High pressure oxidation of C2H4/NO mixtures

Abstract

An experimental and kinetic modeling study of the interaction between C 2 H 4 and NO has been performed under flow reactor conditions in the intermediate temperature range (600-900 K), high pressure (60 bar), and for stoichiometries ranging from reducing to oxidizing conditions. The main reaction pathways of the C 2 H 4 /O 2 /NO x conversion, the capacity of C 2 H 4 to remove NO, and the influence of the presence of NO x on the C 2 H 4 oxidation are analyzed. Compared to the C 2 H 4 /O 2 system, the presence of NO x shifts the onset of reaction 75-150 K to lower temperatures. The mechanism of sensitization involves the reaction HOCH 2 CH 2 OO + NO → CH 2 OH + CH 2 O + NO 2 , which pushes a complex system of partial equilibria towards products. This is a confirmation of the findings of Doughty et al. [Proc. Combust. Inst. 26 (1996) 589-596] for a similar system at atmospheric pressure. Under reducing conditions and temperatures above 700 K, a significant fraction of the NO x is removed. This removal is partly explained by the reaction C 2 H 3 + NO → HCN + CH 2 O. However, a second removal mechanism is active in the 700-850 K range, which is not captured by the chemical kinetic model. With the present thermochemistry and kinetics, neither formation of nitro-hydrocarbons

Experiments and simulations of NOx formation in the combustion of hydroxylated fuels

“…It was also observed that a significant amount of NO can participate in a recycle loop with HCNO through HCCO, especially when a significant portion of the oxidation pathway is through HCCO as discussed in Section 3.3.2. Several different groups have also observed that removal of NO can occur through reaction with HCCO and vinyl radical [39,23]. This loop is shown in reactions (11)-(15) below:…”

“…The NO x sub-mechanism includes all relevant N-containing reactions of GRI-Mech 3.0 [21], Dagaut et al [22] and Giménez-López et al [23], including mechanisms for: thermal NO, prompt NO, N 2 O, NNH, nitro-hydrocarbons, and nitroso-compounds. The prompt-initiating reaction of Fenimore [24,25] used in the GRI-Mech 3.0 shown in reaction (2) has been shown to be spin forbidden by Moskaleva and Lin [26].…”

“…Rates for this reaction and the NCN sub-mechanism are from Giménez-López et al [23]. It has been shown that even after replacing the HCN initiating reaction with the NCN reaction, HCN remains a significant contributor to NO formation [22,10].…”

“…9. Additionally, the increase in HCN formation, especially in the rich regions, increases the potential for NO removal through the NO!HCN!N 2 mechanism [35][36][37][38][39]23].…”

Modeling Nitrogen Species as Pollutants: Thermochemical Influences

“…To this end, the use of chemical kinetic models has been invaluable, and in recent years there have been quite a few proposed mechanisms concerned with NO x chemistry, and with interactions of nitrogen oxides with hydrocarbons. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] However, as will be discussed, there can be significant disparity between published models in terms of the thermochemical properties of nitrogen-containing species therein.…”