US3445205A - Fuel oil composition having improved low temperature properties - Google Patents

Description

United States Patent 3 445,205 FUEL OIL COMPOSITION HAVING INIPROVED LOW TEMPERATURE PROPERTIES Seymour H. Pafinkin, Chicago, 111., James H. Kirk, Dyer,

Ind., and William L. Steinhotf, South Holland, III., assignors to Sinclair Research Inc., New York, N.Y., a corporation of'Delaware No Drawing. Filed Sept. 25, 1964, Ser. No. 399,334 Int. Cl. C101 1/18 US. C]. 44-62 3 Claims ABSTRACT OF THE DISCLOSURE A fuel composition having improved low temperature properties is prepared by incorporating into a petroleum distillate fuel boiling having the gasoline range minor amounts of an acrylic acid ester polymer pour depressor and a petroleum microcrystalline wax having a melting point up to about 145 F. and derived from a Mid-Continent base crude oil. The fuel compositions of this invention have reduced pour point and improved low temperature pumpability.

This invention relates to distillate fuel oil compositions having improved pour point and pumpability characteristics at low temperatures. More particularly, the present invention is directed to haze-free distillate mineral fuel oils boiling above the gasoline range containing in combination small amounts of an acrylic acid ester polymer pour depressor and certan microcrystalline waxes derived from mixed base crude oils, often called Mid-Continent crudes.

In order to meet pour point specifications for petroleum distillate fuel oils such as heating oils, diesel fuels and the like it is frequently necessary to incorporate a pour depressor. Many materials are known pour depressors and among these a highly effective class is represented by a group of synthetic resins derived by the polymerization of esters of acrylic acid, including methacrylic esters. It is also known in the prior art that the effect of these acrylic acid ester polymer pour depressors can be aided or assisted by incorporating along with them a small amount of certain microcrystalline waxes. See, for instance US. Patent No. 2,917,375 to Charles N. Hudson wherein is disclosed that microcrystalline waxes derived from paraffinic base oils in conjunction with acrylate polymers are good pour depressants in fuel oils and eliminate hazy formation in the oils. Also demonstrated by the patentee is the fact that microcrystalline waxes obtained from mixed base crudes, on the other hand, when added to the same fuel oils in combination with the acrylate polymers caused the fuel to become hazy at moderate temperatures such as 40 F.

We have now discovered that certain microcrystalline waxes obtained from mixed base or Mid-Continent crude oils, are excellent pour depressant aids and pumpability aids for distillate fuels containing an acrylate pour depressor. In addition the use of the microcrystalline Waxes of the invention does not cause an objectionable haze at reduced temperatures.

The microcrystalline waxes of the present invention are, as aforementioned, derived from mixed or Mid-Continent crude oils, and are characterized by a melting point of about 145 F. maximum, preferably below about 100 F. The microcrystalline waxes can be obtained from Mid- Continent petrolatums by eliminating the high melt portion of the petrolatums. For example, the microcrystalline waxes of the invention can be produced by partial crys tallization of the parent petrolatum, as for instance, by dissolving one part of the Mid-Continent microcrystalline wax into five (5) parts of hot 300 to 400 F. naphtha and collecting the high melting precipitate formed at room 3,445,205 Patented May 20, 1 969 temperature. The resulting solution is then solvent stripped to obtain the desired low melting microcrystalline wax.

Similarly, the microcrystalline waxes of the invention can be obtained by conventional solvent deoiling wherein petrolatum is dissolved in methyl ethyl ketone or mixtures of methyl ethyl ketone and toluene or similar solvent systems and the high melt wax precipitate at reduced temperatures. The portion of petrolatum which is soluble in the solvent at the temperature of crystallization is generally known as foots oil and is predominantly microcrystalline wax. Depending on the solvent deoiling conditions employed a single deoiling or a succession of solvent deoilings of the foots oil produced in each step may be used to obtain the microcrystalline wax of the invention.

The acrylic acid ester resin pour depressors to be used in the instant invention are known materials and include those available commercially as the Acryloids such as Acryloid 150 (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 (a 40% by weight concentrate of acrylate in a hydrocarbon solvent having an API gravity of about 24.0 and a viscosity at 210 F. of about 3577 SUS). These resins are oil-soluble and include, for instance polymerized esters of alpha-methacrylic acid or acrylic acid and monohydric aliphatic saturated alcohols. The alcohols employed are generally those having at least about 8 carbon atoms on the average and preferably about 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 often 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 hydrocarbon solvent. These concentrates normally have API gravities of about 23 to 28, and a viscosity at 210 F. of about 2500 to 4000 SUS.

Improved pour point and pumpability of fuels at very low temperatures; e.g. from the cloud point of a fuel, which may be as high as +15 F. or higher, to 15 F. or lower, can be obtained by incorporating in the fuel small effective amounts, for instance at least about 0.001 volume percent, often about 0.003 volume percent to 0.1 volume percent .(dry basis), preferably about 0.01 to 0.05 volume percent, of the acrylic type pour depressor, and at least about 0.1 volume percent up'to about 1 volume percent, preferably about 0.2 to 0.5 volume percent, of the microcrystalline wax. Higher concentrations of either component can be used, but they are less desirable from an economic viewpoint and in most cases excellent pour depression and pumpability are obtained within the above limits. The best additive combination may differ from fuel to fuel since susceptibility to the additives may vary with fuel composition. 7

Compositions of the present invention can be produced by incorporating the microcrystalline wax in the mineral oil 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 acrylate pour depressor are highly soluble in mineral oils generally. Special conditions of temperature and pressure need not be observed in effecting solution of the additives in the oil. To form a solution of the acrylate pour depressor and the wax in the absence of the distillate fuel, it may be desirable to heat them to an elevated temperature, e.g. to about F., to effect solution.

The hydrocarbon fuel oils which are improved in accordance with this invention are the normally liquid petroleum distillates boiling primarily above the gasoline range and include, for example, diesel fuels, heating oils, etc. These oils are usually petroleum middle distillates, which generally boil primarily in the range of about 250 to 750 F., and commonly have relatively high pour points, for instance, at least at F. or higher. The oils can be in their relatively crude state or they can be treated in accordance with well-known commercial methods such as acid or caustic treatment, solvent refining, hydrotreating, etc. The fuel oils can contain straight run distillate fuel oils, catalytically or thermally cracked fuel oils or mixtures of straight run fuel oils, naphthas and the like with cracked distillate stocks. The cracked materials will frequently be about to 70 volue percent of the fuel.

The following examples are included to further illustrate the present invention.

Example I The wax cake of Example I, 88 SUS at 210 F., 32 cone penetration at 77 F. was deoiled as in Example I employing a solvent to wax cake ratio of 3 to 1 and a temperature of 4045 F. to provide after filtration a second pass wax (85%) and foots oil filtrate (15%). The foots oil was designated CFO-2N.

Example III The wax of Example II, 17 cone penetration at 77 F., was deoiled as in Examples I and II but employing a 45- 50 F. crystallization temperature to produce after filtration a third pass wax (90% 45 cone penetration at 110 F., and foots oil filtrate (10%). The foots oil was designated CF O-3N.

Example IV A 100 gram portion of a Mid-Continent petrolatum having an API gravity of 30.9 and a cone penetration at 77 F. of 61.0 was dissolved in 500 grams of naphtha by heating to 140-145 F. The solution was permitted to cool to 77 F. During the cooling the cloud point was determined to be 113.5 F. When the wax slurry was at the dewaxing temperature, a by weight portion of Hyflo Super Cel (diatomaceous earth) was added to improve filterability and the slurry filtered at the dewaxing temperature on a Buchner funnel. The resulting microcrystalline wax was designated ECDH.

The inspections of the foots oil microcrystalline waxes CFO-IN, CFO-2N, CFO-3N and the microcrystalline wax ECDH prepared in Examples I to IV above are summarized in Table I below. An inspection of a Mid-Continent petroleum used for purposes of comparison in Examples to follow is also included as are other waxes identified in Table I.

4 Example V Samples of No. 2 fuel oils from different sources containing small concentrations of either Acryloid 763 alone, the microcrystalline waxes identified in Table I above as CFO-1N, CFO-2N and CFO-3N and a combination of both Acryloid 763 and the waxes were made up and the pour points, ASTM (D-97), of the samples determined. The No. 2 fuels utilized had the following inspections:

Fuel Oil A Fuel 011 B Composition:

Water White Distillate 15 Gas Oil 55 Light Cycle Oil 30 30 Kerosene 5 Laboratory Tests:

Gravity, API-. 33. 9 34. 6 Flas F. 150 136 Viscosity at 100 F., 0.5... 2. 813 2. 548 Cloud Point, F +2 +4 Pour Point, F- 5 5 Olefins, FIA, percent... 0.2 0.2 Aromatics, FIA, percent 30.1 33. 2 Suliur, percent 0. 34 0. 39 Bromine Number 4. 0 7. 7 Distillation:

IBP, F 305 380 380 406 552 514 584 594 618 632 98 98 The pour point results are shown in Table II below:

TABLE II Additive, Vol. Fuel Oil A Fuel 011 B percent Foots 0 Acryloid-763 1 CFO-1N 21284 21377 21315 21481 Foots Oil CFO-2N 1 A 40% concentrate of the acryloid in hydrocarbon solvent.

The data of Table II demonstrate that the microcrystalline wax of the invention is an effective pour depressor aid in acrylate-containing fuels.

TABLEL-MIC R0 C RYSIALLINE WAXEINSPE CTIONS CFO-1N CFO-2N CFO-3N CFO-0N 1 CFO-OB I CFO-2 a ECDH Petrolatum A Melting Point, F 100 l00 100 100 161 Congealing Point, F..- 83 88 106 88 118 Cone Penetration at 77 F 223 248 207 61 Gravity, I 30 31. 3 32. 8 30. 2 31. 9 Flash 600 575 545 588 590 ire, e50 645 e25 640 Percent 9. 8 8. 1 3. 6 8. 6 7. 4 Viscosity-at 210 F., SUS 113 101. 4 88. 5 107. 2 98, 0

l A mierowax combination of at least 2 of CFO-1N, GFO2N and CFO-3N.

1 A mlcrowax combination of a series of CFO-2N waxes.

' A second pass foots oil microcrystalline wax obtained according to Examples I and II but employing a dliierent starting Mid- Continent petrolatum.

Example VI The following tests demonstrate the resistance to solids formation, i.e. suspended (haze) or settled wax precipitates, exhibited by the compositions of the invention using the Mid-Continent microcrystalline wax of the invention, i.e. microcrystalline waxes CFO-1N, CFO2N, CFO-3N and ECDH of Examples I through IV, in comparison to a Mid-Continent micro'crystalline wax having a M.P. of 161 F. (Wax A).

The tests comprised storing samples of a depressed No. 2 fuel, i.e. containing the combination of additives, in 4 oz. bottles under conditions of room temperatures of 40 F. After 48 hours the samples were inspected for visual haze, wax flocullants or wax precipitate. The concentrations of the additives and the results of the tests are shown in Table 1H.

at room temperature was placed in a 275-gallon fuel storage tank in a cold room, maintained at a constant temperature of either +10 F., -8 F. or 15' F., and the tank was manifolded to a home burner pump located in an adjacent warm room at normal temperatures. Immediately preceding the pump in the warm room was a filter. The test fuel was routed from the pump under a pressure of 100 p.s.i. through a total gallonage meter to a 75 g.p.h. nozzle, thence to discard. The pump was operated on a -minutes on, IO-minutes off basis, starting immediately after charging the fuel to the tank. Pumpability failure was taken as the point when fuel ceased to be pumped over a time period of at least minutes, and the percentage of initial fuel oil charge removed from the tank was determined. The results of the tests, the concentration of additives utilized and the TABLE III.-PBECIPITATE FORMATION IN FUELS CONTAININ G MIC RO- CRYSIALLINE WAXES [Bottle Storage Test at F.]

Inspection Alter +40 F. Storage 48 Hours Wax Percent Pour Percent Visual Wax Ppt., Microcrystalllne Wax Vol. Depressant Vol. Haze F100 Inches 0. 1 Acrylold 763. 0.02 W8 A 0.2 ---.do 0.02 M 0. 3 0. 02 34 0. 4 0. 02 t 3'8? 3 0. ECDH 0. 3 0. 02 0 0. 4 0. 02 0 0. 1 0. 02 0 CFO-1N 0. 2 0. 02 0 0.3 0. 02 0 0. l 0. 02 0 CF O2N. 0. 2 0. 02 0 0. 3 0. 02 0 0. 1 0. 02 0 C F O-3N 0 2 0. 02 0 0.3 0. 02 0 Example VII No. 2 fuel oil compositions containing small amounts pour and cloud points of the compositions are shown in Table IV.

TABLE IV.-THE EFFECT OF ADDITIVES ON PUMPABILITY FULL-SCALE TEST Additives Vol. Percent Acryloid 763 Percent Pumped our Cloud/ Depressant Vol. Wax Pour 0 F. -5 F. -10 F. -15 F.

Fuel Oi1A +210 100 83 36 27 0. 02 0.2 E 0. 02 0.2 o 0. 02 0.2 o 0.02 0.2 o 0.02 0.2 o 0. 02 0.2 o 0. 02 0.1 o 0. 02 0.2 o 0.01 0.2 CF 0.00 0.2 o o. 02 0.4 o

0. 02 0.2 E 0. 02 0.2 o o. 02 0.2 o 0. 02 0.2 c 0. 02 0.2 o 0. 02 0.2 o 0.01 0.2 c 0.00 0.2 o 0. 02 0.4 o

of either Acryloid 763, or the microcrystalline waxes identified in Examples I to IV and Table I above and samples containing a combination of the two additives were subjected to a pumpability test over a temperature range of 0 to 15 F. For comparison the neat fuel was also tested. The No. 2 fuels employed are those identified in Example IV above.

The pumpability test employed comprises the followmg' The data of Table IV show that not only is the microcrystalline wax of the invention an excellent pour depressor aid when used in combination with an acrylic acid ester polymer but it is also an excellent pumpability aid over low temperature ranges.

It is claimed:

1. A fuel composition consisting essentially of a petroleum distillate fuel boiling above the gasoline range having incorporated therein about 0.001 to 0.1 volume 4 0 gallons of the fuel composition tested while still percent of a viscous, oil-soluble acrylic acid ester poly- 8 mer pour depressor and about 0.1 to 1 volume percent References Cited of a petroleum microcrystalline wax having a melting point of up to about 145 F. and derived from a Mid- UNITED STATES PATENTS Continent base crude oil, said amounts being sulficient 17,375 12/1959 Hudson 4462 to provide said fuel with a reduced pour point and im- 5 proved pumpability. DANIEL E. WYMAN, Primary Examiner.

2. The composition of claim 1 wherein the melting point 0 the microcrystalline wax is below about 100 F. SMITH Assistant Exammer' 3. e composition of claim 2 wherein the amount of us CL XR' said microcrystalline wax is about 0.2 volume percent up 10 to 0.5 volume percent and the amount of acrylic acid 80 ester polymer pour depressor is about 0.003 to 0.05

volume percent.