Vapor-phase catalytic dehydration of 2,3-butanediol to 3-buten-2-ol over ZrO2 modified with alkaline earth metal oxides

Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) to produce 3-buten-2-ol (3B2OL) was investigated over several monoclinic ZrO2 (m-ZrO2) catalysts modified with alkaline earth metal oxides (MOs), such as SrO, BaO, and MgO, to compare with the previously reported CaO/m-ZrO2. It was found that these modifiers enhanced the 3B2OL formation to the same level as CaO did by loading an appropriate MO content. Among all the tested catalysts, the BaO/m-ZrO2 calcined at 800 degrees C with a low BaO content (molar ratio of BaO/ZrO2 = 0.0452) shows the highest 2,3-BDO conversion (72.4%) and 3B2OL selectivity (74.4%) in the initial stage of 5 hat 350 degrees C. In order to characterize those catalysts, their catalytic activities, crystal structures, and basic properties were studied in detail. In X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) experiment, it was elucidated that highly dispersed M-O-Zr (M = Ca, Sr, and Ba) hetero-linkages were formed on the surface by loading these MOs onto m-ZrO2 with an appropriate content and then calcining at 800 degrees C. It can be concluded that the M-O-Zr hetero-linkages generate the proper base-acid balance for the efficient formation of 3B2OL from 2,3-BDO. (C) 2016 Elsevier B.V. All rights reserved.