Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) was investigated over several metal oxides loaded on well-crystallized monoclinic ZrO2. In the dehydration of 2,3-BDO, unsaturated alcohol, i.e. 3-buten-2-ol (3B2OL), was preferentially produced together with major by-products such as butanone and 3-hydroxy-2-butanone over ZrO2-based catalysts. The selectivity to 3B2OL over monoclinic ZrO2 was greatly enhanced by the alkaline-earth oxides such as CaO, SrO, and BaO. At a CaO loading of 3 wt% on the monoclinic ZrO2, a Ca-O-Zr hetero-linkage was formed to generate new basic sites, and the selectivity to 3B2OL exceeded 76% at 350 degrees C. Poisoning experiments using CO2 and NH3 strongly suggest that the formation of 3B2OL from 2,3-BDO proceeds over base-acid concerted sites. (c) 2014 Elsevier B.V. All rights reserved.