Generation of a selective layer on polyacrylonitrile membrane supports for separation of aromatic/non‐aromatic hydrocarbon mixtures by pervaporation

An application of the “pore filling” concept yielded high‐performance composite membranes for the selective pervaporation (PV) separation of aromatic/non‐aromatic hydrocarbon mixtures. Asymmetric polyacrylonitrile (PAN) membranes (average pore size of about 12 nm) were used as support for polymeric PV separation phases which were prepared in situ by heterogeneous photo‐initiated graft copolymerization. The impact of chain length of methyl polyoxyethylene (meth)acrylates and preparation parameters (UV irradiation time and degree of grafting) were analysed using PV with toluene/heptane (20/80 wt‐ratio; 80°C) as model feed. High selectivity and high permeate fluxes were achieved. Major reasons for the excellent performance were the small effective PV barrier thickness (< 5μm) and the covalent anchoring of the coated polymer.