Catalytic degradation of polyethylene into fuel oil over mesoporous silica (KFS-16) catalyst

The thermal degradation of plastic polymers into fuel oil over mesoporous silica (KFS-16) catalyst has been investigated. The product yields, composition and degradation rate of polyethylene over KFS-16 were compared with those over solid acid catalyst (silica-alumina and zeolite) and non-catalytic thermal degradation. The initial rate of degradation of PE over KFS-16, which possesses no acid sites was as fast as that over silica-alumina (SA-1) and the yield of liquid products was higher. The composition of the liquid products of degradation over KFS-16 was different from that over SA-1 and similar to that of non-catalytic thermal degradation. SA-1 catalyst deactivated very rapidly due to coke deposition, whereas KFS-16 deactivated much more slowly. These findings over mesoporous silica suggest that the mesopores surrounded by the silica sheet may act as a flask for storing radical species for a long time and then long-lived radicals accelerate the degradation of plastics.