Effect of Ceria on redox-catalytic property in mild condition: A solvent-free route for imine synthesis at low temperature

• Published in: Applied catalysis. B, Environmental Vol. 227; pp. 209 - 217
• Main Authors: Zhang, Hepeng, Wu, Chen, Wang, Wenbin, Bu, Jun, Zhou, Fengtao, Zhang, Baoliang, Zhang, Qiuyu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.07.2018; Elsevier BV
• Subjects: Air temperature; Alcohol; Alcohols; Benzaldehyde; Catalysis; Catalysts; Catalytic activity; Ceria; Cerium oxides; Chemical synthesis; Energy consumption; Imine synthesis; Imines; Impact analysis; Industrial applications; Low temperature; Mild conditions; Oxygen; Redox catalysis; Scaling; Solvent-free; Solvents; Studies; Temperature effects; Imine synthesis; Mild conditions; Redox catalysis; Solvent-free; Ceria
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.01.012

Imines synthesis from alcohols and amines catalyzed by high-efficiency ceria in solvent-free, low temperature conditions. [Display omitted] •Low-energy consuming, environmental-friendly and easy scaling-up preparation of CeO2.•Excellent catalytic performance (99% yield in 333 K for 24 h) towards imines synthesis from benzyl alcohol and amine.•High catalytic activity on 10-fold magnification solvent-free experiments for synthesis of benzalaniline and derivatives.•Benzyl alcohol oxidized to benzaldehyde is the rate determining step of the reaction.•Higher acidic sites, specific surface area and surface oxygen content lead to strong catalytic ability of ceria. Five different nanocerias were prepared and used to catalyze the direct coupling of alcohol and amine to the corresponding imines under air atmosphere at low temperature. The catalytic efficiencies have great differences, CeO2 prepared by coprecipitation at room temperature (called CeO2-5) has the best catalytic activity, whose yield reaches 99% at 303 K for 36 h, 100 times higher than the nano-octahedras ceria (called CeO2-4) and also higher than the catalytic performance of most reported catalysts. Such phenomena are ascribed to the higher acidic sites, specific surface area, and proportions of surface oxygen. The results of DRIFTS demonstrated that the alcohol oxidized to benzaldehyde was the rate determining step in this reaction. Furthermore, CeO2-5 still shows excellent catalytic performance on 10-fold magnification experiments without any addition of solvent. Besides, it has the advantages of simple process, low energy consumption and practical scaling-up as well as good universality towards this kind of reaction, showing every prospect in industrial application.