Liquid-Phase Hydration of Acrylonitrile to Acrylamide over the Manganese Dioxide Catalyst

Article abstract of DOI:10.1246/bcsj.60.453

The liquid phase hydration of acrylonitrile to acrylamide was examined over a manganese dioxide catalyst at 65 deg C.When the catalysts were treated at 110-500 deg C, both the acidity and the reaction activity of the catalysts decreased at temperatures above 110 deg C.The reduction of the solid acidity of heat-treated samples decreased the catalytic activity of the catalysts.It was confirmed that the solid acidity of manganese dioxide was derived from acidic hydroxyl groups on the catalyst surface through their dispersion in water.A good relationship between the number of the surface hydroxyl groups and the catalytic activity of the manganese dioxide was observed ; its hydration ability was depressed by the addition of an aqueous base as a NaOH solution.These result show that the acidic surface hydroxyl group of a manganese dioxide catalyst is the active site of acrylonitrile hydration.The kinetic behavior of both acrylonitrile and water was examined and the reaction rate showed both first and zero orders with respect to the acrylonitrile and water concentration, respectively.The hydration mechanism of acrylonitrile on the manganese dioxide catalyst is discussed.