US3403011A - Middle distillate fuel composition - Google Patents

Description

United States Patent 3,403,011 MIDDLE DISTILLATE FUEL COMPOSITION William M. Sweeney, Wappingers Falls, N.Y., assignor to Texaco Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed June 20, 1967, Ser. No. 647,342 8 Claims. (Cl. 44-62) ABSTRACT OF THE DISCLOSURE There is disclosed a novel middle distillate mineral oil composition having a reduced pour point and improved rust-inhibiting properties due to the incorporation in the oil of a minor amount of an additive obtained by reacting an ethylene-propylene-terpolymer with maleic anhydride.

This invention relates to an improved middle distillate mineral oil composition and, more particularly, to middle distillates having improved pour point and rust inhibiting properties. The improvements are realized through the use of an additive comprising the reaction product of an ethylene-propoylene-terpolymer and maleic anhydride.

Heating oils, diesel fuels and viscous hydrocarbon oils employed in cold climates or exposed to low temperatures frequently require the use of an additive to maintain their fluidity or to meet critical low pour point specifieations. Pour depressants reduce their pour point of viscous mineral oil and an effective practical pour depressant is one which will substantiailly reduce the pour point of a viscous oil without imparting any undesirable properties when employed in a low concentration.

Heating oils, diesel fuels and middle distillate oils are transported in pipe lines and tankers and stored for substantial periods of time in storage tanks. The steel structures of these transportation and storage means are highly susceptible to corrosion when in contact with these mineral oil compositions. Indeed, this is so serious a problem that is a common practice to add a corrosion inhibitor to the liquid hydrocarbon oil in order to protect the noted transportation and storage means from corrosion.

It has now been discovered that a substantial reduction in the pour point of viscous hydrocarbon oils and valuable corrosion inhibiting properties can be imparted to such oils through the use of a single additive exhibiting both of these properties. This discovery was unexpected because this combination of properties has generally not been found in a single additive material. The discovery was also surprising because it could not be predicted what properties, if any, would be processed by the reaction product of an ethylene-propylene-terpolymer and maleic anhydride.

This invention is directed to middle distillate mineral oil compositions containing a pour depressant and corrosion-inhibiting amount of the reaction product of an ethylene-propylene-terpolymer and maleic anhydride.

The ethylene-propylene-terpolymer component of the reaction product of this invention consists of polymerized ethylene, propylene, and a C to C non-conjugated diene in the proportions of 10 to 90 mole percent ethylene, 5 to 70 mole percent propylene and 0.1 to mole percent of said diene. This is an amphorous material and has an inherent viscosity in the range of 0.2 to 0.9. A preferred composition of this component consists of from 50 to 90 mole percent ethylene, 5 to 45 mole percent propylene and 1 to 5 mole percent diene and is characterized by an inherent viscosity in the range of 0.3 to 0.6.

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The ethylene-propylene-t=erpolymer reactant employed for preparing the additive of the present invention is produced by a polymerization reaction followed by a cracking reaction. A mixture of ethylene, propylene and an unconjugated diene in a suitable solvent is polymerized under atmospheric pressure in the presence of a Ziegler- Natta catalyst to produce an amorphous terpolymer product. Suitable unconjugated 'dienes for the reaction include bi-cyclo (2,2,1) hepta-2,5-diene, 1,4-cyclohexadiene, 1,5 cyclooctadiene, dicyclopentadiene, diisopropenyl benzene, dipentene, 2,2 dimet-hyl-1,5-hexa'diene, 1,5 heptadiene, 1,5-hexadiene, 2-rnethyl-1,4-cyclohexadiene, methylcyclopentadiene dimer, S-methylene-Z-norbornene, 3 methyl-1,5-heptadiene, 2-methyl-1,5-hexadiene, 3-methyl-1,5-hexadiene, 1,7-octadiene, 1,4-pentadiene, 4 vinyl-l-cyclohexene, and 2-methyl-1,4-pentadiene.

The polymerization reaction is conducted by reacting ethylene, propylene and non-conjugated diene in suitable proportions to produce a polymer consisting of 10 to 90 mole percent ethylene, 5 to mole percent propylene, and 0.1 to 20 mole percent of said diene and having an inherent viscosity of at least 1.1. The preferred polymer is one consisting of 50 to mole percent ethylene, 5 to 45 mole percent propylene and 1 to 5 mole percent of .a non-conjugated diene having from 6 to 20 carbon atoms and having an inherent viscosity in the range of 1.1 to 5.

. The inherent viscosity equals the natural log of the specific viscosity divided by the concentration in grams per one hundred ml. The specific viscosity for this equation is the expression of a ratio of the viscosity of the solution divided by the viscosity of the solvent (see Appendix D, page 103, Report No. 4 in Polymer Chemistry by Robert McGovern, Stanford Research Institute, April 1965).

The polymer described must be cracked to a polymer of reduced inherent viscosity. The cracking step can be effected by any conventional cracking process but thermal cracking is preferred. This is preferably accomplished by heating the terpolymer to a temperature in the range of 250 to 450 C. and holding the terpolymer in this temperature range until the polymer has been cracked, generally in a period of time ranging from about 15 seconds to 10 hours. The cracked polymer which is a starting component in the present invention is characterized by consisting of 10 to 90 percent ethylene, 5 to 70 percent propylene and 0.1 to 20 percent of a non-conjugated diene having from 5 to 30 carbon atoms and having an inherent viscosity in the range of 0.2 to 0.9. The polymers are the subject of a copending application S.N. 571,970 filed on Aug. 12, 1966.

Altematively, a suitable low-inherent viscosity ethylene-propylene-terpolymer can be prepared by polymerizing ethylene, propylene and a non-conjugated diene II; the presence of hydrogen and a polymerization cata yst.

Maleic anhydride is reacted with a low inherent viscosity polymer to produce the pour depressant-rust-inhibiting additive of this invention. This reaction is effected by preparng a mixture consisting of about 1 to 50 (preferably from 2 to 15) percent by weight of maleic anhydride and the balance consisting of said polymer followed by heating the mixture at a temperature above about 200 C. until the components have reacted. The reaction will generally be completed at a temperature from ZOO-300 C. in a period of time ranging from about 30 minutes to 12 hours although shorter and longer reaction periods can be employed. The ethylene-propylene-terpolyrner and maleic anhydride are conveniently reacted in mineral oil to produce an oil solution of the reaction prodnet and any unreacted material vacuum stripped from the oil solution. As a further optional reaction, the ethylenepropylene-terpolymer and maleic anhydride reaction product can be further reacted with water, preferably from 5 to 20 weight percent (polymer basis), at a temperature in the range of 80 to 95 C. until at least a portion of the anhydride is converted to the acid. Oil solutions containing from to 50 percent of the reaction product are very convenient for blending into middle distillate oils as well as being convenient for storage.

The additive of the invention is generally employed in a middle distillate mineral oil in a concentration ranging from about 0.001 to 1 weight percent to produce a middle distillate mineral oil fraction having a substantially reduced pour point and improved rust-inhibiting properties. The preferred concentration of the additive is an amount in the range of 0.005 to 0.05 weight percent, amounts which correspond to about and 150 p.t.b. (pounds per thousand barrels).

The following examples illustrate the preparation of the ethylene-propylene-terpolymer component of the reaction product of this invention.

EXAMPLE I An ethylene-propylene gas mixture in the proportion of 2.16 moles of propylene per mole of ethylene was scnubbed by passing the mixture through a packed tower in contact with 50 percent aqueous potassium hydroxide and thereafter drying in a tower packed with Drierite. The dry gas mixture was passed into 400 milliliters of purified n-heptane to saturate the solvent which was maintained at 40 F After saturating the solvent, the gas mixture was continuously fed into the solvent at a rate of 1.0 liter per minute. A third reactant hexadiene-l,5 in the amount of 0.4 gram was added to the solvent containing the reaction mixture. The following polymerization catalysts were used. Catalyst A was a solution of diethyl aluminum chloride in n-'heptane and Catalyst B was a 20 percent solution of tributyl vanadate in n-heptane. One-half cc. of Catalyst A and one-half cc. of Catalyst B were added to the reaction mixture to initiate polymerization. After two minutes, an additional one-half cc. of Catalyst A was added to the reaction mixture and the reaction completed after ten minutes had elapsed.

The reaction product of this reaction contained about 67 mole percent of ethylene, over 32 mole percent propylene and less than 1 mole percent of hexadiene-1,5 and had an inherent viscosity of about 1.69. The foregoing ethylene-propylene-terpolymer was cracked by heating to "a temperature of about 667 F. (353 C.) and maintaining the polymer at this temperature for approximately 5 minutes. The inherent viscosity of the cracked product was 0.50.

EXAMPLE II A gas mixture was prepared consisting of 31.6% ethylene, 60.5% propylene and 7.3% hydrogen. 2 liters of n-heptane at 70 F. was saturated with a portion of the gas mixture followed by the addition of 2 milliliters of dicyclopentadiene to make an n-heptane solution of the olefin monomers. tPolymerization was initiated and continued, at temperatures ranging from 70 F. to 76 F., over twenty minutes by gradually adding 14 milliliters of a 20% solution of diethylaluminum chloride in n-heptane and 3.0 milliliters of a 20% solution of tributylvanadate in n-heptane while continuously passing the ethylene-propylene-hydrogen gas mixture through the reaction mixture.

On completion of the reaction, the polymerization reaction mixture in n-heptane was washed with a dilute aqueous solution of hydrochloric acid. 20 grams of a paratfinic mineral oil having a viscosity of 97 SSU at 100 F. was .added to the reaction mixture and the n-heptane removed by distillation. The mineral oil mixture consisted of about 50% terpolymer which, in turn, consisted of 60 mole percent ethylene, the balance propylene and dicyclopentadiene having an Inherent Viscosity of about 0.316 (1% solution in toluene at 100 F.).

The following examples illustrate the preparation of the reaction product of this invention.

EXAMPLE III A mixture containing equal weights of a naphthenic oil .and an amorphous ethylene-propylene-terpolymer (EPT) consisting of about 60 mole percent ethylene, 39 mole percent propylene and 1 mole percent dicyclopentadiene having an Inherent Viscosity of 2.60 was mixed with equal weight amounts of a refined mineral oil and thermally cracked at 350 C. for about 5 minutes. About 5 weight percent maleic anhydride (basis EPT content) was added and the mixture reacted for 7 hours at 250 C. The reaction product was then vacuum pumped at 250 C. for two hours to remove the unreacted materials leaving the product, designated as Additive A, containing about 27 percent active reaction product in oil.

EXAMPLE IV An ethylene-propylene-terpoly-mer consisting of about 60 percent ethylene, less than 1 percent diene and the balance propylene (Nordel 1070-E) extended with 50% its weight of naphthenic oil was added to an equal weight of a refined mineral oil and the mixture thermally cracked at 350 C. for about 5 minutes. The cracked polymer-oil mixture was heated with 8% maleic anhydride (ethylenepropylene-terpolymer basis) for 7 hours at 250 C. The product was vacuum stripped for two hours at 250 C. The product had an Inherent Viscosity of about 0.560. This product contained about 43 percent active material in the oil solution and was designated Additive B.

EXAMPLE V A mixture containing an equal weight of a refined mineral oil and an ethylene-propylene-terpolymer was prepared as in Example II. The terpolymer contained in this mixture was characterized as follows: 60 mole percent ethylene, the balance propylene and dicyclopentadiene, with an Inherent Viscosity of about 0.463. 13.0 weight percent of maleic anhydride (basis the ethylene-propyleneterpolymer) was added to the mixture and this heated at 250 C. for about 7.0 hours to complete the reaction. The reaction mixture was stripped for 2 hours at 250 C. under light vacuum leaving a 49 percent oil solution of the reaction product. The oil solution was identified as Additive C.

EXAMPLE VI A mixture containing 29 weight percent terpolymer in a refined mineral oil was prepared in a manner similar to Example I using dicyclopentadiene instead of hexadiene- 1,5. The terpolymer oil mixture was thermally cracked at 350 C. for 10 minutes then reacted with 3 weight percent maleic anhydride (terpolymer basis) for 6 hours at 250 C. and then vacuum stripped at 225 C. for two hours. The product had an inherent viscosity of 0.86 (in toluene at 100 F.) and an ethylene content of 45 mole percent. The mixture containing 29 percent solution of the reaction product was designated Additive D.

EXAMPLE VII The thermally cracked amorphous terpolymer described in Example II and 10 weight percent (terpolymer basis) of maleic anhydride were reacted for 5 hours at 210 C., then vacuum stripped 2 hours at 250 C. The reaction mixture was cooled to C. and 10 weight percent (terpolymer basis) water added and stirred at this temperature for 3 hours. The product of this reaction, called Additive E, contained 26% active material.

The pour depressant and rust inhibiting properties of three middle distillate mineral oil fractions containing the additive of this invention was determined. The middle distillate fuels employed in these tests together with their specification and inspection values are listed in the table below.

5 6 TABLE 1 M1DDLE DISTILLATES has been substantially completed, said ethylene-propyl- A B O ene-terpolymer consisting of ethylene, propylene and a non-conjugated diene having from 5 to 30 carbon atoms, ggfg ff ig 1n the mole ratios of from 10 to 90 mole percent ethyl- Flash, PM," F 166 176 ene, to 70 mole percent propylene and 0.1 to 20 mole llififgltgfFKln. at 100 F... 21 i} 238 .3 5 percent of said non-conjugated diene, said ethylene-progou p pylene-terpolymer being amorphous and having an Inist.,AS M, F.IBP 365 392 354 Dist" ASTM, C F 10%" 412 438 m herent Viscosity 1n the range of 0.2 to 0.9. Dlst., ASTM, 2 F 50% 493 2. A fuel 011 composition according to claim 1 in which g g t igggg F 90%. 578 2 to 15 percent by weight basis the polymer of maleic Dis ns'plvrj F 10 anhydride is employed in preparing said reaction product. 5 3L 0 33. 5 3. A fuel oil composition according to claim 1 in which Percent Unsaturate I to said maleic anhydrlde and ethylene-propylene-terpoly- Percent saturates 6Z0 mer reaction product is further reacted with water at a The rust inhibiting properties of middle distillates contemperature m about 9 P v taining the additives of the invention were determined a A fflel 011 composltlon accordmg to 61.2mm 1 m in the ASTM 665 Rusting Test According to this test, which said ethylene-propylene-terpolymer consists of 50 300 milliliters of oil under test and 30 ml. of synthetic sea to 90 mole Percent ethylene 5 45 mole Percent Propyl' water are placed in a glass container and brought to a l f to 5 mole pewst 116116 and has an Inherent temperature of 140 F. A cylindrical steel specimen is Vlscosltym thefange of completely immersed in tht liquid mixture which is main- A 9 O11 composmon accordmg to Clam? 1 tained at a temperature of l40i2 F. for the duration whlch sald ethylene-propylefle-terwlymer conslsts of of the test, namely 24 hours in this case. The results ethylene: Propylene and f of this test are expressed as percent of rusting on the A 3 011 composmon accordmg to clam} 1 m surface of the test specimen. The test results on the addi- 25 Whlch Sald ethylene'propylene'tefpolymel' conslsts of tive containing middle distillate oils are given in the ethylene, Propylene and dlcyclopelltadiefifi table below: 7. A fuel oil composition according to claim 1 contain- TABLE II Middle Distillate A +100 PTB +100 PTB +100 PTB +100 PTB +100 PIB additive A additive B additive C additive D additive E No (contains 27 (contains 43 (contains 50 (29 wt. (25 wt. additive wt. percent wt. percent wt. percent percent percent active active active active active material) material) material) material) material) Pour Point, F 10 30 -25 35 ASTM Rust Test, Percent Rust 100 0 Middle Distillate B Middle Distillate c No +100 PTB +100 PTB +100 PTB No +100 PTB addtive Additive A Additive B Additive E Additive Additive 0 Pour Point, F -10 -25 --30 -20 -10 ASTM Rust Test, Percent Rust 100 1 Few specks. 2 Clean.

. Obviously many modifications and variations of the invention, as hereinafter set forth, may be made Without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A fuel oil composition comprising a major proportion of a middle distillate fuel oil and a minor amount, suflicient to improve pour point and rust inhibiting properties of said fuel oil, of an additive comprising the reaction product of maleic anhydride and an ethylene-propylene-terpolyrner prepared by forming a mixture of from 1 to 50 percent maleic anhydride and the balance said ethylene-propylene-terpolymer and heating said mixture at a temperature above about 200 C. until the reaction References Cited UNITED STATES PATENTS 2,977,334 3/1961 Zopf et a1. 252-56 3,252,772 5/1966 Clough et al. 44-62 3,341,309 9/1967 Ilnyckyj 44-62 DANIEL E. WYMAN, Primary Examiner.

W. H. SHINE, Assistant Examiner.