Hydrogenation of furfural at the dynamic Cu surface of CuOCeO2/Al2O3 in a vapor phase packed bed reactor

The hydrogenation of furfural to furfuryl alcohol over a CuOCeO2/gamma-Al2O3 catalyst in a flow reactor is reported. The catalyst was prepared by the wet impregnation of Cu onto a CeO2/gamma-Al2O3 precursor. The calcined catalyst was then treated with HNO3 to remove surface CuO resulting in a mixed CuCe oxide supported on gamma-Al2O3. The catalyst was characterized by BET surface measurements, powder XRD, EDX, XPS, and H-2-TPR. Reduction of the catalyst results in migration of Cu2O to the surface of the solid solution. The CeO2 facilitates the reduction of the Cu which in turn leads to increased activated hydrogen being available at the reaction temperature. Furfural hydrogenation was carried out in a downflow reactor at 175 degrees C under hydrogen pressures ranging from 1 to 10 bar. Selectivity to furfuryl alcohol and time on stream before loss of activity due to coke formation were greater at higher pressure. Coke formation was greater at higher furfural flow rates indicating a competition exists between hydrogenation and coke formation. The side products that were measured included 2-methylfuran and difurfuryl ether. The kinetics of the reduction of the Cu sites are also described and found to contribute to catalyst activity. Comparison to commercial copper chromite and 5 wt%Cu/Al2O3 were made to assess practical application of this catalyst. Published by Elsevier B.V.