Interfacial Reaction-Directed Green Synthesis of CeO₂-MnO₂ Catalysts for Imine Production through Oxidative Coupling...

Direct oxidative coupling of alcohols with amines over cheap but efficient catalysts is a promising choice for imine formation. In this study, porous CeO₂-MnO₂ binary oxides were prepared via an interfacial reaction between Ce₂(SO₄)₃ and KMnO₄ at room temperature without any additives. The as-prepared porous CeO₂-MnO₂ catalyst has a higher fraction of Ce³⁺, Mn³⁺, and Mn⁴⁺ and contains larger surface area and more oxygen vacancies. During the oxidative coupling reaction of alcohol with amine to imine, the as-obtained CeO₂-MnO₂ 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 CeO₂ and MnO₂ in the CeO₂-MnO₂ catalyst, exhibiting especially a positive synergistic effect in the direct coupling of alcohol and amine reaction.