Effect of the reduction temperature on the selectivity of the high temperature reaction of acetone and hydrogen over alumina and titania supported nickel and cobalt catalysts

The high-temperature acetone hydrogenation at atmospheric pressure over alumina and titania-supported nickel and cobalt catalysts has been studied. The results obtained during characterization have shown that the preparation steps produced a significant metal—support interaction in the alumina-supported precursors. On the other hand, the high-temperature (500°C) reduced titania-supported catalysts showed catalytic properties which resemble in some aspects those ascribed to the SMSI state. An interesting effect of the previous H₂ reduction temperature on the acetone hydrogenation selectivity has been found. 2-Propanol and methyl isobutyl ketone (MIBK) were the main reaction products. The MIBK selectivity of the alumina-supported catalysts decreased as the temperature of reduction was increased. However, whereas the low-temperature (300°C) reduced titania-supported catalysts did not give any MIBK, a remarkable activity to this product was developed when the temperature of reduction was increased to 500°C. The effect of the temperature of reduction on selectivity has been tentatively explained according to a general model which relates the activation of the carbonyl functional group with specific sites created at the metal—support interface under conditions favourable to the establishment of significant metal—support interactions.