Polymer-based Membranes for Propylene/Propane Separation

Propane (C3H8) and propylene (C3H6) are important energy resources and raw materials for industrial chemistry. Today, propylene/propane separations are carried out by expensive distillation operations which are energy intensive. Therefore, there is a great interest in the development of new separation technologies like membrane modules. In this work, we collected and analyzed the data from neat polymers and mixed matrix membranes (MMM) for propylene/propane separations. Polymeric membranes are easily processed, but one important problem is plasticization since both propylene and propane are condensable gases resulting in a loss of selectivity. To improve the properties of polymer membranes, MMM were developed based on an inorganic filler and a polymer matrix to get improved performances with a synergistic effect. However, these performances strongly depend on the filler type and content, as well as their compatibility. In this review, the separation performances of neat polymers and MMM flat membranes and hollow fibers are reported. A comparison of the single gas and mixed gas permeation is presented where both permeability and selectivity are lost due to plasticization and the competitive sorption between gas molecules. Based on the results available, it can be concluded that more development can lead to improved performances for industrial-scale applications in the petroleum industries. Also, an upper bound for C3H6/C3H8 separation is proposed using neat polymers.