Acetic acid hydrogenation catalysts based on platinum and tin supported alumina were modified by adding potassium with different loading amounts and various impregnation sequences. The modification of K caused red shift of CO adsorbed peak, decreased Pt 4d(5/2) binding energy and enhanced carbonyl group adsorption, which can promote the selectivity to ethanol. The block effect of K on acid sites was able to restrain side reaction. Further co-impregnation of Pt and Sn to K-doped support led to the poor dispersion of Pt active sites bringing about the low catalytic activity. While catalysts prepared by impregnating PtSn into K-doped alumina were not proper for acetic acid hydrogenation, but adding 0.5 wt.%K into PtSn catalyst enhanced both selectivity of ethanol from 37% to 64% and conversion of acetic acid from 88% to 93%. Further increasing potassium loading caused little change on catalytic behavior. (C) 2015 Elsevier B.V. All rights reserved.