Experimental and kinetic modeling of the reduction of NO by isobutane in aJsr at 1 ATM

A kinetic study of the reduction of nitric oxide (NO) by isobutane in simul ated 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 1 450 K. Tn this new series of experiments, the initial mole fraction of NO w as 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, th e reduction of NO is favored when the temperature is increased and a maximu m NO reduction occurs slightly above stoichiometric conditions. The present results generally follow those reported in previous studies of the reducti on of NO by C-1 to C-3 hydrocarbons or natural gas as reburn fuel. A detail ed chemical kinetic modeling of the present experiments was performed using an updated and improved kinetic scheme (979 reversible reactions and 130 s pecies). An overall reasonable agreement between the present data and the m odeling was obtained. Furthermore, the proposed kinetic mechanism can be su ccessfully used to model the reduction of NO by ethylene, ethane, acetylene , a natural gas blend (methane-ethane 10:1), propane, and HCN. According to this study, the main route to NO reduction by isobutane involves ketenyl r adical. The model indicates that the reduction of NO proceeds through the r eaction path: iC(4)H(10) --> C3H6 --> C2H4 --> C2H3--> C2H2 --> HCCO; HCCO + NO --> HCNO + CO and HCN + CO2; HCNO + H --> HCN --> NCO --> NH; NH + NO --> N-2 and NH + H --> followed by N + NO --> N-2; NH + NO --> N2O followed by N2O + H --> N-2. (C) 2000 John Wiley & Sons, Inc.