COMPUTER AIDED DESIGN OF TRANSESTERIFICAT1ON REACTOR A STEP IN POLYCONDENSATION REACTION

Abstract

The PET synthesis mainly comprises of reactions (viz transesterfication, ester interchange and polycondensation). In this study a computer aided design model using a simplified kinetic scheme for homogeneously catalyzed transesterification process of DMT with ethylene glycol in a CSTR has been proposed and analysed. The performance of CSTR reactor has been evaluated and verified in terms of percent DMT conversion. The effects of feed molar ratio of the reactants, residence time and reaction temperature on the performance of the reactor have been studied and discussed. The results obtained in the study showed available trends as in the literature, however the effects of the residence time and reaction temperature studied add to more insight of the process. The EG to DMT molar ratio has been varied from 0.5 to 3.5 by keeping constant residence time (120 minutes), temperature (180°C) and concentration of catalyst (2x10-3 mol/ltr). It is found that there is an increase in the percent DMT conversion with feed molar ratio however, it approaches a constant value of about 72% at feed molar ratio around 2.7. The residence time has been varied from 60 minutes to 240 minutes by keeping constant molar ratio EG to DMT (2.0), temperature (180°C) and catalyst concentration (2x10-3 mol/ltr). It is found that it increases but there is no increase in the percent DMT conversion (72% maximum) beyond a residence time about 150 minutes. The temperature of the reaction has also been varied from 175°C to 192.5°C by keeping constant residence time (120 min), molar ratio of EG to DMT (2.0) and catalyst concentration (2x10-3 mol/ltr). It is found that it increases iii but there is no increase in the percent DMT conversion (71.5% maximum) obtained at and beyond a temperature of about 183°C. It can be seen that ultimate DMT conversion with respect to operating parameters studied viz. molar ratio, residence time and reaction temperature is about 72 percent maximum.