ADSORPTION AND DECOMPOSITION OF ORGANOPHOSPHORUS COMPOUNDS ON NANOSCALE METAL-OXIDE PARTICLES - INSITU GC-MS STUDIES OF PULSED MICROREACTIONS OVER MAGNESIUM-OXIDE

Using an in situ pulse reactor GC-MS system, the thermal decomposition of organophosphorus compounds (as models of nerve agents) has been compared with their destructive adsorption on high surface area magnesium oxide. Dramatically lower temperatures are required when MgO is present. Volatile products evolved were formic acid, water, alcohols, and alkenes. At higher temperatures CO, CH4, and water predominated. Phosphorus residues remained completely immobilized. Addition of water enhanced the facility of MgO to destroy these compounds, and in fact, water pulses were found to partially regenerate a spent MgO bed. Using O-18 labeling, some aspects of the reaction mechanisms were clarified and in particular showed that oxygen scrambling occurred. Surface OH and MgO groups transferred oxygen in the formation of formic acid, and surface mobility and reactivity of adsorbed groups was very high. The substantial capacity of high surface area MgO for destruction and immobilization of such toxic substances makes it attractive for air purification schemes as well as solid reagents for destruction and immobilization of bulk quantities of hazardous phosphorus compounds or organohalides.