Patent GB-657496-A (GB)
Title: Improvements in or relating to the separation of mixtures of organic compounds
Filed: 1948-07-07
Abstract: In the separation of a mixture of organic compounds having a hydrocarbon radical of at least 6 carbon atoms into compounds with normal hydrocarbon chains and those with branched hydrocarbon chains by treatment with an aqueous solution of urea to form complexes including the normal compounds, a wetting agent is present, preferably of the anionic type such as alkali metal salts of organic sulphates, sulphonates, and carboxylic acids.  Examples are sodium C8-C18 alkyl sulphates, alkyl-aryl sulphonates, C9-C19 alkyl sulphonates, naphtha sulphonates, naphthenyl sulphates, and sodium oleate and palmitate.  The emulsifying properties of the wetting agent may be reduced by adding an ionizing water-soluble inorganic salt or a water-soluble salt of an organic acid of not more than 3 carbon atoms, preferably ammonium salts such as ammonium carbonate, and chromates, preferably potassium chromate, which also inhibit corrosion.  Other salts specified are ammonium chloride, sulphate, acetate, and phosphate, sodium and calcium chlorides.  Auxiliary solvents such as alcoholic or ketonic solvents may be present. The addition of preformed urea complex may be necessary to initiate reaction.  A saturated urea solution may be prepared at X DEG  C. and used at (X-40) to X-10) DEG  C., 8-12 vols. to 1 vol. of normal organic compound being suitable.  Several reactors are suitably used with concurrent flow of reactants, and peripheral speeds of the stirrer paddles of 35-40 ft./sec. in all but the last reactor where the speed is 5-10 ft./sec.  A split feed of urea solution is preferable.  The separation of mixtures of alcohols, ketones, glycols, mercaptans, esters, alkyl halides, and carboxylic acids, in addition to hydrocarbons is referred to.  In examples: (1) a C8 cracked wax distillate is treated with a saturated aqueous urea solution containing 10 per cent of methylated spirit, sodium oleate and ammonium phosphate being added.  The separated aqueous phase is heated to 45 DEG  C., giving an upper oily phase containing octene-1; (2) acetone is the auxiliary solvent; "Igepon T" (Registered Trade Mark) the wetting agent, and ammonium sulphate the salt; (3) Sodium C10 alkyl sulphate and potassium chromate are added to the urea solution; (4) a straight run naphtha is treated with aqueous urea containing isopropyl alcohol, sodium C10 secondary alkyl sulphate, and potassium chromate, with continuous temperature reduction from 10 DEG  to 0 DEG  C. and vigorous, followed by slow stirring.  The aqueous phase from the complex decomposition is recycled for treating further naphtha; (5) C9-C17 kerosene is treated, isopropyl alcohol, sodium C8-C12 alkyl sulphates, and ammonium acetate being added to the urea solution; (6) the fuel mixture is ethyl caprylate and decalin in volume ratio of 4 : 1; (7) cetyl bromide and decalin in equal volumes are treated; (8) the feed is n-heptane and decalin and the wetting agent dodecyl benzene sulphonate; (9) a C10-C18 cracked wax distillate is treated; (10) and (11) continuous treatment is effected in a series of four reactors, the reactants passing upwardly and concurrently therethrough.  Specifications 671,456, 671,457, 671,458, 671,459 and 8702/48, 8703/48, 10135/48 and 10495/48, (all as open to inspection under Sect. 91), are referred to.ALSO:In the separation of a mixture of hydrocarbons of at least 6 carbon atoms into those with normal and those with branched chains by treatment with an aqueous solution of urea to form complexes including the normal compounds, a wetting agent is present, preferably of an anionic type such as alkali metal salts of organic sulphates, sulphonates, and carboxylic acids.  Examples are sodium C8-C18 alkyl sulphates, alkyl-aryl sulphonates, C9-C19 alkyl sulphonates, naphtha sulphonates, naphthenyl sulphates, and sodium oleate and palmitate. The emulsifying properties of the wetting agent may be reduced by adding an ionizing water-soluble inorganic salt or a water-soluble salt of an organic acid of not more than 3 carbon atoms, preferably ammonium salts such as ammonium carbonate, and chromates, preferably potassium chromate which also inhibit corrosion.  Other salts specified are ammonium chloride, sulphate, acetate, and phosphate, sodium and calcium chlorides.  Auxiliary solvents such as alcoholic or ketonic solvents may be present. The addition of preformed urea complex may be necessary to initiate reaction.  A saturated urea solution may be prepared at X DEG  C. and used at (X-40) to (X-10) DEG  C., 8-12 volumes to 1 volume of normal hydrocarbon being suitable.  Several reactors are suitably used with concurrent flow of reactants, and peripheral speeds of the stirrer paddles of 35-40 feet per second in all but the last reactor where the speed is 5-10 feet per second.  A split feed of urea solution is preferable.  Cracked wax distillates, straight run naphtha, and kerosene are among the mixtures treated in the examples given.  Specifications 671,456, [Group IV (b)], 671,457, 671,458, 671,459 and 8702/48, 8703/48, 10135/48 and 10495/48 (all as open to inspection under Sect. 91), are referred to.