Activity enhancement of Ru/CeO2 for N-alkylation of amines with alcohols through tailoring metal-support interaction

Efficient and selective N-alkylation of amines with alcohols via transfer hydrogenation is of great significance but extremely challenging. Here, we report the production of N–benzylaniline (BZA) from benzyl alcohol and aniline over various fine-shaped Ru/CeO2 catalysts. The Ru/CeO2–R (rod) catalyst exhibits the highest catalytic activity among all catalysts, in which the yield of BZA reaches up to 88% with complete conversion, significantly higher than that of Ru/CeO2-C (cube, 52%) and Ru/CeO2-O (octahedron, 32%). Extensive experimental investigations disclose that Ru nanoparticles with a metallic state promote the dehydrogenation of the hydroxyl group and hydrogenation of imines, while the CeO2–R with rich oxygen vacancies facilitates the adsorption and activation of reactants. Furthermore, kinetic studies and time-resolved operando dual-beam Fourier transform infrared spectroscopy analysis confirms the transfer hydrogenation pathway, in which the benzyl alcohol is firstly dehydrogenated to benzaldehyde, followed by spontaneously reacting with aniline, and finally transforms into the N-benzylaniline rapidly.