Characteristics of Magnesium Combustion Products Governing Their Effectiveness to Decompose DIMP (Diisopropyl Methylphosphonate), a Nerve-Agent Surrogate

Abstract

Burning magnesium powders in an enclosed vessel in different gas mixtures yielded condensed products with different properties. In separate experiments, these product powders, as well as reference materials including commercial calcined MgO powders, were loaded in a flow reactor, where they were exposed to vapors of diisopropyl methylphosphonate (DIMP), a nerve agent surrogate. The reactor was operated at 200 °C. It was studied experimentally how the characteristics of combustion products influence their effectiveness in decomposing DIMP. The gaseous DIMP decomposition products were characterized using fourier transform infrared spectroscopy (FTIR). A relative effectiveness of DIMP decomposition was introduced by comparing the materials to a calcined MgO based on either the mass or surface area of the test sample. Characterization of the as-prepared and DIMP-exposed powders involved X-ray diffraction, thermogravimetry, and Attenuated Total Reflectance (ATR)-FTIR. The combustion-derived powders decomposed DIMP more effectively compared to commercial calcined MgO. Powders that decomposed DIMP vapors most effectively had larger crystallite sizes and were least covered by CO2, which poisoned the MgO surface, preventing it from interacting with DIMP.