Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

Giordanino, Filippo; Vennestrøm, Peter N. R.; Lundegaard, L. F.; Stappen, Frederick N.; Mossin, Susanne; Beato, Pablo; Bordiga, Silvia; Lamberti, Carlo

doi:10.1039/c3dt50732g

Cited by 340 publications

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“…[25] The spectral features agree well with the isolated octahedral copper complexes observed in zeolites, in which the surrounding ligands are water or hydroxyl groups. [16,29,30] This result implies that all the Cu-SSZ-13 samples contain predominantly isolated copper species, which is in accordance with the work of Lamberti et al [31] On the basis of the results of extended X-ray absorption fine structure and UV/Vis spectroscopy, Beale et al proposed that isolated Cu 2 + is the active site for the NH 3 -SCR reaction. [20][21][22] The EPR spectra of OP-0.37 and IE-0.36 samples demonstrate the same features (Figure 3 a and b).…”

Section: Resultssupporting

confidence: 78%

“…Furthermore, the overall intensity of the EPR spectra decreased significantly if the samples were dehydrated before the measurement because Cu 2 + species are autoreduced to Cu + species. This explanation was discarded earlier by Lamberti et al [31] These authors put forward, as the most reasonable explanation, that the loss of EPR intensity is due to a change in the coordination environment (water is removed, and the interaction of Cu 2 + ions with the oxygen anions of the zeolite increase). We refer to the work of Lamberti et al for relevant explanations for the change in the EPR spectra.…”

Section: Resultsmentioning

confidence: 92%

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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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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 92%

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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“…4). Note that we observed no bands in the region 1728-1810 cm −1 , indicating that no Cu + species were present in our conditions [6,16]. Two main bands appear at wavenumbers of 1904-1911 and 1947-1949 cm −1 , as well as a smaller shoulder at approximately 1930 cm −1 .…”

Section: No-driftsmentioning

confidence: 95%

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

et al. 2017

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“…27 The measurement of the NO conversion was done in a microreactor, using a 5 mg sample of the Cu-CHA catalyst (sieve fraction 150-300 µm) in a quartz U-tube reactor with 2 mm inner diameter. The composition of the reactor exit gas was determined using a Gasmet CX400 FTIR spectrometer connected to the outlet of the reactor.…”

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A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

et al. 2015

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For the first time, the standard and fast selective catalytic reduction (SCR) of NO by NH3 are described in a complete catalytic cycle that is able to produce the correct stoichiometry while allowing adsorption and desorption of stable molecules only. The standard SCR reaction is a coupling of the activation of NO by O2 with the fast SCR reaction, enabled by the release of NO2. According to the scheme, the SCR reaction can be divided into an oxidation of the catalyst by NO + O2 and a reduction by NO + NH3; these steps together constitute a complete catalytic cycle. Furthermore, both NO and NH3 are required in the reduction, and finally, oxidation by NO + O2 or NO2 leads to the same state of the catalyst. These points are shown experimentally for a Cu-CHA catalyst by combining in situ X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and Fourier transform infrared spectroscopy (FTIR). A consequence of the reaction scheme is that all intermediates in fast SCR are also part of the standard SCR cycle. The activation energy calculated by density functional theory (DFT) indicates that the oxidation of an NO molecule by O2 to a bidentate nitrate ligand is rate-determining for standard SCR. Finally, the role of a nitrate/nitrite equilibrium and the possible influence of Cu dimers and Brønsted sites are discussed, and an explanation is offered as to how a catalyst can be effective for SCR while being a poor catalyst for NO oxidation to NO2.

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Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

Cited by 340 publications

References 140 publications

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

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

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

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