In situ DRIFTS-MS studies on the oxidation of adsorbed NH3 by NOx over a Cu-SSZ-13 zeolite
In situ DRIFTS-MS studies on the oxidation of adsorbed NH3 by NOx over a Cu-SSZ-13 zeolite
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DOI：
10.1016/j.cattod.2012.08.043
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发表时间：
2013-04
期刊：
影响因子：
5.3
通讯作者：
Haiyang Zhu;J. Kwak;C. Peden;J. Szanyi
中科院分区：
文献类型：
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作者：
Haiyang Zhu;J. Kwak;C. Peden;J. Szanyi
采用漂移FT光谱结合质谱研究了NO2、NO+ O2和NO2+ O2在铜离子交换的SSZ-13（Cu-SSZ-13）分子筛上对吸附态氨的氧化作用。与NO2和NO相比，Cu-SSZ-13分子筛对NH3的吸附更强。在本文研究的Cu-SSZ-13沸石上发现了两种吸附的氨物种，特别是在布朗斯台德酸位点（质子）上的氨和在刘易斯酸位点（铜离子）上的氨。在NH3氧化过程中，这些吸附的氨物种呈现出不同的活性曲线和对N2的选择性。所获得的结果表明，在Cu-SSZ-13中吸附到铜离子上的氨在低温下比质子吸附的NH3更活跃，并且产生对N2的更高选择性。N2 O的形成主要与NOx与质子吸附的NH3反应生成NH 4 NO3并随后热分解有关。
DRIFT spectroscopy combined with mass spectrometry was used to investigate the oxidation of adsorbed ammonia by NO2, NO+O2and NO2+O2on a copper ion exchanged SSZ-13 (Cu-SSZ-13) zeolite. Compared with both NO2and NO, the adsorption of ammonia is much stronger on the Cu-SSZ-13 zeolite. Two adsorbed ammonia species were found over the Cu-SSZ-13 zeolite studied here, notably ammonia on Brønsted acid sites (proton) and ammonia on Lewis acid sites (copper ions). These adsorbed ammonia species present different activity profiles and selectivity to N2during NH3oxidation. The results obtained suggest that ammonia adsorbed onto copper ions in Cu-SSZ-13 is more active at low temperatures than proton-adsorbed NH3, and give rise to a higher selectivity to N2. The formation of N2O is associated primarily with the reaction of NOxwith proton-adsorbed NH3via the formation and subsequent thermal decomposition of NH4NO3.