Abstract:Cu-SSZ-13 and CuO/SSZ-13 catalysts were prepared by ion exchange and impregnation methods, respectively and tested for selective catalytic oxidation of NH3 (NH3-SCO). Cu-SSZ-13(2) catalyst, which was prepared by ion exchange for two times, performed the best in improving NH3 conversion and N2 selectivity at low temperatures (£200℃). Effects of O2 content and gas hourly space velocity (GHSV) on the oxidation of NH3 over Cu-SSZ-13(2) were investigated. Physicochemical characteristics of the catalysts and the surface reaction process were characterized by N2 adsorption-desorption, XRD, NH3-TPD and NH3-TPSR techniques. The results showed that NH3 conversion and N2 selectivity reached 98.5% and 92.2%, respectively at 200℃ over Cu-SSZ-13(2). With the increase of O2 content, NH3 conversion at low temperatures increased, but N2 selectivity decreased. With the increase of GHSV, NH3 conversion at low temperatures decreased, but N2 selectivity was hardly affected. Low N2 selectivity for NH3 oxidation at low temperatures (£200℃) over Cu-SSZ-13 and CuO/SSZ-13 was mainly due to the formation of N2O by-product. Compared with CuO/SSZ-13, Cu-SSZ-13(2) had larger values of specific surface area, pore volume and pore size, less CuO and more Lewis and Brønsted acid sites on the surface, which might explain the higher NH3 conversion and N2 selectivity obtained at low temperatures over Cu-SSZ-13(2). Apart from N2O, NO and NO2 by-products were also detected during the NH3-TPSR process over Cu-SSZ-13(2). It could be inferred that NH3-SCO over Cu-SSZ-13(2) followed the internal selective catalytic reduction (iSCR) mechanism considering the fact that NO and NO2 selectivity increased with the increase of GHSV at low temperatures.
陈莉, 樊星, 李佳, 张玮航, 李坚. 制备方法对SSZ-13负载Cu催化剂NH3-SCO性能的影响[J]. 中国环境科学, 2023, 43(7): 3378-3386.
CHEN Li, FAN Xing, LI Jia, ZHANG Wei-hang, LI Jian. Effect of preparation methods on NH3-SCO performance of SSZ-13 supported Cu catalysts. CHINA ENVIRONMENTAL SCIENCECE, 2023, 43(7): 3378-3386.
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