Catalytic partial oxidation of methane over Pt/ceria-doped catalysts: Effect of ionic conductivity

Catalyst deactivation due to carbon deposition during the production of hydrogen rich synthesis gas has proven to be a major impediment in hydrocarbon fuel reforming. Several Pt-deposited catalysts were prepared and tested to study the role of ionic conductivity of the support material upon which they were deposited. Ceria-based supports used in this work were synthesized by a hydrothermal method and the catalysts were prepared by Pt addition (1 wt.%). Characterization of ceria-based supports included composition, surface area, crystal phases, reducibility and ionic conductivity. In order to study the influence of ionic conductivity on carbon deposition, Pt/(Ce0.56Zr0.44)O2−x, Pt/(Ce0.91Gd0.09)O2−x, Pt/(Ce0.71Gd0.29)O2−x and Pt/CeO2 were utilized as catalysts in the conversion of methane to syn-gas at varying oxygen-to-carbon ratios. Carbon content on the catalysts measured post-test revealed that the gadolinium-doped catalysts generated less carbon deposition between the catalysts tested. Stability tests of Pt/ceria-based catalysts showed stable performance during a 24 h reaction period. In order to compare carbon formation by oxygen ion conducting and non-oxygen ion conducting catalysts, the partial oxidation of methane was carried out over Pt/γ-Al2O3 and Pt/(Ce0.71Gd0.29)O2−x. Interestingly, the CH4 conversion for both materials was comparable. However, the amount of carbon deposited on Pt/(Ce0.71Gd0.29)O2−x was observed to be much less than on the alumina-supported Pt catalyst.