Effect of Support Species on Performance of Transition Metal-based Catalysts for Propane Dehydrogenation with Co-feeding of H₂S

Abstract

This study investigated the effect of catalyst supports (SiO₂, γ-Al₂O₃, ZrO₂, CeO₂, MgO) on the performance of transition metal (Fe, Co, Ni) catalysts for propane dehydrogenation (PDH) with co-feeding of hydrogen sulfide (H₂S). Evaluation of the catalyst activity indicated that inert SiO₂ is a suitable support for the PDH catalysts. The SiO₂-supported Fe catalysts showed the highest activity and selectivity among the investigated catalysts. In order to clarify the effect of the support species on the structure and electronic state of the catalyst components, X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), and X-ray photoelectron spectroscopy (XPS) were used to characterize the various Fe-loaded catalysts. From Fe K-edge X-ray absorption near edge structure (XANES) analysis, it is deduced that the catalysts in which Fe was in a higher oxidation state showed better performance for PDH with co-feeding of H₂S. When SiO₂ and Al₂O₃ were used as the supports, divalent and trivalent Fe cations were detected by XPS analysis. Such high-valence Fe species can accept an electron from an intermediate species, thereby enhancing the dehydrogenation performance.