US 3567639 A
Description (OCR text may contain errors)
United States Patent 01 :"fice 3,567,639 HYDROCARBON-CONTAINING COMPOSITIONS Colin Aaron and Alan Harold Edwards, Charlton,
Wantage, England, and Keith Campbell Tessier, Westfield, N.J., assignors to Esso Research and Engineering Company No Drawing. Filed May 8, 1967, Ser. No. 636,597 Claims priority, application Great Britain, June 1, 1966, 24,368/ 66 Int. Cl. Cm 1/28 US. Cl. 252--56 7 Claims ABSTRACT OF THE DISCLOSURE A pour point depressant for crude oil, shale oil or a fuel oil which comprises 35-100 wt. percent of residua from the distillation of crude or shale oil is disclosed. The pour point depressant is a copolymer of ethylene and a vinyl or C to C hydrocarbyl substituted vinyl ester of a C to C saturated aliphatic monocarboxylic acid, said copolymer having a number average molecular weight of about 4,000 to 60,000 and containing about 40 to 95 wt. percent ethylene.
This invention relates to fuel compositions based on residua-containing fuels, and other base oils.
Although various pour point depressants are known and have been used, they have been reasonably successful only with middle distillate fuels. It has been found difficult to obtain a potent pour point depressant for shale oils, residua or residua-containing fuels. We have now discovered certain polymers which are potent as pour point depressants in certain hydrocarbons, e.g, residua-containing fuels or crude oils.
According to this invention hydrocarbon-containing compositions comprise a major proportion by weight of a residua-containing fuel, shale oil or a crude oil and a minor proportion by weight of a copolymer of ethylene and vinyl (or hydrocarbyl substituted vinyl) ester of a carboxylic acid, said copolymer having a number average molecular weight of above 3,000 and preferably above 3,500.
The residua-containing fuel is defined as a fuel comprising residua from the distillation of crude oil or shale oil or mixtures thereof. Generally the residua-containing fuel (hereinafter referred to simply as the fuel) will contain from about 35% to 100% by weight of residua, and will usually have kinematic viscosities ranging from 10 to 3,500 cs. at 100 F. However, the viscosity of some particularly waxy fuels may be difficult to measure accurately at 100 F., and it is well known in the art that the viscosity of such fuels is measured by the viscosity at a higher temperature. The viscosity at 100 F. is then obtained by extrapolation using a R.E.F.U.T.A.S. viscosity temperature chart. The extrapolated kinematic viscosity will then fall in the desired range at 100 F. The R.E.F.U.T.A.S temperature viscosity chart was designed by C. I. Kelly, M.S.C. Tech., F.I.C., M. Inst., P.T., A.M.I.A.E. Copyright reserved in Great Britain and U.S.A. by Paird & Tatlock (London) Ltd., 14-17 Cross Street, Hatton Garden, London, E.C.1. Fuels having kinematic viscosities of between 15 and 1500 cs. at 100 F. are preferred, and also fuels wherein at least 60% by weight of the fuel boils above 500 F. at atmospheric pressure are particularly suitable.
The fuels to which this invention applies include therefore, light, medium, heavy and bunker or furnace fuels, the viscosities ranging from about 152000 cs. at 100 F., but usually, however, the maximum viscosity will be about 900 cs. at 100 F. Examples of suitable fuels are described in PB Industrial and Marine Fuels of BS2689: 1957.
3,567,639 Patented Mar. 2, 1971 Crude oils from which the fuels are derived, or shale oil may also be used.
The preferred ethylene comonomers are vinyl (or bydrocarbyl, e.g. C to C hydrocarbyl, substituted vinyl) esters of C to C carboxylic acids. The carboxylic acid is preferably aliphatic, and saturated and preferably monocarboxylic. Thus, one may use vinyl propionate, vinyl hexoate, vinyl octanoate, vinyl dodecanoate, vinyl behenoate, isopropenyl acetate, or octadecyl myristoate. The particularly preferred ester is vinyl acetate. The resulting polymer should contain from to 40 weight percent, preferabl 90 to 60 weight percent, of ethylene.
One method of preparing the copolymers involves feeding the monomers into a tubular reactor which has been previously purged with nitrogen. A small amount of oxygen, usually 0.005 to 0.05 wt. percent based on the weight of ethylene is also introduced into the reactor. Alternatively a peroxide initiator, e.g. di-t-butyl peroxide, or a mixture of peroxide initiator and oxygen may be introduced into the reactor in place of oxygen alone. A solvent (e.g. benzene, water, saturated hydrocarbons, methanol) may also be employed in the reaction. The pressure is maintained between 60 and 2700 atmospheres (900 and 40,000 p.s.i.g.), preferably between and 2000 atmospheres (2,000 and 30,000 p.s.i.g.). The temperature should be maintained between 40 C. and 300 C., preferably between 70 C. and 250 C.
Another method of preparing the copolymers is via a batch process. Such a process requires a solvent for the reactants, the solvent being for example toluene or hexane. The preferred solvent however is benzene. The reaction initiator may be any peroxy compound, preferably di-tbutyl peroxide. The temperature of the polymerisation reaction is dependent upon the particular peroxide initiator employed and should be high enough for suflicient decomposition of the initiator to occur. This temperature will usually be between 40 C. and 300 C.
For the preferred initiator, i.e. di-tert-butyl peroxide, the most suitable temperature is between 130 C. and C. The pressure should be between 60 and 1000 atmospheres (900 and 15,000 p.s.i.g.), and preferably being between 75 and 470 atmospheres (1100 and 7000 p.s.i.g.). The autoclave or similar equipment containing the solvent, initiator and vinyl or hydrocarbyl substituted vinyl ester is purged with nitrogen and then with ethylene before charging with a sufficient amount of ethylene to yield the desired pressure when heated to the reaction tempertaure. During the polymerization addition ethylene is added to maintain the pressure at the desired level. Further amounts of initiator and/ or solvent, and/ or vinyl and hydrocarbyl substituted vinyl ester may also be added during the reaction. On completion of the reaction free solvent and unreacted monomers are removed by stripping or some other suitable process yielding the desired polymer.
The copolymers useful in the invention preferably have a number average molecular weight from 3,000 to 60,000 as measured by Vapour Phase Osmometry (using a Mechrolab Vapour Phase Osmometer model 301A) and/or Membrane Osmometry (using a Mechrolab 1 Membrane Osmometer model 501). The number average Heehrolab Inc., 1062 Linda Vista Avenue, Mountain View, Calif.
J tween 0.005 and 0.5% by weight based on the weight of fuel, shale oil, or crude oil.
The copolymer can also be applied down oil wells to crude oil to inhibit the formation of paraffin deposits, or to dissolve existing deposits on the sides of the well casing. The copolymer can also be added to crude oils or residua above ground to facilitate their movement through pipe lines. Thus, for example, the copolymer can be added to any North African crude, to lower the pour points so that they can be more readily pumped.
The blending of the above-mentioned copolymers in fuels, crude oils etc., can be facilitated by first forming copolymer concentrates in suitable hydrocarbon blend stocks. Examples of suitable solvents are those containing a high proportion of aromatic hydrocarbons, e.g. toluene, xylene, kerosene extract, this extract being the highly aromatic fraction separated from a crude kerosene by a liquid sulphur dioxide extraction process. Further suitable solvents are slack waxes, which are the waxes obtained without purification or refining from lubricating oil dewaxing processes. Such suitable slack waxes will usually have melting points between 20 C. and 62 C. and oil contents of to 50 wt. percent.
A suitable composition of such copolymer/solvent blends is 5 to 50% by weight of copolymer, and 95 to 50% by weight of solvent. Thus, for example, particularly suitable blends have been found to be a blend of to 30 e.g. by Weight of an ethylene/vinyl acetate copolymer and 90 to 70% e.g. 75% of a slack wax or a kerosene extract. These compositions can be readily blended into fuels to the required concentrations, e.g. up to 1% by weight, at temperatures of about 40 C. and above.
The copolymers may also be used in the fuels, crude oils, etc. in conjunction with other additives commonly used in fuels, e.g. rust-inhibitors, demulsifying agents, corrosion inhibitors, anti-oxidants or dispersants, or other flow improvers or pour depressants.
EXAMPLE 1 In this example, two copolymers were used, and added in different concentrations to two different fuels.
Copolymer A was a random copolymer of ethylene (67 weight percent and vinyl acetate (33 weight percent) having a number average molecular weight of 13,000 as measured by Vapour Phase Osmometry using chloroform as solvent at 37 C. Copolymer B was a random copolymer of ethylene (82 weight percent) and vinyl acetate (18 weight percent) having a number average molecular weight of 12,000 as measured by Vapour Phase Osmometry using benzene as solvent at 37 C. Both A and B were separately blended with a slack wax so that the blends contained 25% by Weight of A and 25% by weight of B respectively. The slack wax had a melting point of 40 C. and contained 29 wt. percent of oil. The copolymer/slack wax blends were separately blended into two different residual-containing fuel oils C and D having the following characteristics. Fuel oil C contained 32% by weight of distillate fraction boiling between 350 and 680 F., and 68% by weight of residuum with a boiling point of 680+ F., and it had a kinematic viscosity of 43.2 cs. at 100 F. Fuel oil D had an initial boiling point Copolymer eoneen- Upper pour tration, Flow point, F. point, F.
Weight percent 0 D C D Additive:
None 65 25 20 O. 1 25 -15 25 -15 0. 01 30 10 30 25 0. 05 20 10 20 30 O. 01 30 5 5 20 EXAMPLE 2 A 1 gallon stainless steel magnetically stirred autoclave was charged with 840 ml. of benzene and then purged with nitrogen then with ethylene. The autoclave was then heated to 150 C. and pressurised with ethylene to 900 p.s.i.g. 220 g. of vinyl acetate was then introduced via a metering pump over a period of 2 hours. Concurrently a solution of 22 g. of di-tert butyl peroxide in 66 g. of benzene was introduced to the reactor over a period of 3 hours. The temperature was maintained at 150 C. and the pressure at 900 p.s.i.g. during the reaction. After the addition of the peroxide was completed the reaction mass was maintained at 150 C. and 900 p.s.i.g. for an additional 30 minutes. On completion of the reaction the mixture was cooled and the pressure released. Free solvent and unreacted monomers were removed by stripping to give copolymer E.
EXAMPLE 3 Following the procedure given in Example 2, the following copolymers were made using the charges and reaction conditions given in Table I:
TABLE I Polymer preparation G H I J K L Reaction pressure,
p.s.i.g 1, 350 2, 000 3,000 3, 000 4, 000 3,000 Reaction temperature,
150 150 150 135 150 85 Initial charges:
Benzene, ml l, 000 800 800 800 800 800 Vinyl acetate, ml. 80 80 80 S0 Feed rates, ml.,hr
Vinyl acetate 170 140 210 250 Over total time,
hours 1% 2 1% 1% 1% 1% Initiator di-tert butyl peroxide Initiator, n11 l 50 l 20 2 20 2 20 Z 20 3 120 Over total time,
hours 1% 2% 1% 1 5 1% 1 Soak time, hours Polymers H I K L l Lauroyl peroxide. 2 23 wt. di-tert butyl peroxide in benzene. 3 13.8 wt. lauroyl peroxide in benzene.
The polymers prepared in Examples 2 and 3 have the following properties:
POLYMER PROPERTIES 1 Number average molecular Weight measured in toluene solution at 37 C. using a Mechrolab Vapour Phase Osmometer, Model 301A.
2 Weight/volume percent solution in toluene at 100 F.
3 0.02 weight percent of copolymer in fuel oil C as defined in Example I.
4 25 Weight percent copolymer concentrates in toluene were first prepared and these concentrates were used for preparing the fuel oil blends.
b Intrinsic viscosity of 0.17, toluene at 50 C.
EXAMPLE 4 Copolymers I, K and L from Example 3 were blended into residuum M. This residuum has an initial boiling point of 647 F. at atmospheric pressure and a viscosity at 122 F. of 121 Saybolt Furol seconds.
COPOLYMERS IN FUEL M Upper Weight, pour Copolymer 1 percent point None 105 0. 1 90 1 25 weight percent additive concentrates in toluene were used as in Example 3.
EXAMPLE 5 A 25 wt. percent concentrate of copolymer B in a slack wax (as described in Example I) was blended into three crude oils giving the following results.
Upper Upper pour pour Crude oil point point 1 N 70 60 l 25 -5 Q 0 -15 residua from the distillation of crude or shale oil, and
about .001 to 10 wt. percent of a pour depressing copolymer of ethylene and an ester selected from the group consisting of vinyl esters and C to C hydrocarbyl substituted vinyl esters, of C to C saturated aliphatic monocarboxylic acids, said copolymer having a number average molecular weight in the range of about 4,000 to 60,000 and containing about to wt. percent ethylene.
2. A composition according to claim 1, wherein said oil is crude oil and said ester is a vinyl ester.
3. A composition according to claim 2, wherein said molecular weight is in the range of 4,000 to 20,000.
4. A composition according to claim 3, wherein said ester is vinyl acetate.
5. A composition according to claim 1, wherein said oil is fuel oil having at least 60 wt. percent boiling above 500 F. at atmospheric pressure and having a viscosity between 15 and 3,500 cs. at F., and said ester is vinyl ester.
6. A composition according to claim 5, wherein said molecular weight is in the range of 4,000 to 20,000.
7. A composition according to claim 6, wherein said ester is vinyl acetate and said molecular weight is above 5,000.
References Cited UNITED STATES PATENTS 3,048,479 8/ 1959 Ilnyckyj et al. 44--62 3,093,623 6/1963 Ilnyckyj 44-62 3,126,364 3/1964 Ilnyckyj 4462 3,192,165 6/1965 Fields et a1. 44-62 3,254,063 5/1966 Il-nyckyj 4462 3,236,612 2/1966 Ilnyckyj 4462 3,262,873 7/1966 Tiedje et a1 208-33 3,393,144 7/1968 Button et a1. 208-33 PATRICK P. GARVIN, Primary Examiner Y. H. SMITH, Assistant Examiner US. Cl. X.R. 4462