Efficient upgrading of polyolefin plastics into C5–C12 gasoline alkanes over a Pt/W/Beta catalyst

Abstract

A Pt/W/Beta catalyst was developed for direct and efficient hydrogenolysis of low density polyethylene (LDPE) into C₅–C₁₂ gasoline alkanes with a high yield of 63.6 wt% (yield of C₁–C₁₃ light alkanes is 94.0 wt%) at 250 °C and 3.0 MPa H₂ within 1.0 h. The obtained gasoline alkanes have a narrow carbon number distribution and contain abundant mono-branched isomers, which were attributed to well-dispersed Pt species and proximity of the cooperating active sites, especially the moderate acidity upon the introduction of 0.5 wt% tungsten species. The catalyst was also applicable to hydrogenolysis of light low density polyethylene (LLDPE), high density polyethylene (HDPE) and polypropylene (PP) to obtain the valuable gasoline alkanes (C₅–C₁₂) in high yield (50.8–73.5 wt%). The C–C bond cleavage of plastics over the Pt/W/Beta catalyst was found to occur through medium to long-chain hydrocarbons (n-C_x, x > 13) based on experiments performed using docosane (n-C₂₂ alkane) as the model feedstock.