Improvements in or relating to the extraction of sulphonic acids from acid sludge by-products of mineral oils

摘要

Sulphonic acids are extracted from acid-sludge obtained as a by-product in the refining of mineral oils with sulphuric acid or oleum by washing the sludge at a temperature of between 20 DEG and 60 DEG C. with 100 to 400 per cent by weight, relative to the sludge, of a mineral oil having a Redwood I viscosity at 100 DEG F. of between 50 and 200 seconds, and separating the wash oil containing the sulphonic acids from the sludge. If the wash oil has a viscosity-gravity constant not exceeding 0.875 and an aniline point not less than 60 DEG C., the sodium salts of the extracted sulphonic acids will have a preponderance of sodium salts preferentially soluble in hydrocarbon oil; if the wash oil has a viscosity-gravity constant not less than 0.900 and an aniline point not exceeding 50 DEG C., the sodium salts of the extracted sulphonic acids will have a preponderance of sodium salts preferentially soluble in water. The sulphonic acids may be recovered from the wash-oil by means of an aqueous alcoholic solution of an alkali such as caustic soda and the resulting sodium sulphonates may be isolated and the free sulphonic acids obtained by treatment with, e.g. sulphuric acid. The acid sludge may be prepared by reacting a naphthenic type lubricating oil distillate with 10 per cent fuming sulphuric acid at 40 DEG C. In examples: (1) sulphonic acids yielding sodium salts predominantly preferentially oil-soluble are recovered from an acid sludge using as wash oil a mineral oil distillate of viscosity-gravity constant 0.831 and aniline point 97 DEG C.; (2) sulphonic acids yielding predominantly preferentially water-soluble salts are extracted from the same acid sludge by means of an Edeleanu aromatic petroleum extract from mineral oil and having a viscosity-gravity constant of 0.909 and an aniline-point of 26 DEG C. U.S.A. Specification 1,087,888 is referred to. According to the Provisional Specification, the wash oil may be any raw or refined oil, e.g. a naphthenic base oil of viscosity 70-150 seconds at 100 DEG F.