二氧化鈦修飾中孔洞分子篩之合成、結構特性與光催化反應; Synthesis, Characterization and Photocatalytic Reaction of Titanium-modified Mesoporous Materials

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題名:	二氧化鈦修飾中孔洞分子篩之合成、結構特性與光催化反應;Synthesis, Characterization and Photocatalytic Reaction of Titanium-modified Mesoporous Materials
作者:	謝明宏;Ming-Hung Hsieh
貢獻者:	化學研究所
關鍵詞:	化學嫁接法;二氧化鈦;SBA-15;亞基甲藍光降解反應;MB photoblenching reaction;SBA-15;Chemical grafting method;Titianium dioxide
日期:	2009-01-12
上傳時間:	2009-09-22 10:19:11 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究利用化學嫁接法將二氧化鈦薄膜嫁接於 SBA-15 表面，修飾後的材料具有高比表面積及高規則的中孔洞結構，在亞甲基藍光降解反應中亦有相當優異的表現。 XRD 與 HRTEM 的結果顯示Ti/SBA R1nc 經由鍛燒處理後，鍛燒溫度的提高不會破壞材料結構的規則，且二氧化鈦的單分子層亦無晶相的特徵峰。若是比較 Ti/SBA R1c500、Ti/SBA R2c500 與 Ti/SBA R3c500，隨著迴流次數的增加，材料結構的規則性略微下降，比表面積由SBA-15的765 m2/g等間距下降至Ti/SBA R3c500的480 m2/g。ICP-OES的分析顯示含Ti量由Ti/SBA R1c500的6.5 wt% 增加至Ti/SBA R3c500的22.7 wt%。然而，經由水熱處理的Ti/SBA R1HT，其結構的規則性明顯下降許多且出現 TiO2 Anatase 晶相的特徵峰；在氮氣等溫吸附-脫附曲線中的遲滯迴圈，呈現 H3 type 的狹縫型孔洞，表示可能產生TiO2奈米顆粒堆積在原有規則孔道中，顯示孔道高度規則性已不復見，與 FESEM 看到的分子篩表面被TiO2 奈米顆粒緊密包覆的影像相符。亞甲基藍光催化降解實驗顯示水溶液中亞甲基藍的移除可分為吸附量與降解量兩部份。實驗結果顯示隨著鍛燒溫度的增加，對亞甲基藍的吸附量亦隨之增加，推測是高溫熱處理使二氧化鈦的單分子薄膜收縮，連帶裸露出擔體 SBA-15 的表面，造成吸附量的提升；在降解部分Ti/SBA R1c500 的光催化能力最佳，兩小時內可降解 42.8 % 的亞甲基藍，優於 Ti/SBA R1nc 的 36.8 %，一階反應常數k 值則由Ti/SBA R1nc的 0.0856 ( min-1 ) 增加到 0.1213 ( min-1 )。以水熱法處理的Ti/SBA R1H吸附量僅有12.9 %，兩小時內可降解 58.1%，其 k 值為0.1152 ( min-1 )。藉由增加化學嫁接的次數提昇材料的鈦含量，Ti/SBA R2c500與Ti/SBA R3c500的k 值大幅提升至0.2260 ( min-1 ) 與0.2001 ( min-1 )。然而，Ti/SBA R2HT與Ti/SBA R3HT的光催化活性與Ti/SBA R1HT相較並無顯著增加。本研究利用化學嫁接法並調控鍛燒溫度與嫁接次數的最適化，成功地製備出結構規則且二氧化鈦均勻批覆的中孔洞光觸媒材料，適度增加材料的含鈦量可使光催化降解亞甲基藍的活性提昇將近1倍。 In this study, the prepared SBA-15 was grafted with a TiO2 thin layer via chemical grafting method. The resulting TiO2-modified material with high surface area and well-ordered mesoporous structure can be demonstrated efficiency in MB photoblenching reaction. XRD and HRTEM images showed that under the process of calcination, Ti/SBA R1nc increase calcined temperature didn’t caused destroy of the structure of Ti/SBA R1nc, whereas TiO2 monolayer was hardly observed. Comparing Ti/SBA R1c500 , Ti/SBA R2c500 and Ti/SBA R3c500, we concluded that the surface areas decreased regularly with the increasing times of reflux from 765 m2/g ( SBA-15 ) to 480 m2/g ( Ti/SBA R3c500 ). ICP-OES revealed the contents of Ti had risen from 6.5% ( Ti/SBA R1nc ) to 22.7% ( Ti/SBA R3c500 ). However, the regularity of structure decreased enormously and TiO2 anatase phase characteristic peak was observed after hydrothermal treatment of Ti/SBA R1HT. The hysteresis loop of N2 adsorption-desorption isotherm presented that the slit from pore of H3 type, indicated the TiO2 nanoparticle had piled up and destroyed the high regularity of the original channels. The conclusion corresponded to the FESEM image which molecular sieves were tightly surrounded by TiO2 nanoparticles. The result of MB photoblenching reaction was exhibited by two parts: adsorption and degradation. In adsorption part, we assumed the higher calcined temperature could make TiO2 monolayer shrink and exposed the surface of SBA-15 that resulted in increase of MB adsorption. In degradation part, Ti/SBA R1c500 performed the best photocatalytic ability that decomposed 42.8% MB in 2 hours while Ti/SBA R1nc performed only 36.8%. K values of first-order reaction elevated from 0.0856 min-1 ( Ti/SBA R1nc ) to 0.1213 min-1 ( Ti/SBA R1c500 ). Ti/SBA R1HT under hydrothermal treatment adsorbed only 12.9% MB and decomposed 58.1% MB in 2 hours ( K = 0.1152 ). By incresing times of chemical grafting, the k values of 0.2260 min-1 and 0.2001 min-1. However, the photocatalytic activities of Ti/SBA R2HT and Ti/SBA R3HT didn’t perform such a significant improvement as Ti/SBA R1HT. In this study, we found the optimal condition by adjusting calcined temperature and grafting times and successfully prepared a photocatalytic material that nearly multiplied the degradation of MB photobleaching reaction.
顯示於類別:	[化學研究所] 博碩士論文

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