介孔二氧化矽負載二氧化鈦光觸媒之製備與研究

Abstract

摘要 本篇論文的研究重點可分為兩個部分:第一部份是製備負載型二氧化鈦光觸媒，尤其是可應用在紡織纖維的光觸媒，第二部份是開發使用可見光光源的二氧化鈦光觸媒。二氧化鈦被紫外光激發時，能產生電子-電洞對，對表面吸附物進行氧化還原反應，應用在空氣污染的問題上，可發揮除臭ヽ抗菌和去污等功效。但是，負載二氧化鈦在有機纖維材料上時，卻因為其受光激發所產生的強氧化力而破壞纖維材料。有鑑於此，本研究製備出介孔氧化矽材料，並在孔道內負載奈米粒徑的二氧化鈦，除了使孔道內二氧化鈦仍保有光催化降解能力外，光惰性氧化矽材質也可發揮阻隔二氧化鈦與有機纖維材料的直接接觸。負載型觸媒的合成方法包括共沉澱法及介孔氧化矽的後嫁接法，並試著利用微乳化法結合改良的介孔氧化矽合成法，成功的將二氧化鈦負載在介孔氧化矽的孔道內，解決共沉澱法造成二氧化鈦堆積在載體外表面的缺點。 另一個研究重點則是開發可見光光觸媒，使用四氯化鈦稀鹽酸溶液，經迴流法合成出有高表面積，具銳鈦礦晶相與金紅石晶相混合晶相的奈米顆粒二氧化鈦。藉由苯酚溶液在可見光 (419 nm)激發下的光降解反應，評估觸媒的光催化活性，結果證實所合成的含75%金紅石晶相 的混晶相二氧化鈦在419 nm可見光源激發下有很好的光催化活性，且優於商業化光觸媒Degussa P25。最後，並製備混合晶相的負載型二氧化鈦光觸媒，結果也證實混合晶相的二氧化鈦負載在介孔材料SBA-15的載體上仍然保有很好的可見光光催化活性。

Abstract This dissertatin studies the preparation and characterization of the photocatalyst in textile application and visible light photocatalyst. Heterogeneous photocatalysts have shown high efficiencies in the removal of pollutants including odors, micro- organisms, viruses, and volatile organic contaminants, commonly present in air and can resolve environment pollution problem. The photocatalyst was mixed into the textile fiber by either direct mixing or coating. However, the textile fiber itself was photo-degraded after exposure to sunlight because of the strong oxidizing power of the photocatalyst. In the present work, we attempt to prepare TiO2 particles encapsulated inside the pores of mesoporous silica materials by some preparation methods. The TiO2 supported catalysts were prepared by coprecipitation and on nano mesoporous silica(NMS) by consecutive grafting methods. Finally, we found the more useful method for TiO2 particles encapsulated inside the pores of mesoporous silica materials by one pot synthesis with the introduction of titania via the reverse microemulison and be incorporated into the final mesoporus silica product. In contrast to the coprecipitation method, which is quite facile the large TiO2 particles on the external surface of mesoporous SiO2 . Moreover, we attempt to convert the TiO2 absorption onset from the ultraviolet to the visible region using mixed phase titania. The sun can provide an abundant source of photons; however, UV light accounts for only a small fraction (~5%) of the sun’s energy compared to the visible region (45%). Nanocrystalline TiO2 of high surface area (100-230 m2/g) and with various anatase/ rutile ratios was prepared by refluxing TiCl4 acid diluted solutions. The photodegradation of phenol in water was investigated using these mixed anatase/rutile phases TiO2 as the catalysts. When using 419 nm visible light as the light source, the mixed phase TiO2 revealed higher photocatalytic activities in phenol decomposition than that of Degussa P25. When TiO2 nanoparticles with mixed phases were supported on mesoporous silica material. Under 419 nm irradiation, the SBA-15 supported mixed phase TiO2 showed better photocatalytic activities than Degussa P25,too.