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    Zn掺杂α-羟基氧化铁脱除高炉煤气中H2S性能研究

    Performance Study on Zn-Doped α-FeOOH in Removing H2S from Blast Furnace Gas

    • 摘要: 高炉煤气中硫化氢(H2S)的脱除对实现钢铁行业超低排放具有重要意义。高炉煤气经余压透平发电装置(Blast Furnace Top Gas Recovery Turbine Unit, TRT)后,温度在50~80 ℃之间,宜选用低温下活性较高的针铁矿(α-FeOOH)作为高炉煤气水解后H2S的吸附剂。采用共沉淀结晶法将不同摩尔比(1%、5%、11%)的Zn2+掺杂到α-FeOOH中,在模拟的高炉煤气气氛中,利用固定床-气相色谱联用平台测试其对H2S的吸附容量,Zn/FeOOH硫容提升至292.2 mg/g,提高了137%。采用BET、EPR、XPS等分析手段对吸附剂的理化性质进行表征,分析结果表明,Zn/FeOOH样品的比表面积提升近60%。比表面积的增加意味着更多的反应界面可用于H2S的吸附和转化,更多的吸附位点是提高硫容的关键因素之一。此外,孔容积提升约116%,孔容积的增加可以缓解反应产物带来的孔道堵塞效应。在g=2.002的位置,Zn/FeOOH系列样品均出现了氧空位的特征峰,Zn/FeOOH-11样品表现出最高的氧空位信号强度,表明掺杂Zn后材料中的氧空位显著增加。当Zn2+被引入α-FeOOH晶格时,由于Zn2+和Fe3+的离子半径和电荷不完全匹配,其替代Fe3+会在晶格中引入局部应力和畸变,有助于氧原子从晶格中逸出,形成氧空位。氧空位能为H2S的吸附和活化提供活性位点,增强材料的催化活性。Zn掺杂α-FeOOH中单羟基比例增加到36%。单羟基是提高硫容的关键,作为活性较高的基团能够与H2S形成氢键,从而增强材料表面的吸附。通过原位红外光谱分析,表明Zn不仅作为催化剂的一部分,还直接参与H2S的反应形成ZnS,Zn掺杂不仅改善了α-FeOOH的催化性能,还影响了硫产物的种类。结构和表面性能的改变,显著提升了Zn/FeOOH材料对H2S的吸附和转化能力,为吸附剂硫容提高及高炉煤气净化技术应用提供了参考。

       

      Abstract: The removal of hydrogen sulfide (H2S) from blast furnace gas is crucial for achieving ultra-low emissions in the iron and steel industry. After passing through the top gas recovery turbine (TRT) unit, the blast furnace gas temperature typically ranges from 50 to 80 ℃. Ferric hydroxide (α-FeOOH) exhibits high activity at low temperatures, making it an ideal adsorbent for H2S after water treatment. α-FeOOH was doped with Zn2+ at different molar ratios (1%, 5%, and 11%) via co-precipitation crystallization. A combined fixed-bed and gas chromatography platform was used to evaluate the H2S adsorption capacity in the simulated blast furnace gas atmosphere. The results showed that the H2S adsorption capacity increased to 292.2 mg/g, a 137% improvement. The physical and chemical properties of the adsorbents were characterized using BET, EPR, and XPS. The results indicated a significant increase in the specific surface area of the Zn/FeOOH samples, rising by approximately 60%. This enhancement leads to more reaction interfaces available for H2S adsorption, providing additional active sites for H2S molecules, which is crucial for improving sulfur capacity. Additionally, the pore volume increased by about 116%, mitigating the pore blockage typically caused by reaction products. All Zn/FeOOH samples displayed characteristic peaks associated with oxygen vacancies at g = 2.002, with the Zn/FeOOH-11 sample showing the highest intensity of the oxygen vacancies. This suggests that Zn doping considerably boosts the oxygen vacancies within the material. The introduction of Zn2+ ions into the α-FeOOH lattice creates local stress and distortion due to the mismatch in ionic radius and charge between Zn2+ and Fe3+. This mismatch facilitates the escape of oxygen atoms, resulting in the formation of oxygen vacancies; these vacancies serve as active sites for the adsorption and activation of H2S molecules, thereby enhancing the catalytic activity of the material. Furthermore, the proportion of monohydroxyl groups in Zn-doped α-FeOOH increased to 36%. These monohydroxyl groups are pivotal for improving sulfur capacity, as they are highly active and can form hydrogen bonds with H2S molecules, further enhancing their adsorption on the material surface. In situ infrared spectroscopy analysis revealed that Zn functions as a catalyst component and also directly interacts with H2S to form ZnS. This Zn doping enhances the catalytic performance of α-FeOOH and influences the types of sulfur products generated. The alterations in structure and surface properties significantly enhance the adsorption and conversion capacity of Zn/FeOOH materials for H2S, providing a reference for increasing the sulfur capacity of the adsorbent and enhancing blast furnace gas purification technologies.

       

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