CO Oxidation by and Reversible SO2 Deactivation of a Pd-Doped Perovskite Catalyst

The introduction of small amounts of Pd (ca. 5 at.%) on the B-site of the perovskite BaCeO3 results in a catalyst with good low temperature activity for CO oxidation, despite its low surface area. The labilization of lattice oxygen, caused by the presence of vacancies accompanying Pd(II) substitution for Ce(IV), leads to a reaction rate which is not CO-inhibited at high P(CO). The catalyst is partially deactivated in the presence of low levels (e.g., 20 ppm) of SO2, but the perovskite structure is not affected. The CO oxidation activity recovers spontaneously when SO2 is removed, with a rate law that depends on the redox stoichiometry of the feed.