The scope and reaction mechanism of CeO₂ catalysis in the imine formation from alcohols and amines were investigated. CeO₂ catalyst was applicable to the synthesis of imines from various alcohols and amines, and also to the synthesis of imines by homo-coupling of aromatic methylamines, although aliphatic alcohols and sterically hindered alcohols such as secondary alcohols were not suitable substrates for the CeO₂ catalyst system. Based on the kinetic and spectroscopic studies, the reaction mechanism of the imine formation from benzyl alcohol and aniline over CeO₂ was proposed. The reaction proceeds by the five steps: (i) dissociative adsorption of alcohol on CeO₂ to form the alkoxide adspecies and proton, (ii) oxidative dehydrogenation of the alkoxide adspecies to aldehyde adspecies by the lattice oxygen on CeO₂ along with reduction of Ce⁴⁺ to Ce³⁺, (iii) nucleophilic addition of amine to the aldehyde adspeices to produce carbinolamine adspecies, and (iv) dehydration of carbinolamine adspecies to the corresponding imine and H₂O. (v) Finally, oxidation of Ce³⁺ to Ce⁴⁺ by O₂ from air to regenerate CeO₂ catalyst. The rate-determining step is the step (ii), particularly the dissociation of benzylic C-H bond at the α-carbon of OH group in benzyl alcohol by the lattice oxygen of CeO₂, and the oxidation follows Mars-van Krevelen mechanism. The reactive lattice oxygen species are mobile ones at the redox sites of CeO₂, and the high mobility of the oxygen species is responsible for the high activity in the reaction. Based on the reaction mechanism, the low reactivity of the aliphatic alcohols and secondary alcohols can be explained by the steric hindrance, stability of the carbonyl adspecies and/or C-H bond dissociation energy.

研究了CeO ₂催化醇和胺形成亚胺的反应范围和反应机理。CeO ₂催化剂适用于由各种醇和胺合成亚胺，也适用于通过芳族甲胺的均相偶联合成亚胺，尽管脂族醇和位阻醇（例如仲醇）不适用于CeO ₂催化剂体系。基于动力学和光谱学研究，提出了由苄醇和苯胺在CeO _2上形成亚胺的反应机理。反应通过五个步骤进行：（i）醇在CeO ₂上的解离吸附形成醇盐形态和质子；（ii）CeO ₂上的晶格氧将醇盐形态氧化脱氢为醛形态，以及将Ce ⁴⁺还原为Ce ³⁺；（iii）胺向醛形态的亲核加成以产生甲醇胺adspecies，和（iv）甲醇胺adspecies的脱水成相应的亚胺和H ₂ O.（v）的最后，铈氧化³⁺至Ce的⁴⁺被O ₂从空气中以再生的CeO ₂催化剂。决定速率的步骤是步骤（ii），特别是通过CeO的晶格氧使苄醇中的OH基的α-碳上的苄基CH键解离_{如图2所示}，氧化遵循Mars-van Krevelen机理。反应性晶格中的氧是可移动的，在CeO ₂的氧化还原位，并且氧的高迁移率是反应中高活性的原因。基于反应机理，脂族醇和仲醇的低反应性可以通过位阻，羰基种类的稳定性和/或CH键离解能来解释。