水热衰老增强氧化物减少比铁交换的化物在150°C
Xuechao Tan1, Pablo García-Aznar2, German Sastre2
1Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea.
Journal of the American Chemical Society
|February 22, 2024
概括
水热老化显著增加铁中低温氨选择性催化还原 (NH3-SCR) 的活性. 这一突破有助于从排气中去除氧化, 提供更有效的环境解决方案.
科学领域:
- 环境催化
- 材料科学
- 化学工程
背景情况:
- 使用铜和铁交换的焦化物进行氨选择性催化降解 (NH3-SCR) 对于从排气中去除氧化物 (NOx) 来说至关重要.
- 目前的NH3-SCR技术的一个主要局限性是其在低温下,特别是在150°C左右的低性能.
研究的目的:
- 调查水热老化对NH3-SCR的铁交换热质的低温活性的影响.
- 了解老化后增强的催化性能的结构和机制起源.
主要方法:
- 在650°C或更高的温度下对Fe-β,Fe-ZSM-5和Fe-ferrierite热石进行水热老化.
- 在150°C的快速NH3-SCR条件下对老化的催化剂进行评估.
- 催化剂结构的表征和密度函数理论 (DFT) 计算的应用以阐明反应机制.
主要成果:
- 在水热老化过程中,Fe-β,Fe-ZSM-5和Fe-ferrierite的NOx转化在150°C时从大约30%增加到80%.
- 一种由老化Fe-beta和新鲜Cu-SSZ-13组成的复合催化剂实现了近90%的NOx转化.
- DFT计算表明,与单核铁氧位相比,在老化过程中形成的中性异核 bis-μ-oxo铁二聚体位表现出较低的激活自由能量.
结论:
- 水热老化是一种有效的策略,可显著增强铁交换热石的低温NH3-SCR活性.
- 提出新 bis-μ-oxo 二元活性位点的形成是提高催化性能的关键因素.
- 这一发现为开发在较低工作温度下更高效的废气排放控制催化剂提供了有希望的途径.
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