Effect of zeolite framework composition on the fast NH3-SCR performance of hydrothermally aged iron zeolites

IF 12.2 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Journal of Hazardous Materials Pub Date : 2025-05-02 DOI:10.1016/j.jhazmat.2025.138487

Xuechao Tan , German Sastre , Suk Bong Hong

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Abstract

Here we report that iron-exchanged borosilicate and gallosilicate beta zeolites when hydrothermally aged at high temperatures show a notable increase (ca. 30 and 45 %, respectively) in NO_x conversion under fast SCR conditions at 150 °C. We also found that their lowest hydrothermal aging temperatures leading to such a conversion increase are higher by 50 °C and lower by 100 °C than the temperature (650 °C) of iron-exchanged aluminosilicate beta, respectively, indicating a strong influence of zeolite framework composition on the low-temperature fast NH₃-SCR activity of zeolite-supported iron catalysts. Combined experimental and theoretical characterizations provide indirect but convincing evidence for the formation of neutral heteronuclear bis-μ-oxo ironboron or irongallium dimers in the hydrothermally aged catalysts, which can effectively catalyze the reduction of ammonium nitrate, an intermediate of the NH₃-SCR reaction with a decomposition temperature of ca. 180 °C, by NO at 150 °C.

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沸石骨架组成对水热老化铁沸石快速NH3-SCR性能的影响

在这里，我们报道了铁交换硼硅酸和没水硅酸β沸石在高温水热老化后，在150°C的快速SCR条件下，NOx转化率显著提高（分别约为30%和45%）。我们还发现，导致这种转化率提高的最低水热老化温度分别比铁交换铝硅酸盐β的温度（650℃）高50℃和低100℃，这表明沸石骨架组成对沸石负载铁催化剂的低温快速NH3-SCR活性有很大影响。实验和理论相结合的表征为水热老化催化剂中形成中性异核双μ-氧硼铁或铁镓二聚体提供了间接但令人信服的证据，该二聚体可以在150℃下有效催化NH3-SCR反应的中间产物硝酸铵的还原，分解温度约为180℃。

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来源期刊

Journal of Hazardous Materials 工程技术-工程：环境

CiteScore

25.40

自引率

5.90%

发文量

3059

审稿时长

58 days

期刊介绍： The Journal of Hazardous Materials serves as a global platform for promoting cutting-edge research in the field of Environmental Science and Engineering. Our publication features a wide range of articles, including full-length research papers, review articles, and perspectives, with the aim of enhancing our understanding of the dangers and risks associated with various materials concerning public health and the environment. It is important to note that the term "environmental contaminants" refers specifically to substances that pose hazardous effects through contamination, while excluding those that do not have such impacts on the environment or human health. Moreover, we emphasize the distinction between wastes and hazardous materials in order to provide further clarity on the scope of the journal. We have a keen interest in exploring specific compounds and microbial agents that have adverse effects on the environment.