Patent GB-499709-A (GB)
Title: Process for recovering phenol and its homologues from petroleum oils
IPC: C07C37/00
Filed: 1938-05-16
Abstract: Phenols are extracted from petroleum distillates by (1) extracting the distillate with aqueous alkali metal hydroxide solution of 35 to 50 per cent concentration, sufficient in amount to retain the phenols in solution; (2) submitting the alkali phenolate solution to prolonged steaming preferably with saturated steam at atmospheric pressure whereby neutral oils are volatilized and sludge is precipitated; <PICT:0499709/III/1> (3) carbonating the sludge-free alkali phenolate solution to liberate the phenols, and (4) distilling the phenols rapidly in a vacuum.  A cracked petroleum distillate boiling at 180 to 230 DEG  C. passes from a tank 1 to a mixer 4 to which alkali metal phenolate solution is admitted through a line 6. The mixture passes to a settler 8 from which the upper layer of petroleum is withdrawn through a line 9.  A part of the aqueous alkali phenolate is returned together with fresh alkali hydroxide injected into a line 5, to the mixer 4, and the remainder passes to a tank 13 from which it is fed to a steaming tower 18.  Steam containing neutral oils, nitrogen bases, and sulphur compounds, passes to a condenser 21.  Precipitated sludge is withdrawn through a line 25, and the phenolate solution passes to a settler 28 where about an equal volume of water is added to deposit entrained and emulsified matter.  The clear phenolate solution is then pumped to the top of a carbonating tower 33 through which is flows downwards over baffles in countercurrent with flue gas or carbon dioxide injected through a line 34.  The liberated phenols are pumped through a heater 29 to a flash distillation tower 40 connected to a vacuum pump.  The phenol fractions may be further purified by oxidizing with air in a tower 53 at 140 to 140 DEG  C., in the presence of heavy metal sulphides.  The purified phenols are then fractionated in a tower 57.  The carbonated aqueous liquor is withdrawn from the tower and passes to a settler 37, and the aqueous layer is treated in a chamber 64 with lime whereby carbonates, naphthenates, and similar salts are precipitated.  The recovered aqueous alkali is reconcentrated in a still 69, and returns to the inlet 4.  If thiophenols are present these are preferably removed from the alkali phenolate solution before carbonating, by oxidation with air below 90 DEG  C., removing the disulphides formed, then liberating the phenols and distilling them in vacuum, and redissolving the distillate in alkali.  The disulphides are removed by centrifuging, filtering, or extraction with a solvent.ALSO:<PICT:0499709/IV/1> Phenols are extracted from petroleum distillates by (1) extracting the distillate with aqueous alkali metal hydroxide solution of 35 to 50 per cent concentration, sufficient in amount to retain the phenols in solution; (2) submitting the alkali phenolate solution to prolonged steaming preferably with saturated steam at atmospheric pressure, whereby neutral oils are volatilized and sludge is precipitated; (3) carbonating the sludge-free alkali phenolate solution to liberate the phenols; and (4) distilling the phenols rapidly in a vacuum.  A cracked petroleum distillate boiling between 180 and 230 DEG  C. passes from a tank 1 to a mixer 4 to which alkali metal phenolate solution is admitted through a line 6.  The mixture passes to a settler 8 from which the upper layer of petroleum is withdrawn through a line 9. A part of the aqueous alkaline phenolate is returned together with fresh alkali hydroxide injected into a line 5, to the mixer 4, and the remainder passes to a tank 13 from which it is fed to a steaming tower 18.  Steam containing neutral oils, nitrogen bases, and sulphur compounds passes to a condenser 21. Precipitated sludge is withdrawn through a line 25, and the phenolate solution passes to a settler 28 where about an equal volume of water is added to deposit entrained and emulsifier matter.  The clear phenolate solution is then pumped to the top of a carbonating tower 33 through which it flows downwards over baffles in countercurrent with flue gas or carbon dioxide injected through a line 34.  The liberated phenols are pumped through a heater 39 to a flash distillation tower 40 connected to a vacuum pump.  The phenol fractions may be further purified by oxidizing with air in a tower 53, at 140 to 150 DEG  C., in the presence of heavy metal sulphides. The purified phenols are then fractionated in a tower 57.  The carbonated aqueous liquor is withdrawn from the tower and passes to settler 37, and the aqueous layer is treated in a chamber 64 with lime whereby carbonates, naphthenates and similar salts are precipitated, and are separated with mineral acid.  The recovered aqueous alkali is reconcentrated in a still 69, and returns to the inlet 4.  If thiophenols are present, these are preferably removed from the alkali phenolate solution before carbonating, by oxidation with air below 90 DEG  C., removing the disulphides formed, then liberating the phenols, distilling them in vacuum, and redissolving the vacuum distillate in alkali. The disulphides formed from the thiophenols are removed by centrifuging, filtration, or extraction with a solvent.