Oleochemicals hydrogenation

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]. 

Raw materials. It is possible to use any fatty acid as a feed material for sulphonation but economic considerations dictate that oleochemical material be preferred. Fatty acids are readily obtained from vegetable and animal oils and fats which are fatty acid triglycerides. These are transesterified to generate glycerol and three moles of a fatty acid ester, normally a methyl ester. The methyl ester can be distilled to give a specific cut and the fatty acid finally isolated by hydrolysis or hydrogenation of the ester. It is common to use animal fats (tallow) in which case the dominant C chains are 16 and 18. 

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. 

Fatty Amines. Fatty amines are the most important nitrogen derivatives of fatty acids. They are produced by the reaction of fatty acids with ammonia and hydrogen. They are the bases for the manufacture of quaternary ammonium compounds used as fabric softeners and biocides. Fatty amine oxides are mild to the skin with good cleaning and foaming properties and find application as a shampoo ingredient. The above mentioned products are but some of the oleochemical derivatives from coconut fatty acids (5). 

The hydrogenation of the oleochemicals can proceed in the same apparatus in which the catalyst is formed. The fatty compound is added to the catalyst solution, thus yielding a biphasic system of two immiscible liquids. After the necessary quantity of hydrogen has been introduced, an intensive stirrer mixes the two liquid phases and the gas phase. On the laboratory scale, typical hydrogenations were carried out at room temperature and at ambient pressure allowing a reaction time of about 30 min. After the reaction the two phases are separated and the solvent/ water phase is recycled with the colloid catalyst to the reactor. 

Tab. 2 Selective hydrogenation of different oleochemicals with palladium SSCs (T = 25 °C, p = 1 bar H2 solvent propene carbonate).

Palmkemel oil is more unsaturated and so can be hydrogenated to a wider range of products for the food industry, while CNO has a greater content of the more valuable shorter-chain fatty acids, which make it a little more attractive to the oleochemical industry. Some of the main food applications are given below. 

Synonyms POE (7) hydrogenated castor oil Definition PEG deriv. of hydrogenated castor oil with avg. 7 moles of EO Properties Nonionic Toxicology TSCA listed Uses Surfactant, hydrotrope, emulsifier, softener in cosmetics and pharmaceuticals Trade Name Synonyms Arlacel 989 [Uniqema] Cremophor WO 7 [BASF http //wvw.basf.com, BASF AG http //www.basf.de], Croduret 7 Special [Croda Chem. Ltd http //www.croda.co.uk, Croda Oleochems.] Dehymuls HRE 7 [Cognis/Care Chems. Cognis KGaA/Care Chems.] Emalex HC-7 [Nihon Emulsion http //www.mhon-emulsion.co.jp]... 

A variety of oleochemical feedstocks (fats and oils) can be employed to make alcohols. Coconut and palm kernel oils, however, are most often used because they produce alcohols predominantly in the lauryl (C12 and C14) range, which is considered most desirable from a performance point of view, and because they produce highly saturated alcohols which helps to minimize the degree of hydrogenation required during alcohol manufacture. 

Fatty acid esters are generally obtained from the transesterification of fats and oils with a lower alcohol, e.g. methanol, along with glycerol. More than 90% of all oleochemical reactions (conversion into fatty alcohols and fatty amines) of fatty acid esters (or acids) are carried out at the carboxy functionality. However, transformation of unsaturated fatty acid esters by reactions of the carbon-carbon double bond, such as hydrogenation, epoxidation, ozonolysis, and dimerization, are becoming increasingly of industrial importance. Here we will discuss another catalytic reaction of the carbon-carbon double bond, viz. the olefin metathesis reaction, in which olefins are converted into new products via the rupture and reformation of carbon-carbon double bonds [2]. Metathesis of unsaturated fatty acid esters provides a convenient route to various chemical products in only a few reaction steps. 

The Philippines, a major producer of coconut oil, established its first oleochemical plant of limited capacity in 1967. The plant produced only 3,000 t/yr of coco fatty alcohols. Recent data for the Philippines listed a capacity of 25,0001 of alcohol products from coconut oil by the fatty acid hydrogenation process. Philippinas Kao produced 30,0001 of alcohol products from coconut oil using the methyl ester hydrogenation process. 

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