High-temperature thermal decomposition of iso-octane based on reactive molecular dynamics simulations.

Branched alkanes are the major components of endothermic fuels used for advanced aircrafts. Reactive molecular dynamics (RMD) simulations are carried out to explore the detailed kinetic mechanism for the thermal decomposition of iso-octane widely used as the primary reference fuel of branched alkanes. The RMD calculations indicate that the initial decomposition mechanism of iso-octane is mainly through two pathways: (1) the C - C bond cleavage to produce smaller hydrocarbon radicals and (2) the hydrogen-abstraction reactions by small radicals including •H and •CH3. Most of the alkenes which are associated with the endothermic capacities in the iso-octane pyrolysis are produced from the C-C β-scission reactions of alkyl radicals. Propylene and ethylene are observed to be formed in large amounts. Kinetic parameters with the activation energy of 52.1 kcal mol-1 and pre-exponential factor of 7.2 × 1014 s-1, based on the first-order kinetic analysis, are in good agreement with previous work.