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 an essentially hydrocarbon composition having enhanced lubricating properties.
• the present invention relates to a hydrocarbon composition which can be used as a fuel, especially for Diesel-type engines, which has surprisingly enhance lubricating properties with respect to the single original components, and maintains however a high cetane number and a reduced presence of aromatics.
• Fuels for Diesel engines are characterized by various properties associated both with their performances in the combustion phase and also with their cold flow properties and lubrication.
• These lubricating properties are usually measured by means of specific empirical methods well known to experts in the field, such as the indication of the so-called lubricity according to the HFRR method (regulation CEC-F-06-A-96), to which reference is made hereunder in the present description.
• F.T. Fischer-Tropsch type
• Processes of the Fischer-Tropsch type are known to be processes which allow gaseous mixtures containing hydrogen and carbon monoxide in ratios varying from 2/1 to 4/1 (syn-gas) to be converted into liquid or solid mixtures of essentially linear hydrocarbons, sometimes partially oxygenated.
• F.T. processes i.e. in general the direct synthesis of organic hydrocarbon or oxygenated products starting from suitable mixtures of hydrogen and carbon monoxide, in the presence of appropriate catalysts, specifically called F.T. catalysts.
• Typical F.T. catalysts for obtaining prevalently paraffinic products with medium-high distillation ranges are based on cobalt or iron, generally supported on inert oxides such as alumina, silica and their mixtures.
• the molecular weight distribution in these liquid mixtures extends to a range of values which vary according to the catalyst and process conditions.
• paraffinic products obtained from the Fischer-Tropsch synthesis reactor are subsequently subjected to hydrogenating and/or isomerizing treatment (hydro-isomerization, hydrotreating, hydrocracking) in the presence of suitable catalysts, followed by fractionation by distillation to obtain fuel cuts within the desired range, usually medium distillates, i.e. gas oil and/or kerosene, commonly called Diesel Fuel and Jet Fuel.
• hydrogenating and/or isomerizing treatment hydro-isomerization, hydrotreating, hydrocracking
• suitable catalysts followed by fractionation by distillation to obtain fuel cuts within the desired range, usually medium distillates, i.e. gas oil and/or kerosene, commonly called Diesel Fuel and Jet Fuel.
• cuts (or fractions) deriving from F.T. processes therefore usually consist of mixtures of essentially paraffinic hydrocarbons, with distillation ranges (according to the publications) from 150-180 to 230-250 for Jet Fuel and from 230-260 to 360-380 for Diesel, wherein from 60 to 90% of the molecules have prevalently methyl branchings.
• Possible unsaturations or oxygenated groups typically present in a quantity ranging from 5 to 10% by weight in the Fischer-Tropsch synthesis product, are normally removed during the treatment with hydrogen mentioned above.
• Diesel cuts deriving from F.T. which can be used as blending stocks suitable for improving the combustible properties and having high lubricating properties, are described in U.S. patent 5,689,031 .
• These hydrocarbon mixtures comprise a significant portion of oxygenated compounds and are obtained by means of a complex process which includes the separation of a fraction which is not subjected to hydrogenating treatment and subsequently joined to the remaining fraction subjected to hydro-isomerization.
• the diesel cut thus obtained has improved lubricating properties, its low temperature properties are not entirely satisfactory, and a costly and complex process is also required for its production.
• WO 01/83406 relates to a blended fuel, useful as diesel fuel, containing an undercut conventional diesel fuel and a FT derived diesel fuel.
• WO 00/20535 relates to middle distillates having good cold flow properties, produced from a mainly paraffinic synthetic crude which is produced by the reaction of CO and H 2 , typically by the Fischer-Tropsch process.
• the Applicant has now surprisingly found that by adding small quantities of a synthetic cut essentially without organic oxygen, deriving from a synthesis process of the Fischer-Tropsch type, to a traditional refinery medium distillate, especially gas oil, it is possible to obtain a combustible hydrocarbon composition having a higher lubricating capacity than that obtained from each of the original components, and also, with respect to the medium distillate, a much higher cetane number and an improved quality of the combustion emissions of an engine fed therewith.
• a first object of the present invention therefore relates to the use of a synthetic hydrocarbon mixture as defined in claim 1.
• Component (A) of the present composition can consist of any refinery hydrocarbon mixture having the characteristics specified above. Among these, those most suitable for use as fuels for engines are preferred, even though mixtures suitable for other uses are not excluded from the scope of the present invention. Hydrocarbon mixtures having a distillation range comprised within 200 to 370°C, particularly any non-synthetic gas oil fraction ranging from 240 to 360°C, are especially preferred.
• Said mixtures of component (A) generally consist of aliphatic, naphthene and aromatic hydrocarbons with varying structures and isomerization degrees, prevalently having a number of carbon atoms greater than 8 and up to about 30.
• Compounds containing hetero-atoms such as S, O, N, can also be present to a varying extent.
• Refinery distillates containing the minimum possible quantity of hetero-atoms are however particularly suitable for the present invention, in accordance with the increasingly strict regulations aimed at reducing problems relating to the environmental impact of fuels.
• the lubricating properties of these products in fact, progressively deteriorate with a decrease in the sulfur content, and have lubricity values corresponding to average diameters higher than 460 ⁇ m measured with the above HFRR method.
• Typical but non-limiting examples of essentially hydrocarbon mixtures or fractions which can be used as component (A) in the compositions of the present invention are, for example, gas oil and kerosene from primary distillation, gas oil and kerosene from desulfuration processes, gas oil from hydrocracking, gas oil from catalytic dewaxing.
• Component (B) consists of a hydrocarbon mixture essentially without aromatic compounds and sulfur, and whose content of oxygenated compounds is lower than the minimum level which can be detected with the usual analytic methods, such as IR or NMR spectroscopy and gas-mass spectrometry.
• Said hydrocarbon mixture essentially consists of a mixture of linear and branched paraffins and is obtained by subjecting the product of an F.T. synthesis or a part thereof, to hydrogenating/isomerization treatment.
• the latter product is usually characterized by a substantial absence of sulfur and preferably consists of over 70% by weight of linear paraffins having more than 15 carbon atoms.
• F.T. products are frequently solid or semi-solid at room temperature and for this reason are called waxes.
• Not all F.T. synthesis processes provide high-boiling mixtures of linear paraffins.
• the Fischer-Tropsch process can produce mixtures having different distillation temperature ranges, also relatively low if desired. It has proved to be more convenient however to carry out the process so as to prevalently obtain high-boiling mixtures or waxes, which can then be suitably degraded ad fractionated into the desired distillation cuts.
• F.T. processes produce hydrocarbon mixtures containing oxygenated hydrocarbons, normally in the form of alcohols, whose content can generally reach a maximum of 10% by weight with respect to the total.
• these oxygenated compounds mainly consist of alcohols with a linear chain, but can also comprise acids, esters and aldehydes in much lower concentrations ( The Fischer Tropsch and Related Syntheses, H.H. Storch, N. Golumbic, R.B. Anderson, John Wiley & Sons, Inc., N.Y. 1951 ).
• the hydrogenating treatment is such as to hydrogenate the unsaturated and oxygenated groups, but not significantly reduce the average molecular weight.
• Experts in the field can decide whether to also apply a hydrogenating/isomerizing treatment according to what is known in the art, in order to give satisfactory low temperature properties, either as a subsequent step to the hydrogenation of the oxygenated groups, or contemporaneously with this in the presence of suitable hybrid catalysts, i.e. containing both hydrogenating functions (supported noble metals), and isomerizing functions (acid sites).
• the F.T. product comprises significant parts of waxy high-boiling products
• it is typically subjected to an upgrading process comprising one or more hydrocracking steps, optionally preceded by a hydrogenation step.
• a hydrocracking step is carried out in the presence of a bifunctional catalyst, containing a metal with a hydro-dehydrogenating activity supported on an inorganic solid comprising at least one oxide or silicate with acid characteristics.
• Hydrocracking catalysts typically comprise metals of groups 6 to 10 of the periodic table of elements (in the form approved by IUPAC and published by "CRC Press Inc.” in 1989 , to which reference will be made hereunder), especially nickel, cobalt, molybdenum, tungsten or noble metals such as palladium or platinum. Whereas the former are more suitable for processing hydrocarbon mixtures with relatively high sulfur contents, noble metals are more active, but are poisoned by sulfur and other hetero-atoms and are therefore particularly suitable for processing hydrocarbon mixtures of the type obtained by means of F.T.
• Carriers which can normally be used for the purpose are various types of zeolites ( ⁇ , Y), X-Al 2 O 3 (wherein X can be Cl or F), silico-aluminas, the latter being amorphous or with varying degrees of crystallinity, or mixtures of crystalline zeolites and amorphous oxides.
• zeolites ⁇ , Y
• X-Al 2 O 3 wherein X can be Cl or F
• silico-aluminas the latter being amorphous or with varying degrees of crystallinity, or mixtures of crystalline zeolites and amorphous oxides.
• patent application EP-A 321,303 (Shell) describes a process which comprises the separation of the light fraction (290-°C, rich in oxygenated compounds) of a hydrocarbon mixture from an F.T. process, and sending the 290+°C fraction to a hydrocracking/isomerization reactor for the production of medium distillates.
• the catalyst claimed for both reactors consists of platinum supported on fluorinated alumina.
• European patent application EP-A 1101813 describes an upgrading process of a waxy F.T. product comprising a hydrogenating treatment step mainly aimed at removing the organic oxygen and unsaturations in the olefins and, if necessary, the partial isomerization of the lighter part of the product, typically carried out at a temperature ranging from 150 to 300°C, a hydrogen pressure ranging from 0.5 to 10 MPa and a space velocity (WHSV) ranging from 0.5 to 4 h -1 , with a hydrogen/filler ratio ranging from 200 to 2000 Nlt/Kg.
• WHSV space velocity
• the hydrogenation catalyst is based on nickel, platinum or palladium, supported on alumina, silico-alumina, fluorinated alumina, with a concentration of the metal which, depending on the type, ranges from 0.1 to 70%, preferably from 0.5 to 10%, by weight.
• the hydrogenated mixture is subsequently subjected to hydrocracking effected so as to provide a conversion degree of at least 50% and produce a medium distillate cut with high conversions and selectivities.
• the catalyst used for the purpose preferably consists of a noble metal, particularly Pt or Pd, supported on an amorphous silica-alumina gel and micro/mesoporous with a controlled pore size, a surface area of at least 500 m 2 /g and a molar ratio SiO 2 /Al 2 O 3 ranging from 40/1 to 150/1, obtained according to one of the methods described in European patent applications EP-A 582,347 , EP-A 701,480 or EP 1,048,346 , whose contents are incorporated herein as reference.
• the hydrocracking reaction mixture is sent to a distillation/separation step from which, operating according to the known art, a medium distillate is obtained, subdivided into gas oil and kerosene fractions, both suitable, but especially the gas oil fraction, as component (B) of the composition according to the present invention.
• the F.T. hydrocarbon mixture which forms component (B) preferably comprises not less than 50%, more preferably from 60 to 90%, by weight of branched aliphatic hydrocarbons, of which at least 60% has a methyl branching, as determined with the gas-mass and NMR instrumental techniques currently available.
• Other preferred characteristics of this mixture are:
• the proportions of components (A) and (B) preferably range from 85 to 98% by weight and from 15 to 2% by weight respectively with respect to the overall weight of the two components. These together form from 80 to 100%, preferably from 90 to 100% by weight of the composition according to the present invention, the remainder optionally consisting of additives and smaller quantities of other components typically used in the preparation of fuels and combustibles according to the usual technique.
• the composition can be easily prepared by mixing components (A) and (B) indicated above, in the suitable proportions. Any suitable method in the art can be adopted for the purpose, and there are no particular critical operating conditions.
• the composition can be obtained for example by batch mixing in suitable containers, or, more conveniently, in continuous, as normally happens within the scope of refinery processing.
• components (A) and (B), in appropriate proportions are poured into a container and briefly mixed at room temperature until they are homogeneously dispersed in each other.
• the optional additives can be added, when desired, to the preformed mixture of (A) and (B), or they can be already present, in suitable quantities, in one or both of the components at the moment of mixing, preferably in component (A).
• compositions show, as such, evident improvement in the lubricants properties, this does not exclude that they can also contain certain quantities of known additives for improving the lubricity. In this case, it has been found that the lubricating properties of the composition are however surprisingly improved with respect to a mixture consisting of component (A) alone with the same quantity of additive.
• compositions can comprise up to 20%, preferably up to 10% by weight with respect to the total weight, of one or more additives usually used in the art for giving certain desired properties to compositions to be used as fuels, such as viscosity improvers, anti-freeze agents, additives for improving the combustion, such as cetane improvers and octane improvers.
• additives usually used in the art for giving certain desired properties to compositions to be used as fuels, such as viscosity improvers, anti-freeze agents, additives for improving the combustion, such as cetane improvers and octane improvers.
• these additives can be indifferently added to the preformed mixture of components (A) and (B), or each additive can be independently added or contained in one of components (A) and (B), or again, said additives can be added, in any order, during and contemporaneously with the mixing of said components (A) and (B) .
• the present invention therefore relates to the use for improving the lubricating capacity (lubricity) of a fuel for engines, of a synthetic hydrocarbon mixture essentially without oxygenated organic compounds, as defined in claim 1 having a distillation range comprised within 130 and 380°C, preferably within 150 and 370°C, more preferably within 240 and 370°C, wherein said synthetic hydrocarbon mixture is added to said fuel, in a quantity ranging from 1 to 25% by weight with respect to the fuel itself.
• said fuel is particularly suitable for use in diesel engines and essentially has the characteristics of the refinery hydrocarbon mixture forming component (A) described above.
• the above fuel can also contain, according to the present invention, one or more of the typical additives of fuels defined within the medium distillate range, as mentioned above. These additives do not generally exceed 20% by weight of the fuel.
• the method in question comprises the addition and mixing with said fuel of a hydrocarbon mixture deriving from a Fischer-Tropsch synthesis, having a distillation range substantially overlapping that of the fuel.
• the lubricating properties of the compositions described in the examples were evaluated by means of a lubricity measurement according to the HFRR (high frequency reciprocating rig) method.
• This method developed at the Mechanical Engineering Department of London Imperial College has been recognized as being among the most qualified for the lubricating capacity or lubricity measurement of a composition suitable for use as a fuel, and is well known by experts in the field. The equipment for effecting this measurement is available on the market.
• the equipment for effecting the measurement according to the HFRR method consists in an upper sphere loaded with a standard weight which oscillates against a lower static plate.
• the contact is totally immersed in the fuel on which the measurement is being effected.
• the friction and electric resistance of the contact are registered and the diameter of the wear trace on the sphere at the end of the test, is measured.
• a measuring instrument supplied by the company PCS Ltd. of London (UK) was used, with a load of 200 g on an AISI E-52100 steel sphere having a diameter of 6 mm, which oscillates on a plate made of the same material.
• the measurement is effected on a 2 ml sample of fuel composition at 60°C.
• a synthesis gas oil suitable as component (B) according to the present invention was prepared, using a waxy product deriving from a Fischer-Tropsch process, essentially consisting of linear hydrocarbons according to the following composition (weight %): Fraction ⁇ 150°C 4.9 Kerosene (from 150 to 260°C) 13.9 Gas oil (from 260 to 370°C) 25.8 Fraction > 370°C 55.4 Alcohols (weight %) 4.7 Sulfur and aromatics absent
• Three hydrocarbon compositions with an improved lubricity were prepared, to be used as fuel for diesel engines, by mixing different proportions of the following two components: A) a refinery gas oil cut called "Gas oil A", having the following characteristics: HFRR, wear diameter ( ⁇ m) 407 sulfur (weight %) 0.8 density at 15°C 0.8491 aromatics (weight %) 25.2 distillation range (°C) 230-370 B) an essentially paraffinic hydrocarbon mixture consisting of "Gas oil FT" obtained according to the above Preparative Example.
• Gas oil A a refinery gas oil cut having the following characteristics: HFRR, wear diameter ( ⁇ m) 407 sulfur (weight %) 0.8 density at 15°C 0.8491 aromatics (weight %) 25.2 distillation range (°C) 230-370
• compositions thus obtained are indicated as (i), (ii) and (iii) respectively, are indicated in Table 1 below, together with the relative proportions of components (A) and (B).
• hydrocarbon compositions with an improved lubricity were prepared, to be used as fuel for diesel engines, by mixing different proportions of the following two components: A) a refinery gas oil cut called "Gas oil B", having the following characteristics: HFRR, wear diameter ( ⁇ m) 505 sulfur (weight %) 0.023 density at 15°C 0.8429 aromatics (weight %) 30.4 distillation range (°C) 230-370 B) an paraffinic hydrocarbon mixture consisting of "Gas oil FT" obtained as described above.
• Gas oil B a refinery gas oil cut having the following characteristics: HFRR, wear diameter ( ⁇ m) 505 sulfur (weight %) 0.023 density at 15°C 0.8429 aromatics (weight %) 30.4 distillation range (°C) 230-370
• compositions thus obtained are indicated as (i), (ii), (iii) and (iv) respectively, are indicated in Table 1 below, together with the relative proportions of components (A) and (B).
• Three hydrocarbon compositions with an improved lubricity were prepared, to be used as fuel for diesel engines, by mixing different proportions of the following two components: A) a refinery gas oil cut called "Gas oil C", having the following characteristics: HFRR, wear diameter ( ⁇ m) 675 sulfur (weight %) 0.0047 density at 15°C 0.7971 aromatics (weight %) 8.8 distillation range (°C) 230-310 B) an paraffinic hydrocarbon mixture consisting of "Gas oil FT" obtained as described above.
• compositions thus obtained are indicated as (i), (ii) and (iii) respectively, are indicated in Table 1 below, together with the relative proportions of components (A) and (B).
• the compositions all have a surprisingly improved lubricity (lower HFRR wear diameter values) with respect to the lubricity of both of the original components A and B.
• the improvement in lubricity is such as to allow specification values to be reached (HFRR ⁇ 450 ⁇ m) even though both of the original components have higher HFRR values (505 ⁇ m and 607 ⁇ m respectively).
• Table 1 Gas oil compositions with an improved lubricity Composition
• Example 1 Example 2
• Example 3 "Gasoil A” (wt%) Gasoil FT (wt%) HFRR ( ⁇ m) "Gasoil B” (wt%) Gasoil FT (wt%) HFRR ( ⁇ m) "Gasoil C” (wt%) Gasoil FT (wt%) HFRR ( ⁇ m) Refinery gas oil alone 100 0 407 100 0 505 100 0 675 (i) 95 5 360 98 2 436 95 5 589 (ii) 90 10 330 90 10 444 90 10 597 (iii) 80 20 330 85 15 457 80 20 606 (iv) - - - 80 20 466 - - - -

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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Liquid Carbonaceous Fuels (AREA)

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• 2002
  • 2002-05-24 IT IT2002MI001131A patent/ITMI20021131A1/it unknown
• 2003
  • 2003-05-20 EP EP03076501.0A patent/EP1365007B9/en not_active Expired - Lifetime
  • 2003-05-20 ZA ZA200303912A patent/ZA200303912B/xx unknown
  • 2003-05-22 US US10/443,095 patent/US20040030205A1/en not_active Abandoned
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