Experimental and kinetic modeling of the reduction of NO by isobutane in a Jsr at 1 atm

Abstract

A kinetic study of the reduction of nitric oxide (NO) by isobutane in simulated conditions of the reburning zone was carried out in a fused silica jet-stirred reactor operating at 1 atm, at temperatures ranging from 1100 to 1450 K. In this new series of experiments, the initial mole fraction of NO was 1000 ppm, that of isobutane was 2200 ppm, and the equivalence ratio was varied from 0.75 to 2. It was demonstrated that for a given temperature, the reduction of NO is favored when the temperature is increased and a maximum NO reduction occurs slightly above stoichiometric conditions. The present results generally follow those reported in previous studies of the reduction of NO by C 1 to C 3 hydrocarbons or natural gas as reburn fuel. A detailed chemical kinetic modeling of the present experiments was performed using an updated and improved kinetic scheme (979 reversible reactions and 130 species). An overall reasonable agreement between the present data and the modeling was obtained. Furthermore, the proposed kinetic mechanism can be successfully used to model the reduction of NO by ethylene, ethane, acetylene, a natural gas blend (methane-ethane 10:1), propene, and HCN. According to this study, the main route to NO reduction by isobutane involves ketenyl radical. The model indicates that the reduction of NO proceeds through the reaction path: iC 4 H 10 : C 3 H 6 : C 2 H 4 : C 2 H 3 : C 2 H 2 : HCCO; HCCO ϩ NO : HCNO ϩ CO and HCN ϩ CO 2 ; HCNOϩH : HCN : NCO : NH; NH ϩ NO : N 2 and NH ϩ H : followed by N ϩ NO : N 2 ; NH ϩ NO : N 2 O followed by N 2 O ϩ H : N 2 .

Absolute Rate Coefficient of the HCCO + NO Reaction over the Range T = 297−802 K

“…Indeed k 5a above is about a factor of 10 less (1200-1700 K) than that used in recent detailed chemical kinetic models of reburning. 12,13,39 The experimental rate constants reported here agree in both magnitude and dependence on temperature with the very recent molecular-orbital/micro-variational RRKM calculations by Lin et al, 54 which were made available to us during the review stage of this work. Their predicted total rate constant for this reaction is k 5 (T) calcd ) 2.27 × 10 -8 T -0.98 exp(-190 K/T) cm 3 s -1 .…”

On the kinetics of hydrocarbons oxidation from natural gas to kerosene and diesel fuel

“…The kinetic scheme used here is based on the comprehensive mechanism developed for the reduction of NO by natural gas blends in simulated reburning conditions using a natural gas blend, 6 methane, ethane, ethylene, acetylene, propane, propene, n-butane and isobutane [7][8][9][10][11][12][13][14][15] and the oxidation of 1,3-butadiene, 16 benzene, 17 toluene, 18 n-propylbenzene, 19 cyclohexane and n-propylcyclohexane. 2,20 The reaction mechanism has a strong hierarchical structure; it is available from the author.…”

On the predictability of chemical kinetics for the description of the combustion of simple fuels

“…Dagaut and Hadj Ali (2003) built a detailed mechanism that consists of 827 reactions involving the kinetic of 112 chemical species. This mechanism was developed having as a basis the natural gas mechanisms of Dagaut (2002) and Dagaut et al (2000), and the iso-butane mechanism of Dagaut et al (1994). The validation of the Dagaut and Hadj Ali (2003) kinetics was performed using Jet Stirred Reactor (JSR) experiments at atmospheric pressure and for temperatures within the 950−1450 K range of the combustion of a mixture of 24.8% of iso-butane, 39% of n-butane and 36.2% of propane as being representative of a LPG.…”