Selective hydrogenation reactions of 5-hydroxymethylfurfural over Cu and Ni catalysts in water: Effect of Cu and Ni combination and the reagent purity

This work studies the catalytic properties of Cu and Ni catalysts, as well as the effect of Cu and Ni combination on the activity and selectivity during the aqueous phase hydrogenation of 5-hydroxymethylfurfural (HMF) in a batch reactor, at 60 °C under 30 bar H2. Catalysts with different Ni/Cu ratios (10 wt%) were synthesized over a high surface area graphite (HSAG). While Ni provides the bimetallic catalyst the capacity for hydrogenation of CO and CC groups, Cu contributes to suppress the hydrogenation of the furan ring, reaching a 99% of selectivity to the partial hydrogenated product, 2,5-di-hydroxymethylfuran (DHMF), over 5Cu5Ni/HSAG. The increase of reaction temperature (180 °C) conduced to the hydrolytic ring-opening and rearrangement of HMF. Under such reaction conditions, monometallic Ni afforded the highest yield towards the hydrogenative rearrangement product, 3-hydroxymethylcyclopentanone (81%). However, Cu and CuNi bimetallic catalysts were less reactive to the ring-rearrangement reaction and showed higher tendency to deactivation, especially when the HMF supplier contain sulfur impurities.