A quantum chemistry study on reaction mechanisms of SO2 with O3 and H2O2

Reaction mechanisms of SO2 with O-3 and H2O2 were investigated using quantum chemistry ab initio methods. Structures of all reactants, products, and transition states were optimized at the B3LYP/6-311G+(3df,2p) level, and energy calculations were made at the G2M level. SO2 reactions with O-3 and H2O2 occurred by O-abstraction and OH-abstraction by SO2, respectively, at length forming SO3+O-2 (I-3 pound (g) (-) ) and H2SO4. For SO2+O-3 reactions the barrier height was predicted to be 9.68 kcal/mol with a rate constant of 3.61x10(-23) cm(3)/(molecule center dot s) at 300 K, which is below the experimental upper limit. The rate constant predicted for this reaction accords well with the one provided by National Institute for Standards and Technology (NIST) in 250 similar to 500 K. For SO2+H2O2 reactions the barrier height was predicted to be 62.39 kcal/mol with a rate constant of 2.48x10(-61) cm(3)/(molecule center dot s) at 300 K.