silicone rubber is a highly active adsorbent material, is an amorphous substance, its chemical molecular formula is mSiO2-nH2O Because it is a hydrate, the temperature is too high will first lose crystalline water, the loss of crystalline water is not called silica, but called silica Therefore, silica only the highest use temperature, no melting point, silica: SiO2 is also known as silica. It is widely distributed in nature, such as quartz, quartz sand, etc. White or colorless, with high iron content is light yellow. Density 2.2 ~ 2.66. Melting point 1670 ℃ (scale quartz); 1710 ℃ (square quartz). Boiling point 2230 ℃, the relative dielectric constant is 3.9. 
The maximum temperature for regeneration of various industrial silica gel should not exceed the following limits.
Coarse pore silica gel shall not be higher than 600℃.
Fine pore silica gel shall not be higher than 200°C.
Blue gum indicator (or discolored silica gel) shall not be higher than 120℃.
Silicone aluminum rubber shall not be higher than 350 ℃.
After the regeneration of silica gel, its moisture is generally controlled at 2% or less can be put back into use