Permeation of binuclear, sulphur containing aromatic compounds

Removal of sulphur containing aromatics from fuel is strictly regulated and thus interesting for research as well as for industrial application. Especially difficult is the removal of complex dinuclear thiophenes and their methylated derivatives with conventional hydrotreating technology. Pervaporation could be an alternative separation technology. In order to find out if the separation of the more complex aromatics is possible, especially in low concentrations, variation of separation conditions and development of suitable membrane materials is necessary. The synthesized membrane materials based on 6FDA-4MPD/DABA copolyimides were analyzed by size exclusion chromatography (SEC) and differential thermal analysis (DTA) in combination with thermogravimetric analysis (TGA). In this work temperature-dependent pervaporation experiments were carried out with benzothiophene (about 0.25 wt.%) and n-dodecane as components of a binary feed mixture. The temperature has been varied between 80 °C and 140 °C. Thereby fluxes between 4.1 kg μm m^− 2 h ^− 1 and 32 kg μm m^− 2 h ^− 1 were found. Enrichment factors up to β = 3.3 were reached. In summary, the pervaporation experiments have shown that a significant enrichment of dinuclear aromatic sulphur compounds in combination to an adequate flux is possible.