MnO dispersion regulated P-Mn interactions in P-doped MnO /TiO2 catalyst for efficient NH3-SCR denitration
Junqi Wang, Rongkun Jiang, Ruoxuan Bai, Fei Gao, Zixiao Yu, Jiangxiao Qiao, Yiqing Zeng, Shule Zhang, Zhaoxiang Zhong
Abstract
Modification with strong acidic species serves as an effective strategy to broaden the active temperature window of MnO x based catalysts for ammonia selective catalytic reduction (NH 3 -SCR) of NO x . However, strong acidic species always decrease the redox properties of MnO x , which hinders the quest for better performance of MnO x based NH 3 -SCR catalysts. Herein, the dispersion of MnO x on P modified MnO x /TiO 2 (labeled as Mn(X)/TiP (X = O, A, N, represents the Mn precursors of manganese dioxide, manganese acetate and manganese nitrate, respectively)) catalysts were regulated via changing manganese precursors to investigate its effects on P-Mn interactions and catalytic performance. It is found that the low-temperature NH 3 -SCR performance follows the order Mn(A)/TiP > Mn(O)/TiP > Mn(N)/TiP, which is consistent with the degree of MnO x dispersion. The increase of MnO x dispersion can contribute to the formation of a large amount of isolated MnO x nanoparticles, which reduces the passivation of P on other active Mn sites due to the formation of P-Mn interactions and promotes the establishment of an efficient redox cycle between Mn and Ti (Ti 4+ + Mn 2+/3+ ↔ Ti 3+ + Mn 3+/4+ ), thereby promoting the NH 3 -SCR denitration reaction via enhancing the activation of NH 3 and NO x . This work sheds an insight into the effect of MnO x dispersion on regulating the NH 3 -SCR performance of P-modified MnO x /TiO 2 catalysts and provides an efficient strategy to solve the imbalance between acidity and redox property during the design and developments of efficient NH 3 -SCR catalysts.