Dynamic adsorption separation of benzene/cyclohexane mixtures on micro-mesoporous silica SBA-2

Due to benzene industrial applications, the development of selective separation methods had been taken importance. In this sense, benzene and cyclohexane separation is considered one of the most challenging isolation processes in petrochemical industry. This is due to the similarity of their structures and physicochemical characteristics, as well as the formation of an azeotrope. Recently, separation methods have been developed using porous materials as sorptive materials such as activated carbons, zeolites or ordered mesoporous silicas. In this work, SBA-2 heated at 240, 550 and 800 °C was tested as separation material using dynamic adsorption to separate benzene and cyclohexane. SBA-2 materials were characterized using powder XRD, nitrogen adsorption, TEM and 13C NMR. They were pelletized and introduced into a column to address the dynamic adsorption experiments. A dynamic adsorption system coupled to a GC-FID was built in which dynamic adsorption experiments were carried out at 50 °C using nitrogen as carrier gas at a flow-rate of 5 mL/min. The evaluation of hydrocarbons adsorption was done as single and bi-component mixture. The adsorption capacities of the three SBA-2 variants for benzene and cyclohexane using bi-component mixtures were in the range of 44–1190 and 1–20 μmol/gadsorbent, respectively. SBA-2 heated at 240 °C shows the largest adsorption capacity (1190 μmol/gadsorbent). The greatest selectivity toward benzene with SBA-2 was achieved when it was heated at 550 °C obtaining a 799.9 value. Thus, this separation can be used for the industrial separation of cyclohexane and benzene, or for the removal of benzene from gasoline.