The formation of propene gas during PC decomposition has been demonstrated in previous simulations and experimental measurements as well as in our study, as shown in the GC section . While the formation of excess oxygen is far from impossible due to the presence of oxygen-rich perchlorate, this reaction mechanism would result in carbon dioxide, which our experiments do not detect, ruling out this reaction path. A second possibility is the chlorination of propene gas, leading to a follow-up reaction with a sodium oxide surface. An equivalent reaction mechanism for ethylene oxide is