Brønsted acid sites formation through penta-coordinated aluminum species on alumina-boria for phenylglyoxal conversion

Recently, Penta-coordinated Al (AlV) have attracted large attention and is promising for tailoring catalysts with the capability to form new BAS in specific mixed oxide. In this study, amorphous alumina-boria materials with enriched surface AlV were prepared as platforms for the formation of potential new BAS. With the aid of solid-state NMR, interacting species of AlV with three-coordinated boron have been identified in the highly distorted local structure with BAS forming potential (AlV-OH···BIII). The catalytic activity of the AlV-BAS has been tested by the phenylglyoxal conversion, where the functionality of AlV-BAS has been further verified by the in situ 1H NMR. Herein, the ssNMR observation demonstrates the first experimental visualization of a new type AlV-BAS in non-silica alumina materials present with predominance. The AlV-BAS is promising to serve as one new state-of-the-art strategy to improve acid catalytic performance in varied mixed oxides.