The silver bullet

Oeiras, 27.03.2014

Paraffin and olefin gases are produced at several stages of the petrochemical industry activity but, due to their very similar size and properties, separating one from the other is one of the most difficult, costly and energy intensive industrial processes. Thus, new energy-saving and cost-effective processes are on high demand. Researchers from the Lab of Molecular Thermodynamics have developed a new type of membranes, which use silver salts to carry olefins through the membrane, efficiently separating them from paraffins. The work, published in Journal of Materials Chemistry A (IF = 6.101), is highlighted on the journal’s front cover.

While membrane technology for paraffin/olefin separation has many advantages - including small scale of the equipment, relative environmental safety, low energy consumption and operating costs - conventional polymer membranes have poor separation performances. In alternative, facilitated transport membranes, which incorporate a carrier compound, can selectively and reversibly react with the desired gas enhancing its transport across the membrane. In this work and for the first time, polymeric ionic liquids are used to prepare improved gas separation membranes for light olefin/paraffin separation. Researchers showed that facilitated transport membranes composed of a polymeric ionic liquid incorporating different compositions of ionic liquid versus a silver salt mixture (IL-Ag⁺) can successfully be prepared and that ethane (paraffin) and ethylene (olefin) are efficiently separated. The silver salt is used as the ethylene carrier through the membrane.

Original Article

Journal of Materials Chemistry A (2014) DOI: 10.1039/C4TA00178H

Polymeric ionic liquid membranes containing IL–Ag+ for ethylene/ethane separation via olefin-facilitated transport

Liliana C. Tomé, David Mecerreyes, Carmen S. R. Freire, Luís Paulo N. Rebelo and Isabel M. Marrucho