Effects of Methane and Ethane on the Heterogeneous Production of Water from Hydrogen and Oxygen over Platinum in Stagnation Flow

The effects of CH 4 and C 2 H 6 on the catalytic production of water from hydrogen-rich mixtures are investigated in a stagnation flow reactor using a combination of experimental and numerical methods. The analytical treatment assesses the accuracy of a detailed elementary reaction mechanism recently proposed for partial oxidation of ethane in short-contact-time reactors. Both CH 4 and C 2 H 6 inhibit the heterogeneous water-forming chemistry, as evidenced by a strong correlation between the net water production, light-off temperature, and mole fraction of hydrocarbon in the reactor. The effects of C 2 H 6 on Pt are more pronounced than those of CH 4, due to its propensity for forming carbonaceous overlayers on the catalyst surface. A general kinetic mechanism used successfully to describe partial oxidation of C 2 H 6 over Pt-impregnated monoliths could not reproduce the experimental observations. Discrepancies between model chemistry and experiment reveal possible avenues for the improvement of the mechanism.