Hydrogenation of ethyl phenylacetate to 2-phenylethanol by ruthenium/tin/alumina catalysts elimination of need for high temperature activation of the catalysts with hydrogen; optimum oxidation state of tin

Abstract

The redox behavior of ruthenium and tin oxides unsupported and supported on alumina was investigated using thermogravimetric analysis. Ruthenium oxide was easily reduced to the metal in a hydrogen stream at room temperature, irrespective of the presence of any alumina support. SnO supported on alumina was not reduced to Sn metal in a hydrogen stream at temperatures below 513 K, even in the presence of ruthenium. Ruthenium/tin/alumina catalysts with different oxidation states of ruthenium and tin were prepared and tested in the hydrogenation of ethyl phenylacetate to 2-phenylethanol. It was proved that the catalyst does not always need to be activated in a hydrogen stream at a high temperature. The ruthenium component of the catalyst transforms easily to zero oxidation state. However, tin retains its original oxidation state. The oxidation state of tin determines the activity of the catalyst in the hydrogenation of ethyl phenylacetate to 2-phenylethanol. The Sn(II) is found to be the optimum oxidation state for the formation of 2-phenylethanol.