Electrospun cerium-based TiO2 nanofibers for photocatalytic oxidation of elemental mercury in coal combustion flue gas.
Electrospun cerium-based TiO2 nanofibers for photocatalytic oxidation of elemental mercury in coal combustion flue gas.
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DOI：
10.1016/j.chemosphere.2017.07.049
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发表时间：
2017-10
期刊：
影响因子：
8.8
通讯作者：
Lulu Wang;Yongchun Zhao;Junying Zhang
中科院分区：
文献类型：
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作者：
Lulu Wang;Yongchun Zhao;Junying Zhang
光催化氧化法是治理富汞烟气的一种有吸引力的方法。在本研究中，我们制备了一种新型的CeO_2纳米纤维，并选择其作为脱除烟气中汞的催化剂。从而阐明了这些纳米纤维的物理/化学性质。考察了焙烧温度、CeO掺杂量和不同光照条件对光催化脱除Hg0的影响。此外，还对紫外光照射下CeO2纳米纤维去除Hg0的机理进行了探讨。结果表明，400℃焙烧的催化剂具有较好的催化性能。在二氧化钛中加入0.3wt%的Ce，在紫外光照射下的脱色率最高，达到91%。所制备的样品在测试中显示出良好的稳定性，可长期使用。然而，添加CeO2的纳米纤维的光致发光强度明显低于Ti02，这归因于更好的光电子-空穴分离。虽然UV和O2是影响Hg0脱除的重要因素，但催化剂的参与对Hg0脱除的促进作用更为明显。Ce~(3+)和Ce~(4+)的共存导致Hg0的有效氧化。Hg2+是脱除Hg0反应的最终产物。结果，可以显著地抑制烟道气中汞的排放。这表明，将光催化技术与CeO_2纳米纤维相结合是一种有效降低HgO的有效策略。
Photocatalytic oxidation is an attractive method for Hg-rich flue gas treatment. In the present study, a novel cerium-based TiO2nanofibers was prepared and selected as the catalyst to remove mercury in flue gas. Accordingly, physical/chemical properties of those nanofibers were clarified. The effects of some important parameters, such as calcination temperature, cerium dopant content and different illumination conditions on the removal of Hg0using the photocatalysis process were investigated. In addition, the removal mechanism of Hg0over cerium-based TiO2nanofibers focused on UV irradiation was proposed. The results show that catalyst which was calcined at 400 °C exhibited better performance. The addition of 0.3 wt% Ce into TiO2led to the highest removal efficiency at 91% under UV irradiation. As-prepared samples showed promising stability for long-term use in the test. However, the photoluminescence intensity of nanofibers incorporating ceria was significantly lower than TiO2, which was attributed to better photoelectron-hole separation. Although UV and O2are essential factors, the enhancement of Hg0removal is more obviously related to the participation of catalyst. The coexistence of Ce3+and Ce4+, which leads to the efficient oxidation of Hg0, was detected on samples. Hg2+is the final product in the reaction of Hg0removal. As a consequence, the emissions of Hg0from flue gas can be significantly suppressed. These indicate that combining photocatalysis technology with cerium-based TiO2nanofibers is a promising strategy for reducing Hg0efficiently.