Enhanced catalytic cracking of n-hexane cracking to olefin via rational design of tandem vanadium oxide-based catalyst on ZSM-5

Abstract

Catalytic cracking of naphtha to produce olefins using ZSM-5 can fulfill the growing demand for light olefins and the energy problem. In the current work, vanadium oxide in different supports was mixed with ZSM-5 as a tandem catalyst for oxidative cracking of n-hexane to light olefins. The results showed that adding vanadium as a tandem catalyst with ZSM-5 increased n-hexane conversion to 68.8 % for VOx/Al₂O₃ and 86.7 % for VOx/SiO₂ addition. Selectivity to light olefin was significantly changed due to the oxidative dehydrogenation reaction in the vanadium active site. The position and proximity of the metal oxide and acid sites determine the reaction pathway and product distribution. A stability test showed that the conversion of n-hexane decreased from 58 % to 37 %. Still, the selectivity to olefin was stable at 60 % due to the carbon formation blocking the acid site, not the metal oxide sites.