Abstract
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•Over physically mixed CuO-Pd/C furfural hydrogenation was performed with formic acid.•CuO firstly dissolved into Cu2+ by formic acid, then Cu2+ was reduced by the Pd-H.•Pd promoted the furfural conversion and Cu improved the furfuryl alcohol selectivity.•Cu-Pd alloys functioned well in this reaction with 98.1% furfuryl alcohol yield.•In-situ prepared Cu-Pd/C exhibited an excellent recycle stability.
Catalytic transfer hydrogenation (CTH) of bio-derived furfural (FF) to furfuryl alcohol (FFA) was performed using the physically mixed CuO-Pd/C as catalyst and formic acid (FA) as hydrogen donor. The evolution investigation of Cu showed the precursor CuO firstly dissolved into Cu2+ by FA and then formed coordination polymer-copper(II), which uniformly dispersed in reaction solution of 1, 4-dioxane. Subsequently the Cu2+ was in-situ reduced and Cu-Pd alloys formed simultaneously. The in-situ prepared nano Cu-Pd/C catalyst exhibited the best performance with a complete FF conversion and FFA selectivity of 98.1%. Reaction conditions test suggested that the FFA selectivity was greatly dependent on the Cu content. The underlying mechanism revealed that the Pd in Cu-Pd alloys mainly promoted the FF conversion by enhancing hydrogen adsorption, while the nano Cu for increasing FFA selectivity; the Cu-Pd alloys functioned in synergistic way. Leaching and recycling tests demonstrated an excellent stability of the Cu-Pd/C catalyst.