Zeolite-Supported Pd and Pt Catalysts for Low-Temperature Hydrogenation of Naphthalene in the Absence and Presence of Benzothiophene

Abstract

The objective of this work is to explore the potential of zeolite-supported noble metal catalysts for low-temperature hydrotreating of distillate fuels. Zeolite-supported Pt and Pd catalysts were prepared using a mordenite (HM38) and a Y zeolite (HY) as support materials and were applied for hydrogenation of naphthalene in n-tridecane at 200 °C in the absence and presence of added benzothiophene. The results are also compared to those with Al2O3- and TiO2-supported Pt and Pd catalysts. Both Pd/HM38 and Pd/HY catalysts are substantially more active than Pd/Al2O3 and Pd/TiO2 catalysts, even when the former is used with less catalyst loading under lower H2 pressure. The same trend can be observed from comparing Pt/HM38 and Pt/HY catalysts with Pt/Al2O3 catalyst. The sulfur resistance as well as the activity of the catalysts also depends strongly on the type of support and metal. Addition of sulfur in the form of benzothiophene decreased the activity of all the catalysts tested. However, there appear to be significant improvements in sulfur tolerance of the noble metals when they are supported on zeolites, rather than Al2O3 or TiO2 supports. The Pd catalysts supported on both mordenite and Y zeolite showed higher sulfur tolerance than all the other catalysts. Overall, mordenite-supported Pd catalyst, Pd/HM38, showed the best activity and the highest resistance to sulfur poisoning.