Modeling ozone formation from alkene reactions using the Carbon Bond chemical mechanism

Predictions of ozone formation, due to oxidation of alkenes in presence of NOx, generated by the Carbon Bond 2005 (CB05) and CB05-TU (CB05 with an updated toluene scheme) condensed chemical mechanisms were tested by simulating 138 environmental chamber experiments carried out in 7 different environmental chambers and by running box modeling with four cases. CB05 and CB05-TU reasonably simulated ozone formation from propene under typical urban conditions and for cases with moderately elevated propene concentrations. Chamber simulations of 47 propene – NOx and 5 isobutene – NOx experiments and box modeling for four cases (1 for propene and 3 for isobutene) showed that the performance of CB05 and CB05-TU in simulating ozone formation from propene and isobutene can be improved by modeling propene and isobutene using the new condensed reactions for propene and isobutene developed in this work. The results of this study indicate that the capability of condensed chemical mechanisms in simulating ozone formation can be improved by (1) examining the relative importance of VOCs based on their emissions and reactivity, (2) separately representing relatively important VOCs in the mechanism, (3) modeling less important compounds using reactions of lumped model species shared by multiple compounds, and (4) evaluating mechanisms with experimental data such as environmental chamber data.