Performance of ventilation air methane combustion over transition metal oxide oxygen carriers

Abstract

The performance of combustion of ventilation air methane (VAM) over transition metal oxide oxygen carriers was studied through experiments with using tube reactors. The results show that the activity of activated oxygen carriers in converting CH4 to CO2 is as follows:CuO60/γ-Al2O3 > NiO60/γ-Al2O3 > Fe2O360/γ-Al2O3. CH4 conversion based on CuO60/γ-Al2O3 decreases with increasing gas hourly space velocity, but increases with increasing bed temperature and CuO loading. The lower the initial CH4 concentration of ventilation air methane, the lower is the temperature for the CH4 conversion of 90%. There are catalytic combustion mechanisms and chemical-looping combustion mechanisms for CH4 combustion over both CuO60/γ-Al2O3, for which dispersion of the active component is low but loading is high, and CuO5.5/γ-Al2O3, for which dispersion of the active component is high but loading is low. There exists a maximum for CH 4 conversion based on the catalytic combustion mechanism at some temperatures, and when the bed temperature is higher than this temperature, the contribution of chemical-looping combustion is greater than that of catalytic combustion. The initial activity of CuO5.5/γ-Al2O3 is higher than that of CuO60/γ-Al2O3, while the stability of CuO60/γ-Al2O3 activity is better than that of CuO5.5/γ-Al2O3 activity under the same conditions.

Keywords

• ventilation air methane
• methane conversion
• oxygen carrier
• chemical-looping combustion
• catalytic combustion