The Bifunctional Nature of Nickel-Magnesia Catalyst in the Conversion of Acetone to Isobutyl Methyl Ketone

Abstract

The titled conversion has been studied over several nickel-supported catalysts. The reaction was carried out at a temperature range of 150-250°C under atmospheric pressure in a flow reactor.
Magnesia containing about 10-20 wt % of the metal was found to be the most active and selective catalyst for this conversion: silica-magnesia, silica-alumina, r-alumina and titania were inferior to magnesia. When a nickel-magnesia catalyst system was used, the major byproducts were mesityl oxide [ 1 ] diisobutyl ketone 1 2 and 2-propanol [ 3 ] depending upon the metal content of the catalyst: Decrease in [ 1 ]and increase in [ 2 ] and [ 3 ] were observed with an increase of nickel content.
Introduction of small amounts of propionic acid to the feed stream suppressed markedly the activity of the catalyst. Isobutyl methyl ketone was produced when magnesia layer followed by nickel-silica gel layer was used, or when a mechanical mixture of two layers was used as catalyst.
This ketone was not produced through the reaction of acetone with [ 3 ]. Therefore, the titled conversion over nickel-magnesia catalyst is suggested to proceed through the base-catalyzed condensation of acetone to I followed by the hydrogenation of the latter.