Switching between Hydrogenative Hydrogenolysis and Rearrangement of Furfurals via Hydrogen Pressure-Driven Acid–Base Transformation over Br–Pt Pairs

Controlled hydrogenative hydrogenolysis and rearrangement of furfurals to polyols and cyclopentanones are critical for upgrading biomass to fine chemicals, but are challenging owing to the easy overhydrogenation route. Herein, bromine (Br)-modified platinum (Pt) nanoparticles were fabricated and showed unusual H2 pressure-governed catalytic properties for furfural (FFA), yielding 1,2-pentanediol (PDL) and cyclopentanone as the main products at low (1.0 MPa) and high (6.0 MPa) H2 pressures, respectively. The catalytic mechanism shows that the Br–Pt pairs not only accelerate carbonyl (C═O) hydrogenation and furan semihydrogenation steps of FFA but also act as basic sites (Brδ−) to promote the hydrogenolysis step of the dihydrofuran alcohol intermediate in PDL synthesis. However, a high H2 pressure triggers hydrogen spillover and causes the formation of H+–Br–Pt–H– pairs, which can act as nontraditional sites for the selective C═O hydrogenation step of FFA and provide Brønsted acidic sites (H+) for the rearrangement step of furan alcohol, thereby yielding cyclopentanone. Furthermore, the H2 pressure-controlled reaction route exhibited generality for other furfurals (e.g., 5-methyl furfural and 5-hydroxymethyl furfural). Herein, we present an interesting reaction-route regulation by H2 pressure-driven transformation of acid/base properties over Br-modified Pt nanoparticles, which was previously unattainable in conventional catalysis.