Ce-Co/KIT-6介孔材料的制备及其脱汞性能的研究

以P123表面活性剂为模板,采用硬模板法制备了有序介孔材料KIT-6,以KIT-6为载体,Ce(NO_3)_2·6H_2O和Co(NO_3)_2·6H_2O为Ce和Co源,采用溶液浸渍法制备了负载型Ce-Co/KIT-6介孔材料。在模拟烟气条件下,利用固定床实验台架研究了Ce-Co/KIT-6材料对烟气中的单质汞(Hg0)的脱除性能。采用扫描电镜(SEM)、N_2吸附-脱附(BET)、X射线衍射分析(XRD)、傅里叶红外光谱分析(FT-IR)、氢气程序升温还原(H_2-TPR)以及热重分析(TGA)等方法对材料进行表征。结果表明,Ce和Co在KIT-6孔道内部高度分散,同时材料保持高度有序的孔道结构、比表面积高达495.2 m~2/g,孔径4.6 nm。脱汞实验结果表明,Ce-Co/KIT-6对Hg0的氧化吸附去除效率很高,250℃下对Hg0的氧化吸附去除效率高达95%以上,在这个过程中,O_2的存在明显促进了催化剂的脱汞能力。氧通过Ce-Co价态的变化进入金属结构中,再与汞发生反应是这个过程的主要机理。

Synthesis of mesoprous materials with Ce-Co/KIT-6 and its mercury removal performance

The oxidation activity of elemental mercury (Hg⁰) by transition metal modified KIT-6 was investigated using a simulated element mercury (Hg⁰) adsorption reactor. The physical and chemical propertied of the catalysts were characterized by scanning electron microscope (SEM), N₂ adsorption-desorption (BET), Fourier Transform Infrared spectroscopy (FT-IR) Analysis, H₂-Temperature programmed reduction (H₂-TPR), thermogravimetric analysis (TGA). The results show that Ce-Co/KIT-6 surface area and total pore volume of the catalysts decrease after the modification. However, the pore structure and distribution after modification have little variation. The mean pore size and BET surface area of mesoporous Ce-Co/KIT-6 are 4.6 nm and 495.2 m²/g, respectively. The Ce-Co/KIT-6 shows a high Hg⁰ adsorption efficiency without O₂, the removal efficiency of Hg⁰ is about 50.67%; moreover,it has a high Hg⁰ removal efficiency of O₂ above 95% for 250 ℃, the presence of O₂ greatly contributes to mercury removal capacity of the catalyst. Oxygen enters the metal structure through changes in the valence state of Ce-Co and reacts with mercury, which may be the main mechanism of this process.