Structural and kinetic changes to small-pore Cu-zeolites after hydrothermal aging treatments and selective catalytic reduction of NOx with ammonia

Cu-exchanged small-pore zeolites have been extensively studied in the past decade as state-of-the-art selective catalytic reduction (SCR) catalysts for diesel engine exhaust NOx abatement for the transportation industry. During this time, Fe-exchanged small-pore zeolites, e.g., Fe/SSZ-13, Fe/SAPO-34, Fe/SSZ-39 and high-silica Fe/LTA, have also been investigated but much less extensively. In comparison to their Cu-exchanged counterparts, such Fe/zeolite catalysts display inferior low-temperature activities, but improved stability and high-temperature SCR selectivities. Such characteristics entitle these catalysts to be considered as key components of highly efficient emission control systems to improve the overall catalyst performance. In this short review, recent studies on Fe-exchanged small-pore zeolite SCR catalysts are summarized, including (1) the synthesis of small-pore Fe/zeolites; (2) nature of the SCR active Fe species in these catalysts as determined by experimental and theoretical approaches, including Fe species transformation during hydrothermal aging; (3) SCR reactions and structure-function correlations; and (4) a few aspects on industrial applications.

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The Cu migration of Cu-SAPO-34 catalyst for ammonia selective catalytic reduction of NOx during high temperature hydrothermal aging treatment

Catalysis Today ◽

10.1016/j.cattod.2018.05.029 ◽

2019 ◽

Vol 327 ◽

pp. 126-133 ◽

Cited By ~ 6

Author(s):

Xianghui Li ◽

Yingnan Zhao ◽

Huawang Zhao ◽

Mengke Liu ◽

Yuhan Ma ◽

...

Keyword(s):

High Temperature ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Aging Treatment ◽

Hydrothermal Aging ◽

Reduction Of Nox ◽

Cu Migration

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Recent advances in the preparation of zeolites for the selective catalytic reduction of NOx in diesel engines

Reaction Chemistry & Engineering ◽

10.1039/c8re00214b ◽

2019 ◽

Vol 4 (6) ◽

pp. 975-985 ◽

Cited By ~ 13

Author(s):

Ling Zhang ◽

Qinming Wu ◽

Xiangju Meng ◽

Ulrich Müller ◽

Mathias Feyen ◽

...

Keyword(s):

Selective Catalytic Reduction ◽

Diesel Engines ◽

Catalytic Reduction ◽

Pore Sizes ◽

Recent Advances ◽

Small Pore ◽

Reduction Of Nox ◽

Scr Of Nox

Metal-exchanged zeolites with small pore sizes have attracted much attention in recent years due to their application in the selective catalytic reduction (SCR) of NOx in diesel engines.

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Promotion of the performance of Cu-SSZ-13 for selective catalytic reduction of NOx by ammonia in the presence of SO2 during high temperature hydrothermal aging

Journal of Catalysis ◽

10.1016/j.jcat.2020.06.041 ◽

2020 ◽

Author(s):

Xin Yong ◽

Cuijuan Zhang ◽

Miao Wei ◽

Pingping Xie ◽

Yongdan Li

Keyword(s):

High Temperature ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Hydrothermal Aging ◽

Reduction Of Nox

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Synthesis of SSZ-13 Zeolite in the Presence of N,N,N-Dimethylethylcyclohexyl Ammonium for Selective Catalytic Reduction of NOx

VNU Journal of Science Natural Sciences and Technology ◽

10.25073/2588-1140/vnunst.4915 ◽

2020 ◽

Vol 36 (1) ◽

Author(s):

Dang Van Long ◽

Le Thanh Son ◽

Pham Dinh Trong

Keyword(s):

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

The United States ◽

Structure Directing Agent ◽

Mobile Sources ◽

Nox Conversion ◽

Scr Catalysts ◽

Small Pore ◽

Reduction Of Nox ◽

Scr Of Nox

Abstract: Since NOx emission requirements from stationary and mobile sources are more strictly regulated in the United States, Europe, and other countries; researchers have conducted many studies to improve the performance of selective catalytic reduction (SCR) catalysts to meet more and more stringent emission standards. Herein, we reported the synthesis of small pore zeolite (Cu)-SSZ-13 using N,N,N-dimethylethylcyclohexylammonium as the structure directing agent. The catalytic activity of the fresh and hydrothermal aged copper exchanged supported on SSZ-13 catalyst was investigated in the SCR of NOx using NH3 as a reductant. Cu-SSZ-13 possessing a high SCR performance (NOx conversion reached approximately 100% at 250oC), and high hydrothermal stability in combination with an easy synthesis route is considered to be a potential catalyst for SCR application. Keywords: Zeolite, SSZ-13, synthesis, SCR, NOx.

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Catalysts for the selective catalytic reduction of NOx with NH3 at low temperature

Catalysis Science & Technology ◽

10.1039/c5cy00737b ◽

2015 ◽

Vol 5 (9) ◽

pp. 4280-4288 ◽

Cited By ~ 110

Author(s):

Wenpo Shan ◽

Hua Song

Keyword(s):

Low Temperature ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Scr Catalysts ◽

Small Pore ◽

Reduction Of Nox

This review presents recent studies on low-temperature NH3-SCR catalysts, particularly Mn-based oxides, V2O5/AC, and Cu-based small pore zeolites.

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Selective catalytic reduction of NOx with NH3: opportunities and challenges of Cu-based small-pore zeolites

National Science Review ◽

10.1093/nsr/nwab010 ◽

2021 ◽

Author(s):

Yulong Shan ◽

Jinpeng Du ◽

Yan Zhang ◽

Wenpo Shan ◽

Xiaoyan Shi ◽

...

Keyword(s):

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Hydrothermal Stability ◽

Catalyst Design ◽

Scr Catalyst ◽

Nh3 Scr ◽

Small Pore ◽

Fast Scr ◽

Reduction Of Nox ◽

Significant Opportunity

Abstract Zeolites, as efficient and stable catalysts, are widely used in the environmental catalysis field. Typically, Cu-SSZ-13 with small-pore structure shows excellent catalytic activity for selective catalytic reduction of NOx with ammonia (NH3-SCR) as well as high hydrothermal stability. This review summarizes major advances in Cu-SSZ-13 applied to the NH3-SCR reaction, including the state of copper species, standard and fast SCR reaction mechanism, hydrothermal deactivation mechanism, poisoning resistance, and synthetic methodology. The review gives a valuable summary of new insights on the matching between SCR catalyst design principles and the characteristics of Cu2+-exchanged zeolitic catalysts, highlighting the significant opportunity presented by zeolite-based catalysts. Principles for designing zeolites with excellent NH3-SCR performance and hydrothermal stability are proposed. On the basis of these principles, more hydrothermally stable Cu-AEI and Cu-LTA zeolites are elaborated as well as other alternative zeolites applied to NH3-SCR. Finally, we call attention to the challenges facing Cu-based small-pore zeolites that still need to be addressed.

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