Patent GB-344614-A (GB)
Title: Improvements in the removal of tar acids and the like from oils
IPC: C10G21/06
Filed: 1930-01-31
Abstract: Tar oils and other hydrocarbon oils are decalorized and freed from phenol and other acids by extraction with an organic base which is substantially insoluble in the oil and is of the kind obtained by interaction of an alkylene oxide and ammonia, or, as hydrochloride, by the interaction of an alkylene monochlorhydrin and ammonia. Mono-, di-, and tri-ethanolamines are specified as suitable bases. The phenol or other tar acid is recovered by diluting the extract with water, preferably followed by saturating the diluted mixture with a weakly acidic gas such as carbon dioxide or hydrogen sulphide. The free base may be recovered for re-use by concentration of the phenol-free solution.  When treating aromatic tar oils it is advisable first to mix therewith a petroleum oil to reduce the amount of aromatic hydrocarbon retained by the base.  Aromatic hydrocarbon dissolved by the base may be recovered from the extract before dilution by distillation in a current of inert gas or by extraction by a solvent.  In an example, 100 gallons of a crude low-temperature coal tar distillate boiling up to 250 DEG  C. and containing 30-40 per cent of tar acids is extracted on the counter-current principle with 66 gallons of triethanolamine.  The extract is similarly treated with its own volume of gas oil or is treated with a current of superheated steam or inert gas to recover the neutral oil retained. The oil-free extract is thrice washed with 135 gallons of water, agitation being effected by carbon dioxide or hydrogen sulphide. After separation of the phenols &c. the aqueous solution is distilled to about 160 DEG  C. to recover the acid gas and the base.  According to other examples, mixtures of equal volumes of gas oil and crude naphtha distillate from high temperature coal tar, or of equal volumes of dehydrated crude low-temperature coal tar or of its distillate boiling above 250 DEG  C. with the distillate boiling below 200 DEG  C., are treated.ALSO:Tar oils and other hydrocarbon oils are decolourized and freed from phenol and other acids by extraction with an organic base which is substantially insoluble in the oil and is of the kind obtained by interaction of an alkylene oxide and ammonia, or, as hydrochloride, by the interaction of an alkylene monochlorhydrin and ammonia.  Mono-, di-, and triethanolamines are specified as suitable bases.  The phenol or other tar acid is recovered by diluting the extract with water, preferably followed by saturating the diluted mixture with a weakly acidic gas such as carbon dioxide or hydrogen sulphide.  The free base may be recovered for re-use by concentration of the phenol-free solution.  When treating aromatic tar oils it is advisable first to mix therewith a petroleum oil to reduce the amount of aromatic hydrocarbon retained by the base.  Aromatic hydrocarbon dissolved by the base may be recovered from the extract before dilution by distillation in a current of inert gas or by extraction by a solvent. In an example, a crude low temperature coal-tar distillate boiling up to 250 DEG  C. and containing 30-40 per cent of tar acids is extracted on the counter-current principle with triethanolamine.  The extract is similarly treated with gas oil or is treated with a current of superheated steam or inert gas to recover the neutral oil retained.  The oil-free extract is washed with water, agitation being effected by carbon dioxide or hydrogen sulphide.  After separation of the phenols &c. the aqueous solution is distilled to about 160 DEG C. to recover the acid gas and the base.  According to other examples, mixtures of equal volumes of gas oil and crude naphtha distillate from high temperature coal-tar, or of equal volumes of dehydrated crude low temperature coal-tar, or of its distillate boiling above 250 DEG  C. with the distillate boiling below 200 DEG  C., are treated.