Simple physical mixing of zeolite prevents sulfur deactivation of vanadia catalysts for NOx removal

NOx abatement has been an indispensable part of environmental catalysis for decades. Selective catalytic reduction with ammonia using V2O5/TiO2 is an important technology for removing NOx emitted from industrial facilities. However, it has been a huge challenge for the catalyst to operate at low temperatures, because ammonium bisulfate (ABS) forms and causes deactivation by blocking the pores of the catalyst. Here, we report that physically mixed H-Y zeolite effectively protects vanadium active sites by trapping ABS in micropores. The mixed catalysts operate stably at a low temperature of 220 degrees C, which is below the dew point of ABS. The sulfur resistance of this system is fully maintained during repeated aging/regeneration cycles because the trapped ABS easily decomposes at 350 degrees C. Further investigations reveal that the pore structure and the amount of framework Al determined the trapping ability of various zeolites.

Automated summary

This study demonstrates that physically mixed H-Y zeolite can protect vanadium active sites effectively by trapping ABS in micropores, enabling the catalyst to operate stably at low temperatures and maintaining sulfur resistance during repeated aging/regeneration cycles. The pore structure and framework Al content of different zeolites play a crucial role in determining the trapping ability.