NO reduction with ammonia employing Co/Pt supported on a mesoporous silica containing zirconium as a low temperature selective reduction catalyst

摘要

Selective catalytic reduction(SCR)of NO with ammonia in an excess of oxygen was carried out over cobalt-platinum impregnated on a zirconium containing mesoporous silica(Si/Zr molar ratio of 5)with a 12 wt.% of Cobalt and Co/Pt molar ratios of 10,20 and 30.These catalysts were compared with two catalysts containing 12 wt.% of Co and 1.5 wt.% of Ft,respectively.The presence of platinum improves the reducibility of Co(III)to Co(II)and at the same time the presence of cobalt ions impedes the reduction of Pt(II)to Pt(0).This gives rise to a synergetic effect,especially in the case of the catalyst with a Co/Pt molar ratio of 30,exhibiting a good performance in the SCR of NO by ammonia,even when water or SO_2 are added to the feed on stream,and maintaining high conversion and selectivity at moderately low temperatures(250 deg C).In fact,this catalyst maintains a conversion of 84% at 300 deg C in the presence of water during 24 h.