US3124434A - Astm m - Google Patents

Description

United States Patent 3,124,434 lvETHOl) FOR IMPROVING ANTIKNOCK QUALETY OF GAStBL Robert W. Maione, Rahway, N.J., assignor to Esso Research and Engineering Company, a corporation of Deiaware N0 Drawing. Filed Aug. '26, 1960, Ser. No. 52,041 13 Claims. (Ql. 4469) The instant invention concerns a process for improving the octanenumber of internal combustion engine hydrocarbon fuels. In particular, the present invention relates to a process for improving the antiknock qualities of gasolines and especially gasolines which contain alkyl lead antiknock additives.

For many years, .it has been known that lead alkyl compounds such as 'tetramethyl lead, dimethyldiethyl lead, trimethylpropyl lead and similar alkyl lead additives, and more particularly, tetraethyl lead effect a more or less catalytic action upon the detonation of fuels in which the compounds are employed in minor quantities. Thus, the lead alkyl compounds actto markedly improve the antiknock characteristics of fuels. As .a result of this discovery, compositionslhave been developed and are commercially available consisting of concentrated mixtures of tetraethyl lead or other lead alkyls together with certain other compounds. It is now common practice to add to motor fuels a fluid composition consisting principally of tetraethyl lead and small amounts of ethylene dibromide, ethylene dichloride and other substances in orderto increase the antiknock value of the motor fuel. Most of the gasoline now being sold contains some of this fluid, the amount varying from about 0:5 to 4.5

cc. pergallon of gasoline. Fuels for special purposes, such as aviation gasoline, may contain even more.

The use-of lead alkyl antiknock agents in motorfuels is well known to those skilled in the art. Modern automobileengines have shown a steady increase in compression ratios, and even higher compression ratios are predicted in the future. To meet the 'high octane gasoline quality demanded by these engines, refiners must rely heavily upon effective antiknock additives and catalytic refining operations. Catalytic refining operations, such as fluid catalytic cracking, catalytic reforming, alkyl'ation, catalytic isomerization and-the like, have been particularly util zed to producehigh quality gasolines containing substantial amounts of olefinic and aromatic components. Both olefinic and aromatic components in motor'fuelspossesshigher octane ratingsthanmost paraffinic components, but exhibit a poor response to lead alkyl antiknock additives. The octane increment obtainedby the use of increasing amounts of lead alkyl antiknock additives has diminished as the aromatic and olefinic components of modern gasolines has increased. This is especially true in high quality octane premium fuels of over 100 octane value. Since there are health limitations on the amount of lead compounds that can be utilized in' gasoline, and octane increases in the octane range of over IOO octaneare costly and difficult to obtain, there exists an immediate problem in the industry.

active organic compounds referred to as ketenes wherein the carbonatom of the carbonyl group is directly attached to an adjacent ethylenically bonded carbon atom. These compounds may be represented by the formula:

\C=C=O Rf wherein R and R are organic radicals selected from the group consisting of aromatic, aliphatic and alicyclic radicals and-hydrogen. Where one substituent is hydrogen, the compound is referred to as an aldoketene, while Where both substituents are organic radicals, the compound is referred to as a ketoketene. Suitable treating agents of this invention would include those aliphatic aldo and ketoketenes where -R and'R are selected from the group consisting of alkyl radicals of from 1 to 6 carbon atoms-and hydrogen,-such as dimethyl ketene, diethyl ketene, methyl aldoketene, propyl aldoketene, diphenyl ketene, ketene, dicyclohexyl ketene, methyl cyclohexyl ketene, ethyl phenyl ketene and the like. Especially preferred due to its reactive state, commercial availability, and ease of preparation is ketene. Ketenes may be prepared by well known methods, e.g. from a halogen acyl halides, by theaction of zinc as set forth in DieKetene by H. Staudinger, Stuttgart, 1912 (alsoHelv. Chim. Acta., 1918-1924, same author).

Ketene, the especially preferred treating agent of this invention may be prepared by the pyrolysis of acetone or acetic acid vapor at about 600-750 C. The thermal decomposition of 1 mole acetic acid yields l'mole of ketene and 1 mole of water while the pyrolysis of 1 mole acetone yields 1 mole of ketene and 1 mole of methane. The lattermethod of preparation-is preferred due to the by-product of methane as an inert carrier gas for the ketene.

The liquid hydrocarbon internal combustion fuels benefitted by the treatment with ketene include those liquid petroleum fuels'boiling in the gasoline range, and particularly includes motor and aviation gasolines conventionally used in internal combustion engines. In addition, those hydrocarbon components usedin the blending andmanufacturing of gasolines and fuels may also be beneficially upgraded by the inventive ketene process along with the lubricating and solvent oils added to motor fuels. The use of the-ketene treatment to improve the octane response of solvent oils, lubricating oils, and petroleum distillates, such as virgin and cracked naphthas, solvents, gas oil and the like, subsequently to be utilized as additives or components of the gasoline is advantageous, in that it reduces the necessity for'hydrofining, i.e. treatingwith hydrogen in the presence of a catalyst, theproduct'to achieve a neutralization number reduction and results in other upgraded quality characteristics.

Such gasolines are supplied in a variety of grades, depending upon the particular service or use for which they are intended. The most general classifications applied to such fuels are those of motorgasolines and aviation gasolines. Motor gasolines are defined by ASTM Specification D-439-58T and Federal Specifications VV-G-7'6, dated August 22, 1958, and VV-G-l09, dated April '3, 1950. Such fuels consist of .mixtures of hydrocarbons of various types, including aromatics, olefins, paraflins, isoparaffins, naphthenes, andin some cases diolefins derived from petroleum'by refining processes suchas fractional distillation, thermal cracking, catalytic cracking, hydroforming, alkylation,*isomerization and solvent extraction. Motor gasolinesnormally'boil between about F. and about 450 F. when'tested by ASTMMethodD-d6. Their vapor pressures as determined by ASTM Method D-323 vary, dependingon the season of the year during which they are to be used, from about 7 to about 15 p.s'.i. at

100 F. Their octane numbers, as determined by ASTM Method D-908, may range from about 83 to about 105 or higher. Aviation gasolines are prepared by blending of constituents similar to those found in motor gasolines, but, in general, have somewhat narrower boiling ranges between 100 F. and 330 F., and somewhat more rigid specifications than do motor gasolines. Specifications for aviation gasolines are set forth in US. Military Specification MIL-F-5572B.

Those fuels to which the instant process is particularly applicable are those gasolines having a paraffinic hydrocarbon content of less than 80% and a research octane number above 95.

The novel process of treatment of the fuels can be accomplished by the simple contacting of the fuel and the treating agent in any elfective or suitable conventional manner and then recovering the treated fuel. The mechanism by which the ketene treatment of fuels increases the octane number and beneficially affects the antiknock quality is not entirely understood, but that such ketene treatment is effective can be ascertained by the data presented. Due to the highly reactive character of the treating agens, the treatment is effective at room temperatures and at atmospheric pressure with the contact time of the agent with the fuel not being of a critical nature. A suitable means for carrying out the inventive process would be the treatment of a gasoline or gasoline component in a commercial gas absorption tower-type arrangement such as described in the Chemical Engineers Handbook, edited by John H. Perry, 3rd edition, pp. 668- 711. As an example, the liquid fuel may flow downwardly through the column, while a countercurrent composed of ketene with an inert gas such as methane flows upwardly. The ketene treating agent is consumed in the treating step with a slight increase in temperature of the fuel treated depending upon reactant conditions. The treatment can consist of the contacting of a liquid fuel with a liquid or vaporous ketene depending upon the physical state of the ketene and under the treating conditions employed. The preferred method utilizes ketenes in the vapor state whereby the ketene gas stream is broken up into relatively small vaporous bubbles in order to more effectively contact the liquid fuel. Ketene may be used by itself or in combination with an inert solvent or gas. Any inert carrier which is incapable of reacting at the treatment conditions with the ketene employed in the treatment and the fuel used is suitable. Preferred carriers would include those inactive saturated aliphatic hydrocarbon gaseous compounds, inert gases such as nitrogen, helium or the like, while particularly preferred are those homologues of methane. The upgrading of the fuel may be accomplished by using a clear fuel to which no antiknock additive has been added prior to treatment. This is the preferred method with the subsequent incorporation of the usual quantity of antiknock additives giving unexpected improvement in antiknock effectiveness. In addition, the fuel treated may contain at the time of treat ment an antiknock additive with similar results as above noted after treatment.

Treatment of the fuel with a minor amount of ketene sufiicient to improve the antiknock effectiveness is required, but preferably, the quantity of ketene treatment should be from 0.1 mole/ gal. to 2.0 moles/gal, with from 0.25 mole/ gal. to 1.0 mole/ gal. being especially preferred, for gasoline to which alkyl lead antiknock additives are to be added.

The antiknock agents suitable for incorporation into the ketene treated fuels of this invention either before or after treatment are those organo-metallic antiknock additives containing lead, iron, nickel, and manganese. The preferred antiknock agents are those commercial lead alkyl additives such as tetraethyl and tetramethyl lead. Such lead antiknock agents are normally employed in gasolines in concentrations ranging between 0.1 and 7 cc. per gallon of gasoline. Motor gasolines usually contain up to about 4.0 cc. of the lead compounds per gallon; while aviation gasolines frequently contain higher concentrations. Such lead antiknock agents are always employed in conjunction with halogenated scavenger agents usually boiling within the range between 50 C. and 250 C., such as ethylene romide, ethylene chloride, and the like.

Halogenated scavenger agents are normally employed in gasolines containing lead antilcnock agents in concentrations ranging from about 0.5 to about 3.0 theories, one theory being the amount of scavenger stoichiometrically equivalent to the lead in the gasoline. One theory of ethylene dichloride, for example, is the amount of the scavenger required to provide suificient chlorine atoms to form lead chloride. In gasolines containing tetraethyl lead and tetramethyl lead and similar alkyl lead antiknock agents, it is generally preferred to use from about 0.8 to about 1.5 theories of ethylene dibromide if a single scavenger agent is to be employed, or from about 0.8 to 1.5 theories of ethylene dichloride and from about 0.3 to about 0.8 theories of ethylene dibromide if a mixed scavenger agent is used.

After ketene treatment, the fuels so treated may contain other additive materials conventionally employed in gasolines. Such other additives include upper cylinder lubricants and solvent oils, for example, solvent oils consisting of hydrocarbon mixtures having a Saybolt viscosity not exceeding about 450 seconds at 100 F., a 50% distillation point above about 350 F. at 10 mm. of mercury pressure, and an API gravity between about 18 and about 28. Corrosion inhibitors such as alkyl acid phosphates, amines, amine phosphates, dimerized linoleic acid, and other carboxylic acids may also be present. Other additives useful in such gasolines include gum in- =hibitors such as N,N-di-secondary-butyl-P phenylene diamine; 2,4-dimethyl-6-tertiary butyl phenol and 2,6-ditertiary butyl-4-methyl phenol. Also useful are anti-icing agents such as isopropanol, hexylene glycol, Carbitol and dimethyl formamide. Such gasolines also conventionally contain dyes such as 1,4-diisopropyl-amino anthra quinone and p-dimethyl-amino-az0benzene, and dye stabi lizers such as ethylene diamine. Auxiliary scavengers other than those mentioned such as tricresyl phosphate, isooctyl diphenyl phosphate, methyl diphenyl phosphate, etc., can also be used in conjunction with the antiknock additives described.

The exact nature and objects of the invention can best be understood by reference to the following examples:

EXAMPLE 1 Laboratory octane ratings of the Research Octane Number and the Motor Octane Number were obtained with fuel compositions by using the Direct Match Method. The Direct Match Method of determining octane rating numbers is based upon the determination of the octane rating of the test sample side by side with a calibrated prototype sample of similar antiknock quality and composition in the same engine and at the same compression ratio while feeding the samples alternately through separate carburetor bowls in parallel. The differences between the calibration octane values and the determined octane rating for the prototype rfuel are added algebraically to the octane rating of the test sample to obtain corrected octane ratings for the said test sample. The apparatus and procedure used in this Direct Match Method is the same apparatus and general procedure to determine octane ratings by ASTM Method D908 and ASTM Method D-357. The calculations and reporting are done by subtracting the prototype rating from its calibration value and adding this AO.N. algebraically to the rating of the test sample to obtain a corrected rating for the test sample. The corrected octane rating is then reported.

The Research Octane Number (RON) of both base gasolines was determined by the Standard ASTM Research Method Test Procedure D-908-51, which is de- 'D357,- which is set forth in the 1953 edition of ASTM Manual of Engine Test Methods forRating Fuels.

The base gasolines-used had the following characteristics:

' Base Gasoline ASTM Distillation A B C Initial Boiling Point, F 93 89 96 10% Boiling Point, F 135 125 137 50% Boiling Point, T... 225 235 238 90% Boiling Point, W. 286 302 271 Final Boiling Point, "F 356 371 306 Gravity, API 63.1 54. 5 45. Reid Vapor Pressure, p 8.0 13. 8.9 Research Octane Number 103. 102. 7 110. 6 Motor Octane Number 94.0 92.0 97.0 Aromatics Percentage 20.0 46. 9 64. 3 Olefins Percentage 10.1 7. 7 0.7 Saturates Percentage 69.9 45. 4 35. 0

The treating agent, ketene, was prepared by the use of a ketene generator as described in the textbook Feiser and Feiser, 3rd edition, pages 186-187, which method produces ketene and methane by the pyrolytic decomposition of acetone vapors on an electrically heated wire. The decomposed vapors were passed through a Dry Ice trap to remove unconverted acetone, and the vaporous ketene and methane by-product passed directly into the base fuel through a sparger. The sparger was a glass delivery tube whose lower end was immersed in the 'base fuel, and which lower end had a spun glass filter, whose function was to disperse the ketene gas stream into small bubbles for more eifective contact with the liquid fuel. The rate and amount of ketene generated was checked by treating an aqueous alkaline solution under the same conditions and determining the change in hydroxyl ion concentration by titration. The ketene concentration delivered to each fuel sample was determined from the treatment rate and time of treatment.

The unexpected and improved quality of ketene treated fuels can be ascertained by reference to the experimental data of Table I.

Table 1 EFFECT OF KETENE TREATMENT ON GASOLINE Grams of Fuel TEL ketene RON ARON MON AMON ccJgal. per gal.

fuel

l Tetraethyl lead with 1.0 theory of ethylene dichloride and 0.5 theory of ethylene dibromide.

2 The TEL mixture was added after the ketene treatment of the clear unleaded fuel.

The above data clearly demonstrate the beneficial effect of ketene treating gasoline fuels. The unexpected results of the inventive process are effective even with very high octane fuels such as fuel C in the above table. The economic significance of such process treatment is thereby established as one of importance. That the process in some manner is beneficial to the fuel itself is demonstrated by the results where the process treatment in gasoline containing a lead antiknock additive is very effective in improving the antiknock quality of a wide variety of fuels, e.g. A, B, and C. In addition, the ketene treatment of clear unleaded gasoline, although not demonstrably effective in-improving the octane quality while unleaded, greatly improved in quality upon the subsequent addition of the lead antiknock additive.

EXAMPLE 2 The beneficial effects of the treatment of fuels with ltetenes has been discovered to bein relative proportion to the amount of time of ketene treatment of the base fuel. This is shown by the following data of Table II, which are the mean results of duplicate measurement of a gasoline fuel containing 3 cc. per gallon of tetraethyl lead. The base fuel used is that gasoline designated as fuel A.

T able II EFFECT OF KETENE CONCENTRATION Treating Time Weight of in Minutes Ketene per RON ARON MON AMON gal. of Fuel In summary, the applicant has discovered a novel process for improving fuel quality, which process comprises contacting the fuel with ketenes to improve the octane quality.

What is claimed is:

1. A process for the improvement of motor fuels, which process comprises:

treating a gasoline with a minor amount sufficient to improve the antiknock response of said fuel of an organic ketene having the formula:

wherein R and R are selected from the group con sisting of hydrogen and aliphatic, unsubstituted alicyclic and aromatic radicals whereby the treated fuel exhibits an enhanced responsiveness to lead antiknock additives.

2. A process as defined in claim 1 wherein said fuel prior to treatment contains a minor amount sufiicient to reduce [knock of a lead antiknock agent whereby said treatment improves the octane quality of said leaded fuel.

3. A process as defined in claim 1 wherein said fuel is treated with from 0.1 to 2.0 moles of the organic ketene per gallon of fuel.

4. A process as defined in claim 1 wherein said fuel has a paraffinic content of less than by volume and a Research Octane Number of above 95.

5. A process as defined in claim 1 wherein said organic ketene is ketene.

6. A fuel composition as produced by the process of claim 1.

7. A fuel composition as produced by the process of claim 2.

8. A process as defined in claim 1 which comprises additionally the subsequent incorporating of a minor amount of a lead alkyl antiknock additive into the treated fuel, whereby enhanced antiknook qualities are obtained.

9. A fuel composition as produced by the process of claim 8.

10. A process for improving the antiknock quality of a gasoline, which process comprises the contacting of the unleaded gasoline with from 0.1 mole to 2.0 moles of ketene per gallon of gasoline whereby the contacted fuel exhibits an enhanced responsiveness to lead antiknock agents.

11. A process as defined in claim 10 wherein said gasoline prior to contacting contains a minor amount of an alkyl lead additive compound sufiicient to improve the antiknock quality of the fuel.

12. A process as defined in claim 10 which comprises additionally the subsequent incorporating of a minor amount of a lead alkyl antiknock additive into the treated fuel, whereby enhanced antiknock qualities are obtained.

13. A process for improving the antiknock quality of clear unleaded gasoline, which process comprises the contacting of the liquid gasoline with from 0.25 mole to 1.0 mole per gallon of ketene vapor, the recovering of said gasoline, and the subsequent adding to the recovered gasoline from 1.0 to 7.0 cc. per gallon of tetraethyl lead, whereby the antiknock qualities of the gasoline are enhanced beyond that normally expected.

References Cited in the file of this patent UNITED STATES PATENTS Conquest Nov. 23, Schneider et a1 Oct. 17, Lipkin Aug. 13, Schneider et a1 Dec. 24, Miller Apr. 6, Fields et al Jan. 19,

FOREIGN PATENTS Great Britain Feb. 27,

Claims (2)

1. A PROCESS FOR THE IMPROVEMENT OF MOTOR FUELS, WHICH PROCESS COMPRISES: TREATING A GASOLINE WITH A MINOR AMOUNT SUFFICIENT TO IMPROVE THE ANTIKNOCK RESPONSE OF SAID FUEL OF AN ORGANIC KETENE HAVING THE FORMULA:

2. A PROCESS AS DEFINED IN CLAIM 1 WHEREIN SAID FUEL PRIOR TO TREATMENT CONTAINS A MINOR AMOUNT SUFFICIENT TO REDUCED KNOCK OF A LEAD ANTIKNOCK AGENT WHEREBY SAID TREATMENT IMPROVES THE OCTANE QUALITY OF SAID LEADED FUEL.