Base-free oxidation of glycerol to glyceric acid over Pt/biochar catalyst

Upgrading the surplus glycerol to access valuable oxygenated-derivatives is of vital importance but confronting the huge challenge of seesaw problem between productivity and selectivity especially in base-free system. We here prepare a series of biochar supported Pt catalysts (Pt/biochar), among which the Pt-supported on Fir biochar (derived from Chinese fir) catalyst (Pt/Fir) exhibits extraordinary activity for glycerol valorization, achieving a remarkable glyceric acid selectivity (86.0 %), exceeding the state-of-the-art benchmarks. At such a high glyceric acid selectivity, glyceric acid yield up to 71.3 % is gained without the use of basic additive under mild conditions (353 K, 0.3 MPa O 2 ), which is comparable to the highest value in base-free system reported to date. Fir biochar features abundant porous structures with the highest surface area and surface defects, and plentiful phenolic and carboxyl groups, which serve as primary sites to anchor Pt. This unique structure facilitates the uniform Pt dispersion and enhances the interaction between Pt and Fir biochar. Both metallic Pt⁰ and oxidized Ptⁿ⁺ species coexist on Pt/Fir catalyst, synergistically contributing to glyceric acid production. Specifically, Pt⁰ in conjunction with oxygen vacancies on the support activates molecular oxygen (O₂), while Ptⁿ⁺ preferentially adsorbs and activates glycerol feedstock. Pt/Fir showcases high tolerance in acidic solution, thus effectively mitigating metal leaching and exhibiting extraordinary recyclability. The in-depth insights on the structure and properties of biochar derived from diverse biomass feedstock will give foundational guidelines to design the sustainable heterogeneous catalyst in glycerol valorization. • Chinese Fir serves as the optimal feedstock to prepare Pt/Fir (biochar) catalyst. • Pt/Fir affords glyceric acid with remarkable selectivity in base-free system. • The unique structures of Fir enhance Pt dispersion and the interaction with Pt. • Both Pt⁰ and oxidized Ptⁿ⁺ on Pt/Fir contribute to glyceric acid production.