Catalytic deoxygenation of stearic acid into olefins over Pt catalysts supported on MOF-derived metal oxides†

Abstract

In this study, three different metal oxides derived from metal–organic frameworks (MOFs), including CeO₂, ZrO₂, and Fe₂O₃ were used as porous supports for loading Pt nanoparticles, and the supported catalysts (viz., Pt/CeO₂, Pt/ZrO₂, and Pt/Fe₂O₃) were evaluated for the catalytic deoxygenation of stearic acid to produce olefins by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Interestingly, Pt/CeO₂ and Pt/Fe₂O₃ catalysts demonstrated high selectivity for olefins or aromatics, respectively, with alkanes as minor products, while the Pt/ZrO₂ catalyst demonstrated the lowest deoxygenation efficiency. Among them, the Pt/CeO₂ catalyst demonstrated the highest deoxygenation efficiency due to its highest oxygen vacancy density and the largest specific surface area (53 m² g⁻¹). It also demonstrated the highest selectivity for olefins (41%) due to the in situ partial formation of the bimetallic PtCe phase during the catalytic reaction at high temperature, which facilitates the decarbonylation pathway and leads to the formation of olefins as the main product. In addition, experimental optimizations of the reaction parameters were conducted on the designed Pt/CeO₂ catalyst to further enhance olefin selectivity. Importantly, the Pt/CeO₂ catalyst also maintained high olefin selectivity and stearic acid conversion even after six consecutive cycles. Therefore, this work has provided an alternative route to produce olefins via the decarbonylation of stearic acid over a supported Pt/CeO₂ catalyst.