NOx abatement and N2O formation over urea-SCR systems with zeolite supported Fe and Cu catalysts in a nonroad diesel engine

Shin, Youngjin; Jung, Young-Dae; Cho, Chong Pyo; Pyo, Young Dug; Jang, Jinyoung; Kim, Gangchul; Kim, Tae Min

doi:10.1016/j.cej.2019.122751

Cited by 64 publications

(26 citation statements)

References 39 publications

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“…An issue that is becoming increasingly recognized is the unwanted formation of N 2 O during SCR where small pore Cu- and Fe-zeolites are used as catalysts. − A similar phenomenon has also been observed when Mn-Fe spinels, V 2 O 5 -WO 3 /TiO 2 , and Mn/Ti-Si are used as the catalyzing agent. Although historically exempt from emissions regulations due to their believed lack of toxicity, harmful indications following long-term exposure and a global warming potential almost 300 times that of CO 2 mean that N 2 O will inevitably become the subject of increasingly exacting legislation beyond emissions standards.…”

Section: Introductionmentioning

confidence: 82%

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N₂O Formation during NH₃-SCR

et al. 2021

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Unwanted N2O formation is a problem that has been noted in selective catalytic reduction (SCR) where copper zeolite catalysts are utilized. With its immense global warming potential and long-term stability, elevated atmospheric N2O has already been identified as a future challenge in the war on climate change. This paper explores the phenomenon of N2O formation during NH3-SCR over Cu-SSZ-13 catalysts, which are currently commercialized in automotive emissions control systems, and proposes a link between N2O production and the local copper environment found within the zeolite. To achieve this, a comparison is made between two Cu-SSZ-13 samples with different copper co-ordinations produced via different synthesis methods. A combination of synchrotron X-ray absorption near-edge spectroscopy, UV–vis, Raman, and density functional theory (DFT) is used to characterize the nature of copper species present within each sample. Synchrotron IR microspectroscopy is then used to compare their behavior during SCR under operando conditions and monitor the evolution of nitrate intermediates, which, along with further DFT, informs a mechanistic model for nitrate decomposition pathways. Increased N2O production is seen in the Cu-SSZ-13 sample postulated to contain a linear Cu species, providing an important correlation between the catalytic behavior of Cu-zeolites and the nature of their metal ion loading and speciation.

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Section: Introductionmentioning

confidence: 82%

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N₂O Formation during NH₃-SCR

et al. 2021

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“…Meanwhile, NH 3 may react with NO 2 alone. This is the slow reaction rate of SCR ( r slw ) because the reaction occurs very slowly, slower than the major SCR reactions 41…”

Section: Methodsmentioning

confidence: 99%

Ammonia injection optimization for selective catalytic reduction aftertreatment systems

Plá

Bares

Sanchis

et al. 2020

International Journal of Engine Research

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This work presents an optimized ammonia injection strategy for the Worldwide Harmonized Light Vehicles Test Cycle and its potential benefits in terms of NO x emissions and ammonia consumption in selective catalytic reduction. An optimization tool based on optimal control was used to improve the ammonia injection in the selective catalytic reduction with different NO x emission limits. This optimal control can be used in two ways: one to minimize NO x emission and another to reduce the ammonia consumption in the selective catalytic reduction. The optimized strategy and the standard ammonia injection strategy were tested and compared on a fully instrumented engine test bench when applied in a Worldwide Harmonized Light Vehicles Test Cycle. The results showed a considerable improvement in the use of the optimization tool. When compared to the standard calibration, the new injection strategy for the same amount of ammonia injection reduced NO x emissions by 13.7%, and for the same NO x concentration emissions 33.5% of ammonia consumption was saved.

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“…NO X emission in internal combustion engines is mainly NO and a small amount of NO 2. 1 Exhaust gas recirculation (EGR) is often introduced to reduce NO X emission in the actual combustion of internal combustion engines. At the same time, due to the dilution and oxidation in the fresh intake air, NO in EGR gas is oxidized to NO 2.…”

Section: Introductionmentioning

confidence: 99%

Effect of NO ₂ on ignition characteristics of methanol and chemical kinetics analysis

Dong

Wang

et al. 2022

Intl J of Energy Research

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Summary Based on the shock tube experiments, the influence of NO2 on the ignition characteristics of methanol fuel was systematically studied. The ignition delay time of the CH3OH/NO2/O2/Ar mixture with equivalence ratios of 0.5, 1, and 1.5 was measured at the reflected shock temperatures of 1100 ~ 1650 K and the reflected shock pressure of 0.20 MPa. The methanol–NO2 mechanism was newly constructed based on previously developed mechanisms for methanol and NO2 reaction pathways. The new combined reduced mechanism could well predict the ignition delay time of the CH3OH/NO2/O2/Ar mixture. Based on the newly constructed methanol–NO2 mechanism, the reaction path, sensitivity, and important elementary reactions of the stoichiometric mixture were analyzed, and the reasons why NO2 promoted the ignition of methanol fuel were found out: the increase of OH radicals generation and rapid accumulation in the early ignition stage enhanced the activity of the reaction system, interfered the ignition process of CH3OH/NO2/O2/Ar mixture in advance, and promoted the ignition of methanol fuel.

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NOx abatement and N2O formation over urea-SCR systems with zeolite supported Fe and Cu catalysts in a nonroad diesel engine

Cited by 64 publications

References 39 publications

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N₂O Formation during NH₃-SCR

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N₂O Formation during NH₃-SCR

Ammonia injection optimization for selective catalytic reduction aftertreatment systems

Effect of NO ₂ on ignition characteristics of methanol and chemical kinetics analysis

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NOx abatement and N2O formation over urea-SCR systems with zeolite supported Fe and Cu catalysts in a nonroad diesel engine

Cited by 64 publications

References 39 publications

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N2O Formation during NH3-SCR

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N2O Formation during NH3-SCR

Ammonia injection optimization for selective catalytic reduction aftertreatment systems

Effect of NO 2 on ignition characteristics of methanol and chemical kinetics analysis

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Product

Resources

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Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N₂O Formation during NH₃-SCR

Elucidating the Significance of Copper and Nitrate Speciation in Cu-SSZ-13 for N₂O Formation during NH₃-SCR

Effect of NO ₂ on ignition characteristics of methanol and chemical kinetics analysis