Upper Limit for the Methane-Oxygen Initiation Reaction in the Presence of Iodine-131 Behind Reflected Shock Waves

摘要

A one-inch diameter single-pulse shock tube was used to study the rate of methyl iodide formation from 815 to 1151K via the reaction CH sub 4 + I implies CH sub 3 + HI with the observed rate constant k sub 40 = 10 exp 14 exp 5 exp(-33.7/RT) cm exp 3 /mole sec. Tracer quantities of iodine-131 were used to follow the course of the reaction. At 1097K in a stoichiometric methane-oxygen reaction mixture with small amounts of iodine present, the methane-oxygen initiation reaction, CH sub 4 + O sub 2 implies CH sub 3 + HO sub 2 , was not found to occur, thus putting an upper limit on the rate constant k sub 2 = 9.53 x 10 exp 5 cm exp 3 /mole s. Mass-spectral analysis of the reaction products from the above experiment indicated that formaldehyde was formed; at 1097K oxygen was able to successfully compete with iodine for methyl radicals. The rate constant for the reaction, CH sub 3 + O sub 2 implies CH sub 2 O + OH, was found to be k sub 4 = 3.96 x 10 exp 10 cm exp 3 /mole s. (ERA citation 09:018883)