US2692195A - Nitroparaffin fuel - Google Patents

Description

Patented Oct. 19, 1954 UNITED STATES PATENT OFFICE NITROPARAFFIN FUEL John A. Hannum and Joseph N. Epel, Detroit,

Mich., assignors, by mesne assignments, to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois No Drawing. Application September 4, 1947, Serial No. 772,220

devices, although they may also be efficiently used for other prime movers under a variety of circumstances as in aircraft, underwater craft, land vehicles and stationary installations. Furthermore these materials may be used as a source of powerfor particular types of devices such as rockets, ram-jets and the like.

Under many operating conditions it is desirable to thermally stabilize the fuel, as by providing a catalyst to improve its combustion characteristics. have been used as catalysts to aid the fuel combustion but, unfortunately, they also act to some 'extent to lower the normal explosion temperatures of the material, making it less safe to handle and more liable to premature combustion or explosion than it was before addition of the catalyst. So far as is known, such additives have not heretofore been used with this class of materials without rendering them materially less useful as fuels.

A general object of the present invention is to provide an improved fuel of this kind. Another object is to provide an additive for use with fuels, particularly nitro aliphatic fuels, by which their tendency to explode prematurely in consequence of the addition of the catalyst is decreased and the safety with which they may be handled improved. Still another object is to provide an additive that acts as a catalyst to a fuel to im- Heretofore certain fuel additives.

prove its operating characteristics, as by enabling adapted for use with the fuels that are disclosed in the copending application and that are in the form of liquid nitro aliphatic hydrocarbons, the terms nitro aliphatic and nitroparaffin as hereinafter used being construed herein to include both mono and polynitro derivatives. Such fuels are limited to those that contain not more than one nitro group for each carbon atom present. A preferred form of such fuel is nitromethane,

CH3(NO2), that itself contains much of the oxygen required during the combustion of the fuel elements in it. It is contemplated that other fuels from the class of nitro aliphatic liquids may be used in the present invention.

Examples of such fuels, in addition to nitromethane, are:

Nitroethane CH3.CH2.NO2 l -nitro pro pane CH3 .CH2.C'H2.NO2

Z-nitropropane CH3) 2CH.NO2 1,1 dinitropropane 2,2 -dinitropropane CH3) 20 (N02) 2 1 ,2dinitropropane CHzNOz .CHNO2. CH3 l,3-dinitropropane CH2NO2.CH2 .CHzNOz l ,l -dinitroethane CHxCH (N 02) 2 1,2,3-trinitropropane CH2NO2.CHNO2.CH2NO2 1,1, l-trinitropropane C (N02) 3 .CHzCHs Such nitro aliphatics included as fuels within the scope of this invention include mononitromethane, dinitroethane and trinitropropane and those nitroethanes and nitropropanes below them in oxygen content but no nitroethanes or nitropropanes that are higher in oxygen content, as for instance dinitromethane. These are all to be distinguished from aromatic fuels such as the nitrobenzo-ls that are dangerous to handle even by skilled persons to say nothing of persons who are not skilled in this art.

An advantage of using nitromethane or a similar partially nitrated aliphatic hydrocarbon as listed above resides in the fact that it contains a considerable proportion of the oxygen that is required during combustion to burn the carbon or hydrogen in the fuel. This in turn does not require the presence of as much air or other oxidizing agent as would otherwise be necessary. These fuel components are non-brisant nitro aliphatic compounds, non-brisant within the terms of this disclosure meaning that the fuel may be burned in contact with chilled iron without producing the Munroe efiect.

Although such fuels are non-brisant as defined above, it frequently is desirable to modify their explosion characteristics. When pure nitromethane is heated, it has a threshold explosion temperature of 593.6 Fahrenheit. As indicated above, the addition of certain materials serves to depress to some extent the normal explosion temperatures of pure nitromethane. Insofar as is known, no additive has been available until the present invention that modifies the explosion characteristics of nitromethane by suppressing its tendency to explode at or even below its normal explosion temperatures and still preserves and improves the desirable properties of nitromethane as a fuel.

The addition of a small amount, from a trace to substantially two percent by weight of the total fuel mixture, of a chemical compound which may be defined as including an atom of an element with predominantly metallic properties (metalloid), a plurality of oxygen atoms, and a polysubstituted amine radical both improves the combustion qualities of the fuels outlined above and modifies their explosion characteristics in the respect mentioned. Generally speaking, it has been found that chromium and uranium are the two most important metalloids insofar as the present invention is concerned, but work to date indicates that tungsten and molybdenum may also be used. As examples of the utility of the herein described invention, it is pointed out that when approximately 1% by weight of the pyridine salt of uranyl acetylacetonate is added to nitromethane, there is found to be an accompanying suppression of the tendency to explode at temperatures below 615.1 Fahrenheit, an increase of approximately 20 degrees over the threshold explosion temperature. In the same way when one percent by weight of dicyclohexylamine chromate is added to nitromethane, the corresponding value is found to be 691.7 Fahrenheit, an increase of about one hundred degrees.

Certain chromium-bearing catalysts have heretofore been added as previously mentioned to fuels of the type described, particularly nitromethane, to improve combustion. The materials comprehended by the present invention, particularly the .alkyl amine chromates and dichromates, are known to function as catalysts, dicyclohexylamine chromate serving the double purpose of acting as a catalyst of combustion and also significantly modifying the explosion characteristics of the fuel. In addition to the thermal stabilizers named above, various materials in the form of chromate or dichromate salts derived from reaction of chromic acid with aliphatic and alicyclie amines may be used in a percentage by weight varying from a trace to substantially 2% of the total fuel mixture to produce stabilizing results within the terms of this invention.

It is important that such salts be relatively stable in the fuels to which they are added and do not readily break down except incident to the process of combustion. For instance octadecylamine dichromate, hexadecylamine dichromate and hexylamine dichromate all break down in time in nitromethane, somewhat less in nitroethane, and are relatively stable in nitropropane, particularly in the absence of light. The effect of light on all these materials is important and it is desirable to store them in the absence of light, particularly if the storage period is of appreciable duration. Chromate and dichromate salts deemed within the scope of the present invention as stabilizer additives to fuels, in addition to pyridine salt of uranyl acetylacetonate, form a group as follows:

Hexyl, amine chromate or dichromate Cyclohexyl, amine chromate or dichromate 4 Octyl, amine chromate or dichromate Decyl, amine chromate or dichromate Dodecyl, amine chromate or dichromate Dicyclohexyl, amine chromate or dichromate Tetradecyl, amine chromate or dichromate Hexadecyl, amine chromate or dichromate Octadecyl, amine chromate or dichromate A fuel mixture made up in accord with the present invention will include one or more of the fuels listed above to make up more than 98 percent but less than 100 percent by weight of the whole. From two percent to a trace by weight will be made up of one or more of the stabilizers described herein. Within the limitations described above as to the absence of light and the relatively prompt use after preparation, these materials will act in varying degrees to stabilize the various nitro aliphatic fuels listed above, which they do by modifying their explosion characteristics; furthermore, inasmuch as they break down incident to the process of combustion of the fuel to yield finely. divided metallic oxides, they act as catalysts causing the fuel to burn steadily and quietly, as distinguished from intermittently, in the combustion zone.

The use for these purposes of certain of these compounds is claimed specifically in a divisional application filed in the name of John A I-Iannum on June 9, 1949, under Serial Number 98,157.

We claim:

.1. A fuel mixture comprising at least one liquid nitroparaffin containing not more than one nitro radical for each carbon atom but presenting nevertheless the danger of explosion arising out of an inherent capacity for thermal detonation;

the same being selected from a group consisting ,dinitroethane, 1,2,3 trinitropropane, and 1,1,1

trinitropropane, and mixtures thereof, to which has been added a suppressant comprising a saltlike organic compound including an atom of an element with predominantly metallic properties falling in sub-group A of group VI of the periodic table of elements, a plurality of oxygen atoms connected thereto, and a hydrocarbon-substituted amine radical which salt-like organic compound breaks down incident to the process of combustion to yield a finely-divided metallic oxide in the combustion zone.

2. A fuel mixture comprising at least one liquid nitroparafiin containing not more than one nitro radical for each carbon atom but presenting nevertheless the danger of explosion arising out of an inherent capacity for thermal detonation; the same being selected from a group consisting of nitromethane, nitroethane, l-nitropropane, 2- nitropropa-ne, 1,1 dinitropropane, 2,2 dinitropropane, 1,2 dinitropropane, 1,3 dinitropropane, 1,1 dinitroethane, 1,2,3 trinitropropane, and 1,1,1 trinitropropane, and mixtures thereof, to which has been added a suppressant modifying the explosion characteristics of the nitroparafiin component, said suppressant comprising an aliphatic amine chromate.

3. A fuel mixture comprising at least one liquid nitroparaffin containing not more than one nitro radical for each carbon atom but presenting nevertheless the danger of explosion arising out of an inherent capacity for thermal detonation; the same being selected from a group consisting of nitromethane, nitroethane, l-nitropropane, 2- nitropropane, 1,1 dinitropropane, 2,2 dinitropropane, 1,2 dinitropropane, 1,3 dinitropropane,. 1,1

5 dinitroethane, 1,2,3 trinitropropane, and 1,1,1 trinitropropane, and mixtures thereof, to which has been added a suppressant modifying the explosion characteristics of the nitroparamn component, said suppressant comprising a dicyclohexyl amine chromate.

4. A fuel mixture as in claim 3 comprising mononitromethane and dicyclohexyl amine chromate in the proportions of more than 98% of the former and less than 2%, but more than a trace, of the latter.

5. A fuel mixture as in claim 3 comprising mononitroethane and dicyclohexyl amine chr0- mate in the proportions of more than 98% of the former and less than 2%, but more than a trace, of the latter.

6 References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Journal Inst. of Pet. Tech., vol. 1319'27, page 281, article by Egerton et al.

Claims (1)

1. A FUEL MIXTURE COMPRISING AT LEAST ONE LIQUID NITROPARAFFIN CONTAINING NOT MORE THAN ONE NITRO RADICAL FOR EACH CARBON ATOM BUT PRESENTING NEVERTHELESS THE DANGER OF EXPLOSION ARISING OUT OF AN INHERENT CAPACITY FOR THERMAL DETONATION; THE SAME BEING SELECTED FROM A GROUP CONSISTING OF NITROMETHANE, NITROETHANE,1-NITROPROPANE, 2NITROPROPANE, 1,1 DINITROPROPANE, 2,2 DINITROPROPANE, 1,2 DINITROPROPANE, 1,3 DINITROPROPANE, 1,1 DINITROETHANE, 1,2,3 TRINITROPROPANE, AND 1,1,1 TRINITROPROPANE, AND MIXTURES THEREOF, TO WHICH HAS BEEN ADDED A SUPPRESSANT COMPRISING A SALTLIKE ORGANIC COMPOUND INCLUDING AN ATOM OF AN ELEMENT WITH PREDOMINANTLY METALLIC PROPERTIES FALLING IN SUB-GROUP A OF GROUP VI OF THE PERIODIC TABLE OF ELEMENTS, A PLURALITY OF OXYGEN ATOMS CONNECTED THERETO, AND A HYDROCARBON-SUBSTITUTED AMINE RADICAL WHICH SALT-LIKE ORGANIC COMPOUND BREAKS DOWN INCIDENT TO THE PROCESS OF COMBUSTION TO YIELD A FINELY-DIVIDED METALLIC OXIDE IN THE COMBUSTION ZONE.