Abstract
Pt and Gd loaded ZSM-5 catalysts were synthesized by ion exchange method to investigate the effect of metal promoters on catalyst activity, coking and regeneration during military aviation fuel (JP-8) cracking into petroleum gas (PG) at 723K. Multiple cracking and regeneration cycles were performed over the ZSM-5 based catalysts and their crystalline structure, oxidation profile, coke band and acidity were characterized. It was revealed that addition of Gd metal to the ZSM-5 catalyst prevented formation of complex aromatic coke and increased the number of Lewis acid sites, while Pt promoted ZSM-5 catalyst showed a decrease in the coke oxidation temperature. The effect of Pt and Gd promoters enhanced the coke burn-off ability, formed hydrogen rich carbon species and reduced oxidation temperature of coke substantially. Furthermore, agglomeration of Pt particles was partially impeded by coexisting Gd metal on the regenerated ZSM-5 catalyst. Synergetic effects of Pt and Gd promoters stabilized the PG yield and product distribution over the Pt–Gd/ZSM-5 catalyst during the cracking and regeneration cycles.