TiO2-V2O5纳米纤维光催化氧化烟气中的Hg0

对静电纺丝法制备的TiO₂和TiO₂-V₂O₅纳米纤维进行光催化脱除模拟烟气中Hg⁰的研究。对纳米纤维进行了SEM、TEM、XRD、BET和UV-Vis检测。结果表明TiO₂-V₂O₅纳米纤维为锐钛矿,V₂O₅高度分散在TiO₂中。纤维直径在200 nm左右,由粒径为10 nm左右的微粒组成。掺杂V₂O₅后,纤维的吸光范围扩大,在可见光范围内的吸光度比纯TiO₂时有了很大提高。实验研究了不同光照条件、V₂O₅的掺杂量和循环次数对脱汞的影响,分析了TiO₂-V₂O₅催化脱汞的机理。当V₂O₅的质量含量为3%时,TiO₂-V₂O₅在可见光下的脱汞率可达到66%,比纯TiO₂时的7%有了显著提高;纤维的脱汞性能稳定,多次循环后紫外光和可见光下的脱汞率仍分别保持在80%和65%左右。电子的跃迁和电子、空穴的快速分离是TiO₂-V₂O₅在可见光下脱汞率提高的主要原因。

Photocatalytic oxidation of Hg0 in flue gas using TiO2-V2O5 nanofibers

Nanofibers of TiO₂ and TiO₂-V₂O₅ prepared by an electrospinning method were used to remove Hg⁰ in flue gas,and characterized by SEM,TEM,XRD,BET as well as UV-Vis.The TiO₂-V₂O₅ nanofiber is of anatase phase structure and V₂O₅ is highly dispersed in the fiber.Its average diameter is around 200 nm.The fiber is composed of a large number of nanoparticles with diameter around 10 nm. Compared with pure TiO₂,UV-Vis absorption intensity of TiO₂-V₂O₅ significantly increases and its absorption bandwidth also broadens.The mercury removal efficiencies under various illuminations,the optimum doping content of V₂O₅ as well as the capabilities to oxidize Hg⁰ for 8 cycles were also tested.In addition,mechanism analysis was used to reveal photocatalytic activity enhancement of TiO₂-V₂O₅ nanofibers.The result shows that 66% of Hg⁰ removal efficiency can be reached under visible irradiation at the sample with 3% V₂O₅ doping,and much higher than 7% for pure TiO₂.After eight cycles,Hg⁰ removal efficiencies over TiO₂-V₂O₅ still remain stable at 80% and 65% under UV and visible light respectively,indicating that this fiber catalyst could be used for long time.The increase of photocatalytic activity under visible light could be attributed to its electron transition and better photoelectron-hole separation.