INFLUENCE OF SURFACE SUPPORT PROPERTIES ON THE LIQUID-PHASE HYDROGENATION OF PROPARGYL ALCOHOLS ON ALPO4-SUPPORTED NICKEL-CATALYSTS

Liquid-phase semihydrogenation of propargyl alcohols (2-propyn-1-ol, 3-butyn-2-ol and 2-methyl-3-butyn-2-ol) has been carried out on nickel catalysts at 20 wt.% supported on three different AlPO4, identical from a chemical point of view, but different in textural and acid-base properties. According to the results, the acid-base nature of the supports, through metal-support interaction effects, plays an important part in determining the specific catalytic activity of supported nickel catalysts. These metal-support interaction effects, as well as the methyl substitution effects on catalytic activity, can be evaluated through several isokinetic parameters obtained due to the existence of a linear correlation between the activation parameters E(a) and In A (obtained from the Arrhenius equation) known as the 'compensation effect'. These isokinetic parameters are also linearly related to the surface density of acid and basic sites as determined by titration with pyridine and cyclohexylamine, acrylic acid and phenol, respectively.