NOx reduction against sulfur poisoning by using Ce-modified Cu-SAPO-34 catalysts

Abstract

The problem of sulfur poisoning limits the application of Cu-SAPO-34 catalysts in the selective catalytic reduction of NO_x by an ammonia (NH₃-SCR) reaction eliminating NO_x emissions from diesel vehicles. In this work, NO_x reduction against sulfur poisoning was demonstrated by using Ce-modified Cu-SAPO-34 catalysts. The catalyst modified with small amounts (0.5 wt%) of Ce showed a remarkable sulfur tolerance during the NH₃-SCR of NO_x. The SCR performance of the sulfur-poisoned catalysts was significantly improved because Ce played a positive role in reducing the sulfate species deposited on the catalysts. Because of the enhanced binding of the Cu²⁺ ions to the framework of SAPO-34, the Cu-SAPO-34 catalyst incorporating 0.5 wt% of Ce could maintain more active Cu²⁺ after sulfur poisoning. This work facilitates the way forward for the development of highly efficient catalysts for NO_x reduction against sulfur poisoning.