Influence of the addition of H2 upon the behavior and properties of a Pd(2 wt.%)/γ-Al2O3 catalyst and a comparison with the case of the Pt-based catalyst

The influence of adding H2 in the feed during catalytic combustion of methane (CCM) on a Pd(2 wt.%)/γ-Al2O3 catalyst is studied. Various effects on the performances of the catalyst are observed, depending on the H2 concentration. Activation is observed at low H2 concentrations, but if too large concentrations of hydrogen are used (5 vol.% in this case), reduction of the surface of the palladium particles occurs and deactivation of the catalyst is therefore observed. A mechanistic interpretation is proposed, which explains the experimental observations. A comparison is also made with the characteristics of a Pt(2 wt.%)/γ-Al2O3 catalyst. Both catalysts display different behavior towards the presence of H2, which probably reflects different reaction pathways for CCM.