DFT study of Oxidation Initiation for Different Compound in Gasoline

A DFT study of oxidation initiation reaction for same carbon number but different type hydrocarbon compound in gasoline was performed. Firstly, the homolytic dissociation energies of the C-H bond in various hydrocarbon molecules were calculated and the C-H active site which was most likely to be attacked by oxygen molecules was obtained. Then, the reaction barrier of oxidation initiation reaction for different gasoline hydrocarbon molecules was compared. Furthermore, frontier orbital theory was used to analyze the chain initiation mechanism. It was found that the symmetry and energy gap of the HOMO orbitals of gasoline hydrocarbon molecules and the LUMO orbitals of oxygen molecule are the decisive factors in the oxidation initiation reaction. The results indicate that the reaction barrier of the olefin is much lower than other hydrocarbons. On the other hand, the energy gap between the HOMO orbital of 2, 4-hexadiene and the LUMO orbital of the oxygen is much lower than other molecules just followed by 1-hexene.