Mesoporous mixed CuCo oxides as robust catalysts for liquid-phase furfural hydrogenation

Abstract

A series of highly ordered mesoporous CuCo oxide catalysts with a controlled composition are successfully synthesized by nanocasting from mesoporous silica, KIT-6 template. Liquid-phase furfural (FAL) hydrogenation is carried out to find the optimal composition of the CuCo oxide catalysts to achieve the best catalytic performance. As-prepared mesoporous mixed CuCo oxides exhibit a high surface area (60‒135 m2 g−1) and a well-defined ordered mesostructure with homogenous dispersion of Cu and Co. Among various compositions of CuxCoy oxides (x = 1–9) studied, the Cu1Co5 oxide catalyst shows the highest conversion in the hydrogenation of FAL, which is superior to those achieved with mesoporous monometallic oxides, CuO and Co3O4. While 2-methylfuran is produced from furfuryl alcohol via aldehyde hydrogenation and subsequent hydrogenolysis, the formation of 2-methylfuran increased with a decrease in the Cu/Co ratio of the CuCo oxide catalyst. The mixed CuCo oxide catalyst is readily reduced under the reaction environment to produce metallic CuCo as the active species. The synergistic interactions between Cu and Co in the mixed CuCo oxide catalysts play an important role in the outstanding catalytic performance for FAL hydrogenation, which could not be achieved with either of the monometallic catalysts or their physical mixtures. The excellent stability and recyclability of mesoporous mixed CuCo oxide catalysts as well as the exceptionally high activity, surpassing those of the monometallic oxides, render them promising as a low-cost and efficient catalyst for the industrial upgrading of biomass-derived FAL.