Poisoning mechanism of potassium and calcium on a Mn-based quasi-MOF de-NO_x catalyst

Despite extensive research on alkali resistance of denitrification (de-NO_x) catalysts, the synergistic poisoning mechanism of alkali and alkaline-earth metals on de-NO_x catalysts, particularly Mn-based catalysts, remains unresolved. This study investigates the co-poisoning effects of K and Ca on the de-NO_x activity of Mn-based quasi-MOF (Metal Organic Framework) catalysts, specifically TEOS&Mn-BTC (a catalyst previously designed by our team, TEOS and BTC represent tetraethyl orthosilicate and trimesic acid, respectively). We found that the coexistence of K and Ca elevates the d-band center, which improves the electron mobility ability of the catalyst, thus enhancing the electron transfer between Mn and O in the Si-O-Mn electron-metal-carrier coordination structure, which further promotes the occurrence of acid and redox circulations while strengthening the electron-metal-carrier interaction. Moreover, the increase in the d-band center enhances the charge transfer between the catalyst and the adsorbate, thereby further enhancing the adsorption of NH₃ and NO. These findings elucidate the anti-poisoning mechanism of TEOS&Mn-BTC and provide theoretical insights for designing alkali/alkaline-earth-resistant de-NO_x catalysts.