(728g) Sorption – Selective Carbon-Molecular Sieve CMS Membranes for Same-Sized Gas Molecules Separation

In this presentation, I will describe my ongoing efforts to design membranes for the downstream separation of C₂H₄ from a mixture of CO, CO₂ following the electrochemical conversion of CO₂ to C₂H₄. To produce high purity C₂H₄, unconverted CO₂ and residual CO must be removed from the product stream. CO (d = 3.76 Å) and C₂H₄ (d = 3.75 Å) are particularly difficult to separate based on their relative diffusion coefficients; therefore, we hypothesize that a sorption-based separation mechanism could be leveraged to achieve this separation. This project intends to make metal-embedded carbon molecular sieve membranes to separate CO and C₂H₄. CMS membranes, which are pyrolyzed end-products of rigid polymers, have demonstrated precise separations for several similar-sized gas-pairs. In most cases, this separation is aided by diffusion selectivities, which in cases like CO/C₂H₄ separation, reaches a point of diminishing returns. Enhancing the sorption selectivities of these membrane materials is perceived to be a way of increasing the overall separation factors. Metals such as Cu, when incorporated within the CMS matrix, could provide the required sorption sites and when processed under optimum conditions, could facilitate higher sorption of C₂H₄ over CO, as has been demonstrated in Cu-based metal organic frameworks in prior research. A range of materials synthesized using different pyrolysis conditions and different Cu incorporation techniques will be demonstrated and the intrinsic transport parameters (sorption, permeation, diffusion) will be included as well for each condition. I will also describe some novel techniques that we are developing to characterize these metal-incorporated membranes.