Catalytic Post-Treatment of Automotive Exhaust Gas from Natural Gas Combustion Engines: Potential Interest of Perovskite Materials
This study reports an investigation of the surface properties of Pd-modified perovskite catalysts for NO x removal from Natural Gas engines. H2 production from reforming and water-gas-shift reactions can be profitably used for the reduction of NO x . Particular attention has been paid to the nature of interactions between Pd and LaCoO3 according to in situ reductive thermal treatments. The catalytic properties have been investigated by temperature-programmed NO desorption and temperature-programmed NO/H2 reaction. Different experiments performed on partially and extensively reduced catalysts lead to changes in surface reactivity. Interestingly, beneficial interactions with a significant selectivity enhancement to the production of nitrogen is observed on pre-reduced Pd/LaCoO3 under smooth conditions at 250 °C particularly in the presence of oxygen. More extensive reduction at 450 °C leads to the loss of the structural properties of LaCoO3 accompanied with partial segregation of CoO x and La2O3. Such structural changes lead to a detrimental effect on the catalytic performances.
KeywordsDeNOx catalysis Palladium LaCoO3 NO/H2 reaction
We thank the Institute of Research in Industrial Environment supported by Region Nord-Pas-de-Calais and the Ademe for a grant (Y. Renème).