Pt/ITQ-6 zeolite as a bifunctional catalyst for hydrocracking of waste plastics containing polystyrene

Abstract

Thermal and catalytic hydrocracking of polystyrene to fuels was compared. The use of a bifunctional (platinum and acidic sites) catalyst such as Pt/Ferrierite not only increases conversion but also selectivity to a wider and more interesting variety of products in the gasoline range (C5–C12). As polymer molecules present steric hindrance to access internal active sites in the catalyst, Pt/ITQ-6 was prepared by delamination to maximize the external surface of the catalyst while keeping its composition and type. Although Pt/ITQ-6 presented lower acidity than Pt/Ferrierite, it was mostly external and, thus, accessible to the reactants. In this way, Pt/ITQ-6 significantly improved activity and selectivity of Pt/Ferrierite. The performance of Pt/ITQ-6 when recycled polystyrene was used as reactant proved this catalyst is very promising for this application, although catalytic activity decreased as a consequence of plastic additives and impurities.