Hydroconversion of Perhydrophenanthrene over Bifunctional Pt/H‐USY Zeolite Catalyst

Abstract

AbstractIn petroleum refining, middle distillates are produced via hydroisomerization/hydrocracking processes using bifunctional catalysts often containing ultrastable Y (USY) zeolite. Petroleum fractions serving as feedstock for hydrocracking processes contain a majority of (poly)cyclic hydrocarbon molecules. Few studies on reaction mechanisms of hydrocracking of such polycyclic compounds are available. In this study the tricyclic phenanthrene molecule was used as model compound. Phenanthrene was hydrogenated on a Pt/alumina pre‐catalyst to perhydrophenanthrene, and subsequently hydrocracked over Pt/H‐USY zeolite. The feed consisted of 3 wt.% phenanthrene dissolved in n‐heptane. The reaction was performed at 280 °C and 60 bar, with a molar H2 to total hydrocarbon ratio of 7 mol/mol. The reaction products were analyzed using GCxGC‐FID/MS. This detailed analysis enabled identification of the reaction scheme involving skeletal isomerization, ring opening and fragmentation. New mechanistic insight is gained on relative reactivities of bridged and non‐bridged tricyclic naphthenes. Preferential hydrocracking routes were identified. The study provides insight in the products to be expected from polycyclic hydrocarbon isomerization and hydrocracking.