Cuprous-chloride-modified nanoporous alumina membranes for ethylene-ethane separation

This paper reports an attempt to synthesize a CuCl-modified gamma-alumina membrane for separation. of ethylene from ethane. Cucl was effectively coated in the 4 nn pore gamma-alumina top layers of disk-shaped and tubular alumina membranes by the reservoir method. Permeation of a single gas and binary mixture of ethylene and ethane was measured to characterize separation properties of the modified membranes. Pure ethylene permeance of the CuCl-modified membrane is 10-40% lower than that predicted from the pure ethane permeance by the Knudsen theory, This result is explained by a model based on the adsorbed layer of ethylene via pi-complexation. Such an adsorbed layer hinders the diffusion of ethylene in the nanopores of CuCl-modified gamma-alumina. Multiple gas permeation measurements on the CuCl-modified membranes show a separation factor for ethylene over ethane larger than the Knudsen value. This confirms a positive contribution of the surface flow of ethylene ts the permeance of ethylene in the multiple gas permeation system. A maximum separation factor for ethylene over ethane of 1.4 is obtained for the CuCl-modified membrane at 60 degrees C.