JP5132937B2 - Fuel composition containing C4-C8 alkyl levulinate - Google Patents

Description

The present invention relates to gas oil-based fuel-containing fuel compositions, in particular compositions of this type containing levulinate esters, in particular C _4-8 alkyl levulinate, and to their preparation and use.

  It is known to blend two different fuel components in order to modify the properties and / or performance of the fuel composition, such as engine performance. Known diesel fuel components include biofuels derived from biological materials, specific examples of which include levulinate esters.

  For the preparation of levulinic acid esters (esters of levulinic acid) and levulinic acid esters, in particular methyl, ethyl, propyl, butyl, pentyl and hexyl esters by reaction of suitable alcohols with furfuryl acetate, see Zh. Prikl. Khim. (Leningrad) (1969) 42 (4), 958-9.

WO-A-94 / 21753 describes a certain proportion of an ester of C _4-6 keto-carboxylic acid, preferably levulinic acid and C _1-22 alcohol (eg 1-90% by volume, 1-50% by volume, preferably 1-20% by volume) and a fuel for an internal combustion engine containing both gasoline and diesel fuel. It is stated that it is particularly preferred that gasoline fuels contain esters with C _1-8 alcohols and diesel fuels contain esters with C _9-22 alcohols.

  All of the examples of WO-A-94 / 21753 contain a certain amount of levulinic acid ester to improve the octane number (RON and MON).

WO-A-03 / 002696 is much more than conventional oxygenates such as ethanol or MTBE or ETBE that have little or no increase in the fuel lead vapor pressure or little or no effect on the flash point of the base fuel. A fuel incorporating levulinic acid or a functional derivative thereof for the purpose of imparting a large amount of oxygen is disclosed. The functional derivative is preferably an alkyl derivative, more preferably a C _1-10 alkyl derivative. It states that ethyl levulinate is preferred or alternatively methyl levulinate is preferred. The levulinic acid or functional derivative is preferably used in an amount of 0.1 to 5% by volume based on the fuel.

WO-A-03 / 002696 states that “The above is illustrated in the following examples” (page 11, line 31), but the composition and test result data are described as follows.
“A standard gasoline blend containing 5.0% or less ethyl levulinate, 1.0% water and 2.0% nonionic surfactant was found to have an RVP similar to the base gasoline.”
“A standard gasoline blend containing 5.0% or less ethyl levulinate, 1.0% water and 2.0% nonionic surfactant was found to have a flash point similar to base diesel.”

  Currently, compression ignition (diesel) engines available on the market tend to be optimized to run with fuel having the desired specifications. Furthermore, the conditions required for engine operation affect the operating attitude of the fuel composition within the engine. In particular, when the atmospheric temperature decreases, the miscibility of components in the fuel composition decreases. Such a decrease in miscibility manifests itself as an increase in the phase separation temperature. The phase separation temperature is defined as the temperature at which the mixture separates into a plurality of distinct immiscible layers upon cooling. Thus, blending a commercially available standard diesel base fuel with other fuel components to modify the overall fuel characteristics and / or performance may adversely affect the intended performance of the resulting blend in the engine.

  Running an engine with a fuel blend instead of a standard base fuel can be even more complicated. Within an engine fuel injection system, the fuel contacts a particular elastomeric material, particularly a fuel pump seal. In use, many of these elastomers swell to some extent in contact with diesel fuel. The degree of swelling depends on, for example, the chemistry of the fuel that acts to promote swelling, the aromatic fuel component, and the oxygenate.

  New elastomers in fuel injection systems tend to equilibrate with a uniform fuel diet and thus provide a reasonable consistency for the required level of sealing. However, if any significant change in the degree of swelling of the elastomer occurs in the fuel diet, the elastomer becomes vulnerable. In the worst case, the mixed fuel diet can put pressure on the elastomeric components of the engine to the extent that fuel leakage occurs.

  For these reasons, it is desirable for any diesel fuel blend to have an overall specification that is as close as possible to a commercially available standard diesel base fuel intended for engine optimization.

However, it may be difficult to give such an overall specification to a diesel fuel blend because any additional fuel components tend to alter the characteristics and performance of the base fuel. Furthermore, it is not always clear to predict the properties of the blend, particularly the effects on engine elastomer parts and low temperature performance, from the properties of the constituent fuel alone.
WO-A-94 / 21753 WO-A-03 / 002696 EP-A-0583836 WO-A-97 / 14768 WO-A-97 / 14769 WO-A-00 / 11116 WO-A-00 / 11117 WO-A-01 / 83406 WO-A-01 / 83648 WO-A-01 / 83647 WO-A-01 / 83641 WO-A-00 / 20535 WO-A-00 / 20534 EP-A-1101813 US-A-5766274 US-A-5378348 US-A-5888376 US-A-6204426 GB-A-960493 EP-A-0147240 EP-A-0482253 EP-A-0613938 EP-A-0557516 WO-A-98 / 42808 US-A-4208190 WO-A-94 / 33805 WO-A-94 / 17160 US-A-5484462 US-A-5490864 WO-A-98 / 01516 Zh. Prikl. Khim. (Leningrad) (1969) 42 (4), 958-9 Danping Wei and H.C. A. An article by Spikes, “The Lubricity of Diesel Fuels” Wear, III (1986) 217-235.

In the fuel composition containing the gas oil base fuel and the alkyl levulinate, when the alkyl levulinate is selected from the C _4-8 alkyl _levulinate group, the phase separation temperature of the fuel composition can be secured below a predetermined level this time. It was unexpectedly found. The fuel composition containing the C _4-8 alkyl levulinate group can also be more compatible with certain elastomeric seal materials than the same type of composition containing a similar concentration of ethyl levulinate. It was surprisingly found that the compatibility with the base fuel is not very different.

For example, replacing 5% by volume ethyl levulinate blended with a specific base fuel with 5% by volume specific C _4-8 alkyl levulinate greatly reduces the phase separation temperature, ie base fuel and levulinate ester. Improves miscibility with. This can of course be particularly advantageous when the fuel blend is used in a low temperature environment. In addition, the levulinic acid C _4-8 alkyl-containing blend, the impact on the swelling and hardness of the elastomer was found to be substantially less than the ethyl levulinate containing blend.

Accordingly, the present invention provides a fuel composition comprising a gas oil-based fuel and an alkyl levulinate, wherein the alkyl levulinate is a C _4-8 alkyl levulinate. For the purpose of ensuring the phase separation temperature of the fuel composition below a predetermined level, the alkyl levulinate may be n-butyl levulinate, n-pentyl levulinate, 2-hexyl levulinate and 2-ethylhexyl levulinate. It is preferred to select from the group _C4-8 alkyl levulinate. The level is preferably less than −10 ° C., more preferably less than −20 ° C., and most preferably less than −30 ° C. Preferably, the alkyl levulinate is levulinate C _4-6 alkyl group, more or preferably selected n- butyl levulinate, 2-hexyl, from levulinic acid n- pentyl and levulinic acid 2-hexyl, or the alkyl levulinate is levulinate C ₅ alkyl. In this fuel composition, the alkyl levulinate is preferably n-pentyl levulinate.

The present invention for the purpose of ensuring a phase separation temperature of a fuel composition containing a gas oil base fuel and an alkyl levulinate below a predetermined level, the fuel composition, levulinic acid C as said alkyl levulinate _4- A method using ₈ alkyl is also provided. The level is preferably less than −10 ° C., more preferably less than −20 ° C., and most preferably less than −30 ° C. In this use, the alkyl levulinate is preferably selected from the C _4-6 alkyl levulinate group, more preferably n-butyl levulinate, n-pentyl levulinate and 2-hexyl levulinate, or the levulin acid alkyl is levulinate C ₅ alkyl. In this method of use, the alkyl levulinate is preferably n-pentyl levulinate.

Furthermore, the present invention provides a fuel composition characterized in that at least a part of ethyl levulinate in a fuel composition containing a gas oil-based fuel and ethyl levulinate is substituted with C _4-8 alkyl levulinate. A method for reducing the phase separation temperature is also provided. This method is characterized in that the phase separation temperature is lowered below a predetermined level, preferably below -10 ° C, more preferably below -20 ° C, most preferably below -30 ° C.

  Still further, the present invention provides a method for operating a compression ignition engine and / or an automobile powered by this type of engine, characterized in that the fuel composition of the present invention is introduced into the combustion chamber of the compression ignition engine.

  Furthermore, the present invention also provides a method for operating the heating apparatus, characterized in that the fuel composition of the present invention is supplied to a burner of a small heating apparatus having a burner.

Still further, the present invention provides a method for producing a fuel composition characterized by blending a gas oil based fuel and a C _4-8 alkyl levulinate. Said alkyl levulinate in this way, preferably levulinic acid C _4-6 alkyl group, more preferably n- butyl levulinate, choose from the levulinate n- pentyl and levulinic acid 2-hexyl, or the alkyl levulinate is levulinate _{C 5} alkyl. In this process, the alkyl levulinate is preferably n-pentyl levulinate.

In all aspects of the invention, the fuel composition may contain a blend of two or more of the C _4-8 alkyl levulinate group, such as a blend of n-butyl levulinate and n-pentyl levulinate. In the context of the present invention, the particular components of the blend and the proportions of these components will depend on one or more desired characteristics of the fuel composition.

  The present invention is an alternative to state-of-the-art standard diesel-based fuels, especially for commercially available diesel engines, such as “biofuels” derived from organic matter that are increasingly used due to commercial and legal pressures. It can be used to formulate fuel blends that are expected to be used.

  In the context of the present invention, “use” of a fuel component in a fuel composition is convenient before the fuel composition is introduced into the engine, but the fuel component is usually blended (ie, a physical mixture). As used herein, it is meant to be introduced into the fuel composition together with one or more other fuel components.

The fuel composition usually contains the majority of the base fuel, for example 50-99% by volume, preferably 50-98% by volume, more preferably 80-98% by volume, most preferably 90-98% by volume. The proportion of C _4-8 alkyl levulinate is selected to obtain the desired degree of miscibility, ie phase separation temperature and elastomer swelling and hardness effects, but depending on other properties required for the overall composition. May be affected.

  The effects on the elastomeric engine components include, for example, the physical properties (eg, volume, hardness and / or dipping) of a given elastomeric material in contact with the relevant fuel or fuel composition, preferably in a diesel engine with the relevant fuel introduced. Changes in flexibility). Usually these changes are volume increase and / or hardness decrease. These changes may be measured using standard test methods such as BS903, ASTM D471, D2240 or ISO 1817: 1998 described in Example 2 below. In particular, nitrile (including hydrogenated nitrile) elastomers or fluorocarbon elastomers may be evaluated.

In the fuel composition, the C _4-8 alkyl levulinate group contains any given elastomeric material (eg, LR) at such a rate that a volume change occurs that is not very different from the volume change caused by the base fuel tested under the same conditions. 6316 (a fluorocarbon type such as James Walker & Co. Ltd., UK).

In the fuel composition, the C _4-8 alkyl levulinate group contains any given elastomeric material (eg, LR) at such a rate that a hardness change occurs that is not very different from the hardness change caused by the base fuel tested under the same conditions. Preferably, it includes a fluorocarbon type such as 6316). Even more preferably, this ratio is less than the change in elastomer hardness with the base fuel alone, ideally 95% or 90% or 85% or less of the change in hardness that occurs with the base fuel. It is.

  Relevant fuel compositions of the present invention include industrial gas oils used in diesel compression and heating applications (eg, boilers) for automotive compression ignition engines and other types of engines such as ships, railways and stationary engines. Is mentioned. The base fuel itself may contain a mixture of two or more different diesel fuel components and / or may contain additives as described below.

Such diesel fuel typically contains liquid hydrocarbon middle distillate gas oil, such as petroleum derived gas oil. These fuel components are not Fischer-Tropsch derived, but can be derived organically or synthetically. The boiling range of this type of fuel is the normal diesel range 150-400 ° C., depending on grade and application. The density is 750 to 900 kg / m ³ at 15 ° C., preferably 800 to 860 kg / m ³ (for example, ASTM D4502 or IP 365), and the cetane number (ASTM D613) is 35 to 80, more preferably 40 to 75. is there. Usually, the initial boiling point is in the range of 150-230 ° C, and the final boiling point is in the range of 290-400 ° C. The kinematic viscosity at 40 ° C. (ASTM D445) may suitably be 1.5 to 4.5 mm ² / s.

Such industrial gas oils contain a base fuel that includes fuel fractions such as kerosene or gas oil fractions obtained in conventional refinery processes. These fuel fractions improve the quality of crude oil into useful products. These fractions preferably contain components having 5 to 40 carbon atoms, more preferably 5 to 31, even more preferably 6 to 25, most preferably 9 to 25, and 650 to 950 kg / m ³ at 15 ° C. It has a density, a kinematic viscosity of 1-80 mm ² / s at 20 ° C and a boiling point in the range of 150-400 ° C.

A non-mineral oil-based fuel, such as a biofuel or a Fischer-Tropsch derived fuel, may optionally be formed in the fuel composition.
The amount of Fischer-Tropsch derived fuel used in the diesel fuel composition may be 0.5-100% by volume, preferably 5-75% by volume, based on the total diesel fuel composition. The composition may contain Fischer-Tropsch derived fuel, desirably 10% by volume or more, more preferably 20% by volume or more, and still more preferably 30% by volume or more. It is particularly preferred that the composition contains 30 to 75% by volume of Fischer-Tropsch derived fuel, in particular 30 or 75% by volume. The balance of the fuel composition is composed of one or more other fuels.

The industrial gas oil composition preferably contains more than 50%, more preferably more than 70% by weight of the Fischer-Tropsch derived fuel component.
Such Fischer-Tropsch derived fuel components are fractions of any middle distillate fuel range that can be isolated from (hydrocracked) Fischer-Tropsch synthesis products. The usual fraction is the boiling range of naphtha, kerosene or gas oil. Fischer-Tropsch products in the boiling range of kerosene or gas oil are preferred because they are easy to handle, for example, in the domestic environment. Such products contain a fraction having a boiling range of 160-400 ° C., preferably about 370 ° C. or less, exceeding 90% by weight. Fischer-Tropsch derived kerosene and gas oil are EP-A-0583836, WO-A-97 / 14768, WO-A-97 / 14769, WO-A-00 / 11116, WO-A-00 / 11117, WO- A-01 / 83406, WO-A-01 / 83648, WO-A-01 / 83647, WO-A-01 / 83634, WO-A-00 / 20535, WO-A-00 / 20534, EP-A- 1101813, US-A-5766274, US-A-5378348, US-A-5888376 and US-A-6204426.

  The Fischer-Tropsch product preferably contains more than 80% by weight of iso- and normal-paraffins, more preferably more than 95% by weight and less than 1% by weight of aromatics, the balance being naphthenic compounds It is. The sulfur and nitrogen content is very low or contains undetectable levels of these compounds. For this reason, the sulfur content of a fuel composition containing a Fischer-Tropsch product can be very low.

The sulfur content in the fuel composition is preferably 5000 ppmw or less, more preferably 500 ppmw or less, 350 ppmw or less, 150 ppmw or less, 100 ppmw or less, or 50 ppmw or less, and most preferably 10 ppmw or less.
In addition to C _4-8 alkyl levulinate, the fuel composition of the present invention contains one or more additives as described below, if necessary.

  The base fuel itself may or may not contain additives. For example, when containing additives in refineries, for example, antistatic agents, pipeline drag reducers, flow improvers (eg, ethylene / vinyl acetate copolymers or acrylate / maleic anhydride copolymers) and wax precipitation Inhibitors (eg “PARAFLOW” (eg from PARAFLOW ™ 450, from Infineum), “OCTEL” (eg from OCTEL ™ W 5000, from Octel) and “DODIFLOW” (eg from DODIFLOW ™ v 3958, from Hoechst) A small amount of one or more additives selected from (commercially available under the trade name) may be contained.

  Detergent-containing diesel fuel additives are known and are commercially available from, for example, Infineum (eg, F7661 and F7685) and Octel (eg, OMA 4130D). Such additives are intended to simply reduce or retard engine deposit build-up (its “standard” rate is typically less than 100 ppmw throughout the additive-containing fuel composition). Of the active component) may be added to the diesel fuel.

  Examples of detergents preferably used for additives for the purposes of the present invention include polyolefin substituted succinimides or succinamides of polyamines such as polyisobutylene succinimide or polyisobutylene amine succinamide, aliphatic amines, Mannich bases or amines and polyolefins ( For example, polyisobutylene) maleic anhydride. Succinimide dispersible additives are described, for example, in GB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-0613938, EP-A-0557516 and WO-A-98 / 42808. . Particularly preferred are polyolefin-substituted succinimides such as polyisobutylene succinimide.

  The additive may contain other components in addition to the cleaning agent. Specific examples are lubricity enhancers; dehazers, such as alkoxylated phenol formaldehyde polymers, such as NALCO ™ EC5462A (formerly 7D07) (from Nalco) and TOLAD ™ 2683 (from Petrolite) as commercial products. Defoaming agents (eg, polyether-modified polysiloxanes, commercially available TEGOPREN ™ 5851 and Q 25907 (from Dow Corning), SAG ™ TP-325 (from OSi), or RHODORSIL ™ (Rhone Poulenc) From)); ignition modifiers (cetane improvers) (eg 2-ethylhexyl nitrate (EHN), cyclohexyl nitrate, di-tret-butyl peroxide and US-A-4208190 Column 2, line 27 to column 3, line 21); rust inhibitors (for example, those marketed as “RC4801” by Rhein Chemie, Mannheim, Germany, propane-1,2-tetrapropenyl succinic acid) Diol half ester, or polyhydric alcohol ester of succinic acid derivative, succinic acid derivative having unsubstituted or substituted aliphatic hydrocarbon group having 20 to 500 carbon atoms on at least one α-carbon atom, for example, polyisobutylene substitution Pentaerythritol diester of succinic acid); corrosion inhibitor; flavoring agent; antiwear additive; antioxidant (eg phenols such as 2,6-di-tert-butylphenol, or N, N′-di-sec -Phenylenediamines such as butyl-p-phenylenediamine); and metal deactivators.

  When the sulfur content in the fuel composition is small (for example, 500 ppmw or less), it is preferable that the additive contains a lubricity enhancer. In the additive-containing fuel composition, the lubricity enhancer is conveniently present at a concentration of 50 to 1000 ppmw, preferably 100 to 1000 ppmw, based on the total fuel composition. Suitable commercially available lubricity enhancers include, for example, EC 832 and PARADYNE ™ 655 (from Infineum), HITEC ™ E580 (from Ethyl Corporation) and VEKTRON ™ 6010 (from Infineum) and Lubrizol Chemical Co. For example, an amide-based additive available as LZ 539 C is mentioned. Other lubricity enhancers are described in, for example, the following documents in connection with the above-mentioned patent documents, in particular the use in low sulfur content diesel fuels.

Danping Wei and H.W. A. An article by Spikes, “The Lubricity of Diesel Fuels” Wear, III (1986) 217-235.
WO-A-94 / 33805: Low temperature flow improver for enhancing the lubricity of low sulfur fuels WO-A-94 / 17160: Carboxylic acid (carbon) as a fuel additive for friction reduction in diesel engine injection systems Contains specific esters and alcohols (having 1 or more carbon atoms) of 2 to 50 atoms, in particular glycerol monooleate and di-isodecyl adipate.
US-A-5484462 describes linolenic acid dimer as a commercial lubricant for low-sulfur diesel fuel (Column 1, line 38), which itself provides aminoalkylmorpholine as a fuel lubricity improver.
US-A-5490864: Specific dithiophosphoric diester-dialcohol as an anti-wear lubricant additive for low-sulfur diesel fuels WO-A-98 / 01516: In particular to provide anti-wear lubricity effects on low-sulfur diesel fuels Specific alkyl aromatic compounds having at least one carboxyl group bonded to an aromatic nucleus.

Moreover, it is preferable that an additive contains an antifoamer, More preferably, it contains an antifoamer combining a rust inhibitor and / or a corrosion inhibitor, and / or a lubricity additive.
Unless otherwise specified, the concentration of each additional component in the additive-containing fuel composition is preferably 10,000 ppmw or less, more preferably in the range of 5 to 1000 ppmw, advantageously 75 to 300 ppmw, such as 95 to 150 ppmw. Range.

  The (active matter) concentration of the defogging agent in the fuel composition is preferably in the range of 1-20 ppmw, more preferably 1-15 ppmw, even more preferably 1-10 ppmw, advantageously 1-5 ppmw. The concentration of (active matter) of other components is preferably in the range of 1 to 20 ppmw, more preferably 1 to 15 ppmw, still more preferably 1 to 10 ppmw, and advantageously 1 to 5 ppmw, excluding the ignition improver. If an ignition modifier is present, its (active component) concentration is preferably 600 ppmw or less, more preferably 500 ppmw or less, conveniently 300 to 500 ppmw.

  The additive components as described above may be mixed into the additive concentrate, preferably together with a suitable diluent, if desired, and the additive concentrate is suitable for obtaining the composition of the present invention. It may be dispersed in the fuel in any amount.

In the case of diesel fuel, the additive may be, for example, a detergent or diesel fuel compatible diluent (which may be a carrier oil (eg mineral oil)), optionally with other ingredients as described above; a polyether (cap) Non-polar solvents such as those sold by affiliates of the Royal Dutch / Shell group under the trademarks "Towel, Xylene, White Spirit" and "SHELLSOL"; and / or esters, and in particular Royal Dutch / Shell under the trademark of alcohols such as hexanol, 2-ethylhexanol, decanol, isotridecanol and alcohol mixtures such as “LINEVOL”, especially LINEVOL ™ 79 alcohol (mixture of C _7-9 primary alcohol) Group affiliates It contains a polar solvent such as the alcohol mixture sold more or the mixture of C _12-14 alcohols sold under the trademark “SIPOL” from Sidobre Sinnova (France).

The total content of additives is suitably 0 to 10,000 ppmw, preferably less than 5000 ppmw.
The concentration of _C4-8 alkyl levulinate in the fuel composition is consistent with one or more of the following parameters.
(I) 1% by volume or more, (ii) 2% by volume or more, (iii) 3% by volume or more, (iv) 4% by volume or more, (v) 6% by volume or less, (vi) 8% by volume or less, (vii ) 10% by volume or less, (viii) 12% by volume or less, and features (i) and (viii); (ii) and (vii); (iii) and (vi); and (iv) and (v ) Is gradually more preferable.

As used herein, the amount of ingredients (concentration, volume%, ppmw, weight%) is the active ingredient, ie, the active ingredient excluding volatile solvents / diluent materials.
The present invention is particularly useful when the fuel composition is used or intended for direct injection diesel engines such as rotary pumps, in-line pumps, unit pumps, electronic unit injectors or ordinary rails, or indirect injection diesel engines. it can. There may be particular value in rotary diesel engines and other diesel engines that rely on the mechanical operation of fuel injectors and / or low pressure pilot injection systems. The fuel composition can be suitably used for heavy and / or light diesel engines.

  It can also be used when the fuel composition is used for heating applications such as boilers such as standard boilers, low temperature boilers, condensing boilers and the like. These boilers are typically used for heating industrial or household water such as space heating and water heating.

The present invention can achieve any of a number of advantageous effects, such as good low temperature performance of the engine.
The invention will now be described with reference to the following examples.

The fuel was blended with the additive by adding the additive to the base fuel at ambient temperature (20 ° C.) and homogenizing.
The following additives were used.
Ethyl levulinate (obtained from Avocado)
・ N-butyl levulinate (obtained from Aldrich)
N-pentyl levulinate (obtained from City Chemical or by reaction of 1-pentanol (obtained from Aldrich) and levulinic acid (obtained from Aldrich))
2-hexyl levulinate (produced by reaction of 1-hexane (obtained from Fluka) or 2-hexanol (obtained from Aldrich) with levulinic acid)

Example 1
Miscibility of alkyl levulinate in diesel fuel (AGO):
The miscibility of the levulinate ester depends to some extent on the characteristics of the base fuel. In order to investigate this effect, three general base fuels (1) to (3) below in the European market were selected. (1) Fuel A is a typical ultra-small sulfur-containing diesel (ULSD) of 2005 standard European diesel fuel, has a cloud point of -8 ° C and an aromatic content of 25% m. (2) Fuel B is Dryfus ULSD, has a low cloud point (−27 ° C.), is composed of hydrogenated AGO having the same aromatic content (22% m) as Fuel A, and conforms to European standard EN590. (3) Fuel C is a low density, low aromatic (4% m) diesel fuel composed of Swedish Class 1 AGO and has the lowest cloud point (−38 ° C.) among these base fuels.
The characteristics of fuels A, B, and C are shown in Table 1.

  For screening purposes, a simple test method was used to determine the mixing limit of ethyl levulinate at room temperature (20 ° C.). The correct volume of ethyl levulinate was continuously added to a known amount of diesel fuel in a 15 ml glass bottle, shaken and observed. The initial appearance of haze was recorded as the room temperature limit of miscibility for the mixture. The results are shown in Table 2. As is apparent from this table, fuel C was the toughest of the three base fuels tested. This fuel was selected for further miscibility testing.

The miscibility of various alkyl levulinates was measured using a method based on the ASTM D2500 “Cloud Point” method. In this method, a fuel sample (40 ml) is cooled from ambient temperature (20 ° C.) in a series of thermostats maintained at progressively lower temperatures. Samples are examined at 1 ° C intervals as they cool to the wax cloud point. In addition to the wax cloud point temperature described in ASTM D2500, the following observations:
(1) The first cloudy appearance,
(2) The first sign of the separation liquid phase shedding,
If these happened, two more temperatures were recorded.

  In each case, cooling continued to the wax cloud point, but no further phase separation could be observed reliably beyond the cloud point.

  Fuel C solutions of ethyl levulinate, n-butyl levulinate and n-pentyl levulinate were blended at various concentrations and the miscibility of each blend was measured. The results are shown in Table 3 below.

  As can be seen from Table 3, both n-butyl levulinate and n-pentyl levulinate have better miscibility with fuel C than ethyl levulinate. For example, in 5% by volume of ethyl levulinate, the phase separation temperature was 5 ° C., but in 5% by volume of n-butyl levulinate or 5% by volume of n-pentyl levulinate, the phase separation temperature was less than −30 ° C. . Note that at concentrations of n-butyl levulinate of 8-10 vol% and concentrations of n-pentyl levulinate of 10 vol% or less, even severe Swedish Class 1 AGO remained in solution at temperatures below -20 ° C. It is to be done.

  The miscibility test was repeated using fuel B, and the above findings were confirmed in the conventional European EN590 standard diesel fuel. These results are shown in Table 4.

  As can be seen from Table 4, both n-butyl levulinate and n-pentyl levulinate have better miscibility with fuel B than ethyl levulinate having a concentration of 4% by volume or more. For example, 5% by volume of ethyl levulinate had a phase separation temperature of −10 ° C., but 5% by volume of n-butyl levulinate or 5% by volume of n-pentyl levulinate had a phase separation temperature of −27 ° C. It was. At concentrations below 10% by volume n-butyl levulinate and below 10% by volume n-pentyl levulinate, the solution remains at a temperature below −20 ° C. and the wax cloud point before phase separation is observed. It is notable that we have reached.

Example 2
Effect of alkyl levulinate on fluorocarbon elastomer swelling:
The effect of various alkyl levulinates on elastomer seals was evaluated by a test method based on ISO 1817: 1998. The volume and average Shore hardness of a nominal 50 mm × 25 mm × 3 mm thick elastomer sample were measured before and after immersion in 100 ml of test fuel at ambient temperature (20 ° C.) for 168 hours. The sample was then removed from the test solution, the surface was quickly dried, weighed in air and water, and new volume and hardness were measured within 8 hours after removal from the test medium. Hardness was measured at ambient temperature using a type A Shore indentation hardness meter (Shor Instruments, USA). Next, the change rate of the volume and average hardness due to immersion in the test fuel was determined for each sample.

  Tests were conducted to compare the effects of ethyl levulinate, n-butyl levulinate, n-pentyl levulinate and 2-hexyl levulinate on elastomers. Each of these compounds was blended at a concentration of 5% by volume into a conventional diesel fuel, Fuel D base fuel sample. Table 5 shows the characteristics of fuel D and a blend of 5% by volume n-pentyl levulinate to fuel D.

The elastomeric material is LR 6316 (a fluorocarbon tetrapolymer also known as Viton ™) (UK James Walker & Co, UK) to represent seals (eg, O-rings, etc.) used in modern diesel fuel systems. Obtained from Ltd.). This material is a common elastomeric material used in modern diesel fuel systems and is less susceptible to seal swell than other elastomeric materials, but has been selected as an elastomeric material that can make noticeable changes in swelling characteristics. .
The effects of various levulinate esters on the volume and hardness of the LR 6316 fluorocarbon elastomer sample are summarized in Table 6.

  N-butyl levulinate, n-pentyl levulinate and 2-hexyl levulinate have substantially less seal swell (ie volume change%) than ethyl levulinate, and n-butyl levulinate, n-levulinate It can be seen that the hardness change due to pentyl and 2-hexyl levulinate is substantially less than that of ethyl levulinate and not much different from conventional fuel D.

The ISO 1817 standard states that "no direct correlation with usage behavior is implied" and therefore a "pass / fail" limit cannot be defined without mentioning the end use. However, if it is considered that a fuel or a fuel additive having a seal swelling degree of 2% or less due to LR 6316 fluorocarbon elastomer is less likely to cause a problem in use, as can be seen from Table 6, n-pentyl levulinate and levulinic acid 2 -Hexyl is the preferred levulinate ester.

Claims (8)

A fuel composition comprising a gas oil base fuel and an alkyl levulinate, said alkyl levulinate is levulinic acid C _4-8 alkyl, the composition phase separation temperature of the fuel composition is less than -10 ° C. . C _4-8 alkyl _levulinate is used as the alkyl levulinate in the fuel composition for the purpose of ensuring the phase separation temperature of the fuel composition containing the gas oil base fuel and the alkyl levulinate to less than −10 ° C. how to.   The fuel composition according to claim 1 or the use according to claim 2, wherein the phase separation temperature is less than -30 ° C.   The fuel composition according to claim 1 or the use according to claim 3, wherein the alkyl levulinate is selected from n-butyl levulinate, n-pentyl levulinate and 2-hexyl levulinate. A method for lowering the phase separation temperature of a fuel composition, wherein at least a part of ethyl levulinate in a fuel composition containing a gas oil base fuel and ethyl levulinate is substituted with C _4-8 alkyl levulinate. . Compression ignition engine and / or operating method of a motor vehicle for a compression ignition engine powered and introducing the fuel composition of claim 1 into the combustion chamber of a compression ignition engine.   A method for operating the heating apparatus, wherein the fuel composition according to claim 1 is supplied to a burner of a small heating apparatus having a burner. The method for producing a fuel composition according to claim 1, wherein a gas oil base fuel and C _4-8 alkyl levulinate are blended.