Adsorption and Oxidation of Elemental Mercury over Ce-MnOx/Ti-PILCs

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• 作者：Chuan He ; Boxiong Shen ; Jianhong Chen ; Ji Cai
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：July 15, 2014
• 年：2014
• 卷：48
• 期：14
• 页码：7891-7898
• 全文大小：465K
• ISSN：1520-5851

文摘

A series of innovative Ce鈥揗n/Ti-pillared-clay (Ce鈥揗n/Ti-PILC) catalysts combining the advantages of PILCs and Ce鈥揗n were investigated for elemental mercury (Hg⁰) capture at 100鈥?50 掳C in the absence of HCl in the flue gas. The fresh and used catalysts were characterized by scanning electron microscopy (SEM), nitrogen adsorption鈥揹esorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalyst characterization indicated that the 6%Ce-6%MnO_x/Ti-PILC catalyst possessed a large specific surface area and high dispersion of Ce and Mn on the surface. The experimental results indicated that the 6%Ce-6%MnO_x/Ti-PILC catalyst exhibited high Hg⁰ capture (>90%) at 100鈥?50 掳C. During the first stage of the reaction, the main Hg⁰ capture mechanism for the catalyst was adsorption. As the reaction proceeded, the Hg⁰ oxidation ability was substantially enhanced. Both the hydroxyl oxygen and the lattice oxygen on the surface of the catalysts participated in Hg⁰ oxidation. At a low temperature (150 掳C), the hydroxyl oxygen and lattice oxygen from Ce⁴⁺ 鈫?Ce³⁺ and Mn³⁺ 鈫?Mn²⁺ on the surface contributed to Hg⁰ oxidation. However, at a high temperature (250 掳C), the hydroxyl oxygen and lattice oxygen from Mn⁴⁺ 鈫?Mn³⁺ contributed to Hg⁰ oxidation. Hg⁰ oxidation was preferred at a high temperature. The 6%Ce-6%MnO_x/Ti-PILC catalyst was demonstrated to a good Hg⁰ adsorbent and catalytic oxidant in the absence of HCl in the flue gas.