Kinetics of pyrolysis of octane in argonhydrogen mixtures

Abstract

The pyrolysis kinetics of n-octane dilute in both argon and 50 mol% mixtures of argon and hydrogen have been studied in the temperature range 1000–1400K in a single-pulse shock tube. In the inert gas pyrolyses principal products of reaction are ethylene, methane, and propene. Yields of methane and ethane are increased in pyrolyses in 50 mol% mixtures of argon and hydrogen and the rate of decomposition of octane is approximately an order of magnitude larger than that in inert gas pyrolyses. Methyl radical and hydrogen atom attack on the parent octane determines the octane decomposition kinetics and methyl, and ethyl radical attack on hydrogen have been found to be important in determining product distributions in pyrolyses containing hydrogen. Both overall kinetics and product distributions can be simulated by a reaction model based on a modified Kossiakoff-Rice mechanism involving coupled isomerization and unimolecular decomposition of large alkyl radicals.