Green Catalytic Synthesis of 5‐hydroxymethyl‐2‐furancarboxylic Acid in a Gram Scale Over Schiff Base Polymer Supported Silver‐Nanoparticle Catalysts

Abstract Here, a series of Schiff‐base porous organic polymer‐supported silver nanoparticles, Ag 0 NPs@PPTA ‐x, were prepared with a two‐step ion coordination/hydrogen reduction. The resulting composite Ag 0 NPs@PPTA ‐9.08 shows excellent catalytic performance for HMF oxidation to HMFCA, and an impressive HMFCA yield of 99.3% was achieved under optimal conditions (NaOH 1.5 eq, 50 mL min −1 air flow, 20 °C, 6 h). Analysis techniques such as ICP‐OES, XRD, TEM, SEM, N 2 adsorption‐desorption, and XPS were employed to characterize the structure and properties of Ag 0 NPs@PPTA ‐x . The results indicate that the coordination of the nitrogen atom is the key factor for the higher activity and stability of Ag 0 NPs@PPTA ‐9.08 . The results of leaching and reusing tests, as well as structural characterization (XRD, SEM, and FT–IR), show that the Ag 0 NPs@PPTA ‐9.08 have good stability and robust structure. Furthermore, a gram‐scale oxidation of HMF indicates this catalytic system can be readily scaled up to an industrial level. Finally, the results of other aldehydes oxidation over Ag 0 NPs@PPTA ‐9.08 indicate the good substrate adaptability of the Ag 0 NPs@PPTA ‐9.08 . This work provides a new method for stabilizing nano‐silver catalysts and opens up a simple avenue to the selective oxidation of aldehydes that easily scaled up.