The Oxidation of Allene in a Low-Pressure H₂ / O₂ / Ar-C₃ H₄ Flame

ABSTRACT

We have studied the oxidation of allene in a rich ( φ = 1.5), low-pressure H₂/O₂/Ar flame to which one percent altene was added. Temperatures were measured by thermocouple and by OH laser-induced fluorescence. Stable species profiles were determined from mass spectrometer measurements using a quartz microprobe, and OH concentrations were determined using LIF. The experiments were analyzed with the aid of a chemical kinetic model. Significant quantities of methane and acetylene are formed early in the flame as a consequence of recombination of propargyl with hydrogen atoms,

H + C₂H₃ (+ M) ↔ C₃H₄P

H + C₃H₄P ↔CH₃ + C₂H₂

H+CH₃( + M) ↔ CH₄( + M),

where C₃H₄P is propyne. However, the main oxidation path appears to be

C₂H₃ + H↔ C₂H₂ + H₂

C₃H₂ + O₂ ↔ products

The underlying flame chemistry is discussed in depth, including the thermochemistry and molecular structure of various C₃,H₂ isomers.