# Effect of Zr Modification on NH\({}_{3}\)-SCR Reaction Performance of Cu-Ce/SAPO-34 Catalysts
###### Abstract  
Molecular sieve catalysts containing transition metals have been attracting attention for their potential applications in various fields, including environmental and industrial catalysis. A Cu-Ce-Zr/SAPO-34 series of molecular sieve catalysts were prepared by the impregnation method, and the effect of Zr introduction on the selective catalytic reduction of NO by Cu-Ce/SAPO-34 molecular sieve catalysts was explored. Through various characterization methods, the physical and chemical properties of the catalysts were analyzed, and the denitration mechanism of the molecular sieve catalyst was discussed. This study found that the total acid content of the acid sites on the catalyst surface decreased with the introduction of Zr, leading to a decrease in the denitration efficiency of the catalyst. At 350-400 \({}^{\circ}\)C, the denitration efficiency of the 4 Cu-4 Ce-4 Zr/SAPO-34 catalyst was over 80%, and at 400-500 \({}^{\circ}\)C, it was over 99%. Moreover, excessive metal Zr could destroy its CHA structure and decrease the denitration efficiency of the catalyst. This study analyzed the reaction mechanism of NH\({}_{3}\)-SCR of Zr-modified polymetallic zeolites and the effect of Zr modification on the NH\(3\)-SCR reaction results. This study contributes to the understanding of the performance of molecular sieve catalysts containing transition metals. Reliable conclusions were obtained, which offer data support for future research in the field of NH\({}_{3}\)-SCR. Cu-Ce-Zr/SAPO-34; molecular sieve catalyst; selective catalytic reduction; modification +
Footnote †: journal: Medical  
efficiency of catalysts followed the following order: Cu-Mn > Cu > Mn; when the reaction conditions were higher than 200 \({}^{\circ}\)C, the order was: Cu > Cu-Mn > Mn, indicating that Cu catalysts are superior to Mn catalysts, and bimetallic oxide catalysts are superior to single-metal-oxide catalysts at a temperature lower than 200 \({}^{\circ}\)C. In conclusion, it was proposed to select Cu as the active component of the catalyst. In terms of the carrier, most mainstream researchers choose zeolite molecular sieves, active carbon, TiO\({}_{2}\), etc., as the carrier of catalysts. Zeolite molecular sieves are widely used in various fields because of their porosity, selective adsorption of molecules through channels, large specific surface area, and the fact that they are excellent catalyst carriers. As reported in the literature in [7], the denitrification performance of Cu Mn/SAPO-34 is generally better than that of Cu Mn/ZSM-5; [PERSON] pointed out that [8] Cu/SAPO-34 catalysts have a wide active temperature window, excellent hydrothermal stability, and resistance to alkali metal and alkaline earth metal poisoning. According to the actual conditions of the laboratory, an SAPO-34 molecular sieve was proposed to be used as the catalyst carrier. To obtain a superior denitration performance and a wider range of applications, SCR denitration catalysts are mostly bimetallic or even polymetallic in order to obtain the physical and chemical properties of various metals. Many scholars [9; 10] have found that doping with metal Ce has a positive effect on the denitration ability of Cu-based molecular sieve catalysts. Ce can improve the thermal stability of the catalyst, improve the distribution of active substances on the catalyst surface, and enhance the redox performance of the catalyst. Therefore, Ce was proposed to be used as a metal in a multi-metal-oxide catalyst. According to [PERSON]'s research [11], Zr can increase the oxygen vacancy concentration of Cu-Ce metal oxide catalysts, enhance their oxidation-reduction capacity, and improve the catalysts' adsorption capacity for NO\({}_{x}\). However, it will slightly reduce their denitration performance. Some scholars [12] found that doping with Zr can inhibit the aggregation of Cu on the catalyst surface, promote the dispersion of Cu, increase the concentration of Cu species on the catalyst surface, and improve the resistance to Ca poisoning.