Various types of multi-functional zwitterionic compounds containing both ester and sulfonate groups were prepared and their silver nitrate salts were tested as carriers for facilitated olefin transport membranes in the separation of ethylene–ethane and propylene–propane mixtures. Ester group-containing multi-functional zwitterionic silver compounds exhibited much higher performances in comparison with methyl group-containing zwitterionic compounds. A FT-IR study showed that ester-containing zwitterionic compounds interact with silver ions through both sulfonate and ester functional groups.