Shock Tube Measurement of the C₂H₄ + H ⇔ C₂H₃ + H₂ Rate Constant

The rate constant for the reaction C₂H₄ + H ⇔ C₂H₃ + H₂ was studied behind reflected shock waves at temperatures between 1619 and 1948 K and pressures near 10 atm in a mixture of C₂H₄, CH₄, H₂, and argon. C₂H₄ time histories were measured using laser absorption of a CO₂ gas laser near 10.53 μm. Experimental mixtures were designed to optimize sensitivity to the title reaction with only weak sensitivity to secondary reactions. Two mechanisms, FFCM1 and ARAMCO v2, are used for data analysis. The well-selected operating conditions and Monte Carlo sampling data analysis procedure resulted in mechanism-independent reaction rate constant measurements with a 2σ uncertainty of ±35%. The current data disagree with a broadly used theoretical calculation (Knyazev et al. (1996)), but they are in good consensus with one of the review studies (Baulch et al. (2005)), k = (3.9 × 10²²) T^3.62 exp(-5670/ T) cm³ molecule^-1 s^-1. To the best of our knowledge, this work provides the first high-temperature study of the C₂H₄ + H ⇔ C₂H₃ + H₂ reaction rate constant with well-defined uncertainty.