649. FETTERLY, L. C. (N. V. de Bataafsche Petroleum Maatschappij). [Extractive Crystallization of Hydrocarbons From Their Mixtures With Urea by formation of Crystalline Complexes.] French Patent 963,978. July 26, 1950: appl. filed Mar. 30. 1948. Chem.

Patent Abstracts

649. FETTERLY, L. C. (N. V. de Bataafsche Petroleum Maatschappij). [Extractive Crystallization of Hydrocarbons From Their Mixtures With Urea by formation of Crystalline Complexes.] French Patent 963,978. July 26, 1950: appl. filed Mar. 30. 1948. Chem. Zentralb., 1951. I, p. 2382.

Straight-chain hydrocarbons form crystalline complex compounds, whereas the hydrocarbons with branch chains, especially isoparaffins as well as aromatic and naphthenic hydrocarbons, remain unchanged. The process consists in treating the hydrocarbon mixture with aqueous or alcoholic saturated solutions of urea. The crystalline complex formation and separation is especially influenced by the temperature, for example, the quantity of hydrocarbons tending toward the formation of complexes is increased with decrease in temperature. In most cases the operation is carried on between 20º-0º. Through temperature regulation crystalline fractions separate, which contain hydrocarbons of different molecular weights; for example, at temperatures >30º only straight-chain hydrocarbons with at least 6 C atoms form crystalline complexes. Therefore, it is easy to separate the straight-chain gaseous hydrocarbons from the higher molecular paraffin hydrocarbons.