol‐min); (2) k 7 = 1.3 × 10 11 exp(− 37,800/RT′) (min −1 ). Effects of the film exposure time, reduced pressure of vacuum, temperature, the initial terephthalic acid (TPA)/ethylene glycol (EG) mole ratio, the initial degree of polymerization, and catalysts were well explained by the model.