Influence of surface Lewis acid sites for the selective hydrogenation of levulinic acid to γ-valerolactone over Ni–Cu–Al mixed oxide catalyst

Abstract

Al2O3 interacted Cu–Ni bimetallic catalysts derived from incorporation of Cu into Ni–Al hydrotalcite were found to be efficient in the selective transformation of levulinic acid (LA) to γ-valerolactone (GVL). The promotional effect of Cu on Ni hydrogenation activity was explained due to an increased ease of NiO reduction and also enhanced surface Lewis acid sites measured by DRIFT spectroscopy. An optimum composition of Ni–Cu–Al catalyst with a mole ratio of 44:22:33 (NCA-423) exhibited a higher Ni metal surface area which demonstrated superior performance in the hydrogenation of LA to GVL with a productivity of 1.68 kgGVL kg cat −1 h−1. The physicochemical properties of Ni–Cu–Al catalysts were rationalized by XRD, H2-TPR, XPS, EPR, BET surface area, H2 chemisorption and pyridine adsorbed IR spectroscopy.