Methanol Oxidation and Its Interaction with Nitric Oxide

Abstract

An experimental and theoretical study of the oxidation of methanol in the absence and in the presence of NO has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the temperature range 700−1500 K. The influence of the temperature, oxygen concentration, and presence of NO on the concentrations of methanol, CO, CO2, and NO has been analyzed. A reaction mechanism based on the model of Glarborg et al. for hydrocarbons/NO interactions, updated in relation to the methanol reaction subset has been used for calculations. The results show that the oxidation regime of methanol for different air excess conditions is very similar in the absence of NO, but significant differences are observed when NO is present. The presence of NO implies a different behavior depending on the stoichiometry, in the way that such presence results in a inhibition of methanol conversion for richest conditions, while it promotes methanol oxidation for very lean conditions. The experimental results are analyzed in terms of detailed chemistry and the main issues are discussed.

Experimental and Kinetic Modeling Study of Methanol Ignition and Oxidation at High Pressure

“…Some CO 2 is also produced directly from the formyl radical by the reaction with HO 2 under fuel-rich conditions at 20 bar, and from CO, with HOCO as an intermediate species, under stoichiometric and fuel-lean conditions. The main reaction pathways under the present conditions are consistent with those reported for atmospheric pressure [13][14][15]. Unlike unsaturated fuels such as ethylene [45], the high pressure does not introduce additional oxidation pathways for methanol because addition reactions of OH and O 2 are not important.…”

“…These reactions yield hydroxymethyl and methoxy radicals, with the former radical being predominant. As expected [13][14][15], the hydroxymethyl radical mainly react with oxygen (R18), while methoxy undergoes thermal decomposition (R19). However, due to the larger value of k 27 in the present work, compared to previous modeling studies, the reaction of CH 3 O with O 2 (R27) becomes competitive under lean conditions.…”

“…The mechanism used in the present study is based on the atmospheric pressure methanol schemes by the authors [14,15], drawing also on previous high pressure work on oxidation of CO and CH 4 [18,20,21]. The methanol subset has been updated with results from recent theoretical work [22][23][24] and from ab initio calculations and RRKM analysis made as part of the present work on reactions of CH 2 OH and CH 3 O (dissociation, isomerization, reaction with O 2 ).…”

“…Laboratory experiments allow more controlled conditions compared to tests in engines; methanol oxidation has been studied in flames [6][7][8], stirred reactors [9], static reactors [10,11], flow reactors [12][13][14][15], Rapid Compression Machines [16], and shock tubes [17]. Of these studies, only three have been carried out at elevated pressures, i.e.…”

05/02669 Effects of oxygenate concentration on species mole fractions in premixed n-heptane flames

“…However, the oxidation mechanism of alcohols involves the production of oxygenated and non-oxygenated intermediates directly from the fuel by dehydration or dehydrogenation [31]. The experimental and modeling studies have indicated that methanol and ethanol oxidations are initiated mostly by reactions with the OH and H radicals [32,33]. The addition of methanol and ethanol into fuel blends acts as traps for H and OH, and therefore reduces the n-heptane oxidation.…”