Insight into the micro-mechanism of Co doping to improve the deNOx performance and H2O resistance of β-MnO2 catalysts

Mn-based catalysts are desirable for selective catalytic reduction (SCR) of NO by NH3 due to their good catalytic activity and environmentally friendliness. However, the deNOx performance of single component MnO2 catalyst fails to meet the requirement and it has poor tolerance to H2O. Co doping can improve the activity and the H2O resistance of the catalysts, but the reaction mechanism remains unclear. Here, the effect of Co doping on the deNOx activity of Mn-based catalysts and the reaction mechanism of gas molecules over the beta-MnO2 (110) surface were revealed by combining experimental measurements and DFT simulations. Results show that the optimal proportion of Co can increase the deNOx efficiency of MnO2 catalysts. Doping Co enhances the adsorption and dehydrogenation of NH3 on the beta-MnO2 catalyst surface. NH2 can combine with NO to form NH2NO. Co doping promotes the breakdown of NH2NO, and the Langmuir-Hinshelwood mechanism dominates this reaction. Furthermore, Co-doped beta-MnO2 catalysts can reduce the competitive adsorption of H2O, which alleviates the poisoning effect of the catalyst.

Automated summary

The effect of Co doping on the deNOx activity of Mn-based catalysts and the reaction mechanism of gas molecules over the beta-MnO2 (110) surface were revealed by combining experimental measurements and DFT simulations. Results showed that Co doping can enhance the deNOx efficiency of MnO2 catalysts and alleviate the poisoning effect of H2O. The Langmuir-Hinshelwood mechanism dominated the reaction of NH2NO breakdown.