Selective hydrogenation of D-mannose to D-mannitol using NiO-modified TiO2 (NiO-TiO2) supported ruthenium catalyst

NiO-modified TiO2 (NiO-TiO2) supported ruthenium catalyst Ru/(NiO-TiO2) is prepared by simple impregnation method and characterized by using energy dispersive X-ray analysis (EDX/EDS), temperature-programmed reduction (TPR), inductively coupled plasma (ICP) mass spectrometry, transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and CO chemisorption. The catalyst Ru/(NiO-TiO2) is evaluated in D-mannose hydrogenation and hydrogenation experiments to produce a selective product D-mannitol were carried out batch wise in a three-phase laboratory scale reactor. A tentative mechanism for reduction of D-mannose is presented. The kinetics of D-mannose hydrogenation to D-mannitol using catalyst Ru/(NiO-TiO2) was studied. The kinetic data were modeled by zero, first and second-order reaction equations. A set of four experiments was also carried out to test the deactivation of the catalyst. For affording maximum D-mannose conversion, yield and selectivity to D-mannitol, the reaction conditions are optimized. (C) 2012 Elsevier B.V. All rights reserved.