Reaction Analysis and Modeling of Fast SCR in a Cu-Chabazite SCR Catalyst Considering Generation and Decomposition of Ammonium Nitrate

2021 ◽  
Author(s):  
Keiichiro Seki ◽  
Rikuto Ueyama ◽  
Yoshihisa Tsukamoto ◽  
Kenya Ogawa ◽  
Kohei Oka ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Scr Catalyst ◽  
Fast Scr

The Impact of Ammonium Nitrate Species on Low Temperature NOx Conversion Over Cu/CHA SCR Catalyst

2017 ◽  
Vol 10 (4) ◽  
pp. 1691-1696 ◽  
Author(s):  
Jinyong Luo ◽  
Yadan Tang ◽  
Saurabh Joshi ◽  
Krishna Kamasamudram ◽  
Neal Currier ◽  
...  
Keyword(s):  
Low Temperature ◽  
Ammonium Nitrate ◽  
Scr Catalyst ◽  
Nox Conversion ◽  
The Impact ◽  
Nitrate Species

Impact of Hydrothermal Aging on the Formation and Decomposition of Ammonium Nitrate on a Cu/zeolite SCR Catalyst

2017 ◽  
Vol 10 (4) ◽  
pp. 1646-1652 ◽  
Author(s):  
Nathan Ottinger ◽  
Yuanzhou Xi ◽  
Christopher Keturakis ◽  
Z. Gerald Liu
Keyword(s):  
Ammonium Nitrate ◽  
Hydrothermal Aging ◽  
Scr Catalyst

scholarly journals Effect of the NH4NO3 Addition on the Low-T NH3-SCR Performances of Individual and Combined Fe- and Cu-Zeolite Catalysts

2019 ◽  
Vol 5 (4) ◽  
pp. 290-296 ◽  
Author(s):  
R. Villamaina ◽  
I. Nova ◽  
E. Tronconi ◽  
T. Maunula ◽  
M. Keenan
Keyword(s):  
Low Temperature ◽  
Ammonium Nitrate ◽  
Zeolite Catalysts ◽  
Feed Stream ◽  
Combined System ◽  
Zeolite Sample ◽  
Nh3 Scr ◽  
The Poor ◽  
Fast Scr ◽  
Standard Scr

Abstract We have measured NOx conversions and N2O productions over Fe-BEA and Cu-SAPO catalysts and over their sequential arrangements under Enhanced SCR conditions, resulting from the addition of an aqueous solution of ammonium nitrate (AN) to the typical Standard SCR feed stream, and we have compared them to those observed under Standard and Fast SCR conditions. The expected strong enhancement of the poor low temperature activity of the Fe-BEA catalyst was confirmed: both NH3 and NOx conversions and N2O formations similar to those of the Fast SCR reaction were achieved when cofeeding ammonium nitrate. On the other hand, the Cu-SAPO efficiency was drastically decreased by the addition of AN at low temperatures, possibly due to trapping of the ammonium nitrate salt within the SAPO zeolite, characterized by smaller pores than those of the BEA zeolite. The Cu-SAPO performances were recovered only at T > 250 °C with a huge release of N2O due to the thermal decomposition of AN. The combined system with the Fe-zeolite sample placed upstream of the Cu-zeolite also exhibited outstanding low temperature deNOx performances, with even lower N2O production than over the Fe-zeolite only at the same Enhanced SCR (E-SCR) conditions.

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.

Ammonium Nitrate Formation and Decomposition on an Extruded Vanadium-Based SCR Catalyst

2020 ◽  
Author(s):  
Nathan Ottinger ◽  
Yuanzhou Xi ◽  
Christopher Keturakis ◽  
Z. Gerald Liu
Keyword(s):  
Ammonium Nitrate ◽  
Scr Catalyst

scholarly journals Ammonium-Salt Formation and Catalyst Deactivation in the SCR System for a Marine Diesel Engine

Catalysts ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 21 ◽  
Author(s):  
Yuanqing Zhu ◽  
Qichen Hou ◽  
Majed Shreka ◽  
Lu Yuan ◽  
Song Zhou ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Decomposition Reaction ◽  
Marine Diesel Engine ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Scr Catalyst ◽  
Marine Diesel ◽  
Fast Scr ◽  
Exhaust Gas Temperature ◽  
Scr System

Due to the low temperature and complex composition of the exhaust gas of the marine diesel engine, the working requirements of the selective catalytic reduction (SCR) catalyst cannot be met directly. Moreover, ammonium sulfate, ammonium nitrate, and other ammonium deposits are formed at low temperatures, which block the surface or the pore channels of the SCR catalyst, thereby resulting in its reduction or even its loss of activity. Considering the difficulty of the marine diesel engine bench test and the limitation of the catalyst sample test, a one-dimensional simulation model of the SCR system was built in this paper. In addition, the deactivation reaction process of the ammonium salt in the SCR system and its influencing factors were studied. Based on the gas phase and the surface reaction kinetics, the models of the urea decomposition, the surface denitrification, the nitrate deactivation, and the sulfate deactivation were both constructed and verified in terms of accuracy. Moreover, the formation/decomposition reaction pathway and the catalytic deactivation of ammonium nitrate and ammonium bisulfate, as well as the composition concentration and the exhaust gas temperature range were correspondingly clarified. The results showed that within a certain range, the increase of the NO2/NOx ratio was conducive to the fast SCR reaction and the NH4NO3 formation’s reaction. Increasing the exhaust gas temperature also raised the NO2/NOx ratio, which was beneficial to both the fast SCR reaction and the NH4NO3 decomposition reaction, respectively. Furthermore, the influence of the SO2 concentration on the denitrification efficiency decreased with the increase of the exhaust gas temperature because of increasing SCR reaction rate and reversibility of ammonia sulfate formation, and when the temperature of the exhaust gas was higher than 350 °C, the activity of the catalyst was almost unaffected by ammonia sulfate.

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