Combined Effect of H2O and SO2 on V2O5/AC Catalysts for NO Reduction with Ammonia at Lower Temperatures

Abstract Combined effect of H 2 O and SO 2 on V 2 O 5 /AC the activity of catalyst for selective catalytic reduction (SCR) of NO with NH 3 at lower temperatures was studied. In the absence of SO 2 , H 2 O inhibits the catalytic activity, which may be attributed to competitive adsorption of H 2 O and reactants (NO and/or NH 3 ). Although SO 2 promotes the SCR activity of the V 2 O 5 /AC catalyst in the absence of H 2 O, it speeds the deactivation of the catalyst in the presence of H 2 O. The dual effect of SO 2 is attributed to the SO 4 2− formed on the catalyst surface, which stays as ammonium-sulfate salts on the catalyst surface. In the absence of H 2 O, a small amount of ammonium-sulfate salts deposits on the surface of the catalyst, which promote the SCR activity; in the presence of H 2 O, however, the deposition rate of ammonium-sulfate salts is much greater, which results in blocking of the catalyst pores and deactivates the catalyst. Decreasing V 2 O 5 loading decreases the deactivation rate of the catalyst. The catalyst can be used stably at a space velocity of 9000 h −1 and temperature of 250 °C.

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