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

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.

scholarly journals Reduction of NOx Emission of a Diesel Engine with a Multiple Injection Pump by SCR Catalytic Converter

2016 ◽  
Vol 64 (4) ◽  
pp. 1205-1210 ◽  
Author(s):  
Vít Marek ◽  
Lukáš Tunka ◽  
Adam Polcar ◽  
Dušan Slimařík
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Catalytic Converter ◽  
Nox Emission ◽  
Multiple Injection ◽  
Scr Catalyst ◽  
Exhaust Gases ◽  
Injection Pump ◽  
Reduction Of Nox

This paper deals with reduction of NOx-emission of a diesel engine with multiple injection pump by SCR catalytic converter. Main aim of the measurement was the detection of SCR catalyst converter efficiency. Tests were realized at the Research and Development workplace of Zetor Tractor a.s. Used engine was equipped with a multiple injection pump with electromagnetic regulator of a fuel charge. During the experiment selective catalytic reduction and diesel particulate filter were used as an after treatment of harmful pollutants reduction. Testing cycle of the eight-point test was chosen and Non-Road Steady Cycle (NRSC) was maintained according to 97/68/EC directive. Results confirmed the dependencies between temperatures of SCR catalyst and exhaust gases and the volume of exhaust gases on efficiency of SCR catalyst. During the operation load of the engine, selective catalytic reduction reached efficiency over 90 %. Used after treatment system is suitable for reduction of harmful pollutants according to the Tier 4f norm.

scholarly journals In Situ DRIFTS Studies of NH3-SCR Mechanism over V2O5-CeO2/TiO2-ZrO2 Catalysts for Selective Catalytic Reduction of NOx

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1307 ◽  
Author(s):  
Yaping Zhang ◽  
Xiupeng Yue ◽  
Tianjiao Huang ◽  
Kai Shen ◽  
Bin Lu
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Oxygen Storage ◽  
In Situ Drifts ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
Reduction Of Nox ◽  
Zro2 Catalyst

TiO2-ZrO2 (Ti-Zr) carrier was prepared by a co-precipitation method and 1 wt. % V2O5 and 0.2 CeO2 (the Mole ratio of Ce to Ti-Zr) was impregnated to obtain the V2O5-CeO2/TiO2-ZrO2 catalyst for the selective catalytic reduction of NOx by NH3. The transient activity tests and the in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) analyses were employed to explore the NH3-SCR (selective catalytic reduction) mechanism systematically, and by designing various conditions of single or mixing feeding gas and pre-treatment ways, a possible pathway of NOx reduction was proposed. It was found that NH3 exhibited a competitive advantage over NO in its adsorption on the catalyst surface, and could form an active intermediate substance of -NH2. More acid sites and intermediate reaction species (-NH2), at lower temperatures, significantly promoted the SCR activity of the V2O5-0.2CeO2/TiO2-ZrO2 catalyst. The presence of O2 could promote the conversion of NO to NO2, while NO2 was easier to reduce. The co-existence of NH3 and O2 resulted in the NH3 adsorption strength being lower, as compared to tests without O2, since O2 could occupy a part of the active site. Due to CeO2’s excellent oxygen storage-release capacity, NH3 adsorption was weakened, in comparison to the 1 wt. % V2O5-0.2CeO2/TiO2-ZrO2 catalyst. If NOx were to be pre-adsorbed in the catalyst, the formation of nitrate and nitro species would be difficult to desorb, which would greatly hinder the SCR reaction. All the findings concluded that NH3-SCR worked mainly through the Eley-Rideal (E-R) mechanism.

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

2017 ◽  
Vol 2 (2) ◽  
pp. 168-179 ◽  
Author(s):  
Jonatan D. Albarracin-Caballero ◽  
Ishant Khurana ◽  
John R. Di Iorio ◽  
Arthur J. Shih ◽  
Joel E. Schmidt ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Hydrothermal Aging ◽  
Small Pore ◽  
Reduction Of Nox

Cu in aged zeolites changes structure during SCR.

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

2019 ◽  
Vol 4 (6) ◽  
pp. 975-985 ◽  
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.

The deactivation mechanism of Pb on the Ce/TiO2 catalyst for the selective catalytic reduction of NOx with NH3: TPD and DRIFT studies

2017 ◽  
Vol 19 (7) ◽  
pp. 5333-5342 ◽  
Author(s):  
Shu-xian Wang ◽  
Rui-tang Guo ◽  
Wei-guo Pan ◽  
Ming-yuan Li ◽  
Peng Sun ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Scr Catalyst ◽  
Tio2 Catalyst ◽  
Poisoning Effect ◽  
Reduction Of Nox ◽  
Deactivation Mechanism

It was well recognized that Pb had a poisoning effect on a SCR catalyst. In this study, the deactivation mechanism of Pb on the Ce/TiO2 catalyst was investigated based on the characterization results of TPD and in situ DRIFT studies.

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

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.

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

Catalysts ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 140 ◽  
Author(s):  
◽  
Keyword(s):  
Selective Catalytic Reduction ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Short Review ◽  
Catalytic Performance ◽  
Catalyst Design ◽  
Catalyst Stability ◽  
Hydrothermal Aging ◽  
Scr Catalysts ◽  
Fast Scr

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.

Application of ReOx/TiO2 Catalysts with an excellent SO2 tolerance in selective catalytic reduction of NOx by NH3

2021 ◽  
Author(s):  
Yanke Yu ◽  
Xianfang Yi ◽  
Jiali Zhang ◽  
Zhaojian Tong ◽  
Changwei Chen ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Reduction Of No ◽  
Nh3 Scr ◽  
So2 Adsorption ◽  
Vanadium Based Catalysts ◽  
Reduction Of Nox ◽  
So2 Tolerance

Non-vanadium-based catalysts with high SO2 tolerance are still challenging to date in selective catalytic reduction of NO by NH3 (NH3-SCR) and SO2 adsorption is the foremost step for the deactivation...

scholarly journals DRIFTS study of a Ce–W mixed oxide catalyst for the selective catalytic reduction of NOx with NH3

2015 ◽  
Vol 5 (4) ◽  
pp. 2290-2299 ◽  
Author(s):  
Kuo Liu ◽  
Fudong Liu ◽  
Lijuan Xie ◽  
Wenpo Shan ◽  
Hong He
Keyword(s):  
Selective Catalytic Reduction ◽  
Mixed Oxide ◽  
Oxide Catalyst ◽  
Catalytic Reduction ◽  
Reaction Pathways ◽  
Mixed Oxide Catalyst ◽  
Fast Scr ◽  
Reduction Of Nox

The mechanism of standard and fast SCR on CeWOx was studied comprehensively, and the possible reaction pathways were proposed.

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