Nano-Au Anchored in Organic Base Group-Grafted Silica Aerogel: A Durable and Robust Catalysts for Green Oxidative Esterification of Furfural

Graphical This work presented a stable and high-efficient synergistic catalytic system based on Au nanoparticle anchored in organic base group-grafted silica aerogel for oxidative esterification of furfural with H 2 O as a by-product, which has excellent resistance to deactivation induced by product adsorption and leaching of the components, and can almost completely convert furfural to alkyl furoate in 7 cycles. Inorganic metal (hydro)oxide supports with appropriate basicity or acid-base properties can promote oxidative esterification of furfural over Au-based catalysts, however, they suffer the problems of easy inactivation induced by the leaching of the components in this water-producing reaction and the shield of catalytic sites by product adsorption. In this work, we report efficient and stable oxidative esterification of furfural over Au nanoparticles anchored in aminopropyl-grafted silica aerogel. The support is insoluble and possesses no strong Lewis acid sites to adsorb oxygen-containing products or intermediates, reducing the probability of catalyst deactivation induced by adsorption. In 7 cycles of reactions, the catalyst maintained the initial activity without any treatments, the yields of alkyl furoate kept above 98 %, and no agglomeration and leaching of Au occurred. Moreover, the roles of Au, alkyl chain, −NH 2 group and Au-activated O species in reactions were clarified, and accordingly, a possible catalytic mechanism involving oxidative dehydrogenation was given.