Influence of the Surface Species over Co3O4 on the Formaldehyde Catalytic Oxidation Performance

The Co3O4 catalysts were prepared via precipitation methods, and then were pretreated in N-2 or O-2 at different temperatures. Based on the study of formaldehyde catalytic oxidation, the catalytic performances were investigated with the detailed surface characterization via temperature programmed desorption (O-2/CO2- TPD, HCHO-TPSR), thermogravimetric-differential scanning calorimetry(TG-DSC) and in situ diffuse reflectance infrared fourier transform spectroscopy (in situ DRIFTS). The results presented that Co3O4-N-2-200 showed the optimal catalytic performance, because there were rich unsaturated coordination centers of Co3+ and negative oxygen ions with weak bond strength on the surface of Co3O4-N-2-200, which was ready to adsorb formaldehyde to form bidentate formate, and then decompose to products via monodentate formate. With increasing pretreatment temperature, the amount of negative oxygen ions decreased, accordingly the catalytic activity for formaldehyde catalytic oxidation decreased due to slow decomposition rate of desorbed bidentate formate.