Methanol automotive fuel

Description

Background of the invention

[0001] With the world's supply of petroleum diminishing, much emphasis has been placed on finding substitutes for fuels such as gasoline which are derived from petroleum. For example, a combination of gasoline and ethyl alcohol sometimes called "gasohol" has been widely heralded because it lowers the amount of gasoline required to run an internal combustion engine. Of course, gasohol contains a large amount of gasoline (90%). It would, of course, be desirable to find a substitute for gasoline which does not employ any petroleum derivatives at all. The use of straight ethanol as an engine fuel has been explored. This approach, however, suffers from a number of deficiencies, one of which is that the principal source of ethanol is grain which would otherwise be directed to food products. Of course, if the efficiency of ethanol could be improved, its use would be more attractive.

[0002] It would, of course, be highly desirable to utilize coal as a fuel for powering automobiles and other vehicles. One method suggested for utilizing coal as a fuel for internal combustion engines involves converting the coal to methanol. A suggested use for methanol is to add it to gasoline to make a fuel similar to gasohol. As an additive or extender for gasoline, methanol could fulfill a function similar to that of ethanol; but, adding methanol to gasoline presents problems. If even a small quantity of water gets into an automobile tank, a methanol-gasoline blend will separate. The methanol and water fall to the bottom of the tank, get into the engine and stall it.

[0003] The use of straight methanol as a fuel has been suggested. With minor modifications to the engine, such as raising the engine's compression ratio and adding a heating system for cold starts, an automobile can run on straight methanol. However, methanol produces only about half the calories per volume unit as conventional gasoline. In connection with the foregoing, the heat of combustion figures for gasoline and methanol appear below:

Gasoline: 43,96 kj/g (10.5 kilocalories per gram)

Methanol: 19,68 kj/g (4.7 kilocalories per gram)

[0004] The significance of the foregoing is that studies anticipate that the price at the plant gate for converting coal to methanol is about 55-65% of the retail price of gasoline. Thus, unless the combustion characteristics of methanol is somehow improved, it would not be competitive with gasoline as it is presently priced. It would, of course, be highly desirable to increase the combustion characteristics of methanol so that it would be economical to use methanol as a substitute for gasoline. Of course, it should also be noted that in addition to producing methanol synthetically from coal, it can also be produced from forest and farm wastes such as wood chips, garbage, plant stocks and manure.

Summary of the invention

[0005] In accordance with the present invention, the properties of methanol and ethanol (or other lower alcohols) as a fuel for an internal combustion engine are greatly improved by an additive which is a tertiary alkyl peroxide. Accordingly, an object of the present invention is to provide a methanol or ethanol (and other lower alcohols) based fuel which can be utilized as a substitute in whole or in part for gasoline as a fuel for an internal combustion engine. A further object of the present invention is to provide a method of powering an internal combustion engine by burning such fuel.

Brief description of the drawing

[0006] The sole figure of the drawing is a graph showing increase in km/I (miles per gallon) versus percent of DTBP by volume.

Description of the preferred embodiments

[0007] At the outset, the present invention is described in its broadest overall aspects with a more detailed description following. The fuel and the method of powering internal combustion engines are both defined in the claims. In its broadest overall aspect, the present invention is a fuel composition for an internal combustion engine and a method of powering an internal combustion engine. The fuel composition includes methanol or ethanol or other lower alcohols and an additive. The fuel composition may be utilized directly as a fuel for a typical gasoline engine or it may be mixed with gasoline for use in such engines. When methanol issues its content amounts to at least 42.5% by volume.

[0008] The additive itself is a tertiary alkyl peroxide. The preferred tertiary alkyl peroxide is a ditertiary alkyl peroxide of the general formula:

where R₁ through R₆ are lower alkyl radicals.

[0009] The most preferred additive is di-t-butyl peroxide of the formula:

[0010] Tertiary alkyl hydroperoxides having the following formula may also be used:

where R₁ to R₃ are lower alkyl radicals.

[0011] The preferred alkyl hydroperoxide is t-butyl hydroperoxide of the formula:

[0012] In accordance with the present invention, it has been discovered that an appropriate mixture of tertiary alkyl peroxides and methanol produces a fuel composition which burns with approximately double the efficiency of straight methanol giving approximately the same miles per gallon as gasoline. However, this fuel composition has combustion characteristics which can produce auto-ignition and accompanying knocking in a conventional gasoline engine. This problem of course, can be overcome by engine design. However, to overcome this problem with existing engines, it has been discovered that a quantity of water and isopropanol when added to the fuel composition results in a fuel that can be substituted for conventional petroleum fuels or mixed with them as an extender without producing auto-ignition or knocking. Furthermore, the isopropanol reduces problems associated with water-methanol mixtures.

[0013] Tests with methanol also indicate that the tertiary alkyl peroxide additives will improve the performance of straight ethanol and gasohol.

[0014] Thus, the fuel composition of the present invention is a mixture of methanol and/or ethanol and a tertiary alkyl peroxide, but may contain additives to improve the overall characteristics and performance of the fuel, in the case of methanol its content amounts to at least 42.5% by volume.

[0015] The use of peroxides as additives for fuel has been suggested. For example, U.S. Patent No. 1,766,501 to Buerk entitled "Liquid Combustible" discloses adding peroxides in general to improve the combustion effect of gasoline.

[0016] U.S. Patent No. 3,108,864 to Barusch entitled "Engine Starting Fluid" describes the mixture of large quantities of dimethyl peroxide with diethyl ether as a starting primer for gasoline engines under sub-freezing conditions.

[0017] U.S. Patent Nos. 2,011,297 to Moser entitled "Process for Preparing Motor Fuel"; 2,092,322 to Moser entitled "Process for the Production of Organic Peroxides"; 2,093,008 to Egerton entitled "Fuel for Internal Combustion Engines"; 2,107,059 to Moser entitled "Motor Fuel Composition"; 2,174,680 to Badertscher et al. entitled "Diesel Fuel"; 2,240,145 to Moser entitled "Motor Fuel Composition" and 2,891,851 to Bailey et al. entitled "Fuel for Internal Combustion Engines" disclose the use of peroxides as additives to diesel fuels.

[0018] U.S. Patent No. 2,696,806 to Mingle, Jr. entitled "Removal of Combustion Chamber Deposits in Spark-Ignition Engines" discloses adding a peroxide to a fuel for removing deposits in spark-ignition engines.

[0019] U.S. Patent No. 3,869,262 to Mayerhoffer et al. entitled "Fuel and Additive for the Production Thereof" is illustrative of a large number of patents disclosing the use of isopropanol in gasoline.

[0020] US-A-4 045 188 discloses an additive for hydrocarbon motor fuels, which is added to a conventional gasoline in exceptionally small concentrations that is in concentrations of about 100 to 250 ppm (100 to 250 mg/I or 0,01 to 0,025 % by weight). This additive consists of a small amount of ditertiary butyl peroxide along with a solvent comprising ditertiary butyl alcohol (presumably tertiary butyl alochol) and either isopropanol or benzene as solid point depressant (the solidification point of pure tertiary butyl alcohol is 25,5°C=77°F).

[0021] It is stated that the mileage performance falls below that obtained without additive when the peroxide is present in amounts greater than about 2,5 ppm (0,00025 % by weight).

[0022] US-A-4 294 999 discloses the preparation of a complex mixture of tertiary butyl alcohol (TBA), tertiary butyl hydroperoxide (TBHP), methanol, acetone and other oxygen containing compounds from an isobutane charge.

[0023] Before the obtained mixture is blended with a hydrocarbon or gasoline it is treated to destroy residual THBP since it is said that the octane rating and the motor fuel performance of TBA is significantly impaired by the presence of even relatively small amounts of THBP. The THBP is destroyed in a decomposition zone and a subsequent cleanup procedure.

[0024] FR-A-775 851 discloses a fuel for use in an internal combustion engine comprising a mixture of methanol and/or ethanol with an alkyl peroxide, namely diethyl peroxide, and optionally gasoline. FR-A- does not disclose using di- tertiary alkyl peroxide or TBHP instead of the disclosed primary alkyl peroxide.

[0025] In accordance with the present invention, the fuel composition preferably contains about 1.5-6% peroxide with the balance being substantially methanol. As used throughout this specification and claims, all percentages are by volume at room temperature unless otherwise specified. To this composition, other additives may be added. The composition may be used straight or mixed with gasoline. Also, all or part of the methanol may be replaced by ethanol to yield an improved fuel.

[0026] In accordance with the present invention, the following tests were run using a 1973 Lincoln Continental. The series of experiments indicated that a proper mixture of a peroxide with methanol, plus a minor adjustment in the carburetor, eliminates the problems of methanol-gasoline mixtures.

1. Mileage

[0027] A di-tertiary alkyl peroxide (specifically di- tertiary butyl peroxide) and methanol was blended. A mixture of 10% peroxide and 90% methanol was quite efficient but it was found that a 15%-85% mixture was a more optimum ratio. The viscosity of this mixture, being higher than gasoline, necessitated a change in the size of the Lincoln carburetor jets from 61 thousandths to 69 thousandths. With this size jet the peroxide mixture flows freely through the carburetor. This was the only modification made on the Lincoln for all experiments.

[0028] August 12, 1979-Drove the Lincoln 194.4 km (120.8 miles) using 38.991 (10.3 gallons) of regular 89 octane gasoline, giving a mileage of 4.99 km/I (11.73 miles per gallon).

[0029] August 30, 1979-Drove 168.14 km (104.5 miles) using 34,07 I (9 gallons) of a 50-50 blend of methanol 85-peroxide 15 with regular 89 octane gasoline, giving a mileage of 4.93 km/I (11.61 miles per gallon).

[0030] Both tests were run under similar conditions indicating that the mixture had approximately the same mileage as gasoline.

2. Separation of the mixture with water

[0031] September 21, 1979-Added 85.1 g (3 oz.) of water to 3.79 I (1 gallon) of a 50-50 blend of methanol 85, peroxide 15 with 93 octane no lead gasoline. The water separated the mixture into 2 layers. Unexpectedly the peroxide, although more soluble in gasoline, stayed with the methanol and water. The mixture, in its separated form, was then added to the test tank installed in the Lincoln. The Lincoln, taken out on the road, ran perfectly with the separated mixture. The Lincoln also ran perfectly with a mixture of methanol and peroxide with water, but no gasoline.

3. Cold start

[0032] The addition of di-tertiary butyl peroxide to methanol starts a cold motor more easily than does straight methanol. This test is merely indicative and not conclusive since it was done in warm Florida weather.

4. Emissions

[0033] The emissions from the Lincoln were tested September 21, 1979 with the following results:

(Present Government Specifications, at idling speed:

less than 400 P.P.M. Hydrocarbons

less than 2% Carbon Monoxide)

Methanol Peroxide 85-15 mixture:

60 P.P.M. Hydrocarbons

0.1% Carbon Monoxide

Compare: Texaco no lead 87 octane gas:

250 P.P.M. Hydrocarbons

10% Carbon Monoxide

Amoco no lead hi-test 93 octane gas:

180 P.P.M. Hydrocarbons

7% Carbon Monoxide

50/50 mixture of Amoco no lead hi-test 93 octane gas with 85-15 Methanol-Peroxide mixture:

100 P.P.M. Hydrocarbons

2.6% Carbon Monoxide

[0034] Many tests were run with the Lincoln. There was no noticeable difference with gaskets or hoses.

[0035] Although the di-tertiary alkyl peroxides are among the most stable of all the commercially available organic peroxides, the stability of a methanol-peroxide mixture over a long period of time was a concern. One gallon of methanol 85-ditertiary butyl peroxide 15 mixture was blended in a tin can on May 17, 1977, and stored until September 22, 1979. In the test tank on the Lincoln, it gave approximately identical mileage as the same quantity of newly blended mixture. On the same day, September 22, 1979, the same quantity of straight methanol yielded 1/2 the mileage of above old and new mixtures.

[0036] The invention is further illustrated by the following non-limiting examples.

Experiments 18(B) and 18(C)

[0037] Here is demonstrated the fact that by admixture of di-t-butyl peroxide and methanol (ratio 15/85 by-volume), mileage is increased by 61% over that of burning methanol alone: 253 km/I versus 4.08 km/I (5.96 mpg versus 9.60 mpg).

Experiments 16 and 18(H)

[0038] The data in these two experiments would suggest that gasoline diluted 50% with a 45/5 mixture of methanol and DTBP will give about 91% of the mileage produced by gasoline alone.

Experiments 17(B) and 18(C)

[0039] The data suggest the possibility that something of the order of an 80/20 or 75/25 mix of methanol/ DTBP might give better mileage than an 85/15 mixture.

[0040] In addition to the foregoing tests which were performed on an actual automobile, earlier tests were performed on a small motor. The details of these tests appear below:

Motor: Kohler, Model K91, cast iron, air-cooled, 4 cycles, Bore 6.03 cm (2 3/8"), Stroke 5.08 cm (2"), Displacement 145.2 cm³ (8.86 cu. in)., Spark plug gap setting 0.635 mm (.025 in)., breaker point gap 0.508 mm (.020 in.), Horse power rating 4 HP (2.983 kw).

[0041] Engine equipped with hand brake (with crude spring balance gauge). Throttle setting at approximately 4,000 rpm with no load. Attempted to run all mixtures as near 2,500 rpm as possible using hand brake to slow motor.

Experiment #1: Ran 141.75 (5 oz.) Texaco no lead gasoline, reported to be approximately 91 octane. Speed 2,500 rpm, Brake pressure 1.36 kg (3 lbs.) Time 12 1/3 minutes.

Experiment #2: Ran mixture 127.58 g (41/2 oz.) methanol and 14.18 g (1/2 oz.) ditertiary butyl peroxide. Speed 2,700 rpm, Brake 1.36 kg (3 lbs.), Time 14 minutes.

Experiment #3: Ran 127.58 g (4 1/4 oz.) methanol and 21.26 g (3/4 oz.) di-tertiary butyl peroxide. Speed 2,700 rpm, Brake 1.36 kg (3 lbs.), Time 15 1/4-minutes.

Experiment #4: Ran 127.58 g (4 1/2 oz.) methanol and 14.18 g (1/2 oz.) Cumene hydroperoxide. Speed 2,700 rpm, Brake 1.36 kg 3 Jbs., Time 17 3/4 minutes, (Objectionable sweet odor from exhaust)

Experiment #5: Ran 134.66 g (4 3/4 oz.) of #2 mixture and 7.09 g (1/4 oz.) water. Speed 2,000 rpm, Brake 1.36 kg (3Ibs.), Time 18 3/4 minutes. (had to run leaner mixture with throttle adjustment)

Experiment #6: Ran 141.75 g (5 oz.) methanol with throttle adjustment or #5. Speed 2,600 rpm, Brake 1.36 kg (3 lbs.), Time 10 3/4 minutes.

[0042] The following experiments were run at higher speed with throttle open more and brake used to bring speed to approximatley 3,200 rpm.

Experiment #10: Ran 127.58 g (4 1/2 oz.) 190 proof grain alcohol and 14.18 g (1/2 oz.) di-tertiary butyl peroxide. Speed 3,200 rpm, Brake 1.58 kg (3 1/2 lbs.), Time 7 1/2 minutes.

Experiment #12: Ran 141.75 g (5 oz.) Texaco no lead gas. Speed 3,200 rpm, Brake 4,08 kg (9 lbs.), Time 6 minutes. (Blue smoke emission visible).

Experiment #13: Ran 141.75 g (5 oz.) methanol, open throttle to almost maximum to obtain nearly same speed with greater brake pressure. Speed 3,000 rpm, Brake 3.40 kg (7 1/2 lbs.), Time 5 minutes.

[0043] More recent tests run on a General Motor's Chevrolet Citation have indicated that the most dramatic increase in km/I (miles per gallon) for di-t-butyl peroxide (DTBP) and methanol occur with between 1.5-6% by volume DTBP with even negligible amounts being effective. As is shown in the sole figure of the drawing at 1% DTBP and mileage of methanol increased about two miles per gallon. With between 1.5-6% DTBP the increase was between about six to seven miles per gallon. In the drawing the X's represent actual measurements and the O's are an extrapolation of the Lincoln results appearing above multiplied by 2 to approximate Citation mileage results.

[0044] The invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning of the claims are therefore intended to be embraced therein.

Claims

1. A fuel for use in an internal combustion engine, comprising a mixture of methanol and/or ethanol with an alkyl peroxide and, optionally, gasoline, characterized in that the alkyl peroxide is a tertiary alkyl peroxide and that in the case of methanol its content amounts to at least 42.5% by volume.

2. A fuel as set forth in claim 1 wherein said tertiary alkyl peroxide is a ditertiary alkyl peroxide.

3. A fuel as set forth in claim 2 wherein said ditertiary alkyl peroxide is ditertiary butyl peroxide.

4. A fuel as set forth in claim 3 wherein the composition of the fuel comprises substantially only methanol and/or ethanol and ditertiary butyl peroxide in an amount of from 1.5 to 6%.

5. A fuel as set forth in claim 3 wherein the composition of the fuel comprises gasoline mixed with a mixture including 1.5-6% ditertiary butyl peroxide and methanol.

6. A fuel as set forth in any of the claims 1 to 5 also including additives to reduce problems associated with water-methanol mixtures, auto-ignition and knocking.

7. A fuel as set forth in claim 6 wherein the additive includes isopropanol.

8. A method of powering an internal combustion engine comprising burning a fuel in said internal combustion engine, which fuel comprises methanol and/or ethanol or isopropyl alcohol and an alkyl peroxide, characterized in that the fuel comprises as alkyl peroxide an amount of at least 1 % by volume of a tertiary alkyl peroxide.

9. A method as set forth in claim 8 wherein said alcohol is methanol and said tertiary alkyl peroxide is a ditertiary alkyl peroxide.

10. A method as set forth in claim 9 wherein said ditertiary alkyl peroxide is ditertiary butyl peroxide.

Ansprüche

1. Brennstoff für eine Verbrennungsmaschine, wobei der Brennstoff eine Mischung aus Methanol und/oder Ethanol mit einem Alkylperoxid und, gegebenenfalls, Benzin umfaßt, dadurch gekennzeichnet, daß das Alkylperoxid ein tertiäres Alkylperoxid ist und daß im Falle von Methanol dessen Anteil mindestens 42,5% beträgt.

2. Brennstoff nach Anspruch 1, dadurch gekennzeichnet, daß das tertiäre Alkylperoxid ein ditertiäres Alkylperoxid ist.

3. Brennstoff nach Anspruch 2, dadurch gekennzeichnet, daß das ditertiäre Alkylperoxid ditertiär-Butylperoxid ist.

4. Brennstoff nach Anspruch 3, dadurch gekennzeichnet, daß die Brennstoffzusammensetzung im wesentlichen nur Methanol und/oder Ethanol sowie ditertiär-Butylperoxid mit einem Anteil von 1,5 bis 6% umfaßt.

5. Brennstoff nach Anspruch 3, dadurch gekennzeichnet, daß die Brennstoffzusammensetzung Benzin gemischt mit einer 1,5 bis 6% ditertiär-Butylperoxid und Methanol enthaltenden Mischung umfaßt.

6. Brennstoff nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß er ebenfalls Additive enthält, die die mit Wasser-Methanol-Mischungen verbundenen Probleme, S-elbstzündung und Klopfen vermindert.

7. Brennstoff nach Anspruch 6, dadurch gekennzeichnet, daß die Additive Isopropanol umfassen.

8. Verfahren zum Antreiben einer Verbrennungs-maschine, das das Verbrennen eines Brennstoffes in der Verbrennungsmaschine einschließt, wobei der Brennstoff Methanol und/oder Ethanol oder Isopropylalkohol und ein Alkylperoxid umfaßt, dadurch gekennzeichnet, daß der Brennstoff als Alkylperoxid einen Anteil von mindestens 1 Vol.% eines tertiären Alkylperoxids enthält.

9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, daß der Alkohol Methanol ist und das tertiäre Alkylperoxid ein ditertiäres Alkylperoxid ist.

10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, daß das ditertiäre Alkylperoxid ditertiär-Butylperoxid ist.

Revendications

1. Combustible pour l'utilisation dans un moteur à combustion interne, comprenant un mélange de méthanol et/ou d'éthanol avec un peroxyde d'alkyle et le cas échéant de l'essence, caractérisé en ce que le peroxyde d'alkyle est un peroxyde d'alkyle tertiaire et en ce que, dans le cas du méthanol, sa teneur est d'au moins 42,5% en volume.

2. Combustible selon la revendication 1, dans lequel ledit peroxyde d'alkyle tertiaire est un peroxyde de di-tertioalkyle.

3. Combustible selon la revendication 2, dans lequel ledit peroxyde de di-tertioalkyle est le peroxyde de di-tertiobutyle.

4. Combustible selon la revendication 3, dans lequel la composition du combustible ne comprend pratiquement que du méthanol et/ou de l'éthanol et du peroxyde de di-tertiobutyle en quantité de 1,5 à 6%.

5. Combustible selon la revendication 3, dans lequel la composition du combustible comprend de l'essence mélangée avec un mélange contenant 1,5-6% de peroxyde de di-tertiobutyle et du méthanol.

6. Combustible selon l'une quelconque des revendications 1 à 5, contenant également des additifs pour réduire les problèmes associés avec les mélanges eau-méthanol, l'auto-allumage et le cognement.

7. Combustible selon la revendication 6, dans lequel l'additif comprend de l'isopropanol.

8. Procédé pour fournir de l'énergie à un moteur à combustion interne, consistant à brûler un combustible dans ledit moteur à combustion interne, ledit combustible comprenant du méthanol et/ou de l'éthanol ou de l'alcool iso- propylique et un peroxyde d'alkyle, caractérisé en ce que le combustible comprend comme peroxyde d'alkyle une quantité d'au moins 1 % en volume d'un peroxyde d'alkyle tertiaire.

9. Procédé selon la revendication 8, dans lequel ledit alcool est le méthanol et ledit peroxyde d'alkyle tertiaire est un peroxyde de di-tertioalkyle.

10. Procédé selon la revendication 9, dans lequel ledit peroxyde de di-tertioalkyle est le peroxyde de di-tertiobutvle.

Drawing