控制燃煤锅炉的汞排放是我国减少重金属汞排放的关键，研发高效低成本的脱汞材料对燃煤烟气汞污染控制具有重要意义。铈是丰度最高的稀土元素，其氧化物具有无毒性、低成本等特点，且铈氧化物具有优异的储氧能力和氧化还原反应活性，使其在烟气脱汞领域具有较大的应用潜力。综述了含铈材料在烟气脱汞领域的最新研究进展，分析了含铈材料各种制备方法的特点，并指出其分子模型构建的关键；介绍了含铈材料的脱汞性能，探讨了炭基材料和非炭基材料的发展现状；论述了主要燃煤烟气组分对含铈材料脱汞性能的影响，重点关注了SO2、H2O、NO、HCl、NH3和O2等对单质汞脱除的促进或抑制机理；最后对含铈脱汞材料的研究进行展望。研究表明，浸渍法制备含铈材料简单易得，但活性成分均匀性难以保证，共沉淀法不适用于负载量低的样品，溶胶凝胶法可实现分子水平的均匀混合，模板法、水热法和溶剂热法制得的样品分散性好，火焰法则有待进一步发展，含铈材料分子模型的构建需考虑铈含量、铈分散状态；物理吸附、化学吸附和催化氧化对含铈材料脱汞均有贡献；低浓度SO2有助于汞氧化，但高浓度SO2会在铈氧化物表面与汞竞争吸附；相比其他材料，含铈材料的抗H2O性能更佳；NO可与含铈材料中的氧反应生成NO2促进汞氧化；向含铈材料中添加CuO可缓解NH3对脱汞的不利影响；HCl与O2对脱汞效率的促进程度受铈氧化物含量影响。在已有研究基础上，含铈脱汞材料在商业化应用前仍有以下问题亟待解决：汞与烟气组分在含铈多元金属材料表面的竞争机制或协同脱除机理，含铈材料的环境影响，含铈材料在实际烟气中的脱汞性能，脱汞反应器及脱汞装置的设计及优化，含铈脱汞材料的技术经济性研究。基于现有试验和模拟研究，总结了含铈材料的脱汞性能及烟气组分对单质汞吸附、氧化的影响机制，并提出了未来工作重点，为含铈材料在烟气脱汞领域的发展和应用奠定理论基础。

Controlling mercury emission from coal-fired boilers is the top priority of mercury reduction in China. It is of great significance to develop efficient and low-cost mercury removal materials for mercury pollution control from coal-fired flue gas. Ce is the most abundant rare earth element, and cerium oxide has the virtues of non-toxicity and relatively inexpensive. More importantly, excellent oxygen storage capacity and redox reaction activity of cerium oxide make it have great application potential in the field of mercury removal. The latest research progress of cerium-containing materials in removing mercury from flue gas was reviewed. The various preparation methods of cerium-containing materials were analyzed, and the key points for building the molecular model of cerium-containing catalysts or adsorbents were emphasized. The mercury removal performance of cerium-containing materials was introduced, and the direction for future study on carbon-based materials and non-carbon-based materials were discussed. The influences of the main flue gas components on the mercury removal performance of cerium-containing materials were discussed in detail. The promotion or inhibition mechanisms of SO2、H2O、NO、HCl、NH3 and O2 on the elemental mercury removal were summarized. Finally, the prospects of the research on cerium-containing mercury removal materials were proposed. The results show that the preparation of cerium containing materials by impregnation is simple, but the uniformity of the active components is hard to achieve. The coprecipitation method is unsuitable for low loading samples. The sol-gel method can ensure uniform mixing at the molecular level. The materials prepared through template method, hydrothermal method and solvothermal method have good dispersion characteristics, while the flame synthesized catalysts still need further development. The content of cerium and the cerium dispersion state should be considered in the construction of cerium-containing materials molecular model. Physisorption, chemisorption and catalytic oxidation all contribute to the mercury removal from cerium-containing materials. Low concentration SO2 is favorable for Hg oxidation, but high concentration SO2 will compete with Hg for the adsorption sites on cerium oxide surface. Cerium-containing materials have better resistance to H2O compared with other materials. NO can  react with oxygen in cerium containing materials to produce NO2 and promote the oxidation of Hg. Adding CuO to cerium-containing materials can alleviate the adverse effect of NH3 on mercury removal. The promotion degree of HCl and O2 on mercury removal efficiency is affected by cerium oxide content. Based on the existing research, the following problems are still to be solved before the commercial application of cerium-containing mercury removal materials: competition or synergistic removal mechanisms of mercury and flue gas components on the surface of cerium-containing polymetallic materials; environmental impact of cerium-containing materials; mercury removal performance of cerium-containing materials in practical flue gas, design and optimization of mercury removal reactor and mercury removal unit, techno-economic study of cerium-containing materials. Based on the experimental and simulation investigations from the literature, the mercury removal performance of cerium-containing materials and the influence mechanisms of flue gas components on the adsorption and oxidation of elemental mercury were summarized. The focus of future work was proposed,  in order to lay a foundation for the development and application of cerium-containing materials in the field of flue gas mercury removal.

0 引言

1 样品制备与计算模型构建方法

   1.1 样品制备

   1.2 模型构建

2 含铈材料的脱汞性能

   2.1 炭基含铈材料

   2.2 非炭基含铈材料

3 烟气组分的影响

   3.1 SO2的影响

   3.2 H2O的影响

   3.3 NO的影响

   3.4 其他烟气组分的影响

4 结语和展望