Hydrocracking of virgin and post-consumer polymers

Abstract

With the growing concern around polymer waste sent to landfill and its environmental release, one effective route for polymer recycling is hydrocracking over bifunctional zeolites. Zeolite Beta impregnated with 1% Pt has demonstrated high conversion of single and mixed streams of virgin and post-consumer polymers, LDPE, HDPE, PP and PS under mild reaction conditions of 330 °C, 20 bar H2 and a 30 min reaction time. The PE and PP streams giving a similar mix of low molecular weight hydrocarbons with higher selectivity toward gases (typically, C3–C4) and also, obtaining high iso-to normal paraffin ratio. PS was readily converted into an aromatic-rich product under these mild conditions and demonstrated the ability to be a source of benzene and ethylbenzene for use as raw materials in further polymer production. Dealuminated zeolite USY with 1% Pt increased the selectivity toward liquid products and resulting in more naphtha (C5–C12) and heavier liquids (C13–C20).