CeO2-promoted BaO-MnOx catalyst for lean methane catalytic combustion at low temperatures: Improved catalytic efficiency and light-off temperature

Abstract

In this research, the effect of various promoters (Zr, La, Ce, and Y) on the physicochemical features and catalytic activities of the BaO(10)-MnOx prepared by the mechanochemical preparation route was investigated in the catalytic combustion of lean methane. Incomplete methane combustion as a result of the burning of natural gas in industries is the major reason to use a catalytic system to reduce the pollutants formation (NOx, COx, etc.) and improve the combustion efficiency and proceeds towards complete combustion. In our previous study, we performed the methane combustion reaction on the mechanochemical synthesized BaO(x)-MnOx catalysts with various contents of BaO (5–20 wt%), and the results indicated that the addition of 10 wt% of BaO to MnOx could remarkably improve the catalytic efficiency due to the enhance the oxygen mobility and reduction features. In the present study, the structural properties of the synthesized catalysts were specified by XRD, BET, H2-TPR, O2-TPD, and SEM techniques. It is observed from the O2-TPD technique that the addition of promoters into the BaO-MnOx catalyst resulted in the increase in oxygen mobility, which could rise the catalytic activity. The addition of CeO2 has a more positive effect on the catalytic activity due to the higher surface area and oxygen storage capacity. The obtained results revealed that the CeO2(3)-BaO(10)-MnOx catalyst possessed the superior performance in the methane combustion. The 90% of CH4 conversion was obtained at about 350 °C over this catalyst. The effect of calcination temperature, feed ratio, GHSV, hysteresis curve, pretreatment atmospheres, and the presence of CO2 and moisture was evaluated on the catalytic efficiency. After 50 h of continuous reaction at 450 °C, the selected catalyst showed high stability and the catalyst morphology was not significantly altered. Furthermore, CO oxidation was performed over the CeO2(3)-BaO(10)-MnOx catalyst, and the results indicated that the CO conversion was reached 100% at 250 °C.