Catalytic pyrolysis of polyethylene: A comparison between pillared and restructured clays

•Clay based catalysts have been compared with H-ZSM5 in polyethylene cracking.•The clay based catalysts gave higher yields of liquid products in the C15–C20 range.•By selecting the appropriate catalyst, the choice between producing aliphatics and aromatics can be made.

In this work, three restructured smectite clays, namely a saponite, a montmorillonite, and a beidellite, as well as their Al- and Fe/Al-pillared derivatives, have been tested for their performance in the catalytic cracking of a medium-density polyethylene. All reduce the cracking process temperature to 300 °C, as compared with >650 °C for uncatalysed pyrolysis. Although generally less active than a selected H-ZSM5 (Si/Al = 235) zeolite, they are instead superior to this catalyst as regards liquid hydrocarbon formation.Different products categories can be obtained by different catalysts: in particular a choice between aliphatics and aromatics products can be made by utilising the appropriate catalysts.