Superior catalytic performance of Ce1−xBixO2−δ solid solution and Au/Ce1−xBixO2−δ for 5-hydroxymethylfurfural conversion in alkaline aqueous solution

Porous Bi-doped ceria (Ce1−xBixO2−δ solid solution) was prepared by the easy citrate method and then used as a supporting material for Au nanoparticles (NPs) obtained by deposition–precipitation. In the presence of O2, Ce1−xBixO2−δ (0.08 ≤ x ≤ 0.5) efficiently catalyzed the conversion of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HFCA) and 2,5-bishydroxymethylfuran (BHMF) in alkaline aqueous solution without degradation of HMF. The excellent catalytic activity was attributed to the oxygen activation and hydride transfer enhanced by Bi doping and the large amount of oxygen vacancies. After Au NPs were supported on Ce1−xBixO2−δ (x ≤ 0.2), the presence of Auδ+ facilitated the activation of the C–H bond in the hydroxymethyl group and then the production of 2,5-furandicarboxylic acid (FDCA) as an end product, inhibiting the generation of BHMF.