High pressure oxidation of C2H4/NO mixtures

An experimental and kinetic modeling study of the interaction between C2H4 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 C2H4/O2/NOx conversion, the capacity of C2H4 to remove NO, and the influence of the presence of NOx on the C2H4 oxidation are analyzed. Compared to the C2H4/O2 system, the presence of NOx shifts the onset of reaction 75–150 K to lower temperatures. The mechanism of sensitization involves the reaction HOCH2CH2OO + NO → CH2OH + CH2O + NO2, which pushes a complex system of partial equilibria towards products. This is a confirmation of the findings of Doughty et al. [3] for a similar system at atmospheric pressure. Under reducing conditions and temperatures above 700 K, a significant fraction of the NOx is removed. This removal is partly explained by the reaction C2H3 + NO → HCN + CH2O. 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 (CH3NO2, C2H3NO2, C2H5NO2, CHOCH2NO2) nor nitroso-compounds (CH3NO, C2H3NO, C2H5NO, ONCH2CHO, CH3C(O)NO, ONCH2CH2OH) contribute to remove NOx.