SCR脱硝催化剂硫酸钙失活及再生试验

Experimental study on SCR catalyst:deactivation by calcium sulfate and catalyst regeneration

对工业用某脱硝催化剂样品进行了模拟硫酸钙(Ca SO4)失活以及失活后再生的试验研究。试验在不同的再生药剂及再生条件下,用X射线衍射、X射线荧光光谱和比表面积分析等方法对再生前后的催化剂进行了表征,在实验室模拟烟气条件下对催化剂再生效果进行了分析。研究发现:催化剂微孔被Ca SO4堵塞或覆盖后,脱硝效率明显下降;酸X清洗能够清除部分钙化合物,但无法清洗Ca SO4;螯合剂Y与氨水配制的溶液可有效去除Ca SO4,同时恢复比表面积,且碱性条件下清洗效果更好;经过螯合剂Y溶液清洗后的催化剂活性物质V有所下降,这会降低催化剂的脱硝效率,利用钒盐负载液NH4VO3浸渍后干燥焙烧,可实现对催化剂活性物质钒氧化物的补充,并将催化剂的脱硝效率恢复至新催化剂水平。

For a denitration catalyst used for industry, experimental study on deactivation of calcium sulfate and regeneration was carried out. Different regeneration solutions and conditions were investigated. Several analysis, like the X-ray diffraction （XRD）, X-ray fluorescence （XRF） and specific surface area analysis were employed to characterize the catalysts before and after the regneration, and the catalytic activities were also tested on a laboratory bench with simulated flue gas. The results show that, after the catalysts＇ inside micro pores were blocked or masked by calcium sulfate, the NO conversion ratio decreased sharply. A kind of acid which was called X in the paper could remove part of the calcium compounds, however, it had no effect on calcium sulfate. A kind of chelating agent which was called Y, blending with aqueous ammonia, acted well on removing calcium sulfate and recovering the specific surface area. The chelating agent Y worked better in basic solutions. The content of vanadium oxides in the catalysts decreased when washing with chelating agent Y, therefore reduced the NO conversion ratio.The ammonium vanadate aqueous solution was employed to replenish the vanadium oxides. After drying and calcination, the NO cOnversion rate was recovered as high as that of the fresh catalyst.