Experimental and theoretical study on acetone pyrolysis in a jet-stirred reactor

Pyrolysis of acetone was investigated in a jet-stirred reactor coupled with on-line GC and GC-MS in the temperature range 700-1136 K at atmospheric pressure. Six species, namely 1-C4H8, iC(4)H(8), nC(4)H(10), iC(4)H(10), C5H6 and C6H6, were newly identified and quantified. A kinetic mechanism involving 296 species and 1836 reactions, including subsets of acetone and 2-butanone, was developed with reasonable predictions against the experimental data. C-C bond cleavage releasing CH3CO and CH3 radicals is the chain-initiation and the most intensively promoting reaction for the consumption of acetone. Its high-pressure limit rate constant was recalculated as k(1) = 1.12 x 106.T-3.84.exp(-78.6 kcal mol(-1)/RT) at the CBS-QB(3) level. Besides this step, H- and CH3-abstractions of acetone by CH3 radical, with the calculated high-pressure limit rate constant as k(4) = 1.38.T-3.49.exp(-8.58 kcal mol(-1)/RT) and k(7) = 5.70.T-3.96.exp(-41.7 kcal mol(-1)/RT), respectively, govern the major consumption routes of acetone. CH3 radicals contribute as the key species to the production of the major hydrocarbons such as CH4, C2H4 and C2H6, and minor branches to benzene and C2H5COCH3. Moreover, the present kinetic mechanism could predict fairly the mole fractions of the gas species in the high-temperature pyrolysis of acetone and the ignition delay times of acetone at different temperature and pressure region, which indicates the applicability of this model in a wide-range condition.