Effect of Different Zinc Species on Mn-Ce/CuX Catalyst for Low-Temperature NH3-SCR Reaction: Comparison of ZnCl2, Zn(NO3)2, ZnSO4 and ZnCO3

The effects of four distinct zinc species (ZnCl2, Zn(NO3)(2), ZnSO4, and ZnCO3) on aMn-Ce codoped CuX (MCCX)catalyst were investigated and contrasted in the low-temperature NH3-SCR process. Aqueous solutions of ZnCl2, Zn(NO3)(2), ZnSO4, and ZnCO3 were used to poison the catalysts. The catalytic activity of all catalysts was assessed, and their physicochemical properties were studied. There was a notable drop trend in catalytic activity in the low temperature range (200 C-circle) after zinc species poisoning on MCCX catalyst. Interestingly, ZnSO4 and ZnCO3 on MCCX catalyst had more serious effect on catalytic activity than Zn(NO3) (2) and ZnCl2 from 150 C-circle to 225 C-circle, in which NO conversion of theMCCX-Zn-S andMCCX-Zn-C catalysts dropped about 20-30% below 200 C-circle compared with the freshMCCX catalyst. The zeolite X structure was impacted by Zn species doping on theMCCX catalyst, and the Zn-poisoned catalysts had less acidic and lower redox ability than freshMn-Ce/CuX catalysts. Through the results of in situ DRIFTS spectroscopy experiments, all catalysts were governed by both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms, and the possible mechanism for poisoning theMn-Ce/CuX catalyst using various zinc species was revealed.