Sharing five years of pilot plant experience on aromatics extraction with ionic liquids

Since 2004 pilot plant trials have been conducted with various contactors and different ionic liquids for petrochemical model feeds as well as real refinery feeds. Our pilot plant contains several columns (rotating disc contactor, Kuhni, pulsed disc and donut column) with a height of 6 m and 5 cm diameter. Up to 100 kg of ionic liquid and 200 L of feed are applied in experiments. In this paper the hydrodynamic and mass transfer performance of a rotating disc contactor has been characterised for toluene/heptane, a model FCC (fluid catalytic cracker) feed and a real LCCS (Light Catalytically Cracked Spirit) refinery feed using 3-methyl-N-butyl-pyridinum dicyanamide as the ionic liquid. Experiments with the real LCCS feed demonstrated comparable extraction performance to the model FCC feed. Over the past five years the same batches of ionic liquids have been repeatedly regenerated by evaporation and reused. The studies revealed that, although coloration occurs, the extraction performance of the ionic liquids has not changed even after several years of usage. After the real LCCS refinery feed experiments, validation with the toluene/heptane model feed confirmed unchanged extraction performance.