Experimental study on selective catalytic reduction of NO with propene over iron based catalysts supported on aluminum pillared clays
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摘要: 采用浸渍法制备了负载于铝柱撑黏土的铁基催化剂(Fe/Al-PILC),在固定床反应器上测试其催化C3H6选择性还原NO的性能。通过N2吸附-脱附、X射线衍射(XRD)、H2的程序升温还原(H2-TPR)、紫外可见光谱(Uv-vis)、吡啶吸附红外光谱(Py-FTIR)等手段对催化剂的物理化学性质进行表征。结果表明,9Fe/Al-PILC在400-550 ℃能够还原98%以上的NO,而且SO2和水蒸气对其催化性能的影响很小。XRD、N2吸附-脱附表征结果表明,Fe/Al-PILC催化剂中铁氧化物高度分散在载体表面,催化剂有较大的比表面积和孔容。H2-TPR结果表明,催化剂的活性主要由Fe2O3物相的还原性能决定。Uv-vis结果表明,催化剂的活性与铁氧低聚物种FexOy呈正相关性。Py-FTIR结果表明,催化剂表面同时存在Lewis酸和Brønsted酸,L酸性位是NO和C3H6反应的主要催化活性中心。Abstract: Iron based catalysts supported on aluminum pillared clays (Fe/Al-PILC) was prepared by impregnation method and the selective catalytic reduction of NO with propene by the Fe/Al-PILC catalysts was investigated in a fixed bed reactor. The physical and chemical properties of the catalysts were characterized by N2 adsorption/desorption, XRD, H2-TPR, Uv-vis, Py-FTIR, etc. Results showed that 9% Fe/Al-PILC reduced more than 98% of NO at 400-550℃. SO2 and water vapor slightly influenced the catalytic activity of the catalysts. XRD and N2 adsorption/desorption characterization results revealed that the iron oxides in the catalyst were highly dispersed on the surface of the carrier, and the catalyst has a large specific surface area and pore volume. H2-TPR results indicated that the activity of the catalysts was mainly determined by the reduction performance of Fe2O3 phase. Uv-vis results showed that the activity of the catalysts was positively correlated with the iron oxide oligomer FexOy. Py-FTIR results indicated that both Lewis acid and Brønsted acid were formed on the catalyst surface and the Lewis acid sites were the main catalytic activity center of NO and C3H6 reaction.
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Key words:
- NO /
- selective catalytic reduction /
- Al-PILC /
- iron /
- C3H6
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图 1 不同催化剂取得的NO和C3H6转化率及N2选择性随反应温度的变化
Figure 1 NO conversion to N2(a), C3H6 conversion (b), N2 selectivity(c) over Fe/Al-PILC with different iron loading
reaction conditions: φNO=0.05%, φC3H6=0.3%, φO2 =1%, He=balance and GHSV=15 000 h-1
—■—4Fe/Al-PILC; —●—6Fe/Al-PILC; —▲—9Fe/Al-PILC; —▼—13Fe/Al-PILC; —◆—Al-PILC表 1 不同催化剂的物理特性
Table 1 Physical property of different catalysts
Catalyst Fe w/ (mg·g-1) ABET /(m2·g-1) Pore volume v/(cm3·g-1) Pore diameter d/nm Al-PILC 188 0.328 5.61 4Fe/Al-PILC 40.19 164 0.258 5.52 9Fe/Al-PILC 92.54 186 0.264 4.91 13Fe/Al-PILC 131.19 65 0.097 4.84 表 2 不同催化剂的B酸和L酸含量
Table 2 Brønsted and Lewis acid content of different catalysts
Sample 170 ℃ desorption /(mmol·g-1) 300 ℃ desorption /(mmol·g-1) B L B L Al-PILC 0.005 12 0.051 29 0 0.035 80 4Fe/Al-PILC 0.003 97 0.025 80 0 0.011 40 9Fe/Al-PILC 0.006 91 0.046 95 0 0.034 43 -
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