在低温标准NH3-SCR中控制速度:EPR光谱和反应动力学的影响
Yiqing Wu1, Yue Ma1, Yilin Wang1
1Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99354, United States.
Journal of the American Chemical Society
|May 23, 2022
概括
这项研究表明,Cu/SSZ-13催化剂中的铜离子流动性是控制低温氨选择性催化还原 (NH3-SCR) 速率的关键. 增强的催化剂性能与铜离子在催化剂结构中更自由移动有关.
科学领域:
- 催化剂
- 材料科学
- 环境化学
背景情况:
- 对于控制氧化物排放而言,选择性催化还原 (NH3-SCR) 是至关重要的.
- 在低温NH3-SCR应用中,Cu/SSZ-13催化剂具有前景.
- 了解控制反应动力学的因素对于催化剂优化至关重要.
研究的目的:
- 阐明低温NH3-SCR对Cu/SSZ-13催化剂的速度控制因素.
- 研究铜物种化,流动性和催化活性之间的关系.
- 确定铜离子在NH3-SCR动力学中的作用.
主要方法:
- 七个不同铜负载的Cu/SSZ-13催化剂的合成 (Si/Al=6.7).
- 在低温条件下的标准NH3-SCR反应的动力学研究.
- 操作电子磁共振 (EPR) 光谱检测反应期间的铜物种和动态.
主要成果:
- 催化剂性能显示强烈依赖铜载荷,随着铜占用量的增加,原子效率显著增加.
- 间铜转移约束的释放被确定为增强氧化还原化学的主要因素.
- 操作EPR显示铜离子移动性与SCR动力学之间存在直接的相关性.
结论:
- 在低温稳态NH3-SCR中,具有动力相关的铜物种是表现出最高间移动性的物种.
- 短暂的双核铜种起着机械作用,它们的形成和解离对于低温动力学至关重要.
- 优化SSZ-13框架内的铜离子流动性对于提高低温NH3-SCR性能至关重要.
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