Experimental and Kinetic Modeling Study of the Effect of NO and SO2 on the Oxidation of CO-H2 Mixtures

The effect of NO and SO2 on the oxidation of a CO—H2 mixture was studied in a jet-stirred reactor at atmospheric pressure and for various equivalence ratios (0.1, 1, and 2) and initial concentrations of NO and SO2 (0–5000 ppm). The experiments were performed at fixed residence time and variable temperature ranging from 800 to 1400 K.

Additional experiments were conducted in a laminar flow reactor on the effect of SO2 on CO—H2 oxidation in the same temperature range for stoichiometric and reducing conditions. It was demonstrated that in fuel-lean conditions, the addition of NO increases the oxidation of the CO—H2 mixture below 1000 K and has no significant effect at higher temperatures, whereas the addition of SO2 has a small inhibiting effect.

Under stoichiometric and fuel-rich conditions, both NO and SO2 inhibit the oxidation of the CO—H2 mixture. The results show that a CO—H2 mixture has a limited NO reduction potential in the investigated temperature range and rule out a significant conversion of HNO to NH through reactions like HNO + CO ⇔ NH + CO2 or HNO + H2 ⇔ NH + H2O.

The chain terminating effect of SO2 under stoichiometric and reducing conditions was found to be much more pronounced than previously reported under flow reactor conditions and the present results support a high rate constant for the H + SO2 + M ⇔ HOSO + M reaction. The reactor experiments were used to validate a comprehensive kinetic reaction mechanism also used to simulate the reduction of NO by natural gas blends and pure C1 to C4 hydrocarbons. © 2003 Wiley Periodicals, Inc.

Int J Chem Kinet 35: 564–575, 2003