Tailoring the metal-perovskite interface for promotional steering of the catalytic NO reduction by CO in the presence of H₂O on Pd-Lanthanum iron manganite composites

Abstract

We steer the catalytic performance and morphology of Pd – lanthanum iron manganite (LFM) perovskite interfaces towards optimum NO+CO reactivity in presence of water by following different preparation approaches. Strong CO adsorption for samples without Pd-perovskite interface acts as an inhibitor for adsorption/dissociation of NO, while samples with an extended interface, additionally aided by H₂O, show reduced CO poisoning. The optimized use of lattice oxygen for CO oxidation at the phase boundary and its replenishment from NO dissociation allows for the formation of more poisoning-resistant active sites for NO activation. Reaction of species from H₂O dissociation with adsorbed CO assists further surface clean off. Enhanced NO reduction activity on the “de-poisoned” interface leads to a pronounced increase in N₂ selectivity. Preferred production of NH₃ at low NO and high CO and H₂O concentration indicates that water gas shift intermediates are linked to increased surface hydrogen activity and increased NH₃ formation.