Au–Pd alloy nanoparticle catalyzed selective oxidation of benzyl alcohol and tandem synthesis of imines at ambient conditions

• Published in: Catalysis today 2014-10, Vol.235, p.152-159
• Main Authors: Cui, Wenjing, Xiao, Qi, Sarina, Sarina, Ao, Wulan, Xie, Mengxia, Zhu, Huaiyong, Bao, Zhaorigetu
• Format: Article
• Language: English
• Subjects: Amine; Benzyl alcohol; Catalysis; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Gold and palladium alloy nanoparticles; Imine; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Tandem synthesis; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2014.04.015

•The alloy nanoparticles on ZrO2 are active catalyst for oxidation of benzyl alcohols.•They can catalyze the synthesis of imines from benzyl alcohols and amines.•The catalyst exhibits excellent performance at ambient temperature and pressure.•The optimal catalyst is 3.0wt% Au–Pd@ZrO2 with a Au:Pd molar ratio 1:1.•The alloy surface has higher charge heterogeneity than that of pure component metals. Alloy nanoparticles (NPs) of gold and palladium on ZrO2 support (Au–Pd@ZrO2) were found to be highly active in oxidation of benzyl alcohols and can be used for the tandem synthesis of imines from benzyl alcohols and amines via a one-pot, two-step process at mild reaction conditions. The first step of the process is oxidation of benzyl alcohol to benzaldehyde, excellent yields were achieved after 7h reaction at 40°C without addition of any base. In the second step, aniline was introduced into the reaction system to produced N-benzylideneaniline. The benzaldehyde obtained in the first step was completely consumed within 1h. A range of benzyl alcohols and amines were investigated for the general applicability of the Au–Pd alloy catalysts. It is found that the performance of the catalysts depends on the Au–Pd metal contents and composition. The optimal catalyst is 3.0wt% Au–Pd@ZrO2 with a Au:Pd molar ratio 1:1. The alloy NP catalyst exhibited superior catalytic properties to pure AuNP or PdNP because the surface of alloy NPs has higher charge heterogeneity than that of pure metal NPs according to simulation of density function theory (DFT).