DeNOx of Exhaust Gas from Lean-Burn Engines through Reversible Adsorption of N2O3 in Alkali Metal Cation Exchanged Faujasite-Type Zeolites

Sultana, Asima; Loenders, Raf; Monticelli, Orietta; Kirschhock, Christine; Jacobs, Pierre; Martens, Johan A.

doi:10.1002/1521-3773(20000818)39:16<2934::aid-anie2934>3.0.co;2-e

Cited by 53 publications

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“…Neutron‐ and X‐ray‐diffraction techniques revealed the presence of guest molecules interacting with the sodium ions, which results in a reorganization of the cation distribution 1a. 3a,3b The presence of water molecules in the structure has a strong impact on position and occupation numbers of sodium atoms 5. 4a,b,c Exposure of Na–Y zeolite to a gas mixture containing 5–10 % water at 250 °C results in a water content of 50–60 water molecules per unit cell 5.…”

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confidence: 99%

“…3a,3b The presence of water molecules in the structure has a strong impact on position and occupation numbers of sodium atoms 5. 4a,b,c Exposure of Na–Y zeolite to a gas mixture containing 5–10 % water at 250 °C results in a water content of 50–60 water molecules per unit cell 5. These water molecules interact with the sodium ions of the host to form a complex water–cation structure.…”

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Adsorption Chemistry of Sulfur Dioxide in Hydrated Na–Y Zeolite

et al. 2004

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Na-Y is one of the oldest known synthetic zeolite materials. Like zeolite X, it has the faujasite framework topology. The framework structure of zeolites Na-X and Na-Y extensively was studied by diffraction methods [1a,b] and the positions of exchangeable cations in dehydrated faujasites are well documented.[1c]Positions and occupation numbers of sodium cations in Na-Y dehydrated by evacuation [2a,b] and drying in gas streams [2c] were derived by solid-state NMR spectroscopy. Neutron-and X-ray-diffraction techniques revealed the presence of guest molecules interacting with the sodium ions, which results in a reorganization of the cation distribution. [1a, 3a,3b] The presence of water molecules in the structure has a strong impact on position and occupation numbers of sodium atoms. [5, 4a,b,c] Exposure of Na-Y zeolite to a gas mixture containing 5-10 % water at 250 8C results in a water content of 50-60 water molecules per unit cell.[5] These water molecules interact with the sodium ions of the host to form a complex water-cation structure. The water-sodium arrangement consists of chains of alternating SV and SIII cations, bridged by water molecules. Additional water molecules associated with cations on SII positions stabilize this structure. When nitrogen oxides are present, these can reversibly be inserted into the water-cation net as N 2 O 3

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Adsorption Chemistry of Sulfur Dioxide in Hydrated Na–Y Zeolite

et al. 2004

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“…However, addition of a controlled amount of water forces the radicals to depart into the alkane liquid surrounding the zeolite crystal, and this allows to start alkane autoxidation at clearly lower temperatures than in an uncatalyzed process [36]. Another unexpected observation was that Na-Y zeolite is an excellent adsorbent for NO x [37,38]. NO x can be trapped as an N 2 O 3 molecule in the faujasite cages, at a specific location in the network of sodium ions and water molecules (Fig.…”

Section: Redox Catalysis With Transition Metal Ion Exchanged Faujasitesmentioning

confidence: 84%

Forty Years of Designing Catalytic and Adsorptive Sites in FAU Type Zeolites at K.U. Leuven

Martens¹,

Vos²,

Kirschhock³

et al. 2009

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An overview of scientific achievements at K.U. Leuven on the design and characterization of active sites in X and Y zeolites and on the development of adsorptive and catalytic processes in which these active sites are operated is provided. The historical development of this research area and the scientific progress are presented. Zeolite Y and ultrastabilized specimen present Brønsted and Lewis sites that can be operated in vapor and liquid phase hydrocarbon conversion processes, bifunctional catalysis, epoxidation and ring opening of epoxides. Examples of molecular shape selective catalysis with Y zeolites are presented. The redox chemistry of transition metal exchanged faujasites is understood in great detail and has been exploited in Wacker chemistry and water splitting in a photochemicalthermal cycle. Selective adsorbents were designed based on knowledge of cation siting in X and Y zeolites. The occlusion of coordination compounds in the faujasite supercages is a means of creating unique active sites. Catalytic oxidative properties of the enzymes can be mimicked by embedding zeozyme in a hydrophobic membrane.

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“…Potential NO x adsorbents include transition metal oxides, [10] hydrotalcite-like compounds, [11,12] perovskites, [13,14] activatied carbon, [15] α-FeOOH dispersed on activated carbon fibers, [16,17] Pt-Ba/γ-Al 2 O 3 [18] and Pt/K/γ-Al 2 O 3 [19] . [24] And the NO x adsorption capacity for metal ion-exchanged Y-type zeolites decreased in the order of Ba-Y＞Cs-Y＞Na-Y＞Li-Y. [20][21][22][23][24][25][26][27] Iwamoto et al [22] prepared a series of metal ion-exchanged ZSM-5 zeolites, and found that copper ion-exchanged ZSM-5 zeolites showed great ability for reversible adsorption of NO at 273 K. Kröcher et al [23] discovered adsorption capacity for NO 2 was stronger than that for NO adsorption on Cu-ZSM-5 zeolites and the presence of water in the feed decreased its adsorption capacity for NO 2 .…”

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confidence: 99%

Superior Storage Performance for NO in Modified Natural Mordenite

Wang

Xiao

et al. 2012

Chin. J. Chem.

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Natural mordenite (NMOR), modified by acid treatment and ion-exchange, was employed for NO adsorption in the present study. The NO storage capacity of modified NMOR was greatly improved compared with its original correspondents, mainly due to the preservation of crystalline structure and the improvement of surface area of NMOR. Among all the modified NMOR, Ni-NMOR exhibited the highest adsorption capacity for NO (1.20 mmol•g -1 ) in the presence of 10% O 2 at 308 K. The influence of the main ingredients in flue gas on the storage capacity of NMOR for NO had also been investigated. In general, H 2 O, CO 2 and SO 2 all displayed negative impact on NO adsorption due to their competitive adsorption on the surface of NMOR with NO, while the presence of O 2 greatly improved the adsorption of NO because of the formation of NO 2 and N 2 O 3 . Moreover, Ni-NMOR exhibited high efficiency for NO x removal through the NO x adsorption-plasma discharge process.

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DeNOx of Exhaust Gas from Lean-Burn Engines through Reversible Adsorption of N2O3 in Alkali Metal Cation Exchanged Faujasite-Type Zeolites

Cited by 53 publications

References 16 publications

Adsorption Chemistry of Sulfur Dioxide in Hydrated Na–Y Zeolite

Adsorption Chemistry of Sulfur Dioxide in Hydrated Na–Y Zeolite

Forty Years of Designing Catalytic and Adsorptive Sites in FAU Type Zeolites at K.U. Leuven

Superior Storage Performance for NO in Modified Natural Mordenite

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