Vapor-phase selective dehydration of 1,4-butanediol to 3-buten-1-ol over ZrO2 catalysts modified with alkaline earth metal oxides

Modified ZrO2 catalysts were prepared by doping with alkaline earth metal oxides (CaO, SrO, or BaO) in a wet impregnation method. The catalysts were characterized by N-2 physisorption, X-ray diffraction, and temperature-programmed desorption (TPD) with NH3 and CO2. Their catalytic performance in the vapor-phase selective dehydration of 1,4-butanediol (BDO) to 3-buten-1-ol (BTO) was investigated. The results showed that the alkaline earth metal can change the acid-base properties on the catalyst surface and thus affect BDO conversion and BTO product selectivity. For ZrO2 catalyst modified by CaO, Ca2+ entered the ZrO2 crystal lattice and formed Ca-O-Zr hetero-linkages. These allowed the CaO/ZrO2 catalyst to maintain a high acid density and generate a large number of basic sites when compared with unmodified ZrO2. In contrast, SrO and BaO reacted with ZrO2 to generate the corresponding zirconates, which resulted in decreased acid density on the catalyst surface. Of the catalysts tested, CaO/ZrO2 showed the best catalytic performance. The highest yield of BTO was 60.5% and was achieved at 350 degrees C over CaO/ZrO2 catalyst. The key point for highly selective dehydration of BDO to BTO resided in the synergistic effect between acid and base sites on the catalyst surface. (c) 2013, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.