The CoxOy/AC catalysts were prepared by wet impregnation method for toluene oxidation removal from air. The thermal stability of cobalt nitrate and Co oxide on the activated carbon (AC) support surface was analysed by thermal analysis. The physicochemical properties of the prepared catalysts were characterised by XRD, SEM, H2-TPR, and XPS. AC support with high specific surface area and developed pore structure can promote the dispersion of Co species on its surface to form highly dispersed Co oxide species. The participation of AC supports can promote the partial reduction of Co3O4 species to CoO species to coexist in the prepared CoxOy/AC catalyst. The Co2+/Co3+ ratio was significantly affected by the calcination temperature, and the appropriate Co2+/Co3+ ion pairs in the studied CoxOy/AC catalyst is helpful to the activity of O2 molecules to form reactive oxygen species. The oxygen species composition on the catalyst surface is obviously affected by the calcination temperature, which plays an important role in toluene oxidation reaction. The studied CoxOy/AC catalysts exhibited excellent toluene oxidation removal performances. The conversion of toluene exceeded 97% and 99% at 240°C and 250°C, respectively, and maintained good stability within 700 min. That is to say, the concentration of toluene in the air can be reduced from 10,000 ppm to less than 40 ppm by using the CoxOy/AC catalyst.
Keywords: Co oxide; atmosphere; catalyst; catalytic oxidation; toluene.