METAL-SUPPORT INTERACTION EFFECTS IN THE LIQUID-PHASE SELECTIVE HYDROGENATION OF 1,4-BUTYNEDIOL WITH NICKEL-CATALYSTS SUPPORTED ON ALPO4 AND ON OTHER CONVENTIONAL NON-REDUCIBLE COMPOUNDS

The liquid-phase selective hydrogenation of 1,4-butynediol has been ou t on nickel catalysts at 20 wt.-% supported on different AlPO4, AlPO4- Al2O3 and AlPO4-SiO2 systems. Furthermore, some conventional non-reduc ible compounds, such as SiO2, Al2O3, active carbon or a natural sepiol ite were also used as supports. In addition, the effects of nickel loa ding and Ni-Cu alloying were studied using carbon as the metal support . The relative adsorption constants, K(T,D), were also obtained from t he relative reactivities, R(T,D), obtained in the consecutive hydrogen ation process and the corresponding individual hydrogenation rates of 1,4-butynediol and 1,4-butenediol. These values were used to follow th e changes in the electronic structure of supported nickel crystallites . Besides, structural defects of supported-nickel crystallites such as 'twin faults', 'stacking faults' and 'microstrains', were determined by X-ray diffraction line broadening analysis. These parameters were u sed for measuring the participation of geometric support effects in th e catalytic activity of supported nickel catalysts. TEM measurements c oupled with digital image processing were also used to measure nickel particle sizes. Results obtained in the correlation between kinetic da ta and structural defects in supported-nickel crystallites as well as with textural and acid-basic properties of the supports indicated that electronic and geometric effects were simultaneously developed throug hout metal-support interactions.