Catalytic dehydration of 1,3-butanediol over oxygen-defected fluorite Yb2Zr2O7

Abstract

Vapor-phase dehydration of 1,3-butanediol was performed over Yb2O3-ZrO2 catalysts in an ambient nitrogen atmosphere. Catalysts were prepared by a hydrothermal (HT) method as well as a coprecipitation method. The Yb2O3-ZrO2 sample prepared by HT was confirmed to be crystallites of oxygen-defected type cubic Yb2Zr2O7, while the as-prepared coprecipitation sample was amorphous. The HT samples had high specific surface areas as ca. 40 m2 g−1 even after calcined at temperatures higher than 800 °C, whereas the coprecipitation samples without HT was readily sintered at the high temperatures. The best catalytic performance was obtained over HT Yb2O3-ZrO2 catalyst calcined at 900 °C: the total selectivity to unsaturated alcohols was higher than 95% at a 1,3-butanediol conversion of 82% at 325 °C. The structure of active sites and the reaction mechanism of the dehydration of 1,3-butanediol were discussed. We proposed that an oxygen defect site on the stable (111) face of cubic Yb2Zr2O7 would provide an active site, and that Zr4+, Yb3+, and O2- exposed on the defect could coordinate with a 1,3-butanediol molecule to form a tridentate coordination structure, which possibly initiate the dehydration to produce unsaturated alcohols through a base-acid concerted mechanism.