Carboxylic Acids, Manufacture

Abstract

Abstract Fatty acids are produced primarily from natural fats and oils such as tallow, coconut oil, and palm oil. Tall oil fatty acids are produced by the distillation of crude tall oil. Synthetic routes to fatty acids from petroleum are an important source and include catalytic oxidation of straight‐chain hydrocarbons as carried out in Eastern Europe, Russia, and China; carboxylation and oxidation of straight‐chain 1‐olefins; and oxidation of alcohols. Branched‐chain acids are produced from branched‐chain olefins via the oxo reaction. Fatty acids are produced from natural fats and oils in essentially four steps or unit operations. Hydrolysis, the first step, is generally carried out by high temperature/pressure splitting. Glycerol is obtained as a by‐product. Second, solid or saturated fatty acids are separated from liquid or unsaturated fatty acids by solvent crystallization or by the hydrophilization process. Several newer methods of separation include adsorption and supercritical fluid extraction. The third step is hydrogenation, which converts unsaturated fatty acids into saturated fatty acids generally with the aid of a nickel catalyst. Finally, distillation is used to remove color and odor bodies and, when desired, to separate fatty acids into relatively pure materials such as lauric, myristic, palmitic, and stearic acids.