Catalytic degradation of polymers: Part II- Degradation of polyethylene

Silica, alumina, silica-aluminas, and zeolites were screened as catalysts for polyethylene degradation in the range 200-600°C. More than 50% of the products in the distillate from the catalytic reactions at T>=400°C, for the more efficient catalysts, were in fractions up to C9 with a large amount of saturated and unsaturated isomers, at variance with the thermal degradation which gave products distributed over a wider spectrum of carbon atom numbers and with a rather small number of isomers. These different distributions, which were obtained by GC-MS analysis, gave helpful indications about the mechanism of degradation. Kinetic measurements and thermogravimetry provided further useful data for screening the catalysts, finding the best operating conditions, and eventually making significant comparisons with other polymer degradations.