WO2017129726A1

WO2017129726A1 - Dialkyl carbonate compounds as anti-soot additives for aviation fuel

Info

Publication number: WO2017129726A1
Application number: PCT/EP2017/051729
Authority: WO
Inventors: Mohammed YAHYAOUI; Isabelle Lombaert-Valot; Gérard Mignani; Nicolas Perret
Original assignee: Rhodia Operations; Airbus Group Sas
Priority date: 2016-01-28
Filing date: 2017-01-27
Publication date: 2017-08-03
Also published as: FR3047249A1

Abstract

The invention relates to the use of a dialkyl carbonate compound as an anti-soot additive for an aviation fuel for turbine engines, said dialkyl carbonate compound being selected from the group consisting of: (A), (B), (C), (D) and mixtures of same, provided that compound C is not used together with a dialkyl dicarbonate compound.

Description

Dialkylcarbonate compounds as anti-soot additives for aviation fuel.

The present invention relates to the use of organic compounds as anti-soot additives for aviation fuels for turbine engines, better known as "Jetfuels" in the English language.

Improving air quality is now a major concern for all industrialized countries. Among the referenced pollutants, the emission, during the combustion of fuel, of carbonaceous particles, more commonly known as "soot", remains a major problem for the environment and health.

In general, soot formation is related to a local oxygen deficiency during fuel combustion. The mechanisms leading to the formation of these soot particles are still poorly known. They involve complex reactions of nucleation, particle surface growth and coagulation. More specifically, macromolecules formed by pyrolysis or oxidation of hydrocarbons condense to give carbon cores less than 2 nm in diameter. On this core are then adsorbed particles from the gas phase, such as polycyclic aromatic compounds or dioxins. Finally, the agglomeration of these primary carbon cores forms a set of particles of size between 10 and 300 nm at the exhaust outlet.

Studies have shown that soot particles are one of the causes of the degradation of air quality, and that they contribute to the phenomenon of global warming. It has also been suggested that soot particles are harmful to health, and more particularly that they are carcinogenic to humans.

For these health and environmental reasons, the limitation of soot emissions remains an important issue.

Currently, in the field of diesel vehicles, the use of particulate filters reduces the emissions of soot particles at the outlet of the muffler and to meet regulatory and health standards. Different so-called regenerative filter technologies have been developed to collect soot particles, and remove the soot so trapped to regenerate the pressure drop of the filters. For obvious reasons, it is preferable to develop means that do not collect and then remove soot, but reduce or even prevent their formation.

Numerous research projects have been carried out in the automotive field, in particular for diesel fuels, and propose to reduce the formation of soot by adding polyoxygenated additives.

For example, various studies (Rounce et al., UK Energy & Fuels (2010), 24 (9), 4812-4819 and Cheung et al., "Performance of diesel engine using diesel fuel blended with dimethyl carbonate", Southeast University Press, Nanjing, Peop, Rep. China CODEN: 69GNB5, CAN 142: 300536) analyze the influence of diesel dimethyl carbonate (DMC) and diethyl carbonate (DEC) diesel fuel on the release of fumes, carbon monoxide or oxides of nitrogen.

Also, Guo et al. propose the addition, in diesel fuels, of di (2-ethoxyethyl) carbonate (Guo et al., "Development of di (2-ethoxyethyl) carbonate as a clean diesel fuel additive", American Chemical Society, Division of Petroleum Chemistry , CODEN: ACPCAT ISSN: 0569-3799, CAN 145: 491855 AN 2006: 270943 and Guo et al, "Development of di (2-ethoxyethyl) carbonate used as a clean diesel fuel additive", American Chemical Society, Washington, DC CODEN: 69HYEC Conference, AN 2006: 249481) or methyl 2-ethoxyethyl carbonate (Guo et al., "Investigation of a new oxygenate, methyl 2-ethoxyethyl carbonate, as a clean diesel fuel additive", Xi'an Research Institute of Hi.-Tech, Xi'an, Peop, Rep. China, American Chemical Society, Washington, DC CODEN: 69GQMP Conference, AN 2005: 190024), to reduce the formation of smoke particles.

It has also been proposed to reduce the formation of soot and fumes emitted by diesel engines, various compounds of (poly) ether type, such as alkylene glycol alkyl ether compounds (US 3,594,136), polyoxyalkanes (US 2010 / 0005707), polyoxymethylene di (alkyl polyglycol) ethers (US 2011/0131871) or dialkyl glycol ethers (GB 1,246,853). On the other hand, few studies relate to the field of aviation fuels. However, the problem of soot emission is also encountered in the field of fuels used in aeronautics, mainly during take-off, when the thrust is maximum.

Aviation fuels for turbine engines (jet engines, turboprops), commonly known as jet fuels, and more commonly known as jet fuels or Aviation Turbine Fuels (ATF), are complex blends of aviation fuels. hydrocarbons, distinct from diesel fuels used in the automotive field; and must meet very strict specifications because of their particular constraints of use. In particular, the performance of the fuel under very low temperature conditions is one of the major concerns in the field of jet fuel, in particular to reduce the risk of clogging due to the precipitation of compounds at low temperatures.

The present invention aims precisely to provide appropriate additives for implementation in aviation fuels for turbine engines ("jet-fuels"), and to reduce the formation of soot.

As mentioned above, such additives must meet the stringent requirements encountered in the field of jet-fuels. Thus, in addition to being soluble in the fuel formulation, it is imperative that these additives do not induce a rise in the freezing point of the jet fuel formulation in which they are used, which, for obvious reasons, could have dramatic consequences. The jet-fuels must thus maintain a very low freezing point to withstand extreme temperature conditions at high altitudes. It is also preferable that these additives do not induce a significant change in the flash point of the jet fuel formulation in which they are implemented.

In addition, it is preferable that these additives do not lower the calorific value of the fuels.

For obvious reasons, it is also important that these additives have a boiling point compatible with their use in an aviation fuel for turbine engines, typically between 140 ° C and 300 ° C (at 1 atm).

Finally, it is important that these additives, during the combustion of the jet fuel, do not cause the formation of toxic derivatives or related pollutants, and do not induce the formation of polymeric or metal layers on the surface of the turbine. According to a first of its aspects, the invention thus relates to the use of a dialkylcarbonate compound as an anti-soot additive for an aviation fuel for turbine engines ("jet-fuel"), said compound dialkylcarbonate being selected from the group consisting

and their mixtures,

provided that compound C is not used in conjunction with a dialkyldicarbonate compound.

In particular, the subject of the invention is the use of a dialkylcarbonate compound as an anti-soot additive for an aviation fuel for jet-fuel engines, said dialkyl carbonate compound being chosen from group consisting of:

and their mixtures.

By "anti-soot additive" is meant a compound which, used in a fuel, in particular a jet fuel, makes it possible to reduce the formation of soot during the combustion of said fuel.

Admittedly, dimethyl carbonate (DMC) and diethyl carbonate (DEC) have already been proposed by Rounce et al. and Cheung et al. as additives to reduce the emission of pollutants in diesel motor fuels.

However, to the inventors' knowledge, it has never been proposed to use the compounds A, B and D of the invention to reduce the formation of soot specifically in an aviation fuel for turbine engines. To the knowledge of the inventors, it has also not been proposed to use compound C of the invention without dialkyldicarbonate to reduce the formation of soot specifically in an aviation fuel for turbine engines.

Unexpectedly, the inventors have discovered that compounds A, B and D of the invention are particularly effective as anti-soot additives in an aviation fuel formulation, or even exhibit improved performance in aviation fuel formulation. reducing soot compared to their efficiency in a diesel fuel.

Likewise, the inventors have discovered that compound C of the invention is particularly effective as an anti-soot additive in an aviation fuel formulation, even in the absence of dialkyldicarbonate, or even performs well. improved soot reduction compared to its efficiency in diesel fuel.

Without wishing to be bound by the theory, the anti-soot effectiveness of the dialkylcarbonates compounds of the invention is due to their ability to trap the first radical species resulting from the thermal degradation of fuels, which are involved in the formation of soot. More specifically, the compounds according to the invention prove to be capable of rapidly creating thermodynamically stable alkyl and / or alkoxyl radicals which, by trapping the first radical species mentioned above, limit or even inhibit the formation of soot.

By "dialkyldicarbonate compound" is meant in particular a compound of formula (I) below:

in which RI and R2, identical or different, represent a linear or branched C 1 -C 10 alkyl group.

R1 and R2 may optionally form together a linear divalent alkyl radical such that the compound of formula (I) is cyclic.

According to the present invention, an "alkyl" group represents a saturated hydrocarbon group, in a straight or branched chain, comprising from 1 to 10 carbon atoms, preferably from 1 to 7 carbon atoms. Mention may in particular be made, when they are linear, the methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl radicals.

When they are branched or substituted by one or more alkyl radicals, mention may be made especially of the isopropyl, tert-butyl, 2-ethylhexyl, 2-methylbutyl, 2-methylpentyl, 1-methylpentyl and 3-methylheptyl radicals.

According to the use of the invention, when the compound C of the invention is used as an anti-soot additive for an aviation fuel for turbine engines, it is not implemented. together with a dialkyldicarbonate compound as defined above, that is to say that said compound C is not in the presence of a dialkyldicarbonate compound within the same formulation and that said compound C is not mixed with a dialkyldicarbonate compound.

According to one embodiment, when any of the compounds A, B, C or D of the invention is used as an anti-soot additive for an aviation fuel for turbine engines, this is not used together with a dialkyldicarbonate compound as defined above, that is to say that it is not in the presence of a dialkyldicarbonate compound within the same formulation and that it is not mixed with a dialkyldicarbonate compound. Preferably, the dialkylcarbonate compound used as an anti-soot additive for an aviation turbine engine fuel is selected from the group consisting of compounds A, B, D and mixtures thereof.

The dialkylcarbonate compounds of the invention may be commercially available or prepared according to synthetic methods described in the literature and known to those skilled in the art.

Application in aviation fuel for turbine engines

The dialkylcarbonate compounds according to the invention can be used as anti-soot additives in an aviation fuel formulation for jet engines. According to another of its aspects, the invention thus relates to a composition comprising at least one aviation fuel for turbine engines and at least one dialkylcarbonate compound selected from the group consisting of compounds A, B, C and D as defined herein. above, and mixtures thereof, provided that when said composition comprises said compound C, it is free of dialkyldicarbonate compound.

According to one embodiment, the composition of the invention is free of dialkyldicarbonate compound (whatever the compound A, B, C or D included in said composition).

According to one embodiment, the composition of the invention comprises at least one aviation fuel for turbine engines and at least one dialkylcarbonate compound selected from the group consisting of compounds A, B and D as defined above, and their mixtures.

Such a composition, also called "supplemented fuel", is particularly suitable as an aviation fuel for turbine engines.

The present invention further relates, in another of its aspects, a receptacle, in particular a fuel tank of a locomotion machine, containing a supplemented fuel as defined above.

The invention also relates to a locomotion device, particularly an aircraft, comprising a supplemented fuel tank as defined above.

According to another of its aspects, the invention also relates to a method for reducing the formation and / or the emission of soot during the combustion of an aviation fuel for turbine engines, comprising the provision to a turbine engine of a composition according to the invention.

"Aviation fuel" means a fuel intended for use in an aircraft, in particular an airplane, and meeting the international specifications established for aviation fuels as set forth below.

In particular, the aviation fuel composition according to the invention may be a fuel intended for the operation of turbine engine engines (turbojet engine, turboprop engine), commonly called "jet fuel" or "jet-fuel" in the language English, and, as such, can more particularly comply with the standards required for jet fuels, for example Jet A-1 jet fuels.

As aviation fuels, for example, the fuels known to those skilled in the art may be mentioned under the following names: JP-4 (MIL-T-5624), JP-5, JP-7 (MIL-T-38219), JP -8 (MIL-T-83133) in the field of military aviation, Jet A, Jet A-1 (ASTM-D 1655) and Jet B in the field of civil aviation, and preferably Jet A-1 .

Aviation fuels are based on kerosene, alone or mixed with gasoline (eg 50% kerosene - 50% gasoline for JP-4, 99.5% kerosene for JP-5 and JP-8, 100% kerosene for Jet A-1) and include additives adjusted for specific uses of the fuel, such as, for example, antioxidants, corrosion inhibitors, metal catalysis inhibitors, icing inhibitors, in limited quantities.

In general, jet fuels are produced from a kerosene fraction derived directly from the atmospheric distillation of crude oil and whose distillation points are between 140 ° C and 300 ° C, and carbon chains from 9 to 16 atoms. of carbon.

Aviation fuels have the particularity of having to meet the same levels of specifications worldwide, resulting directly from the particular conditions, in particular extreme temperature variations, in which they are used. The properties and specifications of these aviation fuels are more particularly detailed in the document: "Kerosene / Jet Fuel Category Assessment Document", submitted to the US EPA by the American Petroleum Institute, September 21, 2010. Particularly advantageous aircraft fuels for example, those complying with the AFQRJOS specification (Issue 18) for the Jet A-1 of March 2015 (this specification includes the most stringent criteria of the ASTM D 1655 specification and the British specification DEF STAN 91-91).

In civil aviation, the most common fuel is Jet A-1 jet fuel. This must have a freezing point below -47 ° C (typical value of -50 ° C). Jet-A with a freezing point of -40 ° C is of inferior quality to Jet A-1 and mainly used in the United States; Jet B with a freezing point Below -50 ° C, the trade name of JP-4, is only used in very cold climates.

These aviation fuels all have a calorific value of between 42.8 and 43.6 MJ / kg. The minimum flash point is 60 ° C for JP-5, 38 ° C for Jet A-1 and JP-8 (typical value for Jet A-1 of 50 ° C). The characteristic densities are 810 kg / m ³ for the Jet A-1, 760 kg / m ³ for the Jet B.

Other specifications can still be quoted. For example, the Jet A-1 must imperatively have a sulfur content of less than 0.30% by weight, and a content of aromatic compounds of less than 22% by volume (25% for the international standard AFQRJOS).

Of course, the dialkyl carbonate compound (s) of the invention are added to the conventional fuel, for example a Jet A-1 fuel, in an amount such that they do not affect the specifications to which this fuel must meet.

Thus, according to a particular embodiment, an aviation fuel composition according to the invention has a freezing point below -40 ° C, in particular between -60 and -40 ° C, preferably below -47 ° C. ° C, and can thus be adapted to its potential use in cold conditions, for example in the context of use in civil aviation or military.

Preferably, an aviation fuel composition according to the invention has a good calorific value, in particular greater than 40 MJ / kg, in particular greater than 42.5 MJ / kg, preferably greater than 42.8 MJ / kg. (international standard AFQRJOS).

It is understood that a dialkylcarbonate compound according to the invention can be added to a fuel formulation, alone or in combination with one or more other dialkylcarbonates compounds according to the invention.

It is up to those skilled in the art to adapt the content of anti-soot additive (s) according to the invention to introduce into the fuel formulation, in particular with regard to the composition of the fuel, the said anti-soot additive (s). implemented, and expected anti-soot properties.

The said dialkylcarbonates compound (s) according to the invention are more particularly introduced into a fuel formulation in a content such that they are soluble in the fuel formulation. In general, said dialkylcarbonates compound (s) may be used in a conventional aviation fuel formulation, in a proportion of 0.1% to 20% by mole, in particular from 0.5% to 10% by mole, preferably from 1% to 5% molar.

Thus, the composition according to the invention may comprise from 0.1% to 20% by mole, in particular from 0.5% to 10% by mole, preferably from 1% to 5% by mole, of one or more dialkylcarbonate compounds conforming to the invention.

For the purposes of the present invention, it should be noted that the terms "ranging from ... to ..." and "between ... and ..." mean that the terminals are included, unless otherwise specified.

Unless otherwise indicated, the expression "comprising / including a" shall be understood as "comprising / including at least one".

Examples

Materials and methods

The anti-soot performance of additives according to the present invention were tested by YSI measurement (Yield Sooting Index), implementing the device and methodology described in detail in McEnally et al. Combust. Flame 2007, Vol.148, 4, 210-222.

According to this methodology, the maximum volume fraction of soot f _v , max is measured in a laminar methane / air diffusion flame whose flow is doped upstream of the combustion by a small amount of vapors of the fuel supplemented (or not) to be studied. .

Laser extinction measurements (Light Extinction Laser) were carried out to measure the volume fraction of soot in the flames thus produced. In a schematic manner, a laser passing through said flames is partially obscured by the opaque particles of soot generated by the combustion of the supplemented fuel. A camera placed downstream of the flame allows the acquisition of the residual light having passed through the flame.

Methods of processing the signal thus captured then made it possible to access the YSIs for each fuel supplemented (or not) tested.

The fuels used are n-decane or mixtures of n-decane and toluene. These mixtures advantageously mimic the combustion behavior of conventional aviation fuels, especially the formation of soot. In particular, toluene tends to generate a large amount of soot due to its aromatic nature. The molar content of toluene in n-decane is 0%, 4% or 8% depending on the experiments.

The fuels used are free of dialkyldicarbonate compound. The additives used in the supplemented fuels are the compounds A, B, C and D according to the invention, represented below. The molar content of additives in the fuel considered is 0%, 1.96%, 6.54% or 10.7% depending on the experiments.

A B D

Results

Influence of toluene content

The results of Table 1 below were obtained by varying the molar content of toluene in the fuel tested, in order to simulate a variable content of aromatic in the fuel.

Table 1

It is observed that the additives A to D according to the invention make it possible to effectively lower the YSI of the fuels supplemented with respect to non-supplemented fuels (reference), in the absence of dialkyldicarbonate. Influence of the additive content according to the invention

The results in Table 2 below were obtained by varying the molar content of additive in the fuel tested, namely a mixture of n-decane and toluene (8 mol%).

Table 2

It is observed that the additives A to D according to the invention make it possible to effectively lower the YSI of the fuels supplemented with respect to the unsupplemented fuel (reference), in the absence of dialkyldicarbonate.

In the above experiments, the most interesting anti-soot performance was obtained with additive C, in the absence of dialkyldicarbonate.

Claims

1. Use of a dialkylcarbonate compound as an anti-soot additive for an aviation fuel for turbine engines, said dialkyl carbonate compound being selected from the group consisting of:

and their mixtures,

The use of claim 1, wherein said dialkyl carbonate compound is not used in conjunction with a dialkyldicarbonate compound.

Use according to claim 1 or 2, wherein said dialkyl carbonate compound is selected from the group consisting of:

and their mixtures.

A composition comprising at least one aviation fuel for turbine engines and at least one dialkylcarbonate compound selected from the group consisting of compounds A, B, C and D as defined in claim 1, and mixtures thereof, provided that when said composition comprises said compound C, it is free of dialkyldicarbonate compound.

5. Composition according to claim 4, characterized in that it is free of dialkyldicarbonate compound.

The composition of claim 4 or 5, wherein said dialkyl carbonate compound is selected from the group consisting of compounds A, B and D as defined in claim 1, and mixtures thereof.

7. Composition according to any one of claims 4 to 6, comprising from 0.1% to 20% by mole, in particular from 0.5% to 10% by mole, preferably from 1% to

5 mol% of said dialkylcarbonate compound (s) as defined in claim 1.

The composition of any one of claims 4 to 7, wherein the aviation fuel is selected from the group consisting of Jet A, Jet Al, Jet B, JP-4, JP-5, JP-7, and JP-8, said aviation fuel being preferably Jet Al.

A method for reducing the formation and / or emission of soot during the combustion of an aviation fuel for turbine engines, comprising supplying a turbine engine with a composition as defined in one embodiment. Claims 4 to 8.