FTIR Spectroscopic Study of Low Temperature NO Adsorption and NO + O2 Coadsorption on H-ZSM-5

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• 作者：A. Penkova ; K. Hadjiivanov ; M. Mihaylov ; M. Daturi ; J. Saussey ; and J.-C. Lavalley
• 刊名：Langmuir
• 出版年：2004
• 出版时间：June 22, 2004
• 年：2004
• 卷：20
• 期：13
• 页码：5425 - 5431
• 全文大小：162K
• 年卷期：v.20,no.13(June 22, 2004)
• ISSN：1520-5827

文摘

Adsorption of NO and coadsorption of NO and O₂ on H-ZSM-5 have been studied at low and roomtemperature by means of FTIR spectroscopy. For better interpretation of the spectra, experiments involvingisotopic labeled molecules have been performed. Low temperature adsorption of NO on H-ZSM-5 resultsinitially in formation of NO which is H-bonded to the zeolite acidic hydroxyls. A second NO molecule isinserted into the OH-NO species at higher coverages, thus forming OH(NO)₂ complexes. Different kindsof NO dimers are also formed. Negligible amounts of oxygenated compounds have been detected. In thepresence of oxygen, the (di)nitrosyl species are oxidized very fast even at 100 K to N₂O₃, NO⁺, NO₂, andN₂O₄. Different kinds of adsorbed N₂O₃ species have been evidenced. With increasing temperature, NO⁺migrates and occupies cationic positions. The latter species interacts with NO at low temperature to givean [ONNO]⁺ complex. This reaction is used to prove that the different bands in the 2206-2180 cm^-1 regionare also due to NO⁺ species.