Poisoning Mechanism Study of Metal Ions on a Three-Dimensional Ordered Macroporous Structure Ce_0.2Mn_0.2/3DOM-TiO₂ Catalyst for Low-Temperature SCR of NO with NH₃

Abstract

Metallic ions such as Cd, Pb, and Zn are commonly present in nonelectric industry flue gas, resulting in catalyst poisoning and deactivation, thereby hampering the use of SCR technology for flue gas treatment in nonelectric industries. In this paper, the catalyst with a three-dimensional ordered macrophage (3DOM) structure support was prepared to enhance its antipoisoning performance. Additionally, the possible mechanism of catalyst metal ion poisoning was investigated. The XPS results revealed a significant decrease in the catalyst's chemisorbed oxygen content after Cd and Pb poisoning. The NH 3 -TPD analysis indicated a decrease in the acid sites present on the catalyst's surface and a weakening of its redox capacity after Cd poisoning, which led to a degradation of the SCR performance over the CMT--3DOM catalyst. In situ DRIFTS experiments manifested that SCR progression on the CMT-3DOM catalyst followed both L-H and E-R mechanisms. Cd-poisoned catalysts primarily followed the L-H mechanism, while on Pb-and Zn-poisoned catalysts, the E-R mechanism dominated.