US2927012A - Fuel oil composition - Google Patents

Description

,U ts lsrata Pa ai FUEL OIL COMPOSITION Robert J. Hartle, Gibsonla, Pa., assignor to Gulf Research 8: Development Company, Pittsburgh, Pa., a corporation of-Delaware No Drawing. Application December 18, 1957 Serial No. 703,498

'1 Claims. 01. 44-57 This'invention relates to hydrocarbon fuel oils having improved ignition characterisics. More particularly, the invention relates to hydrocarbon fuel oils containing addition agents that are adapted to enhance the ignition and combustion characteristics of such oils.

Hydrocarbon distillates and residual-containing oils having distillation characteristics, viscosities, carbon residues and other properties rendering them otherwise suitable for use as fuels for compression ignition or diesel engines, or other atomizing or vaporizing type burners, frequently have ignition characteristics that render them unsuitable or only poorly suitable for such use. Fuels that have poor ignition characteristics, that is, relatively high spontaneous ignition temperatures, will'exhibit an unduly large ignition lag between the time the fuel is injected in the'combustion zone'and the time when the fuel ignites. In diesel engines, for example, a large ignition lagwill result in the combustion of the fuel-and the development of pressure over the improper portion of the crank angle period and piston stroke, and this will be accompanied by knocking, rough engine operation, in-

complete combustion in the combustion zone, power loss, etc. The ignition quality of diesel fuels is normally expressed in terms of cetane numbers. The cetanenumber of a given fuel represents the percent proportion of cetane, a fast-burning C paraifinic constituent, in a methylnaphthalene, a slow burning aromatic material, that will match the performance of the given fuel at the same compression ratio in a standard test engine.

The present invention relates to hydrocarbon fuel' oil compositions that possess enhanced ignition quality and other performance characteristics, and which are-there"- fore better adapted for use. in diesel engines and other atomizingor vaporizing type burners. l have found that such improved hydrocarbonfuel oil compositions-can .be

obtained by incorporating in the oils a small amount of an aldehyde or ketone cyanohydrin nitrate derived from an aldehyde or ketone having as one substituent a hydrocarbon radical that contains 1 to 18 carbon atoms, and as the other a radical of the same class or hydrogen, whether or not the substituents are separate radicals or-ditferent.

portions of the same radical. The radicals referred to can be saturated or unsaturated, straight or branched chain, cycloaliphatic, aromatic, or heterocyclic. Examples of decadienyl, cycloalkyl radicals, such as cyclohexyl and cyclopentyl,.-aryl radicals. .such as phenyl and, .naphthyl,

alkaryl radicals such as cresyl and tolyl, aralkyl radicals such as benzyl, and heterocyclic radicals such as furyl.

The radicals cankbe unsubstituted as indicated, or they can be substituted with substituents such as halogen, alkoxy,

nitro or the like, that do not adversely affect the oilsolubility or combustion characteristics of the oil or the stability of -the resulting cyanohydrin nitrate. The cyano- 7 Patented Mar. 1, 1960 hydrin nitrates derived from alkyl substituted aldehydes or ketones, particularly those whose alkyl substituents contain 1. to 12 carbon atoms, are especially valuable, acetone cyanohydrin nitrate and 2-ethylhexaldehyde cyanohydrin nitrate being preferred members of the class. The exact mechanism by which the cyanohydrin nitrates disclosed herein function toimprove the ignition characteristics of the fuel oils has not been definitely established. It rnight appear that these materials function by rapid decomposition at a lower temperature than. the spontaneous ignition temperature of the fuel oil, the heat evolved during such rapid decomposition functioning to ignite the fuel oil at a time prior to that at which the spontaneous ignition temperature would be reached. The decomposition of the cyanohydrin nitrates may also promote decomposition of the fuel oil components into materials that are more easily oxidizable and which. therefore possess relatively low spontaneous ignition temperatures. a The cyanohydrin nitrates disclosed herein are employed in hydrocarbon fuel oils ina proportion such as to improve the ignition quality of the oil. Such proportion will 'vary somewhat according to the nature of the fuel oil and on a weight basis according to the nature of the individual cyanohydrin nitrate. Normally, a noticeable improvement in the ignition quality of a fuel oil will be obtained by incorporating therein as little as 0.05 weight percent of the cyanohydrin nitrates disclosed herein, and the use of 0.1 weight percent to 2.0 weight percent will result in a marked improvement. The improvement in ignition quality per unit, weight increment of the ketone cyanohydrin nitrates, whose use is-included by this invention gradually declines somewhat at. proportions in the range of about .0. 5-to .1.0 weight percent. The rate ofdecline in improvement per unit increment is greater at proportions in excess 'of '1.0 weight percent, so that little additional improvement with respect to ignition quality is obtained by the use of proportions in excess of 2.0 percent by' weight. The aldehyde cyanohydrin nitrates whose use is included by this invention differ from the ketone cyanohydrin nitrates in that the improvement in ignition .quality obtained per unit weight increment ordinarily does not begin to decline at proportions belowl.0 percent by weight.- Although the kctone cyanohydrin nitrates are more effective on a weight basis when used in relatively small proportions, it appears that the aldehyde cyanohydrin nitrates produce a greater improvement in ignition .quality on a molar basis. The aldehyde and ketone cyanohydrin nitrates whose use is included by this invention can be prepared in any convenient manner. For example, they can be prepared by e'sterifi'cation of the appropriate cyanohydrin under conditions conventionally employed in esterifying an alcohol with nitric acid, preferably with the use of a molar excess of nitric acid of 70 to percent strength, for example, whitefumingmitric acid. In order to avoid oxidation and decomposition of the cyanohydrin nitrates, the reaction temperature is maintained below ambient room temperature (25 0.), preferably below about 15 (3., but above the freezing point of the mixture. For

example, excellent results are obtained at temperatures in the range of about 5 to 10 C. It is preferred that water of esterification be removed from. the reaction by the useaof a. desiccant, .that is, by hydration of an inert material having an affinity for water, which material can also be a solvent for the reactants. An example of a suitable desiccant, or hydratable material, having solvent characteristics is acetic anhydride. Other desiccants in .clude anhydrous sodium sulfate and calcium chloride. The hydratable material is desirablyemployed in a proportion suflicient to absorb the theoretical quantity, of

water that is liberatable during esterification of the cyanohydrins. When the desiccant itself is not 'a' solvent; an inert water-immiscible solvent such as a saturated hydrocarbon, e.g., hexane or heptane, a halogenated hydrocarbon, e.g., chloroform or carbon tetrachloridqor an ether, e.g., diethyl ether; is preferably employed as a'means of facilitating temperature control. p p The esterification reaction will normally be an tially complete afiter about 3 2 toi about 6' hoi1 'rs, depending upon the reaction temperatureand the strength of the nitrating agent. Excellent results have been obtained with approximately 98 percent nitric, acid, a reaction temperature of about to C. aiida reaction period of 2 w 3 hours H When thereaction is substahtially complete, the reaclIlOD HllXtllle lS quenched by dilution, preferably with water. Higher molecular ht cyanohydrin nitrates, that is, those having a water msoluhilizirighydrocarbon substituent containing '5 or more carbon atoms, willn'orjmal'ly separate from theldi'luted reaction nnx'tu're of own accord and can bc recovered by idecanting. Lower molecular Weight cyanohydrin nitrates are misciole in substantial proportionswith the dilute aqueous acidjand are accordingly conveniently separated by the use of an inert, water-immiscible,organic selective solvent therefor, such as methylene chloride, chlorofdrm, carbon tetrachloridedithyl ether, or the'lik e. I

The preparation of the cyainohydrins from the nitrates are derived is conventional, and as such,'do'"es not form the essence of this inventio'n. v

The aldehyde and ketone cyanohydrin nitrates whose use is included byfthis invention canbe incorporated in the hydrocarbonfu elfo'ils disclosed herein in any suitable manner. These materials are normally "solu'hle'in paraffinic as well as aromatic hydrocarbons" in im roper-neat disclosed herein, and thereforehefincorporated directly in the ifu'el oils. Because off the 'sriiallproportidris' in which the materials disclosed hereiniare used, it y be preferable from the standpoint of'rapidl'y facilitating formation of a homogeneousmixture to employ"such materials inthe form of concentrated solutions of, say, 10 to SOfperc'ent strength in a solvent that'is compatible with the fuel'oil. I

Examples I and II In order to'determine 'thefeffectivenessof"compounds of the class indicatedherein, representative;compounds of such class were prepared and' iucorporatedin varying proportions in several base fuels having redetermine cetane numbers, andth'e thusobtained fuelcompo'sitions were .teste'dto determine their c'etane'numbers 'asmodified by the test compounds. Thebase "fuels, tested were as follows: Test'fuel 1 .was'a commercial, straight run diesel fuel meeting the ASTM requirements for a grade 2-D or medium diesel fuel. Test fuel 2'consisted of ablend of 40 volume percent West Texas straight r unNo. 2 fuel oil distillate, 40 volume percent of a'fluid catalytically Test Fuel 1 Test Fuel 2 Gravity, API 38. 9 32.0 Viscosity, Kinematic, cs. (SUS) 100 F 2. 47 2. 06 (32.8) Flash Point, ASTM D-93, F 152 154 Water and Sediment, Percent trace Carbon Residue, ASTM D-96, Percent 0. 031 Sulfur, ASTM D-1266 0.121 0. 598 Ash, Percent 0. 01 0. 01 Distillation, Gas Oil:

Over Point, F 346 332 End Point, F. 634 596 10% Evap. at, 423 411 v 90% Evap. at, F. 574 546 The cyanohydrin nitrates tested were prepared by nitration of appropriate cyanohydrins. The cyanohydrins from which the cyanohydrin nitrates subjected to testing were derived comprised both a ketone cyanohydrin (acetone. cyanohydrin) and an aldehyde cyanohydrin (2- ethylhexaldehyde cyanohydrin). The respective cyano hydrins were separately preparedby admixture of 0.6 mole ofacetone and freshly distilled 2-ethylhexaldehyde, respectiveiy,'with separate mixtures of 1.0 mole of potassium cyanide in 250 milliliters of anhydrous ether. Acetic acid in the amount of 50 milliliters was added dropwise to each mixture with stirring over a -minute period. The temperatures of the reaction mixtures were held at 15-20 C. during such addition. The reaction mixtures were then stirred for 3.5 hours at C. After standing overnight at room temperature, the solid (potassium acetate) was filtered oil from each mixture and washed with two '50 milliliter portions of anhydrous-ether. The solvent was then removed from the combined filtrate and washingjs. Yieldsapproaching'theoretical were obtained.

. Acetone- :and Z-ethylhexaldehydecyanohydrin nitrates were. then-prepared by nitration of the above-indicated cyanohydrins, using separate nitrating mixtures consisting of ab'out'92.5 grams of white fuming nitric-acid (d='1.49" 1.50). added to about 246 milliliters of acetic'anhydride. External. cooling was employed while mixing to maintain the temperature below C. The nitrating mixtures were chilledto 5 C. and 0.6 mole of the respective cyanohydrins were added in one portion to the. respective nitrating mixtures. The mixtures were'stirred at 8l0 C. for "15 minutes and for 1.5 hours at-room temperature. The reactionmixtures were thenlpoured over separate 500 gram-portions of crushed iceand stirredfor rinehour. Acetone-cyanohydrin nitrate was 'extraeted from. the appropriate reaction mixture. with. three v 150 milliliter'portions of methylene chloride. The -2-ethylhexaldehyde-eyanohydrin nitrate separated spontane- 'ou'slvfrointhe water-aceticacid solution. This product was water-washed, driedover'anhydrous sodium'sulfate 'and'distilledat reduced pressure. The properties of the respective. cyanohydrin nitrates, hereinafter referred .to respectively as' test compounds A and B,-were as follows:

- v Nitrogen, pereiit- B -P 0. "D", n.

"25 0. percent Calculated Found Cicerone Gflnohydfln Ni to (Test 1.127 6451 59-65 (10 mm. 154180 21. 53 120.91 .-.Compoun IA). t 112.. i 2 Eth'ylhc'xaldehyde,, Cyauohydrin Ni- 1. 017' 72.5 17-79 (1.4 mm. 1.4419 14.00 13.76 'trst'e (Test'ConipoundB). Hg). 1 f

'the'hse' fuels "were" as follows: I

' The test fuel '-oil compositions 5 ntaiiiing the evam iiydrih nitrates were tested for' etane number u'nder standard test procedure ASTM D6l3-48T, described' i-n the ASTM Manual of Engine Test *Methods" for Rating 'Fuel'srfo'r' I 2, at-pages"63--71. Briefly; 'this 'te'st involves .r .1 Li

com aring the ignition quality of an unkliow'il test fuel un-' der standard operating conditions with the ignition quality of reference fuel blends having known cetane numbers. The test is carried out in a single cylinderdiesel Good ignition quality will also be obtained with the" following fuel compositions which are examples of other compositions within the scope of this invention:

engine having a continuously variable compression ratio. 5 During the test the compression ratio is varied for the wt 7 test fuel and the reference fuels to obtain a fixed delay Addition Agent meg Base l period, that is, the time interval betweenfuel injection Agent and ignition. When the compression ratio that produces the fixed delay period for the test fuel has been deter- 10 Example S1agld];tydte.cyan0; 1-? 13119891 y in nae. ,ue. mined to be between the compression ratios that will Example mm Benzaldehyde Cyanm Lo Do. produce the same delay period for two reference fuel lI Iydrin(Mandelonitrile) 1 a irate.- blends that differ by not more than 5 octane numbers, the Example 11m pmdmmehme oyamr L0 rating of the sample is calculated by m terpolatlon. The s hydrin Nitrate. v standard reference fuels are prepared from n-cetane and g fg g i fif m -9 a'methylnaphthalene meeting ASTM standards. How- Example 13 oinllllag algsgyge Cya- 1.0 1 Do.

no y ln re 9. ever, secondary, petroleum distillate reference fuels that Example omtonaldehyde Cyanm Lo have been calibrated against the standard blends are norhydrin Nitrate. mally used for routine testing. The operating conditions Exam)! ggg ggtgg L0 of the test are as follows: Example 10. Oyclohexaldehyde Gya- 1.0 Do.

' n 1 11 'o l i ili li ii' o 1 0 D 4- mm e yc opena 8 y 0 Y8- 0. ea p -P- N P nohydrm In ectlon advance, deg. B.T.D.C. 13.0 Examp1e18 Flillftirlrtal Oyanohydrin 1.0 Do.

0 l 8 9. Iniection opemlig pressure? 1500250 Example 19 2-Nonadecanone .Oyano- 1.0 Do. 1 InjeCtlOn quantity, ml./mln. 13.0:02 hydrin Nitrate. Injector pintle valve lift, in 0.005i0.001 Example f gffil f g i Injector water jacket temp, F. 100i5 Example 21"... l-losobugyrlonalpxhtthme 1.0 Do.:

yano y in 1T8- e. Valve clearancqs h 0008:0001 Example 22 Benzophenone Oyano- 1.0 Do, Crankcase lubrlcatlng o1l-- E 1 23 nydrl n glit'atlek t 1 0 D 18.111139 0... 1Cyl! 0 \1 y 0 0118 0. SAE gliade 30 Gyanohydrin Nitrate. vlscoslty, sec., SUV/ 130 F. 185-255 Example r elg ue t azmpe Cyano- 1.0 Do. y 111 1T8 B. 3 Pressure 25 30 Example 25.-. Oyelohexanone Cyano- 1.0 .Do. 011 temperature, F. 135:15 E 1 26 1 tgrlrm lflt aga 1 o D Coolant temperature, F. 212:3 V f, &f Intake air temperature, F. 150.111. 1

The results of the foregoing tests are presented in the r following table: It is emphasized that the presence of both a nitrate Make-up:

Base Fuel, Percent by Vol.-

Test Fuel 1 100 100 100 100 100 100 100 100 100 Test Fuel 2 a 100 100 100 100 100 Addition Agent, Percent by Vol.

(added)- Test compound A 0. 25 0.5 1.0 2.0 0.1 0.25 0.5 1.0 Test Compound B 0. 25 0. 5 1.0 Inspection:

Cetane Number, ASTM 13-013.. 54.0 61.8 03.4 63,6 04.5 35.8 31.7 40.0 43.5 45.8 62.4 55.3 57.9 63.2

From the data presented in the foregoing table it will ester group and a nitrile group is important for the purbe seen that both low and high cetane number fuels are poses of this invention, as this combination results in Improved y incorporation thefelflpf P of the superior ignition quality improvement. For example, P Whose use 18 lflclllded by the lnvenilon- The P P' test compounds A and B were compared for effectiveness erty demonstrated 1n the table appears to be shared by as ignition quality promoters against amyl nitrate, a the other; men bei's of the l:zlas: dlsc losedfbaltholgh n i al alcohol nitrate ignition quality promoter. In these z i f i y equiva a g c P qg tests test compound A, test compound B and amyl nitrate i g ggf ggg f g g; g i ggi g zf f g were incorporated in a diesel fuel having 21 octane number f 1 quality can be obtalned by admixture of the same or g jii fi zg zg g g gi g s; g3 equivalent proportions of other cyanohydrin nitrates dis- 1 He p 6 pc 1 e y o p Po closed herein in the same fuel oils or in other hydro- 9' and 00037? mol 100 of P and carbon fuels disclosed herein. Examples of other fuel the resultlng cetane number Improvement determlned y compositions of the preferred class are as follows: the procedure of ASTM D6l3-48T, described elsewhere Example Example Example Example Example Example 3 4 5 6 7 a Base Fuel:

1D Diesel Fuel. x x x 2-D Diesel Fuel. x x

4-D Diesel Fuel 1: Addition Agent, Percent by Wt;

Acetaldehyde Cyanohydrin Nitrate 0. 0xo0etaldehyde Cyanohydrln Nitrate.-. 0.5 Lauraldehyde Cyanohydrin Nitrate. 0. 5 Diisopropyl Ketone Cyanohydrln Nitrate. 1.0 Butyrone Oyanohydrln Nitrate 0. 75 Laurone Gyanollydrin Nitrate 5 herein; The. respective cetane number improvements, cqngect'edto OQODZSTI mOl/ IOO g. fuel, were as follows:

. From a comparison of the foregoing figures it will be scen that when both a nitrile and a nitrate group are attached"to'the same 'carbon' atomysuperior results are obtained.

ASTM grade 1-D, 2' 1) and 4-D diesel fuels-are define d in ASTM Standards on Petroleum Products and Lubricants, November 1956; under ASTM designation D975- 53T. Number 12 fuel-oils: are: defined in the same reference under ASTM designation1D39648T.

The'hydroca'rbon' fuel oil compositions of this invention may contain in addition to' the cyanohydrin nitrates disclosed herein other'additio'n agents'adapted to improve the oils in one. or more respects. For example, the fuel oil compositions of this invention may also contain oxidation inhibitors, corrosion" inhibitors, detergents, sludge inhibitors, anti foam agents andother ignition quality or combustion improvement agents.

It will be apparent to those skilled *in'the art that many modifications' and variations of'the' invention as'described herei-n'can be made without departing'from-the'spiritor scope thereof; Accordingly, only such limitations should be imposed as, are indicated-in the 'claims appended hereto.

I claim: i

l. fuel? oil composition comprising a major amount substituent a hydrocarbon radical containing 1 to 18 car bon atoms and as the other a member selected, from thegroup consisting of a hydrocarbon radical of the same kind and hydrogen.

2. The-compositionof claim 1 where the small amount is about 0.05 to 2 percent by weight of the composition;

3. The eomPQ$ition of claim 1 where the hydrocarbon radicalis an alkyl group that contains 1 to 12 carbon atoms.

4. A fuel oil compositioncomprising a major amount,

of a diesel fuel and a small a mount,-suflicient to improve the ignition" quality of said oil, ofacetone cyanohydrin nitrate,

5: The composition of claim 4, where said smallamount is about 0.-5'to 1 percent by weight ofthe composition. 7 1 v 6. A fuel oil composition -comprisingia major amount of a diesel'fuel and a small-amount, sulficient to improve the ignition quality ofsaidoil, of 2-ethylhexaldehyde cyanohydrin' nitrate.

7. The composition of claim 6, where said small amount is about"0;5 to2perc'ent by weight of the com-' position.

References Cited in the'file of'this patent UNITED STATES PATENTS OTHER-REFERENCES fi'r reans of Improving Ignition Quality of Diesel Fuelsl by"Nygoard et'al., Journal of the Institute of Petroleum Technology, vol. 27, pp. 3'48368', October 1941-.

Claims (1)

1. A FUEL OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF A HYDROCARBON FUEL OIL AND CONTAINING A SMALL AMOUNT, SUFFICIENT TO IMPROVE THE IGNITION QUALITY OF SAID OIL, OF A CYANOHYDRIN NITRATE DERIVED FROM A MEMBER OF THE GROUP CONSISTING OF ALDEHYDES AND KETONES HAVING AS ONE SUBSTITUENT A HYDROCARBON RADICAL CONTAINING 1 TO 18 CARBON ATONS AND AS THE OTHER A MEMBER SELECTED FROM THE GROUP CONSISTING OF A HYDROCARBON RADICAL OF THE SAME KIND AND HYDROGEN.