Selective Decarboxylation of Fatty Acids Catalyzed by Pd-Supported Hierarchical ZSM‑5 Zeolite

Abstract

Decarboxylation of fatty acids is an interesting route for the production of renewable long-chain hydrocarbons that could replace fossil resources in the formulation of diesel and jet range fuels. The results reported in the present work demonstrate that Pd supported on hierarchical ZSM-5 zeolite allows for the decarboxylation of different fatty acids (stearic, oleic, and palmitic acids) to proceed under mild operation conditions (T = 250 °C and PH2 = 6 bar) with over 90% selectivity toward middle distillate hydrocarbons and conversions in the range of 60–85%. This outstanding performance has been attributed to a combination of high accessibility and tailored acidity in the zeolitic support that favors the metal dispersion and promotes the interaction between Pd and acid sites. The presence of a hydrogen atmosphere, under low-pressure conditions, is required for activating the Pd sites. It is also noteworthy that the catalyst could be reused after washing with n-dodecane, retaining 74% of its initial stearic acid conversion with just a minor variation in the yield of C17 hydrocarbons.