A system with two catalyst beds instead of one single metal catalyst bed is proposed for catalytic partial oxidation of methane (CPOM) to synthesis gas. In this dual catalyst bed system, an irreducible stable oxide, such as yttrium-stabilized zirconia (YSZ), is used in the first catalyst bed to obtain selective oxidation to syngas with significant highly exothermic deep oxidation occurring as well. This feature results in milder temperature profiles in the reactor because less heat is liberated compared to initial deep oxidation as, e.g. on metal catalysts. More importantly, all oxygen is completely consumed in the oxide catalyst bed. The second bed comprises a metal catalyst, e.g. Co-based, for reforming methane with H2O and CO2 exclusively. In this way the catalysts are exposed to less extreme temperatures and, exposure of metallic catalysts to oxygen at high temperatures is prevented. Therefore catalyst deactivation via evaporation of precious metal oxides is circumvented. Finally, synthesis gas with an equilibrium composition (almost 100% CO and H2 yields) is produced.
Zhu, J. J., Mujeebur Rahuman, M. S. M., van Ommen, J. G., & Lefferts, L. (2004). Dual catalyst bed concept for catalytic partial oxidation of methane to synthesis gas. Applied catalysis A: general, 259, 95-100. https://doi.org/10.1016/j.apcata.2003.09.022