二氧化鈦奈米孔洞分子篩之合成及光催化反應

Synthesis and photocatalytic reaction of titania nanoporous materials.

唐崇耀(Chong-Yao Tang)

指導教授 ： 鄭吉豐

中原大學/理學院/化學研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500789

摘要

摘要
一般界面活性劑使用在二氧化矽透過靜電、氫鍵、共價鍵和凡得瓦爾力作用形成中孔洞分子篩，而這種合成分子篩材料的技術延伸到二氧化鈦上，我們使用P123高分子界面活性劑進行合成奈米尺度二氧化鈦中孔洞分子篩，經過400和450℃鍛燒，可以發現銳鈦礦和金紅石的混晶，之後透過XRD、氮氣吸脫附、SEM、TEM、UV光譜和FT-IR光譜分析。
我們合成出表面積介於143 and 71 m2/g之間高活性的二氧化鈦分子篩，約40～80nm不等的中孔洞顆粒，而孔洞大小約5～15nm，經過不同溫度的鍛燒，造成表面氫氧基縮合，結晶相轉換和孔洞擴大甚至崩壞，在本文中建議可行的二氧化鈦中孔洞分子篩形成機構。
我們使用亞甲基藍進行光催化分解反應，改變pH值、氣體環境、光源波長、和觸媒及亞甲基藍濃度等參數，比較二氧化鈦中孔洞分子篩和工業用二氧化鈦P25的光催化效果，在通入氮氣或空氣環境下，合成出的二氧化鈦光催化效果略高於P25，原因在於銳鈦礦和金紅石混合的比例以及表面氫氧基的多寡。在溶液pH值為3的時候光催化效果最好，因為酸性環境下，會產生較多的HO2 自由基，有助於光催化分解反應的進行。

關鍵字

光催化反應 ； 光觸媒 ； 亞甲基藍 ； 二氧化鈦

並列摘要

Abstract
Surfactants have been shown to organize silica into a variety of mesoporous forms, through the mediation of electrostatic, hydrogen -bonding, covalent and van der waals interactions. This approach to mesostructured materials has been extended, to titanium dioxide. Nanoscaled mesoporous titania with mixed phases of anatase and rutile has been synthesized using P123 block copolymer surfactant under mild condition and further calcinations at 400 and 450℃.The resulting materials were characterized by XRD, nitrogen adsorption, TEM, SEM analysis, UV-vis spectroscopy and FT-IR spectroscopy.
The surface areas for most samples are between 143 and 71 m2/g. The nanoporous titania has nano-size between 40-80 nm and worm-like pore with wide pore size distribution between 5 and 15 nm. The calcination of resulting materials at different temperature will promote titanol group condensation, crystallization with phase transformations and enlarge pore at beginning. A reasonable mechanism for this phenomenon is proposed as well.
Parameters such as pH, gaseous environment, light wavelength and concentration of catalyst and MB(methylene blue) were studied using the photocatalytic decolorization of MB in a photoreactor. All experiments were performed in a quartz tube with UV light, a wavelength at 365 nm and 306 nm, in combination with a mesoporous TiO2 powder as the catalyst. Resulting material shows slightly higher conversion of MB than the P25 effective commercial photocatalyst under saturated aqueous solution with air or nitrogen. The results can be illustrated due to mixed phases and abundant titanol group of catalyst.
The optimal tentative conditions were develop in a solution at pH of 3.0. These results suggest that nano-scaled nanoporous TiO2/UV photocatalysis may be envisaged as a method for treatment of diluted waste water.

並列關鍵字

titania ； photocatalytic degradation ； photocatalysis ； methylene blue

參考文獻

18. Tomoki, T.; Naoko, K.; Ikuichiro, I.; Norio, I.; Masahiro, T.; Michio, I. J. Mater. Chem., 2002, 12, 1391.

74. Wu, N. L.; Wang, S. Y.; Rusakova, I. A. Science 1999, 285, 1375.

30. Tseng, I. H.; Chang, W. C.; Wu, C. S. Appl. Catal. B: Environmental 2002, 37, 37.

2. Anpo, M.; Chiba, K. J.Mole. Catal., 1992, 74, 207.

7. Fox, M. A.; Dulay, M. T. Chem. Rev., 1993, 93, 341.