Towards high-level theoretical studies of large biodiesel molecules: an ONIOM [QCISD(T)/CBS:DFT] study of hydrogen abstraction reactions of C(n)H(2n+1)COOC(m)H(2m+1) + H.
Recent interest in biodiesel combustion urges the need for the theoretical chemical kinetics of large alkyl ester molecules. This is, however, computationally challenging for prevalent high-level electronic structure theory based methods. The hydrogen abstraction reactions of alky esters CnH2n+1COOCmH2m+1 (n = 1-5, 9, 15; m = 1, 2) by a hydrogen radical were investigated by a computational technique based on a two-layer ONIOM method, employing a QCISD(T)/CBS method for the high layer and a DFT method for the low layer. The calculated energy barriers and heats of reaction, using the ONIOM method with a minimum of the required chemically active portion, are in very good agreement with those obtained using the widely accepted high-level QCISD(T)/CBS theory because the computational errors were less than 0.1 kcal mol(-1) for all the tested cases. The ONIOM[QCISD(T)/CBS:DFT] method provides a computationally accurate and affordable approach to the high-level theoretical chemical kinetics of large biodiesel molecules.
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong. pengzhang.zhang@polyu.edu.hk.
Lidong
L
Zhang
Peng
P
Zhang
D056804:Biofuels / Q000032:analysis*; D006358:Hot Temperature; D006838:Hydrocarbons / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D011789:Quantum Theory; D013816:Thermodynamics
D056804:Biofuels; D006838:Hydrocarbons