Effect of Mass Transfer on the Performance of Selective Catalytic Reduction (SCR) Systems

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Nimrod Kapas ◽  
Tariq Shamim ◽  
Paul Laing
Keyword(s):  
Mass Transfer ◽  
Selective Catalytic Reduction ◽  
Single Channel ◽  
Catalytic Reduction ◽  
Mass Transfer Rate ◽  
Isothermal Model ◽  
One Dimensional ◽  
Scr Catalysts ◽  
Fast Scr ◽  
Conversion Performance

This paper presents a computational investigation of the effect of mass transfer on the performance of selective catalytic reduction (SCR) catalysts, which are employed to reduce NOx emissions from diesel engines. The paper employs a single-channel based, one-dimensional, isothermal model. The heterogeneous surface chemistry is modeled by considering standard and fast SCR mechanisms, and the mass transfer rate is described by using a one-dimensional film model and dimensionless Sherwood (Sh) number. The paper investigates the effect of Sh numbers on the catalyst conversion performance at various temperatures and space velocities. The results show that the effect of the Sh number on the SCR catalyst performance is temperature dependent and is more pronounced at high space velocities. In general, higher Sh numbers lead to increased conversion efficiencies.

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.

A Computational Investigation of Industrial Selective Catalytic Reduction Systems for NOx Control

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Oghare Victor Ogidiama ◽  
Tariq Shamim
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Inlet Temperature ◽  
Complex Processes ◽  
Fast Scr ◽  
Conversion Performance ◽  
Nox Control ◽  
No2 Reduction ◽  
Scr System ◽  
Reaction Processes

The selective catalytic reduction (SCR) is a promising NOx (a mixture of NO and NO2) reduction technology for various applications. The SCR process entails the conversion of NOx by the use of a reducing agent such as ammonia and a suitable catalyst. Due to increasingly stricter NOx emission regulations, the SCR technology for NOx control needs continuous improvement. The improvement requires better understanding of complex processes occurring in the SCR system. The current study employs a mathematical model to elucidate the effect of key operating and geometric parameters on the performance of SCR systems. The model considers both standard and fast SCR reaction processes. The model was used to investigate the effects of NH3/NOx and NO2/NOx ratios in the exhaust on the SCR performance and the effect of using a dual layer SCR system. Furthermore, the effect of different operating parameters and the interdependence of parameters is analyzed by using a factorial approach. The results show that the SCR performance is very sensitive to NH3/NOx ratio. The SCR performance is also affected by the NO2/NOx ratio particularly at low temperatures. The optimal NOx conversion performance requires a combination of NH3/NOx ratio of 1.0, NO2/NOx ratio of 0.5, low space velocities, and high inlet temperature. The results depict that adding a second catalyzed layer results in increased reaction activity especially when the concentration is still high after the first layer.

scholarly journals A review of Mn-containing oxide catalysts for low temperature selective catalytic reduction of NOx with NH3: reaction mechanism and catalyst deactivation

RSC Advances ◽  
2017 ◽  
Vol 7 (42) ◽  
pp. 26226-26242 ◽  
Author(s):  
Shengen Zhang ◽  
Bolin Zhang ◽  
Bo Liu ◽  
Shuailing Sun
Keyword(s):  
Reaction Mechanism ◽  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Catalyst Deactivation ◽  
Catalytic Reduction ◽  
Oxide Catalysts ◽  
Scr Catalysts ◽  
Reduction Of Nox

The reactions over Mn-containing selective catalytic reduction (SCR) catalysts.

Insights into sulfur poisoning and regeneration of Cu-SSZ-13 catalysts: In situ Cu and S K-edge XAS studies

2021 ◽  
Author(s):  
Vitaly Mesilov ◽  
Sandra Dahlin ◽  
Susanna Liljegren Bergman ◽  
Peter Sams Hammershøi ◽  
Shibo Xi ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Catalytic Reduction ◽  
Sulfur Poisoning ◽  
X Ray ◽  
Scr Catalysts ◽  
X Ray Absorption

In situ Cu and S K-edge X-ray absorption spectroscopy (XAS) was used for the investigation of sulfur-poisoned and regenerated Cu-SSZ-13 selective catalytic reduction (SCR) catalysts. Sulfur in the oxidation state...

Iron-exchanged high-silica LTA zeolites as hydrothermally stable NH3-SCR catalysts

2019 ◽  
Vol 4 (6) ◽  
pp. 1050-1058 ◽  
Author(s):  
Taekyung Ryu ◽  
Yonjoo Kang ◽  
In-Sik Nam ◽  
Suk Bong Hong
Keyword(s):  
High Activity ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Hydrothermal Aging ◽  
Reduction Of No ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
High Silica

Iron-exchanged high-silica LTA zeolites exhibit high activity for selective catalytic reduction of NOx by NH3, even after hydrothermal aging at 900 °C.

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