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

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 gamma -Al(2)O(3) supported Rh and Ru catalysts at 500-600 degreesC. It was found that CO is the primary product for the reaction of CH(4)/O(2)/He (2/1/45) gas mixture over Hz 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/gamma -Al(2)O(3) and Ru/SiO(2) catalysts. The dominant reaction pathway of CO formation over Ru/gamma -Al(2)O(3) and Ru/SiO(2) catalysts is via the reforming reactions of CH(4) with CO(2) and H(2)O. The effect of space velocity on the partial oxidation of methane over SiO(2) and gamma -Al(2)O(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/gamma -Al(2)O(3) catalysts. (C) 2000 Elsevier Science B.V. All rights reserved.