WO2019173154A1

WO2019173154A1 - (meth)acrylate copolymer compositions and use thereof as pour point depressants for crude oil

Info

Publication number: WO2019173154A1
Application number: PCT/US2019/020347
Authority: WO
Inventors: Michael T. PETR; Lu Bai; Gregoire Cardoen; Ralph C. Even; Wei Gao; Andrew Hughes; Joseph Manna; Stephanie L. Potisek; Larisa Mae Q. REYES
Original assignee: Rohm And Haas Company; Dow Global Technologies Llc
Priority date: 2018-03-05
Filing date: 2019-03-01
Publication date: 2019-09-12

Abstract

The present invention relates to a pour point depressant composition comprising a copolymer composed of (i) a C₁₆ to C₆₀ alkyl ester of (meth)acrylate comonomer, (ii) a C₁ to C₈ alkyl ester of (meth)acrylate comonomer, and optionally (iii) a vinylic comonomer and a method to make and use said composition.

Description

(METH)ACRYLATE COPOLYMER COMPOSITIONS AND USE THEREOF AS POUR POINT DEPRESSANTS FOR CRUDE OIL

FIELD OF THE INVENTION

This invention relates to a copolymers and copolymer compositions and use thereof as an additive for inhibiting the deposition of paraffin and improving the flow properties of crude oils, condensates fuel oil, diesel oil and middle distillates, particularly in low temperature or offshore applications.

BACKGROUND OF THE INVENTION

Underground crude oil formations typically have relatively high temperatures. After underground production of the crude oil, it is transported to the surface, where it cools down to a greater or lesser degree according to the production temperature and the storage or transport conditions.

According to their origin, crude oils have different proportions of waxes, which consist essentially of long-chain n-paraffms. According to the type of crude oil, the proportion of such paraffins may typically be 1 to 30 percent by weight of the crude oil. When the temperature goes below a particular level in the course of cooling, the paraffins can crystallize, typically in the form of platelets. The precipitated paraffins considerably impair the flowability of the oil. The platelet-shaped n-paraffm crystals can form a kind of house-of-cards structure which encloses the crude oil, such that the crude oil ceases to flow, even though the predominant portion is still liquid. The lowest temperature at which a sample of an oil still just flows in the course of cooling is referred to as the pour point ("yield point"). For the measurement of the pour point, standardized test methods are used. Precipitated paraffins can block filters, pumps, pipelines and other installations or be deposited in tanks, thus entailing a high level of cleaning. The deposit temperature of wax deposits can be above room temperature, anywhere from about -20°C to l00°C. Crude oil is produced from such deposits while still warm, and it naturally cools more or less quickly to room temperature in the course of or after production, or else to lower temperatures under corresponding climatic conditions. Crude oils may have pour points above room temperature, such that crude oils of this kind may solidify in the course of or after production.

It is known that the pour point of crude oils can be lowered by suitable additives. This can prevent paraffins from precipitating in the course of cooling of produced crude oil. Suitable additives firstly prevent the formation of said house-of- cards-like structures and thus lower the temperature at which the crude oil solidifies. In addition, additives can promote the formation of fine, well-crystallized, non

agglomerating paraffin crystals, such that undisrupted oil transport is ensured. Such additives are also referred to as pour point depressants or flow improvers.

Paraffin inhibitors or wax inhibitors refer to those substances intended to prevent the deposition of paraffins or paraffin waxes on surfaces in contact with crude oils or other wax-containing oils and/or mineral oil products.

USP 5,179,182 discloses Ci -30 (meth)acrylate copolymers used as a pour point depressant.

USP 5,281,329 discloses a pour depressant that is a mixture of two

(meth)acrylate polymers wherein the two comonomers having specific crystallization temperatures differing by at least 5°C.

EP2081970 disclose a methacrylate copolymer pour point depressant made with 60 to 96 weight percent C12 to C i6 methacrylate and 4 to 40 weight percent C is to C30 methacrylate having a Mw of 5,000 to 250,000 g/mol.

USP 2005/0215437 discloses a methacrylate copolymer pour point depressant made with 1 to 98 weight percent C1-30 alkyl ester of acrylic acid, 1 to 98 weight percent C1-30 alkyl ester of methacrylic acid, and 1 to 30 weight percent of one or more olefmic monomers, said copolymer having a Mn of 1,000 to 150,000 g/mol and a polydispersity ranging from 1.8 to 4.5. Particularly advantageous pour point depressants can be obtained by preparing said graft copolymers based on ethylene-vinyl ester copolymers using alkyl

(meth)acrylates having Cis to C22 carbon groups. See USP 2016/0032200A1 which discloses a methacrylate copolymer pour point depressant made with 50 to 90 weight percent C12-60 (meth)acrylate and 1 to 49 weight percent C1-12 (meth)acrylate made in the presence of an ethylene vinyl ester copolymer. However, such products have the disadvantage that the solutions thereof in hydrocarbons, especially the concentrates mentioned, can solidify in the course of cooling to room temperature. They accordingly first have to be melted for use, which means additional work for the user.

Such graft copolymers for use as pour point depressants are typically prepared in chemical production sites, and the products are transported from there to the site of use, for example to an oilfield or to an offshore platform. Such sites of use may be in cold regions of the earth. In order to save transport costs, concentrates of the graft copolymers in hydrocarbons are typically produced, for example concentrates having a polymer content of 50 to 80 percent by weight of polymers. Such concentrates can be used as such or can be formulated by users on site in the desired manner to give ready - to-use formulations. For example, dilution with solvent and/or addition of further additives is possible. SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide improved pour point depressants for crude oils.

The present invention is such an improved pour point depressant composition and method of use.

In one embodiment, the present invention is a pour point depressant composition comprising a copolymer composed of: (i) from 55 to 95 weight percent of one or more Ci₆ to C60 alkyl ester of (meth)acrylic acid comonomer, (ii) from 10 to 60 weight percent of one or more Ci to Cs alkyl ester of (meth)acrylic acid comonomer, and (iii) from 0 to 25 weight percent of a vinylic comonomer selected from a C9 to C15 (meth)acrylate, diene, styrene, a substituted styrene, a vinyl alcohol, a vinyl ether, a vinyl ester, a vinyl halide, or a vinyl nitrile, preferably (iii) is styrene, butadiene, isoprene, alpha methyl styrene, vinyl acetate, vinyl chloride, dodecyl methacrylate, allyl alcohol, ethyl vinyl ether, acrylonitrile, allyl alcohol, ethyl vinyl ether, or vinyl acetate, wherein the copolymer has a molecular weight of 1,000 to 1,000,000 g/mol and a poly dispersity equal to or less than 4.

In one embodiment of the present invention, comonomer (i) has the formula:

H₂C=C(R²)-COOR³ where R² is H or a methyl group and R³ is an alkyl group having 16 to 60 carbon atoms, preferably R³ is l-hexadecyl, l-octadecyl, l-nonadecyl, l-eicosyl, l-heneicosyl, 1- docosyl, l-tetracosyl, l-hexacosyl, l-octacosyl, or l-triacontyl.

In one embodiment of the present invention, comonomer (ii) has the formula:

H₂C=C(R²)-COOR⁴ where R² is H or a methyl group and R⁴ is an alkyl group selected from R^4a, R^4b, or R^4c groups where R^4a is a linear alkyl group having 1 to 8 carbon atoms, R^4b is a branched alkyl group having 3 to 8 carbon atoms, and R^4c is a cyclic alkyl group having 5 to 8 carbon atoms, preferably R⁴ is methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n- heptyl, n-octyl, i-butyl, t-butyl, 2,2'-dimethylpropyl, 2-ethylhexyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, or cycloheptyl.

In one embodiment of the present invention the pour point depressant composition described herein above further comprises a hydrocarbon solvent, a stabilizing agent, a freezing point depressant, a biocide, a colorant, an anti-foaming agent, or a mixture thereof.

Another embodiment of the present invention is a method of improving the pour point of an oil, preferably the oil is crude oil, condensate, middle distillate, fuel oil, or diesel, which comprises the step of adding to said oil from 0.001 to 1 percent, by weight of said oil, of a copolymer composed of: (i) from 55 to 95 weight percent of one or more Ci₆ to C6o alkyl ester of (meth)acrylic acid comonomer, (ii) from 10 to 60 weight percent of one or more Ci to Cs alkyl ester of (meth)acrylate acid monomer, and (iii) from 0 to 25 weight percent of a vinylic comonomer selected from a diene, styrene, a substituted styrene, a vinyl alcohol, a vinyl ether, a vinyl ester, a vinyl halide, or a vinyl nitrile, preferably (iii) is styrene, butadiene, isoprene, styrene, alpha methyl styrene, vinyl acetate, vinyl chloride, acrylonitrile, allyl alcohol, ethyl vinyl ether, or vinyl acetate, wherein the copolymer has a molecular weight of 1,000 to 1,000,000 g/mol and a polydispersity equal to or less than 4.

In another embodiment of the method of the present invention, the pour point depressant composition described herein above further comprises a hydrocarbon solvent, a stabilizing agent, a freezing point depressant, a biocide, a colorant, an anti foaming agent, or a mixture thereof.

DETAILED DESCRIPTION OF THE INVENTION

Pour point depressants reduce the pour point of crude oils, mineral oils and/or mineral oil products. The pour point ("yield point") refers to the lowest temperature at which a sample of an oil, in the course of cooling, still just flows. For the measurement of the pour point, standardized test methods are used, for example ASTM D-97 “Standard Test Method for Pour Point of Petroleum Products.”

The (meth)acrylate copolymers of the invention described herein below may be used as pour point depressants for oil, crude oil, mineral oil and/or mineral oil products, by adding at least one of the copolymer formulations specific to the oil, crude oil, mineral oil and/or mineral oil products.

"Alkyl" means a monovalent group derived from a straight, branched chain or cyclic saturated hydrocarbon by the removal of a single hydrogen atom. Representative alkyl groups include methyl, ethyl, n- and iso-propyl, hexyl, octyl, lauryl, eicosanyl, cetyl, stearyl, behenyl, cyclohexyl, and the like. "Alkyl ester of acrylic acid" means a monomer of formula H2C=CHC02R’ where R’ is Cito C6o alkyl or Cs to C15 cycloalkyl where cycloalkyl is defined herein. Representative alkyl esters of acrylic acid include methyl, hexyl acrylate, octyl acrylate, decyl acrylate, stearyl acrylate, eicosanyl acrylate, lauryl acrylate, behenyl acrylate, and the like.

"Alkyl ester of methacrylic acid" means a monomer of formula

H2C=C(CH3)C02R” where R” is Ci to C6₀ alkyl or C5 to C15 cycloalkyl where cycloalkyl is defined herein. Representative alkyl esters of methacrylic acid include methyl, hexyl methacrylate, octyl methacrylate, decyl methacryl ate, stearyl

methacrylate, eicosanyl methacrylate, lauryl methacrylate, behenyl methacrylate, and the like.

"(Meth)acrylate monomer" means a monomer of an acrylate, a methacrylate, or mixtures thereof.

“Copolymer” means a polymer comprising more than one monomer, in other words a polymer comprising two or more comonomers, three or more comonomers, four or more comonomers, four or more comonomers, etc.

“(Meth)acrylate copolymer” means a copolymer comprising two or more different (meth)acrylate comonomers.

The (meth)acrylate copolymers of the present invention comprise, consist essentially of, or consist of (i) one or more Ci₆ to C60 alkyl ester of (meth)acrylate comonomer and (ii) one or more Ci to Cs alkyl ester of (meth)acrylate comonomer and optionally (iii) one or more vinylic comonomer.

The first comonomer (i) of the (meth)acrylate copolymer of the present invention has the general formula H2C=C(R²)-COOR³ where R² is H or a methyl group and R³ is a alkyl group having 16 to 60 carbon atoms, preferably 18 to 30 carbon atoms and, for example, 18 to 24 carbon atoms. R³ may be a l-hexadecyl, l-octadecyl, 1- nonadecyl, l-eicosyl, l-heneicosyl, l-docosyl (behenyl), l-tetracosyl, l-hexacosyl, 1- octacosyl or l-triacontyl. It will be appreciated that it is also possible to use a mixture of various alkyl (meth)acrylates (i). For example, it is possible to use mixtures in which R³ represents Ci₆ and C ix groups or Cis, C20, and C22 groups. In a preferred embodiment, at least one of the alkyl (meth)acrylates (i) used is l-docosyl (meth)acrylate (behenyl (meth)acrylate), i.e. R³ is a linear alkyl group having 22 carbon atoms. In a particularly preferred embodiment of the invention, at least 40% by weight of the alkyl (meth)acrylates (i) used is l-docosyl (meth)acrylate.

Advantageously, it is possible to use mixtures comprising l-octadecyl (meth)acrylate, l-eicosyl (meth)methacrylate and l-docosyl (meth)acrylate. Such mixtures of various (meth)acrylates are also commercially available. As well as the C18/C20/C22

(meth)acrylates mentioned, they may also comprise small amounts of (meth)acrylates with a higher or lower carbon number as by-products. For example, mixtures may comprise 40 to 55% by weight of l-octadecyl (meth)acrylate, 10 to 15% by weight of l-eicosyl (meth)methacrylate and 35 to 45% by weight of l-docosyl (meth)acrylate.

The comonomer (i) is present in the (meth)acrylate copolymer in an amount equal to or greater than 55 weight percent where weight percent is based on the combined weight of comonomers (i), (ii), and (iii), if present. The comonomer (i) is present in the (meth)acrylate copolymer in an amount equal to or less than 90 weight percent, preferably equal to or less than 80, and more preferably equal to or less than 70 weight percent where weight percent is based on the combined weight of comonomers (i), (ii), and (iii), if present.

The second comonomer (ii) of the (meth)acrylate copolymer of the present invention has the general formula H2C=C(R²)-COOR⁴ where R² is as already defined and R⁴ is an alkyl group, preferably a saturated aliphatic hydrocarbyl group selected from the group of R^4a, R^4b and R^4c groups and the groups are each defined as follows:

R^4a: linear alkyl groups having 1 to 8, preferably 1 to 4 and more preferably 1 to 2 carbon atoms,

R^4b: branched alkyl groups having 3 to 8, preferably 3 to 6, more preferably 4 to

6, carbon atoms, and

R^4c: cyclic alkyl groups having 5 to 8 or preferably 5 to 6 carbon atoms.

Examples of linear alkyl groups R^4a comprise methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl, preference being given to methyl, ethyl, n- propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl, particular preference to methyl and ethyl and very particular preference to methyl.

Branched alkyl groups R^4b may be singly or multiply branched. Examples of branched R^4b groups comprise i-butyl, t-butyl, 2,2'-dimethylpropyl, 2-ethylhexyl, preference being given to t-butyl and 2-ethylhexyl.

Cyclic alkyl groups may R^4c may be monocyclic or polycyclic, especially bicyclic. They may additionally be substituted by linear and/or branched alkyl groups. Examples of cyclic alkyl groups R^4c comprise cyclopentyl, cyclohexyl, 4- methylcyclohexyl, or cycloheptyl.

In one embodiment of the invention, the R⁴ groups are R^4a and R^4b groups.

In a further preferred embodiment, the R⁴ groups are R^4c groups, preferably R^4c groups having 5 to 68 carbon atoms.

It will be appreciated that it is also possible to use a mixture of various alkyl (meth)acrylates (ii).

The comonomer (ii) is present in the (meth)acrylate copolymer in an amount equal to or greater than 10 weight percent, preferably equal to or greater than 20, and more preferably equal to or greater than 30 weight percent where weight percent is based on the combined weight of comonomers (i), (ii), and (iii), if present. The comonomer (ii) is present in the (meth)acrylate copolymer in an amount equal to or less than 60 weight percent, preferably equal to or less than 50, and more preferably equal to or less than 40 weight percent where weight percent is based on the combined weight of comonomers (i), (ii), and (iii), if present.

The third comonomer (iii) of the (meth)acrylate copolymer of the present invention is selected from a (meth)acrylate (e.g., dodecyl methacrylate) diene (e.g., butadiene), isoprene, styrene, substituted styrenes (e.g., alpha methyl styrene), vinyl alcohols (allyl alcohol), vinyl ethers (ethyl vinyl ether), vinyl esters (e.g., vinyl acetate), vinyl halides (e.g., vinyl chloride), and vinyl nitriles (e.g., acrylonitrile).

The comonomer (iii) is present in the (meth)acrylate copolymer in an amount equal to or greater than 0 weight percent, preferably equal to or greater than 5, and more preferably equal to or greater than 10 weight percent where weight percent is based on the combined weight of comonomers (i), (ii), and (iii), if present. The comonomer (iii) is present in the (meth)acrylate copolymer in an amount equal to or less than 25 weight percent, preferably equal to or less than 20, and more preferably equal to or less than 15 weight percent where weight percent is based on the combined weight of comonomers (i), (ii), and (iii), if present.

In one embodiment, the (meth)acrylate copolymer of the invention consists of only comonomer (i), comonomer (ii), and comonomer (iii).

In one embodiment, the (meth)acrylate copolymer of the invention consists of only comonomer (i), and comonomer (ii).

In one embodiment the (meth)acrylate copolymer of the invention does not contain a comonomer having the formula H2C=C(R²)-COOR⁵ where R² is H or a methyl group and R⁵ is an alkyl group having 9 to 15 carbon atoms.

In general, the (meth)acrylate copolymers are formed by solution

polymerization in an organic solvent or aqueous emulsion or suspension polymerization in the presence of an initiator, such as a thermal initiator like a peracid, e.g., persulfate, a peroxide, or an organic peroxide, or a redox pair, such as a peracid or peroxide and a reducing agent like a bisulfite or an organic sulfoxylate. Such polymerization methods are conventional in the art such as, for example, USP 4,325,856; 4,654,397; and 4,814,373.

When solution polymerization in an organic solvent is used to form the

(meth)acrylate copolymers, a feed process is used to deliver the comonomer mixture to the reactor over time, in order to maintain a low monomer concentration. To do so the comonomer mixture is pumped at a constant rate using any kind of pump, such as parastaltic, piston, diaphragm, syringe, etc. In addition, extra organic solvent is supplied to the reactor before polymerization to further dilute all the monomer that is subsequently fed to the reactor to form the (meth)acrylate copolymer.

The (meth)acrylate copolymer of the present invention preferably has a weight average molecular weight (Mw) of 1,000 to 1,000,000 g/mol, more preferably 10,000 to 200,000 g/mol, even more preferably 30,000 to 100,000 g/mol. The (meth)acrylate copolymer of the present invention preferably has a polydispersity of 1 to 4, more preferably 2 to 4, more preferably 2 to 3.5, and more preferably 2.5 to 3.

The (meth)acrylate copolymer of the present invention preferably has a viscosity equal to or less than 4,000 cP in the temperature range from 25°C to -20°C as a 25 percent solution in toluene or aromatic- 150, more preferably less than 1,000 cP, and more preferably less than 500 cP, and more preferably less than 300 cP.

The (meth)acrylate copolymer of the present invention preferably has a viscosity equal to or less than 80,000 cP in the temperature range from 25°C to 4°C as a 50 percent solution in toluene or aromatic- 150, more preferably less than 40,000 cP, and more preferably less than 10,000 cP.In one embodiment, the present invention is a method of inhibiting the deposition of paraffins and improving the flow properties of oil comprising adding to the oil an effective amount of the copolymer of this invention. Effective copolymer doses are typically 1 to 2,500 ppm based on the oil. The amount is preferably 50 to 1500 ppm, more preferably 100 to 600 ppm and, for example, 250 to 600 ppm. The amounts are based on the copolymeric composition itself, not including any solvents present and optional further components of the formulation.

In another embodiment of the present invention, this invention is a method of inhibiting the deposition of paraffins and improving the flow properties of oil comprising adding to the oil an effective amount of a polymer composition comprising an effective amount of the copolymer of this invention and one or more solvents, preferably a hydrocarbon solvent. Suitable solvents include toluene, xylene, high aromatic naphtha, mineral oil, iso-paraffinic solvent (isopar), Arivasol, kerosene, methylene chloride, acetonitrile, methyl sulfoxide, and the like. The pour point depressant composition preferably comprises 1 to 60 weight percent, more preferably 25 to 50 weight percent of copolymer, based on polymer actives.

The copolymer composition is diluted with solvent to the requisite level or blended with water to form a dispersion. The composition can be added to the pipeline by batch or continuous injection or squeezing, upstream or downstream of the location of any potential cold area likely to result in deposition of wax, gellation, thickening, sludging, etc. Also, the copolymer composition can be added at the cold area

(reservoir, tank, container, etc.) to decrease the pour point of crude oil, condensate, middle distillate, etc.

However, in some instances, the composition may be either too viscous or solid at the required paraffin-inhibiting concentration, especially at the low temperature (- 30°C to about lO°C), conditions that may be experienced by the oil during its travel through the pipeline e.g. from an offshore platform. In such cases, the composition may be further diluted with a suitable solvent as described above as necessary.

In one embodiment of this invention, the pour point depressant composition is liquid at a temperature of 0°C.

In another embodiment of the present invention, the pour point depressant composition comprises 1 to 60 weight percent of the copolymer based on polymer actives.

In another embodiment of the present invention, the pour point depressant composition comprises 25 to 50 weight percent of the copolymer based on polymer actives.

In another embodiment of the present invention, the oil is crude oil, condensate or middle distillate.

In a preferred aspect, the oil is crude oil.

In another preferred aspect, the oil is fuel oil or diesel.

In one embodiment of this invention, the pour point depressant dispersion composition of the present invention can be added to an oil pipeline by batch or continuous injection or squeezing, upstream or downstream of the location of any potential cold area likely to result in deposition of wax, gellation, thickening, sludging, etc. Also, the copolymer composition can be added at the cold area (reservoir, tank, container, etc.) to decrease the pour point of the oil.

In a preferred embodiment of the invention, the oil is crude oil and the formulation is injected into a crude oil pipeline. The injection can preferably be affected at the oilfield, i.e., at the start of the crude oil pipeline, but the injection can of course also be affected at another site. More particularly, the pipeline may be one leading onshore from an offshore platform. Explosion protection is particularly important on offshore platforms and in refineries, and the inventive formulations based on solvents having a flashpoint equal to or greater than 60°C accordingly simplify working quite considerably. Moreover, the cooling of crude oil in underwater pipelines leading onshore from an offshore platform is naturally particularly rapid, especially when the pipelines are in cold water, for example having a water temperature of less than lO°C.

In a further embodiment of the invention, the oil is crude oil and the formulation is injected into a production well. Here too, the production well may especially be a production well leading to an offshore platform. The injection is preferably effected approximately at the site where oil from the formation flows into the production well.

In this way, the solidification of the crude oil in the production well or an excessive increase in its viscosity can be prevented.

In another embodiment of the present invention, the pour point depressant composition may consist of the copolymer alone or in combination with other additives including dewaxing auxiliaries, corrosion inhibitors, asphaltene inhibitors, scale inhibitors, antioxidants, lubricity additives, dehazers, conductivity improvers, cetane number improvers, sludge inhibitors, and the like.

The foregoing may be better understood by the following Examples, which are presented for purposes of illustration and are not intended to limit the scope of this invention.

EXAMPLES

In Tables 1 “Mw” is weight average molecular weight and“PDI” is polydispersity index both of which are determined by gel permeation chromatography (GPC) on an Agilent 1100 Series High Pressure Liquid Chromatograph (HPLC) with two 20pm MIXED-A columns using tetrahydrofuran as the mobile phase and diluent at lmL/min and room temperature.

Examples 1 and 2 and the Comparative Examples A and B are synthesized with solution polymerization using the following procedure and the values of the variable parameters in Table 1. First, 40.82g of a monomer solution is mixed with 44.75 weight percent behenyl methacrylate (45.2 weight percent Cis, 10.4 weight percent C20, and 43.4 weight percent C22), 29.53 weight percent methyl methacrylate, and the remainder solvent. Then the reactor solvent is added to the reactor, followed by the monomer shot and then 0.7lg of the tert-butyl peroxy-2-ethylhexanoate initiator shot solution in Table 2, and then stirred and heated to l00°C for 20 minutes. Then the remaining monomer and 6.59g of the initiator solution with the concentrations in Table 1 are fed at l00°C for 3 hours. Then half of l.55g of a 20.15 weight percent tert-butyl peroxy-2- ethylhexanoate solution is added and stirred at l00°C for 5 minutes followed by the other half. Finally, the dilution solvent is added and the solution is cooled.

Table 1

In Table 1, Pour point depression is determined using the North America crude oiland Appalachian crude oil. First, the oil is heated oil for 1 hour at 50°C. Then lpL of the PPD solution is added to a vial followed by 0.5mL of oil and then shaken. Then the vial is heated for 1 hour at 50°C, and finally, the pour point is measured with the Instrumentation Scientifique de Laboratoire MPP 5Gs Pour Point Analyzer.

Table 2

The data in Error! Reference source not found.2 clearly illustrates the benefit of the inventive Examples over the Comparative Examples. Example 9 and

Comparative Example C have comparable molecular weights, but the lower polydispersity of Example 9 increases the pour point reduction. The same is also true for Example 10 and Comparative Example D, which have lower molecular weights than that of the first set but are comparable to that of each other.

Claims

What is claimed is:

1. A pour point depressant composition comprising a copolymer composed of:

(i) from 55 to 95 weight percent of one or more Ci6 to C6o alkyl ester of (meth)acrylate comonomer,

(ii) from 10 to 60 weight percent of one or more Ci to Cs alkyl ester of

(meth)acrylate comonomer,

and

(iii) from 0 to 25 weight percent of a vinylic comonomer selected from a diene, styrene, a substituted styrene, a vinyl alcohol, a vinyl ether, a vinyl ester, a vinyl halide, or a vinyl nitrile,

2. wherein the copolymer has a molecular weight of 1,000 to 1,000,000

g/mol and a poly dispersity equal to or less than 4. The pour point depressant composition of Claim 1 wherein (i) has the formula

H₂C=C(R²)-COOR³ where R² is H or a methyl group

and

R³ is an alkyl group having 16 to 60 carbon atoms.

3. The pour point depressant composition of Claim 2 wherein R³ is l-hexadecyl, l-octadecyl, l-nonadecyl, l-eicosyl, l-heneicosyl, l-docosyl, l-tetracosyl, l-hexacosyl, l-octacosyl, or l-triacontyl.

4. The pour point depressant composition of Claim 1 wherein (ii) has the formula

H₂C=C(R²)-COOR⁴ where R² is H or a methyl group

and

R⁴ is an alkyl group selected from R^4a, R^4b, or R^4c groups where R^4a is a linear alkyl group having 1 to 8 carbon atoms,

R^4b is a branched alkyl group having 3 to 8 carbon atoms,

and

R^4C is a cyclic alkyl group having 5 to 8 carbon atoms.

5. The pour point depressant composition of Claim 4 wherein R⁴ is methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, i-butyl, t-butyl, 2,2'- dimethylpropyl, 2-ethylhexyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, or cycloheptyl.

6. The pour point depressant composition of Claim 1 wherein (iii) is present in an amount equal to or greater than 1 weight percent and equal to or less than 25 weight percent and is styrene, butadiene, isoprene, styrene, alpha methyl styrene, vinyl acetate, vinyl chloride, lauryl methacrylate, allyl alcohol, ethyl vinyl ether, acrylonitrile, allyl alcohol, ethyl vinyl ether, or vinyl acetate.

7. The pour point depressant composition of Claim 1 further comprising a hydrocarbon solvent, a stabilizing agent, a freezing point depressant, a biocide, a colorant, an anti-foaming agent, or a mixture thereof.

8. A method of improving the pour point of an oil which comprises adding to said oil from 0.001 to 1 percent, by weight of said oil, of a pour point depressant composition comprising a copolymer composed of:

(i) from 55 to 95 weight percent of one or more C i6 to C60 alkyl ester of

(meth)acrylate monomer,

(ii) from 10 to 60 weight percent of one or more Ci to Cs alkyl ester of

(meth)acrylate monomer,

and

(iii) from 0 to 25 weight percent of a vinylic comonomer selected from a

(meth)acrylate, diene, styrene, a substituted styrene, a vinyl alcohol, a vinyl ether, a vinyl ester, a vinyl halide, or a vinyl nitrile,

wherein the copolymer has a molecular weight of 1,000 to 1,000,000 g/mol and a poly dispersity equal to or less than 4.

9. The method of Claim 8 wherein the oil is crude oil, condensate, middle distillate, fuel oil, or diesel.

10. The method of Claim 8 wherein the pour point depressant composition further comprises a hydrocarbon solvent, a stabilizing agent, a freezing point depressant, a biocide, a colorant, an anti-foaming agent, or a mixture thereof.