Acidity enhancement through synergy of penta- and tetra-coordinated aluminum species in amorphous silica networks.

ABSTRACT: Amorphous silica-aluminas (ASAs) are widely used in acid-catalyzed C-H activation reactions and biomass conversions in large scale, which can be promoted by increasing the strength of surface Brønsted acid sites (BAS). Here, we demonstrate the first observation on a synergistic effect caused by two neighboring Al centers interacting with the same silanol group in flame-made ASAs with high Al content. The two close Al centers decrease the electron density on the silanol oxygen and thereby enhance its acidity, which is comparable to that of dealuminated zeolites, while ASAs with small or moderate Al contents provide mainly moderate acidity, much lower than that of zeolites. The ASAs with enhanced acidity exhibit outstanding performances in C-H bond activation of benzene and glucose dehydrati

SUBMITTER: Wang Z 

PROVIDER: S-EPMC6957685 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature