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- Title
Low-temperature activation of nitrogen oxide on Cu-ZSM-5 catalysts.
- Authors
Yashnik, S.; Anufrienko, V.; Sazonov, V.; Ismagilov, Z.; Parmon, V.
- Abstract
The adsorption and activation of NO molecules on Cu-ZSM-5 catalysts with different Cu/Al and Si/Al ratios (from 0.05 to 1.4 and from 17 to 45, respectively) subjected to different pretreatment was studied by ultraviolet-visible diffuse reflectance (UV-Vis DR). It was found that the amount of chemisorbed NO and the catalyst activity in NO decomposition increased with an increase in the Cu/Al ratio to 0.35-0.40. The intensity of absorption bands at 18400 and 25600 cm in the UV-Vis DR spectra increased symbatically. It was hypothesized that the adsorption of NO occurs at Cu ions localized in chain copper oxide structures with the formation of mono- and dinitrosyl Cu(I) complexes, and this process is accompanied by the Cu...Cu intervalence transfer band in the region of 18400 cm. The low-temperature activation of NO occurs through the conversion of the dinitrosyl Cu(I) complex into the π-radical anion (NO) stabilized at the Cu ion of the chain structure, [Cu- cis-(NO)], by electron transfer from the Cu ion to the cis dimer (NO). This complex corresponds to the L → M charge transfer band in the region of 25600 cm. The subsequent destruction of the complex [Cu- cis-(NO)] at temperatures of 150-300°C leads to the release of NO and the formation of the complex [CuO], which further participates in the formation of the nitrite-nitrate complexes [Cu(NO)], [Cu(NO)(NO)], and [Cu(NO)] and NO decomposition products.
- Subjects
NITROGEN oxides; CATALYST supports; LOW temperatures; NITROGEN oxide absorption &; adsorption; CATALYTIC activity; CHEMICAL decomposition; CHEMICAL stability; CHARGE transfer
- Publication
Kinetics & Catalysis, 2012, Vol 53, Issue 3, p363
- ISSN
0023-1584
- Publication type
Article
- DOI
10.1134/S0023158412030135