Abstract:

Carbon and nitrogen co-doped TiO₂ nanotube photocatalysts were synthesized by hydrothermal sol-gel method using the precursors of tetrabutyl titanate, glucose and urea for the dopant sources of titanium, carbon and N elements, respectively. Subsequently, characterization on the structure of catalysts was conducted and the photocatalytic performance for chlorobenzene (CB) conversion reactions was evaluated. Response surface methodology (RSM) was employed to investigate the effects of molar ratios of C to Ti and N to Ti on the catalytic activities, and the optimum ratios of 0.49 and 0.28 for the catalyst (donated as 0.5C/0.3N-TiO₂) were achieved. Characterizations on the structure and morphology of catalysts were conducted by XRD and TEM techniques. In combination with UV-vis spectra, FI-IR and BET techniques, it suggested that carbon and nitrogen co-doped titania consists of anatase and rutile with larger surface area, of which the UV-vis absorption spectra were red-shifted to 500 nm of wavelength. Under conditions of 10% of relative humidity, 50 mg·m^-3 of initial concentration and 60 s of reaction time, the conversion ratio of CB reached 93.5%. The catalyst exhibited a relatively high removal ratio (over 80%) of CB under relative humidity ranging from 10% to 60%. Durability test showed the catalytic activities of CB conversion reactions slightly reduced after continuous running for over 10 h of reaction time.

Key words: catalysis, TiO₂, carbon and nitrogen co-dopants, optimal design, waste treatment

摘要：

以钛酸四丁酯为钛源、葡萄糖和尿素作为掺杂剂,采用水热-溶胶凝胶法制备了碳氮共掺杂TiO₂光催化剂,研究了该催化剂的结构特性及其对氯苯(CB)废气的转化性能。响应面法分析了C、N与钛酸四丁酯的添加比例对TiO₂催化CB的影响,获得了C和Ti物质的量比0.49、N和Ti物质的量比0.28时,该催化剂对CB的转化效率相对较高。利用XRD、TEM等对催化剂结构以及形貌进行表征表明:C/N共掺杂TiO₂为锐钛矿和金红石混合晶型,比表面积较大,吸收波长红移至500 nm。在反应介质相对湿度10%、CB初始浓度 50 mg·m^-3、反应时间60 s时,催化转化率93.5%;制备的催化剂在相对湿度10%~60%范围内对CB均具有较好的去除效果。稳定性实验表明,连续测试10 h对CB的转化率略微下降。

关键词: 催化, TiO₂, C/N共掺杂, 优化设计, 废物处理