US2136456A - Diesel fuel - Google Patents

Description

Patented Nov. 15, 1938 UNITED STATES v PATENT OFFICE N. 1., assignors toSocony-Vacuum ()il Com- D ni, Incorporated, New York, N. Y., a corporation of New York No Drawing.

Application September 15, 1937,

Serial No. 103,912

12Claims.

This invention has to do in a general way with fuels for internal combustion engines of the Diesel type and is more particularly concerned with the modification of such fuels by the addition of characterizing ingredients for the purpose of modifyirfg or controlling the combustion characteristics. a

In the Diesel cycle internal combustion engine where the fuel is injected into a combustion space it is important, to the attainment of maximum efficiency, that the delay period between injection and ignition be short. It will thus be seen that enhanced speed of ignition is a characteristie that is highly desirable. Improperly delayed ignition in a Diesel engine gives rise to the phenomena known as knocking, due to improper coordination of combustion and cylinder conditions. By accelerating the ignition, point of Diesel fuel it is possible to lower the compression pressure which will insure spontaneous ignition without combustion shock, thereby increasing the ease of starting and the smoothness with which combustion takes place. In this same connection, the low compression pressure permits of a lower weight in the engine and a lower cost per given power output.

It has been found that the ignition quality of a fuel oil can be improved by the addition of small amounts of certain compounds which act as ignition accelerators. This offers a means for improving the better grades of Diesel fuels and a means of widening the range of available fuels by raising the ignition quality of lower grades to a point where they canbe satisfactorily used. 3a ,A number of compounds have been proposed as ignition accelerators for Diesel fuels. Among such compounds are such materials asethyl nitrate, amyl nitrite, and peroxides. Many of these compounds are unsatisfactory 40 from the standpoint of stability, cost, toxicity, or because of their tendency to formcorrosive gases in the combustion chamber, of the engine.

Our present invention is directed to Diesel type fuels which have been improved: in ignition 45 quality by the addition of novel compounds which promote rapidity of combustion and so give the desired control to the combustion characteristics of the fuel.

By the term Diesel type fuels or Diesel fuel" 50 as it is used herein we have reference not only to the distillates of the kerosene-like boiling range commonly denoted as Diesel fuel, but we intend to include, as well, the general field of hydrocarbon products, both heavier and lighter than the fuel above referred to, such, forvexample, as the light or heavy fuel oils and gasoline for use in Diesel cycle engines.

In our co-pending application, Serial Number 95,422, filed August 11, 1936, and entitled "Diesel 60 fuel, we have disclosed fuel which has been improved by mixing therewith a minor proportion of diazo-amino' benzene, which is diphenyl triazene, having the formula c.mr IN=N-'-c.fi= H We have now discovered that the general class -of compounds known as triazenes possesses the in which R, R, and R" represent hydrocarbon radicals or substituted hydrocarbon radicals, in which R or.R" may be replaced with hydrogen,

or in which R. and R may represent the hydro- 30 carbon portion of a heterocyclic compound containing .a nitrogen atom as, for example, in the piperidide compounds.

The compounds of this group. used in the tests conducted by us which have demonstrated the value of the group as an lmprover for Diesel fuel, may be broadly classified as the products obtained by the condensation of a diazotized aromatic amine and an amine selected from the class' including primary aryl am nes, secondary aryl amines, secondary alkyl-amines, and secondary alkyl-aryl amines. These triazenes may be d vided into the following sub-classes. which are listed with examples and probable structural formulae .and references to the literature for a 45 method which may be used in their preparation.

(1) Symmetrical diaryl triazenes:

(a) Diphenyl trlazene (diazo amino benzene) Organic Syntheses Vol. XIV p. 24 (Wiley 1934) (b) Di-p-tolyl trlazene H Mehner, J. prakt. Chem. (2) 65, 42': i (1902) I (2) Unsymmetrical triazenes:

(a) Phenyl, pqtolyl triazene Noelting and Binder Ber. 20, 3005 (1887). (b) 4 chloro, 4' methyl diphenyl triazene Medola and Streatfleld, J. Chem. Soc. 55, 437 (1889); 57, 790 (1890). Goldschmidt and Bax-dash, Ber. 25, 1363 (1892). (3) Trisubstituted triazenes Ethyl diphenyl triazene Gill Vignon and Simonet Compt'rend.

(b) Phenyl diamyl triazene CHn Same method as 3a. (0) 1, 1 pentamethylene 3 p-tolyl triazene (p-toluene diazo piperidide) 0-0 a H1 H3 Wallach Ann. 235, 245 (1886) The following general method may be employed in preparing any or all of the triazenes falling into'the 3 general classifications set forth above (the examples given being merely illustrative) A primary aromatic amine is diazotized by any of the well known methods, such as by adding sodium nitrite to an aqueous acid solution of the amine at reduced temperature (0-20 0.). This freshly prepared solution of diazonium salt is then combined with a suspension of an amine (primary or secondary, selected from the'class or group indicated above) in a water solution of a salt capable of maintaining the solution neutralor slightly basic, such, for example, as a sodium acetate or an alkali carbonte solution, at reduced temperature. The precipitated triazene is washed thoroughly with water and may be recrystallized rapidly from a hot hydrocarbon solvent, such as ligroin or Btoddard's solvent.

Slight modifications in the general procedure outlined above are made to accommodate certain particular characteristics of the reactants; depending on the product sought.

For example, in making symmetrical diaryl triazenes it will be seen that the amine which is condensed with the diazonium salt is the same as the one diazotized, so'that in this case two molecular weights of the amine are added and sumcient nitrite is used to diazotize one molecular weight. Condensation is then effected by neutralization.

In the case of the trisubstituted triazenes the primary aromatic amine is diazontized and coupled with a secondary amine.-

The pentamethylene 3-p-tolyl triazene (p-toluas an unsymmetrical triazene or as a trisubstituted triazene, but since the two bonds of the secondary nitrogen are both linked to the hydrocarbon grouping, compounds of this type are perliaps more logically classified as the trisubstituted triazenw. Furthermore, forpurposes of nomenclature herein, saturated cyclic hydrocarbon radicals of the pentamethylene type will be considcharacteristics as the sample being tested. (Proc.

Am. Soc. Testing Materials vol. 36, I p. 418) An increase in cetane number indicates a decrease in delay between fuel injection and fuel ignition,

and consequently indicates aniimprovement in fuel combustion characteristics.

As examples of the improved efliciency obtained through the use of the class of additive ingredients contemplated herein, we have indicated in the following table the results of a plurality of tests in whichthe increase in cetane number derived through" various percentages of added ingredients were obtained. The base fuel used in these tests was a petroleum distillate commonly known as Number 2 Fuel Oil, having a flash point of 160 F., specific gravity of .8478, and Lovibond color of 0.7. The cetane number of the unblended base stock was 50, and it is clearly apparent from the table, that compounds characterized by the presence of the triazene nucleus all eifect a material increase in cetane number.

Concen. Cetane Increase Compound added wt. pernumber in cetane centage of blend number Phenyl diamyl triasene l. 0 65. 0 5. 0 Ethg diphenyl triaune" 0. 6 56. 6 6. 6 o. 1. 0 66. 6 6. 6 2. 0 67. 0 7. 0 0. 6 63. 6 3. 6 l. 0 69. 0 9. 0 2. 0 63. 0 l3. 0 0. 2 63. 6 3. 6 0. 6 64. 0 4. 0 1. 0 66. 0 6. 0 2. 0 66. 0 6. 0 0. 2 63. 0 3. 0 0. 6 66. 0 6. 0 l. 0 66. 0 6. i) 2. 0 66. 0 6. 0

Triazene compounds of the general class exemplifled by the foregoing examples may be used in amounts varying with the extent to which it is desired to improve the fuel. They may be used individually or in mixtures of two or more and in proportions up to about 5.0% of the fuel. In general, however, lower concentrations are preferred, and a concentration in the neighborhood of 1.0% is believed to be sufllcient for most purposes.

In the-following claims the terms "Diesel fuel-',

hydrocarbon fuel oil", and mineral hydrocarbon fuel include any and all types of hydrocarbon products intended for use in any engine operating according to the Diesel cycle.

We claim:

1. An improved Diesel fuel composition comprising: a hydrocarbon fuel oil and in admixture therewith a minor proportion of atriazene which is characterized by the presence of at least one aryl nucleus, said triazene comprising a suiiicient proportion of the composition as a whole to decrease the ignition delay period of the fuel.

2. An improved Diesel fuel composition com-- prising: a hydrocarbon fuel oil and in admixture therewith a minor proportion, sufficient to decrease the ignition delay. period of the fuel, of a crease the ignition delay period-of the fuel, of a tri-substituted aryl-alkyl .triazene.

5. An improved Diesel fuel comprising: a hydrocarbon fuel oil and in admixture therewith a minor proportion of a compound having the prob.-

able formula:

in which R represents an aryl radical or a substituted aryl radical and R and R' represent hydrocarbon radicals or the hydrocarbon portion of a heterocyclic radical containing a nitrogen atom, said compound being present in an amountsuflicient todecrease the ignition delay period of the fuel.

6. An improved Diesel fuel comprising: a hydrocarbon fuel oil and in admixture therewith a minor proportionofa compound having the probable formula in which R represents an aryl radical or a substituted aryl radical and R and R', represent hydrocarbon radicals or substituted hydrocarbon radicals, one of which may be replaced withhydrogen, said compound being present in an amount sufficient to decreasethe ignition delay period of the fuel.

'7. An improved Diesel fuel comprising: a hydrocarbon fuel oiland in admixture therewith a minor" proportion .of a compound having thestituted aryl radical and R and R" represent aryl or alkyl radicals, one of which may be replaced with hydrogen, said compound being pres- 'ent in an amount sufficient to decrease the ignition delay period of the fuel.

8. An improved Diesel fuel comprising: a mineral hydrocarbon fuel and in admixture therewith a minor proportion of a compound obtained by the condensation of a diazotized aromatic amino with an amine selected from the group consisting of primary aryl amines, secondary aryl amines,

secondary alkyl amines and secondary aryl-alkyl amines, said compound being present in an amount sufficient to decrease the ignition delay period of the fuel. 1

9. An improved Diesel fuel comprising: a min? period of the fuel.

10. An'improved Diesel fuel comprising: a mineral hydrocarbon fuel and in admixture therewith a minor proportion of an aryl-alkyl triazene in amount sufficient to decrease the ignition delay period of the fuel.

11. An improved Diesel fuel comprising: a min:- eral hydrocarbon oil and in admixture therewith a minor proportion of one'or more substituted triazenesselected from the group consisting of di-p-tolyl triazene; phenyl, p-tolyl triazene; methyl, chloro diphenyl triazene; ethyl diphenyl triazene; phenyl diamyl triazeneand pentamethylene p-tolyl .triazene, said triazene being present in an amount sufflcient to decrease the ignition delay periodof the fuel.

12. The method of improving the combustion characteristics of 9. Diesel fuel which includes admixing a small proportion of aryl triazene therewith. ROBERT C. MORAN EVERETT W. FULLER GEORGE S. CRANDALL.