US2240145A - Motor fuel composition - Google Patents

Description

Patented Apr. 29, 1941 MOTOR FUEL COMPOSITION I Franz Rudolf Moser, Amsterdam, Netherlands,

assignor to Shell Development Company, San

Francisco, Calif., a corporation of Delaware No Drawing. Application August 22, 1939, Serial No. 291,361. In the Netherlands December 2,

6 Claims.

This invention relates to a liquid fuel composition for internal combustion engines with fuel injection at the end of the compression stroke, and is more specifically concerned with liquid diesel fuels containing ketone peroxides. This invention is an improvement over that disclosed in my Patent No. 2,011,297 and in my application Serial No. 181,151 filed December 22, 1937.

In the operation of compression ignition engines of the Diesel and semi-Diesel types, and especially in the case of the high speed engines of these types, the relatively long period of time which may elapse between the injection and the ignition of the fuel causes rough running of the engine.

It is known that the ignition properties of Diesel fuels as expressed by their cetane numbers, can be considerably" improved by the addition thereto of a small quantity of a ketone or an aldehyde peroxide such as acetone peroxide, methyl ethyl 20 ketone peroxide, etc. Ketone or aldehyde peroxides may be prepared by various reactions, for example by allowing H202 to act upon a ketone. or an aldehyde in anacid medium such as dilute sulfuric acid or by oxidizing the ketone or aldehyde with a solution of persulfuric acid hydrolyzed by a brief heating. -Peroxides so obtained are chiefly in the dimeric or trimeric form, and while they are very eifective in increasing the octane number of Diesel fuels, they have the disadvantages of being solid at normal room tem,

peratures, having fairly high melting points, and also being in general relatively little soluble in Diesel fuels of the gas oil type.v These disadvantages make diflicult the production of ooncen-- trates of the peroxides in hydrocarbon oils, concentrates being important for the economical and safe transportation of the peroxides which are .too explosive to be shipped without diluents, and for the greater ease in apportioning these compounds with conventional types of blending equipment.

Now I have found that normally liq'uid peroxides having solubilities in the ordinary gas oil type of Diesel fuel much higher than those of ketone be produced by the oxidation of mixtures of at least 2 aliphatic ketones having different numbers of carbon atoms which mixtures preferably have an average number of carbon atoms of not 50 more than 8, and the highest'number of carbon atoms of any member preferablybeing not more than 12. This rather unexpected result is believed to be due to the formation of heteroand aldehyde peroxides heretofore known may mere depression of the melting point caused by mixing different homopolymeric peroxides, the asymmetry of the heteropolymeric peroxides apparently accounting for the great difference in physical properties.

The heteropolymeric ketone peroxides are c0- dimers and co-trimers and appear to have polymerized structures similar to those of the homopolymeric compounds, in other words they are composed of at least two constituentketone peroxides which constituents have different numbers of carbon atoms. Thus they may be built up of, either 2 ketone peroxides having different numbers of carbon atoms; or of 3 ketone peroxides, two of which have the same number of carbon atoms, the third having a different number of carbon atoms; .or of three ketone peroxides all of which have different numbers of carbon atoms. The heteropolymeric peroxides generally have very low melting points which are below 0 0., are only slightly volatile, and are miscible with most Diesel fuels such as gas oil, solar oil, Edeleanu kerosene raflinate or extract, heavy pressure distillate and coal tar fractions, inall proportions. These peroxides are furthermore at least as stable as the homopolymeric peroxides, and also are frequently slightly more effective in increasing the cetane numbers of Diesel fuels than are the homopolymeric peroxides of equal average numbers of carbon atoms. In general, the peroxides built up of ketones having relatively few carbon atoms are somewhat more effective than the peroxides built up of higher-ketones,

and those peroxides are the most effective which contain acetone as part of the molecule, 1; e. are produced of mixtures of acetone and other ketones having from 4 to 12 carbon atoms, the content of the higher ketones in the mixture being preferably from to 2% mols per mol of acetone.

The heteropolymeric peroxides may be produced by oxidation in a manner similar to the production of homopolymeric peroxides. Thus a suitable mixture of ketones may be oxidized with H2O: in acid solution either in the absence or presence of a solvent for the peroxides which is substantially resistant to attack of the oxidizing agent. If desired, the fuel itself may be used for the solvent so that the resulting products are concentrates which may be directly blended with fuels or be stored or shipped. The structure of the individual heteropolymeric ketone peroxides, their tendency preferentially to form dimers or trimers respectively, the relative proportions of different heteropolymeric ketone peroxides or polymeric ketone peroxides rather than to the 5 homopolymeric ketone peroxides in the product and on the magnitude of the effect which it is desired to produce. In general, small quantities of 5% or less and more often of the order of 0.1 to 2% are sufllcient since these peroxides are very eflicient in improving cetane numbers of Diesel fuels, being as before stated generally even more effective than the homopolymeric peroxides.

Example A heteropolymeric ketone peroxide mixture was prepared by oxidation of a mixture of 36 gm. of butanone and 29 gms. of acetone with H2O: in sulfuric acid at a. temperature not exceeding 0 C.

On addition of 1% of this heteropolymeric ketone peroxide to a Diesel fuel the cetane number was increased from 41 to 56. Addition of 1% of trimeric acetone peroxide or of 1% butanone peroxide increased the cetane number of the same fuel only to 53.

Aliphatic heteropolymeric ketone peroxides are particularly useful for Diesel fuel dopes. ever, if desired, ketone mixtures from which the peroxides are obtained may comprise one or more components which contain one aryl, aralkyl or alicyclic radical.

How-

I claim as my invention:

1. A liquid fuel for compression ignition engines containing a small amount of heteropolymeric ketone peroxides obtained by oxidizing a mixture of at least 2 ketones of different molecular sizes one of which is acetone, said mixture having an average number of carbon atoms of not more than 8, the highest number of carbon atoms of any one ketone in said mixture being not more than 12, and the mixtures containing not more than mol of any one ketone.

2. A liquid fuel for compression ignition engines containing a small amount of heteropolymeric ketone peroxides obtained by oxidizing a mixture of acetone and at least one other ketone having 4 to 12 carbon atoms.

3. A liquid fuel for compression ignition engines containing a small amount of heteropolymeric ketone peroxide obtained by oxidizing a mixture of acetone and at least one other ketone having 4 to 12 carbon atoms, the mol ratio of the ketones other than acetone to acetone in said mixture being from /4, to 2%.

4. A liquid fuel for compression ignition engines containing a small amount of a heteropolymeric ketone peroxide having 2 or 3 different constituent ketone peroxides at least one of which constituents is acetone peroxide. 1

5. The composition of claim 2 in which the amount of the ketone peroxide is less than 5%.

6. The composition of claim 2 in which the amount of the heteropolymeric ketone peroxide is between the limits of .1 to 2%.

FRANZ RUDOLF MOSER.