FTIR and Mass-Spectrometric Measurements of the Rate Constant for the C6H5 + H2 Reaction

The rate constant for the C 6 H 5 + H 2 → C 6 H 6 + 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 (C 6 H 5 NO) and the product (C 6 H 6 ) using highly diluted mixtures of C 6 H 5 NO in H 2 (with or without Ar dilution). In PLP/MS experiments, the C 6 H 5 radical was generated by the photolysis of C 6 H 5 COCH 3 at 193 nm in the presence of several Torr of H 2 . The C 6 H 5 + H 2 rate constant was determined by the absolute yields of C 6 H 6 and C 6 H 5 CH 3 products. The results of these two spectrometric measurements agree closely with our theoretically predicted expression, k = 5.72 × 10 4 T 2.43 exp (−3159/ T ) cm 3 /(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 CH 3 + C 6 H 5 association reaction are also presented.