Experimental and First‐Principles Evidence for Interfacial Activity of Ru/TiO2 for the Direct Conversion of m‐Cresol to Toluene

The selective cleavage of C−O bonds in phenolic species is perhaps the most difficult transformation required for converting biomass‐derived monomers to aromatic fuels and chemicals. Metals supported on reducible oxides, such as Ru/TiO2, have demonstrated considerable promise for a variety of selective C−O cleavage reactions, but the active site has been subject of a great deal of speculation. This paper employs a combination of theory and experiments to investigate the nature of the active site for the selective transformation of m‐cresol to toluene. Through variation of metal loading, particle size and support phase, we show that sites responsible for direct C−O cleavage of m‐cresol lie at the perimeter of the metal particle. The activation barrier for C−O cleavage is reduced from 1.4 eV on the Ru surface to 0.7 eV at an interfacial site. The introduction of water facilitates a further reduction to 0.3 eV via a proton‐assisted C‐O cleavage. These results answer a longstanding question regarding the nature of these important active sites, with broad implications for biomass upgrading. Break it! A combination of theory and experiments were used to investigate the nature of the active site for the selective transformation of m‐cresol to toluene. Through variation of metal loading, particle size and support phase, it was demonstrated that sites responsible for direct C−O cleavage lie at the perimeter of the metal particle.