The performance and mechanism of Ag-doped CeO2/TiO2 catalysts in the catalytic oxidation of gaseous elemental mercury
The performance and mechanism of Ag-doped CeO2/TiO2 catalysts in the catalytic oxidation of gaseous elemental mercury
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DOI：
10.1039/c4cy01745e
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发表时间：
2015-04
影响因子：
5
通讯作者：
Songjian Zhao;Zan Qu;N. Yan;Zhen Li;Haomiao Xu;Jian Mei;Fuquan Quan
中科院分区：
文献类型：
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作者：
Songjian Zhao;Zan Qu;N. Yan;Zhen Li;Haomiao Xu;Jian Mei;Fuquan Quan
为了提高CeO 2/TiO 2催化剂催化气态元素汞氧化的能力，引入了银。Ag掺杂能显著提高CeO 2/TiO 2的Hg 0氧化能力。此外，温度窗口被加宽（从150 ° C到450 °C）。采用TEM、XRD、XPS和H2-TPR等手段对催化剂进行了表征。结果表明，银纳米粒子可以负载在TiO 2载体上。添加银后催化剂的结晶性和氧化还原能力得到改善。银主要以金属态存在，使Ce保持较高的Ce（IV）态。CeO 2将HCl氧化为活性Cl，然后吸附在银纳米粒子上。除HCl和Hg 0穿透实验外，还进行了Hg 0脱附实验和Cl 2产率实验，研究了不同温度范围内单质汞氧化的催化机理，结果表明，低温下反应遵循Langmuir-Hinshelwood机理，高温下遵循Eley-Rideal机理和均相气相反应.此外，汞的价态变化实验表明，HCl是主要的催化氧化组分。
To improve the ability of CeO2/TiO2 catalysts to catalyze the oxidation of gaseous elemental mercury, silver was introduced. Doping with Ag can significantly enhance the Hg0 oxidation ability of CeO2/TiO2. In addition, the temperature window was widened (from 150 to 450 °C). The catalysts were characterized by TEM, XRD, XPS and H2-TPR. The results indicated that silver nanoparticles can be loaded on the TiO2 support. The catalysts had better crystallization and higher redox ability after addition of silver. Silver existed mostly in its metallic state, which can keep Ce in a higher Ce(IV) state. HCl was oxidized into active Cl by CeO2 and then was adsorbed on the silver nanoparticles. In addition to the HCl and Hg0 breakthrough experiments, a Hg0 desorption experiment and a Cl2 yield experiment were conducted to study the catalytic mechanisms of elemental mercury oxidation over various temperature ranges; these experiments indicated that the reaction followed the Langmuir–Hinshelwood mechanism at low temperature, and the Eley–Rideal mechanism and homogeneous gas-phase reaction at high temperature. Furthermore, a mercury valence state change experiment was performed, which indicated that HCl was the major catalytic oxidization component.