CO formation in the thermal decomposition of CH₃ONO at high temperatures: Kinetic modeling of the CH₃O decomposition rate

CH₃ONO was pyrolyzed in two different temperature regimes in order to determine the kinetics of the CH₃O decomposition reaction. A static reactor operating between 550 and 770 K was used for the first set of experiments, with analysis of products (CO, CH₂O, and CH₃OH) by FTIR absorption. In the second set of experiments, a shock tube operating in the range 1000-1600 K was employed and the CO product was measured by resonance absorption of the output of a stabilized CW CO laser. Kinetic modeling of CO product yields over the full range of temperature (550-1660 K) allowed us to obtain for the first time the rate constant for the decomposition of CH₃O: CH₃O + M → H + CH₂O + M (8), k₈ = (5.45 ± 0.63) × 10¹³ exp(-6794 ± 102/T) cm³/(mol·s), where M = Ar or He, and the error limits represent only the internal consistency of the modeled values. Theoretical implications of this result are discussed.