Mutual inhibition mechanism of simultaneous catalytic removal of NO and toluene on Mn-based catalysts.

NO and toluene have been identified as the dominant air pollutants in solid wasted combustion, and it is of great importance to remove these two pollutants simultaneously. Here, we found that Mn/CeO and Mn/TiO exhibited a bifunctional property in both NO reduction and toluene oxidation, and both of which could achieve 80% of conversion rate in NO reduction and toluene oxidation processes. However, the activity of both Mn/CeO and Mn/TiO decreased in simultaneous removal of NO and toluene compared with separate NO reduction and toluene oxidation. This indicates that there is a mutual inhibition between NO reduction and toluene oxidation in simultaneous removal process over Mn-based catalysts, attributing to the competitive adsorption and utilization of active oxygen. In detail, the adsorption of toluene occupied the Lewis acid sites and restrained the NH adsorption. Meanwhile, the competitive utilization of active oxygen by NH/NO inhibited toluene oxidation to CO by active oxygen species as the reaction between NH/NO and active oxygen species would occur more easily.