APPLICATION OF AB INITIO QUANTUM MECHANICAL CALCULATIONS TO INVESTIGATE OXIDATION OF C-7 AND C-14 METHYL ESTERS: AN ALTERNATIVE FUEL

Using Gaussian 03 [1] program the electronic structure of the C-14 methyl ester, C14H28O2 (methyl tridecanoate), one of the components of biodiesel and the species involved in the unimolecular and bimolecular decompositions of it were estimated. For the electronic calculations the density functional theory (DFT) at B3LYP/6-311G(d,p) level and complete basis set (CBS-QB3) were applied. Using the KHIMERA program [2], contributions from energies, harmonic vibrational frequencies and moments of inertia were utilized to construct modified Arrhenius rate expressions for bimolecular reactions. C7H14O2 was selected as a surrogate for the C14H28O2 fuel in order to study the bimolecular reactions with flame radicals. In the present work reactions of carbons number 5 and 6 of C7H14O2, where carbon number 1 is the one single bonded to oxygen atom, with flame reactive radicals such as CH3, HO2 and H were studied. The rate expressions for the cited reactions were estimated using transition state theory as implemented in KHIMERA, over the temperature 500-2000 K. Heat of reactions for unimolecular decompositions were also calculated and compared to those from Methyl Butanoate (MB).