CN117616107A

CN117616107A - Fuel oil compositions, methods and uses related thereto

Info

Publication number: CN117616107A
Application number: CN202280049151.9A
Authority: CN
Inventors: J·L·斯塔克; P·J·比格斯塔夫
Original assignee: Innospec Ltd
Current assignee: Innospec Ltd
Priority date: 2021-07-16
Filing date: 2022-07-08
Publication date: 2024-02-27

Abstract

A fuel oil composition comprising a blended fuel oil having a sulfur content of less than 5000ppm and an additive, wherein the additive is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

Description

Fuel oil compositions, methods and uses related thereto

The present invention relates to fuel oil compositions and to methods and uses related thereto. In particular, the present invention relates to very low sulfur fuel oil (very low sulfur fuel oil, VLSFO) compositions.

In particular, the present invention relates to fuel oils useful in marine applications. Such fuels are commonly referred to as marine diesel (marine fuel oil), marine residual oil (marine residue oil) (residual fuel oil), or marine oil (marine fuel oil). These are typically heavy fuels containing long chain alkanes and alkenes, high molecular weight cycloalkanes, and Gao Chou aromatic (asphaltenes). Such fuels are typically high in sulfur content. Recently, new regulations (IMO 2020) have been introduced by the International Maritime Organization (IMO) to set global limits for sulfur in shipboard fuel oils to 0.50 wt% (5000 ppm by weight). This is a significant reduction compared to the previous 3.5 wt% limit.

In order to comply with new regulations, various methods have been adopted to reduce the sulfur content of these fuels. More catalytic processing of the fuel is typically involved and fuels from multiple sources can be blended to provide a blended fuel having a sulfur content of less than 0.50 wt.%. However, the component fuels mixed into the blend may have very different properties.

This results in fuel stability problems for the new Very Low Sulfur Fuel Oil (VLSFO) according to lMO 2020. The residual and low sulfur distillate streams are typically blended to achieve new sulfur specifications, but the component fuel streams blended to make the fuel may be of variable quality and typically have some level of chemical reactivity. This can lead to oxidation and thermal stability problems of the blended fuel over time, forming gums (guts) or other insoluble materials.

Problems due to asphaltene precipitation in marine fuels have long been known and additives have been developed that help to address these problems and reduce asphaltene precipitation. These additives are known as asphaltene dispersants. However, new stability problems are emerging for new blended VLSFO compositions. It is an object of the present invention to provide VLSFO with improved oxidation and/or thermal stability.

According to a first aspect of the present invention there is provided a fuel oil composition comprising a blended fuel oil having a sulphur content of less than 5000ppm and an additive, wherein the additive is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

The present invention relates to fuel oil compositions having a sulfur content of less than 5000ppm. All references to ppm in this specification refer to parts per million by weight unless otherwise indicated.

The fuel oil composition of the present invention comprises a blended fuel oil. Suitably, the blended fuel oil comprises at least two component fuels. The two or more component fuel oils may be selected from the group consisting of residual fuel oil (residual fuel oils), distillate fuel oil (distillate fuel oils), biologically-derived fuel oil, cracking process stream (cracked process streams), synthetic fuel, and plastic pyrolysis oil (plastic pyrolysis oils).

Residual fuel oil is the heavy fuel component remaining after the distillation or refining process. By residual fuel oil we mean to include atmospheric bottoms (atmospheric tower bottoms) and vacuum bottoms (vacuum tower bottoms). Residual fuel oils that have undergone a hydrotreating or visbreaking process are also considered residual fuel oils.

The residual fuel oil has a high boiling point and a high viscosity, and has a high sulfur and nitrogen content.

Unless hydrotreated, the residual fuel oil contains high levels of sulfur, e.g., up to 5 wt.%, typically 1 to 4 wt.%.

The residual fuel oil typically has a nitrogen content of at least 1000ppm and may have a nitrogen content of at least 2000ppm, for example up to 5000ppm or up to 10000ppm.

The atmospheric bottoms (ATB) typically has a boiling point of 340℃ or higher.

The boiling point of the vacuum bottoms (VTB) is typically 550 ℃ or higher.

The boiling range of visbreaker residues is typically 340 to 540 ℃.

The kinematic viscosity of the residual fuel oil is generally from 10 to 15000mm ² S, preferably 20 to 7500mm ² S, suitably 50 to 1000 mm ² In the range of/s. Visbreaker residues, which are typically derived from VTBs, typically have a lower viscosity than the VTB, typically about one fifth the viscosity of the VTB from which they are derived.

Kinematic viscosity can be measured at 50℃according to ISO 3104.

The pour point of the residual fuel oil may be from-10 to 85 ℃, preferably from-5 to 60 ℃, for example from 0 to 45 ℃.

Pour point may be measured according to ISO 3016.

The asphaltene content of the residual fuel oil is preferably less than 5 wt.%, more preferably less than 2 wt.%, suitably less than 1 wt.%.

Suitable methods for measuring asphaltene content include IP-469 (SARA analysis).

By distillate fuel we mean to include straight run distillate fuels, hydrotreated distillate fuels (e.g. low sulfur diesel fuel or very low sulfur diesel fuel), kerosene, light gas oil, heavy gas oil and vacuum gas oil.

The boiling point of the distillate fuel may be in the range of 180-550 ℃.

The straight-run distillate fuel is obtained directly from the distillation column and used without any further treatment.

The boiling range of the middle distillate fuel oil/diesel fuel oil is suitably from 200 to 350 ℃.

Kerosene typically has a boiling range of 193 to 271 ℃.

The boiling range of light gas oils is typically 271 to 321 ℃.

The boiling range of heavy gas oils is typically 321 to 425 ℃.

The boiling range of light vacuum gas oils is typically 425 to 510 ℃.

The boiling range of heavy vacuum gas oils is typically 510 to 564 ℃.

The sulfur content of straight run middle distillate fuels is typically 0.5 to 2 wt.%. However, distillate fuels are typically hydrotreated in a process that reduces sulfur content.

The sulfur content of the low sulfur diesel fuel is less than 500ppm. In some countries, their sulfur content may be less than 200ppm.

The ultra low sulfur diesel fuel has a sulfur content of less than 50ppm. In some countries, their sulfur content may be less than 15ppm or less than 10ppm.

By cracking process stream we mean the fuel obtained from the catalytic cracking of fuel oil. These fuel components typically contain reactive groups such as olefins. By cracking process stream we mean to include cracked light gas oil, cracked heavy gas oil, light cycle oil, heavy cycle oil and fluid catalytic cracking slurry oil (fluid catalytic cracker slurry oil).

Light cycle oil generally refers to Fluid Catalytic Cracking (FCC) products distilled in the range of 200 to 350 ℃.

Heavy cycle oil generally refers to FCC products distilled in the range of 350 to 500 ℃.

Slurry oils are mixtures comprising FCC residues and catalyst fines (typically silica and/or alumina).

Suitable bio-derived fuel oils include biodiesel fuel and second generation biodiesel fuel. The biodiesel defined by ASTM specification D-6751 (the entire teachings of which are incorporated herein by reference) and EN 14214 is a fatty acid monoalkyl ester of a vegetable or animal oil. Suitable biofuels may be prepared from any fat or oil source, including tallow (tall), but are preferably derived from vegetable oils, such as rapeseed oil, palm kernel oil, coconut oil, corn oil or maize oil, sunflower oil, safflower oil, canola oil (canola oil), peanut oil, cottonseed oil, jatropha oil (jatropha oil), waste edible oil or soybean oil. Preferably, it is a Fatty Acid Alkyl Ester (FAAE). More specifically, the biofuel may include rapeseed oil methyl ester (RME) and/or soybean oil methyl ester (SME) and/or palm oil methyl ester (PME) and/or jatropha oil methyl ester.

The biofuel may suitably be a second generation biodiesel. The second generation biodiesel is derived from the hydrotreatment of renewable resources such as vegetable oils and animal fats. The second generation biodiesel may be similar in performance and quality to petroleum-based fuel oil streams.

Biofuel typically has a very low sulfur content, suitably less than 100ppm. They have boiling points similar to those of fossil distillate fuels.

By synthetic fuel oil we mean to include any synthetically produced hydrocarbon fuel oil, such as those obtained by the fischer-tropsch process (Fischer Tropsch processes). Suitable fuels of this type include heavier fischer-tropsch fuels, for example as described in US 10294431.

Plastic pyrolysis oil is obtained from plastic waste by a thermochemical process based on pyrolysis and hydrotreatment. The boiling range of plastic pyrolysis oil is typically 170 to 370 ℃ and the sulfur content is low, for example less than 100ppm or less than 50ppm.

The fuel oil composition of the present invention comprises a blended fuel oil. This is suitably achieved by blending two or more component fuels.

Preferably, the blended fuel oil comprises at least one residual fuel component and at least one further non-residual fuel component.

Preferably, the blended fuel oil comprises at least 1 wt% residual fuel components.

The blended fuel oil may comprise at least 5 wt% residual fuel components.

The blended fuel oil preferably comprises from 1 to 50 wt% of the residual fuel component.

The blended fuel oil may comprise two or more residual fuel components.

Preferably, the blended fuel oil comprises at least one residual fuel component and at least one further fuel component.

In some embodiments, the blended fuel oil comprises from 5 to 95 weight percent of the residual fuel component and from 95 to 5 weight percent of one or more further fuel components selected from distillate fuel components and/or cracked fuel components.

In some embodiments, the blended fuel oil comprises from 5 to 75 wt%, preferably from 10 to 50 wt% straight run fuel.

In some embodiments, the blended fuel oil comprises from 5 to 75 wt%, preferably from 10 to 50 wt% of the cracking process stream.

In some embodiments, the blended fuel oil comprises 5 to 75 wt%, preferably 10 to 50 wt% light cycle oil.

The properties of the blended fuels depend on the properties of the component fuels from which they are made and the proportions of each fuel in the blend.

The stability of a blended fuel depends on the nature and relative amounts of the component fuels present in the blended fuel.

Residual and cracked components generally lead to reduced stability.

Inclusion of a treated distillate, such as a hydrotreated distillate, and a synthetic fuel tends to improve the stability of the blended fuel.

The sulfur content of the blended fuel oil is less than 5000ppm. The sulfur content may be less than 4000ppm, for example less than 3000ppm, less than 2000ppm or less than 1000ppm.

Preferably, the pour point of the blended fuel oil is from-10 to 40 ℃, preferably from-10 to 25 ℃, more preferably from-10 to 10 ℃ measured according to ISO 3016.

Preferably, the kinematic viscosity of the blended fuel oil is less than 200mm as measured by ISO 3104 at 40 °c ² S, preferably less than 100mm ² S, suitably at 1 and 20mm ² Between/s, preferably 1.4 to 10mm ² /s。

The kinematic viscosity of the blended fuel oil may be 0.1 to 200mm, measured by ISO 3014 at 40 °c ² S, e.g. 1 to 100mm ² S, e.g. 1.4 to 15mm ² /s。

Suitably, the blended fuel oil has an asphaltene content of less than 6 wt%, for example less than 2 wt%, for example less than 0.5 wt%.

The fuel oil composition of the present invention comprises an additive that is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

The copolymer is suitably an alternating copolymer and is prepared by reacting maleic anhydride with an alpha-olefin. Means for carrying out such reactions will be well known to those skilled in the art and are described, for example, in US4240916, US3560456 and US 4151069.

The copolymer additives of the present invention are suitably prepared by reacting maleic anhydride with an alpha-olefin in a molar ratio of from 3:1 to 1:3, preferably from 2:1 to 1:2, more preferably from 1.5:1 to 1:1.5, for example about 1:1.

Preferably, the α -olefin has from 6 to 40 carbon atoms, preferably from 10 to 36 carbon atoms, preferably from 12 to 36 carbon atoms, for example from 16 to 32 carbon atoms. Most preferably, the alpha-olefin has 18 to 30 carbon atoms, for example 20 to 28 carbon atoms.

To form the copolymer additives of the present invention, mixtures of alpha-olefins may be used.

In a preferred embodiment, a mixture of alpha-olefins having 20 to 24 carbon atoms is used.

In one embodiment, mixtures of alpha-olefins having 24 to 28 carbon atoms, such as mixtures having 26 to 28 carbon atoms, are used.

The present invention relates to copolymers comprising maleic anhydride derived units and alpha-olefin derived units.

Copolymers obtained directly from the reaction of an alpha-olefin with maleic anhydride contain alkyl chains and anhydride functional groups.

In some embodiments, the anhydride groups may be further reacted. For example, in some embodiments, the anhydride groups can be hydrolyzed to provide carboxylic acid functional groups.

In some embodiments, the anhydride and/or hydrolyzed acid product may be partially or fully further functionalized, for example by reaction with an amine and/or alcohol to add ester and/or amide and/or imide functionality to the copolymer.

In a preferred embodiment, the copolymer is not further functionalized in this way and the maleic anhydride derived units are present as non-derivatized anhydride moieties and/or as carboxylic acid moieties.

Most preferably, the maleic anhydride derived units of the copolymer contain anhydride groups. Suitably, the additive comprises a copolymer obtained directly from the reaction of an alpha-olefin with maleic anhydride.

The preferred copolymers for use herein have a number average molecular weight of from 1000 to 50000, preferably from 2000 to 40000, suitably from 2500 to 30000, for example from 3000 to 25000.

Preferably, the number average molecular weight of the copolymer is from 5000 to 20000, in one embodiment from 5000 to 10000. In one embodiment, the copolymer has a number average molecular weight of 8000 to 15000.

The copolymer additive is preferably present in the fuel oil composition in an amount of at least 1 ppm, preferably at least 30 ppm.

Preferably, the copolymer additive is present in the fuel oil composition in an amount of from 20 to 10000ppm, preferably from 50 to 5000ppm, suitably from 60 to 3000ppm, more preferably from 100 to 1000ppm.

In some embodiments, the fuel oil compositions of the present invention comprise a single component fuel. The fuel oil composition of the present invention preferably comprises a blended fuel oil formed from two or more component fuels. The copolymer additive of the present invention may be added to the blended fuel or it may be added to the component fuel prior to mixing with the further components.

In formulating blended fuel oils, it is common that one or more of the component fuels used to prepare the blended fuel will be less stable than the other component fuels. For example, some component fuels may be more susceptible to thermal and/or oxidative degradation. Thus, it may be advantageous to add the copolymer additive to a particular component fuel prior to mixing with other component fuels.

In some cases, SARA analysis may be performed on one or more component fuels or blended fuels.

SARA analysis (saturates, aromatics, resins, and asphaltene percentages) can be performed to obtain information about the compositional properties of the blended fuel. SARA analysis was used to determine the performance of the oil that caused the instability and its potential for fouling (fouling) when processed or blended with other oils. Asphaltenes and saturated straight chain hydrocarbons (normal paraffins) can become unstable and precipitate from the oil as the composition, temperature, pressure, and/or time changes. On the other hand, aromatics and resins tend to help stabilize the fuel oil sample.

According to a second aspect of the present invention there is provided a process for preparing a fuel oil composition, the process comprising mixing an additive with a first component fuel and with a second component fuel, wherein the resulting fuel oil composition has a sulphur content of less than 5000ppm, and wherein the additive is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

Preferred features of the second aspect are as defined in relation to the first aspect.

Preferably, the copolymer additive is mixed with the first component fuel prior to mixing the first component fuel with the second component fuel.

The copolymer additive improves the stability of the fuel oil composition of the present invention. Thus, the fuel oil composition of the present invention has improved stability compared to an equivalent fuel oil without additives.

According to a third aspect of the present invention there is provided a method of improving the stability of a blended fuel oil having a sulphur content of less than 5000ppm, the method comprising mixing into the fuel oil an additive which is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

In some embodiments, the additive is incorporated into a component fuel used to prepare a fuel oil composition.

According to a fourth aspect of the present invention there is provided the use of a copolymer comprising maleic anhydride derived units and alpha-olefin derived units as an additive to improve the stability of a blended fuel oil having a sulphur content of less than 5000ppm.

Preferred features of the third and fourth aspects of the invention are as defined in relation to the first aspect.

Further preferred features of the invention will now be described.

The present invention relates to the use of additives to improve the stability of fuel oils having a sulfur content of less than 5000ppm.

By improving the stability of the fuel oil we intend to include any way that can make the additive-added fuel considered more stable than an equivalent non-additive-added fuel.

The improvement in stability can be attributed to reduced degradation caused by heat, light or oxidation.

The improvement in stability may provide for a reduction in the formation of gums, deposits, or other insoluble materials.

The improvement in stability may reduce or inhibit precipitation.

The improved stability may provide improved dispersion of insoluble materials in the fuel.

The improved stability may improve filterability and/or reduce filter clogging.

The improvement in stability may relate to color stability and/or reduced discoloration.

The present invention may provide improved storage stability. The improved storage stability can be measured by reduced sediment formation and/or reduced sedimentation and/or improved filterability and/or improved color stability.

The present invention may provide improved thermal stability. This can be measured by a reduction in the formation of thermal degradation products such as gums and deposits and/or reduced discoloration.

The present invention may provide improved oxidation stability. This can be measured by a reduction in the formation of oxidative degradation products such as gums and deposits and/or reduced discoloration.

A particular advantage of the present invention is the reduction in the levels of gums and insoluble materials that cannot be reduced by conventional asphaltene dispersants used in marine fuel oils. Such additives are known to those skilled in the art and include, for example, alkylphenol resins, sulfonated alkyls, alkyl compounds, and polyester polyamides/imides. Such compounds are described in WO 2009/013236, US9034093 and US 2017/0198174.

The improvement in fuel stability may be measured by any suitable means. Methods by which fuel stability can be measured are well known to those skilled in the art.

One particularly useful way in which the effects of the invention can be measured is by determining the total deposition using the methods described in ISO10307-1 and ISO 10307-2. Alternatively, the effect of the present invention may be measured by determining the total deposition using the method described in ASTM D4870.

Other methods for measuring improved fuel stability include ASTM D4740 point test, ASTM D7061 turbo scan method, ASTM D7112 PORLA method, and ASTM D7157 Rofa method (S values).

Further suitable methods for measuring improved fuel stability include ASTM D97 (fix) -manual pour point; ASTM D4530-micro carbon residue test; ASTM D5949-automatic pour point test; ASTM D7169-paraffin content & profile analysis; IP 469-SARA composition analysis; digital imaging (by cross-polarization microscopy) and particle size assessment.

The fuel oil composition of the present invention may further comprise one or more further additives. Any additives typically incorporated in marine fuels may be included. The formation of suitable fuel compositions and additive packages for fuels will be within the ability of those skilled in the art.

Classes of additives that may be included in the fuel oil compositions of the present invention include:

(i) A conductivity improver;

(ii) A combustion improver;

(iii) An asphaltene dispersant;

(iv) A fuel antioxidant;

(v) A low temperature flow improver;

(vi) Wax anti-settling agent;

(vii) Biofuel instability inhibitors;

(viii) Blending a fuel separation inhibitor;

(ix) Other detergents/dispersants.

Suitable conductivity improver additives (i) for use herein include: α -olefin-sulfone copolymers-polysulfones and quaternary ammonium salts (e.g. as described in US 3811848); polysulphones and quaternary amine/epichlorohydrin adducts dinonylnaphthalene sulphonic acid (e.g. as described in US 3917466); copolymers of alkyl vinyl monomers and cationic vinyl monomers (e.g. as described in US 5672183); alpha-olefin-maleic anhydride copolymers (e.g. as described in US 4416668); alpha-olefin-acrylonitrile copolymers (e.g. as described in US 4388452); alpha-olefin-acrylonitrile copolymers and polymeric polyamines (e.g., as described in US 4259087); copolymers of alkyl vinyl monomers and cationic vinyl monomers and polysulfones (e.g. as described in US 6391070); and acrylic ester-acrylonitrile copolymers and polymeric polyamines (e.g., as described in US4537601 and US 4491651).

In some preferred embodiments, the conductivity improver comprises a polysulfone component.

In some preferred embodiments, the conductivity improver comprises a polymeric nitrogen-containing conductivity improver.

In some preferred embodiments, the conductivity improver comprises a polyamine compound.

In some preferred embodiments, the conductivity improver is a composition comprising both a polyamine component and a polysulfone component, optionally in combination with a quaternary ammonium salt, for example as described in US 3917466.

Preferred conductivity improvers for use in the fuel oil compositions of the invention are described in WO 2009/013236.

Suitable combustion improvers (ii) include metal compounds, organic compounds and mixtures thereof.

Suitable combustion improvers are described in WO 2009/013236.

Some preferred combustion improvers containing metal compounds and organic compounds are described in EP 1899440.

The metal compound is preferably selected from the group consisting of iron compounds, manganese compounds, calcium compounds, cerium compounds, and mixtures thereof.

The organic compound is preferably selected from the group consisting of bicyclic monoterpenes, substituted bicyclic monoterpenes, and mixtures thereof.

Preferably, the organic compound is camphor.

Preferred metal compounds are ferrocene and substituted ferrocenes.

Other suitable combustion improvers are cetane improvers, for example alkyl nitrates or dialkyl peroxides, for example as described in US 20190127657.

One particularly preferred cetane improver is 2-ethylhexyl nitrate.

Suitable asphaltene dispersants (iii) for use in the fuel oil compositions of the present invention include alkoxylated fatty amines or derivatives thereof; oxyalkylating a polyamine; alkane sulfonic acid; aryl sulfonic acid; sarcosinate; ether carboxylic acids; a phosphate ester; carboxylic acids and derivatives thereof; alkylphenol-aldehyde resins; hydrophilic-lipophilic vinyl polymers; alkyl-substituted phenol polyethylene polyamine formaldehyde resins; alkylaryl compounds; alkoxylated amines and alcohols; an imine; an amide; a zwitterionic compound; fatty acid esters; lecithin and derivatives thereof; and derivatives of succinic anhydride and succinamide.

Suitable asphaltene dispersants are described in WO 2009/013236.

A particularly preferred class of asphaltene dispersants for use herein are alkylphenol resins, such as those described in paragraphs [0017] to [0038] of US 2007221539. Particular preference is given to compounds derived from C3 to C12 alkyl or alkenyl phenols, in particular nonylphenol.

A combination of an alkylphenol resin and a poly (meth) acrylate as described in US5021498 can be used as an asphaltene dispersant.

Further suitable asphaltene dispersants include alkoxylated fatty polyamines, for example as described in US6488724 and US 5421993. Alkoxylated derivatives of simple polyamines are also useful, such as block copolymers derived from ethylenediamine, ethylene oxide, and propylene oxide. Examples of such compounds are available under the trademark GENAPOL (RTM) from Clariant.

Suitable fuel antioxidants (iv) for use in the present invention include phenolic antioxidants, sulfurized phenolic antioxidants and aromatic amine antioxidants.

Suitable antioxidants are described, for example, in WO 2009/013236, US3556748 and US 5509944.

Preferred antioxidants for use herein are aromatic amines, such as phenylenediamine.

The low temperature flow improvers (v) useful in the present invention include copolymers of olefins and unsaturated esters, alkyl methacrylate polymers, polyoxyalkylene esters, ethers, esters/ethers, and mixtures thereof.

Suitable low temperature flow improvers for use herein are described in WO 2009/013236 and US 2017/023670.

Particularly preferred low temperature flow improvers are ethylene vinyl acetate copolymers and terpolymers. These are described, for example, in paragraphs [0026] to [0032] of US 20170233670.

Typical copolymers are those of ethylene and vinyl esters such as vinyl acetate. Propylene may also be included.

The terpolymer may further comprise vinyl neodecanoate, vinyl 2-ethylhexanoate, methyl acrylate (methyl acrylate), or 2-ethylhexyl acrylate.

Another preferred class of low temperature flow improvers are comb polymers. These are known to those skilled in the art and include:

-polyalkyl (meth) acrylate or copolymer thereof;

maleic anhydride-alpha-olefin copolymers which are subsequently reacted with alcohols (e.g. C10 to C28 alcohols) to form esters or subsequently with primary fatty amines;

vinyl fumarate copolymers, such as vinyl fumarate acetate; and

-poly (alpha-olefin) homo-or copolymers.

Some suitable comb polymers are described in paragraphs [0067] to [0070] of US 20170233670.

Wax anti-settling agents (vi) useful as stabilizers in the present invention include certain polyimides and maleic anhydride olefin copolymers.

Suitable additives of this type for use herein are described in WO 2009/013236.

Other suitable wax sedimentation additives include: those described in US4402708, such as the reaction products of phthalic anhydride and ditallowances fatty amides; combinations of such additives and ethylene vinyl acetate copolymers, for example as described in US 4481013; fatty amide derivatives described in US 5071445; and copolymers described in US5391632, including in particular the compound of comparative example 25.

Further compounds useful as wax anti-settling agents and/or low temperature flow inhibitors are described in EP 743972 and EP 743974.

Biofuel instability inhibitors (vii) have the primary function of dispersing polymers or high molecular weight compounds found as by-products of oxidation or thermal decomposition in biofuels. Biofuel instability inhibitors useful herein include polymers of: ethylene and unsaturated esters; vinyl alcohol, vinyl ether, and esters thereof with organic acids; adducts of propylene, ethylene, isobutylene and unsaturated carboxylic acids (e.g., maleic and fumaric acid) and their amide or imide derivatives; acrylic acids and their amide or ester derivatives; a polystyrene; and polymers made from combinations of these monomers.

The function of the blended fuel separation inhibitor (viii) is to maintain two or more fuels in dispersed or blended form. Loss of fuel homogeneity and flowability may also occur when there is phase separation within such fuels. The fuel blend can typically be made in a tank at the time of ship berthing and any available fuel locally available can be obtained at a preferential price. For example, when two or more different distillate fuels are blended, or when a biofuel is blended with a distillate fuel, a lack of stability may occur.

Many compounds that are inhibitors of blended fuel separation include the compounds described above, and the selection of suitable additives will be within the ability of those skilled in the art.

Detergent/dispersant compounds (ix) suitable for use herein include any generally known detergent compounds, either nitrogen-containing or non-nitrogen-containing. Such compounds typically include a long chain hydrophobic tail and a polar head group. Suitable hydrophobic groups are polyisobutene groups, and polar head groups may contain nitrogen and/or oxygen containing functional groups, such as amides, amines, succinimides, acids and esters.

Preferred acylated nitrogen-containing dispersants are the reaction products of a carboxylic acid-derived acylating agent and an amine containing at least one primary or secondary amine group.

One preferred acylated nitrogen-containing compound for use herein is prepared by reacting a poly (isobutylene) -substituted succinic acid-derived acylating agent (e.g., anhydride, acid, ester, etc.) with a mixture of ethylene polyamines wherein the poly (isobutylene) substituents have a number average molecular weight (Mn) of 170 to 2800, each ethylene polyamine having 2 to about 9 amino nitrogen atoms, preferably about 2 to about 8 nitrogen atoms, and about 1 to about 8 ethylene groups.

Particularly preferred polyisobutenyl succinimide additives include those obtained from the condensation reaction of a polyisobutenyl succinic anhydride derived from a polyisobutene having a Mn of about 750 or about 1000 with a polyethylene polyamine mixture having an average composition close to tetraethylenepentamine.

Preferred further additives for inclusion in the fuel oil compositions of the present invention include acylated nitrogen-containing dispersants, alkylphenol-aldehyde resins, and phenylenediamine antioxidants.

In a preferred embodiment, the phenolic resin is a substituted phenolic resin. More preferably, the phenolic resin is the reaction product of a substituted phenol and an aldehyde.

More preferably, the phenolic resin is the reaction product of a substituted phenol with an aldehyde having 1 to 22 carbon atoms, preferably 1 to 7 carbon atoms, such as formaldehyde.

Preferably, the phenolic resin is C ₉ -C ₂₄ Phenolic resin.

More preferably, the phenolic resin is C ₉ -C ₂₄ Reaction products of phenols with formaldehyde, or reaction products of tert-butylphenols with aldehydes having from l to 22 carbon atoms, preferably from 1 to 7 carbon atoms, for example formaldehyde.

Preferred additives for improving the low temperature performance of fuel oil compositions are described in US 2017/023670.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having 20 to 24 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and 5 to 75 wt%, preferably 10 to 50 wt% straight run distillate fuel component.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having from 26 to 28 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and from 5 to 75 wt%, preferably from 10 to 50 wt% straight run distillate fuel component.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having 20 to 24 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and 5 to 75 wt%, preferably 10 to 50 wt% cracked fuel component.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having from 26 to 28 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and from 5 to 75 wt%, preferably from 10 to 50 wt% cracked fuel component.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having 20 to 24 carbons and a blended fuel oil comprising at least l weight percent of residual fuel component and 5 to 75 weight percent, preferably 10 to 50 weight percent, of straight run distillate fuel component, wherein the copolymer has a number average molecular weight of 5000 to 10000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having 20 to 24 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and 5 to 75 wt%, preferably 10 to 50 wt% straight run distillate fuel component, wherein the copolymer has a number average molecular weight of 8000 to 15000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having 20 to 24 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and 5 to 75 wt%, preferably 10 to 50 wt% cracked fuel component, wherein the copolymer has a number average molecular weight of 5000 to 10000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having 20 to 24 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and 5 to 75 wt%, preferably 10 to 50 wt% cracked fuel component, wherein the copolymer has a number average molecular weight of 8000 to 15000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having from 26 to 28 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and from 5 to 75 wt%, preferably from 10 to 50 wt% straight run distillate fuel component, wherein the copolymer has a number average molecular weight of from 5000 to 10000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having from 26 to 28 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and from 5 to 75 wt%, preferably from 10 to 50 wt% straight run distillate fuel component, wherein the copolymer has a number average molecular weight of from 8000 to 15000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having from 26 to 28 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and from 5 to 75 wt%, preferably from 10 to 50 wt% cracked fuel component, wherein the copolymer has a number average molecular weight of from 5000 to 10000.

In some preferred embodiments, the first, second, third or fourth aspects of the invention may involve the use of a copolymer comprising underivatized maleic anhydride derived units and units derived from a mixture of alpha-olefins having from 26 to 28 carbons and a blended fuel oil comprising at least 1 wt% residual fuel component and from 5 to 75 wt%, preferably from 10 to 50 wt% cracked fuel component, wherein the copolymer has a number average molecular weight of from 8000 to 15000.

The invention will now be further described with reference to the following non-limiting examples.

Example 1

Additives a to D (invention) were prepared by reacting equimolar amounts of alpha-olefin and maleic anhydride in the presence of a free radical initiator and a solvent for 5 hours. The reaction conditions are summarized in table 1. After the reaction was completed, the reaction solvent was removed under reduced pressure to provide a polymer product, which was then diluted to a polymer concentration of 40 wt% using Aromatic 150 solvent.

GPC analysis of Molecular Weight (MW) distribution is also shown in Table 1.

Using WatersThe HR column was subjected to Gel Permeation Chromatography (GPC) eluting with tetrahydrofuran (1 mL/min) at 39 ℃. The refractive index was measured and the product molecular weight distribution (Mn, mw and polydispersity) was calculated relative to polystyrene standards. />

TABLE 1

* Tert-butyl peroxy-2-ethylhexanoate, commercially available from Nouryon

Example 2

Additives a to D shown in table 1 were added to a marine fuel conforming to IMO 2020 standard. The marine fuel comprises a blend of distillate and residual fuel components having a TSE value of 0.09% (m/m) as measured by ISO 10307-1.

A comparative fuel composition was prepared by metering known asphaltene dispersants E, F, G, H and I into the same fuel.

The composition information of the additives used in the comparative examples is shown in table 2.

TABLE 2

The fuel composition was then subjected to a heptane dispersant test in the following manner:

fuel oil (0.1 g) with or without additives was added to heptane (6.77 g,9.9 mL) in a graduated centrifuge tube. After thorough mixing, the centrifuge tube was allowed to stand at ambient temperature for 18 hours. The samples were then visually evaluated and given a good, medium or poor dispersibility rating.

Samples were also tested without additives. The results of the heptane dispersant test are shown in table 3.

TABLE 3 Table 3

* For the test without additive, visual inspection was performed after 1 hour

The additives of the present invention exhibit better dispersion of gums and deposits present in the IMO 2020 compliant marine fuel when compared to the comparative examples. FIG. 1 shows the centrifuge tubes of entries 7 and 1 (from left to right) of Table 3 after they have been allowed to stand at ambient temperature for 18 hours.

Example 3

The effect of the additives of the present invention on TSP (potential total deposit) was evaluated in different VLSFOs comprising blends of distillate and residual fuel components.

The TSE (deposit without heat aging) of the fuel was determined to be 0.13% (m/m) prior to testing with the additive. SARA analysis (IP-469) provided 49.8 wt.% saturates, 36.50 wt.% aromatics, 8.80 wt.% resin, and 4.90 wt.% asphaltenes.

Total deposit (TSE) was measured according to ISO 10307-1. The results are expressed as mass percent of the total deposit, accurate to 0.01% (m/m).

Potential Total Sediment (TSP) was measured according to ISO10307-1 by heat aging the test sample at 100 ℃ for 24 hours according to ISO10307-2 (procedure a) followed by heat filtration. The results are expressed as mass percent of the total deposit, accurate to 0.01% (m/m).

The composition information of the additives used in the comparative examples is shown in table 4.

TABLE 4 Table 4

Additive agent	Composition information
		J	Amine-based stability additives
K	Phenolic resin, high molecular weight

TSP was then measured and the results are shown in table 5.

TABLE 5TSP measurement

The results indicate that the test fuel is unstable. For fuel without additive, the TSP results (0.42% m/m) were significantly higher than the TSE (0.13% m/m). Unexpectedly, additive B of the present invention was very effective in stabilizing the test fuel (table 5, entry 2). For the fuel with additive B, the measured TSP was substantially unchanged from the TSE without the fuel.

Claims

1. A fuel oil composition comprising a blended fuel oil having a sulfur content of less than 5000ppm and an additive, wherein the additive is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

2. The fuel oil composition of claim 1, wherein the fuel oil comprises at least one distillate fuel component and at least one residual fuel component.

3. The fuel oil composition of claim 2, wherein the fuel oil comprises from 5 to 95 wt.% of residual fuel components and from 5 to 95 wt.% of one or more fuel components selected from distillate fuel components and cracked fuel components.

4. The fuel oil composition of any preceding claim, wherein the maleic anhydride derived units of the copolymer are present as underivatized anhydride moieties and/or as carboxylic acid moieties.

5. The fuel oil composition of any preceding claim, wherein the alpha-olefin derived units contain from 12 to 36 carbon atoms.

6. The fuel oil composition of any preceding claim, wherein the maleic anhydride/a-olefin copolymer is present in an amount of 50 to 5000ppm.

7. The fuel oil composition of any preceding claim, wherein the number average molecular weight of the copolymer additive is from 5000 to 20000.

8. The fuel oil composition according to any preceding claim comprising one or more further additives selected from the group consisting of:

(i) A conductivity improver;

(ii) A combustion improver;

(iii) An asphaltene dispersant;

(iv) A fuel antioxidant;

(v) A low temperature flow improver;

(vi) Wax anti-settling agent;

(vii) Biofuel instability inhibitors;

(viii) Blending a fuel separation inhibitor;

(ix) Other detergents/dispersants.

9. The fuel oil composition of any preceding claim, wherein the additive-containing fuel oil has improved stability compared to an equivalent unadditized fuel oil.

10. A method of preparing a fuel oil composition, the method comprising mixing an additive with a first component fuel and with a second component fuel, wherein the resulting fuel oil composition has a sulfur content of less than 5000ppm, and wherein the additive is a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

11. The method of claim 10, wherein the additive is mixed with the first component fuel prior to mixing the first component fuel with the second component fuel.

12. The method of claim 10 or 11, wherein one or more further component fuels are mixed to provide the fuel oil composition.

13. A method of improving the stability of a blended fuel oil having a sulfur content of less than 5000ppm, the method comprising mixing an additive into the fuel oil, the additive being a copolymer comprising maleic anhydride derived units and alpha-olefin derived units.

14. The method of claim 13, wherein the additive is mixed into a component fuel used to prepare the fuel oil composition.

15. Use of a copolymer comprising maleic anhydride derived units and alpha-olefin derived units as an additive to improve the stability of a blended fuel oil having a sulphur content of less than 5000ppm.

16. The method or use according to any one of claims 13 to 15, wherein the improvement in stability is measured by improved storage stability and/or improved thermal stability and/or improved oxidative stability.