摘要：通过对用硅灰石与盐酸反应制备多孔高比表面积SiO₂最佳实验工艺条件的研究,确定了最佳试验工艺条件,即反应速度、反应时间、中和速度、反应最终pH值与SiO₂比表面积的关系,探讨了其合成的机理。研究结果表明,当pH≤1.0时,硅灰石与盐酸反应生成大量稳定的硅酸溶胶;反应最终(pH＝4.0)使硅酸水解和缩聚以及Si—O与OH基团氢键的形成以适宜的速度进行,形成弱交联、网状、低密度的硅酸凝胶,最终产物SiO₂的比表面积增大。

关键词： 硅灰石；比表面积；二氧化硅；机理

Abstract:Through a series experiments the best process conditions are ensured in the prepared porous SiO₂ powder with high surface area by wollastonite and acid．The optimum test condictions such as reaction rate time neutralization rate and relation between pH value and specific surface area of SiO₂ are determined．The synthetical mechanism is discussed．The results show that there exist a great deal of silicic acid sol with stable states during reaction when pH≤1．0．The hydrolysates and condensation polymers of silicic acid are obtained when pH=4．0 and the hydrogen bonds of Si－O and OH groups are formed in suitable rate which can makes sol to gel with infirmness connection reticulation and lower density and surface area of silica powder is higher． 

Keywords:wollastonite；surface area；silica；mechanism