Studies on the regeneration of sulfur-poisoned NOX storage and reduction catalysts, including a Ba composite oxide

The analysis of sulfur deterioration and regeneration of a NOX storage and reduction (NSR) catalyst containing Ba as the storage material and TiO2 as the support was conducted. It was found that the inhibition of sulfur re-adsorption during the sulfur desorption procedure under a rich atmosphere is important for improving sulfur desorption from a sulfur poisoned NSR catalyst, and that the combination of a Ba compound and a TiO2 support is effective for the inhibition of sulfur poisoning under both lean and rich conditions. On the basis of these results, a highly dispersed Ba-Ti composite oxide catalyst was prepared using a Ba-Ti complex precursor in order to realize the nm-scale distribution of Ba and Ti. Furthermore, it was concluded that the principal factor contributing to the high performance of the Ba-Ti catalyst in terms of the sulfur desorption rate was its ability to inhibit repetitive adsorption during rich treatment for sulfur desorption.

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► Inhibition of sulfur re-adsorption under a rich condition improves NSR catalyst.
► Combination of Ba and Ti is effective for the inhibition of rich sulfur poisoning.
► The Ba-Ti composite oxide is more effective for a prevention of sulfur deactivation.