(496b) Solvent selection, modeling, simulation and life cycle assessment of an ionic liquid based liquid-liquid extraction process to produce lubricating base oil

Authors: 
Farahipour, R., University of Colorado Denver
Mehrkesh, A., University of Colorado Denver
Karunanithi, A. T., University of Colorado Denver

It is necessary to reduce the aromatics content of lube-oil cuts (a petroleum cut) to improve the overall quality of the produced lubricating base oil. A liquid−liquid extraction process carried out in a Rotating Disc Contactor (RDC) is usually used for aromatics removal. Furfural or sulfolane are mainly used as the solvents in this separation process because they show high selectivity towards aromatic compounds. A comparison between several conventional contactor devices shows that RDCs are the most efficient extraction systems in terms of extraction yield. Furfural is a volatile solvent which tends to escape to air when it is recovered from extract phase to be recycled to the main RDC column. Furfural has relatively high human health impacts specially when inhaled by people who work in the industrial site. Therefore, a solvent with lower vapor pressure would be preferable as replacement of such a volatile solvent. Ionic liquids (ILs) are a relatively new class of chemicals which can replace molecular compounds (e.g. solvents). Ionic liquids are made of ion pairs and the strong ionic bonding which accounts for their low vapor pressure, makes them a good alternative to replace volatile solvents. In this work we used COSMO-RS method to screen several ionic liquids which have the potential to replace volatile solvents currently used in lubricating base oil production. A simulation model which enables us to study the performance of RDC column was created. This model was used to find the energy required/raw material for the separation process with ionic liquid as the solvent. A cradle-to-gate life cycle assessment for production of 1kg lubricating base oil, was preformed based on raw materials and energy required.  The life cycle assessment was used to calculate the impacts associated with production of lubricating base oil as well as all upstream processes required. In the next step the life cycle environmental impacts of production of 1 kg lubricating base oil with ionic liquid can be compared to those in a process with a volatile solvent.