Hierarchical porous bowl-like nitrogen-doped carbon supported bimetallic AuPd nanoparticles as nanoreactors for high efficient catalytic oxidation of HMF to FDCA

Efficient nanoreactors for the catalytic oxidation of the key platform compound HMF to the high value-added chemical FDCA are highly desirable in the field of biomass transformation. Herein, hierarchical porous bowl-like nitrogen-doped carbon supported AuPd bimetallic (AuPd/pBN x C) nanoreactors were synthesized by the following steps: precipitation polymerization, carbonization, SiO 2 sphere removal, and sol curing. By changing the amount of nitrogen doping and removing the template, AuPd/pBN x C nanoreactors with a hierarchical porous structure and adjustable basicity were prepared. The alkaline sites of N x C carriers provided anchoring sites for metals and had a certain adsorption affinity for HMF and its intermediates. Theoretical calculations and adsorption experiments indicated that the doped nitrogen significantly enhanced the combining capacity between the HMF molecule and nanoreactors. The nanoreactor was used for the tandem oxidation of HMF to FDCA in water, and the highest FDCA yield of 97.6% could be obtained under optimum reaction conditions. The reaction process was evaluated by kinetics calculations, and the oxidation of FFCA to FDCA was confirmed as the rate-determining step. The regeneration experiments showed that the AuPd/pBN x C nanoreactors could be recycled and reused at least five times without an obvious loss in catalytic activity.