Construction of defects-rich TiO2-supported Pd catalyst for phenol hydrogenation with ball-milling process

An active catalyst Pd/TiO2(M) for phenol hydrogenation to cyclohexanone was constructed via a ball-milling process. This mechanical process avoids the thermal reduction in hydrogen atmosphere and creates oxygen vacancies on TiO2, which prevents the oxide support encapsulating active metal palladium due to the strong metal-support interaction(SMSI) but improves the catalytic performance of palladium. Under atmospheric hydrogen generated by electrolyzingwater, phenol can be hydrogenated to cyclohexanone selectively. Characterizations, control experiments and DFT calculations reveal that surface defective structures of Ti3+-Ov can stabilize Pd nanoclusters and promote the formation of electron-rich Pd. This kind of electronic metal-support interaction facilitates the dissociative adsorption of phenol, so that Pd/TiO2(M) exhibits outstanding catalytic activity and selectivity for phenol hydrogenation to cyclohexanone.