Patent GB-869299-A (GB)
Title: Separation of aromatic hydrocarbons
IPC: C10G21/08
Filed: 1957-10-16
Abstract: <FORM:0869299/IV (b)/1> A process for separating an aromatic hydrocarbon from a hydrocarbon mixture also containing hydrocarbons that are relatively more saturated than the aromatic hydrocarbon comprises adding a liquid ammonia solvent to said mixture in an extraction zone, separating an extract phase and a raffinate phase from the mixture, passing the extract phase to a distillation zone, suppling heat to the distillation zone to vaporise a portion of the extract phase, withdrawing from said distillation zone an overhead fraction relatively rich in ammonia and hydrocarbons forming an azeotropic mixture therewith, and recovering a bottoms fraction relatively rich in aromatic hydrocarbon.  In an example, a feed consisting of a virgin naphtha fraction boiling between 130 DEG  and 195 DEG F. and containing 10% of benzene was fed at the rate of 100 lbs. per hour into an extractor A to which is fed liquid ammonia at the rate of 120 lbs. per hour through a line 4, the whole being under a pressure of 240 psia.  An extract stream consisting of 83% solvent, 8,5% benzene and 8,5% non aromatic hydrocarbon is withdrawn at the top at a rate of 120 lbs. per hour and passes through pipe 2 to a distillation column B.  Open steam is introduced through line 11 at a rate of 75 lbs. per hour and at a temperature of 390 DEG F., thus producing an azeotrope containing 92% ammonia and 8% of hydrocarbon part of which is used as reflux and part returned to tower B via line 6.  The bottoms from tower B is taken to separator C where benzene is removed at the rate of about 10 lbs. per hour and at 390 DEG F. and a water layer passes to scrubber D.  The solvent is preferably pure ammonia, but small quantities of co-solvents such as methylamine or anti-solvents such as water may be added.ALSO:<PICT:0869299/III/1> A process for separating an aromatic hydrocarbon from a hydrocarbon mixture also containing hydrocarbons that are relatively more saturated than the aromatic hydrocarbon comprises adding a liquid ammonia solvent to said mixture in an extraction zone, separating an extract phase and a raffinate phase from the mixture, passing the extract phase to a distillation zone, supplying heat to the distillation zone to vaporize a portion of the extract phase, withdrawing from said distillation zone an overhead fraction relatively rich in ammonia and hydrocarbons forming an azeotropic mixture therewith, and recovering a bottoms fraction relatively rich in aromatic hydrocarbon.  In an example, a feed consisting of a virgin naphtha fraction boiling between 130 DEG  and 195 DEG F. and containing 10% of benzene was fed at the rate of 100 lbs. per hour into an extractor A to which is fed liquid ammonia at the rate of 120 lbs. per hour through a line 4, the whole being under a pressure of 240 p.s.i.a.  An extract stream consisting of 83% solvent, 8.5% benzene and 8.5% non aromatic hydrocarbon is withdrawn at the top at a rate of 120 lbs. per hour and passes through pipe 2 to a distillation column B.  Open steam is introduced through line 11 at a rate of 75 lbs. per hour and at a temperature of 390 DEG F., thus producing an azeotrope containing 92% ammonia and 8% of hydrocarbon part of which is used as reflux and part returned to tower B via line 6.  The bottoms from tower B is taken to separator C where benzene is removed at the rate of about 10 lbs. per hour and at 390 DEG F. and a water layer passes to scrubber D.  The solvent is preferably pure ammonia, but small quantities of co-solvents such as methylamine or anti-solvents such as water may be added.