CA1284583C - Fuel compositions - Google Patents

Abstract

ABSTRACT
FUEL COMPOSITIONS

Coking in and around the injector nozzles of indirect injection compression ignition engines is reduced by means of distillate fuel with which has been blended suitable concentrations of:
(a) organic nitrate ignition accelerator, and (b) hydrocarbyl-substituted succinimide, or (a) organic nitrate ignition accelerator, (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens, and (d) N,N'-disalicylidene-1,2-diaminopropane, or (b) hydrocarbyl-substituted succinimide or succinamide (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens, and (d) N,N'-disalicylidene-1,2-diaminopropane.

Also described are such additive mixtures for use in distillate fuels in amounts sufficient to reduce the coking tendencies of such fuels when used in the opera-tion of indirect injection compression ignition engines.

Description

3 4 5 ~ 3 Thi~ is a divisional application of copendîng application serial no. 470,058, filed Decernber 13, 1984.

_UEL COMPOSITIONS

Compression ignitioll fllel compositions alld ad~ ive mixtures oE or-3allic nitrat:e i~nitioll accelerator alld hydrocarbyl-substituted succillimi.de, in 5 amoullts sufficient to resist the coking tendellcies of coml)ression iynition fuel cornpositions when used in the operation oE indirect injectioll diesel engines.
l`hrottlillg diesel no%%les have recerltly come into widespread use in indirect injection automotive and 10 ligllt-duty diesel truck engines, i.e., compression ignitioll engines in whicll the ~uel is injected into and ignited in a prechamber or swirl chamber. In this way, the Elame Eront proceeds Erom the prechamber into the larger cornpression chamber where the cornbustion is com-15 pleted. Engines designed in this manner allow ~orquieter and smoother operation. The Figure o the Drawing illustrates the geometry oE the typical throttling diesel noz%le (oEten reEerred to as the "pintle nozzle" ) .

UnEorturlately, the advent oE such en~ines has giJell rise to a new problem, that o~ excessive cokinc3 on ~ ~458~3 the critical sur~aces o~ the injec~ors that inject Euel itltO l:he prechalnber or swirl charnber of the engine. In varticular and with referellce to tlle Figure, the carbon tends to ~ill in all o~ the available corners and 5 ~surEaces o~ ~he obturator 10 and tlle form 12 until a smoo~ )rofile is achieved. The carnon also tends to block the drille(3 oriEice 1~ in the injector ~ody 16 an(3 fill UL~ to the seat 18. In severe cases, carbon buil-3s up on the ~orm :L2 and tlle obturator lO to such an extent 10 that it interferes with the spray pattern of the fuel iSSUill9 from around the perimeter oE orifice 14. Such carbon build up or coking oEten results in such undesirable consequences as delayed fuel injection, increased rate of uel injection, increased rate of lS combustion chamber pressure rise, and increased engine noise, and can also result in an excessive increase in emission from the engine of unburned hydrocarbons.
~ ll)ile low fuel cetane number is believed to be a major contributing factor to the coking prohlem, it is 20 not the only relevant factor. Thermal and oxidative stability (lacquering tendencies), fuel aromaticity, and such Euel characteristics as viscosity, surface tension and relative density have also heen indicated to play a role in the coking problem.
~n important contributioll to the art would be a fuel composition which has enhanced resistance to coking 1~3458 3 tendencies when employed in the operation of indirect injection diesel engines.
In accordance with one of its embodiments, this invention provides distillate fuel for indirect injection compression ignition engines containing at least the combination of (a) organic nitrate ignition accelerator, and (b) hydrocarbyl-substituted succinimide or succinamide, or the combination of (a) organic nitrate ignition accelerator, (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens and (d) N,N'-disalicylidene-1,2-diaminopropane, or the combination of (b) hydrocarbyl-substituted succinimide or succinamide, (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens and (d) N,N'-disalicylidene-1,2-diaminopropane, said combinations being separately present in an amount sufficient to minimize coking, especially throttling nozzle coking, in the prechambers or swirl chambers of indirect injection compression ignition engines operated on such fuel.
Another embodiment of the present invention is a distillate fuel additive fluid composition comprising (a) oryanic nitrate ignition accelerator, and (b) hydrocarbyl-substituted succinimide or succinamide, or (a) organic nitrate ignition accelerator, (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to lO nitrogens and (d) N,N'-rn/

458~3 disalicylidene-1,2-diaminopropane or (b) hydrocarbyl-substituted succinimide or succinamide, (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens and (d) N,N'-disalicylidene-1,2-diaminopropane in an amount sufficient to minimize the coking characteristics of such fuel, especially throttling nozzle coking, in the prechambers or swirl chambers of indirect compression ignition engines operated on such fuel.
Since the invention also embodies the operation of an indirect injection compression ignition engine in a manner which results in reduced coking, a still further embodiment of the present invention is a method of inhibiting coking, especially throttling nozzle coking, in the prechambers or swirl chambers of an indirect injection compression ignition engine, which comprises supplying said engine with a distillate fuel containing at least the combination of (a) organic nitrate ignition accelerator, and (b) hydrocarbyl-substituted succinimide or succinamide, or the combination of (a) organic nitrate ignition accelerator, ~c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens and (d) N,N'-disalicylidene-1,2-diaminopropane or the combination of (b) hydrocarbyl-substituted succinimide or succinamide, (c) hydrocarbyl amine having from 3 to 60 carbons and from 1 to 10 nitrogens and (d) rn/

~,N'-disalicyclidene-1,2-diaminopropane, said comb.ina-t;ons being separately present in an ainount su~ficient to millimize such coking in an engine operate~ on such ~uel.
A feature o~ this invention is that the combillation oE additives utilized in its practice ls capable o~ suppressing co~ing l:endencies o~ Euels used to operate indirect injection compression ignitioll ellgines. SUCI1 behavior was exhibited in a series oE
stan(lard engine dynamometer tests conducted as des-cribed in Examples I, II and III hereinafter.
~ wide variety of organic nitrate ignition accelerators, compollent (a) "nay be employed in the fuels of this invention. Preferred nitrate esters are the aliphatic or cycloaliphatic nitrates in which the aliphatic or cycloaliphatic group is saturated, con-tains up to about 12 carbons and, optionally "nay be substituted with one or more oxygen atoms.
Typical organic nitrates that rnay be used are 20 methyl nitrate, ethyl nitrate, propyl nitrate, isopropyl nitrate, allyl nitrate, butyl nitrate, isohutyl nitrate, sec-butyl nitrate, tert-butyl nitrate, amyl nitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate, hexyl nitrate, heptyl nitrate, 2-heptyl nitrate, octyl 25 nitrate, isooctyl nitrate, 2-ethylhexyl nitrate, nonyl nitrate, decyl nitrate, undecyl nitrate, dodecyl .

~.

~458~

ni~rate, cyclopentyl nitrate, cyclollexyl nitrate, methyl-cyclohexyl nitrate, cyclododecyl nitrate, 2-ethoxyethyl nitrate, 2-(2-ethoxy-ethoxy)ethyl nitrate, tetra-hydro~uranyl nitrate, and the like. Mixtures of such Inaterials Inay also be used. The preferred i~nitioll accelerator Eor use in t~le ~uels oE this invention is a Inixture oE octyl nitrates available as an article oE
comlnerce ~roln Ethyl Corporation under the trade mark DII-3 ignition improver.
~rhe hydrocarbyl-substituted succinimides, colnponellt ~b) of the fuels of this invention, are well knowll. They are readily made ~y ~irst reacting an oleEillically unsaturated llydrocarbon of the desired molecular weight with maleic anllydride to form a hydrocarbyl-substituted succinic anhydride. Reaction telnpcratures oE 100-250C are used. ~ith higher boilinc~
oleEinically-unsaturated hydrocarbons, ~ood results are obtailled at 200-250C This reaction can be promoted by the addition oE chlorine. Typical oleEins include cracked wax oleEins, linear alpha olefins, branched chaill alplla oleEins, polymers and copolymers of lower oleCills. These include polymers oE ethylene, pro-pylelle, isobutylene, l-hexelle, l-decene and the like.
UseEul copolylners are ethylene-propylene copolymers, ethyleile-isobutylene copolymers, propylene-isobutylene copolylners, ethylelle-l-decene copolylnees and the like.

`

~4~8 3 llydrocarbyl substituel1ts have also been made ~ror olel~in terpol;~mers. Very use~ul products have been made f etl1ylene-C3 12 alpl1a olel~in - C5~12 col1ju(Jclted diene terpolylners; SllCil as ethylel1e--5 propyl ne-l,4~11e~adiene terpolymer; etl1ylel1e-propylel1e-],5--cyclooctadiene terpol-ymer; ethylene-propylene--norl~orm1ene terpolymers and the like.
Of the foregoin-3, by Lar the most useEul hydro-carbyl substituents are derived Erom butene polymers, lO especially polymers of isobutylene.
The molecular weight of the hydrocarbyl sub-stituent can vary over a wide range. It is desirable that the liydrocarbyl group have a moleclllar weig11t of at least 500. Although there is no critical upper limit, a 15 preerred range is 500-sno,ooo number average molecular weig11t. The more preferred average molecular weight is 700-5,000 and most preEerably 900-3,000.
Ilydrocarbyl-substituted succinimides and succinalnides are made by reaction of the desired 20 hydrocarbyl-substituted succinic an11ydride with an amine havin~ at least one reactive hydrogen atom bonded to an amine nitrogen atom. E:~amples oE these are methyl anine, dimethyl arnine, n-butyl arnine, di-(n-dodecyl) alnine, N-(aminoethyl) piperidine, piperazine, ~1-(3-amino-25 L)ro~yl) piperazine, and the lilce.

~L~f3458~3 Preferably, the amine has at least one reactivepriilary aTnine group capa~le o~ reacting to ~orm ~he preerred succinimides. ~xalnples oE such primary amines are rl-octyl amine, N,N-dimetll-yl-1,3-propane diamine, I~-(3-~aminopropyl) piperazine, 1,6-hexane diamine, alld the ~ike.
Ilydroxyalkyl amines can also be use-3 to make the suc_iniinide-succinaJnide compol-ents of the invention ~hicll contain some ester grouus. These amines include 10 ethallo]. amine, diethanol amine, 2-hydroxypropyl amine, ~l-hydroxyethyl ethylenediamine and the like. Such hydroxyalkyl a-nines can be rnade by reacting a lower alkylene oxide, such as ethylene oxide, prol~ylene oxi-3e or butylene oxide with a:nmonia or a primary or secondary alnine such as ethylene diamine, dethylene triamine, tri(~ llylene tetramine, tetraetllylellepentamine an~ the ]ike.
A more preferred class oE primary amines used to make tlle succinimide, succinamide or mixtures thereoE
are the polyalkylene amines. These are polyamines and mixl:ures of polyamines whicll llave the general formula H2N-~ R - N~ nH

458~3 wl~ereill ~ is a divalent aliphatic hydrocarbon group having 2-4 carbon atoms an(~ n is an integer from 1-10 inclu~ g mixtures of sucll polyalkylene amines.
In a highly preferred embodimellt, the poly-alkylene a,-nine is a polyethyleneamine containillg 2-6 etllylelleamine Ullits. T},ese are eepresented by tlle above ~oLmula in whicll R is tlle group -CH2Cl~2- and n has a value of 2-6.
The alnine used to make the succinimide, ~;uccinaJnide or mixture thereof need not be all amine.
mono or poly-hydroxyalcohol may be included in the reaction. Such alcohols can be reacted concurrently with the amine or tlle two alcohol and amine may be reacted sequentially. UseEul alcohols are methallol, ethallol, n-dodecanol~ 2-ethyl hexanol, ethylene glycol, propylene glycol, diethylene glycol, 2-ethoxy ethanol, trilnethylol propane, pentaerythritol, dipentaerytllritol arld the like.
Use~ul amine-alcohol products are described in U.S. 3,184,474; U.S. 3,576,7~3; U.S. 3,632,511; U.S.
3,804,763; U.S. 3,836,471; U.S. 3,936,480; U.S.
3,9~ 00; U.S. 3,950,341; U.S. 3,957,854; U.S.
3,957,855; U.S. 3,991,098; U.S. 4,071,548 and U.S.
4,173,5~0.
The reaction between the hydrocarbyl-substituted SUCCilliC anllydride and the amine can be carried out by ~ 458~3 mixil~g the components and heating the mixture to a temperatllre l~igh enougl~ to cause a reaction to occur but not so higll as to cause 3ecolnposition o~ the reactarlts or products or the anhydride may be heated to reaction ter;ll?irature and tlle arnine added over an extende(1 peL iod. A useful ternperature is 100-250C. Best results are obtained by conductill~ tlle reaction at a temperature high enough to distill out water ~ormed in tl-e reaction.
~ preferred succininide-succinamide cornponellt is available as an article oE commerce froln the Edwin Cooper Company under the tr~de mark IIITEC E-6~4. This product comprises a mixture of active ingrediellts and solvent. Tllus, whell I~ITI~C~ E-644 is used as component (b) in formulating the ~uels of this invelltion, the product as received should be used at a concentration o~
at least about 40 YTB (pounds per thousarld barrels) O.11~36 grams per liter - to insure that the fillished blend contains an adequate quantity of the foregoing 20 succinimide-succina1nide ingredient although smaller alnounts may be successfully emoloyed.
The nitrate ignition accelerator--cornponent (a)--should be present in an amount of at least 100 to 1000 PTB (pounds per thousan~ barrels) - 0.2859 to 2 859 grans per liter - of the base fuel. Preferably, the ~4~8~

concelltration of the ignition accelerator is 400 to 600 PTl3 (1.1~36 to 1.715~ gralns per l.iter).
It is not believed that there is anytlling critical as regards the Inaximum arnoullt oE cornponellts (a) and (b) used in the Euel. Tl1US, the maxilnum amount oE
tl~ese components will probably ~e governed in ally qiven sitllatiotl by matters oE clloice and economics.
The coking-inhibiting components (a) and (b) oE
the invention can be added to the Euels by any means k~lown in the art Eor incorpoeatillg small quantities of additi.ves into distillate Euels. Components ta) and ~b) can be added separately or they can be combined and added together. It is convelliellt to utilize additive fluid Inixtures whicll consist of organic nitrate ignition accelerator and hydrocarbyl-substituted succinimide-succinamide agents. These additive fluid mixtures are added to distillate Euels. In other words, part oE the present invention are coking inllibiting fluids whicl comprise organic nitrate ignition accelerator an~
llyc3rocarbyl-substituted succinirnide-succinaJnide.
U.se oE such fluids in addition to resulting in great convenience in storage, handlin~, teansportation, blellding with fuels, and so Eorth, also are potent concelltrates which serve the Eunction oE inhibiting or min.irni~ing the coking characteris~ics o.E compres.sion 4S~'3 i911i~iOIl distillate fuels used to operate inclirect compressioll ignition engines.
In these Eluid compositions, the amount of com-pOllell~S (a) and (b) can vary widel~. In general, the fluid compositions contain 5 to 95~ by weigllt of the organic nitrate igllitioll accelerator componellt and 5 to 95~ by weight oE the hydrocarbyl-substitute(i succini,nide-succinamide compollellt. Typically, Erom .01 by weight up to 1.0% by weight oE the combillation will be suEficiellt to provide good coking-inhibiting proper-ties to the distillate fuel, A preEerred distillate fuel composition contains rom 0.1 to 0.5~ '~y weigllt of the combination containing from 25~ to 95% by weight of the organic nitrate ignition accelerator and from 75~ to 5% by weigllt of the hydrocarbyl-substituted succinimide-succinamide component The additive Eluids, as well as the distillate fuel compositions of tlle presellt inventioll may also contain other additives such as, corrosion inhibitors, antioxidants, metal deactivators, detergents, cold ~low improvers, inert solvents or diluents, an~l the like.
Accordingly, a more preferred distillate fuel composition includes a hydrocarbyl amine in combinatio witll l;he present additives.

458~

~ hile a variety of hydrocarbyl arnines rnay be used in tlle ~uel compositiolls oE this invention, a primary aliL)Ilatic amine, the aliphatic grouu of whicil is tertiary, e.g., an amine of t}le Eorlnula:

i~-NI~ 2 whereill R is one or a mixtllre of tertiary aliphatic grollps containing 8 to 18 or more (preferably 12-16) carboll atorns is preferred. Most preferably, these tertiary aliphatic groups are tertiary alkyl groups. It 10 is also preEerred that hydrocarbyl amine component (c) include in addition to the above-depicted amine one or more llydrocarbyl amines difering therefrom.
U.S. Pat. ~o. 3,9n~,2l5 gives a description oE
the various hydrocarbyl amines having from 3 to 60 carbolls and ~rorn 1 to 10 nitroyells whicll may be employed in t!le fuels of this invention. A few additional exam~les of desirable amines include 2,6-di-tert-butyl-~-dilnethylamino-p-cresol, ~-cyclohexyl-N,~l-dimethylamine, and N-alkyl,N,N-dimethylamilles in which 20 the alkyl group is one or a combillation of alkyl groups preEerably ~laving 8 to 18 or more carbon atoms.
~ particularly preEerred llydrocarbyl arnine is available commercially ~rom the Rohrn and llaas ~ompany d(r the trade mark Primene 81R. The Primene 81R*is * tra~le mark s~

believed to be a mixture oE primary aliphatic amines inWjliCIl the aliphatic groups are predomillantly C12 and Cl~ tertiary alkyl groups.
~rhe ~uels oE this invention should contain at least 1.5 to ~0 PTs (0.00429 to 0.1143 gralns/litec oE
col.l?ollent (c), the hydrocarbyl amine.
~ ccordillyly, another embodiment oE t:he present invention is distillate Euel for indirect injection com,~ression igllition engines containillg at least the combination oE (a) organic nitrate ignition accelerator, (b) hydrocarbyl-substituted succinimide, and (c) hyd[ocarbyl amine, said combinatioll being present in an amount suEEiciellt to rninimize coking, especially thro~tling nozzle coking in the prechambe~s or swirl chamb~rs in indirect injectioll compression ignition engilles operated on such Euel.
Also included as a urther embodirnent o~ the illvention is a distillate uel additive composition comprising (a) or~anic nitrate i~nition accelerator, (b) llydrocarbyl-substituted succinimide an-3 (c) hydrocarbyl amine in an arnollnt suEficient to mini.mize the coking characteristics of such Euel, especially throttling nozzle coking in the prechambers or swirl chambers in in(lirect injection cornpression ignition en.3ines operated ~5 on .such Euel.

1~345~3'3 In gelleral, these additive fuel compositions will contain as mllch as sn~ by weight of the combination oE
orgallic nitrate ignitioll accelerator and llydrocarbyl-sul~stituted succinimide and up to 50~ o the hydrocarbyl alnine or other additives wllen they are present.
In a still ~urtiler elnbo(3i.ment of the invention there is provided a method oE inhibiting cokiny, especially throttling nozzle coking in the prechambers or swirl chalnbers oE an indirect injection compression 10 igllition engine which comprises supplyin~ said engine Wit]l a distillate fuel containing at least the com-bination of (a) organic nitrate ignition acc~lerator, (b) hydrocarbyl-substituted succinimide alld (c) hydrocarbyl amine, said co!nbination being present in an amoullt suEicient to Ininirnize such coking in an engine operated on such fuel.
~ nother additive whicll can be used to advantage in the present inVention i5 a Inetal deactivator.
E~amples oE these are salicylidene-o-aminophenol, 20 disalicylidene ethylenediamine and disalicylidene propylenediamine. ~ particularly preferred rnetal deactivator is ~,N'-disalicylidene-1,2-diaminopropalle (80 weigllt percent active in 20 ~eight percent toluene solvellt) which is available as an article oE colnrnerce ~rom Ethyl Corporation under the trade mark `'Etllyl" MDA.

5~3~

The Euels of this invel-tion should eontain at lea.st 0.2 to 5 pTs (0.00572 to 0.012 grams per liter) o~
compollent td), the metal deactivator, pre~erably N,N'-disc~licylidene-1~2-dialninopropalle.
~ccordingly, another embodiment oE the present invelltion i.s distillate fuel for ;.ndirect injection compressioll ignitioll enc3ines containing at least the combination oE (a) organie nitrate ignition aeeelerator, (b) hydroeaLbyl-substituted sueeinimide, (e) hydroearbyl 10 a-nill~, and (d) N,N'-disalicylidene-1,2-diamillopropane, said combination being present in an amount suf~ieient to minimize coking, expeeially throttling nozzle eoking in the preehambers or swirl ehambers in indireet injection eompression ignition engilles operated on sueh 15 ~Uel.
~ lso ineluded as a Eurther embodiment oE the invention is a distillate Euel additive eo~nposition comprising (a) organie nitrate ignition aeeelerator, (b) hydroearbyl-substituted sueeinimide, (e) hydroearbyl 20 amill~, and (d) N,N'-disalieylidene-1,2-diaminopropane in an al~oullt su~ieient to minimiæe the eoking eharae-teristies oE suell Euel, espeeially throttlinc~ nozzle eoking in the preehalnbers or swirl ehambers of indireet injection compression ignition engines operated on sueh 25 fu~ls.
In general, these additive fuel compositions eontain as mueh as 50~ by weight of the combina - n . ~

~4S~

or~anLc nitrate ignition accelerator and hydrocarbyl-sub.stituted succinimide-succinamide and up to sn~ of the combination oE hydrocarbyl amine an-l N,N'-disalicylidene-1,2--diaminopropane or otiher additive.s when they are 5 ~reienl:.
In a still Eurther elnbodi!nent of the invention there is pLovide~ a met)lod o~ inllibitillg coking, especially throttling nozzle coking in the prechambers or swirl chambers in an indirect injectioll compression L0 i'.JIlitiOIl enyi.ne which cornprises supp.lying said engille with a distillate uel containin~J at least the com-bincltioll oE ~a) organic nitrate ignition accelerator, (b) ilydrocarbyl-substituted succinimide, (c) hydrocarbyl amine and (d) N,~'-disalicylidene-1,2-diaminopropane, 15 said combination being presellt in an amount to minimize such coking in an en-~ine operated on such Euel.
In another embodiment of t]liS invention, the coking-i~ ibiting componellts (a), (c~ and (d) of the invelltion can be added to the .Euels by any means known in the art Eor incorporating srnall quantities oE
additives into distillate Euels. Compollents (a), (c) and (d) can be added separately or they can be combined and added togetller. It is convenient to utilize addil:ive Eluid mixtures ~/llich consist oE organic nitrate ignition accelerator, hydrocarbyl amine and metal deactivator agents. These additive Eluid mixt:ures are 458'.~

adde~1 to distillate Euels. In other words, part of thc presel1t invention are coking inl1ibitil1g Eluids which coml)rise organic nitrate i911itiOIl accelerator, hydrocarbyl amine having Eroln 3 to 60 carbons and Erom l to 10 nitrogens and metal deactivator, preEerahly N,~'-di:-;a,licylidene-l,2-~:~iaminopropalle.
In these E1uid cornpositions, the alnollnt oE
compol1ents (a), (c) and (d) can vary widely. In gel1era1, the E1uid compositions contain 10 to 97.9~ by 10 weigllt of the organic nitrate ignition accelerator compol1ent, 2 0 to 75~ by weight o~ the hydLocarbyl amine and O.l to 15% by weight metal deactivator. Typically, from 0.01~ by weight up to 1.0~ by weight of the combil1ation of the components (a), (c) and a(d) will be 15 sufEicient to provide good coking-inhibitil1g properties to tl1e distillate fuel. ~ preEerred distillate ~uel composition contains Erom O.l to 0.S% by weight o~ the com'~il1ation containil1g Erom 50 to 97.9% b~ weight oE the orgal1ic nitrate ignitiol1 accelerator, from 2 0 to ~5~ by 20 ~lei~ht oE the hydrocarbyl amine and Erom 0.1 to 5. n~ by weigllt of the metal deactivator component.
In another embodiment of tl-is invention, the c~i;in-J-inhibiting components (b), (c) and (d) of the invel1tion can be added to the Euels by any means know 25 in the art for incorporating small quantities oE
additives into di~stillate Euels. Components (b), (c) 58'3 and (d) can be added separately or they can be combined alld a(~ded tO9etiler. It is co~venient to utili~e ad(~itive fluid mixtures wllich COllSiSt oE hydrocarbyl-sub~tituted succinimide-succinamide agents, hydrocarbyl 5 anline and ~,N'-disalicylidene-1,2-diaminopropane. rrhese a~itive Eluid mixtures are ad-3ed to distillate fuels.
In (~tller word.~, part of tlle present invention aee coking inhibiting fluids which comprise hydrocarb-~l-substituted succinimide-succinamide, hydrocarbyl amine having from 3 10 to G0 carbons alld 1 to lO nitrogens, and metal deacti-vator, preferably N,N'-disalicylidene-1,2-diaminopropane.
In these fluid compositions, the amount of compollellts (b), (c) and (d) can vary widely. In general, the fluid compositions contain lO to 97.9% by 15 weight oE the hydrocarbyl-substituted succinimide-succinamide component., 20 ~o 75% by weight of the hydrocarbyl amine and n. l to 15% by weight metal deactivator. Typically, Erom 0.01~ by weight up to l.0 by weight of the combination will be sufficient to 20 provide good coking-inhibiting properties to the dis-tillate fuel. A preferred distillate fuel composition contains from 0.1 to 0.5% by weight of the combinatio containing ~rom 50~ to 97.9~ by weight of the hydro-carbyl succini.mide-succinarnide componellt and from 2.0 25 to 45~ by weigllt of the hydrocarbyl amine and from n.
to 5.0~ by weight of the metal deactivator, preferably N,~'-disalicylidene-1,2-diaminopropane.

5~3~3 The practice and advantages o~ t)liS invention will become still further apparellt Erom the ~ollowillg illu!,trative example.
EXAMPLE l -In order to determine the e~fect oE the fuel comi?ositiolls of the present invelltion on the col;ing tendellcy of diesel injectors in indirect injection compression ignition engines, use was made of a com-lnercial diesel engine oL~erated on a coking test cycle develoued by Institute Francais Petrole and as prac-ticed by Peugeot .S A. The arnount of coking together with a quantitative indication oE the adverse conse-quellces oE such coking \~as determined by means of (i) in-jector air flow per~ormance, (ii) emission o~ unl~urlled hydrocarbons, (iii) engine noise, and (iv) injector deposit ratinc3s. The engine employed in the tests was a 19~2 Peugeot 2.3 liter, ~-cylinder, turbo-charged XD2S
diesel engine connected to a Mid~est dynamometer through an engine clutch This enyine is equipued with Bosch injectors positioned within prechalnbers, and is deemed representative of the indirect injection compression ignitioll engines widel-y used in ~utomobiles and light-duty trucks.
The base fuel employed in these engine tests ~as a commercially-available diesel fuel havillg a no.nillal cetane rating oE 42. FIA analysis indicated the fuel ..

~4S8~3 was composed by volume oE 31.5g aromatiçs, 3.0~ olefins and G5.5~ sa~urates. Its distillation range (~ST~l D-158) ~,~as as ~ollows:

Barometer 29.46 incnes oE 1l9 (0.9987 Bars) Initial 406F - 207.78C
_aporated at F - at C
~39 226.11 450 232.22 456 235.56 463 239.4~
480 248.~9 499 259.44 521 271.67 545 285.0 572 300.0 - 503 317.22 6~1 327.22 643 339.~4 678 358.89 Final 678F 358.89 Xe c ove ry 97.5%
~e s i ~u e 2.5 I,oss None ~3458`3 Other inspectioll data on the base Euel were as followc;
Kinelnsltic Viscosity, (ASTM D~945) . . . 3.50 Centi-stokes, 40C
Pour Point (ASTI~ D - 97) .. . . . . . . .-26C
Cloud Point (~ST~ D-97) ................. 33C
Flash Point (AsrrM D-93) ................. 91~C
Stearn Jet Gum . . . . . . . . . . . . . 2.4 mg/100 )nl ~niline Point (ASTM D-611). . . . . . . 143.4F (61.89C) 10 Total Sulfur. . . . . . . . . . . . . . 0.41 wt.
Ramsbottom Carbon, ~ (ASTM D-524~ . . . 0.1460 on 10 Residuum Gravity (ASTM ~-287). . . . . . . . . . 31. 8 API
Speci~ic Gravity @ 25C . . . . . . . . 0.86 Cetane rating . . . . . . . . . . . . . 41 A test bLend was prepared Erom this base fuel (Fuel A). Fuel A contained a combinatioll oE (ij 506 PTB
~ 7 grams/liter) of mixed octyl nitrates (a com-mercial product available Erom Ethyl Corporation under 20 tile tr~de mark DII-3 Igllition Improver), ( ii) 41 PT3 (0.117 gram/liter) of HITXC~ ~-G44, a product oE ~dwin Cooper, Inc., believed to he a hydrocarbyl succinimide-succinamide made by reacting two moles oE a polyisobutenyl succinic anhydride (PIBSA) with one mole o~ a polyethylene amine mixture llaving an average composition correspondillg to tetraetllylene pentamine, 4~8 3 (iii) 14 PTB (0.04 grams/liter) o~ a hydrocarbyl amine availahle commercially from Rohm alld Haas Company url-ler the tracle mark Primelle 81R and (iv) 1.7 P'1'13 (O.On486 grams/liter) oE Ethyl* Metal neactivator, a product oE
Ethyl Corporation, the active ingrediellt o~ wllicll is N,l~ disalicylidelle-1,2-dialninopropane. The ;nanu-Eacl,urer gives the ~ollowing typical properties ~or its HIT~C~ E-644 product:

~ppearance ~ark brown Viscous li~luid Nitrogen, wt. ~ 2.0 Speci~ic Gravity at 60/60F 0.928 Viscosity at 210F, cs 3~0 (98.890C) The Primelle 81R*i~s believed to be a mixture oE

primary aliphatic amines in ~hich the aliDhatic groups are predominall~ly C12 and C14 tertiary alkyl yrouUs-The manuEacturer gives the ~ollowing typical properties for its Ethyl* metal l)eactivator:

Form Li~uid Color Amber Density, at 68F
g/ml 1.0672 lb/gal ~.91 ~ctive ingredient, wt % 80 * trade mark ~3458'3 .

- 2~ -Solvent vehicle (toluene), wt % 20 Llash point, open cup, F 84 (28.89C) Fire point, F 100 (37.7~C) Solubility In gasoline (Typical) Saturated solulion contains 9 '1 In water, wt. ~ 0.04 Shell Rotella T*, an SAE 30, SF/CD oil was used as the crankcase lubricant.
Before starting each test, new Bosch ~NOSD -1510*nozzles were installed using new copper gaskets and flalne rin~s. The Cuel line wa~s Cluslled witll the new test fuel composition to be tested and the Euel Cilter bowl and Cuel return reservoir were emptied to avoid additive carry-over Crom test-to-test.
At the start of each test, the engine was opecated at 1000 rpm, light load ~or 15 minutes. AEter this warm-up, the engine was subjected to the followillg autolnatic cycle:

Event R Beam Load Minutes EGR

1 750 0 4 o~f 2 2750 12.0 6 on 3 1500 6.2 6 on ~ ~000 16.2 4; o~f * trade Inark ~3458`3 The above 20-minute cycle was repeated 60 times and the tes~ was completed by running the engine at idle for allother 30 minutes. The total elapsed time was thu 20.5 llours per test.
Wllell passin~ from one event to the next event in the above cycle, some tilne, oE course, was re~uired to enal)le the engine to accelerate or decelerate ~rom one speed to the next. Thus, Inore speciEically, the al~ove cycle was proyramlned as Eollows:
lOSegmellt Seconds rpm ~eam Load 3 3* 2500 12 4 7* 2750 12 6 3* 2275 6.2 7 7* 1500 6.2 8 330 1500 6.2 9 3* 3500 16.2 2010 7* 4000 16.2 11 230 ~000 16.2 12 .3* 2000 0 13 7* 750 0 25 * l~epresents two mode periods ~or acceleration or deceleration to the next condition.

5~3 3 'Iydrocarbon exhaust emissions were measured at the start oE each test (after the Eirst 20-minute cycle), at the 6-hour test interval .~nd at tlle end of tl-e test. These measurements were ma-3e at 750t 1000, and 1400 rpm idle. Noise level rea-lings were made at a location tllrte ~eet Eroln the en~iTle exhaust side. The rneasurelllents were made at the start and at the en~ oE
the test ~hile operatillg at three idle speeds, viæ., 750, 1000 and 1400 rpm.
10 AEter the test operation, the injectors were care{ully removed from the engille so as not to disturb tlle deposits formed thereon. Measurements were made o~
air Elow through each no~zle at diEferent pintle lifts, and pintle deposits were rate~ using the CRC deposit rating system.
The most significallt test results are ~iven in Table I, in wllich air flow is expres:,ed as CC/lllill and hydrocarbon emissiolls as ppm.
TABLE I

.~ir Flo~ Pintle Obturator llydrocarbon @ 0.1 mm Deposits l~oise, ~B Emissions Fuel Lift (10 = clean) EOT* INC~. EOT* Incr.
Base 36 8.0 83.8 3.0 577 406 A 38 8.6 81.4 1.9 275 143 * Va]ue at end of test; the increase (Incr.) shown is in comparison to the vallle at start of test.

. ., 4~

The results prQsented in Tabl~ I show that tllere were less coking deposits (hi~3her air flow rate and fewer deposits), less engine noise and le.ss hydrocarbo emissions with Fuel A, tlle Euel of the invention, .~s comL)ared to the Base Fuel.
E~:~AMPLE :tI
~ test blend was prepared Erom the base fuel o Example I ~Fuel B). Fuel ~ contained a coml>ination o~
(i) 50G PTB (1.447 grams per liter) of mixed octyl 10. nitrates (a cornmercial product available from Ethyl Corporation under the trade mark DII-3 Ignition Improver), (ii) 13.2 PTB (0.0377 grams per liter) of a hy(3rocarbyl amine available commercially from Rohm and Haas Company under the trade mark PriJnene 81R and (iii) 1.7 PTB (0 00486 grams per liter) of Ethyl Metal Deactivator, a product of Ethyl Corporation, the active ingredient of which is N,N'-disalicylidene-1,2-diamino-propane.
The test engine was operated under the same con-ditions as those of Example I.
The most significant test results are given inTable II, in which air flow is expressed as cc/min and hydrocarbon emissions as ppm.

* trade mark .

~ 45~

- 2~ ~

T~BLE II

Air Flow Pintle Obturator ~ydrocarbon Q 0.1 mmDeposits l~oise~ Emiss-~ns Fuel Lift (10 = clean) EOT* INCR. EOT* Ilicr.
__ . _ _ _ _ sa,e 36 8.0 ~3.~ 3.0 577 406 l3 ~9 ~.~ 81.3 2.~ 282 51 * Value at end oE test; tlle increa.se (Incr.) showll is in comparisoll to the value at start of test.

'rhe results presented in Table II show tllat there were less cokin-3 deposits (higller air flow rate and ~ewer 3eposits), less engirle noise and less hydrocarbon e.nissions witll Fuel B, the fuel oE the inve-ltion, as colnL)ared to the Base Fuel.
EXAMPLE III
A test blend was prepared ~rom the base ~uel of Example I (Fuel C). Fuel C contained a combination o~
(i) 41 PTB (0.117 grams per liter) of HI'rEC E-644, a product of Edwin Cooper, Xnc., helieve~ to be a hydro-carbyl succinimide-succinarllide made by reacting two moles of a polyisobutenyl succinic anhydride ~PIBSA) witll one mole of a polyethylene a,nine mixture having an average composition corresponding to tetraethylelle pentamine, (ii) 14 PTB (0.04 grams per liter) of a hydrocarbyl amine available commercially ~rom Rohlil and ll~as Company under the trade mark Primene 81~, and .

1~4~3'3 (iii~ 1.7 Plrl3 (0.00~8fi grams per liter) o~ Ethyl# Metal Deactivator, a product of r~tllyl Corporation, the active i.n-3rediellt ol~ which is N~N~-di!,alicylidelle-1~2-dialnirlo-prvp.llle.
The test engine was operated ullde the same con-ditions as those oE ~xarnple I. The most signi~icallt test results are given in Tal~le III, in wllicll air ~low is exl~ressed as cc/min and hydrocarbon emissions as ppm.

T B 1, E I I I
Air Flow Pintle Obturator Hydrocarbon @ 0.1 mm Deposits Noise, DB Emissions Fuel Lift (10 = clean) EOT* INCR EO'r* Incr Base 36 8.0 83.8 3.0 577 406 C 40 8.5 83.2 3.0 513 278 * Value at end of test the increase (Incr.) showll is in comparison to the value at start oE test.

The results presented in Table III show that there were less coking 3eposits (higher air Elow rate and Eewer deposits), less engine noise and less I-ydlocarbon emissions ~ith Fuel C, the ~uel oE the invelltion, as compared to the ~ase Fuel.

# trade mark

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Distillate fuel for indirect injection, compression ignition engines, containing the combination of (a) an organic nitrate ignition accelerator, (b) a hydrocarbyl amine having from 3 to 60 carbons and from one to 10 nitrogens and (c) N,N'-disalicylidene-1,2-diaminopropane, said combination being present in an amount sufficient to minimize coking in the nozzles of indirect injection, compression ignition engines operated on such fuel.

2. The fuel of claim 1, wherein said ignition accelerator is a mixture of octyl nitrates.

3. An additive fluid concentrate for use in distillate fuels, containing the combination of claim 1 or 2.

4 . A method of inhibiting coking on the injector nozzles of indirect injection, compression ignition engines, comprising:
supplying the engine with a distillate fuel containing the combination of claim 1 or 2 and being present in an amount sufficient to minimize such coking in the engine operated on such fuel.