燃煤电厂SCR催化剂的失活及再生实验研究

对某燃煤电站脱硝系统已运行24000 h的SCR催化剂进行活性测试,利用XRD、BET、XRF、FT-IR和XPS等表征手段分析发现,催化剂出现微、中孔堵塞及活性物质氧化等问题,导致催化剂失活。采用水洗和酸洗方法清除催化剂孔道中的堵塞物,发现水洗能还原部分V物质而酸洗能恢复催化剂表面的活性位并均匀负载具有提高活性位酸性作用的硫物种。对水洗后的催化剂进行SO_2硫化处理,发现相比酸洗Br■nsted和Lewis酸性位强度提高的同时Lewis酸性位密度也提高。再生处理后,酸洗在250℃以上活性恢复到新鲜催化剂水平,450℃硫化催化剂活性在380℃达到新鲜催化剂活性的104.6%。

Deactivation and regeneration of commercial SCR catalysts used in coal fired power plant

The activity of SCR catalyst used in a coal-fired power plant for 24000 h was tested. With the help of XRD, BET, XRF, FT-IR and XPS, it is found that the catalyst has some problems such as micropore and mesopore plugging and the oxidation of active substances, which leads to the deactivation of the catalyst. Water washing and H₂SO₄ washing were used to remove plugs in the pores of the catalyst. The result shows that water washing can resume part of vanadium species and H₂SO₄ washing can renew the active sites on the surface of catalyst and uniformly load the sulfur species which can increase the acidity of active site. The SO₂ sulphation treatment was performed on the catalyst after water washing. It is indicated that the Brønsted acid and the Lewis acid sites have higher strength and the Lewis acid has higher density than that by H₂SO₄ washing. After the regeneration treatment, H₂SO₄ washed catalyst activity is restored to the level of fresh catalyst above 250 ℃. And the activity of SO₂ sulphation catalyst at 450 ℃ reaches 104.6% of the fresh catalyst activity at 380 ℃.