Enhanced activity of Au/NiO nanohybrids for the reductive amination of benzyl alcohol

Gold nanoparticles were prepared by sol immobilization (AuSI) or deposition precipitation (AuDP), then deposited on NiO and commercial TiO2(P25). The Au/NiO catalysts showed higher activity and yield to the secondary amine, compared to Au/TiO2catalysts, when tested for the reductive amination of benzyl alcohol with isopropylamine. We attribute this result to a synergistic effect between Au and NiO. Moreover, as a result of the protective effect of the polyvinyl alcohol used in the sol immobilization synthesis, the gold nanoparticles on NiO demonstrate an increased resistance to structural changes during the reaction. This effect results in enhanced catalytic efficiency in terms of activity, and better stability against deactivation.