Pervaporative desulfurization of gasoline—separation of hydrocarbon/thiophene mixtures using polydimethylsiloxane (PDMS)-based membranes

A series of vacuum pervaporation tests were carried out to investigate the performance of the commercial composite membrane with an active layer made of polydimethylsiloxane (PDMS). The effects of feed temperature, the sulfur content in the mixture, and feed composition on membrane performance were investigated. Toluene/thiophene and n-heptane/thiophene binary organic mixtures (thiophene concentration 0.8–1.6% by mass) simulating gasoline were separated at 30–50°C, at laboratory scale. Studies have shown that the concentration of thiophene in the mixture and the temperature of the feed have a significant impact on the yield and selectivity of the desulfurization process. Experimental results indicated that higher feed temperature yielded higher total and partial fluxes and a lower sulfur enrichment factor. The total and partial fluxes increased as the sulfur content in the feed increased. The sulfur enrichment factor decreased with the amount of thiophene added in the gasoline. The experiments also showed that commercial PDMS membrane was more selective to thiophene in the case of n-haptane/thiophene mixture and it may be mainly due to higher affinity of toluene toward PDMS. The total fluxes for n-heptane/thiophene mixture and toluene/thiophene mixture were measured to be 7.4 and 9.4 kg/m² h at 40°C, with the corresponding enrichment factor values of 1.7 and 1.4, respectively.