FTIR and mass-spectrometric measurements of the rate constant for the C₆H₅ + H₂ reaction

The rate constant for the C₆H₅ + H₂ → C₆H₆ + H reaction has been measured by pyrolysis/Fourier transform infrared spectrometry (P/FTIRS) in the temperature range of 548-607 K and by pulsed-laser photolysis/ mass spectrometry (PLP/MS) in the temperature range of 701-1017 K. By P/FTIRS, the reaction was studied by measuring time-resolved concentration profiles of the reactant (C₆H₅NO) and the product (C₆H₆) using highly diluted mixtures of C₆H₅NO in H₂ (with or without Ar dilution). In PLP/MS experiments, the C₆H₅ radical was generated by the photolysis of C₆H₅COCH₃ at 193 nm in the presence of several Torr of H₂. The C₆H₅ + H₂ rate constant was determined by the absolute yields of C₆H₆ and C₆H₅CH₃ products. The results of these two spectrometric measurements agree closely with our theoretically predicted expression, k = 5.72 × 10⁴T^2.43 exp (-3159/7) cm³/(mol·s) and with that of a shock-tube study by Troe and co-workers (ref 20) in the temperature range of 1050-1450 K. Preliminary kinetic data on the CH₃ + C₆H₅ association reaction are also presented.