Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/04—Liquid carbonaceous fuels essentially based on blends of hydrocarbons
  • C10L1/08—Liquid carbonaceous fuels essentially based on blends of hydrocarbons for compression ignition

Definitions

• the present invention relates to a diesel fuel composition. More specifically, it relates to a diesel fuel composition with superior oxidation stability while being constituted essentially only of paraffins.
• FT fuels are fuels obtained by synthesis from raw materials such as natural gas, coal or biomass, using the Fischer-Tropsch process via synthesis gas, a mixture of carbon monoxide and hydrogen. They are often used under names corresponding to the raw material. For example, for those where natural gas is the raw material the name GTL is often used, if coal is the raw material the name CTL may be used, and if biomass is the raw material, the name BTL may be used.
• GTL is also sometimes used as a generic name for fuels obtained by the Fischer-Tropsch process, but in the present invention the term FT fuels is used for fuels obtained by the Fischer-Tropsch process and FT fuels are deemed to include GTL, CTL and BTL.
• these FT fuels are expected to be used as alternatives to petroleum because they are synthesised from raw materials such as natural gas, coal and biomass and also, because they do not contain sulphur or aromatic hydrocarbons, they are expected to be used as diesel fuels which are better for the environment, in that they limit the emission of sulphur oxides and particulate matter (PM) from engines. They have already been made available commercially in some areas, as reported for example in “The marketability of liquid fuels from natural gas (GTL)”, [Energy Economics], November 2001 issue.
• oxidation stability is an important indicator for evaluation of the qualitative stability of a diesel fuel, and it is desirable for a diesel fuel to have superior oxidation stability.
• diesel engines have been equipped with common rail fuel injection systems as a means of reducing particulates (or particulate matter, referred to below as PM) in exhaust gases.
• oxidation stability of diesel fuels it is widely and generally known that oxidation stability can be improved by the addition of amine-based and phenol-based anti-oxidants of various kinds, and there have been attempts to add oxidation stabilisers also to the fractions corresponding to the diesel oils of FT fuels (referred to below as FT diesel oils).
• FT diesel oils FT diesel oils
• JP-A-2008-214369 JP-A-2008-214369.
• GTL diesel fuel GTL fuel
• the amount of anti-oxidant required in order to obtain the desired effect becomes large for fuels that have poor oxidation stability and production costs are raised.
• JP-A-2008-266617 has, therefore, proposed maintaining the oxidation stability of diesel fuels without adding anti-oxidants.
• at least one kind of polycyclic aromatic compound selected from the group comprised of anthracenes and dialkylnaphthalenes is blended with an FT diesel oil to ensure oxidation stability.
• the aim of the present invention is to offer a diesel fuel composition with superior oxidation stability while being constituted essentially only of paraffins.
• the diesel fuel composition according to the present invention essentially comprises only paraffins, and is characterised in that
• the normal paraffins with 18 or fewer carbons constitute not less than 12% by mass, and 2) the proportion of the total peak area of the peak group at chemical shifts of 1.45 to 2.25 ppm relative to the total peak area of the peak group at chemical shifts of 1.00 to 1.45 ppm is less than 6.5% in proton nuclear magnetic resonance ( 1 H-NMR) spectra, and satisfies the condition that the oxidation index OI represented by the following equation is less than 1.10:
• X is the proportion (%) of the total peak area of the peak group at chemical shifts of 1.45 to 2.25 ppm relative to the total peak area of the peak group at chemical shifts of 1.00 to 1.45 ppm in proton nuclear magnetic resonance ( 1 H-NMR) spectra; and Y is the content (mass %) of normal paraffins with 18 or fewer carbons.
• the normal paraffins with 18 or fewer carbons are less than 12% by mass, if the proportion of the total peak area of the peak group at chemical shifts of 1.45 to 2.25 ppm relative to the total peak area of the peak group at chemical shifts of 1.00 to 1.45 ppm is 6.5% or more in proton nuclear magnetic resonance ( 1 H-NMR) spectra, or if the oxidation index OI is 1.10 or more, because then the oxidation stability is impaired. To increase the oxidation stability even further, it is preferable if the oxidation index OI is less than 0.9, and more preferably less than 0.7.
• the diesel fuel composition relating to the present invention may also be such that the increase in the total acid number between before and after an oxidation stability test is not more than 1.3 mg KOH/g.
• the preferred increase in the total acid number between before and after an oxidation stability test is 1.0 mg KOH/g, but more preferably 0.9 mg KOH/g.
• an oxidation stability test in the present invention is an oxidation test performed as in ASTM D2274 under conditions of oxygen bubbling for 16 hours but with the test temperature changed to 115° C.
• paraffins are essentially composed only of paraffins.
• the main constituent does not contain styrene compounds or diene compounds, or condensed polycyclic aromatics. Containing compositions of other than paraffins as impurities is tolerated.
• an FT diesel oil in which the total mass or volume of isoparaffins and normal paraffins is not less than 99% of the whole, excluding tiny impurities, is a diesel fuel composition constituted essentially only of paraffins suitable for the present invention.
• suitable additives within a range that does not go beyond the scope of the present invention, for example a range that does not cause the problems of cost or separation in the prior art.
• lubricity improvers to prevent wear of, for example, fuel feed-pump parts. It is also possible to use, as the lubricity improvers, any known lubricity improvers provided they are miscible in paraffins.
• Typical lubricity improvers are commercial acid-based lubricity improvers which have fatty acids as their main constituent, and ester-based lubricity improvers which have as their main constituent glycerin mono fatty acid esters. These compounds may be used singly or in combinations of two or more kinds.
• the fatty acids used in these lubricity improvers are preferably those that have as their main constituent a mixture of unsaturated fatty acids of approximately 12 to 22 carbons, but preferably about 18 carbons, that is oleic acid, linolic acid and linolenic acid.
• the lubricity improver may be added so that the wear scar WS 1.4 value in an HFRR (High Frequency Reciprocating Rig) of the fuel composition after addition of the lubricity improver is not more than 500 ⁇ m, but preferably not more than 460 ⁇ m, and the amount thereof is usually 50 to 1000 ppm.
• the WS 1.4 value in an HFRR here refers to the value obtained in accordance with the Japanese Petroleum Institute standard JPI-5S-50-98 “Gas oil—Method for testing lubricity”.
• additives such as amine salts of alkenyl succinate derivatives, metal deactivators such as salicylidene derivatives, de-icing agents such as polyglycol ethers, rust inhibitors such as aliphatic amines and alkenyl succinate esters, anti-static agents such as anionic and cationic amphoteric surfactants, and silicone-based defoaming agents.
• detergents such as amine salts of alkenyl succinate derivatives, metal deactivators such as salicylidene derivatives, de-icing agents such as polyglycol ethers, rust inhibitors such as aliphatic amines and alkenyl succinate esters, anti-static agents such as anionic and cationic amphoteric surfactants, and silicone-based defoaming agents.
• detergents such as amine salts of alkenyl succinate derivatives, metal deactivators such as salicylidene derivatives, de-icing agents such as polyglycol ethers,
• Low-temperature flow characteristics are required of diesel fuel compositions, to take account of use during winter or in cold regions. From the standpoint of improving these low-temperature flow characteristics, it is generally preferable if there are more iso-paraffins. On the other hand, from the standpoint of oxidation stability it is preferable to have more normal paraffins. In other words, low-temperature flow characteristics and oxidation stability show opposing behaviours in the composition. However, because it is possible to improve low-temperature flow characteristics by means of additives, it is possible to achieve improvement in oxidation stability while taking low-temperature flow characteristics into account by suitable use of additives.
• low-temperature fluidity improvers it is possible to use any known low-temperature fluidity improvers provided they are miscible with paraffins.
• Typical low-temperature fluidity improvers are commercial low-temperature fluidity improvers such as ethylene-vinyl acetate copolymers, ethylene-alkylacrylate copolymers, alkenyl succinamides, chlorinated polyethylenes, or polyalkyl acrylates. These compounds may be used singly or in combinations of two or more kinds. Of these, ethylene-vinyl acetate copolymers and alkenyl succinamides are especially preferred.
• the amount of the low temperature fluidity improver for example a suitable amount may be blended in so as to satisfy the pour points and cold filter plugging points specified in JIS K 2204, which is the JIS standard for diesel fuel, but normally the amount will be 50 to 1000 ppm.
• the pour point here refers to the pour point obtained in accordance with JIS K 2269 “Testing methods for pour point and cloud point of crude oil and petroleum products”
• the cold filter plugging point refers to the cold filter plugging point obtained by JIS K 2288 “Petroleum products—Diesel fuel—Determination of cold filter plugging point”.
• the following base materials were used to produce diesel fuel compositions comprising hydrocarbon fuel oils and FT fuels comprised only of polykerosene (paraffin) base materials, being oil mixtures with adjusted distillation characteristics and compositions.
• Table 1 shows the characteristics of the base materials, while Tables 2 and 3 show the characteristics and compositions of the diesel fuel compositions obtained.
• Table 3 also shows an FT fuel of the prior art as a reference example.
• Base material A base material B (synthetic paraffins): Taking as the raw materials by-product gases (butane and butylene fractions) which have as their main constituent light hydrocarbons with a carbon number of 4 obtained, for example, from fluid catalytic cracking apparatus and thermal cracking apparatus during petroleum refining, an oligomerisation treatment was carried out by means of the IFP/Axens Polynaphtha process, and after conversion selectively to hydrocarbon fractions of 10 to 24 carbons, paraffin base materials with differing distillation characteristics and compositions were obtained via desulphurisation, hydrogenation treatment of olefins and the distillation process.
• by-product gases butane and butylene fractions
• Base material C, base material D, base material E, base material F, base material G natural gas was partially oxidised by means of the SMDS (Shell Middle Distillate Synthesis) process, and after synthesising the syngas derived from carbon monoxide and hydrogen (CO+H 2 ) to a waxy straight-chain alkyl hydrocarbon by means of a Fischer-Tropsch reaction, hydrocracking and isomerisation were carried out over a catalyst, and base materials being mixtures of normal paraffins and isoparaffins with differing distillation characteristics and compositions were obtained.
• SMDS Shell Middle Distillate Synthesis
• Density at 15° C. measured in accordance with JIS K 2249 “Crude oil and petroleum products—Determination of density and density/mass/volume conversion tables”.
• the type of column in the gas chromatography was HP5 (length: 30 m, inside diameter: 0.32 mm, liquid layer thickness: 0.25 ⁇ m), and the analysis conditions were as follows.
• the oxidation stability test of Examples 1 to 6 the Comparative Example and the Reference Example
• the increment in the total acid number between before and after the acceleration test was measured (referred to below as the acid number).
• the oxidation stability test was performed in accordance with ASTM D2274 at 115° C. under conditions of oxygen bubbling for 16 hours. These results, too, are shown in Tables 4 and 5.
• the total acid number was measured in accordance with JIS K 2501 “Petroleum products and lubricants—Determination of neutralisation value”.
• X is the proportion (%) of the total peak area of the peak group at chemical shifts of 1.45 to 2.25 ppm relative to the total peak area of the peak group at chemical shifts of 1.00 to 1.45 ppm in proton nuclear magnetic resonance ( 1 H-NMR) spectra; and Y is the content (mass %) of normal paraffins with 18 or fewer carbons).

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• Chemical & Material Sciences (AREA)
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• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Liquid Carbonaceous Fuels (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)

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• 2008
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