Regulation of Coordination Environment Over Cu Sites: Triggering the Efficient Selective Catalytic Reduction of NO_x Using NH₃ as Reductant

ABSTRACT

The design of the controlled coordination environment over Cu sites for selective catalytic reduction of NO_x using NH₃ as reductant (NH₃‐SCR) is still challenging. A series of dispersed Cu catalysts with different coordination environments were prepared by metal‐template/metal‐ion exchanged method and random grafting method. Meanwhile, their NH₃‐SCR catalytic performance was explored. The catalyst C/T9‐M, prepared through metal‐template/metal‐ion exchanged method, achieved relatively good activity with the NO_x conversion of ~100% in the temperature region of 250°C°C–400°C. It was ascribed to C/T9‐M containing a higher amount of the isolated Cu²⁺ and without occurring the direct oxidation of NH₃ to NO at high temperature. On the contrary, C/T9‐R synthesized using random grafting method demonstrated more outstanding NH₃‐SCR performance with the NO_x conversion of ~100% in the temperature region of 200°C°C–350°C due to more [Cu(OH)]⁺. Our experimental results confirmed that the active [Cu(OH)]⁺ was capable of facilitating the low‐temperature activity for NH₃‐SCR and the isolated Cu²⁺ facilitates NO_x conversion under high temperature. In addition, compared with the C/T9‐R catalyst, the C/T9‐M catalyst had less Cu loading, which laterally proved that controlling the coordination environment of Cu sites could effectively improve the NH₃‐SCR performance under high temperature. What's more, C/T9‐M had more glorious the resistance of H₂O and SO₂ than C/T9‐R. This work furnishes reformatory pathway for the invention of noticeable NH₃‐SCR catalysts. It is expedient for academic and practical applications in the future.