화학공학소재연구정보센터
Journal of the Korean Industrial and Engineering Chemistry, Vol.7, No.4, 794-801, August, 1996
졸-겔법에 의한 TiO2 미분말 합성과 반응메카니즘(I):Titanium isopropoxide의 가수분해
Synthesis of TiO2 Fine Powder by Sol-Gel Process and Reaction Mechanism(Ⅰ) : Hydrolysis of Titanium Isopropoxide
초록
Isopropanol 용매 내에서 titanium isopropoxide(Ti(O-iPr)4)의 가수분해반응에 의하여 TiO2 미분말을 합성하였고 가수분해 반응 속도를 자외선분광법에 의하여 측정하였다. 반응은 Ti(O-iPr)4)의 농도에 비하여 물 농도를 크게 하여 유사일차반응으로 진행시켰고, 물 농도 및 온도의 변화에 따른 반응속도상수를 Guggenheim method로 계산하였다. 또한 물의 동위원소 효과를 측정하여 반응에 참여하는 물분자의 촉매성을 확인하였다. 입도분석과 미세구조 관찰 결과, 얻어진 TiO2 미분말은 0.3㎛정도의 입자크기를 갖는 구형의 입자로 확인되었다. 또한 반응속도로부터 전이상태에 참여하는 n value와 열역학적 파라메타를 계산한 결과, Ti(O-iPr)4)의 가수분해반응은 이분자 반응인 SN 2 mechanism으로 진행하는 것으로 추정되었다.
TiO2 fine powders were synthesized via hydrolysis reaction of titanium isopropoxide in isopropanol solvent and the reaction rates were studied by use of UV spectroscopic method. The reactions were controlled to proceed to pseudo-first-order reaction in the presence of excess water in isopropanol solvent. The rate constants which varied with temperature and concentration of water were calculated by Guggenheim method. Reactions using D2O were also carried out to determine the catalytic character of water. n value of water molecules in transition state and the thermodynamic parameters showed that the reaction proceeded by SN2 mechanism. TiO2 powders synthesized in this reaction were almost spheric forms and had average particle sloe of 0.3㎛ diameter.
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