抄録
The synthesis of ethyl isoamyl ketone from sec-butyl alcohol was studied over various catalysts composed of noble metals and metal oxides. The reaction was carried out by a flow method in vapour phase under atmospheric pressure. Weak solid acids or bases such as ZnO, ThO2, TiO2 and ZrO2 were effective as metal oxide components of the catalysts, but strong acids or bases were not. Pt-ZrO2 was found to be the most active and selective for the reaction. Moreover, the activity of Pt-ZrO2 did not decline during 110 hours run. Experimental results on Pt-ZrO2 were elucidated by the following mechanism. Two molecules of methyl ethyl ketone formed from sec-butyl alcohol react to form 5-hydroxy-5-methylhepta-3-one which is dehydrated and then hydrogenated to form ethyl isoamyl ketone. The rate determining step seemed to be the condensation reaction of methyl ethyl ketone. The acid-base concerted mechanism was proposed for the condensation reaction over Pt-ZrO2, on the basis of the fact that the introduction of acidic and basic materials to the reaction system caused marked decrease of the activity.
