SnNb2O6 纳米片上负载 CeO2-δ 纳米颗粒用于 NH3 选择性催化还原 NOx,ACS Applied Nano Materials

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SnNb2O6 纳米片上负载 CeO2-δ 纳米颗粒用于 NH3 选择性催化还原 NOx
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2022-09-12 , DOI: 10.1021/acsanm.2c03166
Xinyu Han _{1,

2} , Kaijie Liu _{1,

2} , Mengyao Bian _{1,

2} , Yangfei Fang _{1,

2} , Jiaying Sun _{1,

2} , Yibo Zhang _{1,

2,

3} , Xiangguang Yang _{1,

2}

Affiliation

_{NH 3}选择性催化还原（NH ₃ -SCR）是去除氮氧化物净化烟气的有效技术，催化剂在该技术中起着关键作用。为开发新型、高效、绿色、无钒催化剂，通过水热反应和固体反应成功合成SnNb ₂ O ₆纳米片，并通过XRD和TEM证实。这些纳米片首先用作CeO _{2-δ的载体，以制备用于NH}₃ -SCR的环保Ce/SnNb ₂ O ₆催化剂。这些 Ce/SnNb ₂ O ₆催化剂具有超过 90% 的 NO _x在 250–400 °C 下的转化率和 98% N ₂选择性以及 120,000 mL/(g·h) 的高空速，高于之前报道的 Ce 基 NH ₃ -SCR 催化剂的单位表面积性能。为了探索这种活性增加的因素，详细分析了 NH ₃ -TPD、H ₂ -TPR 和 XPS 数据。结果表明，Ce/SnNb ₂ O _{6纳米催化剂比Ce/SnO}₂和Ce/Nb ₂ O ₅具有更多的酸性位点和氧化位点。另外，Ce/SnNb ₂ O ₆的表面含有39.4%的Sn ⁴⁺离子，它们与 Ce 作为额外的氧化还原位点协同作用。Sn和Ce在界面处电子转移的作用促进了分子氧的形成和氧化还原位点的循环。动力学研究表明，Ce/SnNb ₂ O ₆的表观活化能为38.0 kJ/mol，降低了反应的难度。DFT研究表明，NH ₃在SnNb ₂ O ₆中的吸附能为429.7 kJ/mol，远高于其他常见载体，这意味着NH ₃更容易吸附在SnNb ₂ O _6上。纳米片，因此显示出更高的催化性能。此外，原位 DRIFTS 分析显示了主要机制的变化：L-H 和 E-R 机制在 300°C 时并存，而大多数反应在 400°C 时遵循 E-R 机制。这项研究可以为开发新的 Ce 基 NH ₃ -SCR 催化剂以控制固定源的 NO _x排放提供新的见解。

"点击查看英文标题和摘要"

CeO2−δ Nanoparticles Supported on SnNb2O6 Nanosheets for Selective Catalytic Reduction of NOx with NH3

Selective catalytic reduction with NH₃ (NH₃-SCR) is an effective technique for purifying flue gas by removing nitrogen oxides, and the catalyst plays a key role in this technology. For the purpose of developing novel, highly efficient, green, and vanadium-free catalysts, SnNb₂O₆ nanosheets were synthesized successfully by hydrothermal and solid reactions and confirmed by XRD and TEM. These nanosheets were first used as a support for CeO_2−δ to prepare environmentally friendly Ce/SnNb₂O₆ catalysts for NH₃-SCR. These Ce/SnNb₂O₆ catalysts had more than 90% NO_x conversion and 98% N₂ selectivity at 250–400 °C and a high space velocity of 120,000 mL/(g·h), which is higher than the per surface area performance of the previously reported Ce-based NH₃-SCR catalysts. To explore the factors for this increased activity, NH₃-TPD, H₂-TPR, and XPS data were analyzed in detail. The results indicated that Ce/SnNb₂O₆ nanocatalysts have more acid and oxidative sites than Ce/SnO₂ and Ce/Nb₂O₅. In addition, the surface of Ce/SnNb₂O₆ contained 39.4% Sn⁴⁺ ions, which synergize with Ce as additional redox sites. The effect of electron transfer between Sn and Ce at the interface promoted the formation of molecular oxygen and cycling of redox sites. Kinetic studies showed that Ce/SnNb₂O₆ had a low apparent activation energy of 38.0 kJ/mol, which reduced the difficulty of the reaction. DFT studies indicated that the adsorption energy of NH₃ in SnNb₂O₆ was 429.7 kJ/mol, which is much higher than that of other common supports, meaning that NH₃ is much easier to adsorb on SnNb₂O₆ nanosheets, therefore showing higher catalytic performance. Moreover, in situ DRIFTS analysis showed the changes in the dominant mechanisms: the L–H and E–R mechanism coexist at 300 °C, while most of the reactions follow the E–R mechanism at 400 °C. This study can provide new insights into the development of new Ce-based NH₃-SCR catalysts to control NO_x emissions from stationary sources.

更新日期：2022-09-12

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