Renewable biodiesel is expected to contribute significantly toward meeting future energy demands in the transportation sector. Combustion properties (e.g., ignition, extinction, soot-formation, etc.) are governed by fundamental reaction mechanisms that can be elucidated from theoretical chemistry. We employ ab initio size-extensivity-corrected multireference correlated wavefunction approaches to predict chemically accurate reaction barriers and enthalpies for H-abstraction and �-scission processes that dominate fuel ignition and significantly determine product distributions. Specifically, we investigate H-abstractions by the five most important radicals (H�, CH3�, O�, HO2� and HO�) from methyl formate (the simplest surrogate for complex biodiesels) and their subsequent �-scission reactions. High-pressure-limit H-abstraction rate constants show reasonable agreement with experiments, and abstractions by HO� are thermodynamically and kinetically favored. Pressure-dependent �-scission reactions rate constants will be reported, and can be used to build detailed kinetic mechanisms. Importantly, these predicted rate constants suggest the need to revise current kinetics models.

Ab initio reaction kinetics of methyl formate hydrogen abstraction and subsequent β-scission

245th National Meeting (2013)

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