High pressure hydrogenation, fatty

Higher molecular primary unbranched or low-branched alcohols are used not only for the synthesis of nonionic but also of anionic surfactants, like fatty alcohol sulfates or ether sulfates. These alcohols are produced by catalytic high-pressure hydrogenation of the methyl esters of fatty acids, obtained by a transesterification reaction of fats or fatty oils with methanol or by different procedures, like hydroformylation or the Alfol process, starting from petroleum chemical raw materials. 

Compared with the fatty alcohol sulfates, which are also oleochemically produced anionic surfactants, the ester sulfonates have the advantage that their raw materials are on a low and therefore cost-effective level of fat refinement. The ester sulfonates are produced directly from the fatty acid esters by sulfona-tion, whereas the fatty alcohols, which are the source materials of the fatty alcohol sulfates, have to be formed by the catalytic high-pressure hydrogenation of fatty acids esters [9]. The fatty acid esters are obtained directly from the fats and oils by transesterification of the triglycerides with alcohols [10]. 

Copper chromite catalyst, after use in high-pressure hydrogenation of fatty acids to alcohols, is pyrophoric, possibly owing to presence of some metallic copper and/or chromium. Separation of the catalyst from the product alcohols at 130°C in a non-inerted centrifuge led to a rapid exotherm and autoignition at 263°C. 

In the analysis of fatty oils complete expelling of the oxygen by a catalytic high pressure hydrogenation process reduces the problem to the analysis of saturated hydrocarbon mixtures. Such drastic chemical transformations should be executed under strongly controlled conditions only. 

To date the most common method for the production of fatty alcohols is via high-temperature and high-pressure hydrogenation of fatty methyl esters using a... 

Fatty Alcohols. Fatty alcohol is considered a basic oleochemical manufactured by high-pressure hydrogenation of fatty acids or fatty acid methyl esters. The majority of the fatty alcohol produced is further subjected to various processes, such as sulfation, ethoxylation, amination, phosphatization, sulfitation, and others. 

The fractionated methyl esters can be converted into fatty alcohols by the high-pressure hydrogenation process in the presence of a catalyst. Usually, copper chromite catalyst is used. Copper chromite catalyst also converts any unsamrated carbon double bonds so that only saturated fatty alcohols are formed. If unsamrated fatty alcohols are desired, a special zinc-bearing catalyst is employed. 

Fatty alcohols and their derivatives are important in many industrial processes where thQ are used as raw materials for surfactants and lubricants. A fot alcohol is, in general defined as a monohydric aliphatic alcohol with six or more caibon atoms. The annual production of fotty alcohols is over 1 million metric tons. Commercially fotty alcohols are produced by one of three processes the Ziegler process, the Oxo process or ly a high pressure hydrogenation of fot acids or esters. The latter process is the only one process that uses renewable natural fots/oils whereas the two first processes utilize petrochemical... 

Only a few natural sources of fatty alcohols were known at this time. Production on a technical scale could be first realized by the reduction of methyl or butyl esters of fatty acids with metallic sodium after the Bouveault-Blanc process. Nearly simultaneously, the high-pressure hydrogenation of fatty acids to the resulting alcohols was developed by Schrauth. Hence, fatty alcohols were soon available on the market in a price range that made it possible to produce fatty alcohol sulfates for use in detergents. 

The commercial manufacture of fatty alcohols started in the late 1920s. The very first natural fatty alcohol was obtained by a simple ester cleavage of oil originating in the skull of the sperm whale. But a mere 4 years later, the first industrial-scale process had already been developed for producing a fatty alcohol from coconut fatty acid by high-pressure hydrogenation. In 1958, a route was developed from fatty acid methyl ester, which still remains the most economic method of producing... 

Synthetic surfactants are usually produced in a series of strong and severe conditions such as high pressure (hydrogenation for fatty alcohol process), nitrogen protection (ethoxylation), and blended catalysts (alkyla-... 

FIGURE 12.7. High-pressure hydrogenation of fatty acid methyl esters—suspension process (13). 

Fatty acids, their methyl and butyl esters and also triglycerides are transferred to fatty alcohols by high-pressure hydrogenation. Primary feedstock is coconut or - palm kernel oil for the C12-14 range and - tallow, - palm oil and many others for the C16-18 range,... 

There are essentially four steps or unit operations in the manufacture of fatty acids from natural fats and oils (/) batch alkaline hydrolysis or continuous high pressure hydrolysis (2) separation of the fatty acids usually by a continuous solvent crystallisation process or by the hydrophilisation process (J) hydrogenation, which converts unsaturated fatty acids to saturated fatty acids and (4) distillation, which separates components by their boiling points or vapor pressures. A good review of the production of fatty acids has been given (1). 

Some more recent processes have been developed which involve direct hydrogenation of the oil to the fatty acid and 1,2-propane diol. These high-temperature (>230 °C) and high-pressure processes generally use a copper chromium oxide catalyst. 

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