The present invention relates to pyrolysis oils and methods and uses relating thereto. In particular the invention relates to additives for improving the stability of compositions comprising waste rubber pyrolysis oils or waste plastic pyrolysis oils.

Pyrolysis oils are the fluids generated from the pyrolysis of waste, for example plastic waste, used tyres, waste rubber, biomass for example agricultural waste, forestry waste, waste cooking oils and algae waste. Examples of waste plastic which may be pyrolysed to produce plastic pyrolysis oils include polyethylene, polypropylene, polystyrene, polyethylene terephthalates (PET) and mixtures thereof. Oils obtained from the pyrolysis of plastics are commonly referred to as waste plastic pyrolysis oils (WPPOs). Oils obtained from the pyrolysis of rubber (e.g. from tyres) are commonly referred to as waste rubber pyrolysis oils (WRPOs). The organic liquid produced by pyrolysis of rubber, plastics and other waste materials has a very dark colour, an unpleasant odour and is unstable. However there is a strong desire to find a use for such oils to avoid such waste being sent to landfill or polluting oceans.

Pyrolysis oils can be used as a feedstock for chemical processing, for example in the production of polymers such as polyethylene. They may also be used in fuel oils. The use of pyrolysis oils to produce polymers represents a sustainable alternative to the use of crude oil feedstocks.

The utility of pyrolysis oils is limited due to their poor oxidation stability. This is believed to be due to oxidation of oxygen or nitrogen containing species present in the oil. The nature of these oils and their method of production means that they typically comprise a greater proportion of components that are susceptible to oxidation than mineral derived middle distillate fuels.

Pyrolysis oils can be optionally hydrotreated or cracked before subsequent use. Such processes may increase their oxidation stability. Alternatively they may be treated with chemical additives to improve their stability.

The present inventors have found that certain compounds are effective at improving the oxidation stability of compositions comprising pyrolysis oils. Furthermore, the inventors have found that such compounds are effective at improving the storage stability of compositions comprising pyrolysis oils. According to a first aspect of the present invention there is provided a composition comprising a pyrolysis oil and, as an additive:

(a) one or more nitrogen containing antioxidants.

The first aspect of the present invention relates to a composition comprising a pyrolysis oil. The pyrolysis oil may be obtained from the pyrolysis of any type of waste. The components of the oil and the properties thereof will depend on the types of waste that was pyrolysed and the pyrolysis conditions. For example the pyrolysis oil may be obtained from the pyrolysis of plastic waste, rubber waste, agricultural waste, forestry waste, waste cooking oils and algae waste.

Preferably the pyrolysis oil comprises a plastic pyrolysis oil. The plastic pyrolysis oil may be obtained from the pyrolysis of any type of plastic.

Preferred plastic pyrolysis oils are obtained from the more pyrolysis of one or more polymers selected from polyethylene, polypropylene, PET, rubber and mixtures thereof,

Preferred plastic pyrolysis oils are obtained from the more pyrolysis of one or more polymers selected from polyethylene, polypropylene, PET, rubber, used tyres and mixtures thereof.

In one especially preferred embodiment the pyrolysis oil is obtained from the pyrolysis of rubber. For example, the pyrolysis oil may be obtained from the pyrolysis of used tyres.

In some embodiments the pyrolysis oil in the composition of the first aspect may be a hydrotreated pyrolysis oil.

In some embodiments the pyrolysis oil in the composition of the first aspect have been treated using a cracking process.

In preferred embodiments the composition of the first aspect comprises a pyrolysis oil directly obtained from a pyrolysis plant without purification or further treatment.

In some embodiments the pyrolysis oil has and n-paraffin content of less than 15 wt%. Preferably less than 10 wt%, for example less than 6 wt%.

In some embodiments the pyrolysis oil has an asphaltene content of less than 5 wt%.

Preferably less than 2 wt%, for example less than 1 wt% In some embodiments the composition of the first aspect may comprise a blended fuel oil comprising a pyrolysis oil and one or more fuel oils from hydrocarbon and/or renewable sources. Preferably the pyrolysis oil is a waste plastic pyrolysis oil (WPPO) or a waste rubber pyrolysis oil (WRPO).

Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of other components The term “consisting essentially of’ or “consists essentially of' means including the components specified but excluding other components except for components added for a purpose other than achieving the technical effect of the invention. The term “consisting of' or “consists of” means including the components specified but excluding other components.

Whenever appropriate, depending upon the context, the use of the term “comprises” or “comprising" may also be taken to include the meaning "consists essentially of or “consisting essentially of', and also may also be taken to include the meaning “consists of’ or “consisting of’.

In some embodiments the composition of the first aspect comprises a blended fuel oil comprising a pyrolysis oil (preferably a WPPO or WRPO) and a middle distillate fuel oil.

The middle distillate fuel oil may comprise a petroieum-based fuel oil, especially a middle distillate fuel oil. Such distillate fuel oils generally boil within the range of from 110°C to 500°C, e.g 150°C to 400°C. The middle distillate fuel oil may comprise atmospheric distillate or vacuum distillate, cracked gas oil, or a blend in any proportion of straight run and refinery streams such as thermally and/or catalytically cracked and hydro-cracked distillates.

The middle distillate fuel oil may comprise non-renewable Fischer-Tropsch fuels such as those described as GTL (gas-to-liquid) fuels, CTL (coal-to-fiquid) fuels and OTL (oil sands-to-liquid).

The middle distillate fuel oil may comprise a renewable fuel such as a biofuel composition or biodiesel composition.

The middle distillate fuel oil may comprise 1st generation biodiesel. First generation biodiesel contains esters of, for example, vegetable oils, animal fats and used cooking fats. This form of biodiesel may be obtained by transesterification of oils, for example rapeseed oil, soybean oil, safflower oil, palm oil, palm kernel oil, corn oil, peanut oil, cotton seed oil, tallow, coconut oil, physic nut oil (Jatropha), sunflower seed oil, used cooking oils, hydrogenated vegetable oils or any mixture thereof, with an alcohol, usually a monoalcohol, in the presence of a catalyst. The middle distillate fuel oil may comprise second generation biodiesel. Second generation biodiesel is derived from renewable resources such as vegetable oils and animal fats and processed, often in the refinery, often using hydroprocessing such as the H-Bio process developed by Petrobras. Second generation biodiesel may be similar in properties and quality to petroleum based fuel oil streams, for example renewable diesel produced from vegetable oils, animal fats etc. and marketed by ConocoPhillips as Renewable Diesel and by Neste as NExBTL.

The middle distillate fuel oil used in the present invention may comprise third generation biodiesel. Third generation biodiesel utilises gasification and Fischer-Tropsch technology including those described as BTL (biomass-to-liquid) fuels. Third generation biodiesel does not differ widely from some second generation biodiesel, but aims to exploit the whole plant (biomass) and thereby widens the feedstock base.

The middle distillate fuel oil may contain blends of any or all of the above diesel fuel oils.

In some embodiments the middle distillate fuel oil may be a blended diesel fuel comprising biodiesel. In such blends the bio-diesel may be present in an amount of, for example up to 0.5%, up to 1 %, up to 2%, up to 3%, up to 4%, up to 5%, up to 10%, up to 20%, up to 30%, up to 40%, up to 50%, up to 60%, up to 70%, up to 80%, up to 90%, up to 95% or up to 99%.

In some embodiments the middle distillate fuel oil may comprise a secondary fuel, for example ethanol. Preferably however the diesel fuel composition does not contain ethanol.

The middle distillate fuel oil may contain a relatively high sulphur content, for example greater than 0.05% by weight, such as 0.1 % or 0.2%.

However in preferred embodiments the middle distillate fuel oil has a sulphur content of at most 0.05% by weight, more preferably of at most 0.035% by weight, especially of at most 0.015%. Fuels with even lower levels of sulphur are also suitable such as, fuels with less than 50 ppm sulphur by weight, preferably less than 20 ppm, for example 10 ppm or less

Various metal species may be present in the middle distillate fuel oil. This may be due to contamination of the fuel during manufacture, storage, transport or use or due to contamination of fuel additives. Meta! species may also be added to fuels deliberately. For example transition metals are sometimes added as fuel borne catalysts, for example to improve the performance of diesel particulate filters. In preferred embodiments the middle distillate fuel oil used in the present invention comprise sodium and/or calcium. Preferably they comprise sodium. The sodium and/or calcium is typically present in a total amount of from 0.01 to 50 ppm, preferably from 0.05 to 5 ppm preferably 0,1 to 2ppm, such as 0,1 to 1 ppm.

Other metal-containing species may also be present as a contaminant, for example through the corrosion of metal and metal oxide surfaces by acidic species present in the fuel or from lubricating oil. In use, fuels such as diesel fuels routinely come into contact with metal surfaces for example, in vehicle fuelling systems, fuel tanks, fuel transportation means etc Typically, metal-containing contamination may comprise transition metals such as zinc, iron and copper: other group I or group II metals and other metals such as lead.

In addition to metal-containing contamination which may be present in middle distillate fuel oils there are circumstances where metal-containing species may deliberately be added to the fuel. For example, as is known in the art, metal-containing fuel-borne catalyst species may be added to aid with the regeneration of particulate traps.

Metal-containing contamination, depending on its source, may be in the form of insoluble particulates or soluble compounds or complexes. Metal-containing fuel-borne catalysts are often soluble compounds or complexes or colloidal species.

In some embodiments, the middle distillate fuel oil may comprise metal-containing species comprising a fuei-borne catalyst. Preferably, the fuel borne catalyst comprises one or more metals selected from iron, cerium, platinum, manganese, Group I and Group II metals e.g., calcium and strontium. Most preferably the fuel borne catalyst comprises a metal selected from iron and cerium.

In some embodiments, the middle distillate fuel oil may comprise metal-containing species comprising zinc. Zinc may be present in an amount of from 0.01 to 50 ppm, preferably from 0,05 to 5 ppm, more preferably 0.1 to 1 ,5 ppm.

The composition of the first aspect comprises (a) one or more nitrogen containing antioxidants.

Any suitable nitrogen containing antioxidant may be used.

Suitable nitrogen containing antioxidants will be known to the person skilled in the art.

Suitable amino based antioxidants include aromatic amines, hindered amines, N-oxides, substituted hydroxylamines, and acylated nitrogen compounds. Suitable aromatic amines include diaminobenzene and alkylated diamino benzenes, especially dialkylated and trialkylated diaminobenzenes, for example p-phenylenediamine, 3,5- diethyitoluene-2,4-diamine; 3,5-diethyltoluene-2,2-diamine; 2,4,6-triethylbenzene-2,6-diamine alkylated diphenyl amines; diphenylamines and alkylated diphenylamines, for example N,N- diphenyl-1 ,4-phenylenediamines; and naphthyiamines, for example N-phenyl-1-napthylamine and N-phenyl-2-naphthylamine.

Suitable hindered amines include secondary and tertiary aliphatic amines, for example dimethyl cyclohexylamine.

Suitable N-oxides include TEMPO and derivatives thereof.

Preferably the one or more nitrogen containing antioxidants (a) are selected from:

(i) acylated nitrogen compounds;

(ii) phenyfenediamines;

(iii) substituted hydroxylamines; and

(iv) mixtures thereof.

Suitable acylated nitrogen compounds (i) may be made by reacting a carboxylic acid acyiating agent with an amine and are known to those skilled in the art. In such compounds the acylating agent is linked to the amino compound through an imido, amido, amidine or acyloxy ammonium linkage.

Preferred acylated nitrogen-containing compounds are hydrocarbyl substituted. The hydrocarbyl substituent may be in either the carboxylic acid acylating agent derived portion of the molecule or in the amine derived portion of the molecule, or both. Preferably, however, it is in the acylating agent portion. A preferred class of acylated nitrogen-containing compounds suitable for use in the present invention are those formed by the reaction of an acylating agent having a hydrocarbyl substituent of at feast 8 carbon atoms and a compound comprising at least one primary or secondary amine group.

The acylating agent may be a mono- or polycarboxylic acid (or reactive equivalent thereof) for example a substituted succinic, phthalic or propionic acid or anhydride.

Suitable hydrocarbyl substituted acylating agents and means of preparing them are well known in the art

Illustrative of hydrocarbyl substituent based groups containing at least eight carbon atoms are n-octyl, n-decyl, n-dodecyf, tetrapropenyl, n-octadecyl, oleyl, chloroctadecyi, triicontanyl, etc. The hydrocarbyl based substituents may be made from homo- or interpolymers (e.g. copolymers, terpolymers) of mono- and di-olefins having 2 to 10 carbon atoms, for example ethylene, propylene, butane-1, isobutene, butadiene, isoprene, 1 -hexene, 1 -octene, etc. Preferably these olefins are 1 -monoolefins,

The term “hydrocarbyr as used herein denotes a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly aliphatic hydrocarbon character.

The hydrocarbyl-based substituents are preferably predominantly saturated, that is, they contain no more than one carbon-to-carbon unsaturated bond for every ten carbon-to-carbon single bonds present. Most preferably they contain no more than one carbon-to-carbon nonaromatic unsaturated bond for every 50 carbon-to-carbon bonds present.

The hydrocarbyl substituent in such acylating agents preferably comprises at least 10, more preferably at least 12, for example at least 30 or at least 40 carbon atoms It may comprise up to about 200 carbon atoms Preferably the hydrocarbyl substituent of the acylating agent has a number average molecular weight (Mn) of between 170 to 2800, for example from 250 to 1500, preferably from 500 to 1500 and more preferably 500 to 1100. An Mn of 700 to 1300 is especially preferred. In a particularly preferred embodiment, the hydrocarbyl substituent has a number average molecular weight of 700 - 1000, preferably 700 - 850 for example 750.

The carboxylic acid-derived acylating agent may comprise a mixture of compounds. For example a mixture of compounds having different hydrocarbyl substituents may be used. In some embodiments the acylating agent may have more than one hydrocarbyl substituent. In such embodiments each hydrocarbyl substituent may be the same or different.

Preferred hydrocarbyl-based substituents are polyisobutenes. Such compounds are known to the person skilled in the art.

Preferred hydrocarbyl substituted acylating agents are polyisobutenyl succinic anhydrides. These compounds are commonly referred to as "PIBSAs” and are known to the person skilled in the art.

Conventional polyisobutenes and so-called "highly-reactive" polyisobutenes are suitable for use in the invention. Highly reactive polyisobutenes in this context are defined as polyisobutenes wherein at least 50%, preferably 70% or more, of the terminal olefinic double bonds are of the vinylidene type as described in EP0565285. Particularly preferred polyisobutenes are those having more than 80 mof% and up to 100 mol% of terminal vinylidene groups such as those describeci in US7291758. Preferred polyisobutenes have preferred molecular weight ranges as described above for hydrocarbyl substituents generally.

Other preferred hydrocarbyl groups include those having an internal olefin for example as described in the applicant's published application W 02007/015080.

An internal olefin as used herein means any olefin containing predominantly a non-alpha double bond, that is a beta or higher olefin. Preferably such materials are substantially completely beta or higher olefins, for example containing less than 10% by weight alpha olefin, more preferably less than 5% by weight or less than 2% by weight. Typical internal olefins include Neodene 1518IQ available from Shell.

Internal olefins are sometimes known as isomerised olefins and can be prepared from alpha olefins by a process of isomerisation known in the art, or are available from other sources. The fact that they are also known as internal olefins reflects that they do not necessarily have to be prepared by isomerisation

Preferred carboxylic acid-derived acylating agents are polyisobutenyl substituted succinic anhydrides or PiBSAs. Especially preferred PIBSAs are those having a PIB molecular weight (Mn) of from 300 to 2800, preferably from 450 to 2300, more preferably from 500 to 1300.

The carboxylic acid-derived acylating agent is reacted with an amine. Suitably it is reacted with a primary or secondary amine Examples of some suitable amines will now be described.

Amine compounds useful for reaction with the acylating agents include polyalkylene polyamines of the general formula:

(R ) _£ N[U-N(R )] _n R wherein each R ³ is independently selected from a hydrogen atom, a hydrocarbyl group or a hydroxy-substituted hydrocarbyl group containing up to about 30 carbon atoms, with proviso that at least one R ³ is a hydrogen atom, n is a whole number from 1 to 10 and U is a C1-18 alkylene group. Preferably each R ³ is independently selected from hydrogen, methyl, ethyl, propyl, isopropyl, butyl and isomers thereof. Most preferably each R ³ is ethyl or hydrogen. U is preferably a C1-4 alkylene group, most preferably ethylene.

Other useful amines include heterocyclic-substituted polyamines including hydroxyalkylsubstituted polyamines wherein the polyamines are as described above and the heterocyclic substituent is selected from nitrogen-containing aliphatic and aromatic heterocycles, for example piperazines, imidazolines, pyrimidines, morpholines and derivatives thereof. Other useful amines for reaction with acylating agents include aromatic polyamines of the general formula:

Ar(NR%) _y wherein Ar is an aromatic nucleus of 6 to 20 carbon atoms, each R ³ is as defined above and y is from 2 to 8.

Specific examples of polyalkylene polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, tri(tri-methylene)tetramine, pentaethylenehexamine, hexaethylene-heptamine, 1 ,2-propylenediamine, and mixtures thereof. Other commercially available materials which comprise complex mixtures of polyamines may also be used. For example, higher ethylene polyamines optionally containing all or some of the above in addition to higher boiling fractions containing 8 or more nitrogen atoms etc. Specific examples of hydroxyalkyl-substituted polyamines include N-(2- hydroxyethyl) ethylene diamine, N,N‘ -bis(2-hydroxyethyl) ethylene diamine, N-{3-hydroxybutyl) tetramethylene diamine, etc. Specific examples of the heterocyclic-substltuted polyamines (2) are N-2-aminoethyl piperazine, N-2 and N-3 amino propyl morpholine, N-3(dimethyl amino) propyl piperazine, 2-heptyl-3-(2-aminopropyl) imidazoline, 1 ,4-bis (2-aminoethyl) piperazine, 1- (2-hydroxy ethyl) piperazine, and 2-heptadecyl-1-(2-hydroxyethyl)-imidazoline, etc. Specific examples of the aromatic polyamines (3) are the various isomeric phenylene diamines, the various isomeric naphthalene diamines, etc.

Preferred amines are polyethylene polyamines including ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethylene- heptamine, and mixtures and isomers thereof.

In preferred embodiments the reaction product of the carboxylic acid derived acylating agent and an amine includes at least one primary or secondary amine group.

A preferred acylated nitrogen-containing compound for use herein is prepared by reacting a poly(isobutene)-substituted succinic acid-derived acylating agent (e.g., anhydride, acid, ester, etc.) wherein the poly(isobutene) substituent has a number average molecular weight (Mn) of between 170 to 2800 with a mixture of ethylene polyamines having 2 to about 9 amino nitrogen atoms, preferably about 2 to about 8 nitrogen atoms, per ethylene polyamine and about 1 to about 8 ethylene groups. These acylated nitrogen compounds are suitably formed by the reaction of a molar ratio of acylating agentamino compound of from 10:1 to 1 :10, preferably from 5:1 to 1:5, more preferably from 2:1 to 1 :2 and most preferably from 2:1 to 1 :1. In especially preferred embodiments, the acylated nitrogen compounds are formed by the reaction of acylating agent to amino compound in a molar ratio of from 1.8:1 to 1 :1.2, preferably from 1.6:1 to 1:1.2, more preferably from 1.4:1 to 1 :1.1 and most preferably from 1.2:1 to 1 :1. Acylated amino compounds of this type and their preparation are well known to those skilled in the art and are described in for example EP0565285 and US5925151 .

In especially preferred embodiments the acylated nitrogen-containing additive (i) comprises the reaction product of a polyisobutene-substituted succinic acid or succinic anhydride and a polyethylene polyamine to form a succinimide detergent. Preferred polyethylene polyamines include ethyienediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethylene-heptamine and mixtures and isomers thereof Suitably the polyisobutene substituent of the polyisobutene-substituted succinic acid or succinic anhydride has a number average moiecuiar weight of between 500 and 2000, preferably between 500 and 1500, more preferably between 500 and 1100, suitably between 600 and 1000, preferably between 700 and 800, for example about 750.

Component (i) may comprise a mixture of two or more acylated nitrogen compounds.

In the additive used in the present invention preferably at least 50 wt % of the additive has a number average molecular weight of more than 400, preferably at least 70% of the molecules, more preferably at least 90%, preferably at ieast 95%, suitably at least 97%.

A suitable method of measuring the molecular weight distribution of the additive is GPC using polystyrene standards.

The skilled person will appreciate that polyisobutene-substituted succinimide detergent additives typically contain a complex mixture of compounds. Such compounds are usually prepared by reacting polyisobutene (PIB) with maleic anhydride (MA) to form a polyisobutene- substituted succinic anhydride (PIBSA), which is then reacted with the polyamine (PAM) to form a polyisobutene-substituted succinimide (PIBSI). In the reaction of the PIB and MA more than one MA can react with each PIB and some unreacted PIB may remain. Each PIBSA molecule can react with one or more PAM molecule as described above. Varying the ratios of the different starting materials and including intermediate purification steps can affect the ratio of the various component of the final additive materiai. Some preferred phenylenediamine antioxidants (ii) suitable for use in the present invention include those of formula: wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ^K and R ⁷ are independently selected from hydrogen, an optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl group, an ester, a carboxylic acid, an aldehyde, a ketone, an ether, an alcohol, an amine or an amide. Preferably R ¹ is hydrogen. Preferably R ³ is hydrogen. Preferably R ² is an alkyl group, preferably having 1 -10 carbon atoms. More preferably R ² is an alkyl group having 1 -5 carbon atoms. Preferably R ² is selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secbutyl and tertiarybutyl. Most preferably R ² is isopropyl or secbutyl. Preferably R ⁴ is an alkyl group, preferably having 1 -10 carbon atoms. More preferably R ⁴ is an alkyl group having 1 -5 carbon atoms. R ⁴ is preferably selected from methyl, ethyl, propyl, isopropyl, secbutyl, butyl, tertiarybutyl and isobutyl. Most preferably R ⁴ is isopropyl or sec butyl.

R ⁵ , R ^s and R ⁷ are preferably selected from hydrogen or alkyl groups, more preferably from hydrogen and alkyl groups having 1-10 carbon atoms, more preferably from hydrogen and alkyl groups having 1-5 carbon atoms. Preferably R ⁶ , R ⁶ and R ⁷ are independently selected from hydrogen, methyl, ethyl, propyl, isopropyl, butyl, tertiarybutyl and isobutyl. Most preferably R ⁵ is hydrogen. Most preferably R ⁶ is hydrogen. Most preferably R ⁷ is hydrogen.

In especially preferred embodiments each of R ¹ , R ² , R ^;i , R ⁴ , R ⁵ , R ⁶ and R ⁷ is hydrogen and component (ii) comprises p-phenylene diamine.

Component (ii) may comprise a mixture of compounds and/or a mixture of isomers.

Preferred substituted hydroxylamine compounds (iii) for use herein are compounds of formula RaNOH in which each R is independently hydrogen or an optionally substituted hydrocarbyi group. Preferably each R is an optionally substituted hydrocarbyi group. Each R may be the same or different. Preferably each R is the same

Preferably each R is an optionally substituted alkyl or alkenyl group, preferably having from 1 to 12 carbon atoms, suitably 1 to 10 or 1 to 8 carbon atoms, for example 1 to 6, preferably from 1 to 4 carbon atoms. Preferably each R is an alkyl group. Each R may be a substituted alkyl group, for example a hydroxy substituted alkyl group Preferably each R is an unsubstituted alkyl group or a hydroxy alkyl group. More preferably each R is an unsubstituted alkyl group. The alkyl chain may be straight-chained or branched. Preferably each R is selected from methyl, ethyl, propyl and butyl, including isomers thereof. Most preferably each R is ethyl.

Preferably component (iii) comprises diethyfhydroxylamine.

Component (iii) may comprise a mixture of compounds and/or a mixture of isomers.

The composition of the first aspect of the present invention comprises a pyrolysis oil and (a) one or more nitrogen containing antioxidants. The nitrogen containing additives are preferably selected from (i) acylated nitrogen compounds, (ii) phenylenediamines and (ill) substituted hydroxyfamines.

In some embodiments component (a) of the composition of the first aspect includes (i) acylated nitrogen compounds.

In some embodiments component (a) of the composition of the first aspect includes (ii) phenylenediamines.

In some embodiments component (a) of the composition of the first aspect includes (iii) substituted hydroxylamines.

In some embodiments component (a) of the composition of the first aspect includes (i) acylated nitrogen compounds and (ii) phenylenediamines.

In some embodiments component (a) of the composition of the first aspect includes (i) acylated nitrogen compounds and (iii) substituted hydroxylamines.

In some embodiments component (a) of the composition of the first aspect includes (ii) phenylenediamines and (iii) substituted hydroxylamines.

In some embodiments component (a) of the composition of the first aspect includes (i) acylated nitrogen compounds, (ii) phenylenediamines and (iii) substituted hydroxylamines.

In some embodiments the composition of the first aspect may further comprise (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units. The copolymer (b) is suitably an alternating copolymer and is prepared by reacting maleic anhydride with an a-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 US4151069.

The copolymer additive of the invention is suitably prepared by reacting maleic anhydride with an a-olefin in a molar ratio of from 3:1 to 1 :3, preferably 2:1 to 1 :2, more preferably from 1.5:1 to 1 :1 .5, for example about 1 :1.

Preferably the a-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 a-olefin has from 18 to 30 carbon atoms, for example from 20 to 28 carbon atoms.

To form the copolymer additive of the invention a mixture of a-olefins may be used.

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

In one embodiment a mixture of a-olefins having 24 to 28 carbon atoms is used, for example a mixture having 26 to 28 carbon atoms.

The present invention relates to a copolymer comprising maleic anhydride derived units and a- olefin derived units.

The copolymer directly obtained from the reaction of an a-olefin and maleic anhydride comprises alkyl chains and anhydride functional groups.

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

In some embodiments the anhydride and/or hydrolysed acid product may be partially or fully further functionalised, for example by reaction with amines and/or alcohols to incorporate ester and/or amide and/or imide functional groups into the copolymer

In preferred embodiments the copolymer is not further functionalised in this way and the maleic anhydride derived units are present as underivatized 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 a-olefin with maleic anhydride.

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

Preferably the copolymer has a number average molecular weight of from 5000 to 20000 Da, in one embodiment the copolymer has a number average molecular weight of from 5000 to 10000 Da. In one embodiment the copolymer has a number average molecular weight of from 8000 to 17000 Da.

In some embodiments the composition of the first aspect may further comprise (c) the reaction product of a carboxylic acid and a polyamine.

Preferably the carboxylic acid and the polyamine react to form a hetrocyclic moiety, for example an imidazoline or a tetrahydropyridlmine moiety. Preferably the polyamine includes an optionally substituted ethylene diamine moiety and the reaction product with a carboxylic acid leads to an imidazoline.

Preferably the reaction product of component (c) is a substituted imidazoline compound. Such compounds are known in the art of fuel and lubricant additives.

Preferred compounds are formed by the reaction of fatty acids and polyamines and suitable compounds of this type are described, for example, in USRE23227, US3193454 and US7857871 .

Suitable polyamines include hydroxy-substituted polyamines, for example as described in US2007193110.

Suitable acids which can be used to prepare the additives of component (c) include ethercarboxylic acids (for example as described in US6372918) and terpine derived carboxylic acids (for example as described in US4994575).

In some embodiments component (c) may include imidazolines which have been further reacted This further reaction may be with alkylene oxides (for example see US2713582), arylsulfonic acids (for example see US4247300A) or sulfonating agents such as SCh (for example see US2917376). Preferably component (c) comprises the reaction product of one or more fatty acids having 10 to 36 carbon atoms and a polyethylene polyamine having from 2 to 8 nitrogen atoms.

Preferred fatty acids are compounds of formula RCOOH in which R is an alkyl or alkenyl group having 10 to 36 carbon atoms, preferably 12 to 30 carbon atoms, more preferably 12 to 24 carbon atoms, suitably 14 to 22 carbon atoms, more preferably 16 to 20 carbon atoms.

The fatty acid may be a naturally occurring fatty acid comprising a mixture of compounds. Preferably the fatty acid includes a C18 component

A preferred fatty acid is tail oil fatty acid.

Suitable polyethylene polyamines for reacting with the fatty acid include ethylenediamine, diethyienetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethylene-heptamine and mixtures and isomers thereof,

Most preferably component (c) comprises an imidazoline containing reaction product of tall oil fatty acid and diethylene triamine.

In some embodiments the composition of the first aspect comprises (d) a metal deactivator compound.

In some embodiments the diesel fuel composition used in the present invention further comprises a metal deactivating compound. Any metal deactivating compound known to those skilled in the art may be used and include, for example, the substituted triazole compounds of figure (A) wherein R and R’ are independently selected from an optionally substituted alkyl group or hydrogen. Preferred metal deactivating compounds are those of formula (B): wherein R ¹ , R ² and R ³ are independently selected from an optionally-substituted alkyl group or hydrogen, preferably an alkyl group from 1 to 4 carbon atoms or hydrogen. R ¹ is preferably hydrogen, R ² is preferably hydrogen and R ³ is preferably methyl, n is an integer from 0 to 5, most preferably 1 .

A particularly preferred metal deactivator is N,N’- disalicyclidene-1 ,2-diaminopropane, and has the formula shown in figure (C);

Another preferred metal deactivating compound is shown in figure (D):

Components (a), (b) and (c) are suitably included in the compositions of the first aspect in an amount based on the proportion of pyrolysis oil present in the composition. By this we mean that for a blended fuel, the treat rate of the additive is adjusted to take account of the amount of pyrolysis oil present in a blend. Thus if a component would be added to a neat pyrolysis oil in an amount of 500 ppm, a treat rate of 250 ppm would be used for a blended fuel comprising 50% pyrolysis oil.

The nitrogen containing antioxidant component (a) is preferably included in the composition of the first aspect in an amount of at least 10 ppm, preferably at least 20 ppm, more preferably at least 50 ppm, for example at least 70 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

The nitrogen containing antioxidant component (a) may be included in the composition of the first aspect in an amount of up to 10000 ppm, preferably up to 5000 ppm, more preferably up to 2000 ppm for example up to 1000 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

Preferably the nitrogen containing antioxidant component (a) is present in the composition of the first aspect in an amount of from 1 to 10000 ppm, preferably 10 to 1000 ppm, preferably 50 to 750 ppm, more preferably 100 to 500 ppm, for example 150 to 400 ppm or 200 to 350 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

In some embodiments, the nitrogen containing antioxidant component (a) is present in the composition of the first aspect in an amount of from 10 to 500 ppm, preferably 20 to 300 ppm, 50 to 200 ppm or 50 to 175 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

In preferred embodiments component (a) comprises a mixture of (i) acylated nitrogen compounds, (ii) phenylenediamines and (iii) substituted hydroxylamines. These are suitably present in a ratio of 1 to 4 parts (i): 1 to 4 parts (ii): 2 to 6 parts (iii) by weight.

In preferred embodiments the composition of the first aspect comprises from 1 to 250 ppm, preferably from 10 to 150 ppm, for example from 50 to 100 ppm of (i) acylated nitrogen compounds; from 1 to 250 ppm, preferably from 10 to 150 ppm, for example from 50 to 100 ppm of (ii) phenylenediamines; and optionally from 1 to 500 ppm, preferably from 50 to 250 ppm, for example from 100 to 150 ppm of (iii) substituted hydroxyfamines, based in each case on the proportion of pyrolysis oil present in the composition.

Copolymer component (b), when present, is preferably included in the composition of the first aspect in an amount of at least 10 ppm, preferably at least 20 ppm, more preferably at least 40 ppm, for example at least 50 ppm, based in each case on the proportion of pyrolysis oil present in the composition. Copolymer component (b), when present, may be included in the composition of the first aspect in an amount of up to 10000 ppm, preferably up to 5000 ppm, more preferably up to 1000 ppm, for example up to 500 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

Preferably the copolymer component (b), when present, is included in the composition of the first aspect in an amount of from 1 to 5000 ppm, preferably 5 to 1000 ppm, preferably 10 to 500 ppm, more preferably 20 to 300 ppm, for example 30 to 200 ppm or 50 to 150 ppm, based in each case on the proportion of pyrolysis oil present in the composition

Component (c), when present, is preferably included in the composition of the first aspect in an amount of at least 10 ppm, preferably at least 20 ppm, more preferably at least 40 ppm, for example at least 50 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

Component (c), when present, may be included in the composition of the first aspect in an amount of up to 10000 ppm, preferably up to 5000 ppm, more preferably up to 1000 ppm, for example up to 500 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

Preferably component (c), when present, is included in the composition of the first aspect in an amount of from 1 to 5000 ppm, preferably 5 to 1000 ppm, preferably 10 to 500 ppm, more preferably 20 to 300 ppm, for example 30 to 200 ppm or 50 to 150 ppm, based in each case on the proportion of pyrolysis oil present in the composition.

The metal deactlvator (d) may be optionally included in the composition in an amount of from 1 to 1000 ppm, preferably 5 to 500 ppm, for example 10 to 100 ppm.

In this specification any reference to ppm is to parts per million by weight.

In preferred embodiments, the first aspect of the present invention provides a composition comprising: a pyrolysis oil; from 100 to 500 ppm, preferably from 200 to 400 ppm of (a) one or more nitrogen containing antioxidants; and optionally from 10 to 400 ppm, preferably from 50 to 200 ppm of: (b) a copolymer comprising maleic anhydride derived units and o-olefin derived units and/or (c) the reaction product of a carboxylic acid and a polyamine.

In some embodiments the composition of the first aspect may be used as a middle distillate fuel oil. Thus the composition may include one or more further additives such as those which are commonly found in diesel fuels. These include, for example, antioxidants, dispersants, detergents, metal deactivating compounds, wax anti-settling agents, cold flow improvers, cetane improvers, dehazers, stabilisers, demulsifiers, antifoams, corrosion inhibitors, lubricity improvers, dyes, markers, combustion improvers, metal deactivators, odour masks, drag reducers and conductivity improvers. Examples of suitable amounts of each of these types of additives will be known to the person skilled in the art.

According to a second aspect of the present invention there is provided an additive composition for a pyrolysis oil comprising:

(a) one or more nitrogen containing antioxidants; and optionally:

(b) a copolymer comprising maleic anhydride derived units and a-olefin derived units: and/or

(c) the reaction product of a carboxylic acid and a polyamine.

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

Preferably the additive composition comprises a diluent or solvent Suitable diluents and solvents will be known to the person skilled in the art.

Preferred solvents include mixtures of aromatic solvents, for example xylene, aromatic 150 or aromatic 100.

In one especially preferred embodiment the additive composition of second aspect comprises:

(a) nitrogen containing antioxidants including (i) acylated nitrogen compounds, (ii) phenylenediamines and (ill) substituted hydroxylamines;

(b) a copolymer comprising maleic anhydride derived units and a-olefin derived units; and/or

(c) the reaction product of a carboxylic acid and a polyamine; and an aromatic solvent.

The use of additive component (a), optionally in combination with additives (b) and/or (c), has been found to improve the oxidation stability of pyrolysis oils.

There are a number of standard tests available for assessing the stability of diesel fuel, including ASTM D4625, ASTM D6468 and ASTM D2274.

The present inventors have measured the oxidation stability of the compositions of the present invention using the Rancimat test. This test is commonly used to assess the oxidation stability of biodiesel compositions. Like pyrolysis oils biodiesei comprises high levels of components which can be easily oxidised by atmospheric oxidation.

The Rancimat test is an accelerated oxidation test in which a sample is heated with air bubbling through. Volatile breakdown products pass over into deionised water and the conductivity of the water is measured. The time taken for fuel to breakdown is measured by recording the time at which an increase in conductivity is observed. This is known as the induction period.

To assess the oxidation stability of the pyrolysis oil compositions of the present invention the inventors followed the Rancimat test method set out in European standard EN 14112, the only difference being the nature of the fuel.

The use of additive component (a), optionally in combination with additives (b) and/or (c), has been found to improve the storage stability of pyrolysis oils. The storage stability of oils may be assessed using standard tests, such as ASTM D4625.

According to a third aspect of the present invention, there is provided a method of improving the oxidation stability of a composition comprising a pyrolysis oil, the method comprising adding to the composition (a) one or more nitrogen containing antioxidants.

The method may optionally further comprise adding to the composition:

(b) a copolymer comprising maleic anhydride derived units and a-olefin derived units; and/or

(c) the reaction product of a carboxylic acid and a polyamine.

According to a fourth aspect of the present invention, there is provided the use of (a) one or more nitrogen-containing antioxidants to improve the oxidation stability of a composition containing a pyrolysis oil.

The fourth aspect of the present invention may involve the use of (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units; and/or (c) the reaction product of a carboxylic acid and a polyamine in combination with (a) one or more nitrogen-containing antioxidants to improve the oxidation stability of a composition containing a pyrolysis oil.

Preferred features of the third and fourth aspects, including the nature of the composition, and the nature of components (a), (b) and (c) and suitable treat rates thereof, are as defined in relation to the first aspect. The method and use of the present invention suitably increase the oxidation stability of a composition comprising a pyrolysis oil as measured by the Rancimat test.

Preferably the use of (a) a nitrogen-containing dispersant increases the induction time as measured by the Rancimat test of a composition containing a pyrolysis oil by at least 50%, preferably at least 100%, more preferably at least 150%, for example at least 200% or at least 300%.

The use of (a) a nitrogen-containing dispersant may increases the induction time as measured by the Rancimat test of a composition containing a pyrolysis oil by at least 2 hours, preferably at least 4 hours, suitably at least 6 hours.

In some embodiments the use of (a) a nitrogen-containing dispersant may increases the induction time as measured by the Rancimat test of a composition containing a pyrolysis oil by at least 8 hours, preferably at least 10 hours, suitably at least 12 hours

Suitably the use of (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units and/or (c) the reaction product of a carboxylic acid and a polyamine in combination with (a) one or more nitrogen-containing antioxidants increases the oxidation induction time as measured by the Rancimat test of a composition comprising a pyrolysis oil by at least 50%, preferably at least 100%, more preferably at least 150%, for example at least 200% or at least 300% .

Suitably the use of (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units and/or (c) the reaction product of a carboxylic acid and a polyamine in combination with (a) one or more nitrogen-containing antioxidants increases the oxidation induction time as measured by the Rancimat test of a composition comprising a pyrolysis oil by at least 2 hours, preferably at least 4 hours, suitably at least 6 hours.

In some embodiments use of (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units and/or (c) the reaction product of a carboxylic acid and a polyamine in combination with (a) one or more nitrogen-containing antioxidants increases the oxidation induction time as measured by the Rancimat test of a composition comprising a pyrolysis oil by more than 8 hours, for example more than 10 hours or more than 12 hours.

In a fifth aspect the present invention provides a method of improving the oxidation stability of a composition comprising a pyrolysis oil and one or more nitrogen containing antioxidants, the method comprising adding to the composition: (b) a copolymer comprising maieic anhydride derived units and a-olefin derived units; and/or

(c) the reaction product of a carboxylic acid and a pofyamine.

In a sixth aspect the present invention provides use of (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units and/or (c) the reaction product of a carboxylic acid and a pofyamine to improve the oxidation stability of a composition comprising a pyrolysis oil and one or more nitrogen containing antioxidants.

Preferred features of the fifth and sixth aspects, including the nature of the composition, and the nature of components (a), (b) and (c) and suitable treat rates thereof, are as defined in relation to the first aspect.

According to a seventh aspect of the present invention, there is provided a method of improving the storage stability of a composition comprising a pyrolysis oil, the method comprising adding to the composition (a) one or more nitrogen containing antioxidants.

The method may optionally further comprise adding to the composition:

(b) a copolymer comprising maleic anhydride derived units and a-olefin derived units; and/or

(c) the reaction product of a carboxylic acid and a polyamine.

According to an eighth aspect of the present invention, there is provided the use of (a) one or more nitrogen-containing antioxidants to improve the storage stability of a composition containing a pyrolysis oil.

This eighth aspect of the invention may involve the use of (b) a copolymer comprising maleic anhydride derived units and a-olefin derived units; and/or (c) the reaction product of a carboxylic acid and a polyamine in combination with (a) one or more nitrogen-containing antioxidants to improve the storage stability of a composition containing a pyrolysis oil.

In a ninth aspect the present invention provides a method of improving the storage stability of a composition comprising a pyrolysis oil and one or more nitrogen containing antioxidants, the method comprising adding to the composition:

(b) a copolymer comprising maleic anhydride derived units and a-olefin derived units; and/or

(c) the reaction product of a carboxylic acid and a poiyamine. In a tenth aspect the present invention provides use of (b) a copoiymer comprising maieic anhydride derived units and a-olefin derived units and/or (c) the reaction product of a carboxylic acid and a polyamine to improve the storage stability of a composition comprising a pyrolysis oil and one or more nitrogen containing antioxidants.

The methods and uses of the seventh, eighth, ninth and tenth aspects of the present invention suitably improves the storage stability of a composition comprising a pyrolysis oil as measured by the standard method of ASTM D4625 and/or by said standard method as modified to be conducted at ambient temperature using 200 ml samples of the pyrolysis oil. Said improvement in storage stability suitably results in / is provided by a reduction in the amount of adherent insoluble material produced by the pyrolysis oii on storage, compared to a comparable unadditised pyrolysis oil, and/or a reduction in the total amount of insoluble material produced by the pyrolysis oil on storage, suitably as measured by the methods referred to above.

In some embodiments, the methods and uses of the seventh, eighth, ninth and tenth aspects provide at least a 30% reduction in the amount of adherent insoluble material produced by the pyrolysis oii on storage, compared to a comparable unadditised pyrolysis oil, suitably at least a 70% reduction, at least an 80% reduction or at least a 90% reduction in said amount of adherent insoluble material, suitably as measured by ASTM D4625 and/or by said standard method modified as described herein.

In some embodiments, the methods and uses of the seventh, eighth, ninth and tenth aspects provide at least a 30% reduction in the amount of total insoluble materia! produced by the pyrolysis oil on storage, compared to a comparable unadditised pyrolysis oii, suitably at least a 40% reduction, at least a 50% reduction or at least a 60% reduction in said amount of total insoluble material, suitably as measured by ASTM D4625 and/or by said standard method modified as described herein.

Preferred features of the seventh, eighth, ninth and tenth aspects, including the nature of the composition, and the nature of components (a), (b) and (c) and suitable treat rates thereof, are as defined in relation to the first aspect.

Any feature of any aspect of the invention may be combined with any other aspect, as appropriate.

The invention will now be further described by way of the following non-iimiting examples Example 1

Additive compositions comprising the following components were prepared:

Table 1

PIBSI A is polyisobutenyl succinimide obtained from the condensation reaction of a polyisobutenyf succinic anhydride derived from polyisobutene of Mn approximately 750 with a polyethylene polyamine mixture of average composition approximating to tetraethylene pentaamine.

Metal deactivator B is N,N'- disalicyclidene-1 ,2-diaminopropane.

Copolymer C an alternating copolymer of maleic anhydride and a mixture of a-olefins having 20 to 24 carbon atoms. The number average molecular weight is 15000 Da.

Imidazoline D is the reaction product of diethyiene triamine and tall oil fatty acid,

Example 2

Compositions 1 , 2 and 3 from example 1 were dosed into a waste rubber (waste tyre) pyrolysis oil having the following specification; Table 2 The induction period of the base waste rubber pyrolysis oil was measured using the method set out in EN 14112 500 ppm of compositions 1 , 2 and 3 were separately dosed into three further samples of the waste rubber pyrolysis oil and the Rancimat test was repeated.

The results are shown in table 3:

Table 3

Example 2

Additive compositions 1 , 2 and 3 from Example 1 were dosed at 500 mg/l into the waste tyre pyrolysis oil having the specification described above to provide oil pyrolysis oii compositions 1, 2 and 3, respectively. These samples were tested for storage stability against an unadditised sample of the waste rubber pyrolysis oii, using a modification of the standard method of ASTM D4625. The standard method was modified by conducting the tests at ambient temperature instead of 43°C and by using 200 ml samples of the pyrolysis oils instead of 400 ml samples. The method provides amounts of filterable insoluble material, adherent insoluble material and total insoluble material in each sample.

The amounts of insoluble material recovered (filterable and adherent) for each composition, including the total amounts, are shown in Table 4:

Table 4 These results show a significant reduction in the amount of adherent insoluble material produced by the plastic pyrolysis oil on storage when the additives of the present invention are used. The results for samples 1 , 2 and 3 (at 500 mg/l treat rate) also show a significant reduction in the total amount of insoluble material produced on storage. These additives may therefore be effective in improving the storage stability of a pyrolysis oil.