Gas-phase hydrogenation of furfural over Cu/CeO2 catalysts

Abstract

Cu-CeO2-x catalysts, with a Cu/Ce molar ratio between 0.2 and 6.0, have been synthesized by coprecipitation, calcination and subsequent reduction. These samples have been characterized by X-ray diffraction, H2 temperature-programmed reduction, N2O titration, N2 adsorption-desorption at −196°C and X-ray photoelectronic spectroscopy, among other techniques. They exhibit small average particle sizes, high dispersion of copper species, porosity and high metal surface. Their catalytic behavior was evaluated in the gas-phase hydrogenation of furfural (FUR), evidencing high activity and stability due to the strong interaction Cu-CeO2. The highest conversion was attained for catalysts with higher copper content, which display higher metal surface, with a value of 83% after 5h of time-on-stream (TOS) for the Cu-CeO2-6 catalyst, at 190°C, by using a H2:FUR molar ratio of 11.5 and a WHSV of 1.5h−1. In all cases, only furfuryl alcohol (FOL) and 2-methylfuran (MF) were obtained as reaction products, being majority MF for shorter TOS and FOL for longer, which can be explained by the deactivation of the highly hydrogenating sites by carbonaceous deposits and the oxidation of the active phase by water generated in the dehydration process to obtain MF.