Gas-phase hydrogenation of furfural to furfuryl alcohol over Cu/ZnO catalysts

•CuZnO catalysts are active in hydrogenation of furfural to furfuryl alcohol.•The Cu–ZnO interaction is higher for lower copper loading.•Long term stability is improved in comparison with copper chromite.•Selectivity to furfuryl alcohol is higher at low H2 feed rates.

A series of Cu/ZnO catalysts (Cu:Zn molar ratio = 0.2–6.0), prepared by coprecipitation and subsequent calcination and reduction, has been characterized and evaluated in the gas-phase hydrogenation of furfural (FUR). All catalysts exhibit high stability, with conversion values higher than 55 mol% after 5 h of time-on-stream (TOS) at 463 K with a H2:FUR molar ratio of 11.5 and a WHSV of 1.5 h−1. The best catalytic performance is found for the catalyst with the lowest copper loading, which maintains a conversion of 93 mol% after 5 h of TOS, with a selectivity of 82 mol% towards furfuryl alcohol. After 24 h of TOS, this catalyst still shows a furfuryl alcohol yield of 60 mol%. The strong metal-support interactions in the catalysts with lower copper contents explain their higher stabilities. In all cases, the carbon percentages in the used catalysts are lower than 1.5%, thus indicating that carbonaceous deposits could be the cause of the slight deactivation of Cu/ZnO catalysts, together with metal sintering in catalysts with higher copper contents.

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