EP0000916B1 - Process for the production of fatty acid nitriles and glycerine from glycerides, in particular from natural fats and/or oils - Google Patents

Description

worin R_1' R₂ und R₃, die gleich oder verschieden sein können, aliphatische Kohlenwasserstoffreste mit 3 bis 23 Kohlenstoffatomen bedeuten, wobei diese Reste gegebenenfalls mit einer OH-Gruppe substituiert sein können, oder von Gemischen solcher Glyceride in flüssiger Phase mit Ammoniak unter Gewinnung von Fettsäurenitrilen der Formel R₃ (R₁, R₂)-CN und von Glycerin mittels Hindurchleiten von gasförmigem Ammoniak, gegebenenfalls unter Zumischung von Inertgas, bei erhöhten Temperaturen und in Gegenwart von Katalysatoren.The invention relates to a process for reacting mono-, di- and triglycerides of the general formula

wherein R _{1 '} R ₂ and R ₃ , which may be the same or different, mean aliphatic hydrocarbon radicals having 3 to 23 carbon atoms, which radicals may optionally be substituted by an OH group, or mixtures of such glycerides in the liquid phase with ammonia Obtaining fatty acid nitriles of the formula R ₃ (R ₁ , R ₂ ) -CN and glycerol by passing gaseous ammonia, optionally with the addition of inert gas, at elevated temperatures and in the presence of catalysts.

Fatty acid nitriles, which are important intermediates for the production of amines, are preferably produced by technical processes from the corresponding fatty acids and ammonia in the presence of suitable catalysts. This synthesis, which has been known for a long time, can be carried out both in the liquid phase in a temperature range from 250 to 350 ° C. and in the gas phase in a temperature range from 320 to 380 ° C. Suitable catalysts for the reaction in the liquid phase are e.g. Zinc oxide or manganese acetate, for the gas phase for example aluminum oxide or bleaching earth. Summary information on such processes can be found in "Methods of Organic Chemistry" (Houben-Weyl), Volume 8, page 330 ff., Georg Thieme Verlag, Stuttgart, 1952, and in "Fatty Acids and their Industrial Applications", Marcel Dekker, New York, 1968, page 909 ff. A process for the production of fatty acid nitriles by reacting fatty acids with ammonia in the liquid phase in the presence of zinc or calcium salts of fatty acids is described in US Pat. No. 2,589,232. Another process in which titanium acid esters are short-chain Aliphatic alcohols are used as catalysts and, in addition to fatty acids, the fatty acid esters of short-chain alcohols can also be used as starting products, is described in US Pat. No. 2,993,926. If natural fats or oils are to be used for the processes mentioned, the first step is to obtain the free ones Fatty acid or the short-chain fatty acid ester in a separate stage.

It is also known to convert natural fats or fatty acid esters of monohydric alcohols to the corresponding fatty acid amides by reaction with ammonia. Suitable catalysts for this are, for example, metal oxides or calcium nitrate (cf. Japanese patent publications 70-35524 and 71-21846 and 71-6614). The fatty acid nitrile can then be obtained in a known manner from the fatty acid amides by dehydration in a second stage.

A process is known from Japanese Patent Publication 72-26921 in which natural fats can be converted into fatty acid amides by reaction with aliphatic amines. wherein the resulting glycerol is removed from the equilibrium by the presence of boric acid as the glycerol boric acid ester.

From an economic point of view, a process would be desirable in which natural fats or oils, i.e. native triglycerides, which can contain small amounts of mono- and diglycerides, without isolating the fatty acid amide stage or without the detour via the free fatty acid or the short-chain fatty acid ester directly in the corresponding fatty acid nitriles can be transferred.

Such attempts have already been made. GB-A 416 613 and 451 594 describe a process for the reaction of hydroxy fatty acids or fatty acids, obtained from natural fats, with ammonia to give fatty acid nitriles in the gas phase at temperatures of 300 to 450 ° C. in the presence of oxidic dehydration catalysts, in particular in the presence of alumina. There are also indications that glycerides can be used directly, although they cannot be evaporated under the specified conditions. Examples 3 of GB-A 416 631 and Examples 7 and 14 of GB-A 451 594 show such reactions of castor oil, palm kernel fat and coconut oil with ammonia at temperatures from 350 to 400 ° C. in the presence of bauxite. However, there is no evidence of the whereabouts of glycerol. Refinements have shown that the glycerol is completely decomposed by thermal cleavage under the conditions of this process.

This not only leads to the loss of a valuable raw material, but also causes a decisive deterioration in the quality of the fatty acid nitriles obtained as products, which is manifested in particular in the color and smell. Since fatty acid nitriles are intermediate products and high levels of purity are required for further processing, this makes complex cleaning operations necessary to remove the decomposition products, as a result of which the process mentioned is completely uneconomical.

From GB-A 477 463 a method is known by which the conversion of fatty acids Nitriles in the liquid phase should preferably be carried out without catalysts. It is claimed that when glycerides are used as the starting material, glycerol can also be obtained. However, an experimental check shows that only the slightest traces of glycerin are formed in addition to a high amount of decomposition products of the glycerol, the latter contaminating the nitrile formed. The use of cobalt salts of fatty acids for converting free fatty acids into nitriles is known from US Pat. No. 2,493,637. French patent 864 571 mentions, among other things, the carboxylic acid salts of heavy metals for the conversion of adipic acid amide with acetic anhydride to adiponitrile as catalysts.

The task was therefore to develop a one-step process by which it is possible to obtain glycerol in high yield in addition to the fatty acid nitrile from glycerides in economically justifiable reaction times.

worin R_j, R₂ und R₃, die gleich oder verschieden sein können, gesättigte oder ein- oder mehrfach ungesättigte Kohlenwasserstoffreste mit 3 bis 23 Kohlenstoffatomen bedeuten, wobei diese Reste gegebenenfalls mit einer OH-Gruppe substituiert sein können, oder Gemischen solcher Glyceride in flüssiger Phase mit Ammoniak unter Gewinnung von Fettsäurenitrilen der Formel R₃ (R,, R₃)-CN und von Glycerin mittels Hindurchleiten von gasförmigem Ammoniak, gegebenenfalls unter Zumischung von Inertgas, bei erhöhten Temperaturen und in Gegenwart von Katalysatoren, das durch gekennzeichnet ist, daß das Glycerid mit einem Ammoniakstrom von mindestens 200 I/kg Glycerid und Stunde, bei Temperaturen von 220 bis 300°C, in Gegenwart von Blei-, Zink-, Cadmium-, Zinn-, Titan-, Zirkon-, Chrom-, Antimon-, Mangan-, Eisen-, Nickel- oder Kobaltsalzen von Carbonsäuren oder Sulfonsäuren als Katalysatoren in innigen Kontakt gebracht, das erhaltene Produktgemisch unter rascher Entfernung des gebildeten Glycerins aus der Reaktionszone ausgetragen und das ausgetragene Produktgemisch einer Phasentrennung in eine Fettsäurenitrilphase und eine Glycerin/Wasser-Phase unterworfen wird.The object is achieved in the sense of the invention by a process for the implementation of mono-, di- and triglycerides of the general formula

wherein R _j , R ₂ and R ₃ , which may be the same or different, are saturated or mono- or polyunsaturated hydrocarbon radicals having 3 to 23 carbon atoms, which radicals can optionally be substituted by an OH group, or mixtures of such glycerides in liquid phase with ammonia to obtain fatty acid nitriles of the formula R ₃ (R ,, R ₃ ) -CN and glycerol by passing gaseous ammonia, optionally with admixture of inert gas, at elevated temperatures and in the presence of catalysts, which is characterized by that the glyceride with an ammonia stream of at least 200 I / kg glyceride and hour, at temperatures of 220 to 300 ° C, in the presence of lead, zinc, cadmium, tin, titanium, zirconium, chromium, antimony -, Manganese, iron, nickel or cobalt salts of carboxylic acids or sulfonic acids as catalysts brought into intimate contact, the product mixture obtained with rapid removal of the glyceri formed ns discharged from the reaction zone and the discharged product mixture is subjected to a phase separation into a fatty acid nitrile phase and a glycerol / water phase.

das heißt, in dieser Formel können ein oder zwei Fettsäurereste durch H ersetzt sein. Die Fettsäurereste R₁CO-, R_zCO- und R₃C0- leiten sich ab von Fettsäuren mit 3 bis 23 Kohlenstoffatomen. Die aliphatischen Kohlenwasserstoffreste R,, R₂ und R₃ können geradkettig oder auch ein- oder mehrfach verzweigt sein. Sie können gesättigte Ketten darstellen oder auch eine oder mehrere Mehrfachbindungen, vorzugsweise Doppelbindungen, aufweisen. Gegebenenfalls können diese Reste mit einer OH-Gruppe substituiert sein. Bevorzugte Ausgangsstoffe für das erfindungsgemäße Verfahren sind vor allem die natürlichen Fette, die Gemische aus überwiegend Triglyceriden und kleinen Anteilen aus Diglyceriden und Monoglyceriden darstellen, wobei auch diese meist wiederum Gemische darstellen und verschiedenartige Fettsäurereste im obengenannten Bereich, insbesondere solche mit 8 und mehr C-Atomen, enthalten. Beispielsweise seien genannt pflanzliche Fette, wie Olivenöl, Cocosfett, Palmkernfett, Babussuöl, Palmöl, Erdnußöl, Rüböl, Rizinusöl, Sesamöl, Cottonöl, Sonnenblumenöl, Sojaöl, Hanföl, Mohnöl, Avocadoöl, Baumwollsaatöl, Weizenkeimöl, Maiskeimöl, Kürbiskernöl, Traubenkernöl, Kakaobutter oder Pflanzentalge, ferner tierische Fette, wie Rindertalg, Schweinefett, Knockenfett, Hammeltalg, Japantalg, Walöl und andere Fischöle sowie Lebertran. Ebenso eingesetzt werden können aber auch einheitliche Tri-, Di- und Monoglyceride, sei es, daß diese aus natürlichen Fetten isoliert oder auf synthetischem Wege gewonnen wurden. Hier seien beispielsweise genannt: Tributyrin, Tricapronin, Tricaprylin, Tricaprinin, Trilaurin, Trimyristin, Tripalmitin, Tristearin, Triolein, Trielaidin, Trilinoliin, Trilinolenin, Monopalmitin, Monostearin, Monoolein, Monocaprinin, Monolaurin, Monomyristin oder gemischte Glyceride wie beispeilsweise Palmitodistearin, Distearoolein, Dipalmitoolein oder Myristopalmitostearin.The starting materials for the process according to the invention are mono-, di- and triglycerides of the general formula

that is, in this formula, one or two fatty acid residues can be replaced by H. The fatty acid residues R ₁ CO-, R _z CO- and R ₃ C0- are derived from fatty acids with 3 to 23 carbon atoms. The aliphatic hydrocarbon radicals R ₁ , R ₂ and R ₃ can be straight-chain or can be branched one or more times. They can represent saturated chains or can also have one or more multiple bonds, preferably double bonds. If appropriate, these radicals can be substituted with an OH group. Preferred starting materials for the process according to the invention are, above all, natural fats, which are mixtures of predominantly triglycerides and small proportions of diglycerides and monoglycerides, these also mostly representing mixtures and various types of fatty acid residues in the abovementioned range, in particular those with 8 or more carbon atoms , contain. Examples include vegetable fats, such as olive oil, coconut fat, palm kernel fat, babussu oil, palm oil, peanut oil, rapeseed oil, castor oil, sesame oil, cotton oil, sunflower oil, soybean oil, hemp oil, poppy oil, avocado oil, cottonseed oil, wheat germ oil, corn oil, pumpkin seed oil, vegetable oil, grape seed oil, grape seed oil , also animal fats, such as beef tallow, pork fat, knock fat, mutton tallow, Japanese tallow, whale oil and other fish oils and cod liver oil. Uniform tri-, di- and monoglycerides can also be used, be it that they have been isolated from natural fats or obtained synthetically. Examples include: tributyrin, tricapronin, tricaprylin, tricaprinin, trilaurin, trimyristin, tripalmitin, tristearin, triolein, trielaidin, trilinoliin, trilinolenin, monopalmitin, monostearin, monoolein, monocaprinin, monolaurinoloin, monoleurinoloin, monoleurinoloin, monoleurinolein, monoleurinoleininolomine, monoleininoleininomein, monoleinininolein, monoleinineinolein, monoleinininolein, monoleinininolein, monoleinininolein, monoleininoleininolein, monoleinineinolein, monoleinininoleinineinomein, monoleinininoleinineinomein, monoleurinoleinineinomein, monoleinininoleinineinomein, monoleurinoleinininomein, as well as, or myristopalmitostearin.

Three process parameters are decisive for the success of the one-step process, i.e. the extraction of fatty acid nitrile or a mixture of fatty acid nitriles in high purity and high yield as well as the production of glycerin in high yield, namely the choice of the correct temperature or the correct one Temperature control, the rapid removal of the formed Glycerin from the reaction zone and the selection of the right catalyst.

The rapid removal of the glycerol from the reaction zone means that a certain minimum amount of ammonia is passed through the reaction mixture. This is at least 200 per kg glyceride and hour, preferably at least 400 per kg glyceride and hour. There is no upper critical limit with regard to the ammonia flow to be passed, the quantitative upper limit is determined at best by economic considerations and is for this reason about 1000 preferably about 800 ammonia per kg glyceride and hour. Up to 30%, preferably up to 15%, based on the amount of ammonia passed through, of inert gas, for example nitrogen, can advantageously be added to the amount of gas passed through.

Furthermore, it is of crucial importance that the reaction temperature is kept in the range between 220 and 300 ° C., preferably 230 to 290 ° C., during the entire course of the reaction. The temperature is preferably allowed to rise from the beginning to the end of the process. This can be done continuously or in stages, in particular in the form of a temperature program. A preferred temperature program is that the reaction initially takes place in the temperature range from about 220 to 240 ° C. until about 30 to 70% of the theoretically expected amount of glycerol has been discharged from the reaction vessel, that the temperature is then raised in the course of about half to Gradually or continuously increased for 5 hours until a temperature range of about 270 to 400 ° C. is reached, and the reaction then ends in this temperature range. The end of the reaction can be recognized from the fact that no more liquid phase passes into the receiver.

• Offenkettige Carbonsäuren mit gerader oder verzweigter Kette, wobei diese Kette gesättigt ist oder auch eine oder mehrere Doppelbindungen enthalten kann und 4 bis 23, vorzugsweise 8 bis 23 Kohlenstoffatome besitzt,

Finally, the selection of the catalysts is of essential importance for the process according to the invention. The lead, zinc, cadmium, tin, titanium, zirconium, chromium, antimony, manganese, iron, nickel or cobalt salts of organic carbon or sulfonic acids can be used as catalysts. The catalysts mentioned can also be used in the form of mixtures. The organic carboxylic and sulfonic acids from which the anions of the salts mentioned are derived belong in particular to the following groups:

• Open-chain carboxylic acids with a straight or branched chain, which chain is saturated or can also contain one or more double bonds and has 4 to 23, preferably 8 to 23, carbon atoms,

Alkylcarboxylic acids, preferably alkylbenzenecarboxylic acids and alkylnaphthalenecarboxylic acids, which carry one or more alkyl radicals each having 1 to 23, preferably 1 to 12, carbon atoms,

Alkyl sulfonic acids and alkyl disulfonic acids with straight-chain or branched alkyl radicals having 4 to 24, preferably 8 to 24 carbon atoms, where these alkyl radicals can be substituted, if appropriate, with OH groups, preferably with an OH group, and furthermore partially or preferably completely in the alkyl chain can be replaced by fluorine, and also alkylarylsulfonic acids, in particular alkylbenzenesulfonic acids and alkylnaphthalenesulfonic acids (each of which is understood to mean the mono-, di- and trisulfonic acids), with one or more straight-chain or branched alkyl radicals each having 1 to 24 carbon atoms, the alkyl chains mentioned also having two, preferably substituted with a carboxyl group.

• n-Dodecylsulfonsäure, n-Octadecylsulfonsäure, lsobutylnaphthalinsulfonsäure, n-Butylnaphthalinsulfonsäure, Isopropylnaphthalinsulfonsäure, Cetylbenzolsulfonsäure, Octadecylbenzolsulfonsäure, Tetrapropylenbenzolsulfonsäure und Triisobutylbenzolsulfonsäure.

Of these salts which can be used as catalysts in the process according to the invention, the lead, cadmium, iron, cobalt and in particular the zinc salts are particularly preferred with regard to the cation. With regard to the anion, the above-mentioned groups of sulfonic acids are particularly preferred, but in particular the alkylarylsulfonic acids of the latter group are derived therefrom. Examples include:

• n-dodecylsulfonic acid, n-octadecylsulfonic acid, isobutylnaphthalenesulfonic acid, n-butylnaphthalenesulfonic acid, isopropylnaphthalenesulfonic acid, cetylbenzenesulfonic acid, octadecylbenzenesulfonic acid, tetrapropylenebenzenesulfonic acid and triisobutylbenzenesulfonic acid.

The salts used as catalysts in the process according to the invention can be obtained by reacting the free acids with the corresponding metal oxides by known processes. The free sulfonic acids can be obtained from the known sulfonation processes or from the corresponding alkali sulfonates, for example via ion exchangers.

The catalysts mentioned can be added directly in the form of the salts mentioned. However, the corresponding metal oxide and the corresponding carbon or sulfonic acid can also be added individually to the reaction mixture, the catalyst forming in situ during the reaction. The catalysts mentioned are used in the process according to the invention in amounts of from 0.5 to 75% by weight, in the case of batchwise operation preferably from 1 to 25% by weight and in particular from 1 to 10% by weight, in the case of continuous operation in amounts of preferably 5 to 75% by weight, in particular 10 to 30% by weight, based in each case on the glyceride used, is added.

To carry out the process according to the invention, the respective glyceride or glyceride mixture is placed in a suitable reaction vessel, for example a stirred kettle, together with the catalyst described above. The total amount of catalyst or a partial amount can be initially introduced, the remaining part then being added in portions or continuously during the reaction. The reaction vessel is equipped with a gas inlet device that allows the gas flow to be measured. provided, further with a temperature measuring device, a Heating device and if necessary with a stirrer. The reaction vessel is connected to a condensation device which consists of one or preferably a plurality of condensation tanks heated to temperatures of about 60 ° to 120 ° C. After the reaction vessel has been heated, which is optionally carried out with a nitrogen purge, the ammonia stream is set after the initial temperature has been reached. The product mixture emerging into the condensation device consists in the initial phase of higher proportions of crude glycerol. The proportion of fatty acid nitrile increases more and more in the course of the reaction, so that essentially pure fatty acid nitrile is discharged in the last part, while the discharge of the crude glycerol has already ended. The ammonia stream (to which inert gas can be added, as described above) also ensures that the water of reaction is discharged rapidly over the entire duration of the reaction. The escaping gas stream is expediently returned to the reaction after the water carried off has been separated off and, if appropriate, with the addition of fresh ammonia. The product mixture discharged collects in the condensation device, this mixture being pre-separated into a fatty acid nitrile phase and a crude glycerol / water phase. The final phase separation is expediently carried out after the condensation device has been drained and transferred to a separator, for example a steam separator, at about 60 to 100.degree. Residual glycerin is washed out of the fatty acid nitrile phase with water. The crude glycerol isolated from the aqueous phase (for example by distillation) can be purified by known processes (cf. UIImann Encyklopadie der Technischen Chemie, 1956, Volume 7, pages 523 to 524), for example by distillation.

The process according to the invention makes it possible to produce fatty acid nitriles and glycerol in excellent yields. These yields are at least 93% and reach 96% and more fatty acid nitrile and up to 95% crude glycerol (in each case based on the theoretical yield based on the glyceride used). The fatty acid nitrile obtained contains at most up to 2% by weight of free fatty acids and up to 10% by weight, but usually less than 6% by weight of fatty acid amides as by-products.

These fatty acids and fatty acid amides contained in the discharged product mixture are also expediently also converted into fatty acid nitriles by subjecting them to a post-reaction in the presence of ammonia and in the presence of the catalysts defined above, if appropriate before the phase separation.

• Nach einer bevorzugten Methode wird zwischen den Reaktor und die Kondensationsvorrichtung eine Fraktionierkolonne zwischengeschaltet. Diese Fraktionierkolonne, die eine Spiegelglaskolonne oder ein gut isoliertes Rohr, gefüllt beispielsweise mit Raschigringen, sein kann, trennt die während der Reaktion intermediär gebildeten Fettsäureamide und freien Fettsäuren ab und führt sie in das Reaktionsgefäß zurück, während das restliche ausgetragene Produktgemisch in die Vorlage gelangt und dort unter Kondensation gesammelt wird wie oben beschrieben.

This after-reaction can either be subjected to the free fatty acids and fatty acid amides separated from the discharged fatty acid nitrile, optionally together with crude nitrile which has not yet been discharged, or the entire fatty acid nitrile phase is post-treated. This can be done in particular according to the following embodiments of the after-reaction:

• According to a preferred method, a fractionation column is interposed between the reactor and the condensation device. This fractionation column, which can be a mirror glass column or a well-insulated tube filled with, for example, Raschig rings, separates the fatty acid amides and free fatty acids formed during the reaction and returns them to the reaction vessel, while the remaining discharged product mixture gets into the receiver and is collected there under condensation as described above.

With the interposition of this fractionation system, the method according to the invention can be designed to be fully continuous in a particularly simple manner. For this purpose, the glyceride, as described above, is placed in the reaction vessel together with the previously mentioned proportions of catalyst or, optionally, added to an inert, non-volatile solvent, such as paraffin oil. The amount of ammonia added should also be at least 2001 / kg glyceride and hour and is normally at higher throughputs than those specified above for the batchwise procedure.

The process temperatures should advantageously be kept in the temperature range from 220 to 270 ° C., in particular in the temperature range from 230 to 250 ° C. The glyceride is then continuously replenished during the reaction.

Glyceride and catalyst can also be fed continuously in a mixture. The fractionation system continuously discharges fatty acid nitrile, glycerol and water, while fatty acid amide and free fatty acid are continuously returned to the process.

According to a further variant of the aftertreatment, the reaction is first carried out until the crude glycerol is essentially completely discharged (which can be seen in the phase separation since the crude glycerol phase no longer increases), and then the fatty acid nitrile phase obtained from the phase separation does not become that yet The portion of fatty acid nitrile discharged is returned to the reactor, the temperature in the reactor being set to a range from 200 ° to 320 ° C. and the ammonia stream to an amount of 5 to 150 I / kg fatty acid nitrile and hour, preferably to 15 to 100 I / kg, is reduced. If sufficient catalyst has already been used in the first part of the reaction (catalyst amounts which are at the upper limit of the quantitative ranges mentioned above), the additional addition of catalyst is unnecessary. Otherwise, a corresponding amount of catalyst has to be added. Under these reaction conditions, the complete conversion of fatty acid mides and fatty acids into fatty acid nitriles takes place, which can be followed by the formation of water of reaction. This water comes with the excess ammonia discharged, the ammonia stream, optionally with the addition of fresh ammonia and after removal of water, can be returned to the process. After the reaction has ended, the fatty acid nitrile present in the reactor is expediently subjected to a distillation in order to remove the catalyst.

According to a further method, however, the entire fatty acid nitrile can also be discharged from the reaction, subjected to the phase separation and then introduced into a second reactor (post-reactor), the above-mentioned catalysts being added in the amounts mentioned. The aftertreatment then takes place under the same conditions as those mentioned above for the return of a partial amount to the first reaction vessel. Here, too, the fatty acid nitrile has to be worked up by distillation after the after-treatment has ended.

This aftertreatment method can also be modified such that the entire fatty acid nitrile phase is carried out continuously, for example through a tubular reactor, under the specified conditions.

Finally, the fatty acid nitrile phase obtained can also be in the gaseous state together with ammonia in an amount of 200 to 800 I / kg fatty acid nitrile and hour, preferably 300 to 600 I / kg, and at a temperature of 280 to 400 ° C, preferably at 300 to 380 ° C, continuously passed over a fixed bed of dehydration catalysts. Suitable dehydration catalysts are, for example, aluminum oxide in the form of bauxite or hydrargilite, thorium oxide, zirconium oxide, aluminum phosphate, silica gel, active bleaching earth and the like or mixtures thereof.

The process according to the invention therefore surprisingly makes it possible not only to obtain fatty acid nitriles in excellent yields and good purity, but also to obtain glycerol in high yields. With the post-treatment methods described, the purity of the fatty acid nitrile obtained can be increased further, so that it is less than 2% by weight, in most cases less than 0.1% by weight of fatty acid amide and less than 1.5% by weight, in most cases contains less than 0.1% by weight of free fatty acids and is otherwise completely free of by-products.

Fatty acid nitriles are important chemical intermediates that are further processed in particular to form primary amines and quaternary ammonium salts, which in turn can be used in particular as textile auxiliaries, flotation aids and as cationic surface-active substances in many technical processes. Glycerin is an important chemical compound that is used, for example, for the production of explosives, as an additive to heat and power transmission fluids, as a moisture-preserving additive to skin creams, toothpastes, soaps, tobacco and the like, as textile auxiliaries, as solvents and in many other fields that Are known in the art, can be used.

The process according to the invention is illustrated by the following examples:

example 1

The reaction was carried out in a heatable reactor with a capacity of 800 cm ³ , provided with a gas inlet device, stirrer, internal thermometer and a fractionating column in the form of a glass tube filled with Raschig rings (length 20 cm, diameter 1.5 cm) and one consisting of three feeds connected in series Master system in which the volatile reaction products are condensed. In this apparatus, 495 g of tallow (saponification number 190, acid number 7.6) were introduced together with 5 g of zinc dodecylbenzenesulfonate as a catalyst. The apparatus was flushed with nitrogen while heating. The nitrogen was then replaced by ammonia gas, 600 l of NH ₃ / kg of tallow. h were circulated. Fresh ammonia gas was continuously added during the reaction. The following temperature profile resulted in the reactor:

After a total reaction time of 7 hours, the reaction of tallow with ammonia had ended. In this process, tallow grease nitrile and glycerin were collected in two series connected templates. In a further downstream receiver, the ammoniacal water of reaction was condensed.

The glycerol and tallow nitrile collected in the first two templates during the reaction, which is obtained in two phases, was separated and the tallow nitrile was washed with water. Tallow fat nitrile obtained in this way was obtained in 93.6% yield (413.7 g), based on theory, at 1.8% by weight amide content and 1.5% by weight tallow fatty acid and pure glycerol after working up with 80.2% (39 , 6 g) yield isolated. (Here and below, the yield values are always to be understood in relation to theory.)

Example 2

In the apparatus described in Example 1, 495 g of beef tallow (saponification number 190, acid number 1.6) together with 10 g of zinc dodecylbenzenesulfonate were pre-gelated, and starting at 230 ° C., an amount of 600 l NH ₃ / kg of tallow was passed through the fat headed. The following temperature profile in the reactor was observed:

The total reaction time was 7.5 hours. The reaction products discharged into the templates were washed out with water and worked up. Tallow fatty nitrile was obtained in a yield of 92.3% (408 g) with an amide content of 0.7 wt .-% and a fatty acid content of 0.5 G _ew .-%, and crude glycerol with a yield of 87.7% (44.7 g ) receive. According to the OH number of 1694, the isolated raw glycerol contained 81.2% glycerol, based on the tallow used.

Example 3

In the described apparatus of Example 1 445 g of technical tallow ( "bleachable _tallow") (saponification number 186, acid number 12.6) and 9 g of zinc dodecylbenzenesulfonate were charged and reacted under the reaction conditions of Example 2 with ammonia. The reaction products discharged within 7.5 hours during the reaction were combined and washed out with water glycerol. After separation of the aqueous phase, tallow fatty nitrile could be isolated in 93.0% yield (370.4 g, amide content 0.5% by weight and fatty acid content of 0.3% by weight). Crude glycerol was obtained from the aqueous phase in 97.5% yield (38.5 g). The yield of pure glycerol, according to the OH number of 1683, was 84.0%, based on the tallow used.

Example 4

In the apparatus described in Example 1, which was equipped here with a 70 cm mirror glass column with Raschig rings for fractionation, 488 g of tallow (saponification number 190, acid number 2.4) and 5 g of zinc toluenesulfonate were added. A weak stream of nitrogen was passed through the reactor during heating. At 190 ° C the changeover to 600 l NHjkg fat h was made. The reaction was carried out at 230 ° C for 3 hours. The mixture was then heated from 230 ° C. to 270 ° C. within half an hour and the temperature was kept at 270 ° C. for a further 3.25 hours.

After a total of 6.75 hours, all volatile reaction products were then out of the reactor carried over the column. The glycerol / tallow fat nitrile mixture collected in the original system was then treated with water. After working up both phases, tallow fatty nitrile could be obtained with a yield of 93.2% (406 g, 1.7% amide content, 0.5% by weight fatty acid content) and pure glycerol with a yield of 80.1% (40.1 g) will.

In the same apparatus and under the same test conditions, food tallow was also reacted in the presence of further catalysts. The test results are tabulated below:

Example 5

In the apparatus described in Example 4, 436 g of sunflower oil (saponification number 189, acid number 0.8) and 9 g of zinc dodecylbenzenesulfonate as a catalyst were reacted with ammonia gas (690 I / kg of fat) under the conditions given in Example 4 (6.75 hours reaction time) - h) implemented. After working up 94.6% fatty nitrile (amide content 0.5% by weight, fatty acid content 0.35% by weight) and 91.2% crude glycerol (40.9 g) or, according to the OH number of 1717, 85.6 % Pure glycerin, based on 01 used, obtained.

Example 6

The production of fatty acid nitrile and glycerol directly from glycerides is also possible using a continuous procedure. In a heatable, cylindrical 750 ml glass vessel, 192 g of food tallow were placed together with 7.5 g of zinc dodecylbenzenesulfonate. The reactor was equipped with a stirrer, internal thermometer, heated dropping funnel and a 70 cm mirror glass column filled with Raschig rings. 600 l of ammonia / kg of fat - h were passed into the reactor from below using a frit at 230 ° C. Under these conditions, 1009 g of tallow mixed with 1% by weight of zinc dodecylbenzenesulfonate were metered in over the course of 3 hours (27-29 g of tallow / h). The volatile reaction products continuously discharged through the column were condensed in the initial system. The resulting tallow fat nitrile was freed from glycerol using water. Tallow fat nitrile could be isolated in 96.1% yield (1033 g; 1.4% amide content). Crude glycerol was isolated from the water in 95.5% yield (115.4 g).

Example 7

486 g of table tallow (saponification number 190, acid number 1.6) and 5 g of zinc dodecylbenzenesulfonate were initially introduced into the apparatus described in Example 4. At about 270 ° C., 500 l of NH ₃ / kg of fat - h were constantly passed through the reaction mixture. The reaction time was 6.5 hours. The recovery products discharged into the templates were washed with water and worked up. Tallow fatty nitrile was obtained in a yield of 93.7% (406 g) with an amide content of 2.2% by weight and a fatty acid content of 0.4% by weight and pure glycerol with a yield of 73.45% (36.8 g), based on the tallow used.

Example 8

486 g of tallow (saponification number 187.5, acid number 11.1) and 4.25 g of zinc salt of tallow fatty acid were added to the apparatus described in Example 4. During the heating, 30 IN ₂ / h were passed through the reactor and at 190 ° C. to 600 l NH ₃ / kg fat. h changed. The reaction was complete after 13 hours. The reaction temperature was initially held at 230 ° C. for 3 hours and at 270 ° C. for 9.5 hours after heating. The collected in the templates, out of the reactor Carried sebum follow-up products were washed with water. Tallow fatty nitrile was isolated in 84.6% yield (367.8 g) and pure glycerol in 60.4% yield (28.3 g), based on the tallow used.

Example 9

In the apparatus described in Example 1 and with the fractionation system specified in Example 4, 445 g of beef tallow (saponification number 186, acid number 0.8) were introduced together with 9 g of iron dodecylbenzenesulfonate as a catalyst. Starting at 230 ° C, 600 I NH ₃ / kg fat · h were passed through the sebum. The reaction temperature was raised to 290 ° C. in the course of 7.25 hours. After the end of the reaction and working up, 364.1 g of tallow fatty nitrile (91.4% yield) with an amide content of 2.9% by weight and a fatty acid content of 0.4% by weight and 30.2% pure glycerol (67.0%) resulted % Yield), based on the tallow used.

Example 10

445 g of beef tallow (saponification number 190, acid number 0.2) and 9 g of lead dodecylbenzenesulfonate were added to the apparatus described in Example 1 and then 600 l of NH ₃ / kg of fat - h, starting at a reaction temperature of 230 ° C., were passed through. The reaction temperature was raised continuously to 290 ° C. in the course of 7.25 hours. After the end of the reaction and working up, 350.5 g (88.2% yield) of nitrile with an amide content of 2.7% by weight and a fatty acid content of 0.35% by weight and 36.5 g pure glycerol (78, 9% yield).

Example 11

445 g of soybean oil (saponification number 203.2) together with 9 g of zinc dodecylbenzenesulfonate were placed in the apparatus described in Example 1. Starting at 230 ° C, 600 I NH / kg fat - h were passed through the oil. The reaction temperature was raised to 290 ° C. in the course of 7.25 hours. After the end of the reaction and working up, 363.3 g of soyanitrile (92.2% yield) with an amide content of 0.7% by weight and a fatty acid content of 0.7% by weight and 36.0 g of pure glycerol (yield 72 , 8%, based on the oil used).

Example 12

445 g of beef tallow (saponification number 192, acid number 0.25) and 9 g of cadmium dodecylbenzenesulfonate were placed in the apparatus described in Example 1. Starting at 230 ° C, 600 l NH ₃ / kg fat · h were passed through the fat. The reaction temperature was raised to 290 ° C. in the course of 6.5 hours. After the reaction and working up, 373.6 g of tallow fatty nitrile (94.2% yield) with an amide content of 2% by weight and a fatty acid content of 0.7% by weight and 75.2% yield of pure glycerol (35, 1 g) received.

Example 13

445 g of beef tallow (saponification number 192) and 9 g of cobalt dodecylbenzenesulfonate were placed in the apparatus described in Example 1. Starting at 230 ° C 600 I NH ₃ / kg fat - h were passed through the fat. The reaction temperature was raised to 290 ° C. within 7.25 hours. After the end of the reaction and working up, 373 g (94% yield) of tallow nitrile with an amide content of 4.9% by weight and a fatty acid content of 0.8% by weight and a crude glycerol yield of 86.4% (40.3 g ).

Example 14

In the apparatus described in Example 1, which, however, was equipped with a direct transition piece from the reactor to the feed system instead of a fractionation unit, 486 g of food tallow (saponification number 187, acid number 0.8) were obtained together with 1% by weight of zinc dodecylbenzenesulfonate on tallow. During the reaction 600 I NH ₃ / kg fat. h passed through the reaction material. The temperature was kept at 230 ° C. for 3 hours and after heating (0.5 hours) at 270 ° C. for 1.25 hours. The reaction was complete after a total of 4.75 hours. The reaction products discharged into the templates at 230 ° C. and 270 ° C. were each collected and worked up separately. The fatty acid nitrile isolated at 230 ° C. had an amide content of 20% by weight. At 270 ° C., an amide content of approximately 9% by weight was observed. The amide content in the entire fatty acid nitrile was 10% by weight.

Example 15

In the apparatus described in Example 1, which, however, was equipped with a direct transition piece from the reactor to the feed system instead of a fractionation unit, 500 g of tallow (saponification number 189, acid number 0.9) together with 2% by weight of zinc dodecylbenzenesulfonate, based on Tallow. During the reaction, 600 l of NH ₃ / kg fat - h were passed through the reaction mixture. The temperature was kept at 230 ° C. for 3 hours and then increased by 10 ° C. and after every half hour by a further 10 ° C. The reaction was complete at 280 ° C. The reaction time was 5.25 hours. The entire condensate was in water at 80 ° C in fatty acid nitrile and Glycerin / water separated. The isolated fatty acid nitrile had an amide content of 5.3% by weight and a fatty acid content of 0.5% by weight. The nitrile yield was 95.2%. After working up, pure glycerol could be obtained with a yield of 91.4%.

Example 16

In a heatable reactor, which is equipped with a gas inlet tube, a stirrer and an internal thermometer and to which a feed system (condensation system consisting of one or more feeds, containers) is attached, 500 g of technical tallow (saponification number 191.4, acid number 1.5) would together with 2 wt .-% zinc dodecylbenzenesulfonate, based on tallow, submitted. The mixture was then heated to 230 ° C. and 600 l of ammonia per kg of fat - h were passed through the reaction mixture. The temperature was kept at 230 ° C. for 3 hours and then continuously increased to 260 ° C. over the course of 1.5 hours. After a total of 4.5 hours, the discharge of glycerol had ended and about half of the crude fatty acid nitrile had also been discharged. At this point in the reaction, the ammonia throughput was reduced to 60 l / kg of reaction material and the reaction temperature was increased to 290 ° C. at the same time. During the heating, the water washing of the glycerol-containing crude nitrile was carried out, which was then freed of glycerol and returned to the 290 ° C. reactor. After a total reaction time of 6.5 hours (after-reaction 2 hours), the tallow fatty nitrile was discharged and the catalyst was removed by distillation. 417 g (93.2% yield) of tallow fatty nitrile with an amide content of less than 0.06% by weight and an acid number of 0.1 and (according to the OH number) 42.9 g of pure glycerol (82.7% yield) were obtained .

Example 17

In the apparatus described in Example 1, 500 g of technical tallow (saponification number 191.4, acid number 1.5) were preassigned together with 2% by weight of zinc dodecylbenzenesulfonate, based on tallow. During the reaction, 600 l of ammonia per kg of fat and hour were passed through the reaction mixture, the temperature being kept at 230 ° C. for 3 hours and then being raised continuously to 280 ° C. over the course of 2.25 hours. The total reaction time was 5.25 hours. During the implementation, care was taken to ensure that the temperature gradient between the bottom and the transition was as small as possible. The condensate obtained was separated into crude fatty acid nitrile and glycerol by means of water washing.

The isolated 432.8 g of crude fatty acid nitrile (amide content 6.1% by weight) were placed in a reactor equipped with a gas inlet tube, stirrer, internal thermometer and condensation system, and 2% by weight of zinc dodecylbenzenesulfonate were added. 60 l of ammonia per kg of reaction material were passed through the reaction mixture at 290 ° C. per hour. Water of reaction formed was discharged. The reaction time was 1 hour. After distillation of the reactor contents, 415 g of tallow fatty nitrile (93.1% yield) with an amide content of less than 0.05% by weight and an acid number of 0.1 were present. Pure glycerol (according to OH number) was obtained 47.3 g (91.2% yield).

Comparative example (analogous to GB-PS 451,594)

Through a glass tube filled with 800 cm ^{3 of} grained aluminum oxide, 300 l of NH ₃ / l catalyst - h and 50 g of beef tallow per hour were passed through from below at 320 to 360 ° C. A total of 1342 g of beef tallow were added. The volatile reaction products that emerged from the top of the reactor were collected in a template system and washed with water after being combined. 1191 g of crude tallow fat nitrile (99% yield) were obtained, but of poor quality (colored black and pungent odor). Glycerin could not be detected. Theoretically, 140 g of glycerin were to be expected.

Claims (7)

1. A process for converting mono-, di- and triglycerides of the formula

wherein R_1' R₂, and R₃, identical or different, are aliphatic hydrocarbon radicals or mono-hydroxy substituted hydrocarbon radicals having from 3 to 23 C atoms, or mixtures of said glycerides in the liquid phase with ammonia yielding fatty acid nitriles of the formula R, (R₂, R₃)-N and glycerol by passing gaseous ammonia optionally in admixture with an inert gas at elevated temperatures in the presence of a catalyst, which is characterised by contacting intimately the liquid glyceride with a flow of at least 200 liters ammonia per kilogram of glyceride and hour at temperatures of from 220 to 300°C in the presence of a salt of a carboxylic or sulfonic acid and a metal selected from the group of lead, zinc, cadmium, tin, titanium, zirconium, chromium, antimony, manganese, iron, nickel, and cobalt as catalysts, discharging the resulting product mixture with rapid removal of the glycerol formed from the reaction zone, and subjecting the product mixture to a phase separation into a fatty acid nitrile phase and glycerol/water phase.

2. The process according to claim 1, characterised by raising the temperature gradually or continuously from 20°C to 300°C during the course of the reaction.

3. The process according to claims 1 and 2, characterised by maintaining in the starting phase of the reaction a temperature level in the range of from about 220 to about 240°C until between 30 and 70 percent of the theoretical amount of glycerol is removed from the reaction, then raising the temperature over a period from about 0.5 to about 5 hours to a temperature level in the range of from about 270 to about 300°C and completing the reaction.

3. The process according to claims 1 to 3, characterised by subjecting fatty acids and fattv acid amides contained in said discharged product mixture to an after-treatment, optionally following the phase separation, in the presence of ammonia and of the catalysts as defined in claim 1.

5. The process according to claims 1 to 4, characterised by subjecting the discharged product mixture to fractionation prior to the phase separation whereby recycling fatty acids and fatty acid amides contained in said discharged product mixture into the reaction.

6. The process according to claim: to 4, characterised by continuing the reaction until substantially the entire amount of gtyceroi is discharged, combining the fatty acid nitrile phase following the phase separation with the unremoved nitrile portion and treating said combined nitriles with a flow of ammonia of from 5 to 150 liters ammonia per kilogram fatty acid nitril and hour at temperatures of from 200 to 320°C in the presence of the catalysts as defined in claim 1.

7. The process according to claims 1 to 6, characterised by carrying out the reaction in the presence of lead, cadmium, iron, cobalt and zinc salts of alkylarene-sulfonic acids wherein the alkyl radicals have 1 to 24 carbon atoms, optionally substituted with one or two carboyxlic groups, as catalysts.