Mechanistic study of partial oxidation of methane to synthesis gas over supported rhodium and ruthenium catalysts using in situ time-resolved FTIR spectroscopy

Abstract

In situ time-resolved FTIR spectroscopy was used to study the reaction mechanism of partial oxidation of methane to synthesis gas and the interaction of CH 4/O 2/He (2/1/45) gas mixture with adsorbed CO species over SiO 2 and γ-Al 2O 3 supported Rh and Ru catalysts at 500–600°C. It was found that CO is the primary product for the reaction of CH 4/O 2/He (2/1/45) gas mixture over H 2 reduced and working state Rh/SiO 2 catalyst. Direct oxidation of methane is the main pathway of synthesis gas formation over Rh/SiO 2 catalyst. CO 2 is the primary product for the reaction of CH 4/O 2/He (2/1/45) gas mixture over Ru/γ-Al 2O 3 and Ru/SiO 2 catalysts. The dominant reaction pathway of CO formation over Ru/γ-Al 2O 3 and Ru/SiO 2 catalysts is via the reforming reactions of CH 4 with CO 2 and H 2O. The effect of space velocity on the partial oxidation of methane over SiO 2 and γ-Al 2O 3 supported Rh and Ru catalysts is consistent with the above mechanisms. It is also found that consecutive oxidation of surface CO species is an important pathway of CO 2 formation during the partial oxidation of methane to synthesis gas over Rh/SiO 2 and Ru/γ-Al 2O 3 catalysts.