Study on Effect of Calcination and Ag Loading on Ag/TiO2 Catalyst for Low-Temperature Selective Catalytic Oxidation of Ammonia

IF 2.3 4区化学 Q3 CHEMISTRY, PHYSICAL Catalysis Letters Pub Date : 2024-11-09 DOI:10.1007/s10562-024-04833-5

Bin Guan, Junyan Chen, Zhongqi Zhuang, Lei Zhu, Zeren Ma, Xuehan Hu, Chenyu Zhu, Sikai Zhao, Kaiyou Shu, Hongtao Dang, Tiankui Zhu, Zhen Huang

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Abstract

Herein, Ag/TiO₂ NH₃-SCO catalyst was prepared by impregnation-rotary evaporation method with different calcination temperature and Ag loading content. The results of performance evaluation and characterization showed that the 10 wt% Ag/TiO₂ catalyst calcined at 500 °C showed the best comprehensive performance, with T₉₉ reaching 175 °C and N₂ selectivity reaching 80% at high temperatures. High-temperature calcination will lead to a significant decline in catalyst activity, accompanied by the transformation of TiO₂ from anatase to rutile phase and the obvious change and loss of Ag active sites, which greatly reduces the NH₃ adsorption and redox ability, but it can still maintain a high N₂ selectivity due to unchanged reaction mechanism. In addition, with the increase of Ag loading, excess Ag on Ag/TiO₂ will form metal clusters due to the lack of sufficient anchor points, which helps to improve NH₃-SCO activity. However, excessive Ag loading will reduce the specific surface area and acidic sites, and the Ag species on the catalyst surface will also change to the form of larger particles of Ag₂O, which will lead to the decline of catalytic performance.

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氨的低温选择性催化氧化中 Ag/TiO2 催化剂的煅烧和银负载效应研究

本文采用浸渍-旋转蒸发法制备了不同煅烧温度和Ag负载量的Ag/TiO2 NH3-SCO催化剂。性能评价和表征结果表明，在 500 ℃ 下煅烧的 10 wt% Ag/TiO2 催化剂综合性能最好，高温下 T99 达到 175 ℃，N2 选择性达到 80%。高温煅烧会导致催化剂活性显著下降，伴随着 TiO2 由锐钛相转变为金红石相，Ag 活性位点发生明显变化和损失，从而大大降低了 NH3 的吸附和氧化还原能力，但由于反应机理不变，仍能保持较高的 N2 选择性。此外，随着 Ag 负载的增加，Ag/TiO2 上过量的 Ag 会因缺乏足够的锚点而形成金属簇，这有助于提高 NH3-SCO 活性。但是，过量的 Ag 负载会降低比表面积和酸性位点，催化剂表面的 Ag 物种也会转变为较大颗粒的 Ag2O，从而导致催化性能下降。

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来源期刊

Catalysis Letters 化学-物理化学

CiteScore

5.70

自引率

3.60%

发文量

327

审稿时长

1 months

期刊介绍： Catalysis Letters aim is the rapid publication of outstanding and high-impact original research articles in catalysis. The scope of the journal covers a broad range of topics in all fields of both applied and theoretical catalysis, including heterogeneous, homogeneous and biocatalysis. The high-quality original research articles published in Catalysis Letters are subject to rigorous peer review. Accepted papers are published online first and subsequently in print issues. All contributions must include a graphical abstract. Manuscripts should be written in English and the responsibility lies with the authors to ensure that they are grammatically and linguistically correct. Authors for whom English is not the working language are encouraged to consider using a professional language-editing service before submitting their manuscripts.