CeO_2-TiO_2复合纳米纤维光催化降解醛酮类污染物的研究

采用同轴静电纺丝法制备了CeO2-TiO2复合纳米纤维,并用X射线衍射仪、扫描电子显微镜、程序升温脱附仪和紫外-可见光谱能谱(UVVis)仪表征了CeO2-TiO2纳米纤维的相组成和微观形貌,分析了CeO2-TiO2纳米纤维对醛酮的吸附强度与光电化学特性.同时,研究了CeO2配比量、光源条件和重复使用性对降解甲醛污染物的影响规律.结果表明,CeO2质量配比为50%的CeO2-TiO2催化剂对甲醛降解效率最高;在无光和可见光条件下,CeO2-TiO2催化剂对甲醛的降解效率分别为13.5%和25.3%,在紫外光下CeO2-TiO2催化剂对甲醛的降解效率为92.5%;随着光催化循环次数的增加,可见光下CeO2-TiO2催化剂对甲醛的降解效率逐渐增高,紫外光下CeO2-TiO2催化剂对甲醛的降解效率维持在92.5%左右.利用催化剂样品CT50对柴油机尾气中醛酮类排放污染物进行光催化降解的应用发现,CeO2-TiO2催化剂对醛类污染物的降解效率为85.4%,酮类污染物的降解效率为81.3%,苯甲醛和甲基苯甲醛的降解效率分别为80.4%和80.3%.表明CeO2-TiO2催化剂具有较强的光催化降解醛酮类污染物的能力.

Preparation of CeO2-TiO2 composite nanofibers for photocatalytic degradation of aldehyde and ketone

In this study, CeO₂-TiO₂ composite nanofibers were prepared by the coaxial electrospinning method. The crystalline phase and microstructure of CeO₂-TiO₂ catalysts were displayed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Formaldehyde adsorption intensity and photoelectrochemical properties of CeO₂-TiO₂ catalysts were characterized by temperature programmed desorption (TPD) and ultraviolet-visible spectrometry (UV-Vis). The corresponding influence factors on CeO₂ doped quantity, light condition and repeated performance were analyzed. The test results showed that when the doping amount of CeO₂ was 50%, formaldehyde degradation rate was the highest. Formaldehyde degradation efficiencies were 13.5% and 25.3% respectively in dark and visible light conditions, and it was about 92.5% in UV-light condition. With the increase of photocatalytic cycles, formaldehyde degradation efficiency gradually increased under visible light, but it was remained at 92.5% under UV-light. Aldehyde, ketone, benzaldehyde and p-methyl benzaldehyde were reduced by catalyst sample (CT50) in diesel engine exhaust emission, with the degradation efficiencies of 85.4%, 81.3%, 80.4% and 80.3%, respectively. Therefore, it is verified that CeO₂-TiO₂ catalyst had better photocatalytic activity in reducing aldehyde and ketone emissions from diesel engine exhaust.