利用溶胶-凝胶法调节pH及添加PEG优化酒精纯化用SiO_2粉末(英文)

Optimizing Sol-Gel Derived SiO_2 Powders for Purification of Ethanol by Tuning pH and Addition of Polyethylene Glycol

该工作探讨利用TEOS前驱液及不同含量、不同分子量PEG制备出SiO2粉末的性质.SiO2粉末由溶胶-凝胶法制备,并结合退火前后烘干.TEOS前驱溶液的水解及缩合反应速率在pH=3时比在pH=5,7,9时进行得更彻底,且随温度及PEG分子量的升高而升高;粉末产率在TEOS前驱液pH=3时达到最大.与不加PEG的溶胶-凝胶法制备出的样品相比,加入PEG制备的粉末有更高的吸水能力.若粉末从高至500℃退火,则可发现乙醇浓度增加.依据液体和固体NMR、电子显微镜以及BET结果,对吸水及粉末表面积之间的关系进行了讨论.

This study explores the properties of the SiO2 powders prepared from tetraethyl orthosilicate （TEOS） pre-solution with and without incorporating polyethylene （PEG） of different molecular weights. SiO2 powders were prepared by the sol-gel method in combination with oven-drying before and after annealing. The hydrolysis and condensation reactions of TEOS pre-solution at pH 3 occur more thoroughly than that at pH 5, 7, and 9. The rate of hydrolysis and condensation is found to increase with temperature and the molecular weight of PEG for pre-solution and a maximum in the powder yield is reached for TEOS pre-solution at pH 3. The powder prepared from the TEOS pre-solution added with PEG is superior to that without adding PEG, with a higher water adsorption capacity. With the powders annealed at a temperature up to 500 ~C, the ethanol concentration was found to be increased. In addition, the relation between water adsorption and surface area of SiO2 powders for purification of ethanol is discussed based on both liquid and solid state nuclear magnetic resonance （NMR） spectroscopies, scanning electron microcopy （SEM） and BET.