Pyrolysis characteristics of polystyrene and polypropylene in a stirred batch reactor

Abstract

Kinetic tests on pyrolysis of polystyrene (PS) and polypropylene (PP) were carried out with a thermogravimetric analysis (TGA) technique at the heating rate of 0.5, 1.0, and 2.0 °C min −1 in a stirred batch reactor. The polystyrene was mainly decomposed between 370 and 410 °C at the heating rates, whereas the polypropylene between 400 and 460 °C. The apparent energy of activation and the apparent order of reaction were determined at conversions from 1 to 100%. The ranges of apparent energies of activation of polystyrene were from 164 to 249 kJ mol −1 at conversions in the range of 1–100% and the apparent order of reaction was 0.32. The apparent energies of activation of polypropylene increased slowly from 208 to 288 kJ mol −1 and the apparent order of reaction was 0.01. The effects of heating rate on the product distribution have been studied. The selectivity of hydrocarbons corresponding to the styrene monomer and dimer was very high for the pyrolysis of polystyrene. The selectivity of specific hydrocarbons, however, was not observed for the case of polypropylene.