Chen Jialing, Peng Gang, Liang Tingyu, Zhang Wenbo, Zheng Wei, Zhao Haoran, Guo Li, Wu Xiaoqin
Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials, School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, China.
Key Laboratory for Green Chemical Process of Ministry of Education, and Hubei Key Laboratory of Novel Reactor & Green Chemical Technology, School of Chemical Engineering & Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China.
Nanomaterials (Basel). 2020 Oct 30;10(11):2170. doi: 10.3390/nano10112170.
The NH-SCR activities and hydrothermal stabilities of five Cu/MCM-22 zeolites with different Cu loadings ( = 2-10 wt%) prepared by incipient wetness impregnation method were systematically investigated. The physicochemical properties of Cu/MCM-22 zeolites were analyzed by XRD, nitrogen physisorption, ICP-AES, SEM, NH-TPD, UV-vis, H-TPR and XPS experiments. The Cu species existing in Cu/MCM-22 are mainly isolated Cu, CuO and unreducible copper species. The concentrations of both isolated Cu and CuO species in Cu/MCM-22 increase with Cu contents, but the increment of CuO species is more distinct, especially in high Cu loadings (>4 wt%). NH-SCR experimental results demonstrated that the activity of Cu/MCM-22 is sensitive to Cu content at low Cu loadings (≤4 wt%). When the Cu loading exceeds 4 wt%, the NH-SCR activity of Cu/MCM-22 is irrelevant to Cu content due to the severe pore blockage effects caused by aggregated CuO species. Among the five Cu/MCM-22 zeolites, 4Cu/MCM-22 with moderate Cu content has the best NH-SCR performance, which displays higher than 80% NO conversions in a wide temperature window (160-430 °C). Furthermore, the hydrothermal aging experiments (Cu/MCM-22 was treated at 750 °C for 10 h under 10% water vapor atmosphere) illustrated that all the Cu/MCM-22 zeolites exhibit high hydrothermal stability in NH-SCR reactions.
通过初湿浸渍法制备了五种不同铜负载量（2-10 wt%）的Cu/MCM-22分子筛，系统研究了其NH-SCR活性和水热稳定性。通过XRD、氮气物理吸附、ICP-AES、SEM、NH-TPD、UV-vis、H-TPR和XPS实验对Cu/MCM-22分子筛的物理化学性质进行了分析。Cu/MCM-22中存在的铜物种主要为孤立的Cu、CuO和不可还原的铜物种。Cu/MCM-22中孤立Cu和CuO物种的浓度均随铜含量的增加而增加，但CuO物种的增加更为明显，尤其是在高铜负载量（>4 wt%）时。NH-SCR实验结果表明，在低铜负载量（≤4 wt%）下，Cu/MCM-22的活性对铜含量敏感。当铜负载量超过4 wt%时，由于聚集的CuO物种导致严重的孔堵塞效应，Cu/MCM-22的NH-SCR活性与铜含量无关。在五种Cu/MCM-22分子筛中，铜含量适中的4Cu/MCM-22具有最佳的NH-SCR性能，在较宽的温度窗口（160-430°C）内显示出高于80%的NO转化率。此外，水热老化实验（Cu/MCM-22在10%水蒸气气氛下于750°C处理10 h）表明，所有Cu/MCM-22分子筛在NH-SCR反应中均表现出高水热稳定性。
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