Hydrolysis glycerine production

The hydrolysis is performed as a continuous countercurrent reaction in tall reaction towers (height 15-20 m, diameter 0.7 m). The reaction time amounts to 60-90 min. Reaction products are as well obtained an aqueous glycerin solution (about 15%) as on a mixture of raw fatty acids [50]. The free fatty acids are carefully distilled with the aid of a thin film evaporator (2-10 mbar, 260°C maximum) [51]. Crystallization and transwetting are additional methods for fractionation of fatty acid mixtures. 

Approximately 27% of glycerol (glycerin) comes from a synthetic process, the hydrolysis of epichlorohydrin. The remaining 73% is made from fats as a by-product of soap manufacture. 

The absence of glycerine among the products of hydrolysis in alkaline medium was also confirmed by Carlson [36]. 

This equation does not comprise the whole complex of simultaneous chemical reactions, which have already been discussed (p. 7). Later investigators (Vignon and Bay [53] Silberrad and Fanner [54], Berl and Delpy [55]) also found such products as aldehyde resins, oxalic add and ammonia. It is characteristic that from nitroglycerine hydrolysed in an alkaline medium no glycerine is recovered. Glycerine can however be obtained again when the hydrolysis is carried out in the presence... 

The hydrolysis product of ECH in neutral and acidic aqueous media is 3-chloro-l,2-propanediol and at high pH values the reaction proceeds up to the formation of glycerine (Fig. 10-14). 

Glycerin can be prepared from propylene (via ECH) or as a byproduct from fat and oil hydrolysis of the soap industry. Before 1949 all glycerin was obtained from hydrolysis of fatty triglycerides. In the past 50 years, the synthetic glycerin is to serve the portion of demand not satisfied by natural glycerin. In 1998, the U.S. production for natural versus synthetic is about 2.4 1. The diagram of different routes for the manufacture of glycerin is in Fig. 10.26. 

Glycerin by the Epichlorohydrin Process. In the ECH process, synthetic glycerin is produced in three successive operations, the end products of which are allyl chloride, ECH, and finished glycerin, respectively. Glycerin is formed by the hydrolysis of ECH with 10 percent caustic. Crude glycerin is separated from this reaction mass by multiple-effect evaporation to remove salt and most of the water. A final vacuum distillation yields a 99+ percent product. 

Splitting, or the hydrolysis of triglycerides is usually performed with high-pressure steam, resulting in the formation of split crude fatty acids and glycerin. The production of fatty acids by more sophisticated splitting processes, such as hydrolysis of fatty methyl esters, ozono lysis of unsaturated fatty acids, and chemical oxidation is practiced in special situations. 

The major use of rendered fats is in the production of tallow soaps and in the area of fat hydrolysis, sphtting triglycerides into fatty acids, and byproduct glycerine. As the soap-making industry grew and became more refined, the quality standards and specifications for animal fat became more precise to meet the soap industry s need. The specihcations and terminology, from the soap industry, form the basis for the quality standards and characteristics used today. 

Glycerine is obtained as a co-product from the hydrolysis of vegetable oils or animal fats. From the esterification of glycerine with nitric acid, the inorganic trinitrate ester (trinitroglycerine) is produced. 

Propoxylated derivatives of sorbitol are used as the polyols in the formation of rigid polyurethane foams. Sorbitol can be dehydrated and esterified with stearic acid to give sorbitol mono- or tristearate. The ester then can be ethoxylated with about 20 ethylene oxide units to give an ethoxylated surfactant. Hydrolysis of sorbitol results with glycerin, which is used in the pharmaceutical and personal care products field [108,109],... 

Oils and fats Lipases The industrial hydrolysis of fats and oils or the production of fatty acids, glycerin, poly-unsaturated fatty acids used to produce pharmaceuticals, flavors, fragrances and cosmetics... 

The same PU foam was also treated with a mixture of glycerine and water (up to 40%) to investigate the effective decomposition through the combined mechanisms of hydrolysis and glycolysis. The presence of water slowed down the process to 10 min at 160 °C, while working at higher temperatures resulted in undesired trans-esterification and pyrolysis products. However, this hydroglycolysis approach did dramatically reduce the amount of solvent required. In addition, due to the presence of water, the resultant polyols formed could be easily used in new formulations of water-blown PU foams. 

Glycidyl nitrate is formed by hydrolysis of two isomers of glycerine dinitrate. Glycerine dinitrate is hydrolyzed in 30 % KOH solution at room temperature. The oily precipitate is glycidyl nitrate with the yield of 95 %. After stability treatment, the final product can be obtained by water washing to pH 7 and drying with a desiccant. 

Since the chemistry of amphoacetates is related to a large extent to that of betaines, the by-products (apart from the amine) are almost identical. Sodium chloride is contained in a range of 6% for monoacetates, and up to 12% for diacetates. Glycolic acid, formed by hydrolysis from chloroacetic acid, is contained at 0.5-1.0% but may be as high as 4% in some grades of the surfactant. Dichloroacetic acid and residual monochloroacetic acid are found in similar concentrations as in betaines. Glycerin is not usually present, because the oil is not normally used as a raw material. However, a complete analysis of the product composition still remains to be carried out. 

Synthetic glycerin, produced by the chlorination of allyl alcohol to form dichloro-hydrin followed by hydrolysis, is the raw material in the manufacture of allyl resins and the production of nitroglycerine and other explosives. It is also used as a humectant in tobacco processing and as a plasticizer in cellophane manufacturing. 

Rate of destruction of fat by hydrolysis kpSzAh, thus giving the rate of production of glycerine as kpSzAh/w. 

Very recently, possibility for using simultaneous hydrolysis and glycolysis products of waste PET in alkyd resins manufacturing was reported. In this study, waste PET flakes obtained from grinding postconsummer bottles were treated with ethylene glycol and water in the presence of xylene, an emulsifier at 180°C and zinc acetate as catalyst. The reaction products were purified by filtration, extraction, crystallization and resins were prepared by reaction with phthalic acid, glycerine or oil fatty acid (31). 

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