催化学报

催化学报 ›› 2020, Vol. 41 ›› Issue (10): 1622-1632.DOI: 10.1016/S1872-2067(19)63508-4

• 论文 • 上一篇    下一篇

TiO2(B)多孔微球高湿光热催化降解NOx性能

马贺, 王长华, 李松美, 张昕彤, 刘益春   

  1. 东北师范大学物理学院, 紫外发射材料与技术教育部重点实验室, 吉林长春 130024
  • 收稿日期:2020-02-29 修回日期:2020-03-21 出版日期:2020-10-18 发布日期:2020-08-15
  • 通讯作者: 王长华, 张昕彤
  • 基金资助:
    国家自然科学基金（51072032，51372036，51102001）；教育部重点项目（113020A）；111计划（B13013）；吉林省科技发展规划（20180101175JC）.

High-humidity tolerance of porous TiO2(B) microspheres in photothermal catalytic removal of NOx

He Ma, Changhua Wang, Songmei Li, Xintong Zhang, Yichun Liu   

  1. Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, China
  • Received:2020-02-29 Revised:2020-03-21 Online:2020-10-18 Published:2020-08-15
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (51072032, 51372036, 51102001), the Key Project of Chinese Ministry of Education (113020A), the 111 project (B13013), and Jilin Province Science and Technology Development Plan (20180101175JC).

PDF

292

摘要： 近年来，半导体氧化物光催化技术由于反应条件温和，在消除环境空气中氮氧化物NOx（NO+NO2）方面得到了广泛的关注.然而，随着反应过程中湿度的逐渐增加，催化剂表面水的覆盖率也逐渐增加，从而导致许多光催化材料高湿失活.因此研发高湿条件下仍具有高活性的催化剂成为高效脱除大气环境中NOx的关键.本文制备了粒径为1-2μm，结晶度较高的单斜相TiO2（B）微球催化剂.BET和孔结构分析发现，TiO2（B）微球具有高比表面积的多孔结构.催化性能测试发现，TiO2（B）多孔微球在相对湿度为20%时，光热催化下的非NO2选择性高达99%；当相对湿度增至80%时仍保持在96.18%.相比之下，当反应气相对湿度从20%增加到80%时，标准商用二氧化钛P25的非NO2选择性却由95.02%降至58.33%，可见，TiO2（B）多孔微球在光热催化反应中具有较强的耐湿性.进一步研究发现，光热反应中，水在催化剂表面的覆盖率明显减少，从而促进了超氧自由基的形成.ESR自由基捕获实验表明，相较于室温下的光催化反应，光热条件下TiO2（B）微球的超氧自由基含量明显提升，更多的超氧自由基更有利于NO的深度氧化以及抑制毒副产物NO2的生成，从而有效提高了NOx的去除效率，并明显提升了非NO2选择性.原位红外光谱表明，相比于标准P25在光催化和光热催化过程中硝酸根与亚硝酸根含量与暗吸附过程中基本保持不变的情况，TiO2（B）微球在光催化过程中硝酸根的含量相较于暗吸附过程随时间的增加而明显增加，表明在光催化过程中更多的NO在TiO2（B）微球表面生成了更为稳定的含氮化合物；而在光热催化过程中，随反应时间的增加，催化剂表面的亚硝酸根含量逐渐减少，硝酸根含量明显增加，由此表明在光热催化条件下，TiO2（B）微球对NO的深度氧化促进作用明显优于标准商用P25.本文有助于耐湿性光热催化剂的设计，为炎热高湿气候下NOx的脱除提供了参考.

关键词: TiO2(B)多孔微球, 光催化剂, 光热催化, 耐湿性, NO降解

Abstract: Semiconductor oxides are widely used to achieve photocatalytic removal of NOx (NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis; however, many of them tend to be deactivated at high relative humidity (RH) levels. In the case of the benchmark P25 TiO2 photocatalyst, we observe a significant decrease in non-NO2 selectivity from 95.02% to 58.33% when RH increases from 20% to 80%. Interestingly, the porous TiO2(B) microspheres synthesized in this work exhibit 99% selectivity at 20% RH; the selectivity remains as high as 96.18% at 80% RH. The high humidity tolerance of the TiO2(B) sample can be ascribed to its strong water desorption capacity and easy O2 adsorption at elevated temperatures, which reflects the fact that the superoxide radical is the main active species for the deep oxidation of NOx. This work may inspire the design of efficient photothermal catalysts with application in NOx removal in hot and humid environments.

Key words: TiO2(B), Photocatalyst, Photothermal catalysis, High-humidity tolerance, NO degradation