(532dj) Ionic Liquids Regulated La-Mn Composite Metal Oxides for Selective Oxidation of Cyclohexane

Ionic liquids (ILs) have been extensively applied in the synthesis of inorganic nanomaterials due to their unique physicochemical properties, including rich hydrogen bond network, good thermal stability and flexibility in synthesis. The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA oil) is an important industrial process and KA oil is acknowledged as a crucial intermediate for producing nylon 6 and nylon 66. However, how to construct the active center to realize the effective activation of cyclohexane C-H bond and the selective distribution of products was the bottleneck for its widely application. Therefore, it’s significant to design catalysts with high activity and selectivity for selective oxidation of cyclohexane.

In the present work, we proposed a ILs-assisted hydrothermal method for the synthesis of lanthanum manganese composite metal oxides (LMCO) for cyclohexane selective oxidation to KA oil (Scheme 1). The crystal phase structure, morphology and growth process of LMCO catalysts were effectively regulated regarding the structure orientation and template effect of ILs as shown by various characterizations. The results indicated that the structures of cation and anion have significant influence on the surface reactive oxygen species concentration, redox capacity and strong base site of LMCO catalysts. Especially for the LMCO catalyst assisted with [Bmim][HSO₄], cyclohexane conversion can be achieved up to 8.9% with 90% selectivity of KA oil. These results suggested it is an efficient way to construct catalytic active centers of LMCO catalyst to enhance their catalytic properties and this strategy could expand the application of ILs in regulating other metal oxide catalysts.