酸性质对磷钨酸改性CeO<sub>2</sub>上NH<sub>3</sub>选择性催化还原NO性能影响

段言康; 宋忠贤; 张秋林; 刘启宪; 张金辉; 张腾飞; 孙二波

酸性质对磷钨酸改性CeO₂上NH₃选择性催化还原NO性能影响

1.
昆明理工大学环境科学与工程学院, 云南昆明 650500
2.
中石化集团, 河南洛阳 471000

基金项目:

国家自然科学基金 U1137603

详细信息

中图分类号: O643
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- 被引次数: 0
出版历程
- 收稿日期: 2016-04-15
- 修回日期: 2016-07-10
- 网络出版日期: 2021-01-23
- 刊出日期: 2016-10-10

Effect of acid property on selective catalytic reduction of NO with ammonia over photungstic acid modified CeO₂ catalyst

1.
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
2.
Sinope Group, Luoyang 471000, China

More Information

Corresponding author: Tel: 13668788376, E-mail: qiulinzhang_kmust@163.com

摘要

摘要: 分别制备了磷钨酸、磷酸、偏钨酸铵及磷酸+偏钨酸铵改性的CeO₂催化剂，用于NO的NH₃选择性催化还原反应（NH₃-SCR），对酸改性的作用进行了研究。结果表明，不同酸改性后的CeO₂催化剂均含有弱酸和中强酸位，但酸量差别明显，依次为：磷钨酸/CeO₂ >偏钨酸铵/CeO₂ >磷酸+偏钨酸铵/CeO₂ >磷酸/CeO₂。由于磷钨酸改性的CeO₂催化剂中P与W之间相互作用，导致磷钨酸/CeO₂催化剂表面弱酸及中强酸含量较多，Ce物种和O物种相对活跃，有利于NH₃的吸附、活化和NH₃-SCR反应的进行；因此，磷钨酸改性的CeO₂催化剂活性最佳，在225-450℃下NO转化率高于90%。
- 酸改性 /
- 磷钨酸 /
- 氧化铈 /
- 选择性催化还原 /
- NO脱除
Abstract: A series of CeO₂ catalysts was modified with different acids including phosphotungstic acid (P-W), phosphate acid (P), partial ammonium tungstate (W), and phosphate acid plus partial ammonium tungstate (P+W); the effect of acid modification on the performance of CeO₂ catalyst in the selective catalytic reduction of NO with ammonia (NH₃-SCR) was then investigated. The results indicated that the CeO₂ catalyst after acid modification possesses abundant surface acid sites of weak-medium strength and the acid quantity of various catalysts follows the order of P-W/CeO₂ >W/CeO₂ >P+W/CeO₂ >P/CeO₂. Due to the interaction between P and W species, the P-W/CeO₂ catalyst modified with phosphotungstic acid exhibits high amount of weak-medium surface acid sites and active Ce and O species, which may promote the adsorption and activation of NH₃ and then enhance its catalytic activity in the NH₃-SCR of NO; over the P-W/CeO₂ catalyst, the conversion of NO keeps above 90% at 225-450℃.
- acid modification /
- phosphotungstic acid /
- CeO₂ /
- selective catalytic reduction with ammonia /
- NO removal

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图 1 实验装置示意图

Figure 1 Schematic diagram of the experimental apparatus

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图 2 不同催化剂的XRD谱图

■: CeO₂; ◆: WO₃; ●: silicate species

Figure 2 XRD patterns of different catalysts

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图 3 不同催化剂的H₂-TPR谱图

Figure 3 H₂-TPR profiles of different catalysts

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图 4 不同催化剂的NH₃-TPD谱图

Figure 4 NH₃-TPD profiles of different catalysts

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图 5 不同催化剂的红外光谱谱图

Figure 5 FT-IR spectra of different catalysts

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图 6 不同催化剂的Ce 3d XPS谱图

Figure 6 Ce 3d XPS spectra of different catalysts

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图 7 不同催化剂的O 1s XPS谱图

Figure 7 O 1s XPS spectra of different catalysts

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图 8 不同催化剂的NH₃-SCR活性

Figure 8 Activity of different CeO₂ catalysts in NH₃-SCR of NO

■: CeO₂; ●: P-W/CeO₂; ▲: W/CeO₂; ▼: P+W/CeO₂; ◆: P/CeO₂

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图 9 SO₂对催化剂P-W/CeO₂的NH₃-SCR活性的影响

Figure 9 Influence of SO₂ on the catalytic activity of the P-W/CeO₂ catalyst in NH₃-SCR of NO

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表 1 不同催化剂的物理化学性质

Table 1 Properties of various CeO₂ catalysts

Sample	A_BET /(m²·g^-1 )	Acidity (a.u.)	Ce³⁺/(Ce³⁺+Ce⁴⁺)	O_α/(O_α+O_β+O_γ)
P-W/CeO₂	13	664	0.146	0.350
W/CeO₂	15	312	0.142	0.281
W+P/CeO₂	12	304	0.221	0.330
P/CeO₂	6	239	0.304	0.242
CeO₂	18	94	0.170	0.142
note: surface area A_BET is determined from nitrogen adsorption data by BET method; acidity is calculated from NH₃-TPD profiles; surface atomic ratios of Ce³⁺/(Ce³⁺+Ce⁴⁺) and O_α/(O_α+O_β+O_γ) are determined by XPS

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