The story of NCN as a key species in prompt-NO formation

Lamoureux, Nathalie; Desgroux, Pascale; Olzmann, Matthias; Friedrichs, Gernot

doi:10.1016/j.pecs.2021.100940

Cited by 17 publications

(9 citation statements)

References 164 publications

(658 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…for the low-temperature oxidation of diethyl ether as a suggested bioderived fuel . Important reactions in the formation of NO x as a main local pollutant (Section ) from carbon-containing fuels involve the cyanonitrene radical, NCN, a species that was postulated from theoretical investigations but was hard to detect quantitatively before highly sensitive techniques such as CRDS (Section ) were available for in situ flame diagnostics . Details of the reaction system CH + N 2 ⇄ NCN + H and the reverse H + NCN reaction that can proceed via four different channels involving doublet and quartet spin states of the nitrogen atom have only very recently been consistently analyzed .…”

Section: Combustion Chemistry Methodologymentioning

confidence: 99%

Combustion, Chemistry, and Carbon Neutrality

Kohse‐Höinghaus

2023

Chem. Rev.

View full text Add to dashboard Cite

Combustion is a reactive oxidation process that releases energy bound in chemical compounds used as fuels�energy that is needed for power generation, transportation, heating, and industrial purposes. Because of greenhouse gas and local pollutant emissions associated with fossil fuels, combustion science and applications are challenged to abandon conventional pathways and to adapt toward the demand of future carbon neutrality. For the design of efficient, low-emission processes, understanding the details of the relevant chemical transformations is essential. Comprehensive knowledge gained from decades of fossil-fuel combustion research includes general principles for establishing and validating reaction mechanisms and process models, relying on both theory and experiments with a suite of analytic monitoring and sensing techniques. Such knowledge can be advantageously applied and extended to configure, analyze, and control new systems using different, nonfossil, potentially zero-carbon fuels. Understanding the impact of combustion and its links with chemistry needs some background. The introduction therefore combines information on exemplary cultural and technological achievements using combustion and on nature and effects of combustion emissions. Subsequently, the methodology of combustion chemistry research is described. A major part is devoted to fuels, followed by a discussion of selected combustion applications, illustrating the chemical information needed for the future.

show abstract

Section: Combustion Chemistry Methodologymentioning

confidence: 99%

Combustion, Chemistry, and Carbon Neutrality

Kohse‐Höinghaus

2023

Chem. Rev.

View full text Add to dashboard Cite

show abstract

“…In the combustion of nitrogen-free fuels, N 2 from the combustion air serves as the nitrogen source and HCN plays a key role as a precursor for nitrogen oxide (NO x ) formation. Here, it is mainly generated in the prompt-NO initiation sequence CH + N 2 → NCN + H → HCN + N …”

Section: Introductionmentioning

confidence: 99%

“…1 In the combustion of nitrogen-free fuels, N 2 from the combustion air serves as the nitrogen source and HCN plays a key role as a precursor for nitrogen oxide (NO x ) formation. Here, it is mainly generated in the prompt-NO initiation sequence CH + N 2 → NCN + H → HCN + N. 2 In light of global attempts to reduce carbon dioxide and NO x emissions, high-temperature nitrogen chemistry continues to be in the focus of reaction kinetics research. Next to the combustion of nitrogen-rich biomass, ammonia (NH 3 ) has gathered considerable attention both as a carbon-free hydrogen carrier as well as a renewable fuel for internal combustion engines.…”

Section: ■ Introductionmentioning

confidence: 99%

Mid-infrared Frequency Modulation Detection of HCN and Its Reaction with O Atoms behind Shock Waves

Stuhr

Friedrichs

2022

J. Phys. Chem. A

Self Cite

View full text Add to dashboard Cite

Hydrogen cyanide (HCN) is the primary cyanide species in combustion processes and plays a key role in the formation of NO x in the combustion of fossil fuels, nitrogencontaining biofuels, and blended hydrocarbon−ammonia mixtures. Robust, sensitive, and time-resolved in situ laser diagnostic methods are needed to gain insight into the combustion chemistry of HCN. Mid-infrared frequency modulation spectroscopy (MIR-FMS) has recently been established as such a quantitative technique for HCN detection behind shock waves. With a minimum detectable fractional absorption of 2 × 10 −4 at a time resolution of 5 μs, an improved spectrometer design enabled the detection of HCN behind shock waves down to the ppm mole fraction level. An Allan noise analysis revealed that a further improvement toward shot-noise limited detection should be possible when fast mid-infrared photodetectors with a higher saturation limit will become available. HCN kinetic profiles in the presence of O( 3 P) atoms from thermal N 2 O decomposition have been measured in the temperature range 1448 K < T < 1954 K. The determined total rate constants for the key HCN oxidation reaction HCN + O, k/(cm 3 mol −1 s −1 ) = 1.88 × 10 14 exp(−64.5 kJ mol −1 /RT)(+28%, −37%), turn out to be largely consistent with previous measurements. These data complete the set of available rate constant studies, by now covering the temperature range 450 K < T < 2500 K and relying on the detection of almost all feasible reactant and product species.

show abstract

“…Hydrogen cyanide (HCN) is formed by gas phase combustion reactions and during devolatilization of fuels containing organic nitrogen, e.g., biomass residues [1,2]. The present work, which is based on the authors' contribution to the virtual 10th European Combustion Meeting 2021 [3], is motivated by the important role of HCN in thermochemical processes and as a key intermediate for modeling nitrogen chemistry in combustion, in particular for prompt-NO formation [1,4]. Prompt-NO formation is initiated by the reaction CH + N 2 → NCN + H [5] and the fate of the NCN radical is largely determined by the branching ratio of its subsequent reaction with H atoms [4]:…”

Section: Introductionmentioning

confidence: 99%

“…Whereas the reverse association/rearrangement channel (a) to CH + N 2 exhibits a slightly negative temperature dependence, the forward channel (b) yields the so-called Fenimore products HCN + N in an activation controlled reaction step [6][7][8]. As a result, the branching becomes highly temperature dependent and switches from the HCN + N channel at high temperatures to the CH + N 2 channel at low temperatures, going along with other non-Fenimore routes for NCN consumption by reactions with H 2 and O atoms [4,9,10]. Although there is general agreement about the importance of this so-called prompt-NO switch and the HCN intermediate for NO x modeling, significant disagreement between experiment and flame modeling studies on the one hand and theoretical rate constant predictions on the other hand remains.…”

Section: Introductionmentioning

confidence: 99%

Quantitative and Sensitive Mid-Infrared Frequency Modulation Detection of HCN behind Shock Waves

Stuhr

Hesse

Friedrichs

2021

Fuels

Self Cite

View full text Add to dashboard Cite

Despite its key role for the study and modeling of nitrogen chemistry and NOx formation in combustion processes, HCN has only rarely been detected under high-temperature conditions. Here, we demonstrate quantitative detection of HCN behind incident and reflected shock waves using a novel sensitive single-tone mid-infrared frequency modulation (mid-IR-FM) detection scheme. The temperature-dependent pressure broadening of the P(26) line in the fundamental CH stretch vibration band was investigated in the temperature range 670K≤T≤1460K, yielding a pressure broadening coefficient for argon of 2γAr296K=(0.093±0.007)cm−1atm−1 and a temperature exponent of nAr=0.67±0.07. The sensitivity of the detection scheme was characterized by means of an Allan analysis, showing that HCN detection on the ppm mixing ratio level is possible at typical shock wave conditions. In order to demonstrate the capability of mid-IR-FM spectroscopy for future high-temperature reaction kinetic studies, we also report the first successful measurement of a reactive HCN decay profile induced by its reaction with oxygen atoms.

show abstract

The story of NCN as a key species in prompt-NO formation

Cited by 17 publications

References 164 publications

Combustion, Chemistry, and Carbon Neutrality

Combustion, Chemistry, and Carbon Neutrality

Mid-infrared Frequency Modulation Detection of HCN and Its Reaction with O Atoms behind Shock Waves

Quantitative and Sensitive Mid-Infrared Frequency Modulation Detection of HCN behind Shock Waves

Contact Info

Product

Resources

About