Separation of Olefin/Paraffin Mixtures Using Zwitterionic Silver Complexes as Transport Carriers

Zwitterionic silver nitrate salts of 1‐(1‐methyl‐3‐imidazolio)propane‐3‐sulfonate, 1‐(1‐methyl‐1‐pyrrolidinio)propane‐3‐sulfonate, and 1‐(4‐methyl‐4‐morpholio)propane‐3‐sulfonate have been prepared and tested as carriers for facilitated olefin transport membranes in the separation of ethylene/ethane, propylene/propane, and C4 mixtures. The interactions of olefins with silver ions bound to sulfonate groups were investigated by FTIR spectroscopy as well as the correlation between the binding affinity of olefins and facilitated transport. Various imidazolium‐, pyrrolidinium‐ and morpholinium‐based zwitterionic silver complexes have been prepared and their performances as carriers for facilitated transport composite membranes investigated for selective separation of ethylene/ethane, propylene/propane, and C4 mixtures (see picture).