Measurement of the Rate of Hydrogen Peroxide Thermal Decomposition in a Shock Tube Using Quantum Cascade Laser Absorption Near 7.7 μm

Hydrogen peroxide (H2O2) is formed during hydrocarbon combustion and controls the system reactivity under intermediate temperature conditions. Here, we measured the rate of hydrogen peroxide decomposition behind reflected shock waves using midinfrared absorption of H2O2 near 7.7 mu m. We performed the experiments in diluted H2O2/Ar mixtures between 930 and 1235K and at three different pressures (1, 2, and 10atm). Under these conditions, the decay of hydrogen peroxide is sensitive only to the decomposition reaction rate, H2O2 + M -> 2OH + M (k(1)). The second-order rate coefficient at low pressures (1 and 2atm) did not exhibit any pressure dependence, suggesting that the reaction was in the low-pressure limit. The rate data measured at 10atm exhibited falloff behavior. The measured decomposition rates can be expressed in Arrhenius forms as follows:k1(1 and 2 atm )=10(16.29 +/- 0.12)x exp (-21993 +/- 301/T)( cm 3 mol -1s-1)k1(10 atm )=10(15.24 +/- 0.10)x