US2917375A - Fuel oils - Google Patents

Description

Eg pl n FUEL OILS Charles N. Hudson, Lansing, 111., assignor to Sinclair Refining Company, New York, N.Y., a corporation of Mame No Drawing. Application July 31, 1958 Serial No. 752,201

2 Claims. (CI. 44-62) The present invention relates to new compositions of matter. More particularly the present invention relates to mineral oil compositions containing pour depressors and pour depressor aids which in addition prevent or avoid the formation of suspended or settled solids in the compositions.

In order to meet pour point specifications for mineral oil compositions such as heating oils and diesel fuels, it is frequently necessary to employ an additive known as a pour depressor. Many materials are known pour depressors and among these a highly efiective class is represented by a group of synthetic resins derived by the polymerization of esters of acrylic and methacrylic acids. One disadvantage of polymers of esters of acrylic acids as pour depressors is their high expense. Such disadvantage is generally not shared by other known pour depressors; however, the eifectiveness of the acrylic resins has, in the past, outweighed their expense.

It is also known in the prior art that the eifect of pour depressors can be aided by incorporating in the mineral oil-pour depressor composition a material known in the art as a pour depressor aid. Examples of known pour depressor aids include hydrocarbon waxes, for example amorphous waxes and crystalline waxes such as paraffin waxes, both those derived from petroleum and native parafiin waxes, e.g. ozocerite (see U.S. patent to Martin 2,615,799). While the use of pour depressor aids of the type mentioned is eifective in reducing concentration of pour depressor needed, generally the mineral oil-pour depressor-pour depressor aid composition experiences the formation of solids, i.e. suspended (haze) or settled wax 1 precipitates, when stored for short periods of time, e.g.

in excess of about 24 hours.

Among the undesirable efiects resulting from solids formation in mineral oils of the type described above, the deleterious effects to the free flow of the mineral oils through oil screens and lines, due to the obstructive nature of the solids formed therein, are particularly undesirable. Further, the expense of acrylic type pour depressors limits the quantity which may be incorporated in marginal fuels. At very low concentrations of pour depressor in marginal fuels, known pour depressor aids have not been especially satisfactory in facilitating a lowering of the pour points.

I'have now discovered that paraffin base microcrystalline wax when used in conjunction with acrylic type pour depressor resins in mineral oil compositions, containing marginal oils as well as cracked oils, permits the use of exceedingly low concentrations of pour depressor. I have also discovered that paraflin base microcrystalline wax can be used as a pour depressor aid for acrylic type pour depressors in distillate fuels containing marginal as well as cracked components. The use of such an aid in this manner results in a composition characterized by great stability in storage and superior resistance to solids formation, i.e. suspended (haze) or settled wax precipitates. In accordance with my invention small amounts of microcrystalline waxes derived from parafiin base oils are used as pour depressor aids to obtain the advantages described.

tes Patent The microcrystalline waxes which are used as pour depressor aids in the present invention are commercially available and are derived from paraffin base oils. More particularly a Pennsylvania vacuum still bottoms or reduced crude is treated with propane to precipitate the resins contained therein; after separating the resins, microcrystalline waxes are obtained by employing the conventional methylethyl ketone dewaxing process.

When employing the paraffin base microcrystalline wax pour depressor aids of the present invention in conjunction with acrylic type pour depressors in distillate fuels containing marginal and cracked components, -I have found that concentrations of depressor aid of about 0.2 to 0.4 weight percent are effective with acrylic type pour depressor concentrations of about 0.01 to 0.03 weight percent of commercial concentrates, or concentrations of about 0.003 or 0.004 to 0.02 on a percent basis, to lowerthe pour point. Use of these concentrations advantageously results in distillate fuel compositions with superior resistance to solids formation than known distillate fuel-acrylic type depressor-depressor aid compositions. Concentrations of depressor aid of about 0.2 to 0.4 weight percent permit the use of as low as 0.01 to 0.03 weight percent of commercial concentrates of acrylic resin to effectively lower the pour point of marginal stock-containing compositions.

Marginal stock as used in this specification is intended to indicate petroleum hydrocarbons which may or may not include cracked components, such as straight run gas oils and catalytic or thermal cycle or gas oils for example, generally at least about 10 weight percent and usually not more than about 70 percent and preferably from about 10 to 50 percent gas oil that normally cannot be employed in fuel oils because of their high pour point. Such stocks generally have distillation end points of 600 F. to 675 F. or even to 700 -F. Cracked oils as used in this specification is intended to indicate, for instance, cracked light gas oil, and will generally comprise at least about 10 percent but usually about 10 to 50 percent of the composition.

Heating oils and fuel oils encompassed by the present invention include those distillate fuels having boiling ranges intermediate the boiling range of kerosene and lubricating oils, i.e. about 340 to 700 F., and normally have pour points of about 5 to- 15 F. These include virgin light distillates and catalytically cracked cycle oils and blends of the foregoing. Also, blends of more than two distillate fuels having boiling points within the defined range can be employed.

The acrylic resin pour depressors to be used in the instant invention are known articles of commerce available commercially as Acryloid (a methacrylate ester polymer prepared from cetyl, lauryl and octyl alcohols with a molecular Weight of about 10,000 to 15,000), Acryloid 710 (a methacrylate ester polymer prepared from lauryl and octyl alcohols with a molecular weight of about 10,000 to 20,000), and Acryloid 763 (from Rohm and Haas). These resins are oil-soluble and are partially polymerized esters of alpha-methacrylic acid or acrylic acid and monohydric aliphatic saturated alcohols. The alcohols employed are those having at least 12 carbon atoms on the average and preferably 12 to 24 or more carbon atoms per molecule. Typical pour depressors are polymers of dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, and octadecyl methacrylate. The polymers have molecular weights of about 500 to 20,000. In commercial form, the pour depressors are available as a 40 weight percent concentrate in a high grade solvent. These concentrates normally have APl gravities of about 23 to 28, and a viscosity at 210 F. of about 2500 to 4000 SUS.

Compositions of the present invention can be produced by incorporating the microcrystalline wax in the mineral O l. fraction either before or after the pour depressor is added, or the depressor aid can be added to the pour depressor separately from the oil and then incorporated in the oil as a mixture with the pour depressor; Microcrystalline waxes generally are highly soluble in acrylic type pour depressors and, of course, both the waxes and the pour depressor are highly soluble in mineral oils gen: erally. Special conditions of temperature and pressure need not be observed in eifecting solution of pour depressor and pour depressor aid in the oil; to form a solution of pour depressor and pour depressor aid in the absence of the distillate fuel, it is desirable to heat to an elevated temperature, e.g. to about 125 F. to effect the solution.

The invention will be further described by. the following specific examples.

EXAMPLE I A mineral oil heating fuel was made by blending 6.3 percent of a naphtha having a boiling range of about 300 to 400 F., 19 percent of water white distillate, 34.7 percent of a 675 F. cut point light gas oil and 40 percent of a 675 F. cut point light cycle oil (all quantities are volume percent). The characteristics of the blend are as follows:

Tests:

Gravity, API 33.7 Flash, F 160 Viscosity, centistokes, at 100 F. 3.297 Cloud, F. 12 Pour, F. p Color, NPA 2?- Distillation- IBP 340 5% 408 10% 434 473 30% 504 40% 528 50% 546 60% 566 70% 582 80% 608 90% 618 95% 632 EP 652 Res. 1.0 Cetane No. 45

To samples of this blend, commercial Acryloid 763 was added in varied amounts. Acryloid 763, a 40 weight percent concentrate of acrylate in solution, has an API gravity of about 24.0 and a viscosity at 210 F. of about 3577 SUS. To several of the samples containing the pour depressor, varying concentrations of microcrystalline waxes derives from paraifin base oils were added. Samples of microcrystalline wax derived from a Mid-Continent base oil were added to other samples The oil-pour depressor pour depressor .aid compositions parison purposes.

were tested for cloud and pour points according to the ASTM standard tests. The results are as follows:

MICROCRYSTALLINE WAX, WEIGHT PERCENT Acryloid Paraflin Mid-Oon- Pour, Cloud, Sample 763, Wt. Base tinent F. F.

Percent Base From the above data it is apparent that use of the defined microcrystalline waxes as depressor aids facilitates the lowering of the pour points of distillate fuels containing marginal stocks at low concentrations of acrylic-type pour depressors, While waxes derived from Mid-Continent oils had substantially no eifect at the same concentrations of pour depressor. The compositions were permitted to stand for about four days and were then inspected for haze formation. Each of the samples containing the parafiin base microcrystalline wax was clear While a haze had developed in each of the samples containing the microcrystalline wax derived from Mid- Continent crude oil.

EXAMPLE II The following tests demonstrate the superior resistance to solids formation, i.e. suspended (haze) or settled wax precipitates, exhibited by the compositions of the present invention using paraflin base microcrystalline wax comparison with similar compositions containing microcrystalline wax derived from Mid-Continent crude oil. All oils were essentially clear of suspended precipitate except the oil containing depressor aid A, which was hazy in appearance following storage at a temperature of 40 F.

The tests which formed the basis for the above conclusions were obtained by storing samples of the depressed fuel in gallon bottles under conditions of room temperature as well as cold room temperatures of 40 F. and 10 F. These samples were periodically inspected for solids formation. The distillate fuel used a fuel (Fuel 1) predominantly derived from Mid- Continent crude oil having characteristics shown below in Table III. This fuel was depressed with 0.01 per.- cent Acryloid 763 1 in combination with the following depressor aids:

A. Microcrystalline wax with a melting point of 165 F. and derived from Mid-Continent, i.e. Colorado- Kansas, crude oil.

B. Microcrystalline wax with a melting point of 160 F. and derived from Mid-Continent, i.e. East Texas, crude oil.

C. Microcrystalline wax with a melting point of 123' F. and derived from paraflin base, i.e. Pennsylvania, crude oil.

D. Microcrystalline wax with a melting point 2 of F. and derived from parafiin base, i.e. Pennsylvania, crude oil.

Additional samples of neat fuel were setup for com- The results of the visual inspections are tabulated below in Table I. Since the visual information on the 10 F. samples were indistinguishable a more accurate means of developing information on solids formation was developed and include a quantita- A commercial Acryloid, containing 40 weight percent of acrylate in a hydrocarbon solvent, with an API gravity of about 24.0 and a viscosity at 2l0 F. of about 3577 SUS.

. Meltingppint determined by .test method ASTM D127",49.

tive relationship established by separating and Weighing 70% 535 the wax precipitates. This was done by filtering, with 30% 559 filter aid, a liter of the fuel at the test temperature 90% 588 (+l F.) and Washing the cake free of oil with pen- 95% 607 tane. The cake was extracted with boiling hexane and End Oint 630 the solution filtered. The hexane was evaporated from p 99 5 the filtrate and the Wax residue determined by weighing. Recfveryi Percent The results of these determinations are listed in Table Resldue II. The amount of wax recovered ranged from ml for am 1 is h ilm fi a g fi el made by g g gz zg o o t cen of a nap t a aving a oi ing range 0 a ou 0 .neaflfuel to over 1000 mg/hter for the Sample con 10 400 F., percent of water white distillate, percent of tammg 31d 3' a 641 F. end point light gas 2 oil, and 30 percent of a 557 At 10 F th amount f i l bl formation as F. end point light cycle oil or cracked light gas oil (all quantities are volume percent). shown With data presented in Table II, was considerably Distillation characteristics of the light gas oil: less in the samples containing aids C and D than that P110111 bolllng Pomt, B 452 o w 10% 553 from samples containing a1ds A and B. The 1. 15 20% 5 5 and room temperature storage samples show, with data 285;: 22% presented in Table I, that samples containing aids A 50% 585 and B exhibited the heaviest precipitates While samples 98% containing aids C and D exhibited the lightest precipi- 0% 602 9017 612 tates. In addition the latter samples took longer to form 20 pom 64:1 their respective precipitates. Pour point- 0 Table I PRECIPITATE FORMATION IN POUR DEPRESSED FUEL I Room Temperature Storage 40 F. Storage Depressor Aid 1 Cone, Condition of Percent Appearance Condition of Appearance Condition of Oil After 5 of 1st Insol- Oil After 18 of 1st Insol- Oil After 20 Days Back ubles, Days Days ubles,Days Days At Room Temperature 10 Trace Ppt 20 Trace Ppt. 0.3 3 Medium Ppt 4 Medium Ppt. 0.3 3 Heavy Ppt 4 Do. 0.3 18+ No Ppt... 6 Trace Ppt. 0. 3 18+ do 20 D 1 All fuels except neat contain 0.01% Acryloid 763. Explanation of precipitate observations:

Trace Ppt: Upon hard shaking of bottle small wisp of deposit rises from bottom. Ligit Ppt: Upon light shaking 01' bottle small cloud of deposit rises up from bottom.

Mediurn Ppt: Upon light shaking of bottle cloud of deposit rises filling a of bottle but to insignificant depth. Upon light shaking of Heavy Ppt: Precipitate covers whole bottom bottle large cloud of deposit rolls up filling most of bottle.

Table II LOW TEMPERATURE (10 F.) INSOLUBLE DEVELOPMENT IN POUR DEPRESSED FUEL I Wax Filtered Ofi at 10 F. mtg/1,000 ml.

Original Pour P oint,

Pour Point of 10 F.

Depressor Aid 1 Cone,

Filtrate, F.

Percent 1007 CK 813 277 OK 353 94 OK 100 1 All fuels except neat contain 001% Acryloid 763.

1 The numbers before CK represent the initial values obtained and the numbers following CK" represent values obtained upon checking the initial values.

Table III PHYSICAL CHARACTERISTICS OF A FUEL OIL (RE- FERRED TO AS FUEL 1) FOR POUR DEPRESSOR bout half of bottle.

This application is a continuation-in-part of application Serial No. 457,998, filed September 23, 1954, and now abandoned.

I claim:

1. A distillate fuel composition consisting essentially of a base distillate fuel oil having an end point above about 600 F., about 0.003 to 0.02 Weight percent of a viscous oil-soluble polymerization product of an ester of acrylic acid and a saturated aliphatic alcohol having at least 12 carbon atoms per molecule and about 0.2 to 0.4 Weight percent of a paratfin base microcrystalline Wax; said composition containing at least about 10 weight percent of cracked fuel components.

2. The composition of claim 1 wherein the base fuel oil contains from about 10 to 50 percent of cracked gas oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,177,732 MacLaren Oct. 31, 1939 2,403,267 Davis July 2, 1946 2,615,799 Martin Oct. 28, 1952 2,642,414 Bauer et al. June 16, 1953

Claims (1)

1. A DISTILLATE FUEL COMPOSITION CONSISTING ESSENTIALLY OF A BASE DISTILLATE FUEL OIL HAVING AN END POINT ABOVE ABOUT 600*F., ABOUT 0.003 TO 0.02 WEIGHT PERCENT OF A VISCOUS OIL-SOLUBLE POLYMERIZATION PRODUCT OF AN ESTER OF ACRYLIC ACID AND A SATURATED ALIHATIC ALCOHOL HAVING AT LEAST 12 CARBON ATOMS PER MOLECULE AND ABOUT 0.2 TO 0.4 WEIGHT PERCENT OF A PARAFFIN BASE MICROCRYSTALLINE WAX; SAID COMPOSITION CONTAINING AT LEAST ABOUT 10 WEIGHT PERCENT OF CRACKED FUEL COMPONENTS.