Granular Double Networks as a Platform for Soft, Tough, and Selective Olefin/Paraffin Separation Membranes

Ethylene is a critical building block in the chemical industry, typically produced through steam and catalytic cracking and purified from residual gases such as ethane. However, because ethylene and ethane have similar chemical structures, volatilities, and sizes, their separation involves cryogenic distillation – an energy-intensive process. Developing alternative separation methods, such as membrane-based separations, is critical for addressing this problem and mitigating the environmental footprint of the chemical sector.

In this poster, we will introduce granular double-networks as membranes for ethylene/ethane separations. These membranes consist of highly crosslinked poly(2-methoxy ethyl acrylate) microparticles embedded within a loosely crosslinked poly(2-methoxy ethyl acrylate) matrix, being composites with chemically similar but mechanically distinct phases. We will demonstrate that, when equilibrated with an ethylene carrier like silver (I) bis(trifluoromethanesulfonyl) imide salt, these membranes feature an elastic modulus of 0.3 MPa, a fracture toughness above 1000 J/m², and a permeability-selectivity trade-off that exceeds the Robeson upper bound. These results highlight the potential of the granular double-network architecture to design membranes with an optimal combination of mechanical and transport properties for low-energy separations.