GB859286A - Process for regenerating used alkaline reagents - Google Patents

Abstract

A process for the regeneration of solutions of sodium or potassium hydroxide which have been used for the treatment of liquid or gaseous organic compounds to remove acidic components therefrom, particularly a thus used aqueous solution of sodium hydroxide or potassium hydroxide, comprises subjecting the solution to an oxidising treatment by contacting with air or other free oxygen-containing gas in the presence of a catalyst comprising a metallic or metal-free phthalocyanine or a derivative thereof and thereafter separating the oxidation products of the acidic components from the solution. Specified catalysts referred to are phthalocyanines per se, a phthalocyanine containing one of the metals, Fe, Cu, Mg, Zn, Ti, Hf, Th, Su, Pb, Cm, Ta, Bi, Cr, Mo, Ni, Pd, Pt, Ag, or Hg, but preferably those containing Co, Mu, or V, or mixtures thereof. Derivatives referred to are carboxylated or sulphonated compounds of any of the above. Aqueous solutions of sodium or potassium hydroxide of 5-50% weight concentration, containing, if desired, solutizers or solubilizing agents such as methanol, ethanol, phenols, cresols or butyric acid, and containing absorbed acidic components e.g. mercaptans, from the treatment of hydrocarbon fractions e.g. sour gasolines including straight run and cracked gasoline or mixtures thereof, naphtha, jet fuel, kerosine, aromatic solvent, stove oil, range oil, burner oil, and distillate fuel oil, as well as normally gaseous hydrocarbon fractions, or from treatment of other organic materials containing acidic impurities e.g. alcohols, ketones and aldehydes, are subjected to an oxidising treatment by agitating the solution with air or other free oxygen-containing gas in the presence of the catalyst which may be present in proportions 0.0001%-20% weight of the sodium or potassium hydroxide and may be dissolved in the solution or suspended therein deposited on a suitable solid carrier e.g. charcoal, or alternatively be used in contact with the solution deposited on a carrier as a fixed bed. When the catalyst is dissolved in the solution it may remain therein during both treatments of the organic compounds to remove acidic components and regeneration, the treatment to remove acidic components however in such an instance being effected in the absence of oxygen. The oxidation may be effected at ambient temperature or above, preferably at temperatures not exceeding 95 DEG C. After oxidation the acidic impurities may be removed from the regenerated alkaline solution by skimming or liquid extraction with a suitable solvent e.g. solvent naphtha. Alternatively, the regeneration may be improved by the addition to the solution of an immiscible liquid capable of dissolving precipitated oxidised organic sulphides e.g. thio phenol, such liquid containing dissolved impurities then being removed by decantation. After oxidation the purified solution may be filtered to remove entrained solid catalyst and carrier, if present, and the regenerated solution re-used as desired.