REACTIVE POLYMER MEMBRANES FOR ETHYLENE ETHANE SEPARATION/

Olefin/paraffin separations by distillation are highly energy intensiv e, Facilitated transport, or reactive membranes have long been investi gated as an alternative and/or complementary separation technology to conventional distillation, However, stability problems associated with facilitated transport membranes have been the primary obstacle in the development of commercial FT processes. In this paper, we report the development of a polymer membrane containing silver(I) ion that facili tates the transport of ethylene in the absence of solvent. Blends of i onically conductive and electrically conductive polymers were found to have the appropriate electronic environment to allow reaction of silv er(I) ion and ethylene. The results for the ethylene/ethane separation were obtained with composite membranes of silver(I)-form Nafion(R) an d 2 wt% poly(pyrrole). Permeation measurements were performed with eth ylene/ethane mixtures at total feed pressures ranging from 760 to 1900 mmHg and at temperatures of 40 degrees C to 70 degrees C, Pure gas pe rmeability measurements were obtained at a total feed pressure of 1900 mmHg and temperatures of 30 degrees C and 40 degrees C. Ethylene/etha ne separation factors with the silver(I)-form Nafion-poly(pyrrole) com posite membranes increased from 8 to 15 as temperature decreased. Ethy lene permeabilities increased from 0.2 to 1 Barrer over the temperatur e range of 30 degrees C to 70 degrees C:. An ethylene/ethane mixed gas permeability ratio of about 2 was observed with non-reactive proton-f orm Nafion-poly(pyrrole) composite membranes, Ethylene permeation meas urements as a function of membrane thickness suggested that the facili tated transport of ethylene approached the reaction-limited regime at membrane thickness of 5 mu m. The complexation between ethylene molecu les and silver(I) ions in Nafion-poly(pyrrole) composite membrane was observed with FTIR spectroscopy.