Enhanced dual resistance to alkali metal and phosphate poisoning: Mo modifying vanadium-titanate nanotubes SCR catalyst

Abstract

The presence of alkali metal and phosphate species significantly deactivate deNOx catalysts. In this work, molybdenum was applied as a key additive for Vanadium-Titanate nanotubes (V-TNTs) catalysts to alleviate the dual poisoning by potassium and phosphate. The addition of Mo improved the resistance of V-TNTs from 70% to >95% in the temperature region of 300–450 °C. The introduction of Mo helped to preserve the redox properties and Brønsted acidic sites of the poisoned catalysts by potassium and phosphate. This behavior mainly resulted from the interaction of Mo with phosphate, followed by the regeneration of active and acidic sites. Moreover, in-situ DRIFTs spectra showed that Mo not only enhanced the NH3 and NO adsorption but also contributed to the activation of adsorbed NO species, making them react with NH3 more easily over Mo-contained catalysts then directly influencing the selective catalytic reduction (SCR) activity as well as dual poisoning resistance. Therefore, supporting materials with abundant acidic sites and appropriate additives can significantly alleviate the dual poisoning by alkali metals and phosphate.