Experimental study on the selective catalytic reduction of NO with C3H6 over Co/Fe/Al2O3/cordierite catalysts
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摘要: 采用溶胶凝胶法和浸渍法制备了负载于蜂窝陶瓷上的Co/Fe/Al2O3/cordierite催化剂,在陶瓷管流动反应器上对其催化C3H6选择性还原NO的性能进行了测试。结果表明,该催化剂表现出最优脱硝性能,在模拟烟气条件下,当反应温度为550 ℃时可实现97%的脱硝效率。Co的引入可显著增强Fe/Al2O3/cordierite催化剂抗SO2和H2O的能力。在模拟烟气中同时引入0.02% SO2和3% H2O后,1.5Co/Fe/Al2O3/cordierite的脱硝性能受影响甚微,当反应温度高于500 ℃时1.5Co/Fe/Al2O3/cordierite催化C3H6还原NO的效率均可达到90%以上;相比之下,未经Co修饰的催化剂Fe/Al2O3/cordierite脱硝性能受到了严重的抑制,在整个反应温度区间(200-700 ℃)内,其催化C3H6还原NO的效率最高不足50%。XRD和SEM表征结果表明,经过适量的Co修饰后的1.5Co/Fe/Al2O3/cordierite表面变得更疏松,且形成了以钴铁和钴铝双金属氧化物为主要成分的球状晶粒。H2-TPR结果表明,相比于Fe/Al2O3/cordierite,1.5Co/Fe/Al2O3/cordierite有更好的低温还原性能。Py-FTIR结果表明,Co的引入可使催化剂表面的Lewis酸明显增加,且生成了Brønsted酸。N2吸附-脱附表征结果表明,Co可增大催化剂的比表面积。
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关键词:
- 选择性催化还原 /
- Co/Fe/Al2O3/cordierite催化剂 /
- NO /
- 丙烯
Abstract: The Co/Fe/Al2O3/cordierite catalysts with different Co loadings were prepared by sol-gel and impregnation methods, and their performance in the selective catalytic reduction of NO with C3H6 over catalytic were experimentally studied in a ceramic tubular reactor. The results indicated that 1.5Co/Fe/Al2O3/cordierite showed the highest C3H6-SCR activity with 97% NO reduction in the simulated flue gas at 550 ℃. Cobalt was able to effectively improve the ability of Fe/Al2O3/cordierite catalysts to resist SO2 and H2O in flue gas. When 0.02% SO2 and 3% water vapor were added to the simulated flue gas, the NO reduction efficiency of 1.5Co/Fe/Al2O3/cordierite was almost unaffected, the NO reduction by 1.5Co/Fe/Al2O3/cordierite with C3H6 all surpassed 90%. In contrast, the catalytic activity of Fe/Al2O3/cordierite without cobalt modification was seriously suppressed by SO2 and H2O, the highest NO reduction efficiency of Fe/Al2O3/cordierite was less than 50% within the entire reaction temperature range (200-700 ℃).XRD and SEM results showed that the surface of 1.5Co/Fe/Al2O3/cordierite after the modification by cobalt became loose, and formed by the cobalt iron and cobalt aluminum metal oxide-based spherical grains.H2-TPR results showed that 1.5Co/Fe/Al2O3/cordierite had better low temperature reduction performance than Fe/Al2O3/cordierite. Py-FTIR results confirmed that Co can dramatically increased the Lewis acid and produced Brønsted acid on the catalyst surface. N2 adsorption/desorption characterization results proved that Co can increase the specific surface area of the catalyst.-
Key words:
- selective catalytic reduction of NO /
- Co/Fe/Al2O3/cordierite catalyst /
- NO /
- C3H6
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图 3 SO2和水蒸气对1.5Co/Fe/Al2O3/cordierite催化剂催化活性的影响
Figure 3 Effect of SO2 and water vapor on the catalytic activity of 1.5Co/Fe/Al2O3/cordierite on NO conversion
(a): NO conversion vs temperature with/without 0.02% SO2 and 3% H2O; (b): effect of 0.02% SO2; (c): 2.5% H2O on NO conversion vs reaction time (flow rate=1.5 L/min, NO=0.05%, C3H6=0.3%, O2=1%, N2 balanced, 550℃)
表 1 三组典型的催化剂中酸性位的含量
Table 1 Acid amount of the three typical catalyst samples
Sample 40 ℃ 170 ℃ 300 ℃ B/
(μmol·g-1)L/
(μmol·g-1)B/
(μmol·g-1)L/
(μmol·g-1)B/
(μmol·g-1)L/
(μmol·g-1)Fe/Al2O3/cordierite[19] 0 6 0 4.18 0 1.9 1.5Co/Fe/Al2O3/cordierite 16.4 686 11.2 427 0 75 4.3Co/Fe/Al2O3/cordierite 16.2 343 15 239 0 85 表 2 不同负载量催化剂的微孔隙特性
Table 2 Textural properties of the catalysts with different Co/Fe loadings
Catalyst ABET/(m2·g-1) vp/(cm3·g-1) dp/nm Fe /Al2O3/cordierite [38] 19 0.039 6.54 0.5Co/Fe/Al2O3/cordierite 18 0.038 8.51 1.5Co/Fe/20Al2O3/cordierite 23 0.039 6.90 4.3Co/Fe/20Al2O3/cordierite 24 0.041 7.13 -
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