NOx adsorption complexes on zeolites containing metal cations and strong lewis acid sites and their reactivity in CO and CH4 oxidation: A spectroscopic study

Kustov, L. М.; Smekalina, E.V.; Uvarova, E.B.; Kazansky, V.B.

doi:10.1016/s0167-2991(06)81915-4

Cited by 4 publications

(5 citation statements)

References 9 publications

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“…Figure 2 presents IR spectra measured after adsorption of NO at 20 °C on NaY and Ca-Y zeolites. These spectra are similar to the earlier observed spectra of NO adsorbed on Na- and Ca-forms of different zeolites [ 6 , 35 ].…”

Section: Resultssupporting

confidence: 90%

IR-Spectroscopic Study of Complex Formation of Nitrogen Oxides (NO, N2O) with Cationic Forms of Zeolites and the Reactivity of Adsorbed Species in CO and CH4 Oxidation

Kustov

Кustov

2021

Molecules

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The formation of complexes and disproportionation of nitrogen oxides (NO, N2O) on cationic forms of LTA, FAU, and MOR zeolites was investigated by diffuse-reflectance IR spectroscopy. N2O is adsorbed on the samples under study in the molecular form and the frequencies of the first overtone of the stretching vibrations ν10–2 and the combination bands of the stretching vibrations with other vibrational modes for N2O complexes with cationic sites in zeolites (ν30–1 + ν10–1, ν10–1 + δ0–2) are more significantly influenced by the nature of the zeolite. The presence of several IR bands in the region of 2400–2600 cm−1 (the ν10–1 + δ0–2 transitions) for different zeolite types was explained by the availability of different localization sites for cations in these zeolites. The frequencies in this region also depend on the nature of the cation (its charge and radius). The data can be explained by the specific geometry of the N2O complex formed, presumably two-point adsorption of N2O on a cation and a neighboring oxygen atom of the framework. Adsorption of CO or CH4 on the samples with preliminarily adsorbed N2O at 20–180 °C does not result in any oxidation of these molecules. NO+ and N2O3 species formed by disproportionation of NO are capable of oxidizing CO and CH4 molecules to CO2, whereas NOx is reduced simultaneously to N2 or N2O. The peculiarities in the behavior of cationic forms of different zeolites with respect to adsorbed nitrogen oxides determined by different density and localization of cations have been established.

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Section: Resultssupporting

confidence: 90%

IR-Spectroscopic Study of Complex Formation of Nitrogen Oxides (NO, N2O) with Cationic Forms of Zeolites and the Reactivity of Adsorbed Species in CO and CH4 Oxidation

Kustov

Кustov

2021

Molecules

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“…4, No. 3;2012 close to the difference in the NOx-conversion temperature between both catalysts. The thermal energies required for the de-NOx reactions at lower light-off temperatures are supplied by the exothermic reactions, such as oxidations of NO and the HCs.…”

Section: The Support Effect From a Kinetic View Pointsupporting

confidence: 52%

“…4, No. 3;2012 and N 2 O contained in the effluent gas through an online-system. The result was analyzed based on the experimental NOx-conversions and NO:NO 2 ratios.…”

Section: Measurement Of Nox-conversionsmentioning

confidence: 99%

“…4, No. 3;2012 Obviously, the MPS and metal-silicate supports produce the catalyst low-temperature activity, while γ-alumina produces the high-temperature activity. The average Pt-particle sizes of the Pt/MPS and Pt/γ-alumina are the same at 2 nm.…”

Section: Heat Resistance Of Pt/mpsmentioning

confidence: 99%

“…Among the zeolites, the addition of moldenite and erionite increased the NOx-conversions in the range of 170-300 , but were only slightly effective below 170 . Around the same time as the discovery of HC-SCR of NOx over Cu-Zeolites, classical work for determining the active-sites of zeolites reported that the complex formation and transformation of nitrogen oxides (NO and N 2 O) with cations and strong Lewis acid sites in zeolites (ZSM-5, MOR, LTA and FAU) yield strong NO δ+ and N 2 O 3 species to oxidize CO and CH 4 into CO 2 (Kustov et al, 1995 (Sherry, 2003). Accordingly, the effects of the zeolites used as additives are presumably due to the adsorption of HCs but not due to the adsorption of NO 2 similar to LNT (Lean-NOx-Trap).…”

Section: The Support Effect On Nox-conversion Vs Temperature Profilementioning

confidence: 99%

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Low-Temperature Active Pt-catalysts Supported on Mesoporous Silica and Metal-Silicates for Cleaning Diesel-NOx Exhausts

Komatsu¹,

Tomokuni²,

Konishi³

et al. 2012

IJC

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New Pt-catalysts supported on mesoporous silica (MPS) and metal-silicates, which have high de-NOx capabilities over 70 % in NOx-conversion at temperatures around 170 under lean conditions, were developed. A new prototype honeycomb supporting Pt-catalyst allows high de-NOx of diesel-exhausts possible over the wide temperature range of 170-400 . The low-temperature activities of the catalysts are well correlated with the Brønsted acidity of the support materials. In view of the reaction mechanism of the de-NOx processes, the Brønsted acid-sites of the supports probably stimulate the oxidation of NO into NO 2 , which is the rate-determining step of de-NOx processes, leading to the low-temperature activities.

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Competitive adsorption of N2O and CO on CuZSM-5, FeZSM-5, CoZSM-5 and bimetallic forms of ZSM-5 zeolite

et al. 2005

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NOx adsorption complexes on zeolites containing metal cations and strong lewis acid sites and their reactivity in CO and CH4 oxidation: A spectroscopic study

Cited by 4 publications

References 9 publications

IR-Spectroscopic Study of Complex Formation of Nitrogen Oxides (NO, N2O) with Cationic Forms of Zeolites and the Reactivity of Adsorbed Species in CO and CH4 Oxidation

IR-Spectroscopic Study of Complex Formation of Nitrogen Oxides (NO, N2O) with Cationic Forms of Zeolites and the Reactivity of Adsorbed Species in CO and CH4 Oxidation

Low-Temperature Active Pt-catalysts Supported on Mesoporous Silica and Metal-Silicates for Cleaning Diesel-NOx Exhausts

Competitive adsorption of N2O and CO on CuZSM-5, FeZSM-5, CoZSM-5 and bimetallic forms of ZSM-5 zeolite

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