Detailed Chemical Kinetic Study of Acetaldehyde Oxidation and Its Interaction with NO_x

Abstract

This work entails a detailed modeling and experimental study for the oxidation kinetics of acetaldehyde (CH3CHO) and its interaction with NO x . The ignition behavior of CH3CHO/O2/Ar has been investigated in a shock tube over the temperature range of 1149 to 1542 K, with equivalence ratios of 0.5 and 1.0 and pressures near 1.2 bar. Absorbance–time profiles of acetaldehyde were recorded using a mid-IR laser during the autoignition measurements. A comprehensive kinetic model has been developed to quantitatively predict the oxidation of acetaldehyde and its interaction with NO x . The kinetic model has been validated using experimental data of this work and available literature data from shock tube, plug flow, and jet-stirred reactors, freely propagating, and burner-stabilized premixed flames. For better accuracy of the kinetic model, the thermochemistry of 14 important species in the acetaldehyde submechanism was calculated using ab initio methods. The heat of formation of these species was computed using atomization and isodesmic reaction schemes. For the first time, this modeling study examines the effect of NO on acetaldehyde oxidation behavior over a wide range of experimental conditions. In most cases, the proposed kinetic model captures the experimental trends remarkably well. Interestingly, the doping of NO in CH3CHO did not perturb the NTC behavior of CH3CHO in contrast to other fuels, such as n-heptane and dimethyl ether. However, for flow reactor conditions at 1 atm, doping with 504 ppm of NO was found to promote the reactivity of acetaldehyde by lowering the onset temperature for CH3CHO oxidation by ∼140 K. The hydroxyl radical is the main cause of this shift, which originates from the NO + HO2 = OH + NO2 reaction. Further evolution of hydroxyl radicals occurs via the “NO–NO2” looping mechanism and expedites the reactivity of the system. This experimental and modeling work sheds new light on acetaldehyde oxidation behavior and its interaction with NO x under combustion-relevant conditions.

Experimental and Kinetic Modeling Study of 1,3-Dioxolane Oxidation and Comparison with Dimethoxymethane

“…We adopted the 13DO submechanism from the recent work of Wildenberg et al However, such simple adoption did not yield satisfactory results against the experimental data, especially IDTs and speciation data, mainly due to the different base chemistry and new reaction rate of the reaction 13DO (COCOC) = CH 3 CHO + CH 2 O in the kinetic models, which is discussed below. Wildenberg et al adopted AramcoMech 3.0 for the base model, whereas our current model is an extension of our previous work with the base model developed over the past 5 years. ,− We observed that acetaldehyde (CH 3 CHO) is a major intermediate species during 13DO oxidation and is important for the 13DO (see Section ) oxidation. AramcoMech 3.0 does not include the low-temperature chemistry of CH 3 CHO, particularly internal H-abstraction of CH 3 CO 3 and finally leading to ketohydroperoxide, whereas our kinetic model includes these reactions.…”

“…Wildenberg et al adopted AramcoMech 3.0 for the base model, whereas our current model is an extension of our previous work with the base model developed over the past 5 years. ,− We observed that acetaldehyde (CH 3 CHO) is a major intermediate species during 13DO oxidation and is important for the 13DO (see Section ) oxidation. AramcoMech 3.0 does not include the low-temperature chemistry of CH 3 CHO, particularly internal H-abstraction of CH 3 CO 3 and finally leading to ketohydroperoxide, whereas our kinetic model includes these reactions. We updated the rate parameters within the 13DO submechanism wherever deemed necessary to capture the experimental data over a wide range of conditions.…”

“…Oxidation kinetics of 13DO were investigated using the low-pressure shock tube (LPST) at KAUST over T 5 = 1000–1265 K, a P 5 of ∼1 bar, and equivalence ratios (Φ) of 0.5 and 1.0. The details of the experimental procedure can be found elsewhere …”

“…At this wavelength, the interference caused by other intermediates/products is negligible. Our earlier work details the optical setup using the MIRcat-QT laser system. Temperature and pressure dependence of the absorption cross section σ­( T , P ) of 13DO was determined in another experimental campaign .…”

Virtual Special Issue of Recent Advances in Fundamentals of Biomass and Biofuel Combustion

“…Li et al 22 reported their experimental and modelling study of the thermal decomposition of cyclopentanone in a flow reactor. Shrestha et al 23 explored the effect of NOx on the oxidation of acetaldehyde in a shock tube, proposing a comprehensive kinetic model to explain the obtained experimental results. The last paper in the group discussed the oxidation of ammonia.…”