Einaga Hisahiro, Ibusuki Takashi, Futamura Shigeru
National Institute of Advanced Industrial Science and Technology, AIST Tsukuba West, 16-1, Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
Environ Sci Technol. 2004 Jan 1;38(1):285-9. doi: 10.1021/es034336v.
Gas-solid heterogeneous photocatalytic oxidation of aromatic compounds in air was carried out at room temperature with a fixed bed flow reactor. The deposition of Rh on TiO2 catalyst improved the catalyst durability in benzene photooxidation. The Rh deposition reduced the amounts of carbonaceous materials on the catalyst surface that were the cause of catalyst deactivation. The highest reaction rate was obtained at the Rh loading of 0.5-1.0 wt %. The Rh/TiO2 catalyst was gradually deactivated in prolonged benzene photooxidation, due to the increasing amount of carbonaceous materials on the catalyst surface. XPS studies showed that the gradual deactivation was related to the changes in the oxidation state of the surface Rh metals. The catalysts were regenerated by the treatment of hydrogen reduction after the photoirradiation in humidified air, indicating that Rh(0) was essential for the improvement of the catalyst durability. The catalyst was also regenerated by the heat treatment in N2 flow instead of the hydrogen reduction. Rh deposition was also effective for the improvement of catalyst durability in toluene photooxidation.
在室温下，使用固定床流动反应器对空气中的芳香族化合物进行气固多相光催化氧化。Rh负载在TiO₂催化剂上提高了催化剂在苯光氧化中的耐久性。Rh的负载减少了催化剂表面导致催化剂失活的含碳物质的量。在Rh负载量为0.5 - 1.0 wt%时获得了最高反应速率。由于催化剂表面含碳物质的量增加，Rh/TiO₂催化剂在长时间的苯光氧化中逐渐失活。XPS研究表明，这种逐渐失活与表面Rh金属氧化态的变化有关。在潮湿空气中光照射后，通过氢还原处理使催化剂再生，这表明Rh(0)对于提高催化剂耐久性至关重要。该催化剂也可通过在N₂气流中进行热处理而非氢还原进行再生。Rh负载对于提高甲苯光氧化中催化剂的耐久性也有效。
