Determination of the Rate Coefficients of the CH4 + O2 → HO2 + CH3 and HCO + O2 → HO2 + CO Reactions at High Temperatures

Rate coefficients of the title reactions, R-1 (CH4 + O-2 -> HO2 + CH3) and R-2 (HCO + O-2 -> HO2 + CO) were obtained over T = 1610 - 1810 K and T = 200 - 1760 K, respectively, and at rho = 7.1 mu mol/cm(3). A lean CH4/O-2/Ar mixture (0.1% CH4, Phi = 0.02) was heated behind reflected shock waves and the temporal OH absorption profiles were measured using a laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the experimental profiles via optimization of K-1 and k(2) values in the reaction simulation. The rate coefficient expressions derived are k(1) = 1.46 x 10(14) exp (-26 210 K/T) cm(3)/mol/s, T = 1610 - 1810 K and k(2) = 1.9 x 10(12) T-0.176 exp (-245 K/T) cm(3)/mol/s, T=200 similar to 1760 K.