Published on Applied Catalysis B: Environmental (7 May 2022)

Author(s): Guohan Sun, Molly Meng-Jung Li, Keizo Nakagawa, Guangchao Li, Tai-Sing Wu, Yung-KangPeng

Abstract

H₂O₂ has been widely used as a green oxidant in many heterogeneous reactions. However, its disproportionation accelerated by either Brønsted acid (BA) or redox metal sites often results in low H₂O₂ utilization. Given this, metals less able to redox have been used because the formation of surface metal-peroxo species exhibits a certain degree of selectivity towards substrates. However, those catalysts often bear BA sites on their surface for charge balance, making it imperative to study H₂O₂ activation pathway in the presence of both sites. Herein, layered HNb₃O₈ with structurally preserved BA sites was used for this purpose. We found that the exposure of Nb sites via bulk-to-nano regulation of this material hinders H₂O₂ disproportionation promoted by BA sites. Among various Nb-peroxo species, its bidentate configuration formed on highly distorted NbO_x was found to provide the best reactivity in alkene epoxidation with a near stoichiometric H₂O₂ utilization.

Read more: https://www.sciencedirect.com/science/article/pii/S0926337322004027