Naphtha catalytic cracking to olefins over zirconia–titania catalyst

Abstract

A zirconia–titania-based catalyst was synthesized by a co-participation method to study the catalytic cracking of heavy naphtha (dodecane) into high value-added olefins. The nanocrystal-sized catalysts were characterized and the cluster consisted of tetragonal ZrO₂ incorporated into anatase TiO₂. The catalyst was stable from hydrogen reduction while the surface acidity was increased as more ZrO₂ was incorporated into the TiO₂ framework. The catalytic cracking of naphtha was increased as the moderate catalytic acidity strength increased and the 50% Zr–Ti oxide catalyst delivered higher conversion between 85–95% with olefin yield around 55–60%. The surface acidity of the Zr–Ti catalyst promoted more cyclization reactions to produce benzene, toluene, and xylene (BTX). The study investigated steam catalytic cracking, which was slightly improved using a lower acidic Zr–Ti catalyst, while the propylene/ethylene ratio was unchanged. The time-on-stream study highlighted the stability of the catalyst with ZrO₂ incorporated into the TiO₂ framework, to promote olefin yield from naphtha catalytic cracking.