废弃SCR催化剂的循环再利用及表征分析研究

针对废弃SCR脱硝催化剂常规再利用处理后存在SO_2氧化率高的问题,提出了一种新型的废弃催化剂再利用新工艺,包括酸洗、还原酸浸和活性组分负载等步骤,以有效控制再利用催化剂的SO_2氧化率。实验考察了经不同步骤处理后所得催化剂的组分、脱硝效率和SO_2氧化率的变化情况,并对催化剂进行了深入的分析表征。结果表明,新鲜催化剂、废弃催化剂、常规再利用催化剂、新型再利用催化剂的脱硝效率和SO_2氧化率分别为99.0%和0.43%、77.0%和0.46%、94.2%和0.80%、99.3%和0.48%,采用本方法获得的再利用催化剂不仅脱硝效率完全恢复,而且SO_2氧化率得到了很好的控制。通过对催化剂的分析表征发现,采用常规再利用技术不能有效清除废弃催化剂表面的高聚态钒物种,而本方法则可以有效清理这类高聚态钒物种,并以高度分散的钒物种进行替代,从而有效控制再利用催化剂的SO_2氧化率。

Research on recycling and characterization analysis of the waste SCR catalyst

In the light of a high SO₂ oxidation ratio of the recycled waste SCR catalyst during conventional recycling denitrification, a novel recycling technique, including acid washing, acid leaching under reduction condition and active components loading, was proposed to control the SO₂ oxidation ratio of the recycled catalyst. The experiments were performed to determine the components, denitrification efficiency and SO₂ oxidation ratio of the catalysts obtained in different recycling runs, and the catalysts used were characterized. The results indicate that the denitrification efficiency and SO₂ oxidation ratio of the fresh catalyst, waste catalyst, conventional recycled catalyst and novel recycled catalyst are 99.0% and 0.43%, 77.0% and 0.46%, 94.2% and 0.80%, 99.3% and 0.48%, respectively. Through novel recycling method, both denitrification efficiency and SO₂ oxidation ratio of the recycled catalyst are well recovered. The characterization results suggest that the highly polymerized vanadium species on the surface of the waste catalyst could not be removed by using conventional recycling method, but the novel recycling method is effective for removing these vanadium species and replacing them with highly dispersed vanadium species, resulting in a reduction of SO₂ oxidation ratio of the recycled catalyst.