US3751236A - Sludge dispersant compositions - Google Patents

Abstract

Sludges and fine particulate matter which normally accumulate in petroleum distillate products are maintained in a suspended state by the addition of a dispersant which comprises an amine neutralized condensation product of a partial fatty acidphosphoric acid ester of a polyoxyethylene or polyoxypropylene ether of a polyol having four to six carbon atoms. Compositions having from one to eight polyoxyalkylene groups, one to four fatty acid ester groups, and one to two phosphoric acid groups per mol of polyol are particularly useful as ashless fuel oil sludge dispersants.

Description

United States Patent [191 Adams l l SLUDGE DISPERSANT COMPOSITIONS [75] Inventor: Alan D. Adams, Newark, Del.

[73] Assignce: Atlas Chemical Industries, Inc.,

Wilmington, Del.

22 Filed: June 10, 1971 '21 Appl.No.: 151,964

[52] U.S. Cl 44/66, 44/DlG. 4, 44/72 [51] Int. Cl ..Cl0l1/26 [58] Field of Search 44/66, DIG. 4, 72

[ 1 Aug. 7, 1973 Primary ExaminerDaniel E. Wyman Assistant ExaminerMrs. Y. H. Smith Att0rneyl(enneth E. Mulford and Roger R. Horton [57] ABSTRACT Sludges and fine particulate matter which normally accumulate in petroleum distillate products are main-' tained in a suspended state by the addition of a dispersant which comprises an amine neutralized condensation product of a partial fatty acid-phosphoric acid ester of a polyoxyethylene or polyoxypropylene ether of a polyol having four to six carbon atoms. Compositions having from one to eight polyoxyalkylene groups, one to four fatty acid ester groups, and one to two phosphoric acid groups per mol of polyol are particularly useful as ashless fuel oil sludge dispersants.

7 Claims, No Drawings SLUDGE DISPERSANT COMPOSITIONS This invention relates to distillate fuel oil additive compositions and mixtures containing straight-run fuel oils which if untreated gradually oxidize or otherwise decompose during storage to form insoluble sludge and sediment which are often responsible for the subsequent clogging of fuel lines, filters, and passageways in engines and burner systems through which such fuels pass. When such plugging occurs, the system ceases to operate or reduces operating efficiency to the point where the engine or burner must be shut down for cleaning.

Another problem which arises from storage of fuel oils is the accumulation of moisture from the air which enters the tank and condenses to form an aqueous layer .which if emulsified with the oil may cause rusting and corrosion of fuel lines, engines, nozzles, and other associated equipment.

The deterioration of distillate fuel oils on storage and the subsequent formation of both soluble and insoluble residue has been recognized for sometime, but the mechanism by which these sludges are formed is not clearly understood. It is believed, however, tov be associated with oxidation and the polymerization of free radicals that are thereby formed. lncorporation of antioxidants is not successful in stabilizingthe fuel oil fraction of petroleum distillate as it is in others such as gasolines, greases, lubricating oils, or in rubber products.

Additives such as esterified ethanol ammonium phosphate salts described in US. Pat. Nos. 2,574,954 3,574,955; tetraalkyl ammonium salts of an alkyl polyalkyleneoxy ester of phosphoric acid such as described in US. Pat. No. 2,904,416 or aliphatic ammonium salts of dialkyl orthophosphoric acid such as described in US. Pat. No. 2,905,541 have not proven to be completely satisfactory for economic reasons.

It is the primaryobject of the invention to provide a process for treating fuel oils such that sludge forming materials are maintained in suspension.

It is also the object of the present invention to provide an improved phosphate additive-petroleum distillate composition which when incorporated at high dilution with petroleum distillate fuel oils overcomes all the difficulties enumerated above.

Another object is to provide a fuel oil composition which is free from sludge over long periods of time.

These objectives are attained by the surfactants of the invention which act to stabilize any sludge forming ingredients and to prevent their agglomeration. Therefore, such sediments are held in a finely divided state and are capable of passing through filter screens into the combustion chamber. A significant advantage offered by the additives of this invention is that they burn clean and leave no ash deposit within the burner.

The sludge dispersant and stabilizing compositions of this invention comprise a series of amine neutralized condensation products of: a partial fatty acid ester of a polyoxyethylene or polyoxypropylene ether of a polyol having four to six carbon atoms andhaving one hydroxyl group per primary, secondary, or tertiary carbon atom; with a phosphoric acid or a phosphoric acid anhydride (phosphorous pentoxide P having from 69 100 percent by weight of phosphorous pentoxide equivalent, wherein said ether contains from 1 up to about and preferably four to six oxyalkylene groups per mol of polyol, said partial ester contains from one to four acylate radicals per mol, and said condensation product contains from two to four mols of said partial ester per mol of phosphorous pentoxide equivalent. These compositions and their salts are most effective as sludge dispersants in fuel oils in concentrations of at least 0.0016 grams per mls. up to 0.02 grams per 100 mls. and higher.

The amine salts of the compositions of this invention are formulated in a sequence of reaction steps, the first of which comprises condensing a polyol having four to six carbon atoms and in most cases one hydroxyl group per primary, secondary, or tertiary carbon atom with an oxyalkylene compound such as ethylene or propylene oxide. Such compounds as erythritol, pentaerythritol, adonitol, and hexitol are useful polyols. Sorbitol and mannitol are preferred hexitols.

These polyols can be condensed with up to 15 mols and preferably from one to eight mols of ethylene oxide or propylene oxide by any of many well-known techniques. Usually, however, condensations are performed in an autoclave under pressure. The condensation of alkylene oxide with a hydroxyl group produces at a hydroxyl site a B-hydroxyethyl ether linkage. As is well recognized, the condensation of several mols of an alkylene oxide with a polyol produces etherified polyols containing the same number of hydroxyl groups as the polyol with oxyalkylene groups more or less randomly distributed in the molecule.'lt is customary in the art to designate such mixtures as the numberof oxyalkylene groups condensed per mol of polyol and such terminology will be adopted hereafter. Thus, for example, the condensation of four mols of propylene oxide with one mol of sorbitol will be called Polyoxypropylene(4)Sorbitol or- POP(4)Sorbitol. Likewise, a condensation product formed by condensing l5 mols of ethylene oxide with adonitol will be called POE( l5)Adonitol.

In the next synthesis step, a polyol-polyether composition of the type described previously including readily available intermediates such as those listed in Table l is further condensed with from one to four mols of a saturated or unsaturated fatty acid having from 10 to 20 carbon atoms such that at least one hydroxyl remains unreacted. Such acids as capric, lauric, myristic, palmitic, stearic, and arachidic are preferred saturated acids; while palmitoleic, oleic, ricinoleic, linoleic, and

other acids within the range which are easily obtained from natural products are most useful. Readily available odd-numbered acids such as undecylic, tridecylic, for example, are to be included. Portions of each of the two compounds are mixed together and reacted at temperatures in excess of 200C.

In this reaction, the acyl group attacks a hydroxyl group either on the polyol molecule or at the end of a hydroxy ether side chain to form an ester of the fatty acid. A condensation product wherein 3 mols of. oleic acid is condensed with Polyoxypropylene(4)Sorbitol is designated as POP(4)Sorbitol Trioleate.

ln the next synthesis step, the 'alkoxylated polyol ester obtained either as described above including readily available intermediates such as those listed in Table ll are further reacted with phosphoric acid, polyphosphoric acid, or their anhydride (phosphorous pentoxide P 0 to form a condensate containing on the average one to two mols of phosphoric acid equivalent per mol of alkoxylated polyol ester. If one mol of the polyethoxylated polyol ester is reacted with one mol of phosphoric-oxygen compound equivalent to.

one mol of phosphoric acid, the term monophosphate is applied; however, if two mols of the polyol ester is condensed with three mols of the orthophosphoric acid equivalent, the term sesqui or 1.5 phosphate is employed. The acid links with the alkoxylated polyol ester through available hydroxyl groups either on the polyol molecule or on the hydroxy ether side chain. When phosphoric acid, per se, is used, water is split out in the condensation. However, if the anhydride such as phosphorus pentoxide is used, no water is eliminated. A most expeditous route for forming these phosphate derivatives is to add phosphorus pentoxide either as a dry powder or slurried in an inert organic liquid to a heated fatty acid ester. Any residue which is insoluble in the mix can be filtered from the reaction product prior to the removal of the organic liquid. A condensation product formed by condensing one mol of palmitic acid with one mol of POE(1) Erythritol followed by condensation of one mol of phosphoric acid equivalent is termed POE( 1 )Erythritol Monopalmitate- 1 Phosphate.

The above phosphates can then be neutralized by reaction. with strong inorganic or organic bases. Such salts are formed by mixing with the phosphates low molecular-weight organic primary, secondary, or tertiary amines such as propylamine, isopropylamine, butylamine, ethylamine, methylamine, dimethylamine, diethylamine, diisopropylamine, hydroxyethylamine, monoethanolamine, diethanolamine, trimethylamine, triethylamine, and others to form neutral products. Higher molecular-weight amines are also suitable, but those with up to five carbon atoms per organic group are preferred. The amount of amine to be added varies from composition to composition and depends upon the structural complexity of the phosphate. A suitable method for determining the acid content of the composition is to determine the neutralization equivalent with such base as sodium hydroxide prior to the addition of amine. A composition resulting from neutralization with isopropylamine (IPA) and the sesquiphosphate of mannitol condensed with five mols of ethylene oxide and 3 mols of stearic acid would be designated IPA- POE(5 )Mannitol Tristearate-1.5 Phosphate.

IPAPOP(4)SORBITOL DIOLEATE-l.5 PHOSPHATE One thousand two hundred seventy three parts by weight of Polyoxypropylene(4)Sorbitol made in an autoclave by the condensation of propylene oxide with sorbitol at a mol ratio of4 to 1 is mixed with 1988 parts by weight of a commercial grade of oleic acid (Acintol- FA No. 2) produced by the Arizona Chemical Company and heated under a blanket of nitrogen with stirring over a period of 4 hours at a temperature of 250C. 1440 parts by weight of this composition is heated to 105 l C. under a nitrogen blanket and mixed with 115 parts by weight P 0 slurried in toluene. Since a small portion of P,O does not react initially, the liquid product requires additional quantities of P 0 to be added to bring the phosphorus content up to 4.16 percent. The ammonium salt of this composition is formed by mixing 342.8 parts of the phosphate with 31.2 parts of isopropylamine and heated to 87 99C. over a period of 1.25 hours to yield a product containing 1.96 percent nitrogen.

IPA-POE(4)SORBITOL TRIOLEATE- l .5 PHOSPHATE One thousand one hundred eighty four parts by 5 weight of Polyoxypropylene(4)Sorbitol and 2272 parts by weight oleic acid were heated together under a nitrogen blanket to 250C. for a period of 11 hours to produce 31 14 parts of POP(4)Sorbitol Trioleate. 1452 parts of this composition was mixed with l 10 parts by weight of P 0 slurried with 100 parts toluene over a period of 1 hour, then heated to 100 315C. with stirring for a total of 2.5 hours. The mix was filtered to remove residue and vacuum stripped at 0.1 mm. Hg. at 100 105C. 311 parts by weight of this composition is mixed with 23 parts by weight of isopropylamine and heated to C. with stirring until homogenous. The product obtained contains 3.02 percent phosphorus and 1.43 percent nitrogen.

In Table 111 are listed several other compositions which were made according to procedures similar to that of Examples 1 and 2.

EXAMPLE 1 Because the preferred salt additives described above are thick and viscous at room temperatures, concentrated fluids are made by incorporating them with minimum quantities of fuel oil, kerosene, or other petroleum distillate products to form fluid which can be easily pumped and metered. These fluids are then added to distillate fuels to form very dilute concentrations of at least 0.0016 grams per 100 mls, and up to about 0.02 grams per 100 mls. (0.8 grams per gallon) (1 oz. per barrel). A stock solution of 5 grams/ mls. (5% w/v) in No. 2 fuel oil is used as the carrier in the following tests.

EXAMPLE 2 A petroleum distillate fuel oil stabilized against the deposition of sludge upon storage is prepared by adding 3 mls. of the stock solution of Example 1 per liter of No. 2 fuel oil to yield a composition containing 0.015 gms. of the mixed monoethanol amine salt per mls. of oil. Higher and lower concentrations from at least 0.001 gms. up to about 0.02 gms. per 100 mls. (0.8 gms./gallon) (1 oz./barrel) are made by diluting stock solutions or by adding the mixed salt directly to the fuel oil to be stabilized.

PUMPING TEST The effectiveness of the additives is demonstrated in a test apparatus comprising a reservoir with agitator from which an oil is recycled in series through a water trap, a filter, a pump, and a standard nozzle return outlet. The equipment is also provided with a pressure gauge and means for controlling the pressure in the line. In this apparatus two-gallon portions of untreated No. 2 fuel oil or kerosene are treated with sufficient quantities of the dispersant composition stock solution of Example 1 to yield the concentrations indicated in Table I. To the treated oil are then added synthetic sludge designated K-801 provided by the Baltimore Paint and Color Company to adjust the concentration of theoil mix to 0.06 mls. per 99.14 mls. and 66 mls. of a synthetic rust slurry prepared by separately dissolving 20.32 gms. of ferric chloride-6 hydrate and 16.04 gms. of ferrous chloride-4 hydrate in 600 ml. portions of tap water, mixing these together and adding to this solution 200 mls. of awater solution containing 15.5 gms. of sodium hydroxide, diluting to 2,000 mls. with water and ageing for 1 week. The contents of the reservoir are agitated for 2 minutes during the addition of the sludge and rust slurry.

A felt filter having a permeability for No. 2 fuel oil of 530-:30 mls. per minute under a hydrostatic head of 18 inches is placed in the filter holder. The test is run for a total period of 3 hours with the circulating pump pulling the oil from the reservoir through the filter and back to the reservoir. At the end of 1 hour of circulation and also after 2 hours, the flow through the filter is measured at a hydrostatic head pressure of 18 inches and is compared with the initial flow of clean No. 2 fuel oil. Each time, an additional charge of additive, sludge, and rust slurry equivalent to that used originally is placed in the reservoir as described. After one additional hour of circulation, the flow is again measured at the l8-inch hydrostatic head pressure. The results are expressed in Table l for the several concentrations tested, as percentages of the flow rate of clean No. 2 fuel oil. The results in the table are compared with fuel oil having no additive and equal concentrations of additives available commercially.

TEST FOR EMULSIFICATION PROPERTIES 1 It is critical in some instances that a sludge dispersant be ineffective in the formation of oil-in-water or waterity of the oil layer was determined'by removing the top 20 ml. portion and measuring its light transmission with a Beckman Model B spectrophotometer, using additive fuel as the standard (100% T) and'a wave length of 420 5 mu. These results are recorded in Table III and indicate that the additives of this invention do not appreciably emulsify water and at the same time give improved sludge dispersancy.

10 TABLE 1 Available Intermediates Sorbitol Derivatives A POE(2)Sorbitol B POE(3)Sorbitol C POE(4)Sorbitol D POE(6)Sorbitol E POE(8)Sorbit0l F POP( l )Sorbitol G POP(3)Sorbitol I H POP(6)Sorbitol l POP( 8 )Sorbitol Mannitol Derivatives J POP(6)Mannitol TABLE ll Available Intermediates .Esters of POE and POP Mannitol and Sorbitol in-oil emulsions. To demonstrate the desirable water A pOE(6)Mannito| Dioleate separation properties, the distillate fuel oils containing 3 PoE(3)So -bit Monolaumte the above-described additive is tested for water toler- C pog s bi Monolaurate ance according to U.S. Federal Test Method Standard D p0E(6)S -bim| Dil t No. 791a, Method 3201.5 entitled Emulsion and E PQE( )s -bim| T il rar Method 3251.7 entitled Interaction of Water and Air- F POE(6)SOfbitOI T tr l rate craft Fuels as described in Lubricants, Liquid Fuels G POE(6)Sm-biml Tri leate and Related Methods of Testing. The'following test is a H POE(6)S i-bit l Tetraoleate modification and combination of these tests and in- I POE(3)Sorbitol Monopalmitate volves vigorous agitation of 150 mls. of the oil contain- J POE(6)Sorbit0l Monopalmitate ing the additive with mls. of water at 1,500 R.P.M. 40 K POE(6)Sorbitol Dipalmitate for 5 minutes at room temperature and thereafter al- L POE(6)Sorbitol Tripalmitate lowing the emulsion to remain undisturbed for a period M POE(6)Sorbitol Tetrapalmitate of 24 hours. After periods of l, 2, 5, and 24.hours, the N POP(6)Sorbitol Trioleate water-fuel interface was observed and rated. The clar- O POP(6)Mannitol Dioleate H r 5 r M... W. em... .2... .7

Emulsification test Interface rating Separation, mls. Light transmissio; Concen- Pump after- 2 H1O aiter percent T aftertration, test, gms./l00 percent 1 2 24 1 2 5 2i 1 2 5 24 Example Additive mls. flow hr. hr. hr. hr. hr. in. hr. hr. hr. hr. hr. hr.

(:onlrol A Untreated fuel oil #2 0 14 B f 8 852 62 3 3 3 3 4s 48 -18 4s 00 09 98 08 0. 013 0a (onti'ol Barium petroleum sull'onatc 0. 0065 64 .2 2 2 2 I 2- 9 1 f 65 3. 5 5 5 2s 32 32 a5 02 50 9 2 IPA-POE (4)sorhitoldioleate-lj- 1 0.013 86 l phosphate. I 0.0005 77 i 3 [PA-POP(4)s0rbitoltrioloate-L5- i 0.013 03 1 phosphate. 1 0.00325 68 j -l 1P POP(fi) 'l't 101-1 1- a? hosplmm )1 5 5 0 n 15 20 a s1 97 100 8(1)? 04 5 A 97 g g g 1 0. 0065 15 1 5 5 5 5 40 42, 53 +4 91 ea 5 7 0. 003-25 80 rllA-POE (4) SOIlJllOl trioleate-li 0.013 76 l phosphate. l 0. 0065 67 i 7 IPA-POE (4) soihitol dioleato-l- 0.013 80 phosphate. 0.0065 71 l Final flow X 100 I Pol-"om now Initial flow Rating: i=(loan or clear: 1h=A few small bubbles covering 50% of interface and no shreds, lace. or film at interface; 2=Shred of lace and/or film} 3=Loos0 lace and/or light scum; 4=Tight lace and/or heavy scum; 5=Tight lace and/0r heavy scum and 75 ml. tight emulsion.

What is claimed is:

l. A fuel oil sludge dispersant which comprises a petroleum distillate having incorporated therein an organic amine salt of a condensation product formed by reacting a partial fatty acid ester of a polyalkoxy ether of a polyol having four to six carbon atoms and one by droxyl group per primary, secondary, or tertiary carbon atom with from one to two molar equivalents of phosphoric acid either as the free acid or phosphorous pentoxide, said fatty acid ester being a condensation product of a mol of polyalkoxy ether having I l polyoxy-ethylene or polyoxypropylene units with from one to four mols of fatty acid having 20 carbon atoms such that at least one hydroxyl group remains unreacted, and wherein said organic amine is a primary, secondary, or tertiary alkyl or hydroxy alkyl monoamine.

2. A composition of claim 1 wherein said polyol is selected from the group consisting of mannitol and sorbitol, and said fatty acid is selected from the group consisting of oleic, lauric, and palmitic acid, and wherein said organic amine has up to 5 carbon atoms per organic alkyl group.

3. A composition of claim 2 wherein said polyol is sorbitol having four to six polyoxyethylene or polyoxypropylene groups per mol, from two to three oleic acid acyl groups per mol, and said organic amine is iso propylamine.

4. A dispersant of claim 1 having an organic amine salt of said condensation product in concentrations of at least 5 grams per 100 mls.

5. A petroleum distillate fuel oil stabilized against the deposition of sludge having incorporated therein from 0.001 to 0.02 grams per mls. of said fuel of a dispersant which comprises an organic amine salt of a condensation product formed by reacting a partial fatty acid ester of a polyalkoxy ether of a polyol having four to six carbon atoms and one hydroxyl group per primary, secondary, or tertiary carbon atom with from one to two molar equivalents of a phosphoric acid either as a free acid or phosphorous pentoxide, said fatty acid ester being a condensation product of a mol of polyalkoxy ether having 1 15 polyoxyethylene or polyoxypropylene units with from one to four mols of fatty acid having 10 20 carbon atoms such that at least one hydroxyl group remains unreacted, and wherein said organic amine is selected from the group consisting of a primary, secondary, or tertiary alkyl or hydroxy alkyl monoamine.

6. The petroleum distillate fuel oil of claim 5 wherein said polyol is selected from the group consisting of mannitol and sorbitol, said fatty acid is selected from the group consisting of oleic, lauric, and palmitic, and said composition having from one to eight oxyethylene or oxypropylene groups, and wherein said organic amine has up to five carbon atoms per alkyl group.

7. The petroleum distillate fuel oil of claim 6 having from 0.0032 0.15 grams of said amine salt per 100 mls. of said fuel.

Claims (6)

1. 2. A composition of claim 1 wherein said polyol is selected from the group consisting of mannitol and sorbitol, and said fatty acid is selected from the group consisting of oleic, lauric, and palmitic acid, and wherein said organic amine has up to 5 carbon atoms per organic alkyl group.
2. 3. A composition of claim 2 wherein said polyol is sorbitol having four to six polyoxyethylene or polyoxypropylene groups per mol, from two to three oleic acid acyl groups per mol, and said organic amine is isopropylamine.
3. 4. A dispersant of claim 1 having an organic amine salt of said condensation product in concentrations of at least 5 grams per 100 mls.
4. 5. A petroleum distillate fuel oil stabilized against the deposition of sludge having incorporated therein from 0.001 to 0.02 grams per 100 mls. of said fuel of a dispersant which comprises an organic amine salt of a condensation product formed by reacting a partial fatty acid ester of a polyalkoxy ether of a polyol having four to six carbon atoms and one hydroxyl group per primary, secondary, or tertiary carbon atom with from one to two molar equivalents of a phosphoric acid either as a free acid or phosphorous pentoxide, said fatty acid ester being a condensation product of a mol of polyalkoxy ether having 1 - 15 polyoxyethylene or polyoxypropylene units with from one to four mols of fatty acid having 10 - 20 carbon atoms such that at least one hydroxyl group remains unreacted, and wherein said organic amine is selected from the group consisting of a primary, secondary, or tertiary alkyl or hydroxy alkyl monoamine.
5. 6. The petroleum distillate fuel oil of claim 5 wherein said polyol is selected from the group consisting of mannitol and sorbitol, said fatty acid is selected from the group consisting of oleic, lauric, and palmitic, and said composition having from one to eight oxyethylene or oxypropylene groups, and wherein said organic amine has up to five carbon atoms per alkyl group.
6. 7. The petroleum distillate fuel oil of claim 6 having from 0.0032 - 0.15 grams of said amine salt per 100 mls. of said fuel.