Analysis of the Coupling of HC–SCR by Ethanol and NH3–SCR on Real Engine Emissions

Frobert, Arnaud; Raux, S.; Rousseau, Séverine; Blanchard, G.

doi:10.1007/s11244-013-9940-5

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…Since under standard SCR conditions no gas phase reactions leading to hydrogen cyanide could be observed during empty reactor tests (Figure S3), the HCN production obviously is a consequence of HCHO reactions on the SCR catalyst. In contrast to previous studies in literature, which reported the formation of HCN by the reduction of NO with CO or other hydrocarbons, our results demonstrate a similar selectivity trend towards HCN formation but in this case due to the reaction between HCHO and NH 3 (Figure A vs. Figure B).…”

Section: Figurementioning

confidence: 99%

Emission of Toxic HCN During NO_x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

et al. 2020

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Reducing greenhouse gas and pollutant emissions is one of the most stringent priorities of our society to minimize their dramatic effects on health and environment. Natural gas (NG) engines, in particular at lean conditions, emit less CO2 in comparison to combustion engines operated with liquid fuels but NG engines still require emission control devices for NOx removal. Using state‐of‐the‐art technologies for selective catalytic reduction (SCR) of NOx with NH3, we evaluated the interplay of the reducing agent NH3 and formaldehyde, which is always present in the exhaust of NG engines. Our results show that a significant amount of highly toxic hydrogen cyanide (HCN) is formed. All catalysts tested partially convert formaldehyde to HCOOH and CO. Additionally, they form secondary emissions of HCN due to catalytic reactions of formaldehyde and its oxidation intermediates with NH3. With the present components of the exhaust gas aftertreatment system the HCN emissions are not efficiently converted to non‐polluting gases. The development of more advanced catalyst formulations with improved oxidation activity is mandatory to solve this novel critical issue.

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Section: Figurementioning

confidence: 99%

Emission of Toxic HCN During NO_x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

et al. 2020

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“…However, the HC/NO x ratio plays an important role in the NO x -SCR. Frobert et al proposed that the HC/NO x ratio between 4 and 8 gave the maximum de NO x efficiency of 70% at the operating temperature of 408 °C. The figure shows that the HC/NO x ratio is less than 1.5 for all engine loads and fuel blends, which is far below the proper value.…”

Section: Resultsmentioning

confidence: 99%

“…Blends of ethanol into diesel fuel showed the improvement of brake thermal efficiency (BTE). − Several alcohols (e.g., ethanol, 2-propanol, and 1-butanol) as a reducing agent gave a higher NO x conversion compared to hydrocarbons (e.g., toluene and n -octane) due to their higher adsorption strength with Ag/Al 2 O 3 . , By using diffuse reflectance infrared Fourier transform spectroscopy and fast transient techniques, Chansai et al proposed that methanol acted as an in situ source for hydrogen formation and significantly promoted the n -octane-SCR on Ag/Al 2 O 3 . Ethanol showed high potential for NO x -SCR over Ag/Al 2 O 3 ,− compared to ethane, ethylene, and acetic acid . Although ethanol–diesel blend can both enhance BTE and reduce emissions of unburned HC, CO, and PM, ethanol caused an increase in brake specific fuel consumption (BSFC) and NO x . ,− …”

Section: Introductionmentioning

confidence: 99%

Effects of Diesel–Biodiesel–Ethanol Fuel Blend on a Passive Mode of Selective Catalytic Reduction to Reduce NO_x Emission from Real Diesel Engine Exhaust Gas

et al. 2021

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The effects of ethanol on combustion and emission were investigated on a single-cylinder unmodified diesel engine. The ethanol content of 10–50 vol % was chosen to blend with diesel and biodiesel fuels. Selective catalytic reduction (SCR) of nitrogen oxides (NO x ) in the passive mode was also studied under real engine conditions. Silver/alumina (Ag/Al2O3) was selected as the active catalyst, and H2 (3000–10000 ppm) was added to assist the ethanol-SCR. The low cetane number of ethanol resulted in longer ignition delay. The diesel–biodiesel–ethanol fuel blends caused an increase in fuel consumption due to their low calorific value. The brake thermal efficiency of the engine fuelled with relatively low ethanol fraction blends was higher than that of diesel fuel. Unburned hydrocarbons (HC) and carbon monoxide (CO) increased, while NO x decreased with ethanol quantity. The higher ethanol quantity led to increases in the HC/NO x ratio which directly affected the performance of NO x -SCR. Addition of H2 considerably improved the activity of Ag/Al2O3 for NO x reduction. The proper amount of H2 added to promote the ethanol-SCR depended strongly on the temperature of the exhaust where a high fraction of H2 was required at a low exhaust temperature. The maximum NO x conversion of 74% was obtained at a low engine load (25% of maximum load), an ethanol content of 50 vol %, and H2 addition of 10000 ppm.

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“…Da unter Standard‐SCR Bedingungen bei Leerrohrtests keine Gasphasenreaktionen beobachtet werden konnten, die zu Cyanwasserstoff führen (Abbildung S3), ist die Bildung von HCN offensichtlich eine Folge von Reaktionen des HCHO auf dem SCR‐Katalysator. Im Gegensatz zu früheren Studien in der Literatur, welche die Bildung von HCN über die Reduktion von NO mit CO oder anderen Kohlenwasserstoffen berichteten, zeigen unsere Ergebnisse zwar einen ähnlichen Selektivitätstrend zur HCN‐Bildung, aber in diesem Fall aufgrund der Reaktion zwischen HCHO und NH 3 (Abbildung A vs. Abbildung B). Der Vergleich der NO‐Oxidation (Abbildung A) in Gegenwart und Abwesenheit von HCHO zeigt, dass die Umsetzung von HCHO mit der Oxidation von NO um aktive Zentren konkurriert und damit zu einer verringerten NO‐Oxidationsaktivität führt.…”

Section: Figureunclassified

Freisetzung von toxischem HCN bei der Stickoxidreduktion mittels NH₃‐SCR in mager betriebenen Erdgasmotoren

et al. 2020

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Die Reduzierung der Emissionen von Treibhausgasen und gesundheitsgefährdenden Schadstoffen ist eines der wichtigsten Ziele unserer Industriegesellschaft. Erdgasmotoren sind insbesondere bei magerem Betrieb attraktiv, da sie weniger CO2 ausstoßen als Verbrennungsmotoren, die mit flüssigen Kraftstoffen betrieben werden. Sie benötigen allerdings ein katalytisches Kontrollsystem, um Stickoxide (NOx) aus dem Abgas zu entfernen. Hier haben wir das Zusammenspiel der aktuellen Technologie zur Stickoxidreduktion, die selektive katalytische Reduktion (SCR) mittels NH3, und Formaldehyd, einer schädlichen Emission in Erdgasmotoren, untersucht. Bei der NOx Entfernung werden beachtliche Mengen an toxischem Cyanwasserstoff (HCN) gebildet. Alle getesteten Katalysatoren wandeln Formaldehyd teilweise in HCOOH und CO um. Zusätzlich werden Sekundäremissionen von HCN über die katalytische Reaktion von Formaldehyd und dessen Oxidationsintermediaten mit NH3 beobachtet. Da die HCN Emissionen mit den derzeitigen Komponenten nicht effizient in schadstofffreie Gase umgewandelt werden können, ist die Entwicklung von Katalysatoren mit einer gesteigerten Oxidationsaktivität nötig, um dieses kritische Problem zu lösen.

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Analysis of the Coupling of HC–SCR by Ethanol and NH3–SCR on Real Engine Emissions

Cited by 10 publications

References 15 publications

Emission of Toxic HCN During NO_x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Emission of Toxic HCN During NO_x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Effects of Diesel–Biodiesel–Ethanol Fuel Blend on a Passive Mode of Selective Catalytic Reduction to Reduce NO_x Emission from Real Diesel Engine Exhaust Gas

Freisetzung von toxischem HCN bei der Stickoxidreduktion mittels NH₃‐SCR in mager betriebenen Erdgasmotoren

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Analysis of the Coupling of HC–SCR by Ethanol and NH3–SCR on Real Engine Emissions

Cited by 10 publications

References 15 publications

Emission of Toxic HCN During NOx Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Emission of Toxic HCN During NOx Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Effects of Diesel–Biodiesel–Ethanol Fuel Blend on a Passive Mode of Selective Catalytic Reduction to Reduce NOx Emission from Real Diesel Engine Exhaust Gas

Freisetzung von toxischem HCN bei der Stickoxidreduktion mittels NH3‐SCR in mager betriebenen Erdgasmotoren

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Emission of Toxic HCN During NO_x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Emission of Toxic HCN During NO_x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Effects of Diesel–Biodiesel–Ethanol Fuel Blend on a Passive Mode of Selective Catalytic Reduction to Reduce NO_x Emission from Real Diesel Engine Exhaust Gas

Freisetzung von toxischem HCN bei der Stickoxidreduktion mittels NH₃‐SCR in mager betriebenen Erdgasmotoren