Selective Catalytic Reduction of NOx with NH3 over Cu/SSZ-13: Elucidating Dynamics of Cu Active Sites with In Situ UV–Vis Spectroscopy and DFT Calculations DOI
Yani Zhang, Jun Zhang, Houlin Wang

et al.

The Journal of Physical Chemistry C, Journal Year: 2022, Volume and Issue: 126(20), P. 8720 - 8733

Published: May 12, 2022

Cu/SSZ-13 is the current state-of-the-art catalyst for selective catalytic reduction of NOx with NH3 (NH3-SCR) in diesel after-treatment systems. Recent investigations under situ or operando conditions yielded rich molecular level understanding about dynamic transformations Cu sites during reactions. However, aiming at distinction two SCR-active species this catalyst, that is, Z2CuII and ZCuIIOH, are still scarce. Herein, we apply UV–vis spectroscopic studies combined theoretical calculations to investigate SCR-relevant low temperatures. We demonstrate presence O2, isolated ZCuIIOH readily transform into a double O-bridged dicopper Cu–Cu distance 3.37 Å, whereas cannot undergo such transformation. In addition, displays stronger activity than both by NO oxidation bidentate nitrates. Despite these differences, exhibit similar features NH3-SCR conditions. These findings spectroscopy powerful tool be used provide information on mechanism rational design catalysts.

Language: Английский

In Situ Spectroscopic Studies on the Redox Cycle of NH3−SCR over Cu−CHA Zeolites DOI
Chong Liu,

Hiroe Kubota,

Takehiro Amada

et al.

ChemCatChem, Journal Year: 2020, Volume and Issue: 12(11), P. 3050 - 3059

Published: Feb. 25, 2020

Abstract The selective catalytic reduction of NO with ammonia (NH 3 −SCR) catalyzed by Cu−CHA zeolites is thoroughly investigated using in situ spectroscopic experiments combined on‐line mass spectroscopy (MS) under steady‐state NH −SCR conditions and transient for Cu(II)/Cu(I) redox cycles. Quantitative analysis the XANES spectra show that ‐coordinated Cu(II) species dominant Cu at low temperatures (100–150 °C). At higher temperatures, [Cu(NH ) 2 ] + complex coexist, possibly because rate Cu(II)→Cu(I) step comparable to Cu(I)→Cu(II) oxidation step. In XANES, IR/MS, UV‐vis/MS on half cycle demonstrate occurs via reaction ‐liganded yield N H O. For cycle, Cu(I) 10 % O 200 °C indicate an increased density CHA zeolite exhibits a rate. UV‐vis reoxidation different mixtures oxidant feed gas key role cycle. It suggested only as oxidant, high promotes SCR activity enhancing oxidative activation during

Language: Английский

Citations

75
Viologen‐Immobilized 2D Polymer Film Enabling Highly Efficient Electrochromic Device for Solar‐Powered Smart Window DOI Creative Commons
Zhiyong Wang, Xiangkun Jia, Panpan Zhang

et al.

Advanced Materials, Journal Year: 2021, Volume and Issue: 34(1)

Published: Oct. 8, 2021

Electrochromic devices (ECDs) have emerged as a unique class of optoelectronic for the development smart windows. However, current ECDs typically suffer from low coloration efficiency (CE) and high energy consumption, which thus hindered their practical applications, especially components in solar-powered EC Here, high-performance with fully crystalline viologen-immobilized 2D polymer (V2DP) thin film color-switching layer is demonstrated. The density vertically oriented pore channels (pore size ≈ 4.5 nm; 5.8 × 1016 m-2 ) synthetic V2DP enables utilization redox-active viologen moieties benefits Li+ ion diffusion/transport. As result, as-fabricated achieve rapid switching speed (coloration, 2.8 s; bleaching, 1.2 s), CE (989 cm2 C-1 ), consumption (21.1 µW cm-2 ). Moreover, it managed to fabricate transmission-tunable, self-sustainable window prototypes by integrating transparent solar cells. This work sheds light on designing electroactive polymers molecular precision optoelectronics paves route toward developing self-powered windows offset electricity buildings.

Language: Английский

Citations

67
Spectroscopic Definition of a Highly Reactive Site in Cu-CHA for Selective Methane Oxidation: Tuning a Mono-μ-Oxo Dicopper(II) Active Site for Reactivity DOI
Hannah M. Rhoda, Dieter Plessers, Alexander J. Heyer

et al.

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(19), P. 7531 - 7540

Published: May 10, 2021

Using UV-vis and resonance Raman spectroscopy, we identify a [Cu2O]2+ active site in O2 N2O activated Cu-CHA that reacts with methane to form methanol at low temperature. The Cu-O-Cu angle (120°) is smaller than for the core on Cu-MFI (140°), its coordination geometry zeolite lattice different. Site-selective kinetics obtained by operando show more reactive Cu-MFI. From DFT calculations, find increased reactivity of direct reflection strong [Cu2OH]2+ bond formed along H atom abstraction reaction coordinate. A systematic evaluation these cores reveals higher O-H strength due relative orientation two planes coordinating bidentate O-Al-O T-sites connect lattice. This work our earlier study ( J. Am. Chem. Soc, 2018, 140, 9236-9243) elucidates how constraints can influence reactivity.

Language: Английский

Citations

64
Dynamic Evolution of Zeolite Framework and Metal-Zeolite Interface DOI

Zhong‐Pan Hu,

Jingfeng Han, Yingxu Wei

et al.

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(9), P. 5060 - 5076

Published: April 14, 2022

Zeolites and metal-zeolites are a class of porous materials that have been widely utilized in industry. So far, several fundamental questions relating to the dynamic evolution zeolite framework metal-zeolite interface remain unanswered. Contrary classical view zeolites as static, rigid, changeless material, atoms foreign metals can dynamically interconvert under pretreatment or reaction conditions, making it difficult identify real active centers mechanisms. With development characterization techniques theoretical calculations, more profound understanding at atomic scale has achieved. This critical Review will feature recent progress metal-zeolites, mainly focusing on T–O–T bonds breaking formation, metal valence state transformation, phase evolution, migration. We compare these proposed mechanisms analyze their suitability distinct experimental conditions. highlight identification sites catalytic mechanism should be cautious consider Finally, we summarize usages limitations different characteristic techniques, propose some future research directions about hope bridge gaps between knowledge achieved characterizations nature guide zeolite-based synthesis, modification, application.

Language: Английский

Citations

53
Mechanisms and site requirements for NO and NH3 oxidation on Cu/SSZ-13 DOI
Yilin Wang, Runze Zhao, Kenneth G. Rappé

et al.

Applied Catalysis B Environment and Energy, Journal Year: 2024, Volume and Issue: 346, P. 123726 - 123726

Published: Jan. 15, 2024

Language: Английский

Citations

11
Exploring the Impact of Active Site Structure on the Conversion of Methane to Methanol in Cu‐Exchanged Zeolites DOI Creative Commons
Florian Göltl, Saurabh Bhandari, Edgard A. Lebrón‐Rodríguez

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(23)

Published: April 4, 2024

Abstract In the past, Cu‐oxo or ‐hydroxy clusters hosted in zeolites have been suggested to enable selective conversion of methane methanol, but impact active site's stoichiometry and structure on methanol production is still poorly understood. Herein, we apply theoretical modeling conjunction with experiments study these two factors partial oxidation Cu‐exchanged zeolite SSZ‐13. Phase diagrams developed from first‐principles suggest that Cu‐hydroxy dimers are stabilized when O 2 N used activate catalyst, respectively. We confirm predictions experimentally determine a stepwise process, can convert twice as much compared Cu‐hydroxyl dimers. Our models rationalize how Cu‐di‐oxo up molecules while Cu‐di‐hydroxyl only one molecule per catalytic cycle. These findings imply Cu clusters, at least oxo group hydroxyl groups needed This simple structure–activity relationship allows intuitively understand potential small oxygenated hydroxylated transition metal methanol.

Language: Английский

Citations

11
Dynamic CuII/CuI speciation in Cu-CHA catalysts by in situ Diffuse Reflectance UV–vis-NIR spectroscopy DOI
Chiara Negri, Matteo Signorile, Natale G. Porcaro

et al.

Applied Catalysis A General, Journal Year: 2019, Volume and Issue: 578, P. 1 - 9

Published: March 25, 2019

Language: Английский

Citations

68
Excellent selective catalytic reduction of NOx by NH3 over Cu/SAPO-34 with hierarchical pore structure DOI
Rui Li, Peiqiang Wang,

Shibo Ma

et al.

Chemical Engineering Journal, Journal Year: 2019, Volume and Issue: 379, P. 122376 - 122376

Published: July 30, 2019

Language: Английский

Citations

65
Spectroscopic Evidence of Efficient Generation of Dicopper Intermediate in Selective Catalytic Reduction of NO over Cu-Ion-Exchanged Zeolites DOI
Akira Oda,

Hitomi Shionoya,

Yuusuke Hotta

et al.

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(20), P. 12333 - 12339

Published: Oct. 8, 2020

The key reactive sites in the selective catalytic reduction (SCR) of NO using ammonia (NH3–SCR) are Cu(II)/Cu(I) ammine complexes encapsulated within zeolite catalysts. reaction intermediate important CuI → CuII reoxidation step has been proposed as dicopper species. However, obtaining definitive spectroscopic probe for under NH3–SCR remains a quite challenging subject. Here we report evidence efficient generation over Cu-ion-exchanged zeolites. state Cu ion condition was analyzed fiber-optic UV–vis–NIR spectroscopy; distinct fingerprint (μ–η2:η2-peroxo)dicopper(II) detected. Our assignment rationalized by density functional theory calculations. intensity fingerprints dimeric copper much higher than expected from previous reports, and it also found that such is observable only conditions. This finding strongly supports previously suggested dynamic contributions to catalysis.

Language: Английский

Citations

62
Catalytic site requirements for N2O decomposition on Cu-, Co-, and Fe-SSZ-13 zeolites DOI Creative Commons
Fan Lin, Tahrizi Andana, Yiqing Wu

et al.

Journal of Catalysis, Journal Year: 2021, Volume and Issue: 401, P. 70 - 80

Published: July 19, 2021

Language: Английский

Citations

55