Pervaporative removal of organosulfur compounds (OSCs) from gasoline using PEBA and PDMS based commercial hydrophobic membranes

Vacuum pervaporation experiments were conducted to recognize the efficiency of organosulfur compounds (OSCs) separation from gasoline using commercial hydrophobic membranes. Three of typically presented in gasoline sulfur species, i.e. thiophene, 2-methylthiophene and 2,5-dimethylthiophene, were selected to investigate the different sulfur compounds removal efficiency from n-octane/sulfur species used as a model gasoline. The influence of process parameters such as feed temperature, feed concentration on OSCs removal from model n-octane/sulfur compound mixtures was also examined. During the test, the commercial hydrophobic PEBA-based and PDMS-based composite membranes were applied. Conducted experiments with chosen sulfur species confirmed that the structure of a component and the resulting differences in the affinity toward tested membrane and physico-chemical properties can influence the membrane performance and led to different separation efficiency. Total fluxes for n-octane/thiophene, n-octane/2-methylthiophene and octane/2,5-dimethylhiophene mixtures at 30 °C were equal to be 1.33, 1.42 and 1.29 kg/m² h in case of PEBA membrane and 7.21, 7.48 and 7.34 kg/m² h for PDMS-base membrane, with the corresponding separation factor β values of 7.04, 3.95 and 1.25 for PEBA and 2.95, 1.56 and 1.01 for PDMS, respectively. The intrinsic selectivity for tiophene/n-octane mixture (α_T/O) also indicated that PEBA membrane (α_T/O ≈ 18) is much more selective than PDMS one (α_T/O ≈ 7.5).