Tuning the decarboxylation selectivity for deoxygenation of vegetable oil over Pt–Ni bimetal catalysts via surface engineering

Abstract

Alloy and bimetal structures are particularly important in developing highly active catalysts for energy conversion. Herein, Pt-skin (Ni–Pt/Al₂O₃), Ni-skin (Pt–Ni/Al₂O₃) and NiPt-skin (NiPt/Al₂O₃) catalysts were designed and synthesized by sequential impregnation of Pt and Ni on Al₂O₃. The surface structures of these catalysts were confirmed by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N₂ adsorption and desorption isotherm measurement (N₂-BET) and H₂ temperature programmed reduction (H₂-TPR). The Pt electronic states were tuned by the sub-layer of Ni on the catalyst's surface which was the key factor to decarboxylation. The NiPt alloy species was formed in the Ni–Pt/Al₂O₃ and NiPt/Al₂O₃ catalysts, and these two catalysts contained a higher content of Pt⁴⁺ species compared with the Pt–Ni/Al₂O₃ catalyst. The NiPt-skin catalyst (NiPt/Al₂O₃) showed the highest catalytic activity for decarboxylation (62%), while the Ni-skin catalyst had the highest decarbonylation selectivity (58%).