Co-oxidation of methylphosphonic acid and ethanol in supercritical water (original) (raw)

A supercritical water co-oxidation elementary reaction rate mechanism was constructed from submechanisms for methylphosphonic acid (MPA or PO(OH) 2 CH 3 ) and ethanol with updated kinetic rate parameters for H 2 O 2 and HOCO • chemistry. The co-oxidation mechanism accurately reproduces the experimentally observed conversion trend of the refractory MPA component as a function of initial concentration of the labile ethanol component [J.M. Ploeger, P.A. Bielenberg, R.P. Lachance, J.W. Tester, Co-oxidation of methylphosphonic acid and ethanol in supercritical water: I. Experimental results, J. Supercrit. Fluids ]. The increase in MPA conversion with increasing ethanol concentration is predicted to be caused by the increased concentration of hydroperoxy radicals (HO 2 • ) produced by ethanol oxidation. An analysis of the major organophosphorus reaction fluxes indicated that the co-oxidative effect would increase the conversion of MPA but not change the rate of formation of methane. An experiment using a model formaldehyde/methanol mixture as a co-oxidant was conducted to confirm this prediction.