Selective Oxidation of Alkyl Hydrocarbon with Molecular Oxygen Catalyzed by Surface-Amine-Modified Cobalt-Silicon Mixed Nano Oxides

With a one-step reverse-phase microemulsion method, surface-amine-modified cobalt-silicon mixed oxide (BA-Co-SiO₂) was successfully prepared, which was characterized by SEM, FTIR, UV-Vis DRS, XPS, TG-DTA, N₂ adsorption-desorption, and hydrophobicity/lipophilicity measurement, etc. In-situ introduction of organic amine on the surface caused three positive effects on the improvement of the catalytic oxidation ability: the first one is to generate a higher specific surface area; the second one is to modify the surface of the catalyst to be more hydrophobic and lipophilic; and the third one is to facilitate the generation of Co(III) with a higher valence state that owns a stronger oxidation ability. Under the solvent-free conditions and with molecular oxygen as the oxidant, BA-Co-SiO₂ showed a much higher catalytic activity for the selective oxidation of ethylbenzene compared with Co-SiO₂ without amine. The reported results supplied a good reference for designing the efficient catalyst through the modification of the surface property and catalyst’s structure with a simple in-situ method.