FexNiy/ SiO2-Al2O3 catalyzed hydrodeoxygenation of biorenewable platform molecules

Abstract

A series of FexNiy/SA (SA = SiO2-Al2O3) catalysts were synthesized via solvothermal assisted deposition precipitation synthesis method and explored for low-temperature hydrodeoxygenation (HDO) reaction of methyl oleate into n-alkanes and vegetable oils. A comprehensive study on the effects of increasing iron oxide loading in catalyst samples, i.e., Fe1Ni1/SA, Fe3Ni1/SA, Fe5Ni1/SA and Fe7Ni1/SA, on the crystallographic, morphological, textual and surface chemical behavioural were investigated thoroughly using various spectroscopic techniques. The study disclosed excellent surface area, high acidic strength and reducibility of Fe1Ni1/SA catalyst due to the lowest Fe2+ or FeO species. In contrast, higher iron oxide loading leads to the accumulation of Fe2+ ions on the surface with reduced metal acid centres and diminished surface area. The catalytic conversion as well as C17-C18 selectivity in catalytic HDO was also scrutinised with particular reference to Fe2+/Fe3+ ion ratio. The obtained superior catalytic activity and C18 selectivity of Fe1Ni1/SA catalyst are due to the lowest Fe2+/Fe3+ ion ratio. However, the iron oxide loading increased the Fe2+/Fe3+ ion ratio, which ultimately decreased the catalytic activity. Thus, the role of Fe2+ species in the deactivation of catalyst was discussed in detail to establish conversion and selectivity control in the catalytic HDO pathway.