Rational modeling of the CPO of methane over platinum gauze: Elementary gas-phase and surface mechanisms coupled with flow simulations

The high-temperature catalytic partial oxidation of methane (CPOM) over a platinum gauze reactor was modeled by integrating 3D numerical simulations of the flow field coupled with heat transport as well as detailed micro-kinetic models including gas-phase and surface reaction mechanisms. Model results describe well CPO experiments over Pt-gauzes in the literature. The conversions of CH₄ and O₂ increase with an increased contact time and were constant in the temperature range of 1000–1200 K. The selectivity to CO linearly increases with temperature. H₂ was only observed above 1200 K, below this temperature H₂O was the only hydrogen-containing product. The contribution of heterogeneous steps in the overall process is prominent, but in the later stages of the reactor, gas-phase reactions become important at certain conditions of temperature, pressure and residence time. Simulations predicted significant gas-phase production of ethane and ethylene via methane oxidative coupling upon increasing the total pressure and residence time. Consequently, homogeneous and heterogeneous processes should be simultaneously implemented in order to accomplish a solid reactor modeling.