Au/Sn-Beta catalyst with metal-Lewis acid cooperative sites steers aerobic oxidation of 5-hydroxymethylfurfural

2,5-Furandicarboxylic acid (FDCA) is a potential substitute of petroleum-based terephthalic acid to manufacture polymer. The selective aerobic oxidation of renewable 5-hydroxymethylfurfural (HMF) to FDCA is a promising and appealing route for establishing sustainable and environmentally friendly chemical process. Au catalysts have exhibited exceptional catalytic performances for this highly anticipated chemical transformation, where the used support intensively impacts the catalytic productivity from the standpoint of metal-support and guest organic-support interactions. Herein, Sn-Beta zeolite was straightforward and rapidly synthesized via structural reconstruction without the auxiliary of any solvents, which was adopted as support for Au catalyst to construct bifunctional catalysts. As for Au/Sn-Beta sample, Lewis acid sites were related to Sn 4+ ions in the zeolite framework, while electronic properties and particle size of Au species were capable of being modulated by Au dosages. In addition, charge transfer from Au species to framework Sn 4+ ions resulted in the formation of Au δ+ species. Au/Sn-Beta catalyst with metal-Lewis acid cooperative active sites showed unique catalytic productivity of FDCA product in the aerobic oxidation of HMF to FDCA, whose catalytic performance was correlated with Lewis acid amounts as well as geometric and electronic effect of Au particle. Reaction mechanism analysis revealed the pathway and concrete step that Lewis acid site functioned. The aim is to provide some guidance for constructing a task-specific multifunctional supported catalyst from the view of support-enhanced effect for the catalytic conversion of biomass resource with multi-functional-groups.