Liquid phase selective hydrogenation of furfural on Raney nickel modified by impregnation of salts of heteropolyacids Original Research Article

In this paper, liquid phase selective hydrogenation of furfural on Raney nickel which has been modified by impregnation of salts (including alkali metals, alkaline earth metals, and transition metals) of heteropolyacids (HPAs) having Keggin type structure was studied. Effects of reaction conditions on catalytic activity and selectivity were examined. It has been found that all Raney nickel catalysts modified with salts of HPAs show higher catalytic activity and selectivity than unmodified Raney nickel catalysts; 12-molybdophosphates give the best results among the modifiers. As far as the effect of competitive cations on catalytic properties is concerned, transition metals are better than both alkali metals and alkaline earth metals. Among the transition metal salts, Cu salt is superb in performance. A Raney nickel catalyst on which 7.1% Cu3/2PMo12O40 has been deposited, under reaction conditions of temperature 353 K, hydrogen pressure 2.0 MPa, amount of catalyst 0.5 g, volume of reactant 10 ml and reaction time 1 h, gave a conversion of furfural and selectivity for furfuryl alcohol of as high as 98.1% and 98.5%, respectively. In this work, the salt of HPA only plays the role of a modifying agent rather than acting as a catalyst. This can be inferred from the experimental evidence that salts of HPAs deposited on active carbon showed no catalytic activity in selective hydrogenation of furfural under similar conditions.