Unveiling the role of microwave induction on V2O5@AC catalyst with enhanced activity for low temperature NH3-SCR reaction: Experimental and DFT study

Supported V2O5/AC catalysts synthesized under microwave assistance were applied for selective catalytic reduction of NO by NH3 (NH3-SCR). The activity evaluation demonstrated that introducing microwave during the impregnation could significantly improve deNOx performance of V2O5@AC catalyst, of which V2O5@AC-300 achieves the highest deNOx activity at low temperature. Several comprehensive characterizations including SEM, H2-TPR, Raman, EPR, and XPS manifested that microwave induce the high dispersion of V2O5 species and more exposed active sites. Additionally, V2O5@AC-300 exhibits excellent redox properties and abundant surface chemisorbed oxygen species, which may be due to the strong coupling interaction between microwave and activated carbon and vanadium species, thereby creating more coordination-unsaturated V and defects. DFT calculations further verified that oxygen vacancy doping could greatly promote the adsorption and activation of reactants, which is beneficial to SCR activity. Moreover, V2O5@AC-300 possesses a larger adsorption capacity of NH3 than that of V2O5@AC, indicating that microwave irradiation could effectively modulate the adsorption sites of reactants on catalysts, especially for Lewis acid sites. In situ DRIFT results revealed more amount of adsorbed NO2 and monodentate nitrate species due to abundant oxygen vacancies, were formed in V2O5@AC-300, fulfilling the acceleration of the SCR process.

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