摘 要：通过正硅酸乙酯（TEOS）在超临界乙醇－水－氨介 质中的反应合成出具有规则形状和大小均匀的 SiO2 颗粒 并通过透射电子显微镜（TEM）和扫描电子显微镜（SEM）对 颗粒进行了表征。同时通过调节体系中乙醇／水的摩尔比 例改变临界温度和压力可以调变合成产品的颗粒大小。 同时为避免 TEOS 在升温过程中与水发生反应TEOS 的加 入通过液体高压进样泵来完成。另外不同组成的混合介质 的临界温度和压力通过跟踪具有相同配比不同总体积的体 系的压力－温度曲线的分叉点来确定。
关键词：超临界系统；SiO2 颗粒；正硅酸乙酯
Abstract： The reaction of tetraethylorthosilicate （TEOS） was conducted in supercritical medium composed of ethanolwater and ammonium as catalyst．The addition of TEOS was carried out by using a high-pressure pump to avoid the reactions to wards water during the heating process．As a resultvery regular and uniform silica particles were obtained after the reaction con ducted in the supercritical medium for 24h．The particle size could be adjusted by changing the molar ratio of ethanol to wa ter and consequently the critical temperature and pressure．T he critical temperature and pressure of the mixed medium was de termined from the separating point of the p－ T curves that pos sessed different total volume but the same composition．
Keywords： supercritical system；regular silica particles；tetra ethylorthosilicate
