A KINETIC-STUDY ABOUT THE REACTIONS OF NH2((X)OVER-TILDE(2)B(1)) RADICALS WITH SATURATED-HYDROCARBONS IN THE GAS-PHASE

The reactions of NH2 (($) over tilde X(2)B(1)) with the hydrocarbons methane (1), ethane (2) and propane (3) were investigated behind incident shock waves at temperatures between 1500 K and 2100 K. The decay of NH2 was measured by laser absorption. NH2 was formed by the thermal decomposition of hydrazine. The following rate constants were obtained for the temperature range mentioned: k(1) = (1.2 +/- 0.6). 10(13) exp (-(63.4 +/- 3.4) kJ/mol/RT) cm(3) mol(-1) s(-1) k(2) = (9.7 +/- 0.3). 10(12) exp (-(48.0 +/- 1.8) kJ/mol/R T) cm(3) mol(-1) s(-1) k(3) = (1.7 +/- 0.4). 10(13) exp (-(44.6 +/- 2.0) kJ/mol/RT) cm(3) mol(-1) s(-1). These measurements extend the results obtained at low temperatures by Demissy and Lesclaux (330K-250K) and by Hack et al. (400K- 1080K) into the range of interest for combustion processes. The apparent energies of activation fit rather well into an Evans Polanyi plot. They correlate with the energies of activation of the corresponding reactions of OH(X(2)II) and those of CH3(($) over tilde X(2)A(2)('')) radicals.