US2668522A

US2668522A - Motor gasoline additive

Info

Publication number: US2668522A
Application number: US258992A
Authority: US
Inventors: John E Hickok; John A Ryan
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1951-11-29
Filing date: 1951-11-29
Publication date: 1954-02-09
Anticipated expiration: 1971-02-09

Description

lated based on customer reaction surveys, care- 7,

fully controlled road tests, and laboratory cold- 7 4- 1 case dilution. Howeverfin appreciating the scope of the present invention, it is important to note that this invention is only of application to gasroom engine performance tests. :1 These tests;

show that carburetor icing depends primarily upon atmospheric temperature and humidity; The tests show thatstalling diificonditions. H culties due to ice formation in the carburetor are not encountered below about 30F, nor above about 60 F. when employing" fuelshaving'conventional volatility characteristics. Similarly,

these tests demonstrate that stalling is only encountered when the humidity is in excess of about'65'%. i

Another factor having a bearing onthe formation of ice in' the carburetor, is the volatility of the fuel-employed- To determine this effect, laboratory cold room tests were conducted to evaluate the stalling characteristics during warm-up of a number of fuels varying in volatility. In these tests a 1947 Chrysler car was installed in a room equipped with temperature and humidity controls. While the temperature and humidity were maintained at particular levels, thestalling characteristics of the car were determined during the warm-up period. The procedure'employed was to start the car an then immediately to raise the engine speed to 1500 R. P. M. This speed was maintained for 30 seconds, after which the engine was allowed to idle for seconds. If the engine stalled before 15 seconds had expired, the car was again started and raised to a speed of 1500 R. P. M. for seconds', while if stalling did not occur, the speed was immediately increased to 1500 R. P. M. after the 15 second idling time. The alternate cycles of 30 seconds at 1500 R. P. M. followed by 15 secends at idling were repeated until the engine was completely warmed up. The number of stalls encountered during this procedure, and up to the time of complete engine warm-up were then recorded. Tests were conducted at 40 F. and at a relative humidity of 100% employing three fuels of varying volatilities. The most volatile fuel was a premium grade of commercial gasoline having a 10% .ASTM distillation. point of 110 F.,:a point of 190 F., and a point ofv 294 F; Itwas found thatthis fuel resulted in about 14; or 15 stalls during warm-up. A medium volatility fuel was also tested, consisting of a regular ,gradecommercial gasoline having ASTM distillation characteristics such that 10% distilled at 121 R, 50% distilled at 220 F., and distilled at 342 F. The number of stalls encountered with this fuel were 11. Finally a low volatility gasoline was subjected to the same test procedure. The "gasoline had ASTM distillation 10, 50, and 90 points, at 126 F., 270 F. and 387 F. It was found that 5 stalls were encountered with this fuel;

" As indicated by these data, carburetor icing is related to the volatility of the fuel employed. Thus, the least volatile fuel tested'above, having a 50% distillation point of 270, only resulted in 5 stalls, while the highest volatility fuel, having a 50% distillation point of 190 F., resulted in 15 stalls. Extrapolating these data as to the volatility of the fuel, it appears that a fuel having a volatility such that the ASTM 50% distillation point is 310 F., or higher would not be subject to stalling difficulties during warm-up. be appreciated, however, that a fuel having It must ASTM distillation characteristics of this nature;

would not be desirable as regards warm-up time, cold engine acceleration, economy and crank to gasoline.

oline fuels having an ASTM 50% distillation point below about 310 F. At the same time, as will be brought out, it is possible to correlate the quantity of additives required to overcome icing problems with the volatility of the fuel to be improved. In other words, smaller proportions of additives may be employed with fuels of relatively low volatility, while higher proportions of additives may be required with fuels of higher volatility.

As will be brought out by the data which follow, it will be shown that stalling difliculties may be overcome by employing critical percentages of dimethyl carbinol together :with diisopropyl ether anda conventional solvent oil. Each of these additives contributes to the. solution of the. icing problem. The solvent oil, being a. low volatility heavy oil, serves to maintain an oil film over the carburetor parts so as to minimize the adherence of moisture and ice to the carburetor. The dimethyl carbinol is sufficiently volatile and water soluble to vaporize in the carburetor and to dissolve in moisture. present so as to depress the freezing point of the moisture. Together then, the dimethyl carbinol sharply lowers the freezing point of moisture in the carburetor while the solvent oil decreases the adherence of moisture and ice to the carburetor. The ether reduces still further the accumulation of ice, apparently through synergistic association with dimethyl carbinol since the ether in the absence of dimethyl carbinol has no effect on ice accumulation. This synergism occurs in the presence or in the absence of solvent oil.

It is a .particular feature that by jointly using solvent oil, dimethyl carbinol and the ether, each component contributing a different function in preventing carburetor icing problems, it is possible to achieve a very high degree of anti-icing with only about 0.5% of solvent oil, not more than 2.5% of dimethyl carbinol, and from 0.05 to 0.2% of the ether.

.With regard to the solvent oil to be used, this consists essentially of a liquid hydrocarbon mixture having a kauri-butanol solvent power above about 20, having a 50% distillation point above 350 F., at 10 mm. mercury pressure, having a Saybolt viscosity at F., not above 450 seconds, and having an API gravity of about 18 to 28. It is to be understood, therefore, that in referring to a solvent oil throughout this specification, reference is made to an additive of this nature, as defined above.

The dimethyl carbinol, or isopropanol, to be employed must be of 98% purity, or greater, although it is preferred that 98% .pure dimethyl carbinol be employed. This chemical is ordinarily produced as crude dimethyl carbinol having a purity of 65%. The 35% of impurities cons st chiefly of water together with small quanties of di-isopropyl ether, higher carbinols and ketones. Use of the crude product of this nature can not be tolerated, in part since a phase separation would occur on adding the crude product The consequent phase operation would result in an aqueous phase and a gasoline phase containing about 98% pure dimethyl carbinol. It is presently contemplated that, if decontaining dimethyl carbinol of 98% purity. It

is preferred, however, to purify- .the dimethyl carbinolin the conventional manner. to, obtain sub,-

stantially pure dimethyl carbinol. having. less.

than 2% of, water, The. purified, dimethyl carbinol of greater than 98% purity. may. then be blended directly into the gasoline.

As. an aid in understandingtheprinciples of this mixture, itis of interest to note that homo-.

logues of dimethyl carbinol. cannot satisfactorily.

be employed. In the case of, higher molecular Weighthomologues, it has been found; that normal propyl carbinol, .iso-propyl carbinol and ethyl methyl carbinol, together withgall, other higher homologues are not sufliciently water soluble to be efiective for suppressing theformationof care buretor ice. In the case ofv dimethyl carbinol,

apparently sufiicient quantities of .thiscompound.

dissolve in any water condensed in the, carburetorso as to sufiiciently lower the .freezingpoint of 7 this water to prevent ice formation. However, in the case of the higher carbinols, solubility is not sufficient in the water to'permit; this efiect. A further considerationin this connection isthat it is desirable to employ a compound having as low a molecular weight as possible, to depress the freezing point of water to the, maximum extent according to Raoults law. However, it has also been found impossible to use. carbinols of lower molecular weight than dimethyl, carbinol. Thus in the case of carbinol, or methanol, the volatility is such that the compound would notcondense on the throttle plate of the carburetor, and apparently for this reason-has little eflect in suppressing icing. Asa further consideration, gasor' line compositions containing carbinol are extremely water sensitive so that the unavoidable contact of gasoline with water during marketing, or in a car, would result in the loss of most, or,

all or the compound. Methyl carbinol, or ethanol, is similarly objectionable particularly on.

the basis of Water sensitivity. Thus on contact of any gasoline composition containingthese compounds with, for'example, the water which may be present in storage tanks; most' of the compounds would be leached out by the; water. To clearly show this made to data obtained by contacting gasoline compositions containing, respectively, 2% ofcarbinol, methyl carbinol, and dimethyl carbinol,

with two volume percent of ,Water. Itjwas found a that 81% of the carbinol was water, while 65% moved, while only was lost.

The compositions embraced within this invention may be more fully understoodby reference to the following examples, which show the effect of solvent oil alone; dimethyl carbinol alone; solvent oil and dimethyl carbinol; and solvent oil, dimethyl carbinol synergistic association.

removed by the of the methyl carbinol was reof the dimethyl carbinol Example I A commercial automotive gasoline was subjected to the cold startingtests formerly described. This gasoline had the following inspections:

eifect, reference may be and diisopropyl ether in 10% D+L Fi 134- 50% D-l-L F 209 n+1. ?r 3.05 Reid'vapor pressure 91.2 Gravity i ,API 6. .1

Itwas foundthatthis gasoline-stock result d. in nstaus during the tes'tprocedure;or dnringthe warm-up time of the engine at40F.', and%" relative humidity. 0:5 avolnmmpercent of solvent oil was thenadded to the gasoline...v This, solven oil-hadthe. followin characteristics:

K'auri'ebutanol; value; 50 distillatiompoint; i413: Say-bolt-..viscosityrat- 1005 FE 75.3 A. Ilgravity; 262.6

1 At 10=1um. Hairless...

It was determined, that s the icingicharacteristics ofithe. carburetor were improved since warm-up- I was accomplished withgonly-8or:9stalls;

Since the sol'ventoil' is 'sumciently non-volatile to form a liquidgfilm; on: the. carburetor-par i appears that-this film is effective 'to' decreasethe condensation or adherence-o1 water and ice in the carburetor. Howeven this effect of solvent oil is apparently not suitable to eliminate icing problems completely. Thus when the percentage of solvent oil in the gasoline of this example was doubled, no appreciable zimprovement;in enginezoperation was obtained. So whilethe-liquid-film forming eifectof solvent oilmayberelied-ron to' decrease icing, problems, resort-must;- be hadEtO- other agents to coact with. thesolvent; oil; to completely eliminate icing difiiculties;-

Data of the nature indicatedin.this-example therefore shows that about;0.5%. 0f;;1s olvent;oi1, improve 7 unsatisfactory carburetor, icing; and:

is suficient to materially. engine operation due to that use of greater proportions. provideslittle if any incremental improvement. It is preferred that the. quantity .of solvent. oil; should .not-exceed about 0;.5

volume-since changes distillation or, volatility characteristics of gasoline when presentinan-y substantial portions, and-since. it. also; adversely. changes-the. octane number of therfuel. gum test inspections.

Example 2 To the base gasoline employedriniExamplerl, 1% of 99% dimethyl carbinol=wasladdedx It :was found that the number" during warm-up with.this: fuelztcomposition hadbeen reduced from a control:value:of about=1l to about 6. These data, therefore; indicate that 1 of dimethyl carbinol is sufficient-to eifect an appreciable improvement in the carburetor icing characteristics of a'base gasoline.

Example. 3:

In. understanding this coaction,.it..is .,helpful to realize that at least. a portionofthedimethyl carbinol will be maintained solution imthe film of solvent: oil. The solvent oilthus has the it .materially and. the. copper. dish.

of t stalls: encountered point where it is needed. I

' Example 4 To determine the efiect of employing small quantities of solvent oil and dimethyl carbinol in gasoline, experiments were conducted with a gasoline containing 0.5 volume percent of solvent oil and 0, 1, and 2% of dimethyl carbinol. The base fuel employed, consisting of a premium brand commercial gasoline containing 0.5% solvent oil and 1.38 cc. per gallon of lead tetraethyl which will be identified as Fuel Base A, had the characteristics indicated in the following Table 2. Also indicated in the table are the characteristics of this fuel base plus 1 and 2 volume percent of 99% pure dimethyl carbinol.

TABLE 2 Fuel A Containing 0.5% Solvent Oil Vol. Percent (99% Dimethyl Carbinol) 1 2 ASTM Distillation, I. B. P., F 84 86 87 F. for 10% D+L 110 106 105 F. for 50% D-i-L 190 190 187 F. for 90% D+L 294 293 292 Percent D-l-L (a) 158 F. 34. 5 35.0 37. 5 Reid Vapor Pressure, p. s. 13.2 12. 8 12.3 Gravity, API 66.3 66.0 85. 7 General Motors Gum, mgJlOD ml 0.8 0.8 2. 2 Copper Dish Gum, rug/100 ml 276 251 238 ASTM Breakdown, Minutes. 454 300 338 Motor Octane Numbcr.- 82. 2 82.0 82. 2 Research Octane Numben 01. 4 91. 0 91. 7 Lead Content, ccjgal 1 38 1. 37 1.35

It will be noted from this table that addition of 1 and 2% of dimethyl carbinol to the base fuel stock containing the solvent oil does not adversely affect the inspections of the fuel. It is significant that even at 2% concentration, suflicient dimethyl carbinol was not present to affect the octane rating of the fuel outside of the experimental error involved in octane determinations.

.Laboratory cold room tests were then conducted according tothe afore-described procedure to determine the carburetor icing characteristics of a car containing the fuel compositions of Table 2. Results of these tests are given in Table 3. By way of explanation, it may be noted that the temperature and humidity conditions of the test were chosen as being the most severe which could be encountered as regards stalling tendency. Thus, by the nature of tests formerly indicated involving consumer reaction, laboratory tests, and road tests, it was determined that engine stalling occurs most frequently at a temperature of about 40 F., when the humidity is relatively high.

TABLE 3 Laboratory tests-1947 Chrysler :Referring to Table 3, it will be noted that the base fuel identified as Fuel A and containing 0.5% of solvent oil Was subject to an average of about 14.5 stalls during the warm-up time, at a humidity of 100%. The frequency of stalls was somewhat less at the lower humidity levels of and 80%; When 1% of dimethyl carbinol was added to Fuel A, it was found that no stalling occurred at relative humidities below about and thateven at relative humidity, only about 2 stalls occurred during warm-up. Finally, it will be noted that addition of 2% and 2.5% of dimethyl carbinol effected a greater improvement in stalling causing the frequency of stalls to be respectively about 1 and about 0.5 during warm-up; and further limiting the humidities at which stalling could occur to relative humidities of about 99%, or greater. The data of Table 3, therefore, fully demonstrates the advantageous characteristics of the compositions of this invention. That is, the data show that a gasoline fuel containing 0.5 volume percent of solvent oil, and from about 1.0% to 2.5% of dimethyl carbinol is substantially free of stalling tendencies.

The indicated compositions are completely free of adverse carburetor icing below relative humidities of 95%, and at 2% concentrations of dimethyl carbinol do not permit stalling at relative humidities below 99%. In addition, these fuel compositions under the most adverse conditions would not be subject to stalling except in an extremely narrow temperature region. Thus with the 1% dimethyl carbinol blend, carburetor icing would ordinarily not occur except at relative humidities above 95%, and then only when ambient temperatures are in the range of about 38 F. to 42 F. It should further be noted in connection with the data of Table 3, that Fuel A employed in this table is a relatively high volatility fuel having a 50% distillation point of F. This volatility is such that the commercial gasoline having this volatility is ordinarily described as approaching the volatility I characteristics of aviation fuels. Consequently, in extrapolating the data of Table 3, to regular brand gasolines having lower volatility it is apparent that addition of 0.5% solvent oil and from 1 to 2% of dimethyl carbinol is effective in substantially eliminating carburetor icing difficulties.

From the foregoing it is apparent that improved fuel compositions are secured when utilizing an alcohol, particularly dimethyl carbinol in conjunction with a solvent oil. It has now been discovered that a" further improvement is secured provided a relatively small amount of diisopropyl ether be utilized in conjunction with the hydrocarbon-alcohol mixture. In accordance with the present invention, it is preferred to use from 0.5 to 2.5% by volume (based upon the motor fuel) of a low molecular weight alcohol, particularly dimethyl carbinol in a motor gasoline and to use in conjunction with the low molecular weight alcohol from .05 to 0.2% by volume (based upon the motor fuel) of an ether. particularly diisopropyl ether.

The'present invention may be more fully appreciated by the following example illustrating the same.

Example 5 In a series of carburetor icing tests, blends containing dimethyl carbinol and diisopropyl ether in a motor fuel of the type of premium igradezmotor gasoline and containing abQut'i0'5% selvent were used. 'sumgasonnemcrmauy contains ethyl fluid" corresponding to'b'etween 1 and 3 cc. dftetraethyl 'leadpfl gallon of gasi olineiand normally hasfiatil-east 80 octane num- --:ber. Agasoline having'caniinit-ial boilinggpoint 60% distilled at 212 F., and about 90% distilled at 302 F. by ASTM Method 13-86, was mixed with various percentages of dimethyl carbinol and diisopropyl ether and the icing characteristics of the fuels were determined. The fuel was carbureted by air saturated with water at about 40 F., employing an air-fuel ratio of about 12/1 by weight. The minutes of elapsed time prior to the first indication of ice formation on the carburetor throttle plate are shown in Table 4.

TABLE 4 Carburetor icing tests Volume Percent Time to Initial Ice Formation, Dimethyl Diisopropyl Mins.

Garbinol Ether Example 6 In another series of tests, a mixture containing about 92% dimethyl carbinol, 6% diisopropyl ether and 2% water by volume was added in various proportions to a gasoline similar to that employed in Example 5 and containing about 0.5% of solvent oil. The icing characteristics of the resulting blends, as determined in the carburetor icing apparatus, are shown in Table 5.

TABLE 5 Carburetor icing tests Volume Percent:

Dimethyl Oar- Time to Initial binol, Diisopro- Ice Formation, pyl Ether Mix- Minutes ture None 0.7 0.5 0.6 1.0 0.8 1.5 5.1 2.0 10+ The data show that decidedly superior results are obtained by employing dimethyl carbinol, diisopropyl ether and solvent oil in particular proportions and in particular concentrations.

It is apparent that the fuel compositions falling within the scope of this invention may include any of the commonly used gasoline additives, such as lead alkyl anti-detonants, lead bpesfsae scavenging .agents,,1dyes, lgum'finh'ibitors, oxidation inhibitors, .etc. LItlisparticularly-contemplated that i metal. deactivators andl-rlust preventives may be included in th'eiuel. N;N.' -disa'li- "cylal-fl; 2-diamin'o propane,fiand"N;N'disalicylal- '1,2-diamino ethane are exampiesbrsuitabiemeta1. deactivators. sorbitan monoleate, pentae'rythritolLl-inonoleateiand phosphates, nitrates, and nitrites suchas "the amine phosphates, nitrates, andnitrites are examples of suitable .rus t :preventiveswhich may be used. It is apparent that this invention-"is oi"application't'o -any gasoline fuel ba'se having a volatility isuch thatzthez'% distillaticnipoint .falls..below. about 310E2E1l ifli'he gasolines thus include automotive type gasolines, marine type gasolines, and aviation gasolines.

What is claimed is:

1. A composition consisting of a mixture of hydrocarbons boiling in the gasoline boiling range and containing from about 1.0 to 2.5% by volume of dimethyl carbinol and from about .05 to 0.2% by volume of diisopropyl ether.

2. Composition as defined by claim 1 wherein said composition contains about 0.5% by volume of a solvent oil.

3. A composition consisting essentially of a mixture of hydrocarbons boiling in the gasoline boiling range and containing about 0.5 volume percent of solvent oil, from about 1.0 to 2.5% by volume of dimethyl carbinol and from about .05 to 0.2% by volume of diisopropyl ether, said solvent oil consisting of a liquid hydrocarbon mixture having a kauri-butanol solvent power above about 2-0, a distillation point above about 50 F. at 10 mm. mercury pressure, a Saybolt viscosity at 100 F., not above 450 seconds, and an API gravity of about 18 to 28.

4. The composition of claim 3 in which the concentration of the said dimethyl carbinol is 2.0%.

5. The composition of claim 3 in which the said dimethyl carbinol consists of at least 98% pure dimethyl carbinol.

6. A gasoline composition including 0.5% by volume of solvent oil and 1.9% by volume of 98% pure dimethyl carbinol and 0.1% by volume of diisopropyl ether.

7. The composition defined by claim 6 in which the mid-boiling point of the said mixture of hydrocarbons boiling in the gasoline boiling range is below about 310 F.

8. The composition defined by claim 6 in which the said mixture of hydrocarbons boiling in the gasoline boiling range has a mid-boiling point of about 190 F.

9. The method of operating an internal combustion engine in moist, cool temperature conditions which comprises burning a. gasoline fuel in the said engine containing about 0.5% of solvent oil, 1.9% of dimethyl carbinol of at least 98% purity and about 0.1% of diisopropyl ether, said solvent oil consisting of a liquid hydrocarbon mixture having a kauri-butanol solvent power above about 20, a 50% distillation point above 350 F., at 10 mm. mercury pressure, a Saybolt viscosity at 100 F not above 450 seconds, and an API gravity of about 18 to 28.

10. The method of improving the combustion of a gasoline fuel at ambient temperatures between 30 and F., and employing air having relative humidities greater than about which comprises burning said gasoline fuel and said air in the pressure of about 0.5 volume percent of solvent oil and 1.9% of dimethyl carbinol based on the quantity of gasoline, and--about 0.1% 01' diisopropyi ether said solvent oil consisting of a, liquid hydrocarbon mixture having about 18 to 28".

JOHN E. I-IICKOK.

JOHN A. RYAN.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Bue June 30, 1936 Number 2.046.243

Number Number 12 Name Date Hooton Aug. 29, 1941 Neudeck Dec. 25, 1951 FOREIGN PATENTS Country Date Great Britain 1938

Claims

9. THE METHOD OF OPERATING AN INTERNAL COMBUSTION ENGINE IN MOIST, COOL TEMPERATURE CONDITIONS WHICH COMPRISES BURNING A GASOLINE FUEL IN THE SAID ENGINE CONTAINING ABOUT 0.5% OF SOLVENT OIL, 1.9% OF DIMETHYL CARBINOL OF AT LEAST 98% PURITY AND ABOUT 0.1% OF DIISOPROPYL ETHER, SAID SOLVENT OIL CONSISTING OF A LIQUID HYDROCARBON MIXTURE HAVING A KAURI-BUTANOL SOLVENT POWER ABOVE ABOUT 20. A 50% DISTILLATION POINT ABOVE 350* F., AT 10 MM. MERCURY PRESSURE, A SAYBOLT VISCOSITY AT 100* F., NOT ABOVE 450 SECONDS, AND AN API GRAVITY OF ABOUT 18 TO 28*.