Journal ArticleDOI
Unveiling Secondary-Ion-Promoted Catalytic Properties of Cu-SSZ-13 Zeolites for Selective Catalytic Reduction of NO<i><sub>x</sub></i>
TLDR
In this paper , a series of Cu-Sm-SSZ-13 zeolites have been prepared by ion-exchanging Sm ions followed by Cu ions, which exhibit superior NH3-SCR performance.Abstract:
The incorporation of secondary metal ions into Cu-exchanged SSZ-13 zeolites could improve their catalytic properties in selective catalytic reduction of NOx with ammonia (NH3-SCR), but their essential roles remain unclear at the molecular level. Herein, a series of Cu-Sm-SSZ-13 zeolites have been prepared by ion-exchanging Sm ions followed by Cu ions, which exhibit superior NH3-SCR performance. The NO conversion of Cu-Sm-SSZ-13 is nearly 10% higher than that of conventional Cu-SSZ-13 (175–250 °C) after hydrothermal ageing, showing an enhanced low-temperature activity. The Sm ions are found to occupy the six-membered rings (6MRs) of SSZ-13 by X-ray diffraction Rietveld refinement and aberration-corrected scanning transmission electron microscopy. The Sm ions at 6MRs can facilitate the formation of more active [ZCu2+(OH)]+ ions at 8MRs, as revealed by temperature-programmed reduction of hydrogen. X-ray photoelectron spectroscopy and density functional theory (DFT) calculations indicate that there exists electron transfer from Sm3+ to [ZCu2+(OH)]+ ions, which promotes the activity of [ZCu2+(OH)]+ ions by decreasing the activation energy of the formation of intermediates (NH4NO2 and H2NNO). Meanwhile, the electrostatic interaction between Sm3+ and [ZCu2+(OH)]+ results in a high-reaction energy barrier for transforming [ZCu2+(OH)]+ ions into inactive CuOx species, thus enhancing the stability of [ZCu2+(OH)]+ ions. The influence of the ion-exchanging sequence of Sm and Cu ions into SSZ-13 is further investigated by combining both experiments and theoretical calculations. This work provides a mechanistic insight of secondary ions in regulating the distribution, activity, and stability of Cu active sites, which is helpful for the design of high-performance Cu-SSZ-13 catalysts for the NH3-SCR reaction. read more
Citations
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Journal ArticleDOI
Highlights on Key Roles of Y on the Hydrothermal Stability at 900 °C of Cu/SSZ-39 for NH3-SCR
TL;DR: In this article , the yttrium ions (Y3+) were employed to improve the hydrothermal stability of the Cu/SSZ-39 catalyst at 900 °C.
Journal ArticleDOI
Recent progress in performance optimization of Cu-SSZ-13 catalyst for selective catalytic reduction of NO x
Pan Li,Ying Xin,Han-Lin Zhang,Fuzhen Yang,Ahui Tang,Do Hyung Han,Junxiu Jia,Jin Rong Wang,Zhen-Gang Li,Zhaoliang Zhang +9 more
TL;DR: In this paper , the recent progress in NH3-SCR performance optimization of Cu-SSZ-13 catalysts is summarized following three aspects: modifying the Cu active sites; introducing the heteroatoms or metal oxides; regulating the morphology.
Journal ArticleDOI
Review of the application of Cu-containing SSZ-13 in NH3-SCR-DeNOx and NH3-SCO
TL;DR: In this article , the state-of-the-art Cu-containing SSZ-13 is presented for the selective catalytic reduction of NOx with ammonia (NH3-SCR-DeNOx).
Journal ArticleDOI
Mechanistic insights into the effects of alkali metal ion on ZSM-11 zeolite synthesis and its catalytic alkylation performance
Xiang Zhi Kong,Jinyang Zhao,K.T. Huo,Ling-Ling Shi,Zhenhua Yan,Jianan Yang,Maocong Hu,Xia Li,Xuguang Liu +8 more
TL;DR: In this article , the effects of alkali metal ion on ZSM-11 zeolite synthesis and properties were investigated using DFT calculations and MD simulations to investigate the precursor reactions between silicates and aluminates as well as the polycondensation of two silicon-aluminum tetrahedral structural units.
References
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Journal ArticleDOI
Selective Catalytic Reduction of NOx with NH3 by Using Novel Catalysts: State of the Art and Future Prospects.
Lupeng Han,Sixiang Cai,Sixiang Cai,Min Gao,Jun-ya Hasegawa,Penglu Wang,Jianping Zhang,Liyi Shi,Dengsong Zhang +8 more
TL;DR: This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts.
Journal ArticleDOI
The State of the Art in Selective Catalytic Reduction of NOx by Ammonia Using Metal‐Exchanged Zeolite Catalysts
TL;DR: An overview of the selective catalytic reduction of NOx by ammonia (NH3•SCR) over metal-exchanged zeolites is given in this paper, where a comparison of Fe•ZSM•5 catalysts prepared by different methods and research groups shows that the preparation method is not a decisive factor in determining catalytic activity.
Journal ArticleDOI
Excellent activity and selectivity of Cu-SSZ-13 in the selective catalytic reduction of NOx with NH3
TL;DR: In this paper, the performance of a Cu ion-exchanged SSZ-13 zeolite in the selective catalytic reduction (SCR) of NO x with NH 3 was observed, in comparison with Cu-beta and ZSM-5 zeolites.
Journal ArticleDOI
Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials
Andrew M. Beale,Andrew M. Beale,Feng Gao,Ines Lezcano-Gonzalez,Ines Lezcano-Gonzalez,Charles H. F. Peden,János Szanyi +6 more
TL;DR: This review briefly discusses the structure and preparation of the CHA structure-based zeolite catalysts, and summarizes the key learnings of the rather extensive (but not complete) characterisation work, and provides some mechanistic details emerging from these investigations.
Journal ArticleDOI
Dynamic multinuclear sites formed by mobilized copper ions in NO x selective catalytic reduction.
Christopher Paolucci,Ishant Khurana,Atish A. Parekh,Sichi Li,Arthur J. Shih,Hui Li,John R. Di Iorio,Jonatan D. Albarracin-Caballero,Aleksey Yezerets,Jeffrey T. Miller,W. Nicholas Delgass,Fabio H. Ribeiro,William F. Schneider,Rajamani Gounder +13 more
TL;DR: It is demonstrated that under reaction conditions, mobilized Cu ions can travel through zeolite windows and form transient ion pairs that participate in an oxygen (O2)–mediated CuI→CuII redox step integral to SCR.