Patent GB-359681-A (GB)
Title: Improvements in the removal of phenols from hydrocarbons containing the same and in the recovery of pure phenols
IPC: C10G21/16
Filed: 1930-10-08
Abstract: Liquid hydrocarbons are freed from phenols by extraction with formic acid.  The solution of phenol separates as a lower layer which is removed and heated to distil over the acid for re-use. The extraction may be continuous or in one or more stages.  Acid of 50-100 per cent strength is suitable.  Acid retained by the oil or tar e.g. oil or tar boiling over 300 DEG  C. or containing aromatic constituents, may be removed by distilling off a fraction boiling up to 100-130 DEG C.; the distillate separates into a lower layer of formic acid and an upper layer of oil.  In examples (1) 100 lb. of brown coal tar are treated for several hours at ordinary temperature with 5 lb. of 77,5 per cent formic acid in a countercurrent or any known continually acting extraction apparatus.  (2) 100 lb. of coal tar middle oil containing 25 per cent of phenols and 5 per cent of pyridine bases are treated as in Example (1) with 100 lb. of 77,5 per cent formic acid.  After distilling off the acid, the mixture of phenols and pyridines is used for producing phenol phosphates or carbonates, or is directly condensed with formaldehyde or other aldehydes to form resinous masses, the pyridines acting as catalysts; when the masses are distilled to remove water the pyridines also pass over and are recovered from the distillate.  (3) 100 litres of benzine obtained by the destructive hydrogenation of brown coal low-temperature tar are treated 10 times with 10 litres each time of 77,5 per cent formic acid.  Formic acid, concentrating.--Preferably the distillation of the formic acid from the phenol is effected at 15-40 mm. absolute pressure and below 100 DEG  C. so that water present is retained by the phenols; or the major portion of acid is distilled over at low pressure, the remainder at atmospheric, the dilute acid fraction being concentrated separately by distillation under reduced pressure, preferably in presence of concentrated sulphuric acid. For continuously recovering formic acid of constant strength the phenol and acid extract may be supplied to two stills having the same condenser; the first still is operated alone until the strength of the acid passing over is below that used in the extraction, then the second still is started so that the combined vapours have the desired strength; when no more acid passes over from the first still the phenols are removed and more extract run in, the initial stronger vapours mixing with the now weaker acid vapours from the second still.ALSO:Liquid hydrocarbons are freed from phenols by extraction with formic acid.  The solution of phenol separates as a lower layer which is removed and heated to distil over the acid for re-use. The extraction may be continuous or in one or more stages.  Acid of 50-100 per cent strength is suitable.  Acid retained by the oil or tar e.g. oil or tar boiling over 300 DEG  C. or containing aromatic constituents, may be removed by distilling off a fraction boiling up to 100-130 DEG  C.; the distillate separates into a lower layer of formic acid and an upper layer of oil.  In examples: (1) 100 lb. of brown coal tar are treated for several hours at ordinary temperature with 5 lb. of 77,5 per cent formic acid in a countercurrent or any known continually acting extraction apparatus.  (2) 100 lb. of coal tar middle oil containing 25 per cent of phenols and 5 per cent of pyridine bases are treated as in example 1 with 100 lb. of 77,5 per cent formic acid.  After distilling off the acid, the mixture of phenols and pyridines is used for producing phenol phosphates or carbonates, or is directly condensed with formaldehyde or other aldehydes to form resinous masses, the pyridines acting as catalysts; when the masses are p  distilled to remove water the pyridines also pass over and are recovered from the distillate.  (3) 100 litres of benzine obtained by the destructive hydrogenation of brown coal low-temperature tar are treated 10 times with 10 litres each time of 77,5 per cent formic acid.