title: Facilitated olefin transport by reversible olefin coordination to silver ions in a dry cellulose acetate membrane.
abstract: The highly selective dry complex membrane AgBF4-cellulose acetate (CA) was prepared and tested for the separation of ethylene/ethane and propylene/propane mixtures. The maximum selectivity for olefin over paraffin was found to be 280 for the ethylene/ethane mixture and 200 for the propylene/propane mixture. Solid-state interactions of AgBF4 with cellulose acetate (CA) and/or olefins have been investigated by using FT-IR, UV, and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS studies clearly show that the silver ions are coordinated by carbonyl oxygen atoms among three different types of oxygen atoms present in CA-two in the acetate group and one in the ether linkage. Upon incorporation of AgBF4 into CA, the carbonyl stretching frequency of the free cellulose acetate at 1750 cm(-1) shifts to a lower frequency by about 41 cm(-1). The binding energy corresponding to a carbonyl oxygen atom in the O 1s XPS spectrum shifts to a more positive binding energy by the incorporation of AgBF4. Reversible olefin coordination to silver ions has been observed by FT-IR and UV studies. Treatment of the AgBF4-CA membrane placed in a gas cell with propylene produces a propylene-coordinated membrane in which coordinated propylene is easily replaced by other olefins such as 1,3-butadiene.
authors.affiliation: Center for Facilitated Transport Membrane, Korea Institute of Science and Technology, Seoul.
authors.forename: J H
authors.initials: JH
authors.lastname: Ryu
authors.forename: H
authors.initials: H
authors.lastname: Lee
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: Y S
authors.initials: YS
authors.lastname: Kang
authors.forename: H S
authors.initials: HS
authors.lastname: Kim