Efficient Water Resistance via High-Spin-State Manganese Species in Low-Temperature NH3-SCR

Development of highly efficient catalysts for low-temperature NH3-SCR remains a significant challenge, especially in the presence of high concentrations of water vapor. Herein, we have engineered a unique MnCeO2-TDA catalyst with high-spin manganese species by using electron-donating thiophene groups, achieving an excellent NO conversion of over 93% at 160 °C and under 60,000 mL·g-1·h-1 conditions in the higher water vapor of 10-20 vol %. Experimental and theoretical calculations demonstrate that, due to, asymmetrically occupied eg orbitals, high-spin Mn3+ triggers a strong Jahn-Teller distortion, which greatly decreases the O2 dissociation energy (from 2.837 to 1.979 eV) and coactivates O2 and H2O to form the *OOH oxidative species. This enhanced redox ability facilitates NO oxidation and the "fast SCR" reaction, leading to excellent deNOx efficiency under higher levels of water vapor at low temperatures. This work offers a new approach to modulating the spin state of active centers to enhance water resistance in flue gas purification.