Effects of hydrothermal aging on NH3-SCR reaction over Cu/zeolites

Kwak, Ja Hun; Tran, Diana; Burton, Sarah D.; Szanyi, János; Lee, Jong H.; Peden, Charles H. F.

doi:10.1016/j.jcat.2011.12.025

Cited by 458 publications

(225 citation statements)

References 13 publications

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“…It can be expected that such a process depends on temperature, aging time and Cu loading, where higher aging temperatures, longer aging durations and higher Cu loadings promote more damage. Prior literature is fully in line with this structure damage mechanism [39][40][41]53,61] On the other hand, dealumination alone is apparently much less destructive for this zeolite catalyst.…”

Section: Towards Rational Design Of Cu/ssz-13supporting

confidence: 55%

“…Hydrothermal stability of Cu/SSZ-13 is a critical criterion for its practical applications; as such, hydrothermal aging effects have been extensively addressed [29,37,[39][40][41]. Hydrothermal stability depends on various parameters including catalyst composition, aging temperature and duration.…”

Section: Hydrothermal Agingmentioning

confidence: 99%

“…In contrast, hydrothermal degradation is typically irreversible due to permanent structural changes in the zeolite that result in, for example, loss of Brønsted acid sites and changes to the chemical or physical structure of Cu active centers. This explains why hydrothermal aging effects have been so extensively studied [39][40][41][52][53][54]. Prior studies have suggested that Cu/SSZ-13 durability enhancement can be achieved in a number of ways: (1) composition optimization, that is, choosing optimized Si/Al and Cu/Al ratios [31]; (2) zeolite particle size optimization [55]; (3) new synthesis methods development [30,[56][57][58][59]; and (4) introduction of stability enhancement additives.…”

Section: Towards Rational Design Of Cu/ssz-13mentioning

confidence: 99%

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Recent Progress in Atomic-Level Understanding of Cu/SSZ-13 Selective Catalytic Reduction Catalysts

Gao

Peden

2018

Catalysts

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Cu/SSZ-13 Selective Catalytic Reduction (SCR) catalysts have been extensively studied for the past five-plus years. New and exciting fundamental and applied science has appeared in the literature quite frequently over this time. In this short review, a few topics specifically focused on a molecular-level understanding of this catalyst are summarized: (1) The nature of the active sites and, in particular, their transformations under varying reaction conditions that include dehydration, the presence of the various SCR reactants and hydrothermal aging; (2) Discussions of standard and fast SCR reaction mechanisms. Considerable progress has been made, especially in the last couple of years, on standard SCR mechanisms. In contrast, mechanisms for fast SCR are much less understood. Possible reaction paths are hypothesized for this latter case to stimulate further investigations; (3) Discussions of rational catalyst design based on new knowledge obtained regarding catalyst stability, overall catalytic performance and mechanistic catalytic chemistry.

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Section: Towards Rational Design Of Cu/ssz-13supporting

confidence: 55%

Section: Hydrothermal Agingmentioning

confidence: 99%

Section: Towards Rational Design Of Cu/ssz-13mentioning

confidence: 99%

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Recent Progress in Atomic-Level Understanding of Cu/SSZ-13 Selective Catalytic Reduction Catalysts

Gao

Peden

2018

Catalysts

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“…It is well known that the key factors determining the activity and selectivity of supported catalysts are the nature and dispersion of copper species, which depend approximately on the aluminum content in the framework and the copper loading ratio [8,9]. Many researches demonstrated that the most active catalysts tend to have the lowest Si/Al atomic ratio because only copper ions close to framework AlO4 -are active in the decomposition of NO into N2 [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Cerium doped copper/ZSM-5 catalysts used for the selective catalytic reduction of nitrogen oxide with ammonia

Dou

Wang

et al. 2015

Chemical Engineering Journal

124

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Abstract:The CuCe/ZSM-5 catalysts with different cerium loadings (0, 0.5, 1.0, 1.5 and 2.0 wt.%) was investigated to evaluate the correlation between structural characteristics and catalytic performance for the selective catalytic reduction (SCR) of NO by NH3. It was found that the addition of cerium increased copper dispersion and prevented its crystallization. According to the results of X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction by hydrogen (H2-TPR), copper species were enriched on the ZSM-5 grain surfaces and part of copper ions was incorporated into the cerium lattice. Addition of cerium improved the redox properties of the CuCe/ZSM-5 catalysts, owing to the higher valence of copper and mobility of lattice oxygen than those of Cu/ZSM-5 catalyst. Hence the introduction of * Corresponding author. Tel.: +86-22-60601278; Fax.: +86-22-60600320 E-mail address: haoqinglan@tust.edu.cn ** Corresponding author. Tel.: +822 2220 0441; fax: +822 2220 2299 (K. Hui)E -mail address: kshui@hanyang.ac.kr (K. Hui) 2 cerium in Cu/ZSM-5 improved significantly NO conversion. On the one hand, the cerium introduction into Cu-Z enhances their low-temperature activities. 95% NO conversion is reached around 197 ºC for Cu-Z while the corresponding temperature value decreases to 148 ºC for CuCe4-Z. On the other hand, the temperature range of efficient NO reduction (95%) also extends to higher temperature when the cerium are added to Cu/ZSM-5. Among the Cu-Ce/ZSM-5 catalysts tested, the CuCe4-Z sample exhibits the highest catalytic activity with the temperature range for 90% NO removal of 148-427 ºC.

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“…[7,[9][10][11] The ion-exchanged copper-containing SSZ-13 zeolite, based on the small-pore chabazite (CHA) zeolite topology, recently demonstrated higher activity and selectivity to N 2 over a wide temperature range and better hydrothermal stability than did Cu/ ZSM-5 and Cu/BEA zeolites. [12][13][14][15][16][17] Typically, the catalytic SCR performance of the copper-containing zeolite greatly depends on the location and nature of copper species. The existence of various types of copper species in the zeolite has been proposed: Cu 2 + and Cu + monomers, [CuÀOÀCu] 2 + dimers, and CuO x clusters.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Nature and Location of Copper Species on the Catalytic Nitric Oxide Selective Catalytic Reduction Performance of the Copper/SSZ‐13 Zeolite

et al. 2013

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. (2014). Effect of the nature and location of copper species on catalytic nitric oxide selective catalytic reduction performance of the copper/SSZ-13 zeolite. ChemCatChem, 6(2), 634-639. DOI: 10.1002/cctc.201300775 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. [b] Guanna Li, [a, b] Zhaochi Feng, [a] Emiel J. M. Hensen,* [b] and Can Li*[a] IntroductionThe selective catalytic reduction (SCR) of nitrogen oxides (NO x ) with ammonia (NH 3 -SCR) is an efficient way for NO x abatement. [1][2][3] Copper-containing zeolites are one of the most active catalyst systems for the related reactions. [3][4][5][6][7][8] The most extensive studies have been performed on Cu/ZSM-5 and Cu/ BEA zeolites. Cu/BEA demonstrates excellent activity with better hydrothermal stability than does Cu/ZSM-5. [7,[9][10][11] The ion-exchanged copper-containing SSZ-13 zeolite, based on the small-pore chabazite (CHA) zeolite topology, recently demonstrated higher activity and selectivity to N 2 over a wide temperature range and better hydrothermal stability than did Cu/ ZSM-5 and Cu/BEA zeolites. [12][13][14][15][16][17] Typically, the catalytic SCR performance of the copper-containing zeolite greatly depends on the location and nature of copper species. The existence of various types of copper species in the zeolite has been proposed: Cu 2 + and Cu + monomers, [CuÀOÀCu] 2 + dimers, and CuO x clusters. [17][18][19] Isolated Cu 2 + species are usually postulated as the active sites in the SCR reaction. [20][21][22] The preparation method strongly affects the nature and speciation of the copper phase. In general, monomeric copper ions located at the cation-exchange sites dominate in ion-exchanged samples, with the fraction of [CuÀOÀ Cu] 2 + dimers typically becoming more important with increasing Cu content. [18] In contrast, precipitation usually results in the formation of a separate CuO phase located at the external zeolite surface. [17][18][19] Lobo et al. suggested that Cu 2 + ions are located in the six-membered rings of the CHA structure. [23] Combining extended X-ray absorption fine structure and in situ UV/Vis spectroscopy, Beale et al. proposed that isolated mononuclear Cu 2 + species slightly shifted toward the edge of the six-membered rings.[20] Kwak et al. reported that the location of ...

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Effects of hydrothermal aging on NH3-SCR reaction over Cu/zeolites

Cited by 458 publications

References 13 publications

Recent Progress in Atomic-Level Understanding of Cu/SSZ-13 Selective Catalytic Reduction Catalysts

Recent Progress in Atomic-Level Understanding of Cu/SSZ-13 Selective Catalytic Reduction Catalysts

Cerium doped copper/ZSM-5 catalysts used for the selective catalytic reduction of nitrogen oxide with ammonia

Effect of the Nature and Location of Copper Species on the Catalytic Nitric Oxide Selective Catalytic Reduction Performance of the Copper/SSZ‐13 Zeolite

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