BR112014022491B1 - use of a viscosity-improving additive - Google Patents

Abstract

USE OF A VISCOSITY IMPROVEMENT ADDITIVE. Use of a viscosity-enhancing additive in a diesel fuel formulation for the purpose of increasing the compressibility of the formulation. The viscosity-enhancing additive can be selected from (i) olefin-based polymers (in particular styrene-based polymers); (ii) naphthenic, paraffinic or synthetic base oils; (iii) polymethacrylates; and (iv) mixtures thereof. It can be used to increase the isothermal compressibility of the diesel fuel formulation at typical fuel injection pressures and temperatures and, in turn, to improve the performance related to the power of a compression ignition engine, operating under the fuel formulation.

Description

Field of the Invention

[0001] This invention relates to the use of certain types of additives, in diesel fuel formulations, for new purposes.

Fundamentals of the Invention

[0002] It is often desired to improve the performance of internal combustion engines, through the use of modified fuels. In the past, for example, diesel fuels have been modified by the addition of relatively high density components in order to improve the performance related to the power of engines operating on fuels. In modern direct injection diesel engines, a higher density fuel will typically lead to an increase in the mass of the combustible material that is supplied inside the combustion chamber through fixed-volume fuel injectors in the engine; this, in turn, increases the energy made available through the combustion process.

[0003] It is not honest to predict how a fuel will behave in an engine's injection system, particularly under the extremely high injection pressures (often in excess of 200 MPa (2000 bar)) to which it will be subjected in a modern diesel engine. A diesel fuel is a complex mixture of hydrocarbons of different molecular weights and not all of these molecules will respond in the same way to pressure increases. In addition, the geometry of the injection system can itself affect the way in which fuel viscosity and other properties will impact engine performance.

[0004] It is an objective of the present invention to provide an alternative way to improve the performance of the engine by modifying the properties of diesel fuels, in particular through the use of fuel-compatible additives.

Declarations of the Invention

[0005] According to a first aspect of the present invention, the use of a viscosity-enhancing additive in a diesel fuel formulation is provided for the purpose of increasing the compressibility of the formulation.

[0006] The present invention is based on the realization that it is possible to use additives to modify the compressibility of a diesel fuel formulation, that is, the rate at which its density changes with increasing pressure. An increase in the compressibility of a fuel means that when it is subjected to increasing pressures, such as within a fuel injection system, its density will increase at a higher rate. This in turn means that, at any given injection pressure, the fuel will have a higher density. Thus, at the high pressures experienced in the injection system of a diesel engine (typically from 160 (1600) to 250 MPa (2500 bar), the fuel will provide a higher energy content in each injection event. it can increase the power supply through the engine and, consequently, its performance.

[0007] It has been surprisingly found that viscosity-improving additives can, in addition to increasing the viscosity of a diesel fuel formulation, at any given temperature and pressure, also increase its compressibility. In addition, this effect appears to be particularly marked at high pressures (for example, excess of 150 (1500) or even 200 MPa (2000 bar)) and high temperatures (for example, excess of 100 ° C, often up to 250 ° C , which are typically used in modern diesel engines.

[0008] Thus, at typical injection pressures and temperatures, a diesel fuel formulation for use according to the present invention will have a higher density than in the absence of the viscosity-improving additive. This can produce an increase in the power supplied by an engine operating in the formulation. According to the invention, therefore, a quality improvement additive can be used to improve the performance related to the strength of an engine running in a diesel fuel formulation, increasing the compressibility of the formulation. Although the additive cannot increase the density of the formulation to a great degree under standard measurement conditions (for example, at atmospheric pressure and 15 or 40 ° C), it can increase the density to a considerably greater degree under injection conditions.

[0009] The invention is expected to have particular benefits in modern diesel engines, as the rail pressures used in such engines are continually increasing. A fuel formulation that is capable of responding to increasing pressure with an increase in energy output and strength, may represent a promising candidate for use in high-performance engines and the vehicles they power.

[00010] The viscosity-enhancing additive used in the present invention can be any component, or mixture of them, that is suitable for use in a diesel fuel formulation and that, when added to such formulation, causes an increase in its viscosity, in particularly its kinematic viscosity. A range of such components is known and commercially available.

[00011] Viscosity enhancers have been used in diesel fuels in the past. WO-A-2005/054411, for example, describes the use of a viscosity-increasing component in a diesel fuel composition, for the purpose of improving vehicle handling effort (VTE) and / or the acceleration performance of a diesel engine into which the composition is introduced. Components used to increase the viscosity of the fuel composition include hydrocarbon diesel fuel components, such as, in particular, diesel components derived from Fischer-Tropsch, and oils, which can be of mineral or synthetic origin and can also be derived from Fischer-Tropsch. Tropsch. US-A-2009/0241882 describes the use of a viscosity index (VI) enhancement additive in an automotive diesel fuel composition for the purpose of improving the acceleration performance of an engine within which the fuel composition is introduced or a vehicle powered by such an engine.

[00012] However, such descriptions have failed to establish, or even investigate, a link between the viscosity of a fuel formulation and its compressibility, in particular at typical fuel injection pressures. Such a bond is not necessarily predictable, due to the relatively complex constitutions and properties of fuel formulations. It could not have been predicted by this previous work that viscosity-enhancing additives would have an effect on fuel compressibility, even at high temperatures and pressures. Previous work on the densities and viscosities of additive fuels has focused mainly on fuel properties, measured at ambient temperature and pressure, as in many of the standard test methods (eg ASTM), rather than investigating behavior changes in fuel under injection conditions.

[00013] Magin et al. in Energy & Fuels, vol. 26, no. 2, pages 1336 to 1343 in a document entitled 'Bulk Modulus of Compressibility of Diesel / Biodiesel / HVO' will find a synergistic effect resulting in higher values for the density module for HVO / Diesel mixtures that have reached a maximum for an HVO content of 25%. The document speculates that the reason for this effect is the increase in the diversity of hydrocarbon structures, provided by incorporating HVO in diesel and that, similarly where small amounts of HVO are used in fuel mixtures, the resulting decrease in structure diversity molecular yields significant decreases in the compressibility module.

[00014] According to the invention, the viscosity improving additive can be an oligomeric or polymeric component, in particular a polymeric one. It can be selected from: i. olefin-based polymers; ii. naphthenic, paraffinic or synthetic base oils; iii. polymethacrylates; and iv. mixtures thereof.

[00015] It has been found that olefin-based polymers can produce a useful increase in compressibility in only a fraction of the amount of additive than a base oil additive.

[00016] An additive of type (i) is therefore especially preferred. It is a polymer that comprises one or more olefinic monomer units. In the context of the present invention, the term "polymer" includes a copolymer. An additive of type (i) can be a copolymer, in particular a block copolymer, which can comprise a mixture of two or more olefinic monomer units. The olefinic monomeric units can, for example, be selected from ethylene, propylene, butylene, butadiene, isoprene and styrene.

[00017] An additive of type (i) can be selected from polyisobutylene (PIBs), poly-alpha olefins (PAOs), ethylene-propylene copolymers (including both semicrystalline and amorphous copolymers), styrene-based polymers and mixtures thereof. It can be selected from ethylene-propylene copolymers, styrene-based polymers and mixtures thereof.

[00018] Suitable ethylene-propylene copolymers are available, for example, as additives LZ 706X (from Lubrizol). Adequate PIBs are commercially available, for example, as Indopol-H (from INEOS). Suitable PAOs are commercially available, for example, as Durasyn® (from INEOS) or Synfluid® (from Chevron Phillips).

[00019] In one embodiment, the additive of type (i) comprises a polymer based on styrene, i.e., a polymer or copolymer that comprises one or more styrenic monomer units. It can comprise a styrene-based copolymer, for example, a copolymer of at least one styrenic monomer with at least one olefinic monomer. Such suitable polymers are available, for example, as Kraton ™ D or Kraton ™ G additives (from Kraton) or as SV ™ additives (from Infineum, Multisol and others). They have been used in the past as viscosity enhancing additives and viscosity index enhancers, including in diesel fuel formulations: see, for example, US-A- 2009/0241881. They were also used as additives in lubricants (see WO-A-2008/024111).

[00020] The additive of type (i) can in particular be selected from copolymers of styrenic and olefinic monomers (in particular copolymers of styrene monomers with ethylene, propylene, butylene, butadiene and / or isoprene monomers (2-methyl -1, 3-butadiene)) and mixtures thereof. It can, for example, be selected from polystyrene-polyisoprene copolymers, polystyrene-polybutadiene copolymers and mixtures thereof. Such copolymers can be block copolymers, such as SV ™ 150 (a linear polystyrene-polyisoprene diblock copolymer) or Krton ™ additives (styrene-butadiene-styrene triblock copolymers or styrene-ethylene-butylene triblock copolymers). They can be tapered copolymers, for example, styrene-butadiene copolymers. They can be star copolymers, such as SV ™ and SV ™ 260 and SV ™ 200 (which are polystyrene-polyisoprene star copolymers).

[00021] In one embodiment, additive (i) is selected from polystyrene-polyisoprene copolymers and mixtures thereof. In one embodiment, it is selected from SV ™ additives and mixtures thereof, for example, from SV ™ 150, SV ™ 200, SV ™ 260 and mixtures thereof. In one embodiment, it is selected from SV ™ 150, SV ™ 260 and mixtures thereof. In one embodiment, it comprises SV ™ 150.

[00022] An additive of type (ii) is more suitably derived from naphthenic base oil derived from crude naphthenic oils. It can in particular be a mineral oil or a mixture thereof, for example, a naphthenic mineral based oil. The base oil, or a component thereof, can be a synthetic product, such as a component derived from Fischer-Tropsch.

[00023] A base oil (ii) can, for example, be a Group III, Group IV or Group V base oil. In one embodiment, it is a Group V API (American Petroleum Institute base oil) ). Group V base oils include synthetic non-PAO components, such as diesters, polyolesters, and alkylated hydrocarbons, such as alkylated naphthenes and alkylated benzenes.

[00024] In a specific embodiment, a base oil (ii) can have a density at 15 ° C of 875 to 885 kg / m3 (DIN RI 757 D; ISO 12185), for example, about 880 kg / m3. It can have a kinematic viscosity at 40 ° C (VK 40) of 7.7 to 8.2 mm2 / s (DIN 51 562, T.l; ISO 3104), for example, about 7.9 mm2 / s; and / or a kinematic viscosity at 100 ° C (VK 100) of about 2.1 mm2 / s (ISO 3104). It can have a vapor pressure at 20 ° C of less than 0.01 kPa; a pouring point of -60 ° C (DIN ISO 3016); a flash point of 146 ° C (ISO 2719); and / or a polycyclic aromatic compound (PCA) content of about 1% w / w (IP 346).

[00025] Base oils, in particular particular mineral base oils, are widely available, for example, in the Shell group of companies. They have been used in the past to increase the viscosity and density of diesel racing fuels.

[00026] In one embodiment, the type (ii) additive comprises the lubricating oil base HNR40D, which is a naphthenic mineral oil, available from the Shell group of companies.

[00027] Type (iii) additives are available, for example, as Viscoplex ™ 1-300 (from Evonik), which is used as a tipping point depressant and as a lubricant viscosity modifier.

[00028] In an embodiment of the invention, the viscosity-enhancing additive is selected from olefin-based polymers; base oils; and mixtures thereof. In one embodiment, it is selected from polymers based on styrene; base oils; and mixtures thereof. In one embodiment, it comprises a polymer based on styrene or a mixture thereof.

[00029] An additive of type (i) to (iv) can be used, according to the invention, in the form of an additive composition that contains both the active ingredient (for example, an olefin-based polymer) and a carrier fluid appropriate. Carrier fluids (in particular carrier solvents) include, for example, mineral oils, aromatic hydrocarbon solvents, such as Shellsol ™ Al50 (from Shell), other hydrocarbons and hydrocarbon mixtures with boiling points within the normal boiling range diesel, alkyl fatty acid esters (in particular fatty acid methyl esters) and mixtures thereof.

[00030] Such an additive composition may comprise one or more additional active substances, for example, selected from substances that are active such as detergents, de-creams, anti-corrosion additives, anti-foam additives, lubricity improvers, cold flow improvers, cetane improvers and mixtures of them, in particular of substances that are active such as detergents, detergents, anti-corrosion additives, anti-foam additives and mixtures thereof.

[00031] In one embodiment, the viscosity-improving additive is a viscosity-indexing additive, that is, a component that, when added to a diesel fuel formulation, causes an increase in its viscosity index VI . The VI of a fuel formulation is a measure of the rate of change of the formulation's viscosity with temperature. A fuel formulation with a relatively high VI will exhibit a lower reduction in its viscosity than a fuel formulation with a relatively low VI, through any given increase in temperature.

[00032] Viscosity index enhancing additives (also referred to as VI enhancers) are already known in lubricant formulations, where they are used to maintain viscosity as constant as possible, over a desired temperature range, increasing viscosity at higher temperatures. They are typically based on relatively high molecular weight, long chain polymeric molecules, which can form conglomerates and / or mycelia. These molecular systems expand at higher temperatures, thus further restricting their movement in relation to each other and, in turn, increasing the viscosity of the system.

[00033] Known IV enhancers include polymethacrylates (PMAs), polyisobutylene (PIBs), ethylene-propylene copolymers and other olefin copolymers (OCPs) and styrene / olefin copolymers, such as those mentioned above. Thus, many of the viscosity-enhancing additives (1) and (iii) are also capable of acting as VI-enhancing additives in diesel fuel formulations.

[00034] In WO-A-01/48120, certain of these types of additives are proposed for use in diesel fuel compositions, for the purpose of improving the ability of an engine to start at high temperatures. They were not, however, to our knowledge, proposed for use in increasing the compressibility of a diesel fuel formulation.

[00035] According to the invention, the viscosity-enhancing additive can be used in the formulation of diesel fuel in a (active substance) concentration of 0.01% w / w or greater, or 0.05% w / w or greater, or 0.1% w / w or greater. In some cases it can be used in a (active substance) concentration of 0.5 or 1% w / w or greater. It can be used in a (active substance) concentration of up to 30% w / w, or up to 25 or 20 or 15% w / w or, more appropriately, up to 10% w / w or up to 7.5 or 5 or 2.5% w / w. In some cases it can be used in a (active substance) concentration of up to 1 or 0.5% w / w, such as 0.01 to 0.5% w / w or 0.05 to 0.5% p / p.

[00036] In a first specific embodiment, in particular when the viscosity-improving additive is of type (i) or (iii) and, more particularly, when it is an ethylene-propylene copolymer or styrene-based polymer, most particularly a styrene-based polymer, its (active substance) concentration in the diesel fuel formulation can be 0.01% w / w or greater, or 0.025 or 0.05% w / w or greater, or 0.1% w / w or greater. In this embodiment, the (active substance) concentration of the additive can be up to 0.5% w / w or up to 0.4 or 0.3 or 0.2% w / w, such as 0.01 to 0, 5% w / w or 0.04 to 0.02% w / w or 0.05 to 2% w / w. In preferred embodiments, an additive of type (i) is used in the formulation of diesel fuel at a concentration in the range of 0.01 to 2% w / w, more preferably from 0.01 to 1% w / w especially 0.01 to 0.5% w / w, for example, 0.01 to 0.2% w / w, or 0.04 to 0.2% w / w.

[00037] It is a significant advantage that the increase in compressibility can be provided by such viscosity-enhancing additives at such low concentrations that are typically associated with fuel additives. This is, for example, preferred in order to minimize the impact of the invention on fuel preparation and handling processes.

[00038] In a second specific embodiment, in particular when the viscosity improving additive is of type (ii), its concentration in the diesel fuel formulation can be 1% w / w or more, or 2% w / w w or more or in some cases 5 or 10% w / w or more. In this embodiment the concentration of the additives can be up to 30% w / w or up to 25 or 20 or 15% w / w, suitably up to 10% w / w or up to 7.5 or 5% w / w, such as 1 to 10% w / w or 1 to 5% w / w. Such viscosity-enhancing additives can thus be included in fuel formulations in concentrations typically associated with the components of the fuel. Ideally, in such a case, the additive will not be harmful to the properties of the global formulation, that is, the global formulation will still be in accordance with the relevant applicable standards, such as EN 590 or ASTM D975, even though it has higher density and compressibility under injection temperatures and pressures.

[00039] A diesel fuel formulation used in accordance with the present invention (i.e., a diesel fuel formulation in which a viscosity improving additive is or has been used according to the invention) may comprise, in addition to the additive improving viscosity, one or more components and / or diesel fuel additives, as they are known in the art. It may comprise, for example, a diesel fuel or a mixture thereof.

[00040] A diesel fuel can be any fuel component, or mixture thereof, that is suitable and / or adapted for use in a diesel fuel formulation and, therefore, for combustion within a compression ignition engine (diesel ). It will typically be a medium distilled liquid hydrocarbon fuel, more typically diesel. It can be derived from oil. It can be or contain a kerosene fuel component. Alternatively, it can be synthetic: for example, it can be the product of a Fischer-Tropsch condensation. It can be derived, directly or indirectly, from a biological source, such as plant biomass. It can be or include an oxygenate, such as an alkyl fatty acid ester, in particular a fatty acid methyl ester (FAME), such as rapeseed methyl ester or palm oil methyl ester.

[00041] A diesel fuel will typically boil in the range of 150 or 180 to 370 ° C (ASTM D86 or EN ISO 3405). It will suitably have a measured cetane number (ASTM D613) of 40 to 70 or 40 to 65 or 51 to 65 or 70. It will appropriately have a density of 750 to 900 kg / m3, or 800 to 860 kg / m3, or more suitably from 820 to 845 kg / m3, at 15 ° C (ASTM D4052 or EN ISO 3675) and / or a VK 40 of 1.5 to 6.0 mm2 / s or 2.0 to 4.5 mm2 / s (ASTM D445 or EN ISO 3104).

[00042] Where a fuel formulation used in accordance with the present invention comprises a diesel based fuel, the concentration of the formulation's base fuel can be 60% v / v or greater, or 65 or 70 or 75 or 80 or 85 or 90% v / v or greater or, in some cases 95% v / v or greater. Its concentration can be up to 99.99% v / v or up to 99.95 or 99.9% v / v, or up to 99.8 or 99.5% v / v, or up to 99 or 98 or 95% v / v. The base fuel can represent the main part of the fuel formulation: after adding the viscosity-enhancing additive and any other (optional) fuel components and additives, the diesel-based fuel can therefore represent the rest to 100%.

[00043] A diesel fuel formulation used in accordance with the present invention will properly comply with the current applicable standard diesel fuel specification (s), such as, for example, EN 590 (for Europe) or ASTM D975 (for the USA). As an example, the overall formulation can have a density of 820 to 845 kg / m3 at 15 ° C; a T95 boiling point (ASTM D86 or EN ISO 3405) of 360 ° C or less; a measured cetane number of 40 or greater, ideally 51 or greater; a VK40 of 2 to 4.5 mm2 / s; a flash point (ASTM D93 or EN ISO 2719) of 55 ° C or higher; a sulfur content (ASTM D2622 or EN ISO 20846) of 50 mg / kg or less; a cloud point (IP 219) of less than -10 ° C; and / or a polycyclic aromatic hydrocarbon (PAH) content (EN 12916) of less than 11% w / w. It can have a lubricity, measured using a high frequency reciprocating device, for example, according to ISO 12156 and expressed as a “HFRR wear scar”, of 460 pm or less. Relevant specifications may, however, differ from region to region, from season to season and from year to year and may depend on the intended use of the formulation. In addition, a formulation used according to the invention may contain individual combustible components with properties outside these ranges, since the properties of a total mixture can often differ significantly from those of their individual constituents.

[00044] A fuel formulation used in accordance with the present invention may comprise one or more fuel or refinery additives, in particular additives that are suitable for use in automotive diesel fuels. Many of such additives are known and commercially available. The formulations can, for example, comprise one or more additives selected from detergents, de-creams, anti-corrosion additives, anti-foam additives, cetane improvers, such as 2-ethylhexyl nitrate (2-EHN), antistatic additives, lubricity additives, conductivity additives , cold flow additives and their combinations. They may comprise one or more additives selected from detergents, deodorizers, anti-corrosion additives, anti-foam additives and mixtures thereof. Such additives can be included in a (active substance) concentration of up to 300 ppmw (parts per million by weight), for example, from 50 to 300 ppmw.

[00045] A fuel formulation used in accordance with the present invention must be suitable and / or adapted for use in an internal combustion engine (diesel). It can, in particular, be an automotive fuel formulation. In one embodiment, it is suitable and / or adapted for use in a diesel engine that operates using high fuel injection pressures, for example, pressures greater than about 180 MPa (1800 bar) or about 200 MPa (2000 bar) or greater. Such an engine can, for example, be of the type of common rail or unit injector, and / or of the type referred to as “Euro 5”.

[00046] In embodiments, the present invention can be used to prepare at least 1000 liters of the diesel fuel formulation containing additive, or at least 5000 or 10,000 or 20,000 or 50,000 liters.

[00047] According to the invention, the viscosity-enhancing additive is used for the purpose of increasing the compressibility of a diesel fuel formulation. It can, in particular, be used to increase the compressibility of the formulation at a pressure of 100 MPa (1000 bar) or greater, or 150 MPa (1500 bar) or greater, or 200 MPa (2000 bar) or greater, for example, from 100 to 250 MPa (1000 to 2500 bar) or from 150 to 250 (1500 to 2500 bar) or from 20 to 250 MPa (200 to 2500 bar). It can be used to increase the compressibility of the formulation at a temperature of 100 ° C or higher, or 150 ° C or higher, or from 100 to 250 ° C or from 100 to 200 ° C or from 100 to 175 ° C or from 100 to 150 ° C. In one embodiment, the viscosity-enhancing additive is used to produce a diesel fuel formulation that has an increased compressibility at a pressure of 200 to 250 MPa (2000 to 2500 bar) and a temperature of 100 to 150 ° C, in particular at a pressure of 200 MPa (2000 bar) and a temperature of 150 ° C.

[00048] In the present context, "compressibility" is suitably isothermal compressibility, that is, the rate of change of density with pressure at a constant temperature.

[00049] The isothermal compressibility of a fuel formulation can be evaluated using any suitable method, for example, as described in the examples below. Its reciprocal, referred to as the compressibility module, is typically defined as the ratio of the pressure change to the relative change in density at constant temperature. The isothermal compressibility and the compressibility module can thus be estimated by measuring the density of the fuel formulation in a range of pressures and observing the way in which the density changes with pressure. The results can, for example, be plotted on a density graph in relation to pressure. Density measurements should be taken at a constant temperature, for example, a temperature at which the fuel formulation could typically be subjected to the injection system of a diesel engine. In particular, density measurements can be made at a constant temperature that is in the range of 40 to 200 ° C, or in the range of 40 to 150 ° C, or in the range of 100 to 150 ° C, such as about 150 ° C.

[00050] The density of a fuel formulation can be measured using a standard test method, such as ASTM D4052 or an analogous method.

[00051] The invention can be used to achieve any degree of increase in the compressibility of the fuel formulation and / or to obtain a desired target compressibility, for example, a target established by an applicable regulatory standard, or an established target by a user (including a handler, retainer or distributor) or potential user of the formulation. The increase in compressibility will typically be as compared to the compressibility of the formulation prior to the addition of the viscosity improving additive.

[00052] The invention can be used to achieve a desired increase in compressibility at a specific temperature, or within a specific temperature range. It can be used to achieve a desired increase in compressibility at a specific pressure, or within a specific pressure range.

[00053] "Obtaining" a desired target property also encompasses - and in one embodiment involves - improving the relevant target. Thus, for example, the viscosity-enhancing additive can be used to produce a diesel fuel formulation that has a higher compressibility than a desired target value.

[00054] The increased compressibility of the diesel fuel formulation can be as compared to the compressibility of the formulation and / or otherwise analogous fuel formulation intended (eg, marketed) for use in an analogous context, prior to understanding that the viscosity improving additive could be used in the manner provided by the present invention, or before adding the viscosity improving additive to the formulation according to the invention. Thus, the increase can be as compared to the compressibility of the diesel fuel formulation, without the viscosity-improving additive. At given pressure and temperature, the increase in compressibility can, for example, be 0.5% or more, or 0.75 or 1% or more or in cases 2.5 or 3 or 4 or 5% or more of the compressibility that is desired to improve. At given pressure and temperature, the increase in compressibility can, for example, be up to 20%, or up to 15 or 105, or up to 7.5 or 5%, of the compressibility that is desired to improve.

[00055] The invention can additionally or alternatively be used to adjust any property of the diesel fuel formulation, which is equivalent to or associated with its compressibility, for example, to achieve an increase in a desired property or behavior and / or a reduction in unwanted property or behavior. In particular, an increase in compressibility can be manifested by an improvement in the performance of a fuel consumption system (in particular a diesel engine) operating in the fuel formulation. Such improvement may, for example, comprise a higher supplied torque under constant state conditions (ie, at constant speed and motor load), shorter acceleration times and / or a higher power output (manifested for example by a highest average effective brake pressure). It can thus be manifested by an improvement in one or more aspects related to the power of the performance of the fuel consumption system. According to the invention, the viscosity-enhancing additive can be used in a diesel fuel formulation, for the purpose of obtaining one or more of these effects, in particular to improve the performance related to the power of an engine in which the fuel formulation is, or is intended to be, used. It can be used to increase the combustion energy generated with each injection of the fuel formulation into a combustion chamber of an engine operating in the formulation.

[00056] An improvement in performance related to the power of a fuel consumption system can also encompass mitigation, at least to a degree, of a decrease in acceleration performance, due to another cause, in particular due to another component or additive of fuel included in the fuel formulation in which the system is operating. As an example, a fuel formulation may contain one or more components designed to reduce its total density, in order to reduce the level of emissions that it generates in combustion; a reduction in density can result in loss of engine power, but this effect can be overcome or at least mitigated by the use of a viscosity-enhancing additive, in accordance with the present invention.

[00057] An improvement in performance related to power may also cover restoration, at least partially, of performance that has been reduced for another reason such as the use of a fuel containing an oxygenated component (for example, a so-called “biofuel”), or the formation of deposits related to combustion in the engine (typically in fuel injectors).

[00058] In the context of the present invention, "use" of a viscosity-enhancing additive in a diesel fuel formulation means incorporating the additive into the formulation, typically as a mixture (i.e., a physical mixture) with one or more other components diesel fuel, for example, a diesel fuel and, optionally, one or more other diesel fuel additives. The viscosity-enhancing additive will be conveniently incorporated before the formulation is introduced into an engine or other system that is to be operated in the formulation. Instead of or in addition, the use of a viscosity-enhancing additive may involve operating a fuel consumption system, typically an internal combustion engine, in a diesel fuel formulation containing the additive, typically introducing the formulation into an engine combustion chamber. It may involve operating a vehicle that is powered by a fuel consumption system, in a diesel fuel formulation containing the additive. In such cases, the fuel consumption system is suitably a compression ignition (diesel) engine.

[00059] "Use" of a viscosity-enhancing additive in the manner described above, can also cover supplying the additive along with instructions for its use in a diesel fuel formulation, in order to increase the formulation's compressibility. The additive can itself be supplied as part of a composition that is suitable and / or adapted and / or intended for use as a fuel additive, in which case the viscosity-improving additive can be included in such a composition for the purpose of influence its effects on the compressibility of a diesel fuel formulation.

[00060] In general, references to "adding" a component in, or "incorporating" a component into, a fuel formulation can be interpreted to encompass the addition or incorporation at any point during the production of the formulation or at any time before its use . Thus, for example, the viscosity-enhancing additive can be incorporated into a diesel-based fuel at the refinery or, more appropriately, can be added to a diesel fuel formulation in the deposit downstream of the refinery.

[00061] A diesel fuel formulation, used in accordance with the present invention, can be marketed with an indication that it benefits from an improvement due to the inclusion of the viscosity improving additive, in particular a higher compressibility and / or a improvement in performance related to the power of an engine that is operating in the formulation of fuel. The marketing of such a formulation may comprise an activity selected from (a) providing the formulation in a container that comprises the relevant indication; (b) supply the formulation with product coverage that includes the indication; (c) provide the indication in a publication or brand (for example, at the point of sale) that describes the formulation; and (d) provide the indication in a commercial that is broadcast, for example, on radio, television or the internet. The improvement can be attributed, in this indication, at least partially to the presence of the viscosity improving additive. The invention may involve evaluating the pertinent property (in particular the compressibility) of the formulation during or after its preparation. It may involve evaluating the pertinent property, both before and after the incorporation of the viscosity-improving additive, for example, in order to confirm that the additive contributes to the relevant improvement of the formulation.

[00062] Similarly, a diesel fuel additive composition, containing a viscosity improving additive, according to the invention, can, according to the invention, be marketed with an indication that it benefits from an improvement due to the inclusion of the viscosity-enhancing additive, the improvement being the ability of the composition to increase the compressibility of a diesel fuel formulation in which it is used and / or to improve the performance related to the power of an engine operating in such a diesel fuel formulation.

[00063] Throughout the description and claims in this report, the words "understand" and "contain" and variations of the words, for example, "comprising" and "understand, mean" including but not limited to "and do not exclude other portions, additives, components, integers or steps.

[00064] Preferred details of each aspect of the invention can be as described in connection with any of the other aspects. Other details of the invention will become apparent from the following examples. Generically speaking, the invention extends to any new, or any new combination, of the details described in this report (including any accompanying claims and drawings). Thus, details, integers, characteristics, compounds, chemical components or groups described together with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described here, unless that are incompatible with them.

[00065] Where upper and lower limits are quoted for a property, for example, for the concentration of a fuel component, then a range of values defined by a combination of any of the upper limits with any of the lower limits can also be implied .

[00066] In this report, references to properties of fuel and fuel component are - unless stated otherwise - to properties measured under ambient conditions, that is, at atmospheric pressure and at a temperature of 16 to 22 or 25 ° C , or from 18 to 22 or 25 ° C, for example, about 20 ° C.

[00067] The present invention will now be described further with reference to the following non-limiting examples.

Example 1

[00068] Diesel fuel formulations have been prepared, according to the present invention, by mixing a diesel fuel with four quality improvement test additives. The additives were: SV ™ 150, a fuel additive containing a polystyrene-polyisoprene block copolymer, da-Infineum. b SV ™ 200, a fuel additive, containing a polystyrene-polyisoprene star copolymer, da-Infineum. ç. SV ™ 260, a fuel additive containing a styrene-polyisoprene star copolymer, da-Infineum. d. HNR40D, a lubricant based oil, from Shell.

[00069] The base fuel was a zero sulfur diesel fuel (from Shell), which complies with the European diesel fuel specification EN 590. It contained 7% v / v rapeseed methyl ester (RME), along with standard refinery additives. It had a VK 40 of 2.86 mm2 / s (DIN EN ISO 3104) and a density at 40 ° C of 817.28 kg / m3 (DIN EN ISO 12185).

[00070] HNR40D is a highly refined Group V API mineral oil from Shell. It is manufactured from crude naphthenic oils, via a process involving vacuum distillation and hydro treatment. It has a density at 15 ° C of 880 kg / m3 (ISO 12185); a VK 40 of 7.9 mm2 / s (ISO 3104); a VK 100 of 2.1 mm2 / s (ISO 3104); a flash point of 146 ° C (ISO 2719); a polycyclic aromatic compound (PCA) content (IP 346) of 1% w / w; and a color index (ASTM 1500) less than 0.5.

[00071] The test additives were incorporated into the base fuel at a treatment rate of 0.04% w / w and 0.2% w / w for SV ™ 150; 0.2% w / w for the SV ™ 200; 0.15% w / w for the SV ™ 260 and 26% w / w for the HNR40D.

[00072] The densities of the resulting formulations and of the non-additive base fuel were measured at 100 ° C, using a density sensor, in a series of pressures from 0 to 250 MPa (0 to 2500 bar) (relative to atmospheric) in 25 MPa (250 bar) steps. The experiment was then repeated at 150 ° C.

[00073] The results are shown in Tables 1 and 2 below, for measurements made at 100 ° C and 150 ° C, respectively. The table numbers are the densities of the base fuel and fuel formulation, in kg / m3. A pressure designated “0” corresponds to the ambient pressure (1 bar).

onde V é o volume da amostra de combustível pertinente na temperatura T e pressão P, e VO é o volume da mesma amostra em temperatura T e pressão ambiente (1 atmosfera).[00074] The measured densities were used to calculate the isothermal compressibilities of the base fuel and the test formulations, at each pressure and temperature. Isothermal compressibility at temperature T (KT) is defined as a reduction in fractional volume divided by the associated change in pressure, according to the following formula:

where V is the volume of the relevant fuel sample at temperature T and pressure P, and VO is the volume of the same sample at temperature T and ambient pressure (1 atmosphere).

onde p é a densidade da amostra de combustível em temperatura T e pressão P.[00075] For the present purposes, it can be defined according to the formula:

where p is the density of the fuel sample at temperature T and pressure P.

[00076] The results are shown in Tables 3 and 4 below, for experiments conducted at 100 ° C and 150 ° C, respectively. The table numbers are KT values times 1E-6, per br. Again, a pressure designated as "0" corresponds to the ambient pressure (0.1 MPa (1 bar)).

[00077] Tables 1 and 2 show that viscosity improving additives increase the density of the base fuel, in particular at higher pressures. In addition, the difference between the density of the base fuel additive and that of the base fuel only increases with increasing pressure, indicating an increase in the compressibility of the base fuel, when combined with the relevant additive. This increase in compressibility, compared to that of the base fuel only, is clearly seen in the data in Tables 3 and 4. It is evident at both measurement temperatures, in particular at 150 ° C, which confirms the probable usefulness of the present invention under typical fuel injection conditions.

[00078] When the results in Table 1 are plotted on a density density graph, the curves for the additive fuel formulations can be seen to deviate from the curve for the base fuel only, in particular at higher pressures of about 1000 bar. The rate of change of density with pressure (i.e., compressibility) is, at such higher pressures, significantly higher for the five additive formulations than for the nonadditive base fuel. The increase in compressibility at any given pressure is greater with the SV ™ 150 and SV ™ 260 than with the SV ™ 200. In reality, the SV ™ 150 has an effect even at a treatment rate as low as 0, 04% w / w. Similar comments apply to the results in Table 2, where the divergence of the curves is increased, compared to that seen at 100 ° C.

[00079] The base fuel / HNR40D mixture has a much higher initial density than the base fuel alone. Its density remains higher than that of the base fuel at all pressures, but again its rate of change of density with increasing pressure was shown to be higher than that of the base fuel only, both at 100 and 150 ° C. However, the use of HNR40D base oil, for better isothermal compressibility, requires a much larger amount of the additive (in these examples 26% w / w), while for each of the olefin-based polymeric additives a benefit in compressibility is provided. , when using significantly less - 0.2% w / w or less.

[00080] In total, these results confirm the known relationship between isothermal compressibility and pressure, that is, that the compressibility decreases with increasing pressure. What they also show, however, that was not previously appreciated, is that a small amount of a suitable viscosity-enhancing additive can influence the way in which the compressibility of a diesel fuel formulation changes across the range of injection pressures of fuel, resulting in higher fuel densities under injection conditions.

[00081] Thus, the present invention can provide a way to increase the compressibility of a diesel fuel formulation, in many cases the use of relatively small amounts of compatible additives - diesel fuel. An increase in compressibility means that, at the higher pressures to which an engine's fuel injection system is subjected, the fuel formulation will have a higher density and thus will be supplied, through the volumetrically calibrated injection system, with a greater energy of combustion. In this way, the additive fuel can be used to improve the performance related to the power of a diesel engine.

Claims (7)

1. Use of a viscosity-improving additive, characterized by the fact that it is in a diesel fuel formulation, for the purpose of increasing the isothermal compressibility of the formulation at a pressure of 150 to 250 MPa (1500 to 2500 bar), in that the viscosity improving additive is a polymer based on olefin or naphthenic lubricating oil, and the viscosity improving additive is used in a concentration in the range of 0.01 to 0.5% w / w, and compressibility isothermal formulation is the rate of change of density with pressure at a constant temperature. 2. Use according to claim 1, characterized by the fact that the olefin-based polymer is selected from polyisobutylene (PIBs), polyalpha olefins (PAOs), ethylene-propylene copolymers, styrene-based polymers and mixtures thereof. Use according to claim 2, characterized in that the olefin-based polymer comprises a styrene-based polymer. Use according to claim 3, characterized in that the styrene-based polymer is a copolymer of at least one styrenic monomer with at least one olefinic monomer. Use according to any one of claims 1 to 4, characterized in that the viscosity-improving additive is a viscosity-indexing additive. Use according to any one of claims 1 to 5, characterized in that the viscosity-improving additive is used in a concentration in the range of 0.01 to 0.2% w / w. Use according to any one of claims 1 to 6, characterized in that the viscosity-enhancing additive is used for the purpose of increasing the isothermal compressibility of the diesel fuel formulation at a temperature of 100 to 200 ° C.