EP0938535B1 - Detergent and anti-corrosive additive for fuels and fuel composition - Google Patents

Abstract

PCT No. PCT/FR97/01634 Sec. 371 Date Jun. 16, 1999 Sec. 102(e) Date Jun. 16, 1999 PCT Filed Sep. 17, 1997 PCT Pub. No. WO98/12283 PCT Pub. Date Mar. 26, 1998The invention concerns a detergent and anti-corrosive additive for engine fuels, in particular gas oil, containing amide or imide functions characterised in that it is obtained by mixing wt. 60 to 90% of a compound A consisting of at least one carboxylic polyalkenyl, diacid or anhydride, of average molecular mass between 200 and 3000, wt. 0.1 to 10% of a compound B consisting of at least one carboxylic compound, monoacid or anhydride, containing 1 to 6 carbon atoms per chain and 10 to 30% of a compound C consisting of at least one primary polyamine of general formula H2N-[-(CHR1-(CH2)p-CHR2)n-NH]m-H, the mol ratios A/B/C corresponding to 1/(0.1 to 1)/(1 to 3), A/B/C never being 1/1/1.

Description

The present invention relates to an additive bifunctional with detergent and anti-corrosion functions which, when added to engine fuels, considerably reduces problems related to corrosion of parts of the engine and the formation of deposits.

Indeed, the use of conventional fuels without detergent and anti-corrosion additives promotes accumulation of deposits in the intake system, especially at the level of the injectors which get dirty, even in the combustion chamber, following the presence of polar aromatics and traces of lubricants.

The accumulation of deposits deteriorates the quality of fuel vaporization which causes an increase consumption, increased emissions of pollutants and smoke, significantly more important during acceleration, and finally a significant increase in noise.

To remedy this problem of fouling of the motor, it is possible to periodically clean the dirty parts and especially the injectors, but, in the long run, this process becomes very expensive.

Another method of reducing fouling by deposits in engines and in particular on injectors, is to add additives to the fuel detergent type whose role is to absorb on metal surfaces to prevent the formation of deposits (preventive effect) and / or eliminate deposits already formed in restoring the cleanliness of the injectors (curative effect). Thus, among the additives used in fuels, and even in lubricants, we know more particularly products from the condensation of anhydrides polyalkenylsuccinics on polyamines such as tetraethylenepentamine, described in US Patent 3,172,892. If these additives work well to limit the formation of deposits on new injectors, they remain however not very effective at cleaning injectors already dirty.

Other detergent additives, described in the EP patent 613.938, consist of substituted succinic diamides with polyalkylenes, preferably polyisobutenes comprising from 35 to 300 carbon atoms, the resulting diamide condensation of an N-alkylpiperazine secondary amine on either a substituted succinic acid or a anhydride, either an ester or a monoamide derivative; these additives are preferably used in fuels type petrol.

In addition, such compounds are known for their dispersing properties in lubricants as described in Patent EP 72,645.

However, if these compounds are good detergents, they do not completely prevent deposit formation and have a limited or even no curative effect. Thus, the present invention targets a bifunctional additive with detergent properties and anti-corrosion, compatible with other additives usually introduced into fuels, in particular diesel, reducing and even preventing the formation of deposits at the injectors while limiting phenomena corrosion and maintaining good dispersion.

In US patent 5,034,018, fuel additives are described which aim to limit fouling at the level of the injectors of an internal combustion engine obtained from amido-amine compounds comprising free NH ₂ ends on which reacted mono and dicarboxylic compounds so as to prepare amidoimides.

The subject of the present invention is a bifunctional additive, for engine fuels, in particular diesel fuels, with detergent and dispersing properties comprising amide or imide functions resulting from the condensation of a compound C consisting of a primary polyamine with a compound A consisting of at least one polyalkenyl carboxylic compound, diacid or anhydride and a compound B consisting of at least one carboxylic compound, monoacid or anhydride, linear or branched, the said additive being characterized in that it is obtained by reacting a compound C of general formula (I) below: H 2 N - [- (CHR 1 - (CH 2 ) p - CHR 2 ) not - NH] m - H in which R ₁ and R ₂ , identical or different, represent hydrogen or a hydrocarbon group comprising from 1 to 4 carbon atoms, n is an integer varying from 1 to 3, m is an integer varying from 1 to 10 , and p is an integer equal to 0 or 1, on a mixture of the two compounds A and B contained in an organic solvent with a boiling point of between 65 and 250 ° C., the compound A, a polyalkenyl carboxylic compound comprising 2 to 20 carbon atoms per linear or branched alkenyl group and having an average molecular mass varying from 200 to 3000, and compound B being chosen from the group consisting of methacrylic acid, acrylic acid, maleic anhydride and succinic anhydride.

According to the invention, the compounds A, B and C are used in A / B / C molar ratios preferably corresponding to 1 / (0.1 to 1) / (1 to 3) and are necessarily different from 1/1 / 1. Indeed, there is always an excess of polyamine in the chosen composition which leads to leaving free a certain number of NH ₂ terminations of polyamine C. Preferably, the C / A molar ratio varies from 1.3 to 2.0 and the ratio molar B / A varies from 0.1 to 0.8.

Compared to known additives, the combination of compounds mono and dicarboxyls in addition to a polyamine, promotes detergency and anti-corrosion effect of additives according to the invention. It corresponds to a synergistic effect of combination of these three components together.

The average molar mass of polyalkenyl compounds according to the present invention preferably varies from 200 to 2000 and most often from 200 to 1500. These compounds are well known in the prior art; they are notably obtained by reaction of at least one α-olefin or at least one chlorinated hydrocarbon, both linear or branched, on maleic acid or anhydride. This olefin or this chlorinated hydrocarbon contains from 10 to 150 carbon atoms in general, preferably 15 to 80 carbon atoms and more often 20 to 75 carbon atoms in their molecule. The olefin can also be an oligomer, such as a dimer, a trimer or a tetramer or a polymer of an olefin lower comprising from 2 to 10 carbon atoms such that ethylene, propylene, n-butene, isobutene, n-hexene, n-octene-1, methyl-2-heptene-1 and propyl-2-propyl-5-hexene-1. Onne would not go beyond the scope of the invention if we mixed several olefins or several chlorinated hydrocarbons.

In a preferred embodiment of the invention, the compounds polyalkenyl carboxyls are chosen from derivatives polyalkenyl succinic acids and anhydrides, the index anhydride varying from 0.5 to 1.2 milli-equivalents of potash per gram of product.

Among the succinic anhydrides, the anhydrides preferred are n-octadecenyl succinic anhydride, dodecenyl succinic anhydride and anhydrides polyisobutenyl succinics and all anhydrides succinics of weight average molecular weight varying from 200 to 1500.

In a preferred embodiment of the invention, the compound B is preferably chosen from the group consisting of methacrylic acid, acrylic acid, anhydride maleic, succinic anhydride, malonic acid, acid fumaric and adipic acid.

Among the primary polyamines according to formula (I), polyamines from the group consisting of diethylene triamine, dipropylene triamine, triethylene tetramine, tetraethylene pentamine and their derivatives substituted.

The mixing of these compounds A, B and C can be done either in this order or in a different order. However, in a preferred mode, product C is added, that is to say the primary polyamine of formula (I) on the mixture of products A and B, i.e. the mixture of carboxylic hydrocarbons. We usually operate in gradually introducing polyamine C to a solution in an organic solvent of this mixture of carboxylic hydrocarbons at ordinary temperature, then the temperature usually rises between 65 and 250 ° C and preferably between 80 and 200 ° C. The organic solvent necessary for solubilization is chosen for its point boiling range between 65 and 250 ° C and its ability to remove the water formed by condensation of the polyamine on mixture A + B, by azeotropic distillation of the mixture water / solvent. The solvent is preferably chosen from the group consisting of benzene, toluene, xylenes, ethylbenzene and commercial hydrocarbon cuts, for example those distilling from 190 to 209 ° C and containing 99% by weight of aromatic compounds. Of course, we don't would not go beyond the scope of the invention, if a mixture of solvents, in particular a mixture of xylenes, or another xylene / alcohol mixture, in particular ethyl-2-hexanol on the one hand, to facilitate the homogeneity of the environment and, on the other hand, to favor the kinetics of the reaction. After the addition of the primary polyamine C has been completed, keeps heating under reflux until elimination complete with water contained, usually for 0.5 to 7 hours, preferably 1 to 5 hours.

A second object of the invention is a fuel consisting mainly of a middle distillate from a direct distillation cut of crude oil between 150 and 400 ° C or any other index fuel cetane greater than or equal to 30, and for a minor part with the bifunctional additive (s) detergent (s) and anti-corrosion according to the first object of the invention.

In a preferred mode of this fuel, the concentration of detergent and anti-corrosion additive (s) is greater than 50 ppm, preferably varying from 60 to 600 ppm.

According to the present invention, it is possible to add to the said fuel at least one additive from the group of additives oiliness, additives improving the cetane number, demulsifying additives and modifying additives smell.

The examples below are intended to illustrate the invention without limiting its scope.

EXAMPLE I

This example describes the preparation of several samples of bifunctional detergent additives and anti-corrosion according to the invention.

These samples according to the invention are referenced X _i and the comparative examples C ₁ , i corresponding to a numbering making it possible to differentiate them.

The composition of these samples is given in Table I below: Sample AT B VS IT B / A C / B 4 Nature a (moles) Nature b (moles) nature c (moles) X ₁ At ₁ 0.03 WADA 0.01 TEPA 0.04 1.33 0.33 4 X ₂ At ₁ 0.03 AS 0.01 TEPA 0.04 1.33 0.33 4 X ₃ A ₂ 0.03 WADA 0.01 TEPA 0.04 1.33 0.33 4 X ₄ At ₁ 0.03 WADA 0.01 TEPA 0042 1.4 0.33 4.2 X ₅ At ₁ 0.03 WADA 0.01 TEPA 0.05 1.6 0.33 5 X ₅ At ₁ 0.03 WADA 0.02 TEPA 0048 1.6 0.60 5.8 X ₇ At ₁ 0.03 WADA 0.01 TEPA 0054 1.8 0.33 5.4 X ₈ At ₁ 0.03 AS 0.01 TEPA 0.06 2 0.33 6 X ₉ At ₁ 0.03 AS 0015 TEPA 0.79 2.4 0.45 7.9 X ₁₀ At ₁ 0.03 WADA 0025 TEPA 0.04 1.3 0.8 1.6 C ₁ At ₁ 0.03 TEPA 0.03 1 C ₂ WADA 0.1 TEPA 0.1 1 C ₃ At ₁ 0.03 WADA 0.03 TEPA 0.03 1 1 1 A ₁ = polyisobutenyl succinic anhydride with an average molecular weight of 950 and an anhydride index equal to 0.7 milli-equivalent of potash per gram A ₂ = polyisobutenyl succinic anhydride with an average molecular weight of 950 and an anhydride index equal to 0.8 milli-equivalent of potassium hydroxide per gram, sold under the reference ADX 104 by the company ADIBIS. AMA = methacrylic acid AS = succinic anhydride TEPA = tetraethylene pentamine

The samples X ₁ collected in this table I are obtained according to the following procedure.

A mole of polyisobutenyl succinic anhydride A, b moles of compound B, 25 ml of ethyl-2-hexanol and 25 ml of xylene are introduced successively into a 250 ml tetracol flask. The mixture is stirred and heated to 100 ° C. until a homogeneous medium is obtained, then about 5 moles of tetraethylenepentamine or TEPA, C. are added over 5 minutes. The whole is maintained at the same temperature under reflux for three to four hours until a constant volume of extracted water is obtained (1.05 ml). The products obtained have two infrared absorption bands characteristic of the imide functions at 1700 cm ^-1 and of the amide functions at 1670 cm ^-1 .

For the comparative examples C ₁ , C ₂ and C ₃ , the operation is carried out as above for the samples X _i , but by modifying the proportions in compounds A, B and C. By infrared spectroscopy, characteristic absorption bands are observed imides at 1700cm ^-1 (intense) and amides at 1670cm ^-1 (weak).

EXAMPLE II

This example aims to highlight the improvement detergent properties of samples according to the invention according to the relative concentrations of A, B and C, after addition in diesel fuel. It also aims to highlight the synergistic effect of the combination according to the invention.

• densité à 15 °C = 0,836 Kg/l
• point initial de distillation =174°C
• point final de distillation = 366°C
• indice de cétane = 53
• teneur en soufre = 0,24 % poids.

The diesel fuel used is a diesel engine whose main characteristics are:

• density at 15 ° C = 0.836 Kg / l
• initial distillation point = 174 ° C
• distillation end point = 366 ° C
• cetane number = 53
• sulfur content = 0.24% by weight.

The tests were carried out on diesel fuel alone or additivated with one of the additives X _i according to the invention or the comparative detergents C _i , at a concentration by weight of active material of 175 ppm.

These tests consist in following the engine test procedure as described in the literature published by the SAE (Society for Automotive Engineers) under the reference SAE # 922184 of 1992. They are carried out on a set of two Kubota Z 600 B generator sets driven by 570 cc ^3- stroke 4-stroke diesel engines with indirect injection.

• régime moteur : 3000 t/mn
• charge : 2/3 de la charge maximale.

Each test is carried out for a period of 6 hours under the following conditions:

• engine speed: 3000 rpm
• load: 2/3 of the maximum load.

At the start of each test, the engines are fitted with new injectors, the flow rates of which were measured prior to their installation, at different needle liftings from the injectors. At the end of each test, the injectors are disassembled, and their flow rates are measured for the same needle lifts. The effectiveness of the detergent additives tested is compared on the basis of their percentage of residual flow rate (% dr) calculated by the formula below. % Residual flow = Average flow rate of injectors at end of test Average flow rate of new injectors × 100

Table II below collates the results obtained. Needle lift (mm) 0.05 0.10 0.20 0.30 0.40 0.50 Diesel only 10 14 23 31 40 54 diesel + X ₁ 48 53 62 73 83 88 diesel + X ₂ 50 59 78 87 92 93 diesel + X ₃ 77 80 89 92 93 93 diesel + X ₄ 54 60 70 80 86 91 diesel + X ₅ 64 74 82 89 93 95 diesel + X6 67 78 83 88 91 92 diesel + X ₇ 79 85 92 94 95 95 diesel + X ₈ 68 78 91 95 95 95 diesel + X ₉ 30 34 45 56 65 69 diesel + X ₁₀ 35 39 49 57 68 72 diesel + C ₁ 34 38 48 58 67 73 diesel + C ₂ 0 0 0 0 0 0 diesel + C ₃ 18 22 33 42 54 65

As shown in Table I, the additives according to the invention give residual flow rates much higher than those of diesel fuel alone and diesel fuel additivated with additives comparative detergents.

EXAMPLE III

This example aims to demonstrate the effectiveness of additives according to the invention for cleaning the injectors already fouled (curative effect) compared to additives C according to the procedure described in Example II. Before each test, the injectors are pre-fouled with a diesel without additive for 6 hours according to the procedure described in Example II.

Residual flows after the fouling phase with diesel only are those indicated in line 1 of the table II.

The efficiency of the additives for cleaning already dirty injectors is calculated according to the following formula: % efficiency = Average flow rate of injectors at end of test Average flow rate of dirty injectors (test flow rate) × 100 Needle lift (mm) 0.10 0.20 0.30 0.40 0.50 diesel + X ₁ 230 190 174 158 120 diesel + X ₂ 243 210 180 170 135 diesel + X ₃ 260 217 198 172 135 diesel + C ₁ 164 139 132 135 115 diesel + C ₃ 207 165 158 145 120

Efficacy results of additives with regard to cleaning of dirty injectors, collected in the Table III are given for each needle lift; they still show the superiority of additives according to the invention.

EXAMPLE IV

This example aims to show the superiority of additives according to the present invention with respect to comparative C additives.

Corrosion tests consist in determining the anti-corrosion effect of the additives in diesel fuel on samples of polished ordinary steel in the presence of synthetic seawater according to standard ASTM D665, for a period of 24 hours at the temperature of 60 ° C. They are expressed in% of corroded area. Fuel % of corroded surface Diesel only 100 Diesel + X ₁ 10 Diesel + X ₂ 10 Diesel + X ₃ 5 Diesel + X ₄ 5 Diesel + C ₁ 25 Diesel + C ₂ 60 Diesel + C ₃ 20

As shown in the results in Table IV, the additives according to the invention have excellent properties anti-corrosion, superior to those of known products.

Claims (7)

1. Detergent and corrosion-inhibiting additive for engine fuels, in particular fuels of diesel type, comprising amide or imide functional groups resulting from the condensation of a compound C, composed of a primary polyamine, with a compound A, composed of at least one polyalkenylcarboxylic diacid or anhydride compound, and a compound B, composed of at least one linear or branched carboxylic monoacid or anhydride compound, the said additive being characterized in that it is obtained by reacting compound C of general formula (I) below: H2N- [- (CHR1- (CH2)p - CHR2)n - NH]m - H    in which R₁ and R₂, which are identical or different, represent hydrogen or a hydrocarbon group comprising from 1 to 4 carbon atoms, n is an integer varying from 1 to 3, m is an integer varying from 1 to 10 and p is an integer equal to 0 or 1, on a mixture of two compounds A and B contained in an organic solvent with a boiling point comprised between 65 and 250°C, compound A being a carboxylic polyalkenyl compound comprising from 2 to 20 carbon atoms per linear or branched alkenyl group and having a mean molecular weight varying from 200 to 3000, and the compound B being selected from the group consisting of methacrylic acid, acrylic acid, maleic hydride and succinic anhydride, the molar ratios of A, B and C being such that A/B/C corresponds to 1/(0.1 to 1)/(1 to 3), it never being possible for A/B/C to be 1/1/1, the molar ratio C/A varying from 1.3 to 2.0, and the molar ratio B/A varying from 0.1 to 0.8.
2. Additive according to Claim 1, characterized in that the average molar mass of the polyalkenylcarboxylic compounds A varies from 200 to 2,000 and preferably from 200 to 1,500.
3. Additive according to one of Claims 1 to 2, characterized in that the polyalkenylcarboxyliccompounds are chosen from polyalkenylsuccinic acid and anhydride derivatives with an anhydride number varying from 0.5 to 1.2 milliequivalents of potassium hydroxide per gram of compound.
4. Additive according to one of Claims 1 to 3, characterized in that the succinic anhydrides are chosen from the group composed of n-octadecenylsuccinic anhydride, dodecenylsuccinic anhydride and polyisobutenylsuccinic anhydrides, and any succinic anhydride with a weight-average molecular mass varying from 200 to 1,500.
5. Additive according to one of Claims 1 to 4, characterized in that the primary polyamines are polyamines from the group composed of diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine and their substituted derivatives.
6. Fuel mostly comprising at least one middle distillate resulting from a crude oil direct distillation cut of between 150 and 400°C or any other fuel with a cetane number higher than or equal to 30 and comprising, to a minor extent, at least one additive according to one of Claims 1 to 5.
7. Fuel according to Claim 6, characterized in that it contains at least 50 ppm, and preferably from 60 to 600 ppm, of the detergent and corrosion-inhibiting additive or additives.