合成均一粒徑球形二氧化鈦; Synthesis of monodisperse spherical titania

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Title:	合成均一粒徑球形二氧化鈦;Synthesis of monodisperse spherical titania
Authors:	方嘉偲;Chia-Szu Fang
Contributors:	化學工程與材料工程研究所
Keywords:	均一粒徑球形粉末;水熱裂解;四氯化鈦;分散劑;二氧化鈦;titanium tetrachloride;thermal hydrolysis;monodisperse spherical powders;dispersant;titania
Date:	2002-06-17
Issue Date:	2009-09-21 12:20:38 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	二氧化鈦廣泛的應用在塗料、光觸媒、填料、披覆材料等。而均一粒徑之球型粉體是近年來對陶瓷粉體的研究重點。此粉體可增加燒結體的緻密度，並降低粉體之燒結溫度。製備二氧化鈦有釵h方法，如：溶凝膠法，但成本昂貴且水解速率快，不易控制。或以水為溶劑之強制水解法或均一沉澱也可得到，但卻受限於濃度太低且反應時間太長之缺點。在本研究中，依據溶劑之溶解度會隨著介電常數減少而降低的原理，以正丙醇和水在四氯化鈦的混合溶劑，於70℃下加熱，以製備均勻分散球型之二氧化鈦。影響製備的條件都將被討論，如：合成的溫度、時間、醇水比、反應物的濃度、分散劑的濃度等，都將被討論。沉澱物的型態是受到混合溶劑中醇水比的控制，二氧化鈦合成時，調整醇與水的體積比，觀察對粉體外型的影響，當醇水比為3時，可得到最像球型且分散的二氧化鈦。當再加入分散劑時，會使得分子分散的最好。當分子在不同固態含量中都會形成二氧化鈦，只是會隨著濃度的增加顆粒變大。當反應溫度不同，分子會變得較不均勻且粒徑會隨著溫度的增加而變大，而反應時間的增加，也會使分子粒徑變大。利用不同醇類來製備二氧化鈦時，正丙醇、異丙醇及丙酮都能形成球型二氧化鈦，而甲醇與乙醇則不容易形成，因其介電常數越低越容易形成二氧化鈦。將製備得到的二氧化鈦以X-ray繞射分析為非晶相，當鍛燒溫度為600℃時，為銳鈦礦結構，而鍛燒到800℃時，則為板鈦礦結構。 Titania has been used extensively in pigment, cosmetics, photocatalyst and coatings. It has been reported that the spherical powders with a narrow size distribution is the most desirable state. Many methods such as sol-gel process, forced hydrolysis and the homogeneous precipitation have been used to prepare TiO2 particles. However, there are some drawbacks: the concentration of reacting species is too low and the reaction time is too long. In this research, titania powders were synthesized by thermal hydrolysis of TiCl4 in a mixed solvent of n-propanol and water. The morphology of the precipitates was controlled by the volume ratio of n-propanol to water (RH ratio) of the mixed solvent. The titania sample synthesized at an RH ratio of 3 was spherical and discreted. Adding hydroxypropyl cellulose (HPC) as a steric dispersant made particles well-discrete. The particles in different solid contents were all spherical but the size increased with an increase of the solid content. When the temperature was 80-100℃, the morphology and the size were the same approximately. After the temperature increased to 150℃, the size became bigger (1.5μm). The particles at 200℃ was also much bigger than that at 150℃ (2.0μm ). The TiO2 particle was much smaller by using supersonics oscillator than those prepared by the conventional stirring, due to the less temperature gradient in the solution. The particle size was bigger and the size distribution was broader as the reaction time was longer. It was not easy to form titania in methanol and ethanol solvents. In n-propanol, isopropanol, and acetone, the titania was easier to be formed. The lower the dielectric constant is, the easier the spherical titania forms. The phase of particles was analyzed by X-ray. The phase transformed with different calcinations temperature were amorphous, anatase, and rutile.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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