Patent GB-721702-A (GB)
Title: Improvements in or relating to the recovery of naphthenic hydrocarbons
IPC: C07C7/12
Filed: 1952-06-05
Abstract: <PICT:0721702/IV (b)/1> A method for recovering naphthenes from a feed mixture containing naphthenic and non-naphthenic hydrocarbons in the gasoline and kerosene boiling range comprises flowing a first stream of the feed mixture through a bed of activated carbon under conditions to adsorb selectively the non-naphthenic hydrocarbons, then flowing a second stream of non-aromatic hydrocarbons in the gasoline and kerosene boiling range having a boiling point different from that of the feed mixture through the bed under conditions to absorb selectively said non-aromatic hydrocarbons and displace the non-naphthenic hydrocarbons from the first stream, repeating the cycle and alternately recovering from the bed a first product stream containing the naphthenic hydrocarbons from the feed mixture and non-aromatic hydrocarbons from the second stream and a second product stream containing the non-naphthenic hydrocarbons from the feed mixture and non-aromatic hydrocarbons from the second stream, and recovering naphthenic hydrocarbons from the first product stream.  A feed stock containing C6 naphthenic hydrocarbons including methyl-cyclopentane and cyclohexane, as well as paraffins in the gasoline boiling range, is withdrawn from a tank 11 and fed into an activated-carbon bed A by line 14, the paraffinic hydrocarbons being preferentially absorbed and the naphthenic hydrocarbons passing on to tank 28 by lines 25 and 27.  After a time within the range 15 minutes to 2 hours, a valve 15 is closed and the feed mixture passed to a similar bed B.  Meanwhile, a second stream is started from a tank 20, containing a paraffinic stock such as iso and normal pentanes along a line 23 to bed A.  The pentanes are selectively adsorbed and a second product stream obtained containing some pentanes and the paraffinic hydrocarbons which have been desorbed, which is directed by lines 30 and 31 to tank 32.  After a time similar to that of the flow of the feed stock a valve 24 is closed and valve 15 opened, allowing flow from tank 11 into bed A once more.  Flow from tank 11 into bed B is stopped by closing a valve 19, and flow from tank 20 started by opening a valve 34.  The first product stream from bed B, containing naphthenes is passed to tank 28 by a line 36, and a second product stream, containing pentanes and other paraffins, is passed to tank 32 by a line 38.  The first product stream in tank 28 is passed into a distillation zone 41, where the pentanes are recovered as an overhead fraction and withdrawn by line 43 and may be returned to tank 20. The C6 naphthenes are recovered through a line 44.  The second product stream in tank 32 is passed to a distillation zone 46, where the pentanes are recovered as an overhead fraction by a line 48, and the non-naphthenic hydrocarbons of the feed mixture, such as heptanes, removed by a line 49.  The absorption operation is performed at a temperature in a range of 32 DEG  to 180 DEG  F., preferably between 38 DEG  and 120 DEG  F.  The feed mixture should have a boiling range of no more than 50 DEG  F., between 100 DEG  to 400 DEG  F. The non-aromatic hydrocarbons should have a boiling range no greater than 50 DEG  F., between 85 DEG  to 550 DEG  F.  The boiling range of the non-aromatic hydrocarbons may be higher or lower than that of the feed mixture, and preferably lower.ALSO:A method for recovering naphthenes from a feed mixture containing naphthenic and nonnaphthenic hydrocarbons in the gasoline and kerosene boiling range comprises flowing a first stream of the feed mixture through a bed of activated carbon under conditions to adsorb selectively the non-naphthenic hydrocarbons, then flowing a second stream of non-aromatic hydrocarbons in the gasoline and kerosene boiling range having a boiling point different from that of the feed mixture through the bed under conditions to adsorb selectively said non-aromatic hydrocarbons and displace the non-naphthenic hydrocarbons from the first stream, repeating the cycle and alternately recovering from the bed a first product stream containing the naphthenic hydrocarbons from the feed mixture and non-aromatic hydrocarbons from the second stream, and a second product stream containing the non-naphthenic hydrocarbons from the feed mixture and non-aromatic hydrocarbons from the second stream and recovering naphthenic hydrocarbons from the first product stream.  A feed stock containing C6 naphthenic hydrocarbons including methyl-cyclopentane and cyclophexane, as well as paraffins in the gasoline boiling range, is withdrawn from a tank 11 and fed into an activated-carbon bed A by <PICT:0721702/III/1> line 14, the paraffinic hydrocarbons being preferentially adsorbed and the naphthenic hydrocarbons passing on to tank 28 by lines 25 and 27.  After a time within the range 15 minutes to 2 hours, a valve 15 is closed and the feed mixture passed to a similar bed B.  Meanwhile a second stream is started from a tank 20, containing a paraffinic stock such as iso and normal pentanes along a line 23 to bed A.  The pentanes are selectively adsorbed and a second product stream obtained, containing some pentanes and the paraffinic hydrocarbons which have been desorbed, which is directed by valve 30 and line 31 to tank 32.  After a time similar to that of the flow of the feed stock a valve 24 is closed and valve 15 opened, allowing flow from tank 11 into bed A once more. Flow from tank 11 into bed B is stopped by closing a valve 19, and flow from tank 20 started by opening a valve 34.  The first product stream from bed B, containing naphthenes is passed to tank 28 by a line 36, and a second product stream, containing pentanes and other paraffins, is passed to tank 32 by a line 38. The first product stream in tank 28 is passed into a distillation zone 41, where the pentanes are recovered as an overhead fraction and withdrawn by line 43 and may be returned to tank 20. The C6 naphthenes are recovered through a line 44.  The second product stream in tank 32 is passed to a distillation zone 46, where the pentanes are recovered as an overhead fraction by a line 48, and the non-naphthenic hydrocarbons of the feed mixture, such as heptanes, removed by a line 49.  The adsorption operation is performed at a temperature in a range of 32 DEG  to 180 DEG F., preferably between 38 DEG  and 120 DEG F.  The feed mixture should have a boiling range of no more than 50 DEG F., between 100 DEG  to 400 DEG F.  The non-aromatic hydrocarbons should have a boiling range no greater than 50 DEG F., between 85 DEG F. to 550 DEG F.  The boiling range of the non-aromatic hydrocarbons may be higher or lower than that of the feed mixture, and preferably lower.