SO_2 ssorption on fresh and aged SO_x traps

摘要

This study has bn important impact on gasoline engine-pollution control working under lean conditions.While NO_x trap systems can remove NO_x under an oxidative atmosphere,they are poisoned by SO_x present in the ezhaust agses.In order to protect NO_x traps,an upsteam SO_x trap has to be used.SO_2 adsorption was studied in teh presence of water and oxygen.Model and commercial catalysts were sested between 300 and 700 deg C In order to assign the TPD peaks,the decomposition of commercial suhphates wea studied versus the temperature.Assorption capacity in not sensitive to oxygen and SO_2 concetrations but is strongly related to barium content.Cerium content is not a key parameter for SO_2 assorpation capacity in the presence of oxygen.XPS analysis allowed us to differentiate between all the species formed durign the assorption process.When the catalysts are aged ,specific surface area decreases as well as adsorption capacity.