Interaction of NH3with Cu-SSZ-13 Catalyst: A Complementary FTIR, XANES, and XES Study

Giordanino, Filippo; Borfecchia, Elisa; Lomachenko, Kirill A.; Lazzarini, Andrea; Agostini, Giovanni; Gallo, Erik; Soldatov, A. V.; Beato, Pablo; Bordiga, Silvia; Lamberti, Carlo

doi:10.1021/jz500241m

Cited by 257 publications

(417 citation statements)

References 70 publications

(166 reference statements)

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“…Although the spectrum for CuO x /10A2B at 200°C was also similar to that for CuO, the absorption energy of the XANES spectra for CuO x / 10A2B shifted to lower energy when increasing the combustion temperature to 400°C. Subsequently, the absorption energy of the spectrum for CuO x /10A2B at 600°C exhibited a weak preedge assigned to Cu + 1s ¼ 4p transition, 5) which was observed in the spectrum for Cu 2 O. According to linear combination fitting (Table S1), CuO in CuO x /10A2B at 600°C was reduced approximately 50% to Cu 2 O.…”

Section: ¹1mentioning

confidence: 92%

Operando XAFS studies of supported copper oxides for catalytic ammonia combustion

Hinokuma

Kawabata

Kiritoshi

et al. 2017

J. Ceram. Soc. Japan

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Local structures around copper oxides (CuO x ) supported on aluminum oxide borates (10A2B) during the NH 3 combustion reaction were studied by operando XAFS. Although CuO x in as-prepared CuO x /10A2B at room temperature can be assigned to CuO, the CuO was partly reduced to Cu 2 O during NH 3 combustion at 400°C. In contrast, CuAl 2 O 4 was formed after thermal aging of CuO x /10A2B at 900°C for 100 h in air, local structures of which were preserved during NH 3 combustion at 600°C.©2017 The Ceramic Society of Japan. All rights reserved.Key-words : Operando XAFS, Supported catalysts, Copper oxides, Ammonia combustion [Received March 31, 2017; Accepted May 3, 2017] In order to elucidate the actual dynamics of catalysis, the investigation of the local structures during catalytic reactions is essential. Recently, operando X-ray absorption fine structure (XAFS) measurements have made dramatic progress for use as a powerful technique to study the local structures of catalysts under reaction conditions. 1)12) Kornienko et al. revealed a molecular model of an amorphous cobalt sulfide catalyzing hydrogen evolution reactions by operando XAFS and Raman. 6) Li et al. developed a novel micro-reactor compatible with operando XAFS and scanning transmission electron microscopy (STEM) observation to obtain complex structural dynamics of nanocatalysts.7) Operando XAFS study of metal oxide catalysts during the watergas shift reaction was prospected by Rodriguez et al., who also reported their partial reduction behavior.11) Doronkin et al. elucidated the local structures of iron-and copper-containing zeolites during the selective catalytic reduction (SCR) of NO x by NH 3 , and finally concluded their catalysis and SCR mechanism from the operando XAFS study.3) Therefore, operando XAFS has a great impact on the study of the actual local structures during catalytic reactions as well as the reaction mechanisms.NH 3 has recently been regarded as a renewable and carbon-free energy source due to its high energy density, 13) but it has problems including high ignition temperature and N 2 O/NO x production, in comparison with fossil fuels. Previously, we proposed novel catalytic NH 3 combustion systems that enable low ignition temperatures as well as negligible N 2 O/NO x emissions, 14) 16) and reported that the NH 3 combustion activity of metal oxides increases with a decrease in their metaloxygen bond energy. 14)In addition, a novel catalyst, copper oxide (CuO x ) supported on aluminum oxide borates (10Al 2 O 3 ·2B 2 O 3 : 10A2B) with high performance for NH 3 combustion, was successfully prepared. 15)Although CuO x -based catalysts have also been widely studied for the selective oxidation of NH 3 emissions to reduce air pollution, 17),18) there are no published studies of the catalytic local structures during NH 3 combustion and/or the oxidation reaction over the well-known supported CuO x . Therefore, in this study, the local structures around Cu in the previously developed CuO x / 10A2B and in the conventional CuO x /Al 2 O 3 under ...

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Section: ¹1mentioning

confidence: 92%

Operando XAFS studies of supported copper oxides for catalytic ammonia combustion

Hinokuma

Kawabata

Kiritoshi

et al. 2017

J. Ceram. Soc. Japan

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“…These two locations for the Cu ions are well known from structural analysis of Cu-CHA catalysts, although some controversy exists on which form actually constitutes the active site. 6,12,28,34,[39][40][41]44,52,72,73 However, when adsorbates are present, the Cu ion is lifted out of the 6-ring plane and the preference for the 6-ring location diminishes. 42,43,74 This is also observed for the formation of Cu 2+ −NO 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 (step 1), where the difference in energy for the Cu located in the 8-ring is only 0.08 eV lower compared to the Cu in the 6-ring, showing that there is no real preference for location of the Cu in the 6-ring or 8-ring in this case.…”

Section: Verification Of the Reaction Schemementioning

confidence: 99%

“…In particular, the XANES spectrum measured after reduction in NH 3 + NO (curve b) is characterized by an intense pre-edge peak at ∼ 8983 eV, due to the 1s→4p transitions in Cu + compounds with a low coordination number. 44,76 Furthermore, the weak pre-edge peak at ∼ 8978 eV, which is a fingerprint of the 1s → 3d transition in Cu 2+ , 54,77-81 has disappeared (inset in Figure 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 The FTIR spectra in Figure 4 Following Scheme 1, the reduction of Cu 2+ to Cu + requires both NH 3 and NO. As a consequence, the reduction should result in different states of the Cu, if one of these components is missing.…”

Section: Verification Of the Reaction Schemementioning

confidence: 99%

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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“…Possible structures that form in this process were simulated with DFT [14]. It is now well established that NH 3 itself can reduce Cu(II) to Cu(I) [17,43]. In particular, the theoretical phase diagrams shown in Figure 7 indicate that [Cu(OH)] + is readily reduced at low temperatures irrespective of the O 2 pressure.…”

Section: Interactions With Nhmentioning

confidence: 99%

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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Interaction of NH₃with Cu-SSZ-13 Catalyst: A Complementary FTIR, XANES, and XES Study

Cited by 257 publications

References 70 publications

<i>Operando</i> XAFS studies of supported copper oxides for catalytic ammonia combustion

<i>Operando</i> XAFS studies of supported copper oxides for catalytic ammonia combustion

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

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

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