催化学报

催化学报 ›› 2017, Vol. 38 ›› Issue (12): 2085-2093.DOI: 10.1016/S1872-2067(17)62952-8

• 论文 • 上一篇    下一篇

高热稳定性TiO2空心微球高效光催化氧化丙酮

梁丽a,b, 李开宁a, 吕康乐a, 何永基b, 段有雨a   

  1. a 中南民族大学资源与环境学院催化材料科学国家民委-教育部重点实验室, 湖北武汉 430074;
    b 香港教育大学科学与环境学系, 香港新界大埔
  • 收稿日期:2017-10-11 修回日期:2017-10-30 出版日期:2017-12-18 发布日期:2017-12-29
  • 通讯作者: 吕康乐, 何永基
  • 基金资助:

    国家自然科学基金（51672312，21373275）；武汉市科技计划（2016010101010018，2015070504020220）；香港教育大学院长研究基金（04257）.

Highly photoreactive TiO2 hollow microspheres with super thermal stability for acetone oxidation

Li Lianga,b, Kaining Lia, Kangle Lva, Wingkei Hob, Youyu Duana   

  1. a Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission & Ministry of Education, Hubei Province, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074, Hubei, China;
    b Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, N. T., Hong Kong, China
  • Received:2017-10-11 Revised:2017-10-30 Online:2017-12-18 Published:2017-12-29
  • Supported by:

    This work is supported by the National Natural Science Foundation of China (51672312, 21373275), the Science and Technology Program of Wuhan, China (2016010101010018, 2015070504020220), and the Dean's Research Fund-04257 from the Education University of Hong Kong.

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摘要：

空心结构材料具有低密度、高通透性和易于回收的优点，因此人们对空心球的TiO2，如TiO2空心微球（TiO2-HMSs）的制备非常感兴趣.但是普通TiO2-HMSs的热稳定性较差，一般在600℃以上就由活性较高的锐钛矿相相变成活性很差的金红石相.考虑到氟离子能够抑制TiO2相变，因此我们以Ti（SO4）2为钛源，在NH4F和H2O2的共同作用下，于180℃水热制备了由空心颗粒自组装成的表面氟化的TiO2-HMSs，并考察了其热稳定性与光催化氧化分解丙酮的性能.
研究发现，当焙烧温度从300℃上升到1000℃时，TiO2平均粒径从79.0 nm逐渐增大到97.7 nm，结晶度从1.00增大到1.53.这是由于热处理促进了TiO2颗粒的晶化.当进一步升温到1100℃时，XRD谱开始出现金红石相TiO2的特征衍射峰，此时约18.4%的锐钛矿相开始向金红石相转化.因此，本文制备的二氧化钛锐钛矿相可以稳定到1000℃，显示出优良的高热稳定性.
扫描电镜显示，水热制备的TiO2-HMSs是由高能（001）面暴露的TiO2十面体纳米晶组装而成.随着焙烧温度提高到900℃，空心微球外观没有显著改变，但是组装体纳米晶暴露出来的空洞逐渐变小，晶粒变得圆滑；至1100℃时，空心微球组装体的纳米晶变成了球形颗粒，但是空心微球的空心结构没有坍塌，空心微球结构依然得到保留.
我们用丙酮的紫外光催化氧化分解来评价不同温度焙烧的TiO2空心微球的光催化活性.结果显示，前驱体TiO2空心微球于300℃焙烧2 h，丙酮的氧化速率从1.39×10-3 min-1（前驱体）降至0.82×10-3 min-1（T300样品），这是因为样品表面吸附的氟离子受热挥发所致；当焙烧温度从300℃提高到900℃时，催化剂活性从0.82×10-3 min-1升至2.09×10-3 min-1，这是由于焙烧促进了TiO2的晶化；进一步升至1000和1100℃时，催化剂活性显著下降，这是由于催化剂的比表面积急剧减小和金红石相的生成.
总之，本文利用氟离子的化学诱导作用制备出表面氟化的空心颗粒自组装TiO2空心微球，该TiO2空心微球显示出超高热稳定性与高光催化活性，因此在高热环境中具有实际应用前景.

关键词: 二氧化钛空心微球, 光催化氧化, 丙酮, 氟化, 热稳定性

Abstract:

TiO2 hollow microspheres (TiO2-HMSs) have attracted much attention because of their high photoreactivity, low density, and good permeability. However, anatase TiO2-HMSs have poor thermal stability. In this study, surface-fluorinated TiO2-HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2-NH4HF-H2O2 solution at 180℃. The effect of the calcination temperature on the structure and photoreactivity of the TiO2-HMSs was systematically investigated, which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation. We found that after calcination at 300℃, the photoreactivity of the TiO2-HMSs decreases from 1.39×10-3 min-1 (TiO2-HMS precursor) to 0.82×10-3 min-1 because of removal of surface-adsorbed fluoride ions. With increasing calcination temperature from 300 to 900℃, the building blocks of the TiO2-HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles, and the photoreactivity of the TiO2-HMSs steady increases from 0.82×10-3 to 2.09×10-3 min-1 because of enhanced crystallization. Further increasing the calcination temperature to 1000 and 1100℃ results in a decrease of the photoreactivity, which is ascribed to a sharp decrease of the Brunau-er-Emmett-Teller surface area and the beginning of the anatase-rutile phase transformation at 1100℃. The effect of surface-adsorbed fluoride ions on the thermal stability of the TiO2-HMSs is also discussed.

Key words: TiO2 hollow microsphere, Photocatalytic oxidation, Acetone, Fluorine, Thermal stability