A chemical kinetic study of tertiary-butanol in a flow reactor and a counterflow diffusion flame

The combustion chemistry of tertiary-butanol is studied experimentally in a high pressure flow reactor and in counterflow diffusion flames. Princeton Variable Pressure Flow Reactor results show that t-butanol does not exhibit low temperature chemistry, and thus has no negative temperature coefficient behavior under the studied conditions. The onset of gas phase chemistry at high pressure occurs at ~780. K. Over the temperature range of 780-950. K, t-butanol primarily reacts through hydrogen abstraction - alkyl or alkoxy radical beta-scission pathways to form methyl and propen-2-ol, which likely tautomerizes in the sampling system to form acetone. A species sampling study of a t-butanol counterflow diffusion flame reveals that the high temperature consumption routes of t-butanol lead to the stable intermediates isobutene, acetone, and methane, with isobutene existing in the highest concentrations. The extinction limits of t-butanol, isobutene, acetone, and methane diffusion flames are also reported. On a transport-weighted enthalpy basis, t-butanol extinguishes more readily than any of its primary intermediates, signifying that it is kinetically less resistant to extinction than the products of its initial reactions. Numerical simulation of these t-butanol flames reveals that the isobutene and acetone chemistry sub-models significantly affect the computed extinction limits. Improvement in the current understanding of isobutene oxidation kinetics, in particular, appears necessary to developing reliable kinetic models for t-butanol combustion.