Bridging and terminal hydroxyl groups of Zr(OH)4 as active sites for the ultraselective transformation of biomass-based alcohols

Abstract

Developing a cost-effective and multi-functional heterogeneous catalyst for various biomass transformations is important in both academic and industrial communities. Dehydration and oxidative dehydrogenation of biomass-based alcohols are fundamental transformations in both academic and industrial settings. However, due to the different catalytic mechanisms, using the same catalyst for regulating the selectivity of two reactions is a great challenge and has not been reported. In this work, we have pioneered the discovery of cheap and commercially available Zr(OH)₄ as a bifunctional heterogeneous catalyst for the selective transformation of biomass platform molecular 1-phenylethanol to acetophenone or styrene without any additives. Control experiments and DFT calculations revealed that the terminal and bridging hydroxyl groups of Zr(OH)₄ are the active sites for catalytic oxidative dehydrogenation and dehydration of 1-phenylethanol, respectively. As far as we know, this is the first report that simultaneously achieves the oxidative dehydrogenation and dehydration of alcohol by the same catalyst. This study proves the unique capabilities of the hydroxyl sites of Zr(OH)₄ and would help to design a multi-functional catalyst for the regulation of reaction selectivity.