Pervaporation separation of aromatic/aliphatic hydrocarbons by a series of ionically crosslinked poly(n-alkyl acrylate) membranes

Copolymers of methyl-, ethyl-, or n-butyl acrylate with acrylic acid were synthesized and used to fabricate ionically crosslinked, via aluminum acetylacetonate, membranes for the separation of toluene/i-octane mixtures by pervaporation at high temperatures. The effects of n-alkyl side-chain length, pervaporation temperature, and feed composition on the normalized flux and the selectivity for toluene/i-octane mixtures are determined. The relationship between chemical structure and the pervaporation properties of these polyacrylate membranes are discussed in terms of their swelling behavior. The pervaporation performance of these acrylate-based membranes is compared to other membrane materials reported in the literature. At 100 degreesC for a feed containing 50 wt. % toluene, the normalized flux of permeate increased from about 20 to over 1000 kg mum m(-2) h(-1) in going from the methyl to n-butyl acrylate, while the toluene over i-octane selectivity decreased from 13 to about 2.5. Thus, these materials provide a wide range of options within the standard productivity versus selectivity trade-off. (C) 2002 Elsevier Science B.V. All rights reserved.