水对V2O5/AC催化剂低温还原NO的影响

 研究了烟气中的水对新型V2O5／AC催化剂选择催化还原NO的影响．结果表明，水通过与反应物（如NO和NH3）的竞争吸附而在一定程度上降低了催化剂的活性．在SO2共存下，水的存在导致硫酸铵盐在催化剂表面的过量沉积，造成催化剂孔道堵塞，比表面积减小，从而使催化剂失活．较高的反应温度（如553K）和／或低空速有利于催化剂的活性和稳定性．脱除活性焦载体中的矿物质可在一定程度上减缓催化剂失活的速率，但不能完全抑制水对V2O5／AC催化剂的毒化作用．

Effect of Water on V2O5/AC Catalyst for NO Reduction byNH3 at Lower Temperature

Effect of water on 1%V 2O 5/AC catalyst for selective catalytic reduction (SCR) of NO with NH 3 was studied. The activated coke (AC) was prepared from a commercial coal derived semi coke through steam activation. After AC was oxidized by concentrated HNO 3, the catalysts were prepared by equivalent volume impregnation of AC with aqueous solution of ammonium metavanadate in oxalic acid. The results showed that the water inhibits SCR reaction and deactivates V 2O 5/AC catalyst below 523 K. The inhibition is due to the competitive adsorption of water and reactants (NH 3 and/or NO) on the catalyst surface. The deactivation is caused by deposition of ammonium sulfate salts on the catalyst surface in the presence of SO 2, reducing the surface area and blocking the pores of the catalyst. The deactivation of the catalyst is lessened or even prevented at high temperature and/or low space velocity (553 K, 90?000 h -1 or 523 K, 9?000 h -1 ). Removal of the minerals in AC can prolong the catalyst lifetime. However, demineralization can not completely prevent the catalyst from deactivation by water.