Mechanisms and Kinetics of Degradation of Polystyrene in Supercritical Methanol

摘要

The degradation of polystyrene(PS) in supercritical methanol was carried out under reaction temperatures ranging from 340 oC To 420 ?? And pressures of 10 Mpa to 30 Mpa. The selectivity of liquid products was investigated at various reaction conditions. As the reaction proceeded, the selectivity of styrene monomer and dimmer decreased, whereas that of the rest (I.e.,toluene, ethyl benzene, isopropyl benzene and 3-phenyl propanol etc.) increased. The mechanisms of decomposition reaction could be reasoned by analyzing products. The kinetic behavior of PS in supercritical methanol had been investigated. The degradation processes of PS in such supercritical fluids could be formulated by the first-order kinetic law at the initial stage of reaction. The activation energy for the degradation in supercritical methanol was evaluated to be 117.2 kJ/mol and it was also compared with activation energies for depolymerization in other supercritical fluids and that for thermal pyrolysis