Selective hydrogenation of levulinic acid to γ-valerolactone over copper based bimetallic catalysts derived from metal-organic frameworks

Abstract

The transformation of biomass or feedstocks derived from biomass into fuels or chemicals with added value is an essential step in the process of transitioning to a low-carbon energy system. In this study, metal-organic framework (MOF)-derived non-noble bimetallic catalysts (copper-cobalt [CuCo], copper-nickel [CuNi] and copper-iron [CuFe]) were synthesized and used for selective levulinic acid (LA) hydrogenation to γ-valerolactone (GVL). The results demonstrated that adding the second metal could significantly improve the Cu@C catalytic activity. A 100% yield of γ-valerolactone was obtained by using the CuCo@C catalyst at 220 °C, 10 bar of H2 and a reaction time of 4 h. Advanced characterizations demonstrated that the excellent catalytic activity benefits from the even concentration of both metals on the surface, the abundance of active sites (Lewis and Bronsted) created by the even dispersion of both metals and the accessible surface area and pore volume originated from MOF precursor. The copper-based bimetallic catalysts also showed excellent catalytic durability with no significant decrease in GVL selectivity. Using MOF as a precursor for catalyst preparation can enable high dispersion of active metal sites and prevent their leaching, coking (carbon deposit) or aggregation in the carbon matrix during catalytic testing.