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在SAPO-34和Cu/SAPO-34之间NH₃氧化机制的差异

Xiubin Ren¹, Yingfeng Duan¹, Wei Du²

¹School of Chemistry and Chemical Engineering, Xi'an University of Science and Technology Xi'an 710054 PR China xustduanyf@xust.edu.cn.

|March 5, 2024

概括

这项研究表明,孤立的Cu2+物种比Cu-SAPO-34催化剂增强了氨选择性催化还原 (NH3-SCR). 该机制涉及CuO和Brønsted酸的初始NO形成地点,然后在孤立的Cu2+地点产生N2.

科学领域:

催化剂是一种催化剂.
材料科学材料科学材料科学
环境化学环境化学

背景情况:

氨的选择性催化还原 (NH3-SCR) 对于从废气中去除氧化 (NOx) 是至关重要的.
了解NH3氧化机制对SAPO-34和Cu-SAPO-34等催化剂的理解对于优化SCR性能至关重要,特别是在高温下.

研究的目的:

阐明不同于SAPO-34和Cu-SAPO-34催化剂的NH3氧化机制.
确定负责NH3氧化的活性位点及其在NH3-SCR过程中的作用.
为了将催化剂结构,特别是Cu物种分布与催化活性相关联.

主要方法:

用于结构分析的X射线衍射 (XRD).
扫描电子显微镜 (SEM) 用于形态学.
对于Cu物种分布的H2温度编程脱吸 (H2-TPR).
关于NH3氧化的动力学研究.

主要成果:

在Cu/SAPO-34催化剂中增加孤立的Cu2+物种,与含量相关,增强了NH3-SCR活性.
NH3对SAPO-34的氧化主要发生在布伦斯特德酸位点,产生NO.
在Cu-SAPO-34上,NH3的氧化涉及一个两步机制:在CuO或Brønsted酸位点上初始NO的形成,然后在孤立的Cu2+位点上NO的降解为N2.

结论:

隔离的Cu2+物种是NH3氧化和N2形成的关键活性场所,在NH3-SCR过程中超过Cu-SAPO-34.
与原生SAPO-34.4相比,Cu物种的存在和分布显著改变了NH3的氧化机制.
了解这些机制可以了解/SAPO-34催化剂的高温性能,以减少氧化物.

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