Generally speaking, silica gel can be divided into organic silica gel and inorganic silica gel according to their properties and components. According to its composition and shape, it can be divided into extruded silica gel and molded silica gel. Inorganic silica gel is a kind of highly active adsorption material. It is usually prepared by reaction of sodium silicate and sulfuric acid, aging, acid bubble and other post-treatment processes. Silica gel is an amorphous substance with the chemical formula of msio2.nh2o. It is non-toxic, non-toxic, non-toxic, non-toxic, non-toxic, non-toxic, non-toxic and water-soluble. Different types of silica gel have different microporous structures due to their different manufacturing methods. The chemical composition and physical structure of silica gel determine that it has many characteristics that other similar materials are difficult to replace: high adsorption performance, good thermal stability, chemical stability, high mechanical strength, etc. Organic silica gel is a kind of organosilicon compound, which contains Si-C bond and at least one organic group is directly connected with silicon atom. It is also used to regard those compounds that connect organic base and silicon atom through oxygen, sulfur, nitrogen, etc. Among them, polysiloxanes with SiO2 bond (- Si-O-Si -) as the skeleton are the most numerous, the most deeply studied and the most widely used in organosilicon compounds, accounting for more than 90% of the total amount. Extrusion of silica gel is common. For example, the sealing ring on the rice cooker is called the silica gel sealing ring. Molding silica gel is a little more complex, irregular shape, including silicone bowl, silica gel ice grid, silicone cake mold, etc.