Partial oxidation of methane on Ni and Pd catalysts: Influence of active phase and CeO2 modification

Ni/Al2O3, Pd/Al2O3, Ni/CeO2/Al2O3 and Pd/CeO2/Al2O3 catalysts were synthesized in order to investigate the influence of the active phase on the partial oxidation of methane (POM) and the effect of CeO2 on the catalytic properties of these systems. The catalysts were characterized by XRD, XRF, BET, XPS, H2-TPR and catalytic activity was evaluated by TPSR experiments and catalytic activity tests over 24 h on stream. The results indicated that over Ni catalysts the reaction occurs in two distinct steps: the total combustion of CH4 followed by reforming with H2O and CO2. Over Pd catalysts, the reaction follows a direct mechanism, with simultaneous formation of H2, CO, CO2 and H2O. Regarding CeO2 effect, the results indicated it improved the CH4 conversion, CO and H2 selectivity and catalytic activity and the resistance to deactivation.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (158 K)Download as PowerPoint slideHighlights► CeO2 improved the CH4 conversion, CO and H2 selectivity and the resistance to deactivation of the catalysts. ► CeO2 effect is attributed to the higher oxygen exchange capacity of the support. ► Over Pd/CeO2/Al2O3 catalysts, the reaction follows a direct mechanism. ► Over Ni/CeO2/Al2O3 POM occurs in two distinct steps: combustion followed by reforming.