Inhibition Effect of Phosphorus Poisoning on the Dynamics and Redox of Cu Active Sites in a Cu-SSZ-13 NH3-SCR Catalyst for NOx Reduction

2021 ◽  
Vol 55 (18) ◽  
pp. 12619-12629
Author(s):  
Anqi Guo ◽  
Kunpeng Xie ◽  
Huarong Lei ◽  
Valentina Rizzotto ◽  
Limin Chen ◽  
...  
Keyword(s):  
Active Sites ◽  
Nox Reduction ◽  
Scr Catalyst ◽  
Inhibition Effect ◽  
Nh3 Scr ◽  
Phosphorus Poisoning

scholarly journals Deactivation of a Vanadium-Based SCR Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 552
Author(s):  
Johanna Englund ◽  
Sandra Dahlin ◽  
Andreas Schaefer ◽  
Kunpeng Xie ◽  
Lennart Andersson ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Heavy Duty ◽  
Scr Catalyst ◽  
Before And After ◽  
Emission Control System ◽  
Catalyst Poisons

We have investigated how the exhaust gases from a heavy-duty Euro VI engine, powered with biogas impact a vanadium-based selective catalytic reduction (SCR) catalyst in terms of performance. A full Euro VI emission control system was used and the accumulation of catalyst poisons from the combustion was investigated for the up-stream particulate filter as well as the SCR catalyst. The NOx reduction performance in terms of standard, fast and NO2-rich SCR was evaluated before and after exposure to exhaust from a biogas-powered engine for 900 h. The SCR catalyst retains a significant part of its activity towards NOx reduction after exposure to biogas exhaust, likely due to capture of catalyst poisons on the up-stream components where the deactivation of the oxidation catalyst is especially profound. At lower temperatures some deactivation of the first part of the SCR catalyst was observed which could be explained by a considerably higher surface V4+/V5+ ratio for this sample compared to the other samples. The higher value indicates that the reoxidation of V4+ to V5+ is partially hindered, blocking the redox cycle for parts of the active sites.

Modeling of SCR NH3 Storage in the Presence of H2O

2011 ◽  
Author(s):  
Michael A. Smith ◽  
Christopher D. Depcik ◽  
John W. Hoard ◽  
Stanislav V. Bohac ◽  
Dionissios N. Assanis
Keyword(s):  
Diesel Engines ◽  
Active Sites ◽  
Storage Capacity ◽  
Storage Temperature ◽  
Nox Reduction ◽  
Co2 Concentration ◽  
Temperature Programmed Desorption ◽  
Scr Catalyst ◽  
Temperature Programmed ◽  
Aftertreatment Systems

Diesel engines offer excellent fuel economy, but this comes at the expense of higher emissions of nitrogen oxides (NOx) and Particulate Matter (PM). To meet current emissions standards, diesel engines require aftertreatment devices. Concepts using combinations of catalysts are becoming more common in aftertreatment systems to reduce the cost and size of these aftertreatment systems. One combination is an LNT-SCR system where the LNT releases NH3 during a regeneration to be used by the SCR catalyst for further NOx reduction. This involves rich-lean cycling of the exhaust stream, which alters species concentrations in the exhaust. Most notably H2O and CO2 levels can vary from 4%–14% during lean-rich cycling. An investigation was performed using multiple Temperature Programmed Desorption (TPD) experiments to determine how H2O and CO2 affect NH3 storage capacity of an Fe-based zeolite SCR catalyst. It was determined that H2O and CO2 inhibit NH3 storage capacity of the SCR catalyst. This inhibition has shown a linear dependence on H2O and CO2 concentration at constant temperature. It was also determined that H2O is a much stronger inhibitor of NH3 storage capacity then CO2. Additional Temperature Programmed Desorption (TPD) experiments, were run where H2O and CO2 concentration (0%, 6%, and 10%) and the initial storage temperature (200°C, 250°C, 300°C, 350°C) were varied. Results suggest the addition of a reaction that creates competition for active sites on the catalyst between H2O and NH3. The additional reaction allows H2O and NH3 to be stored on open catalytic sites and has improved model accuracy by accounting for large changes in H2O, CO2, and temperature.

NO2 Reaction Pathways With NH3 on an Fe-Zeolite SCR Catalyst

2011 ◽  
Author(s):  
Michael A. Smith ◽  
Christopher D. Depcik ◽  
Stefan Klinkert ◽  
John W. Hoard ◽  
Stanislav V. Bohac ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Catalyst System ◽  
Lean Nox Trap ◽  
Scr Catalyst ◽  
Nh3 Scr ◽  
Nox Conversion ◽  
Lean Nox ◽  
System Part

One approach for nitrogen oxides (NOx) emission control of medium duty diesel engines is through the use of a combination Lean NOx Trap and Selective Catalytic Reduction (LNT-SCR) catalyst system. In this system, part of the NOx conversion occurs via an NH3 SCR catalyst that is dependent on the NO2 to NOx ratio of the feed gas with NO2 being a more advantageous oxidizer. One benefit of using this system is the conversion of NO to NO2 over the LNT which increases the NO2:NOx ratio of the feed gas to the SCR catalyst. An experimental study has been performed to investigate the NO2-NH3 reaction for an Fe-based zeolite SCR catalyst using a bench top flow reactor. The increase in NO2 concentration at the inlet of the SCR results in the formation of large quantities of N2O from 200°C to 400°C. Further experiments determined that N2O and NH3 react above 350°C. This has led to a hypothesis that one primary SCR reaction (Slow SCR) can be replaced with two reaction steps featuring NH3, NO2, and N2O. As a result, this paper proposes five NOx reduction reactions as part of a global mechanism, which would account for the observed experimental behavior.

scholarly journals AFX Zeolite for Use as a Support of NH3-SCR Catalyst Mining through AICE Joint Research Project of Industries–Academia–Academia

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 163
Author(s):  
Masaru Ogura ◽  
Yumiko Shimada ◽  
Takeshi Ohnishi ◽  
Naoto Nakazawa ◽  
Yoshihiro Kubota ◽  
...  
Keyword(s):  
High Performance ◽  
Ionic Species ◽  
Research Project ◽  
Joint Research ◽  
Structure Directing Agent ◽  
Scr Catalyst ◽  
Organic Structure ◽  
Nh3 Scr ◽  
Joint Research Project ◽  
The One

This paper introduces a joint industries–academia–academia research project started by researchers in several automobile companies and universities working on a single theme. Our first target was to find a zeolite for NH3-SCR, that is, zeolite mining. Zeolite AFX, having the same topology of SSZ-16, was found to be the one of the zeolites. SSZ-16 can be synthesized by using an organic structure-directing agent such as 1,1′-tetramethylenebis(1-azonia-4-azabicyclo[2.2.2]octane; Dab-4, resulting in the formation of Al-rich SSZ-16 with Si/Al below five. We found that AFX crystallized by use of N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium ion, called TEBOP in this study, had the same analog as SSZ-16 having Si/Al around six and a smaller particle size than SSZ-16. The AFX demonstrated a high performance for NH3-SCR as the zeolitic support to load a large number of divalent Cu ionic species with high hydrothermal stability.

scholarly journals Prepare a catalyst consist of rare earth minerals to denitrate via NH3-SCR

2020 ◽  
Vol 9 (1) ◽  
pp. 191-202
Author(s):  
Jian Wang ◽  
Chao Zhu ◽  
Baowei Li ◽  
Zhijun Gong ◽  
Zhaolei Meng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Active Sites ◽  
Nh3 Scr ◽  
Composite Oxides ◽  
Rare Earth Minerals ◽  
Denitrification Activity ◽  
Denitrification Reactor ◽  
Surface Active ◽  
Rare Earth Tailings ◽  
Treatment Step

AbstractTo research the roles of rare earth minerals in denitrification via the NH3-SCR, a mixture was made by certain ratio of rare earth concentrates and rare earth tailings, then treated by microwave roasting, and acids and bases to form a denitrification catalyst. The mineral phase structure and surface morphology of the catalyst were characterized by XRD, BET, SEM and EDS. The surface properties of the catalyst were tested by TPD and XPS methods, and the denitrification activity of the catalyst was evaluated in a denitrification reactor. The results showed that the denitrification efficiency increased up to 82% with complete processing. XRD, BET, SEM, and EDS spectrum analysis stated that the treated minerals contained cerium oxides and Fe−Ce composite oxides. The surface of the modified minerals became rough and porous, the surface area increased, and the surface-active sites were exposed. The results of NH3-TPD and NO-TPD showed that the catalyst surface could gradually adsorb more NH3 and NO after each step. XPS analysis indicated that there were more Ce3+, Fe2+, and lattice oxygen in rare earth minerals catalyst after each treatment step.

Redistributing Cu species in Cu-SSZ-13 zeolite as NH3-SCR catalyst via a simple ion-exchange

2021 ◽  
Author(s):  
Ben Liu ◽  
Nangui Lv ◽  
Chan Wang ◽  
Hongwei Zhang ◽  
Yuanyuan Yue ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Scr Catalyst ◽  
Nh3 Scr

Phosphate on ceria with controlled active sites distribution for wide temperature NH3-SCR

2021 ◽  
pp. 128148
Author(s):  
Liang Chen ◽  
Yao Shen ◽  
Qiaoli Wang ◽  
Xiaoxiang Wang ◽  
Yaqing Wang ◽  
...  
Keyword(s):  
Active Sites ◽  
Nh3 Scr

Low-temperature Shift DeNOx Activity of Nanoflake V2O5 loaded WO3/TiO2 as NH3-SCR Catalyst

2022 ◽  
pp. 109191
Author(s):  
Jae Gu Heo ◽  
Mahboob Ullah ◽  
Myoung-Pyo Chun ◽  
Yong Sik Chu ◽  
Seong Gwan Seo ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Shift ◽  
Scr Catalyst ◽  
Nh3 Scr
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