醇類及矽源於中孔洞 SBA-1 之合成研究;Phase control of SBA-1 mesostructures induced by tetra-n-alkoxysilanes or via alcohol-assisted synthesis

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6170

Title:	醇類及矽源於中孔洞 SBA-1 之合成研究;Phase control of SBA-1 mesostructures induced by tetra-n-alkoxysilanes or via alcohol-assisted synthesis
Authors:	鄭仲志;Chung-Chih Cheng
Contributors:	化學研究所
Keywords:	中孔洞;SBA-1
Date:	2005-06-29
Issue Date:	2009-09-22 10:14:40 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文主要探討利用 cetyltriethylammonium bromide (C16TEABr) 界面活性劑作為中孔洞材料的模板 (template) 並以 TEOS (Tetraethyl orthosilicate) 當作矽源，在高酸性條件下影響中孔洞 SBA-1 合成的參數。本文的研究可分成三個部分探討。首先，添加具有較高親水性的醣類如蔗醣 (Sucrose) 於反應中，經過變化各種反應條件，從 XRD 結果發現不僅成功合成以 Cubic 堆積形式的 SBA-1，而且經過水洗測試依然保有原本 SBA-1 的結構，證明添加 Sucrose 於合成中有穩定 SBA-1 結構的作用。第二部分，使用 TMOS (Tetramethyl orthosilicate)、TEOS (Tetraethyl orthosilicate)、TPOS (Tetrapropyl orthosilicate) 與 TBOS (Tetrabutyl orthosilicate) 這四種矽化物當作合成的矽源，由於這四種矽源的水解速度為: TMOS > TEOS > TPOS > TBOS，導致在相同的反應條件下，產生不同結構和外觀型態的中孔洞材料，經由 XRD (Powder X-ray diffractometer)、SEM (Scanning Electron Microscope) 與TEM (Transmission Electron Microscope) 等儀器鑑定，結果顯示以 TMOS 當作矽源的 SBA-1 材料具有最佳的孔洞結構，而且只須一個小時以內的反應時間，即可快速合成出 SBA-1。第三部分則是在反應過程中，添加不同親水程度的醇類，使用的醇類包括: 甲醇、乙醇、正丙醇、正丁醇、甘油與 D-sorbitol。反應溫度升高或是添加長碳鏈的醇在合成中，導致 SBA-1 產生結構與外觀型態的轉變。由 XRD 與 SEM 的結果得知，當樣品顆粒的外觀呈現十四面體，其結構為 Cubic；而其外觀呈現螺旋體，則材料的結構為 hexagonal。 The silica-surfactant mesostructures have been formed by tetraethyl orthosilicate and hexadecyltriethylammonium bromide under strongly acidic conditions. First, the synthesis conditions have been optimized in order to obtain the well-ordered cubic (Pm3n) mesostructure via sucrose-assisted synthesis. The stability of the materials toward washing with water was improved by increasing the synthesis time from 4 to 48 hr. Secondly, tetra-n-alkyl orthosilicates with different chain lengths have been also used as the silicate sources. We found that the ability for the preservation of the cubic (Pm3n) mesophase at high temperatures depends on the type of silicate sources, following the order TBOS < TPOS < TEOS < TMOS. The use of TMOS, rather than TEOS, as a silicate source not only prevents the phase transformation in the conventional synthesis of SBA-1 at temperatures above 313 K, but also allows the rapid formation of the cubic mesostructure within one hour at 323 K. Finally, the addition of alcohols offers an effective synthetic approach for controlling the phase behavior of cubic SBA-1 (Pm3n mesophase) over a broad temperature range. The cubic Pm3n mesophase can be stabilized at high synthesis temperatures, simply by adding short-chain alcohols such as methanol and ethanol, or polyols (glycerol and D-sorbitol) as cosolvents during the synthesis. The addition of medium-chain alcohols like 1-butanol, on the other hand, results in the formation of a hexagonal mesophase rather than a cubic mesophase.
Appears in Collections:	[Graduate Institute of Chemistry] Electronic Thesis & Dissertation

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