摘要
Cu-SSZ-13催化剂已被证实是高效NH_(3)-SCR催化剂。然而,其经过严重水热老化(950℃)后仍会导致不可逆失活。本文通过考察引入的第二活性金属(Ce)离子浓度对Cu-SSZ-13催化剂的活性位性质及其催化活性的影响,揭示了活性位与催化活性之间的关系。结果表明,Cu-SSZ-13中引入的Ce离子并不会成为NH_(3)-SCR反应的活性中心,而仅起到调节Cu活性位和表面酸性位的位置和数量的作用。通过XPS、H_(2)-TPR、NH_(3)-TPD和活性分析结果可知,低铈负载(约0.2%)下,少量的Ce可进入离子交换位点,有助于稳定SSZ-13骨架结构和抑制CuO_(x)团簇生成的作用(950℃老化后劣化率仅为6%),还能实现高铜负载(Cu负载量为3.01%)与丰富的L酸、B酸位,从而使其具有高的NO转化率、更宽的NO反应温度窗口和优异的水热稳定性。而引入过量的铈离子对Cu-SSZ-13的催化活性和水热稳定性产生不利影响,导致SCR性能下降。
The Cu-SSZ-13 catalyst has been proved to be a high-efficiency NH_(3)-SCR catalyst. However, it will still cause irreversible inactivation after severe hydrothermal aging(950 ℃). This paper reveals the relationship between the active sites and the catalytic activity of the Cu-SSZ-13 catalyst by investigating the effect of the concentration of the second metal ion(Ce) introduction on the properties of the active sites(copper sites, acid sites) and the catalytic activity. The results show that the Ce ion introduction in Cu-SSZ-13 does not become the active center of the NH_(3)-SCR reaction, but only plays a role in regulating the position and quantity of Cu sites in the CHA cage and the amount of acid sites on the surface of the catalyst. According to XPS, H_(2)-TPR, NH_(3)-TPD and activity analysis results, a small amount of Ce under low cerium loading(about 0.2%) can enter the ion exchange site, which is conducive to stabilizing the skeleton structure of SSZ-13 and inhibiting the formation of CuO_(x) clusters(the degradation rate after aging at 950 ℃ is only 6%), it can also achieve high copper loading(3.01% Cu loading) and rich L acid and B acid sites, resulting in high NO conversion, wider reaction temperature window and excellent hydrothermal stability. Nevertheless, the introduction of excessive cerium ions has a negative effect on the catalytic activity and the hydrothermal stability of the Cu-SSZ-13 catalyst, leading to a decrease in SCR performance.
作者
赵文怡
申孟林
朱悦然
任旭东
李新刚
ZHAO Wen-yi;SHEN Meng-lin;ZHU Yue-ran;REN Xu-dong;LI Xin-gang(School of Chemical Engineering&Technology,Tianjin University,Tianjin 300350,China;State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization,Baotou Research Institute of Rare Earths,Baotou 014030,China)
出处
《稀土》
CAS
CSCD
北大核心
2024年第2期41-56,共16页
Chinese Rare Earths
