Effects of water on the hydrogenation of acetone over Ni/MgAlO catalysts

Abstract

The effect of water on the hydrogenation of acetone to isopropanol (IPA) on the Ni/MgAlO catalyst was studied. It was found that small amount of water added in the acetone promoted the conversion of acetone to IPA, while more H2O added (>5%) significantly decreased the conversion of acetone. Microcalorimetric adsorption results showed that the presence of small amount of pre-adsorbed water (4% coverage) enhanced the adsorption of acetone while inhibited the adsorption of IPA on Ni, which might be the important reasons for the promotion effect of some water on the hydrogenation of acetone to IPA. On the other hand, the heats for the adsorption of H2, acetone and IPA on the Ni/MgAlO were significantly decreased when more water was pre-adsorbed, which might explain the inhibition effect of more water on the hydrogenation of acetone. The results of infrared spectroscopy revealed that the presence of water suppressed the dehydrogenation of adsorbed IPA to acetone and the formation of enolate and mesityl oxide species from adsorbed acetone, which might be the other reasons for the positive effect of water on the hydrogenation of acetone to IPA.