Hydrothermal preparation of a platinum-loaded sulphated nanozirconia catalyst for the effective conversion of waste low density polyethylene into gasoline-range hydrocarbons

Abstract

A platinum-loaded sulphated nanozirconia (Pt/nano ZrO₂–SO₄) bifunctional metal–acid catalyst was synthesized using a hydrothermal process. The nano ZrO₂–SO₄ was initially prepared by dispersing the nano ZrO₂ in H₂SO₄, followed by wet impregnation via heating in an aqueous PtCl₄ solution. This material was subsequently calcined and reduced under hydrogen gas to produce the catalyst. The Pt/nano ZrO₂–SO₄ was found to be a highly active, selective and stable solid acid catalyst for the conversion of waste low density polyethylene (LDPE) to high value hydrocarbons. The catalytic activity and stability of this material were evaluated during the hydrocracking of waste LDPE while optimizing the reaction temperature, time and catalyst-to-feed ratio. The activity of catalyst prepared by hydrothermal was attributed to highly dispersion of Pt species interacting with the support and inhibition of the agglomeration process. The impregnation method of hydrothermal generated highly active and selective catalyst with Pt loads of 1 wt%. The hydrocracking of waste LDPE over Pt/nanoZrO₂–SO₄ at 250 °C for 60 min with a catalyst-to-feed proportion of 1 wt% gave the largest gasoline fraction.