蜂窝状筛网催化剂上NH_3选择性催化还原NO的工艺特性

采用蜂窝状筛网催化剂进行NH3选择性催化还原NO的反应 ,考察了温度、空速、进料比及进料气、氧、水含量等因素对其催化性能的影响。结果表明 :进料气含量和进料比的增加均可提高NO的转化率 ;体积分数 2 %的氧便可封闭催化循环 ,显著提高NO转化率 ;当水体积分数在 2 %以内时 ,水的添加将导致NO转化率的降低。蜂窝状筛网催化剂与蜂窝状堇青石催化剂相比 ,具有优异的非稳态响应特性 ,反应可在较短的时间内进入稳态

Characteristics of Wire-Mesh-Honeycomb Catalyst for Selective Catalytic Reduction of NO with NH3

Wire-mesh-honeycomb catalyst not only has excellent mass transfer property of powder but also moderate pressure drop of ceramic honeycomb due to its high porous structure.It also has the following advantages:high thermal shock resistance,geometric flexibility,simplicity in catalyst recovery,excellent thermal response ,high mechanical strength,good axial dispersion and low cost.This paper investigated the selective catalytic reduction(SCR) of NO with NH 3 on wire-mesh-honeycomb catalyst.The effects of temperature,space velocity,concentration,feed ratio,oxygen and water on the catalytic properties of wire-mesh-honeycomb catalyst were investigated.The results showed that NO reduction was controlled by chemical kinetics and increased with increase in temperature when t <280 ℃.The maximum NO conversion reached a maximum at about 320 ℃.Ammonia oxidation began at t =340 ℃.When t >380 ℃,the reaction was fully controlled by ammonia oxidation.NO conversion increased with increase in feed concentration and n (NH 3)/ n (NO).NO reduction was seriously inhibited under a condition of oxygen deficiency.Oxygen with a volume fraction of 2% was sufficient for sustaining the reduction reaction.With water volume fraction below 2%,the addition of water at temperatures <340 ℃ lowered NO conversion,while the addition of water at higher temperatures enhanced reaction selectivity.With water volume fraction above 4%,the addition of water hardly affect the NO conversion.Wire-mesh-honeycomb catalyst has excellent unsteady state response than ceramic honeycomb catalyst.