MXPA00006186A - Ignition improved fuels - Google Patents

Abstract

A fuel is presented which is doped with 0.01-10%by weight of cyclic ketone peroxide(s), characterized in that it comprises from 0.01 to 10 percent by weight of cyclic ketone peroxides of formula (I) wherein R1-R6 are independently selected from the group consisting of hydrogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 aralkyl, and C7-C20 alkaryl, which groups may include linear or branched alkyl moieties;and each of R1-R6 may optionally be substituted with one or more groups selected from hydroxy, alkoxy, linear or branched alkyl, aryloxy, ester, carboxy, nitrile, and amido, with the proviso that said peroxides make up at least 35%by weight of all peroxides in the fuel, to reduce the emission of pollutants when the fuel is used in a combustion engine. Also the process to make such fuels is presented.

Description

COMBUSTIBLES WITH IMPROVED IGNITION DESCRIPTIVE MEMORY The invention relates to fuels with improved ignition characteristics comprising one more ketone peroxides, as well as a process for preparing such fuels. The use of peroxides in fuels has been common knowledge for quite some time. In the 1940s the patent E.U.A. 2,378,341 described the use of a peroxide of a hydrocarbon having at least one aliphatic tertiary carbon atom, the peroxy radical connecting said tertiary carbon atom to said peroxide, while the document Ind. Eng. Chem., Vol. 41 No 8, pp. 1679-1682 described the use of di-tert-butyl peroxide and 2,2-bis (tert-butylperoxy) butane for the purpose of improving the ignition of diesel fuels. In addition FR-B-862,070 described a rather dangerous process that is conducted at undesirable low temperatures, to make polymeric ketone peroxides from mixtures of aliphatic ketones and their use in fuels. It is said that the products have improved solubility in the fuel and a low crystallization temperature. FR-B-862,974 discloses the production of certain cyclic ketone peroxides and their use in diesel fuels to improve the ignition characteristics.

In 1961, the patent E.U.A. 3,003,000 described ketone peroxides and oligomeric ketone peroxides, a process for making them, and their generic use, among other things, in diesel fuels. The process also supplies some cyclic ketone peroxide byproducts. These by-products are present in the oligomeric peroxides of ketones in trace amounts. In addition, the use in formulations for diesel fuel is not exemplified. The patent E.U.A. 3,116,300 (published in 1963) describes cyclic dimeric ketone peroxides, that is, the product formed when two ketone molecules are reacted. Ignition improvers are desired to be used in hydrocarbon distillates and oils containing residues that are useful as combustion engine fuels except for their ignition characteristics. In the usual way, such fuels have a fairly long ignition delay, that is, the time between the injection of the fuel into the combustion zone, as in directly injected engines such as diesel engines, and the time when the fuel is ignites, or the time between activation of external ignition sources, such as spark plugs, and the time the fuel is ignited. As a result, low combustion efficiency and a rough motor operation are observed, with all the respective adverse consequences. Therefore, the term "improved ignition" means that in combustion engines the fuel is burned with improved efficiency, which is usually evident from the higher cetane number of the fuel and the reduced emission of pollutants after combustion of the fuel. fuel in said engine. As is well known, the use of diesel fuel, with improved ignition can result in reductions in emissions of hydrocarbons, carbon monoxide, NOx, and particulate matter (soot). Depending on the type of fuel and the type and amount of ignition improver used, reductions of up to 40% of these emissions are completely possible. Despite the lapse of time since the invention of the ketone peroxides, they have not found any commercial use as ignition improvers. In contrast, the commercial products currently used to improve the ignition of fuels (diesel) are di-tert-butyl peroxide and 2-ethylhexyl nitrate, as indicated by Chemtech, 8-97, p. 38-41. However, these products have various disadvantages. Nitrates can lead to NOx formation after combustion, while di-tert-butyl peroxide has a low vaporization point and high volatility, which can lead to various safety risks. Most peroxides also do not have long-term (thermal) stability in diesel fuels. Especially at elevated temperatures such as can be found in fuel systems, decreased thermal stability can lead to rubber formation or other fuel degradation. In addition, the decomposition products of the peroxides are generally (partially) alcoholic in nature, which tends to increase the undesirable absorption of water by the fuel. In addition, most of the peroxides used to date have a relatively low active material content. In addition, the price / performance ratio of most peroxides is interposed to be widely introduced in fuels (diesel). In this regard, it is noted that the unsatisfactory performance of the ketone cyclic dimer peroxides as described for example in FR-B-862,974 is considered to lead to an unacceptable price / performance ratio of those products. In addition, the dimeric structure of conventional cyclic ketone peroxides may present a security risk, due to the volatility and low vaporization point of such products. Consequently, there is a need for fuels with improved characteristics. Surprisingly, some of the peroxide compositions described in WO 96/03397 were found to be very suitable for improving the ignition characteristics of fuels. WO 96/03397 relates to numerous formulations of cyclic ketone peroxides, such as those described below, comprising a variety of phlegmatizers. However, this patent application does not disclose or suggest the use of cyclic ketone peroxides in fuels. A comparison between the cyclic ketone peroxides of WO 96/03397 which have a good yield and the cyclic ketone peroxides according to, for example FR-B-869,974, showed that the surprising performance is related to the nature of the cyclic ketone peroxide that is used. Therefore, the invention is based on the proper selection of the ketone peroxide used to improve the fuel. The fuel according to the invention is characterized in that it comprises from 0.001 to 10% by weight of one or more cyclic ketone peroxides which are selected from the group of peroxides represented by the formula I: (Or in which Ri, R and R5 are independently selected from the group consisting of hydrogen, C2O2alkyl, C3-C20 cycloalkyl, Cß-C20 aryl) C7-C20 aralkyl and C7-C20 alkaryl, groups may include linear or branched alkyl portions, and R2, R4 and Re are independently selected from the group consisting of hydrogen, C2-C2alkyl, C3-C2o cycloalkyl > C6-C2o aryl C7-C20 aralkyl and C -C2o alkaryl, which groups may include linear or branched alkyl portions; and each of R Rβ may be optionally substituted with one or more groups selected from hydroxy, alkoxy, linear or branched alkyl, aryloxy, ester, carboxy, nitrile, and amido, with the proviso that said peroxides constitute at least up to 35. % by weight of all cyclic ketone peroxides in the fuel. The improved fuels according to the invention do not possess most of the aforementioned disadvantages. More specifically, it has been found that the use of cyclic ketone peroxides of formula I results in fuels with exceptionally good performance with respect to ignition timing and correlated cetane number, good miscibility, good chemical stability that is, resistance to oxygen, acids and metal oxides such as rust, and good compatibility with other parts of the fuel system, such as metals, accessories, gaskets and rubber hoses. Preferably, the ketone cyclic peroxides according to the invention consist of oxygen, carbon and hydrogen atoms, so that an adverse effect on NOx emission is avoided after combustion of the fuel in which they are incorporated. More preferably, the cyclic ketone peroxides according to formula I are obtained from at least one ketone with a molecular weight greater than acetone, so that the total number of carbon atoms in the molecule is greater of 6. The use of such higher molecular weight ketones will have a positive effect on the solubility of said cyclic ketone peroxide in a fuel and has been found to be more effective with an ignition improver, based on the amount of oxygen added asset. Preferably, a ketone with at least 4 carbon atoms, more preferred with at least 5 carbon atoms, is used to produce the cyclic ketone peroxide used according to the invention. In addition, the total number of carbon atoms in the cyclic ketone peroxide, according to the invention, is preferably less than 40, more preferred less than 30, and more preferably even less than 25. Otherwise the molecular weight will be very high, needing a high level of dosage of peroxide to fuel, which is not attractive from the economic point of view. Incidentally, it is indicated that if mixtures of ketones containing acetone are used, then some undesired amounts of dimeric and trimeric peroxides of acetone will be formed. Said cyclic acetone peroxides may precipitate at lower temperatures than those used in a fuel, particularly in a diesel fuel, and therefore an additional purification step may be required. Hence, the use of acetone in mixtures of ketones is also not desired. In addition, although mixtures of ketones can be used to make the cyclic ketone peroxides according to the invention, it is preferred to use only one ketone, such that such cyclic ketone peroxides are, among other things, more easily produced and are less prone to changes in composition due to changing processing conditions. Therefore, the quality of the ignition improvers formed in this way is more easily controlled. The ketone cyclic peroxide (s) preferably improving the ignition time is / are present in such an amount that the autoignition time of the treated fuel is shorter in a model test, as described later, than the autoignition time of the fuel without treatment. More preferred, a reduction of more than 10% in the autoignition time is observed at 270 ° C in said test. Even more preferred, the reduction of the autoignition time is greater than 25% at this test temperature. Even more preferred is a reduction of at least 50% of the autoignition time at 270 ° C. Preferably, one or more of the cyclic ketone peroxides according to formula I are present in the final fuel formulation in an amount between 0.025 and 5% by weight (% w / w). More preferred is a cyclic peroxide concentration of formula I in the fuel of between 0.05 and 2.5% w / w. A lower amount of peroxide will not result in any noticeable improvement in the ignition characteristics of the fuel, while a higher amount could show that it is unsafe or inexpensive. The term fuels, as used throughout this document, covers all hydrocarbon distillate materials and oils containing waste for use in combustion engines and which distill between the kerosene fraction and the oil lubricating oil fraction. . The fuel may comprise the usual additives, such as foam anti-fouling agents, injector cleaning agents, drying agents, cloud point depressants, also known as antigelificant agents, algae control agents, lubricants, dyes and inhibitors. of oxidation, but may also comprise additional ignition improvers or combustion improver additives, with the proviso that such additives do not adversely affect the storage stability of the final fuel composition according to the invention. A preferred fuel is a diesel fuel. In a second embodiment, the invention relates to a process for preparing fuels with improved ignition. For this purpose, an appropriate ketone cyclic peroxide composition is combined with a fuel, or else the cyclic ketone peroxide is directly produced in said fuel. The cyclic ketone peroxide (s) can be produced as described in WO 96/03397. This document describes how the resulting cyclic ketone peroxide composition can be controlled by changing the reaction conditions. Cyclic trimeric ketone peroxides according to formula I are preferably formed when mild reaction conditions are chosen, for example by decreasing the amount of acid used in the process, lowering the temperature, reacting for a short period, and / or dosing the hydrogen peroxide and the acid at the same time. In addition, the production of the trimeric compound is favored when less water is used in the reaction, probably because a lower amount of trimer compound is hydrolyzed to the dimeric compound. The exact conditions will depend on the type of ketone used and the concentration of the various reagents. However, the person skilled in the art will have no problem to determine which processing conditions are to be selected to produce the cyclic ketone peroxides as used in the invention. Preferably, however, the processing temperature is in the range of 0-80 ° C, more preferred 5-60 ° C and more preferred still 20-45 ° C to allow a cost-efficient process. Ketones suitable for use in the synthesis of cyclic ketone peroxides as used in the invention include, for example, acetone, acetophenone, methyl-n-amylketone, ethylbutylketone, ethylpropylketone, methyl isoamyl ketone, methylheptyl ketone, methylhexylketone, ethylamyl ketone, dimethylketone, diethyl ketone, dipropyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, methyl propyl ketone, methyl-tert-butyl ketone, isobutylheptyl ketone, diisobutyl ketone, 2,4-pentanedione, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, 3,5-octanedione, 5-methyl-2,4-hexanedione , 2,6-dimethyl-3,5-heptanedione, 2,4-octanedione, 5,5-dimethyl-2,4-hexanedione, 6-methyl-2,4-heptanedione, 1-phenyl-1,3-butanedione , 1-phenyl-1,3-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-2,4-pentanedione, melylbenzyl ketone, phenyl methyl ketone, phenylethyl ketone, and coupling products thereof. Of course, other ketones having appropriate R groups corresponding to the peroxides of the formula I can also be used, as well as mixtures of two or more different ketones.

Examples of preferred peroxides of the formula I to be used according to the present invention are cyclic ketone peroxides obtained from methyl n-amyl ketone, ethyl butyl ketone, ethyl propyl ketone, methylheptyl ketone, methyl hexyl ketone, ethylamyl ketone, methyl propyl ketone, diethyl ketone, methyl ethyl ketone, isomers of these ketones, and mixtures thereof. More preferred, the peroxides of the formula I are based on at least one ketone selected from the group consisting of methyl-n-amylketone, ethylbutyl ketone, ethylpropyl ketone, methylheptyl ketone, methylhexyl ketone, ethylamyl ketone, methylpropyl ketone, diethyl ketone, methyl ethyl ketone, and one or more isomers of these ketones, such as methyl isobutyl ketone and methylisopropyl ketone. The peroxides can be prepared, transported, stored and applied in any solid or liquid form, but solutions are preferred in a non-halogenated liquid phlegmatizer. These compositions can then be combined with the fuel. It should be noted that certain phlegmatizers may not be suitable for use in all ketone peroxide compositions of the present invention. More particularly, in order to obtain a safe composition, the phlegmatizer must have a certain minimum vaporization point and a minimum boiling point in relation to the decomposition temperature of the ketone peroxide, so that the phlegmatizer can not be evaporated leaving a concentrated, unsafe ketone peroxide composition. Preferred phlegmatizers are selected from the group consisting of hydrocarbons, such as fuels (diesel), paraffinic and white oils, oxygenated hydrocarbons, such as ethers, aldehydes, epoxides, esters, ketones, alcohols and organic peroxides, such as linear ketone peroxides and di-tert-butyl peroxide, alkyl nitrates, such as 2-ethylhexyl nitrate, and mixtures thereof. Examples of preferred liquid phlegmatizers for cyclic ketone peroxides include alkanols, in particular higher aliphatic alkanols, cycloalkanols, alkylene glycols, alkylene glycol monoalkyl ethers, ethers, in particular methyl tertiary butyl ether, aldehydes, ketones, epoxides, esters, hydrocarbon solvents. , including toluene, xylene, fuel (diesel), paraffinic oils and white oils. The most preferred liquid phlegmatizers are ethers and hydrocarbons. Even more preferred, a fuel such as phlegmatizer is used. A concentrated composition of cyclic ketone peroxides is very suitable for further diluting it with the fuel in order to obtain a fuel comprising an amount of said ignition-enhancing peroxide. The fuel according to the invention can only contain peroxides of the formula I as the ignition improver. However, these may be combined with other ignition improvers, such as conventional di-tert-butyl peroxide and / or 2-ethylhexyl nitrate. If the peroxides of the formula I are used together with other ignition improvers based on cyclic ketone peroxide, then it is preferred that they constitute at least up to 40% w / w, more preferred at least 45% w / w, more preferred still at least 50% w / w, still more preferred at least 66% w / w, and still more preferred even more than 75% w / w, based on the weight of all cyclic ketone peroxides in the fuel. More preferred are compositions in which more than 80% w / w of the weight of all cyclic ketone peroxides can be attributed to the cyclic ketone peroxides according to formula I, because the ignition properties of such fuels It is improved more efficiently. If only cyclic ketone peroxides consisting essentially of a mixture of dimeric and trimeric compounds (according to formula 1) in the fuel are used, then the preferred ranges indicated show that the ratio of dimeric to trimeric compounds in the fuel is lower of about 2: 1, more preferred less than about 3: 2, more preferred even less than about 5: 4, more preferred still less than about 1: 1, and even still more preferred less than 1: 2, more preferred less than about 1: 3, and preferably less than about 1: 4. To avoid security risks, it is preferred that the cyclic ketone peroxide composition used to make the claimed fuels is not essentially pure cyclic ketone peroxide. Preferably, the compositions comprise less than 99% w / w, more preferred less than 90% w / w and even more preferred less than 85% w / w cyclic ketone peroxide, all based on the weight of the total formulation. More preferred, the ketone cyclic peroxide composition that is used to make the fuels according to the invention comprises less than 75% w / w cyclic ketone peroxide based on the weight of the total composition. Alternatively, the cyclic peroxides can be prepared in a fuel, which can be the fuel whose ignition characteristics are to be improved, in the desired concentration of between about 0.01 and 10% w / w. For this purpose, conventional reactants and catalyst (catalysts) are introduced into the untreated fuel and reacted. Subsequently, the improved ignition fuel is separated from the contaminants and process water, optionally washed, and optionally dried, all in a conventional manner. In this preparation, the flows that are going to be processed are quite large in volume, but the handling of a concentrated peroxide material can be avoided. The invention is illustrated by the following examples.

EXAMPLES Materials used: Isopar® M phygmatizer based on hydrocarbon from Exxon Chemical. MeKP-1 cyclic cyclic peroxide methyl ethyl ketone (41% w / w in Isopar M) from Akzo Nobel 93% trimeric compounds, 7% dimeric compounds (% GC area). MEKP-2 cyclic cyclic peroxide methyl ethyl ketone (29.7% w / w in Diesel 1) from Akzo Nobel 85% trimeric compounds, 15% dimeric compounds (% GC area). 2-EHN 2-ethylhexyl nitrate (97%) from Aldrich Trigonox® B di-tert-butyl peroxide from Akzo Nobel DF-0 diesel # 2 with low sulfur content from Octel with a boiling range of 163-370 ° C, a vaporization point of 51.6-65.5 ° C (D-93), and a self-ignition temperature of 257 ° C (E-659).

Procedure The performance of the ignition improvers in the process according to the invention was evaluated by means of the following selection method: Mix the ignition improver in the specified amount with the diesel fuel at room temperature, Inject a 100 μl sample or 250 μl by means of a syringe in an apparatus in accordance with DIN 51794, which is controlled at a temperature of 270 ° C, and the time that passes before the sample is ignited is measured. Alternatively, the cetane number of the fuel is measured in accordance with ASTM method D-613. The active oxygen content of the peroxides and fuels was analyzed by conventional analytical techniques such as iodometric titration and gas chromatographic analysis. More specifically, the linear ketone peroxides were analyzed by means of a Jo / 97.3 method and the total amount of active oxygen was analyzed by method Jo / 97.2. The ratio of dimeric to trimeric ketone peroxide was analyzed by GC method 97.8. These methods are available upon request from Akzo Nobel. The predominantly trimeric methylisobutyl ketone cyclic peroxide to be used as a fuel additive was produced by adding 97.1 g of hydrogen peroxide (70%) to a stirred mixture of 200 g of methyl isobutyl ketone, 100 g of Isopar® M, and 196 g of sulfuric acid (50%) in the course of 20 minutes, under a temperature of 20-25 ° C. The mixture was then stirred for a further 3 hours at 40 ° C and for 18 hours at 30 ° C. The organic phase was separated, washed with water and caustic and sulphite solutions, respectively, and dried with magnesium sulfate dihydrate. This procedure resulted in 235 g of an organic liquid with a total active oxygen content of 2.14%, of which 2.07% was cyclic peroxide of methyl isobutyl ketone and less than 0.07% was linear peroxide of methyl isobutyl ketone. The ratio of dimeric to trimeric compounds was 12:88% GC area.

EXAMPLE 1 DFO diesel fuel was mixed with enough cyclic MEKP-1 to give a concentration of 1% w / w of cyclic ketone peroxide in the diesel fuel. Both samples, 100 μl and 250 μl, when tested as described above were turned on after 3.0 seconds. The cetane number of the fuel with improved ignition was greater than 73.7.

COMPARATIVE EXAMPLES A-D Example 1 was repeated, except that no other conventional ignition improver was used. The compounds used, their concentration in the diesel fuel and the results of the tests are incorporated in the following table. n.d = not determined Example B was repeated using 0.787% w / w of 2-EHN and diesel 2. The fuel with improved ignition (cetane number approximately 61) was evaluated in accordance with Conradson's ASTM-D189 test.

When converted to equivalent values for the Ramsbottom residue test, deposits of 0.2% w / w of carbon were formed.

COMPARATIVE EXAMPLES E-G Examples 1, 3 and 5 of document FR-862 974 were repeated as comparative examples E-G, respectively, except that Example 5 was not repeated in a continuous form but in discontinuous form. The dissolution and yield of the cyclic acetone peroxide of Comparative Example E in the fuel were not satisfactory. The cyclic butanone peroxides of comparative examples F and G contained 90 and 76% (GC area%) of butanone dimer peroxide and 10 and 24% (% GC area) of truncated butanone peroxide, based on the GC area of cyclic ketone peroxides.

EXAMPLES 2-7 AND COMPARATIVE EXAMPLES H-J Several ketone peroxides were evaluated for their influence on the cetane number, using 3 types of diesel fuel. In Examples 2-6 cyclic MEKP-2 was used as a fuel ignition improver, while in Example 7 the cyclic methyl isobutyl ketone peroxide prepared as indicated above was used. In Comparative Example H, ketone peroxide was not used, in Comparative Example I Butanox®M50 was used from Akzo Nobel, a predominantly linear methyl ethyl ketone peroxide, whereas in Comparative Example J Trigonox®233 was used from Akzo Nobel, a predominantly linear methyl isobutyl ketone peroxide. The diesel fuels that were used are characterized by the following: LCO = light cyclization oil The following results were obtained: n.d. = not determined Obviously, on an equal active oxygen base, the ketone cyclic peroxides of the higher ketones are more efficient to improve the cetane number. In addition, the product of example 6 in diesel 2 was evaluated in accordance with the Conradson test ASTM-D189. When converted to equivalent values for the Ramsbottom residue test, it was formed 0. 05% p / p of carbon deposits, which is much better than the result obtained in comparative example B.

EXAMPLE 8 A fuel according to the invention was prepared by adding 19.4 g of hydrogen peroxide to a stirred mixture of 27 g of diesel 1, 28.8 g of methyl ethyl ketone peroxide and 14.0 g of sulfuric acid in a period of 20 minutes, while the temperature it is maintained at approximately 20 ° C. The mixture was then stirred for a further 90 minutes at 20 ° C, and the two layers were separated. The organic layer was washed with 25 g of a 6% w / w solution of sodium bicarbonate, dried with magnesium sulfate dihydrate and filtered. The product contained predominantly cyclic methyl ethyl ketone peroxide with a ratio of dimeric / trimeric compounds of 13: 87% GC area.

EXAMPLE 9 AND COMPARATIVE EXAMPLE K In order to demonstrate the differences in the effect of the dimeric and trimeric cyclic peroxide peroxides when used as a fuel ignition improver, a diesel fuel with 0.595% w / w cyclic methyl ethyl ketone peroxide was contaminated. In Example 9, a product with a ratio of dimeric / trimeric compounds of 5.6: 94.4 (% GC area) was used, whereas in Comparative Example K this ratio was 98.6: 1.4 (% GC area). The cetane number of untreated fuel was 54.7. The cetane number of the fuel of example 9 was 69.3. The cetane number of the fuels of Comparative Example K was 64.7.

Claims (13)

NOVELTY OF THE INVENTION CLAIMS

1. - The fuel with improved ignition characteristics comprising one or more cyclic ketone peroxides, characterized in that it comprises from 0.01 to 10% by weight of one or more ketone cyclic peroxides selected from the group of peroxides represented by formula I: (Or where Ri, R3 and R5 are inddently selected from the group consisting of hydrogen, C? -C2o alkyl, C3-C2o cycloalkyl, C6-C20 aryl, C7-C20 aralkyl and C7-C20 alkaryl, groups may include linear or branched alkyl portions: R 2, R 4 and R 6 are inddently selected from the group consisting of hydrogen, C 2 -C 2 alkyl, C 3 -C 2 cycloalkyl, C 2 -C 20 aryl, C 7 -C 2 aralkyl, and C7-C2o alkaryl, which groups may include linear or branched alkyl portions, and each of R? -R6 may optionally be substituted with one or more groups selected from hydroxy, alkoxy, linear or branched alkyl, aryloxy, ester, carboxy, nitrile and amido, with the proviso that said peroxides constitute at least up to 35% by weight of all cyclic ketone peroxides in the fuel

2. A fuel according to claim 1, further characterized in that the concentration end of peroxide or (s) according to formula I of the fuel is between 0.025 and 5% by weight, based on the weight of the total formulation.

3. A fuel according to claim 1 or 2, characterized in that at least one of the ketone cyclic peroxides in the fuel is obtained from one or more ketones that are selected from the group consisting of acetone, methyl- n-amylketone, ethylbutyl ketone, ethylpropyl ketone, methylheptylketone, methylhexylketone, ethylamyl ketone, methylpropylketone, diethyl ketone, methyl ethyl ketone, isomers of these ketones and mixtures thereof.

4. A fuel according to claim 3, further characterized in that it comprises a cyclic ketone peroxide of the formula I obtained from at least one ketone selected from the group consisting of methyl-n-amyl ketone, ethyl butyl ketone, ethyl propyl ketone, methyl ethyl ketone. , methyl ethyl ketone, ethylamyl ketone, methyl propyl ketone, diethyl ketone, methyl ethyl ketone, and isomers thereof.

5. A fuel according to claim 4, further characterized in that the cyclic ketone peroxide of the formula I is obtained from a ketone selected from the group consisting of methylbutyl ketone, methyl-n-amylketone, ethylbutyl ketone, ethylpropyl ketone, methylheptyl ketone. , methyl ethyl ketone, ethylamyl ketone, methyl propyl ketone, diethyl ketone, methyl ethyl ketone, and isomers thereof.

6. A fuel according to any of claims 1-5, further characterized in that the amount of cyclic ketone peroxide of the formula I in the fuel is at least 40% by weight, preferably at least 50% by weight, and more preferred more than 80% by weight, based on the weight of all cyclic ketone peroxide in the fuel.

7. A fuel according to any of claims 1-6, further characterized in that the cyclic ketone peroxide of the formula I is selected from the group consisting of cyclic methyl ethyl ketone peroxide, cyclic methyl isobutyl ketone peroxide and cyclic methyl isopropyl ketone peroxide.

8. A fuel according to any of claims 1-7, further characterized in that the fuel is a diesel fuel.

9. The process for making an improved ignition fuel according to any of claims 1-8, characterized in that a cyclic ketone peroxide composition is combined with a fuel, whose cyclic ketone peroxide composition comprises at least 35 % by weight, based on the weight of all cyclic ketone peroxides, of one or more cyclic ketone peroxides which are selected from the peroxides represented by formula I and which further comprises one or more non-halogenated phlegmatizers selected from the group consists of hydrocarbons, oxygenated hydrocarbons, alkyl nitrates and mixtures thereof.

10. A method according to claim 9, further characterized in that the phlegmatizer used is selected from the group consisting of alkanols, cycloalkanols, alkylene glycols, monoalkyl ethers of alkenylene glycol, ethers, aldehydes, ketones, epoxies, esters, hydrocarbons, and mixtures thereof.

11. A method according to claim 10, further characterized in that the phlegmatizer is selected from ethers or hydrocarbons, preferably from hydrocarbon-based fuels such as diesel fuels.

12. A process for making an improved ignition fuel according to any of claims 1-8, further characterized in that the cyclic ketone peroxide is produced at the specified concentration in the fuel.

13. The use of a fuel according to any of claims 1-8 in a combustion engine to reduce the emission of pollutants.