Effect of support morphology on the sulfur tolerance of V2O5/Al2O3 catalyst for the reduction of NO by NH3

Abstract

The morphological effect of Al2O3 on the deactivation of V2O5/Al2O3 catalyst by SO2 for the removal of NO with NH3 has been examined to identify the promise of alumina as a support for commercial SCR catalysts. A test program for accelerated batch-type deactivation at 400 degreesC and accelerated continuous deactivation at 250 degreesC was developed for V2O5/Al2O3 catalysts containing distinctive pore size distributions of Al2O3. The pore size of the catalyst was critical for the deactivation of V2O5/Al2O3 catalyst along with the surface area. A catalyst containing a high surface area with large mean pores might be an ideal catalyst exhibiting a prolonged catalyst lifetime prolonged for the SCR process because of the SO2. The content of vanadia on the surface Of Al2O3 is also important in elucidating the role of the morphology of the support in the deactivation of the catalyst. For the batch deactivation test of the catalyst at 400 degreesC, a high vanadia content of about 20 wt % is required on the catalyst surface, whereas a low content of 7 wt % is appropriate for continuous deactivation at 250 degreesC. V2O5/Al2O3 catalysts at 250 degreesC are easily deactivated by pore filling and/or pore plugging resulting from the formation of deactivating agents such as NH4HSO4 and (NH4)(2)SO4. At 400 degreesC, Al-2(SO4)(3) and AlNH4(SO4)(2) are generated and slowly plug the pores in the catalyst surface, so that the deactivation is hardly distinctive from that occurring at 250 degreesC.