Highly Efficient Dehydrogenation of 2,3-Butanediol Induced by Metal–Support Interface over Cu-SiO<sub>2</sub> Catalysts
Enxian Yuan, Ping Ni, Ju Xie, Panming Jian, Xu Hou
Abstract
In the present work, Cu–SiO2 catalysts were synthesized by the modified one-pot hydrothermal strategy and employed in the anaerobic dehydrogenation of 2,3-butanediol to clarify the specific dehydrogenation mechanism of diols. Characterization results testified that the properties of −Si–O–Cu–O–Si– structures (CuO-like phase) formed in Cu–SiO2 catalysts can be regulated by precisely tuning the copper loading and synthetic solution alkalinity. The superior catalytic performance with 76.0% conversion of 2,3-butanediol and 94.5% selectivity toward acetoin was achieved over the resulting 20Cu–SiO2-10.5 catalyst. Both experimental and DFT studies demonstrated that the dehydrogenation performance of Cu–SiO2 catalysts originated from the metal–support interface via the synergic catalysis of the interfacial CuO-like phase and Cu0 sites. The CuO-like phase promotes the cleavage of the −O–H bond in 2,3-butanediol by interacting with the Cu2+–O2– pair, and subsequently the other H atom is removed from the α-C–H bond in the generated alkoxy intermediate on neighboring Cu0 sites. Meanwhile, 2,3-butanediol follows the reaction pathway of the dehydrogenation of two −OH groups on the surface of Cu particles, and the generated dialkoxy intermediate strongly adsorbs on Cu0 sites, leading to the deactivation of Cu–SiO2 catalysts as well as the catalytic inertness of impregnated Cu catalysts only having Cu0 sites.