New insight into Cu/SAPO-34 preparation procedure: Impact of NH4-SAPO-34 on the structure and Cu distribution in Cu-SAPO-34 NH3-SCR catalysts
New insight into Cu/SAPO-34 preparation procedure: Impact of NH4-SAPO-34 on the structure and Cu distribution in Cu-SAPO-34 NH3-SCR catalysts
复制标题
Cu/SAPO-34 制备过程的新见解：NH4-SAPO-34 对 Cu-SAPO-34 NH3-SCR 催化剂结构和 Cu 分布的影响
DOI：
10.1016/j.apcatb.2017.08.031
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Shen Meiqing
中科院分区：
文献类型：
--
作者：
Xu Minhong;Wang Jun;Yu Tie;Wang Jianqiang;Shen Meiqing
Cu/SAPO-34 is a promising NH3-SCR catalyst and its precise preparations involving ammonia exchange, copper loading and copper distribution are still the challenges in exchange procedure of SAPO-34 support. In the present work, a new series of x-NH4-SAPO samples prepared by controlling NH3adsorption temperature (x standed for NH3adsorption temperature) were used to examine their impacts on the following Cu exchange compared with NH4-SAPO-34 by traditional liquid exchange. The TPD and DRIFTS experiments revealed that the NH4+amounts on x-NH4-SAPO samples increased with the NH3adsorption temperature decreasing. And 200-NH4-SAPO prepared by gas NH3adsorption (GA) under 200 °C contained the similar NH4+loading with L-NH4-SAPO prepared by the liquid ion exchange (LIE) method, but they presented different coordinations between NH4+species and Sisingle bond(OH)single bondAl. After copper exchange, the H2-TPR and EPR results unveiled monodentate NH4+on Sisingle bond(OH)single bondAl structure would facilitate isolated Cu2+generation in Cu/SAPO-34, while the polydentate NH4+would promote CuO formationvialiquid Cu ion exchange. Therefore, it was found that the isolated Cu2+content in 200-Cu-SAPO was lower than L-Cu-SAPO even under the same copper exchange condition for different NH4+coordinations. In addition, theex-situIR and NMR results demonstrated that the Sisingle bondOsingle bondAl bonds without NH4+protections unveiled bond breakage during the liquid Cu exchange. Finally, our study proposed NH4+exchange mechanism on Brønsted acid sites in NH4-SAPO-34 and indicated their influences on the copper distribution and the support integrity for x-Cu-SAPO catalysts.
