SO2对稀土精矿催化剂NH3-SCR脱硝催化性能的影响

doi:10.11949/0438-1157.20190641

摘要/Abstract

摘要：

抗硫性能是评价脱硝过程中催化剂性能的关键指标，研究SO₂对催化剂理化特性的影响对催化剂脱硝应用具有重要意义。通过焙烧处理白云鄂博稀土精矿得到稀土精矿催化剂，利用催化剂抗硫性能实验台，结合SEM、BET、XRD和FT-IR，分析了O₂、NH₃、NO气氛下SO₂在催化剂表面的吸附及不同SO₂浓度对催化剂催化脱硝性能的影响。结果表明， SO₂对稀土精矿催化剂脱硝性能有显著的促进作用，300℃时，NO转化率从28%提高至50%，350℃时，NO转化率从42%提高至75%； SEM、BET和XRD结果表明催化剂抗硫性能测试前后的物理结构和化学组成基本保持不变，稀土精矿催化剂具有较好的抗硫性能；FT-IR结果证实SO₂的吸附使稀土精矿催化剂表面B酸性位点增多，催化剂对NH₃的吸附能力增强，因此有利于提高催化剂活性。研究结果可为白云鄂博稀土精矿催化剂NH₃-SCR脱硝应用过程中抗硫性能提供有价值的基础数据参考。

关键词: 稀土精矿催化剂, SO₂, 催化剂活性, 抗硫性能, NH₃吸附

Abstract:

Sulfur resistance is a key indicator for evaluating catalyst performance during denitration. It is important to study the effect of SO₂ on the physicochemical properties of catalysts. The rare earth concentrate catalyst was obtained by roasting the Bayan Obo rare earth concentrate. Using the sulfur resistance test bed of the catalyst and combining scanning electron microscope (SEM), Brunner Emmett Teller(BET), X-ray diffraction (XRD) and in situ Fourier transform infrared spectroscopy (FT-IR), the adsorption of SO₂ on the catalyst surface under the atmosphere of O₂, NH₃ and NO, as well as the influence of different SO₂ concentrations on catalytic denitrification were analyzed. The results show that SO₂ can significantly promote the denitrification performance of rare earth concentrate catalysts. The NO conversion rate increased from 28% to 50% at 300℃ and increased from 42% to 75% at 350℃. SEM, BET and XRD results illustrated that the surface structure and chemical composition of the catalyst remain unchanged before and after denitrification. The rare earth concentrate had good sulfur resistance. The FT-IR results verified that the adsorption of SO₂ increased B acid sites on the surface of the rare earth concentrate catalyst. The adsorption capacity of the catalyst for NH₃was enhanced, contributing to increase catalyst activity. The results can provide valuable basic data reference for the anti-sulfur performance of the Bayan Obo rare earth concentrate catalyst NH₃-SCR denitrification application process.

Key words: rare earth concentrate catalyst, SO₂, catalyst activity, sulfur resistance, NH₃adsorption

中图分类号:

TQ 028.8

焦坤灵, 赵阳国, 武文斐, 王振峰, 龚志军. SO₂对稀土精矿催化剂NH₃-SCR脱硝催化性能的影响[J]. 化工学报, 2019, 70(12): 4645-4653.

Kunling JIAO, Yangguo ZHAO, Wenfei WU, Zhenfeng WANG, Zhijun GONG. Effect of SO₂ on catalytic performance of rare earth concentrate catalyst for NH₃-SCR denitrification[J]. CIESC Journal, 2019, 70(12): 4645-4653.

图/表 13

表1 稀土精矿催化剂XRF分析结果

Table 1 XRF analysis of rare earth concentrate catalysts

元素	含量/%
CeO₂	28.9
CaO	9.3
La₂O₃	17.9
Fe₂O₃	3.7
Nd₂O₃	9.6
F	6.2
Al₂O₃	4.9
P₂O₅	10.2
Pr₂O₃	2.8
SiO₂	2.1
其他	4.4

图1 SCR抗硫性能测试实验装置1—标准气瓶；2—减压阀；3—混气箱；4—石英管；5—管式炉；6—石英棉；7—催化剂；8—烟气分析仪

Fig.1 SCR sulfur resistance testing device

表2 催化剂 SCR 抗硫性能测试的反应条件

Table 2 Reaction conditions for testing sulfur resistance of catalyst SCR

φ_NO	$φ N H 3$	$φ O 2$	$φ S O 2$	催化剂填装量/g	气体总流量/(ml/min)	恒温时间/min	反应温度/℃
500×10^-6	500×10^-6	3×10^-2	100×10^-6~500×10^-6	0.2	100	180	300/350

表2 催化剂 SCR 抗硫性能测试的反应条件

Table 2 Reaction conditions for testing sulfur resistance of catalyst SCR

φ_NO	$φ N H 3$	$φ O 2$	$φ S O 2$	催化剂填装量/g	气体总流量/(ml/min)	恒温时间/min	反应温度/℃
500×10^-6	500×10^-6	3×10^-2	100×10^-6~500×10^-6	0.2	100	180	300/350

图2 不同温度下稀土精矿催化剂脱硝效率

Fig.2 Denitrification efficiency of rare earth concentrate catalyst at different temperatures

图3 O2含量对催化剂吸附SO2的影响

Fig.3 Effect of O2 content on SO2 adsorption by catalyst

图4 有O2条件下NH3对SO2浓度的影响

Fig.4 Effect of NH3 on SO2 concentration under condition of O2

图5 有O2条件下NO对SO2浓度的影响

Fig.5 Effect of NO on SO2 concentration under condition of O2

图6 不同浓度SO2对稀土精矿催化剂催化活性的影响

Fig.6 Effect of SO2 concentration on catalytic activity of rare earth concentrate catalyst

图7 350℃时催化剂抗硫性能测试中SO2浓度变化

Fig.7 Changes of SO2 concentration in test of sulfur resistance of catalyst at 350℃

图8 稀土精矿催化剂抗硫测试前后SEM图

Fig.8 SEM images of rare earth concentrate catalysts before and after sulfur resistance test

表3 抗硫测试前后催化剂BET分析结果

Table 3 BET analysis results of catalysts before and after sulfur resistance test

样品	比表面积/(m²/g)	孔体积/(cm³/g）	平均孔径/nm
测试前催化剂	47.228	0.037	3.049
测试后催化剂	46.886	0.031	3.068

图9 抗硫测试前后稀土精矿催化剂的XRD谱图

Fig.9 XRD patterns of rare earth concentrate catalyst before and after sulfur resistance test

图10 催化剂表面SO2吸附对NH3吸附影响的原位红外图谱

Fig.10 In-situ infrared spectra of effect of SO2 adsorption on NH3 adsorption on catalyst surface

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SO₂对稀土精矿催化剂NH₃-SCR脱硝催化性能的影响

Effect of SO₂ on catalytic performance of rare earth concentrate catalyst for NH₃-SCR denitrification

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