Decomposition of DIMP Vapors Interacting with Metal Oxides

Finely dispersed metal oxide particles form as a result of combustion of many energetic formulations; such particles are expected to catalyze decomposition of toxic vapors of chemical weapon agents (CWA), such as sarin. The thermal decomposition of CWA vapors is very fast at high temperatures; however, as the temperatures approach the CWA boiling point (~200 C), the rate of thermal decomposition drops. Thus, for the temperature ranges of 200 – 500 C, the effect of condensed combustion products catalyzing CWA decomposition are expected to be most important. The reactions and processes involved are poorly understood. Here, such reactions are studied using DIMP as a surrogate of sarin. DIMP is introduced into a heated laminar flow system and interacts with a porous plate pre-loaded with fine powders of different metal oxides. The initial concentration of DIMP in air or in nitrogen is adjusted to 3 µmol/L. The concentration of DIMP in the flow passed through the plate is measured using a total gas analysis unit of an FTIR analyzer. Both flow system and the porous plate are heated to temperatures between 200 and 350 C; the flowrate of air is varied. Metal oxides exposed to DIMP-bearing flow are recovered and analyzed using FTIR-ATR. Results will be presented and discussed for several metal oxides typically generated by energetic materials, including gamma-alumina, magnesium oxides, etc.