Catalytic combustion of PVOCs on MnOx catalysts

Abstract

In this study, manganese oxide (MnOx) catalysts were prepared by using hard-template (MnOx-HT) and precipitation (MnOx-PC) methods. The prepared MnOx catalysts were systematically characterized by XRD, TEM, BET, XPS, O2-TPD, and H2-TPR analyses. The activity of the catalysts was investigated in the catalytic combustion of PVOCs, such as benzene, toluene, xylene, and ethylbenzene, in air. Results indicate that the chemical composition and structure of the prepared MnOx oxide catalysts are obviously affected by the preparation methods. The T90 corresponding to the catalytic combustion of xylene, ethylbenzene, toluene, and the T60 of benzene over the MnOx-HT catalyst are 200°C, 205°C, 210°C, and 225°C, which are much lower than that over MnOx-PC. The catalytic combustion of the PVOCs over the MnOx-HT catalyst follows the order xylene>ethylbenzene>toluene>benzene. Both the MnOx-HT and MnOx-PC catalysts exhibit stable catalytic performance during the combustion of toluene. Therefore, the superior catalytic performance of the MnOx-HT catalyst can be attributed to the high MnO2 content, high concentration of surface reactive oxygen, highly ordered mesopores, large specific surface area, good oxygen mobility, and low-temperature reducibility. In addition, the catalytic combustion of the phenyl compounds is affected by their inherent characteristics such as structural stability, molecular polarity, and dimensions.