溶胶-凝胶法制备载体硅胶研究进展

Research Progress of Silica Gel Prepared by Sol-Gel Method

溶胶-凝胶法包括一次溶胶-凝胶和反复溶胶-凝胶两种工艺。一次溶胶-凝胶工艺主要有两种,一是以碱性溶液为底液,并流方式加入无机酸和硅酸盐,或是以单股流的方式加入无机酸;二是以酸性溶液为底液,采用单股流的方式加入硅酸盐。这种制备工艺的特点在于能够获得大孔径、高比表面积的硅胶,然而对于孔分布及孔结构的调整受限。反复溶胶-凝胶工艺主要是以酸性溶液为底液,过程中加入碱性介质及有机醇溶剂,同时配合水热反应。这种制备工艺能够准确控制载体硅胶的孔结构及孔分布,并能大幅提升硅胶的比表面积,从而提高催化剂活性。

Sol-gel method includes a sol-gel and repeated sol-gel two processes. A sol-gel process there are two main ways：First, the alkaline solution as the bottom liquid, cocurrent and adding inorganic acids and silicates, or a single stream of inorganic acids;the second is acidic solution as the end of the liquid, the use of a single stream of silicate solution is added. This preparation process is characterized by the ability to obtain a silica gel with a large pore size and a high specific surface area, however, the adjustment of pore distribution and pore structure is limited. Repeated sol-gel process is mainly acidic solution as the bottom liquid, the process of adding alkaline medium and organic alcohol solvent, at the same time with the hydrothermal reaction. The preparation process can accurately control the pore structure and pore distribution of the carrier silica and can greatly increase the specific surface area of the silica gel to improve the catalyst activity.