Patent GB-682625-A (GB)
Title: Method of separating active catalyst from fatty materials by distillation
IPC: C11C3/04
Filed: 1950-07-03
Abstract: Fatty acid partial esters of polyhydric alcohols, prepared by alcoholysis of animal and vegetable oils and fats or by esterification of fatty acids, are separated from reaction mixtures containing active ester-interchange or esterification catalysts, by supplying successive small portions of the mixture to a still where it is spread in the form of a thin film and heated for a relatively short period of time in vacuum, whereby the partial ester distils without transformation to the completely esterified form, leaving the catalyst in active form in the distillation-residue.  In an example, 1 mole. of soybean oil and 2.3 moles. of glycerine are heated at 255 DEG  C. for 30 minutes in the presence of 0.1 per cent of calcium oxide.  A continuous stream of the reaction mixture is then flowed on to the rotor of an unobstructed path centrifugal still maintained under a vacuum of 5-10 microns of mercury, the rotor being heated so that the film formed thereon, is heated to about 200 DEG  C., as it passes across the rotor-surface.  The monoglycerides and unreacted glycerine are vaporized, and condensed on the condensing surface spaced from the rotor.  The yield of catalyst-free monoglycerides is more than 90 per cent of the monoglyceride-content of the reaction mixture.  The diglycerides may be removed from the distillation-residue as in the case of the monoglycerides, by suitably adjusting the temperature and pressure; or the residue, which contains the catalyst in active form, may be used as catalyst in another alcoholysis.  Fish oils, whale oil, tallow, hydrogenated tallow, wool grease, and cottonseed, coconut, palm, corn, olive, castor and peanut oils, are also referred to as starting materials. These may be reacted with methyl or ethyl alcohol, sorbitol, mannitol, trimethylene glycol, ethylene glycol, propylene glycol, polyethylene glycols, polypropylene glycols, and pentaerythritol. Catalysts referred to are: sodium hydroxide, sodium methylate, sodium carbonate, strontium oxide, calcium hydroxide, strontium hydroxide, barium oxide, alkyl sulphuric acids, aryl sulphuric acids, tetramethyl ammonium hydroxide, aluminium chloride, and boron fluoride.  The alcoholysis is preferably carried out with 200 per cent excess of the alcohol over the calculated stoichiometric proportion; and 0.01 to 0.5 mole. of catalyst per equivalent of fatty acid ester, is used. The reaction is carried out at temperatures of from 20 DEG  C. to about 400 DEG  C., depending on the materials being reacted. Specification 682,626 is referred to.ALSO:Fatty acid partial esters of polyhydric alcohols, prepared by alcoholysis of animal and vegetable oils and fats or by esterification of fatty acids, are separated from reaction mixtures containing active ester-interchange or esterification catalysts, by supplying successive small portions of the mixture to a still where it is spread in the form of a thin film and heated for a relatively short period of time in vacuum, whereby the partial ester distils without transformation to the completely esterified form, leaving the catalyst in active form in the distillation-residue.  In an example, 1 mole of soybean oil and 2.3 moles of glycerine are heated at 255 DEG C for 30 minutes in the presence of 0.1 per cent of calcium oxide.  A continuous stream of the reaction mixture is then flowed on to the rotor of an unobstructed path centrifugal still maintained under a vacuum of 5-10 microns of mercury, the rotor being heated so that the film formed thereon is heated to about 200 DEG C as it passes across the rotor-surface.  The monoglycerides and unreacted glycerine are vaporised, and condensed on the condensing surface spaced from the rotor.  The yield of catalyst-free monoglycerides is more than 90 per cent of the monoglyceride-content of the reaction mixture. The diglycerides may be removed from the distillation-residue as in the case of the monoglycerides, by suitably adjusting the temperature and pressure; or the residue, which contains the catalyst in active form, may be used as catalyst in another alcoholysis.  Specification 682,626, [Group IV(b)], is referred to.