Selective Catalytic Reduction of NOx

Kröcher, Oliver

doi:10.3390/catal8100459

Cited by 25 publications

(13 citation statements)

References 17 publications

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“…However, such systems, including those incorporating SCR, a characterized by efficiency drops as they age. There are several known mechanisms of An analysis of SCR reactor deactivation impact on NO x emissions from a compression ignition engine SCR deactivation and they can be classified as follows [1,3]…”

Section: Legal Requirements Regarding No X Emissionmentioning

confidence: 99%

“…Nowadays, the selective catalytic reduction (SCR) of NO x by NH 3 is recognized as the most comprehensive solution for NO x emission control. The system is capable of reaching high overall conversion efficiency -frequently exceeding 90% [2,3]. It is considered to be the major future deNO x solution and considerable research is being conducted to maximize its potential [4,5].…”

Section: Introductionmentioning

confidence: 99%

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An analysis of SCR reactor deactivation impact on NO<sub>x</sub> emissions from a compression ignition engine

Dzida¹,

Brzeżański²

2019

Combustion Engines

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Catalytic exhaust gas aftertreatment devices fitted to combustion engines are susceptible to partial deactivation as their operating time progresses. This includes selective catalytic reduction (SCR) reactors meant for NOx emission control. There are several known deactivation mechanisms of SCR reactors already analyzed in detail in the literature. This paper, however, approaches the analysis of reactor deactivation by comparison of exhaust gas characteristics over repeatable cycle for fresh and aged samples of a SCR reactor for non-road mobile machinery. The research aims to outline which parameters describing the SCR reactor’s performance are most affected by its ageing. In order to do that, fresh and aged samples of the reactor were tested under the Non Road Steady Cycle. The acquired emission results, including concentration traces of particular compounds were analyzed. The specific NOx emission of the aged reactor was significantly higher than that of the fresh one. The NOx conversion efficiency of both reactors was found similar at periods of steady engine operation. It was recognized that during transient conditions the NOx conversion efficiency of the aged reactor was decreased. It was found that the main factor contributing to that phenomenon is the drop in the ammonia storage capacity of the aged SCR sample.

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Section: Legal Requirements Regarding No X Emissionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An analysis of SCR reactor deactivation impact on NO<sub>x</sub> emissions from a compression ignition engine

Dzida¹,

Brzeżański²

2019

Combustion Engines

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“…Nitrogen oxides (NO and NO 2 ) 1 are the primary pollutants responsible for air pollution, damage the ozone layer, and are capable of direct damage to human health. 2 , 3 Therefore, the effective treatment of NO x is important from both environmental and social standpoints. Currently, the main source of NO x (NO accounts for >90%) in the atmosphere is nitrogen-containing fuels, such as coke powder and coal in power plants, industrial boilers, and smelters.…”

Section: Introductionmentioning

confidence: 99%

Effect of Calcination Temperature on the Activation Performance and Reaction Mechanism of Ce–Mn–Ru/TiO₂ Catalysts for Selective Catalytic Reduction of NO with NH₃

et al. 2020

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In this study, anatase TiO 2 -supported cerium, manganese, and ruthenium mixed oxides (CeO x −MnO x −RuO x / TiO 2 ; CMRT catalysts) were synthesized at different calcination temperatures via conventional impregnation methods and used for selective catalytic reduction (SCR) of NO x with NH 3 . The effect of calcination temperature on the structure, redox properties, activation performance, surface-acidity properties, and catalytic properties of the CMRT catalysts was investigated. The results show that the CMRT catalyst calcined at 350 °C exhibits the most efficient lowtemperature (<120 °C) denitration activity. Moreover, the selective catalytic oxidation (SCO) reaction of ammonia is intensified when the reaction temperature is >200 °C, which leads to a decrease in the N 2 selectivity of the CMRT catalysts and further results in an increase in the production of NO and N 2 O byproducts. X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy show that the CMRT catalyst calcined at 350 °C contains more Ce 4+ , Mn 4+ , Ru 4+ , and lattice oxygen, which greatly improve the catalyst's ability to activate NO that promotes the NH 3 -SCR reaction. The Ru n+ sites of the CMRT catalyst calcined at 250 °C are the competitive adsorption sites of NO and NH 3 molecules, while those of the CMRT catalyst calcined at 350 and 450 °C are active sites. Both the Langmuir−Hinshelwood (L−H) mechanism and the Eley−Rideal (E−R) mechanism occur on the surface of the CMRT catalyst at the low reaction temperature (100 °C).

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“…The traditional SCR catalysts are active within the temperature window of 300-400 • C [3,4]. Even though some of the traditional catalyst compositions such as V 2 O 5 -WO 3 / TiO 2 or Fe-zeolite-based catalysts can lower down their working temperature window to be as low as 250 or even 200 • C [5][6][7][8][9][10], there is still a strong demand in developing SCR catalysts to be active at less than 200 • C and placing them downstream of the electrostatic precipitator and desulfurizer [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

Lee

Bai

2019

Catalysts

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The byproducts of ammonia-selective catalytic reduction (NH3-SCR) process over MnFe/TiO2 catalysts under the conditions of both with and without SO2 poisoning were analyzed. In addition to the NH3-SCR reaction, the NH3 oxidation and the NO oxidation reactions were also evaluated at temperatures of 100–300 °C to clarify the reactions occurred during the SCR process. The results indicated that major byproducts for the NH3 oxidation and NO oxidation tests were N2O and NO2, respectively, and their concentrations increased as the reaction temperature increased. For the NH3-SCR test without the presence of SO2, it revealed that N2O was majorly from the NH3-SCR reaction instead of from NH3 oxidation reaction. The byproducts of N2O and NO2 for the NH3-SCR reaction also increased after increasing the reaction temperature, which caused the decreasing of N2-selectivity and NO consumption. For the NH3-SCR test with SO2 at 150 °C, there were two decay stages during SO2 poisoning. The first decay was due to a certain amount of NH3 preferably reacted with SO2 instead of with NO or O2. Then the catalysts were accumulated with metal sulfates and ammonium salts, which caused the second decay of NO conversion. The effluent N2O increased as poisoning time increased, which was majorly from oxidation of unreacted NH3. On the other hand, for the NH3-SCR test with SO2 at 300 °C, the NO conversion was not decreased after increasing the poisoning time, but the N2O byproduct concentration was high. However, the SO2 led to the formation of metal sulfates, which might inhibit NO oxidation reactions and cause the concentration of N2O gradually decreased as well as the N2-selectivity increased.

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Selective Catalytic Reduction of NOx

Abstract: n/a

Cited by 25 publications

References 17 publications

An analysis of SCR reactor deactivation impact on NO<sub>x</sub> emissions from a compression ignition engine

An analysis of SCR reactor deactivation impact on NO<sub>x</sub> emissions from a compression ignition engine

Effect of Calcination Temperature on the Activation Performance and Reaction Mechanism of Ce–Mn–Ru/TiO₂ Catalysts for Selective Catalytic Reduction of NO with NH₃

Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

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Selective Catalytic Reduction of NOx

Abstract: n/a

Cited by 25 publications

References 17 publications

An analysis of SCR reactor deactivation impact on NO<sub>x</sub> emissions from a compression ignition engine

An analysis of SCR reactor deactivation impact on NO<sub>x</sub> emissions from a compression ignition engine

Effect of Calcination Temperature on the Activation Performance and Reaction Mechanism of Ce–Mn–Ru/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3

Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

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Effect of Calcination Temperature on the Activation Performance and Reaction Mechanism of Ce–Mn–Ru/TiO₂ Catalysts for Selective Catalytic Reduction of NO with NH₃