Biodiesel production from hempseed oil using alkaline earth metal oxides supporting copper oxide as bi-functional catalysts for transesterification and selective hydrogenation

Abstract

Alkaline earth metal oxides supporting copper oxide (Cu/AMO) were used as bi-functional catalysts for transesterification and selective hydrogenation to produce biodiesel from highly unsaturated hempseed oil. Cu/AMO catalysts were characterized by XRD, SEM, N2 adsorption, CO2-TPD, H2-TPR, and XPS to reveal the crystal structure, morphology, texture properties, basicity, reducibility, and surface chemical states. The bi-functional catalysts formed alkaline earth metal cuprates and showed strong basic strengths. Cu/SrO catalyst presented much surface copper species, which were reduced to metallic copper after reactions. The effect of the molar ratio of methanol to oil, copper oxide content, hydrogen pressure, and reaction temperature on the catalytic performance was further investigated. Cu/SrO catalyst showed superior catalytic activity for transesterification and selective hydrogenation. Catalytic activity for transesterification is strongly dependant on basic strength and the amount of basic sites of the bi-functional catalysts. The amount of reduced surface copper species of Cu/SrO catalysts made a large contribution to catalytic activity for selective hydrogenation.