【摘要】 在流化床反应器中 ,利用六甲基二硅胺烷 ( HMDS)对气相法制备的纳米二氧化硅进行了表面包覆 ,研究了包覆温度、包覆时间、HMDS分压等对纳米二氧化硅表面羟基、含碳量、p H值的影响 ,分析了表面包覆后气相法白炭黑的形态与结构。结果表明气相法白炭黑表面包覆 HMDS后 ,团聚状态得到明显改善 ;随着处理时间的延长 ,温度的升高以及 HMDS分压的升高 ,经表面处理后的白炭黑的 p H值和含碳量增加 ,表面羟基数明显减少。反应时间小于 1 5 min时 ,包覆速率较快 ,然后趋于平缓 ;反应温度小于 2 5 0°C时 ,温度对包覆效果影响较大 ,温度大于 40 0°C则影响较小 ;HMDS分压较低时 ,分压对包覆效果影响较大 ,当分压超过 7.9k Pa,则影响甚微更多还原

【Abstract】 Fumed silica was modified with hexamethyldisilazane (HMDS) in a fluidized bed reactor, and then the structure and morphology of it were characterized by TEM, FTIR etc. The results indicate that the agglomeration of fumed silica is restrained by HMDS modification. The pH value of fumed silica and its carbon content in fumed silica increase and silanol groups on its surfaces decrease with the increasing modification time, temperature and HMDS partial pressure. The coating rate of HMDS is high at the first 15min, and then decreases rapidly with coating time. The coating rate is strongly dependent on the reaction temperature and HMDS partial pressure when the modification temperature and HMDS partial pressure is less than 250°C and 7.9kPa respectively.更多还原