Spontaneous ignition of methane—air mixtures at high pressure II—the explosive region of reaction

Abstract

The rates of temperature and pressure rise during spontaneous ignition at initial pressures up to 110 atmospheres have been followed for relatively slow explosions of rich mixtures of methane and air. The activation energy for the reaction in the initial stages of explosion was 20 to 25 kcal/mole. The reaction rate was relatively independent of pressure above 63 atmospheres and was approximately proportional to the square of the oxygen mole fraction. Explosion products include relatively large amounts of hydrogen and ethane. It is suggested that the marked differences between the reaction during the ignition delay and that during explosion are due to a take-over of control of the reaction by hydrogen atom reactions. In consequence, the fast reaction has characteristics typical of an oxidation-sensitized pyrolysis.