GB691684A - Improvements relating to the separation of paraffinic hydrocarbons - Google Patents

Abstract

Crude paraffin wax is separated into two paraffinic fractions having different melting points by treating it at a temperature above 0 DEG C in a water-cooled vessel with a mixture of solvent (selected from benzene and toluene) and non-solvent (selected from methanol, ethanol and butanol), the mixture containing at least sufficient non-solvent to render it azeotropic, so that only the lower melting point paraffin hydrocarbons are dissolved and separating the solution from the undissolved paraffin hydrocarbons. According to a modification of the process, the crude paraffin wax is completely dissolved in the mixture of solvent and non-solvent and the solution is then cooled to a temperature above 0 DEG C so that only the higher melting point paraffin hydrocarbons are precipitated. This cooling may be carried out stepwise, thereby producing a plurality of paraffinic fractions. The separation of the solution mentioned above or the separation of the precipitate may be carried out in a centrifuge and the solid paraffins remaining may be washed with fresh mixture of solvent and non-solvent. The mixture of solvent and non-solvent may be distilled from both solids and solution for reuse. In an example, slack wax is treated in a water-cooled vessel with a 70-30 by volume mixture of ethyl alcohol and benzene at 54 DEG F. The mixture is centrifuged and the solids washed with fresh ethyl alcohol-benzene mixture by distillation, steamblown and bleached with Fuller's earth. The refined wax has a melting point of 131-135 DEG F. The liquid phase from the centrifuge is freed of the ethyl alcohol-benzene mixture by distillation, thus leaving an oil of pour point about 50 DEG F. The Specification as open to inspection under Sect. 91 refers to the paraffin wax being dissolved in the solvent, followed by the addition of the non-solvent to precipitate the desired fraction. If desired the addition of non-solvent may be effected step-wise, while the addition of non-solvent may be accompanied by cooling. This subject-matter does not appear in the Specification as accepted.