PREPARATION OF HIGHLY BASIC CALCIUM SULFONATE

PURPOSE:To obtain a pure, highly basic calcium sulfonate with a high Ca content by passing CO2 through a mixture of an oil-soluble sulfonic acid, a hydrocarbon solvent, methanol and calcium hydroxide to carbonate the mixture, thus enabling the separation and removal of water as a by-product to be performed readily. CONSTITUTION:CO2 is passed through a mixture of an oil-soluble sulfonic acid or an alkaline earth metal salt of sulfonic acid (e.g. calcium sulfonate); an aromatic or aliphatic hydrocarbon solvent (e.g. toluene); methanol; oil; and calcium hydroxide (in an amount exceeding the theoretical amount that is needed for the neutralization of sulfonic acid) to carbonate the mixture. The amount of CO2 is 75-95wt.% of that of calcium hydroxide. Water as a by-product is absorbed into calcium oxide, and then removed. The mixed solvent in which calcium hydroxide and calcium oxide are suspended is recycled for the next preparation of a highly basic calcium sulfonate.