MECHANISM REDUCTION FOR TROPOSPHERIC CHEMISTRY - BUTANE OXIDATION

A detailed butane oxidation mechanism for the troposphere was reduced using objective methods. The reductions of this large scheme have been based on sensitivity analysis over a wide range of atmospheric condit ions, characterised by extremely low, intermediate and high [NOx]. The quasi-steady-state approximation (QSSA) was applied to reduce further the number of differential (rate) equations needed to describe the ki netics. Significant simplifications were achieved leading to reduction s in the number of differential equations of a factor of 6-10, dependi ng on the conditions. The reductions lead to a greater transparency in the mechanism and to a more facile identification of key reaction rou tes. This facility is demonstrated via a discussion of secondary route s to HO2 via carbonyl photolysis.