Fractionation of triglyceride mixture

A process for separating a mixture of triglycerides with different Iodine Values and having their carboxylic acid moieties containing from 6 to 26 carbon atoms, to produce fractions of higher Iodine Value and lower Iodine Value, said process comprising the steps of

• (a) contacting a solution of said mixture in solvent with surface aluminated silica gel adsorbent to selectively adsorb triglyceride of higher Iodine Value and to leave in solution a fraction of said mixture enriched in content of triglyceride of lower Iodine Value,
• (b) removing solution of fraction enriched in content of triglyceride of lower Iodine Value from contact with adsorbent which has selectively adsorbed triglyceride of higher Iodine Value,
• (c) contacting adsorbent which has selectively adsorbed triglyceride of higher Iodine Value with solvent to cause desorption of adsorbed triglyceride and provide a solution in solvent of fraction enriched in content of triglyceride of higher Iodine Value,
• (d) removing solution of fraction enriched in content of triglyceride of higher Iodine Value from contact with adsorbent;
• said mixture of triglycerides being essentially free of impurities which can foul the adsorbent;
• the solvent in step (a) and the solvent in step (c) having the same composition or different compositions and being characterized by a solubility parameter (on a 25.degree. C. basis) ranging from about 7.0 to about 15.0, a solubility parameter dispersion component (on a 25.degree. C. basis) ranging from about 7.0 to about 9.0, a solubility parameter polar component (on a 25.degree. C. basis) ranging from about 0 to about 6.0 and a solubility parameter hydrogen bonding component (on a 25.degree. C. basis) ranging from 0 to about 11.5;
• said adsorbent being derived from silica gel having a mean pore diameter of at least about 75 angstroms and a surface area of at least about 100 square meters per gram;
• said absorbent being further characterized by a ratio of surface-silicon atoms to aluminum atoms ranging from about 3:1 to about 20:1, a moisture content less than about 10% by weight, and a particle size ranging from about 200 mesh to about 20 mesh;
• said adsorbent having cation substituents selected from the group consisting of cation substituents capable of forming .pi. complexes and cation substituents not capable of forming .pi. complexes and combinations of these;
• the solvent in step (a) and the solvent in step (c) and the ratio of surface-silicon atoms to aluminum atoms in the adsorbent and the level of cation substituents capable of forming .pi. complexes being selected to provide selectivity in step (a) and desorption in step (c).