FI116680B - Process for the preparation of an additive for fuel and additive - Google Patents

Abstract

The invention relates to a method for manufacturing a lubricant additive to fuel, using fatty-acid compounds. In the method, saturated fatty acids, which are esterified and possibly aminated, with a high melting point are separated from a fatty-acid mixture by cooling, the mixture thus obtained being mixed again with the part of the original fatty-acid mixture from which the fatty acids with a high melting point have been separated, the necessary amount of this latter mixture being mixed with fuel as a lubricant. The fatty-acid mixture is separated in the presence of a solvent or solvent mixture containing alcohol groups and the solvent or solvent mixture are used to esterify the removed fatty acids. The said solvents are removed from the mother liquor and the esterified fractions are combined with the residue of the mother liquor and used as an auxiliary agent in fuel.

Description

116680

The present invention relates to a process for the preparation of a fuel excipient and to 5 excipients. In particular, it is a lubricating auxiliary which is particularly suitable for use as a diesel engine auxiliary.

Numerous improvements and 10 improvements to both engines and fuels have emerged as fuel prices, particularly those of internal combustion engines, continue to rise and environmental regulations become stricter.

In car engines, the diesel-cycle engine is gaining ground from gasoline engines due to the higher thermal efficiency of diesels. In addition to the old, even high compression ratio efficiency, operation has been improved by improved fuel injection into the combustion chamber.

At the same time, due to environmental requirements, the amount of sulfur in these fuels has been greatly reduced, along with the desulphurisation of poly-aromatic and other ring compounds, which in themselves have had good lubricating properties for high-pressure fuel injection equipment.

Fatty acids have proven to be good for fuel, especially diesel fuel; additives. However, fatty acids have a well-known disadvantage that they crystallize or readily crystallize from e.g. stearic acid and arachinic acid, i.e. fatty acids 25, as such, are not well suited to cold conditions. Even the esters of these acids, as fats, crystallize easily out of, for example, olive oil.

US Patent 6,129,772 discloses a fuel additive prepared from saturated fatty acids and oligomeric fatty acids using tertiary amines as crystallization inhibitors. The patent specifically emphasizes that mixtures of various saturated fatty acids are not used, but does not justify this.

U.S. Patent 5,578,090 relates to a fuel and a fuel additive, characterized in that it consists of esters of fatty acids, some of which are glycerol precursors and some are triglycerides.

WO 94/17160 discloses a fuel additive consisting of a fatty acid esterified with an alcohol contained in one or more carbons.

EP 826765 discloses a corresponding diesel fuel additive which is a partial ester of a fatty acid and a polyol, e.g., an ester of glycerin and monocarboxylic acid, which is added to the middle distillate at 75-200 ppm.

US 3,765,850 discloses a fuel additive obtained by reacting dicarboxylic acid with polyamides.

US Patent 6,156,082 discloses that it is not desirable to have the fuel lubricant esterified because the lubricity suffers. Instead, partial esterification with diethylene glycol and organic acid anhydride is shown here which gave good lubricity results.

U.S. Patent No. 6,194,361 discloses distilled tall oil fatty acids to provide: a useful lubricant by reacting tall oil fatty acids with diethyl 20 molamine and reacting the fatty acid with aminoethylpiperazine after the previous reaction. This compound is used e.g. lubricating oil wells with both oil and water emulsion.

U.S. Patent 6,197,731 discloses that a suitable two-stroke fuel lubricant is obtained by esterifying polyols with polycarboxylic acids.

JP 08092581 discloses how the -OH group of castor oil is esterified with a saturated mono-. ·· with valentine fatty acid, this is achieved at very low temperatures: · a functional lubricant.

US Patent 6,086,645 discloses how a fuel additive is advantageously obtained by making carboxylic acid amides from oleic acid for this purpose. . and / or linolenic acid.

116680 3 U.S. Patent No. 5,882,364 discloses a corresponding fuel additive consisting of esters of an unsaturated fatty acid and a polyhydric alcohol which are blended together in two different grades.

US Patent 6,203, 584 discloses a fuel additive consisting of esters of a polyhydric carboxylic acid and a polyoxyamine, and a mixture thereof of a carboxylic acid and a polyhydric alcohol ester.

U.S. Patent No. 5,997,593 discloses a fuel lubricant consisting of a reaction product of a carboxylic acid and an amine, wherein said amine is guanidine, amine guanidine, urea or thiourea.

U.S. Patent No. 6,051,039 discloses a diesel fuel additive obtained from an amine derivative of dicarboxylic acid which is an amine derivative of succinic acid or phthalic acid and a mixture thereof and NR3 from an amine wherein R contains 6 to 24 carbons. This mixture is added to the diesel fuel at a concentration of at least 1000 ppm.

U.S. Patent 5,556,972 discloses how fats can be fractionated by crystallization:, a stearic ester fraction off the oleic acid fraction in two steps and removing:. 20 said stearin fat fraction by filtration. This has resulted in a lower fat hardening point. The process is carried out by countercurrent crystallization and thus the melting point of, for example, margarine can be reduced.

U.S. Patent No. 5,952,518 discloses a method for removing high melting point fatty acid pots from other fatty acids. Here, an emulsifier is used to aid in cooling the mixture and removing the saturated fatty acids from the mixture by crystallization. Esters of polyhydric alcohol and fatty acids are used as emulsifiers. The fatty acids were hydrolyzed rapeseed or soybean oils.

30 Tall oil fatty acids, as described in many patents, work well. as lubricants for internal combustion engines, as well as their alcohol esters with alcohols and fatty acid amines. However, fatty acids as such would be the best lubricants. Saturated fatty acids and their derivatives have been reported to be particularly good lubricants.

116680 4

In particular, stearic acids and its salts have always been used as good lubricants.

According to patent application F1 20011214, the fatty acid composition 5 is subjected to a cold treatment in a heat exchanger in which saturated fatty acids such as stearic acid and arachinic acid are separated on a cold surface and this fraction is then esterified and aminated and combined with the mother liquor fraction. By doing so, the amount of these low temperature precipitating acids in the mother liquor can be reduced to about 1/4 to 1/5 parts. Further, in this cold crystallization, relatively many other fatty acids remain among the needle-like crystals formed in the inclusions, so that the concentration of stearic acid in the fraction to be esterified and aminated is only 4-fold higher than the initial concentration.

It is a further object of the present invention to further improve the process for producing fuel of the type described in the above-mentioned patent application. This is accomplished as set forth in the appended claims.

According to the present invention, the crystallization is used as a solvent for at least part of the solvent used in the subsequent step to crystallize the crystal phase. 20 and which solvent is removed by distillation from the mother liquor. Thus, it has been found that: in the presence of alcohol, a branched alcohol and the like, the crystalline phase is formed differently than in a needle-like manner without solvent. This makes it easy '; e.g. by centrifugation, separates the crystalline phase from the mother liquor phase.

A highly preferred alcohol is 2-propanol in the presence of, for example, stearic acid, in the presence of other fatty acids, in the form of lamellar readily settling and separating crystals. The same is achieved, for example, with propylene glycol-n-butyl ether (Dowanol PnB) having a boiling point of 170 ° C and a freezing point of -75 ° C. Similarly, propylene glycol-n-propyl ether having a boiling point of 149 ° C and a freezing point of - 80 ° C (Dowanol PnP). Further, for example, 1-methoxy-2-propanol (Dowanol PM glycol ether) can be advantageously used.

. * All of these exemplified compounds have in common a branched hydrocarbon chain and an -OH group at the end of the chain. With this -OH group, the product 116680 can be esterified with fatty acids.

According to the present invention, stearic acid and arachinic acid are typically crystallized from tall oil fatty acids in the presence of a cosolvent, which cosolvent may be an alcohol or ether which can be subsequently esterified as such or a solvent which does not impair further use. Surprisingly, it has been found that typical diesel oil or light fuel oil is also a co-solvent that improves crystal separation, although it is not esterified in the next step. However, the best cosolvent seems to be isopropanol. Thus, according to this invention, crystallized saturated fatty acids (<+ 5 ° C) are isolated by crystallization in the presence of a cosolvent, preferably esterified with branched alcohols or ethers containing -OH groups, distilled off from the mother liquor and used as auxiliary and lubricant for engine fuel, preferably diesel fuel. This also acts as a regular gasoline lubricant, which is needed when gasoline-powered car engines switch to direct fuel injection into a pressurized cylinder space, as is now the case with diesel engines.

: According to the observations made it is advantageous to use more than one OH-containing product for esterification and it is very advantageous that they are branched. or at least iso-alcohols or iso ethers of alcohol. When used as crystallization auxiliaries, they do not need to be removed at all from the crystalline phase, but only the same products distilled from the mother liquor phase prior to esterification are added to said crystalline phase. The use of more than one mixture containing more than -OH groups is advantageous in that it results in lowering the pour point of the mixture and, of course, also reducing the cloud point of the fuel to which said additive is blended.

Of the co-solvents promoting crystallization and crystal separation described above, isopropanol is by far the best. This alcohol has a boiling point of 82.5 ° C and is easily separated by distillation and easily esterified with an acid catalyst with fatty acids. The abrasion tests (HFRR + 60 ° C, ISO 12156-1) revealed that the fatty acid blend alone, obtained from vacuum distillation of tall oil (TOFA-2), was the best 116680 6 lubricant among diesel oils in the abrasion test, the mother liquor of the above crystallization being used.

Further, a DBE solvent (dimethyl glutarate + dimethyl adipate + dimethyl succinate), which provides complex esterification with said crystalline phase, can advantageously be used to aid in the above esterification process. DBE is a commercial solvent obtained as a by-product from the production of polyesters. This reaction of DBE and fatty acids resulted in a viscous liquid and the reaction liberated methanol.

An exemplary diagram of the process apparatus of the invention is shown in the accompanying figure. According to the figure, the product (fatty acid = FA) is introduced into the container 1 together with the solvent or solvent mixture, cooled e.g. in a heat exchanger 2 and allowed to crystallize with sufficient dwell time in vessel 3, followed by the mixture into a separator 4. The separator may be the crystalline phase is passed through a heater 7 to an esterification vessel 5, to which also a catalyst, e.g. phenolsulfonic acid or toluene sulfonic acid, is also introduced. The "mother liquor" obtained from the separator 4 is subjected to an order from which the solvent or solvents are recycled to vessel 1 and the bottom product of the distillation is combined with the esterified fatty acids obtained from vessel 5 to give the final product.

20

Results: Total excipient up to 500 ppm = Fatty acids + its esters in diesel-free oil.

Product Cloud point HFRR wear 25 Additive-free diesel oil -27.3 ° C 619 pm

Commercial winter quality diesel -42 ° C 410 pm. . Fatty acid stock solution - 24.3 ° C 265 µm

Fatty acid 500 ppm

: · As -28.0 ° C

30 TOFA mother liquor 50% + 50% PnP + PnB + DBE esters ............. -35.4 ° C 347 pm TOFA mother liquor 50% + DBE ester (crystalline phase) 116680 7 50% .......................... -34.5 ° C 294 pm TOFA mother liquor + isopropyl ester 25% + FA-diethanolamide 25% -42 ° C 317 pm 5

Cloud point measurements are not entirely uncontroversial but indicative. The accuracy of the measurements should be ± 2 ° C. The table above shows that good lubricating properties are already achieved with tall oil fatty acids alone at 500 ppm. However, they are not suitable for conditions below -27 ° C.

10

In all of the above, the esterification and possible amination were carried out as a crystalline part of the separated fatty acids and the co-solvents were distilled off from the mother liquor. FA [= Fatty acid] = fatty acid mixture. It is clear that isopropanol is very well distilled from the fatty acid mixture, but for example PnP and PnB are distilled poorly because PnB has a boiling point of 170 ° C and PnP has a temperature of 149 ° C. However, both products have a cloud point of -80 ° C. it is preferable to leave small amounts among the fatty acids.

Claims (10)

A process for the preparation of fatty acid compounds intended to be used as a lubricating additive in a fuel, wherein the process is separated by cooling from a high melting point saturated fatty acids which are esterified and optionally aminated, and the mixture thus obtained is mixed. new together with the portion of the fatty acid mixture from which the saturated acids of high melting point were separated and this last mixture is mixed in sufficient quantity with the fuel to act as a lubricant, characterized in that the separation from the fatty acid mixture is carried out in the presence of a solvent or solvent. containing alcohol groups, that the solvent or solvent mixture is used for the esterification of the removed fatty acids, that said solvent is removed from the parent solution, and that the esterified fractions are combined with the residue of the parent solution and used as the auxiliaries in the fuel. 15 Process according to claim 1, characterized in that esters containing alcohols or alcohol groups are used as solvents and having a boiling point below + 180 ° C. * »· *. 20 3. A process according to claim 1, characterized in that the solvents are selected from. the following group: isopropanol, tert. butanol, n-butoxypropanol, propylene glycol-n-propyl ether. * * · • · • · • * · i i ·. · · ·. Process according to claim 1, characterized in that the product separated by crystallization is at least partially esterified by complex esterification with: *. ·. methyl esters of dihydric organic acids. • »• ·. Process according to claim 1, characterized in that the fatty acid phase is separated in the presence of organic solvents with alcohol groups within the temperature range 0 - 5 ° C and the separation is carried out by filtering, precipitating or centrifuging. . 116680 Process according to any of the preceding claims, characterized in that the amount of solvent used with alcohol groups is 10-50% of the amount of fatty acid. Process according to any of the preceding claims, characterized in that at least 5% of the solvents consist of isopropanol. 8. Flaking agent for the production of fatty acid compounds which are intended to be used as a lubricating fuel additive, characterized in that it is prepared by the method according to any of claims 1 - 7. 10 Use of the aid according to claim 8 as a fuel additive. 15 »1 ·« t 0 tt 0 * r · • · li »• 1 ·» a • I 1 • »· t · • ·» 1 I • · · »· • · • ·> I» • »· tt II · a ·> »III» t III