Positive effects of K+ in hybrid CoMn-K and Pd/Ba/Al2O3 catalysts for NOx storage and reduction

Abstract

CoMn-K was mechanically mixed with a Pd/Ba/Al2O3 catalyst to enhance its NOx storage and reduction properties. The Pd/Ba/Al2O3 and CoMn-K mixture showed a synergetic effect with respect to NOx storage capacity and improved NOx reduction ability. The addition of K+ ions promoted the catalytic performance by increasing NO oxidation activity and therefore NOx storage via the creation of active surface oxygen species on the catalysts. The stored NOx reduction by H2 was also improved, being ascribed to the fact that Pd was mainly present as Pd0 due to the electronic interactions between Pd and K+ ions. NOx conversions and N2 selectivity at low temperatures (80–200 °C) could be further enhanced by assistance of non-thermal plasma in rich phase.