Modeling the temperature and pressure dependence of the reaction HO+CO ixHOCO ixH+CO 2

Abstract

The bimolecular reaction HO+CO ixH+CO2 involves the intermediate formation of HOCO. As a consequence, the rate coefficient shows a complicated temperature and pressure dependence. An optimized E- and J-resolved rigid activated complex RRKM theory, with simplified E- and J-resolved pressure-dependent collision efficiencies, fits the available experimental data and allows for extrapolations to unexplored conditions. Experiments between 80 and 2370 K, between 10−3 and 103 bar in the bath gas He, and below 1 bar in Ar, N2, CF4 SF6, and H2O at 298 K, serve as the database. A limiting low-pressure rate constant for HO removal of ko=[1.0×1013 exp(−8050 K/T)+9.0×1011 exp(−2300 K/T)+1.01×1011 exp (−30 K/T)] cm3 mol−1 s−1 and a limiting high-pressure rate constant of k∞=[1.23×1015 exp (−7520 K/T)+1.1×1013 exp(−1850 K/T)+8.0×1011 exp(−120 K/T] cm3 mol−1 s−1 will reproduce the results. The pressure dependence of the rate coefficient as a function of the temperature is represented for the bath gases He, Ar, N2, CF4, SF6, and H2O. Rate coefficients for HOCO formation and HOCO dissociation are also given.