Silica Gel is a porous, amorphous form of silica (SiO₂). Due to its unique internal structure, silica gel is radically different from other SiO₂-based materials. It is composed of a vast network of interconnected microscopic pores.

As opposed to zeolites, silica gels have larger pores with a wide range of diameters – typically between 5 Å and 3000 Å – and do not allow for the separation of molecules based solely on their size.

During the manufacturing process, it is possible to adjust the pore size range to best fit application needs.

• Silica gels synthesized with an average pore size of about 20Å are known as narrow pore silica gels
• Silica gels with an average pore size of about 110Å and beyond are called wide pore silica gels

Silica gels maintain their structure when activated. Activation frees the large internal surface area and pore volume, enabling physical adsorption and capillary condensation.

Silica gel is extremely pure by industrial standards due to the absence of noticeable concentrations of metallic compounds like aluminum, iron or heavy metals. Therefore pure silica gel is much less active as a catalyst than other adsorbents like zeolites or aluminas, which means unwanted reactions like cracking reactions in hydrocarbon streams and resulting coke formation can be minimized.

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