Interfacial Reaction-Directed Green Synthesis of CeO<sub>2</sub>–MnO<sub>2</sub> Catalysts for Imine Production through Oxidative Coupling of Alcohols and Amines
Jingwen Li, Riming Hu, Wei Liu, Daowei Gao, Huaiqing Zhao, Chunsheng Li, Xuchuan Jiang, Guozhu Chen
Abstract
Direct oxidative coupling of alcohols with amines over cheap but efficient catalysts is a promising choice for imine formation. In this study, porous CeO 2 -MnO 2 binary oxides were prepared via an interfacial reaction between Ce 2 (SO 4 ) 3 and KMnO 4 at room temperature without any additives. The as-prepared porous CeO 2 –MnO 2 catalyst has a higher fraction of Ce 3+, Mn 3+, and Mn 4+ and contains larger surface area and more oxygen vacancies. During the oxidative coupling reaction of alcohol with amine to imine, the as-obtained CeO 2 –MnO 2 catalyst is motivated by the above encouraging characteristics and exhibits superior catalytic activity (98% conversion and 97% selectivity) and can also work effectively under a wide scope of temperatures and substrates. The in-depth in situ DRIFTS and density functional theory (DFT) results demonstrate that there is a strong interaction between CeO 2 and MnO 2 in the CeO 2 –MnO 2 catalyst, exhibiting especially a positive synergistic effect in the direct coupling of alcohol and amine reaction.