Silica gel is a rigid 3D network of colloidal silica. It is exclusively used as a support material for the active titanium (III) centers in Ziegler-Natta catalysts. Silica gel allows a controlled fragmentation leading to form uniform polymer particles with narrow particle size distribution and high bulk density. Silica gel is classified as below: a. Aquagel - pores are filled with water; b. Xerogel - by the process of evaporation, aqueous phase in the pores are removed; c. Aerogel - solvent removed by supercritical extraction