Selective Hydrogenolysis of α-C–O Bond in Biomass-Derived 2-Furancarboxylic Acid to 5-Hydroxyvaleric Acid on Supported Pt Catalysts at Near-Ambient Temperature

Hydrogenolysis of the α-C–O bond in abundantly available biomass-based furfural and its derivatives provides a viable route for sustainable synthesis of valuable C5 compounds, particularly with two terminal oxygen-containing functional groups. However, efficient cleavage of this bond under mild conditions still remains a crucial challenge, primarily because of the competing cleavage of the δ-C–O bond and hydrogenation of furan ring. Here, we report that supported Pt catalysts were extremely active for the selective α-C–O cleavage in 2-furancarboxylic acid (FCA) hydrogenolysis to synthesize 5-hydroxyvaleric acid (5-HVA), affording a high yield (∼78%) on Pt/SiO2 with a Pt particle size of 4.2 nm at an unprecedentedly low temperature of 313 K. In this reaction, the turnover rate and 5-HVA selectivity sensitively depend on the size of the Pt nanoparticles and the underlying support, as a consequence of their effects on the exposed Pt surfaces. Combined reaction kinetic, infrared spectroscopic, and theoretical assessments reveal that while the exposed high-index Pt surfaces (containing higher fraction of step sites) facilitate the kinetically relevant addition of the first H atom to the unsaturated C atom in furan ring and thus the hydrogenolysis activity, the low-index surfaces (containing higher fraction of terrace sites), together with the electron-withdrawing effect of the carboxylic substituent in FCA, favorably stabilize the dangling C2 atom in the transition states of α-C–O cleavage and lower their activation barriers, leading to the observed high 5-HVA selectivity. Such pivotal roles of the intrinsic properties of metal surfaces and substituents in tuning the reaction pathways will provide a viable strategy for highly selective upgrading of furan derivatives and other biomass-based oxygenates.