Experimental Measurements and Kinetic Modeling of CO/H2/O2/NOx Conversion at High Pressure

This paper presents results from lean CO/H2/O2/NOx oxidation experiments conducted at 20–100 bar and 600–900 K. The experiments were carried out in a new high-pressure laminar flow reactor designed to conduct well-defined experimental investigations of homogeneous gas phase chemistry at pressures and temperatures up to 100 bar and 925 K.

The results have been interpreted in terms of an updated detailed chemical kinetic model, designed to operate also at high pressures. The model, describing H2/O2, CO/CO2, and NOx chemistry, is developed from a critical review of data for individual elementary reactions, with supplementary rate constants determined from ab initio CBS-QB3 calculations.

New or updated rate constants are proposed for important reactions, including OH + HO2 ⇋ H2O + O2, CO + OH ⇋ [HOCO] ⇋ CO2 + H, HOCO + OH ⇋ CO + H2O2, NO2 + H2 ⇋ HNO2 + H, NO2 + HO2 ⇋ HONO/HNO2 + O2, and HNO2(+M) ⇋ HONO(+M). Further validation of the model performance is obtained through comparisons with flow reactor experiments from the literature on the chemical systems H2/O2, H2/O2/NO2, and CO/H2O/O2 at 780–1100 K and 1–10 bar.

Moreover, introduction of the reaction CO + H2O2 → HOCO + OH into the model yields an improved prediction, but no final resolution, to the recently debated syngas ignition delay problem compared to previous kinetic models. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 454–480, 2008