SCR脱硝催化剂再生技术试验研究

Regeneration technology of SCR catalysts: an experimental study

对选择性催化还原法(SCR)脱硝催化剂再生工艺进行研究。用X射线晶体衍射(XRD),X射线荧光光谱(XRF),X射线光电子能谱(XPS)和比表面积分析等方法对再生前、后的催化剂进行了表征;采用模拟烟气在自制脱硝反应装置上对催化剂再生效果进行了评价。研究发现:通过鼓泡或超声波辅助的稀H2SO4清洗可有效去除催化剂中的有毒物质并恢复比表面积,且鼓泡的综合效果更好;以乙醇胺为助溶剂,可根据所需钒的补充量配制不同浓度的偏钒酸铵水溶液,采用浸渍-干燥-煅烧工艺,可实现活性物质钒氧化物的补充,使催化剂的脱硝效率恢复至92%;用溶解性较好的硝酸铈代替偏钒酸铵,向失活催化剂中添加活性物质氧化铈,可拓宽脱硝反应的温度区间,并将催化剂的脱硝效率最高值提至90%。

Regeneration process of the SCR catalyst was investigated. Several methods such as the X-ray diffraction（ XRD）,X-ray fluorescence（ XRF）,X-ray photoelectron spectroscopy（ XPS） and specific surface area analysis were employed to characterize the catalysts before and after the regeneration. Moreover,the regeneration effect was also tested on a laboratory bench with simulated flue gas. The results show that,cleaning using aeration or ultrasonic assisted dilute sulfuric acid was proved to be effective in eliminating the poisons and recovering the specific surface area,and the aeration way performed better. With the aid of cosolvent ethanolamine,ammonium vanadate aqueous solutions with different concentrations could be obtained and used as precursors for active material replenishment.After drying and calcination,the catalysts were replenished with vanadium oxide,and the NO conversion ratio could reach up to 92%. Cerium nitrate was an alternative for ammonium vanadate because of its excellent solubility in water. After the impregnating-drying-calcining process,the catalyst was regenerated with cerium oxide,thus the temperature window was extended and the NO conversion ratio was enhanced to 90% at most.