Selective dehydration of 2,3-butanediol to 3-buten-2-ol over ZrO2 modified with CaO

• Vapor-phase catalytic dehydration of 2,3-butanediol was investigated.
• 3-Buten-2-ol was preferentially produced over CaO/ZrO2 catalysts.
• The catalytic active sites were poisoned by both CO2 and NH3 gases over the catalyst.
• The formation of 3B2OL from 2,3-BDO proceeds over base–acid concerted sites.
• The highest selectivity to 3-buten-2-ol exceeds 76% at 350 °C.

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 °C. Poisoning experiments using CO2 and NH3 strongly suggest that the formation of 3B2OL from 2,3-BDO proceeds over base–acid concerted sites.

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