Ethanol condensation to butanol and higher alcohols over nickel and cobalt decorated Ce-Al mixed oxide catalysts

Abstract

Anew series of bimetallic Ni-Co catalysts, prepared by step wise substitution of Ni by Co, in mono metallic Ni (8%)/ CeO2 -Al2O3,withthe compositions of 6%Ni-2%Co, 4%Ni-4%Co, 2.5%Ni-5.5% Co and 8% Co, have been evaluated for conversion of ethanol to butanol and higher alcohols according to Guerbet alcohol chemistry.XRD, TPR and XPS studies reveal the formation of Ni-Co alloys at specific bimetallic compositions. Maximum reducibility is observed for the composition 4%Ni-4%Co,which also displays maximum ethanol conversion (55.1%) with C4+ alcohols selectivity of 50.2%, which are higher than those realized for mono metallic Ni and Co catalysts. Ni-Co alloys in bimetallic catalysts promote the crucial ethanol dehydrogenation and C4 and C4+ aldehydes hydrogenation steps in the Guerbet process, there by increasing ethanol conversion and C4+ alcohol selectivity. Selection of bimetallic catalysts with specific compositions seems to be one of strategies to improve ethanol conversion and higher alcohols selectivity.