Mechanism of Ozone Formation in the Silent Electric Discharge

Abstract

The kinetics of ozone formation from oxygen have been studied in a Siemens ozonizer. Measurements were made at pressures from 70 to 400 mm and temperatures from −30° to −100°C. The results suggest that oxygen atoms, produced in the discharge, both form ozone by three body collisions with oxygen molecules and also destroy it, leading to a steady‐state ozone concentration at sufficiently long residence times. The ratio of rate constants for these two reactions, and their activation energy difference, are similar to those found by Eucken and Patat in the photolysis of oxygen. At the higher temperatures, thermal ozone decomposition becomes an important factor in determining the steady‐state ozone concentration. The variation of steady‐state ozone concentration with pressure suggests that the combination of oxygen atoms and molecules to form ozone changes from termolecular to bimolecular in the pressure range investigated. The lifetime of the activated ozone complex, thus measured, is of the expected order of magnitude for the number of vibrational degrees of freedom involved. The possible role of other ozone destruction reactions is also considered.