Glycerol-based Immobilized Liquid Membranes for Olefin−Paraffin Separation

The separation of olefin−paraffin mixtures is an important and expensive operation in the petrochemical industry. Facilitated transport membranes for olefin−paraffin separation have been extensively studied in the literature in an effort to provide an economic and efficient technology for this important application. In the present work, a glycerol-based silver nitrate solution is employed for the selective separation of 1-butene over n -butane in an immobilized liquid membrane (ILM) configuration having a dry sweep gas flowing on the permeate side. The silver nitrate concentration in glycerol was studied up to 7.5 M; the 1-butene and n -butane concentrations were studied up to 10% each in the feed gas mixture. These ILMs were studied in a flat membrane substrate for their extended-term stability to variations in the feed relative humidity among other parameters. The silver nitrate−glycerol ILMs were quite stable and provided reasonable permeabilities for 1-butene with selectivities for 1-butene over n -butane as high as 850. The effective permeance of 1-butene and its selectivity increased with increasing silver nitrate concentration in the glycerol solution.