The differentiated effect of NO and NO2 in promoting methane oxidation

Chan, Yii Leng; Barnes, F. J.; Bromly, John; Konnov, Alexander A.; Zhang, Dongke

doi:10.1016/j.proci.2010.05.029

Cited by 32 publications

(5 citation statements)

References 23 publications

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“…[13] Whether from EGR or EHN, the primary kinetic effect of NO 2 on low-temperature auto-ignition is through radical-radical reactions. [14][15][16][17][18][19][20][21][22][23] [28] They found that the recommended rate constants of Tsang and Herron for H 2 + NO 2 , which were based on Slack and Grillo's measurements, led to NO 2 reduction that was much faster than observed experimentally. [29] As part of a broader study on the H 2 /O 2 /NO x submechanism, Mueller et al reported that the model of Park et al was able to reproduce their flow-tube data adequately, whereas the model from Slack and Grillo was not.…”

Section: Introductionmentioning

confidence: 95%

Rate coefficients for fuel + NO2: Predictive kinetics for HONO and HNO2 formation

Chai

Goldsmith

2017

Proceedings of the Combustion Institute

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High-accuracy electronic structure calculations and transition state theory are used to predict the rate coefficients for the H-abstraction reactions H 2 + NO 2 and CH 4 + NO 2. In each case, three different HNO 2 isomers are formed: cis-HONO, trans-HONO, and HNO 2. These results are used as benchmarks to test different combinations of density functionals and basis sets. The performance of these DFT methods are evaluated both with and without the use of subsequent CCSD(T)-F12a single-point energy corrections. The compound method CCSD(T)-F12a/cc-pVTZ-f12//B2PLYPD3/cc-pVTZ is used to predict the rate coefficients for C 2-C 4 alkanes and alkenes + NO 2 , and the resulting activation energies are generalized into rate rules. These new rules will enable accurate rate coefficients for RH + NO 2 reactions for larger hydrocarbons. In all cases, the dominant product for RH + NO 2 is R + cis-HONO, followed by R + HNO 2. Although trans-HONO is the most stable HNO 2 isomer, the rate constants leading to its formation are roughly an order of magnitude smaller.

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Section: Introductionmentioning

confidence: 95%

Rate coefficients for fuel + NO2: Predictive kinetics for HONO and HNO2 formation

Chai

Goldsmith

2017

Proceedings of the Combustion Institute

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“…Besides water and CO 2 , NO x (mainly NO and NO 2 ) are also present in significant amounts among the exhausted gases used in EGR. They play an important role in changing the reactivity of the fresh inlet fuel and consequently altering the ignition delay times − and product emissions. − A typical small-size component of gasoline surrogates is n -pentane. Many efforts were undertaken to study the oxidation of neat n -pentane − or its role as a dual fuel .…”

Section: Introductionmentioning

confidence: 99%

Effects of Bath Gas and NO_x Addition on n-Pentane Low-Temperature Oxidation in a Jet-Stirred Reactor

et al. 2019

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The oxidation of n-pentane (C5H12) in different bath gases (He, Ar, and CO2) and in Ar with NO2 or NO addition has been studied in a jet-stirred reactor at 107 kPa, temperatures between 500 and 1100 K, with a fixed residence time of 2.0 s, under stoichiometric conditions. Four different quantification diagnostics were used: gas chromatography, a chemiluminescence NOx analyzer, continuous wave cavity ring-down spectroscopy, and Fourier transform infrared spectroscopy. The results showed that the onset temperature of the fuel reactivity was the same (575 K) regardless of the type of bath gases. Although the low-temperature fuel oxidation window was not affected by the type of bath gas, the n-pentane conversion was slightly larger when diluted in Ar through the negative temperature coefficient (NTC) region (625-725 K). Above 800 K, the reactivity according to the diluent was in the order CO2 > Ar > He. In the presence of NO2 or NO, it was found that the consumption rate of n-pentane exhibited a different trend below 700 K. The presence of NO2 did not modify the fuel conversion below 675 K. On the contrary, NO addition increased the onset temperature of the fuel reactivity by 75 K and almost no NTC zone was observed. This clearly indicated that NO addition inhibited n-pentane oxidation below 675 K. Above 700 K, n-pentane conversion was promoted by the presence of both NOx additives. The intermediate species HONO was quantified, and a search for HCN and CH3NO2 species was also attempted. A new detailed kinetic mechanism was developed, which allowed a good prediction of the experimental data. Reaction rate and sensitivity analyses were conducted to illustrate the different kinetic regimes induced by the NOx addition. The inhibition by NO of the n-pentane oxidation below 675 K can be explained by its direct reaction with C5H11O2 radicals disfavoring the classical promoting channels via isomerizations, second O2 addition, and formation of ketohydroperoxides, the well-known branching agents during alkane oxidation. With respect to NO2 addition, the major consumption route is via NO2 + CH3 = NO + CH3O, which is not directly related to the direct fuel consumption. HONO formation mainly derives from NO2 reacting with CHiO (i = 2, 3). The reaction, HONO + M = OH + NO + M, is one of the most sensitive reactions for HONO depletion.

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“…Among them, exhaust gas recirculation (EGR) is one of the main technologies to reduce NO x emissions in diesel engines and gas turbines and has been widely used in many new concept combustion apparatuses. − Meanwhile, NO x is also introduced back into the combustion chamber with the exhaust gas. A number of studies have shown that NO x is not only a pollutant but also can significantly promote − or inhibit − the reactivity of hydrocarbons according to the operating conditions, which will greatly alter the ignition and combustion process in the internal combustion engine cylinders and gas turbines equipped with EGR. As a result, an accurate and detailed description of the interactions of NO x and hydrocarbons is very vital to design and operate the advanced combustion engines.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Kinetic Study of the Promoting Effect of Nitrogen Dioxide on Ethane Autoignition in a Rapid Compression Machine

Deng

Zhao

et al. 2020

Energy Fuels

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Nitrogen oxides (NO x : NO2 and NO) are the main pollutants produced in combustion. Previous studies have focused on the NO x forming mechanism and control strategies but have paid less attention to the interaction between NO x and hydrocarbon fuels; even a small amount of NO x can significantly affect the ignitions of hydrocarbons. The ignition characteristic is of great importance for the optimization design and operation control of engines such as diesel engines, which are affected by the self-ignition characteristics of fuels. In this study, a rapid compression machine was used to measure the ignition delay times of seven fuel-lean C2H6/O2/Ar mixtures with [NO2]/[C2H6] ranging from 0.0 to 50% at T c = 760–970 K and P c = 30 bar. The results exhibit no negative temperature coefficient phenomenon in the ignition of ethane with or without NO2. A great reduction in the ignition delay time and the global activation energy is observed in the presence of NO2, which becomes more noticeable with increasing the NO2 concentration. Subsequently, four literature models involving the C2H6/NO2 chemistry were validated against the new measurements. Moreover, the key elementary reactions and important reaction channels controlling the ignition of C2H6/NO2 mixtures were then identified by the detailed chemical kinetic analysis.

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The differentiated effect of NO and NO2 in promoting methane oxidation

Cited by 32 publications

References 23 publications

Rate coefficients for fuel + NO2: Predictive kinetics for HONO and HNO2 formation

Rate coefficients for fuel + NO2: Predictive kinetics for HONO and HNO2 formation

Effects of Bath Gas and NO_x Addition on n-Pentane Low-Temperature Oxidation in a Jet-Stirred Reactor

Experimental and Kinetic Study of the Promoting Effect of Nitrogen Dioxide on Ethane Autoignition in a Rapid Compression Machine

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The differentiated effect of NO and NO2 in promoting methane oxidation

Cited by 32 publications

References 23 publications

Rate coefficients for fuel + NO2: Predictive kinetics for HONO and HNO2 formation

Rate coefficients for fuel + NO2: Predictive kinetics for HONO and HNO2 formation

Effects of Bath Gas and NOx Addition on n-Pentane Low-Temperature Oxidation in a Jet-Stirred Reactor

Experimental and Kinetic Study of the Promoting Effect of Nitrogen Dioxide on Ethane Autoignition in a Rapid Compression Machine

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Effects of Bath Gas and NO_x Addition on n-Pentane Low-Temperature Oxidation in a Jet-Stirred Reactor