Mixed-matrix membranes (MMMs) are promising candidates to improve the competitiveness of membrane technology against energy-intensive conventional technologies. In this work, MMM composed of poly(octylmethylsiloxane) (POMS) and activated carbon (AC) were investigated with respect to separation of higher hydrocarbons (C3+) from permanent gas streams. Membranes were prepared as thin film composite membranes on a technical scale and characterized via scanning electron microscopy (SEM) and permeation measurements with binary mixtures of n-C4H10/CH4 under varying operating conditions (feed and permeate pressure, temperature, feed gas composition) to study the influence on separation performance. SEM showed good contact and absence of defects. Lower permeances but higher selectivities were found for MMM compared to pure POMS membrane. Best results were obtained at high average fugacity and activity of n-C4H10 with the highest selectivity estimated to be 36.4 at n-C4H10 permeance of 12 mN3/(m2·h·bar). Results were complemented by permeation of a multi-component mixture resembling a natural gas application, demonstrating the superior performance of MMM.

A new kind of gas permeation membrane is developed to separate higher hydrocarbons (C 3+ ) from permanent gases. State of the art for such gas permeation applications are membranes based on solubility selective, rubbery polymers, which offer high permeances but relatively low selectivities. The new membrane is designed to improve selectivity, and therefore, significantly reduce energy demand and size of a gas separation plant. The membrane is based on the mixed matrix concept and consists of a rubbery polymer matrix with incorporated activated carbon particles. This two phase separation layer forms a solubility selective mixed matrix membrane by combining the advantages of both materials. The separation of n-C 4 H 10 /CH 4 mixtures is investigated. Based on experimental results a new concept for a transport model for mixed matrix membrane is introduced.

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