Design, Synthesis, and Insights into the Redox Mechanism of Highly Efficient One-Pot Cu-ZSM-5 Catalysts for the Reduction of NO x by NH3-SCR at Low Temperatures

Cu-ZSM-5 zeolites exhibit promising NH3-SCRactivityin a wide temperature window. The current challenges in preparingCu-ZSM-5 are reducing the cost and simplifying the preparation process.The one-pot method using the Cu-amine complex as the template is anexcellent strategy for solving the above problems. However, the abovemethod is still lacking in preparing Cu-ZSM-5. In this work, a one-potmethod using the Cu-(EDA)(2) complex as the template is developedto prepare the Cu-ZSM-5-O catalyst. According to the fundamental measurements,the high dispersion of copper(II) species, appropriate acidity, andCu(+) species are in favor of the NH3-SCR reaction.Among one-pot catalysts, Cu-1.8-ZSM-5-O shows excellentNH(3)-SCR performance at low temperatures (NO conversionof about 87.5% at 150 & DEG;C and N-2 selectivity above95% over the entire temperature window). The boosting activity atlow temperatures of one-pot catalysts is probably assigned to abundant[Cu(OH)](+) species and appropriate amounts of Cu+ species in Cu-ZSM-5-O. Moreover, the variable-temperature EPR andsubsequent computer simulation are used first to quantify the contentof [Cu(OH)](+) species in Cu-ZSM-5-O. The NH3-SCRmechanism at low temperatures (150 & DEG;C) on [Cu(OH)](+) species is also investigated by in situ DRIFT spectra and DFT calculations,which mainly follow the Eley-Rideal route. A complete catalyticcycle of the SCR reaction was proposed based on the [Cu(OH)](+) species by DFT calculations. Our results suggest that [Cu(OH)](+) species contribute to the adsorption and activation of NH3, thus boosting the catalytic performance.