Spark-ignited explosions in chilled vessels. Part 3.—Methane + oxygen explosions, and the mechanism of hydrogen peroxide formation in H₂and CH₄explosions

Abstract

The chilling technique described earlier (part 1) has been used in an attempt to isolate methyl hydroperoxide from methane + oxygen explosions. Considerable evidence was obtained that a trace of this compound may be present in the products, but the results were not easy to reproduce. It is concluded that while CH300H. is not an important intermediate in the slow oxidation of methane, it may occur in processes of very short duration, such as explosions. or "knock" in engines. The formation of hydrogen peroxide has also been examined, and complicated relationships have been obtained. The mechanism of formation of hydrogen peroxide in explosions both of hydrogen and of methane is discussed in detail. The general indications are that gas-phase processes in the cooling gases lead to peroxide formation at the higher pressures, while reactions involving the surface become more important with decreasing pressure. The role of Pyrex, ice and boric-acid-coatings is also considered.The participation of the radical CH3COO. in combustion processes has been viewed with disfavour by several authors 1 on the grounds of its instability when formed in the association reaction CH3. + 0 2 -+ CH3OW.