Comparison study of Na poisoning effect on copper-based chabazite micropore catalysts for NH3-SCR reaction |
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| Authors: | WANG Chen CHEN Zexiang WANG Jianqiang SHEN Meiqing WANG Jun |
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| Affiliation: | 1.School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China;2.School of Environmental and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China;3.State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China |
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| Abstract: | Using wet impregnation method to mimic alkali metal poison of ammonia-selective catalytic reduction (NH3-SCR) catalysts, Cu-based micropore zeolites Cu/SSZ-13 and Cu/SAPO-34 with different Na contents(mass fraction) were prepared, and the Na poisoning mechanism on them was studied. The results show that the externally introduced Na ions can severely affect the NH3-SCR catalytic activity of the two catalysts, resulting in the collapse of the crystal structure of the catalyst, the decrease of acidity and the reduction of active species. In detail, when Na content was less than 1.82%, Cu/SAPO-34 has higher resistance of Na ions than Cu/SZZ-13; while when Na> 3.48%, Cu/SAPO-34 catalysts almost deactivated thoroughly. By structural characterization (BET, XRD and SEM) and acidity characterization (DRIFTS, NH3-TPD and H2-TPR), it was found that with Na poisoning deeper and deeper, Cu/SSZ-13 took a gradual style of the structural destruction, but Cu/SAPO-34 adopted a sudden way. Studies on the mechanism of Na poisoning show that the decrease of acid sites is the main reason for the decrease of SCR activity of Cu/SSZ-13, and the structural collapse is the main reason for the decrease of SCR activity of Cu/SAPO-34. |
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| Keywords: | selective catalytic reduction alkali metal zeolite catalysts nitric oxide poison mechanism |
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