Silica applied as mixed matrix membrane inorganic filler for gas separation: a review

The trade-off relationship between gas permeability and selectivity is well-known as the primary barrier to developing polymeric membranes for the gas separation process. Mixed matrix membranes (MMMs) can be promoted as a solution to produce the desired membrane for gas separation processes. The general idea for synthesizing MMMs is to induce the thermal, electrical, mechanical, and molecular sieve properties of these nano materials into the base membrane. The incorporation of silica particles with molecular sieving properties in the polymer matrix is expected to lead to higher permeability and/or higher selectivity, compared to polymeric membranes. This paper reviews various types of silica incorporated into a polymer matrix and their gas transport mechanisms, MMM preparation methods and effect of silica on MMM characteristics and gas separation performance. MMM gas transport models after silica incorporation are also reviewed. In addition, the challenges and future works in developing MMMs with silica particles as inorganic filler are discussed.