Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G67/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only
  • C10G67/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only
  • C10G67/04—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only including solvent extraction as the refining step in the absence of hydrogen
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
  • C10G65/02—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only
  • C10G65/04—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including only refining steps
  • C10G65/043—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including only refining steps at least one step being a change in the structural skeleton
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/10—Lubricating oil

Definitions

• the present invention relates to a process for producing lubricating base oils from Fischer-Tropsch waxes, and in particular lubricating base oils having a viscosity index (VI) of at least 150.
• VI viscosity index
• a process for producing lubricating base oils having a VI of at least 130 from Fischer-Tropsch waxes, in which process the wax is first hydrotreated under severe conditions, then the hydrotreated wax is hydro-isomerised by contacting it with a fluorided Group VIII (noble) metal-on-alumina catalyst, subsequently the effluent from the hydro-isomerisation step is fractionated to produce a lubricating oil fraction and finally this lubricating oil fraction is dewaxed to produce the desired lubricating base oil. Unconverted wax recovered in the final dewaxing step may be recycled to the hydro-isomerisation step.
• a fluorided Group VIII (noble) metal-on-alumina catalyst subsequently the effluent from the hydro-isomerisation step is fractionated to produce a lubricating oil fraction and finally this lubricating oil fraction is dewaxed to produce the desired lubricating base oil.
• Unconverted wax recovered in the final dewaxing step may
• the Fischer-Tropsch wax used should be a high boiling wax, since it is the intention to convert in the severe hydrotreating step that material present in the wax that has a boiling point above about 565 °C.
• a Fischer-Tropsch wax is used which was obtained as the 370 °C+ fraction from the distillation of a Fischer-Tropsch synthesis product. Accordingly, the waxes used as the feedstocks are relatively high boiling waxes having a broad boiling range and a large heavy tail.
• the fractionation after the hydroisomerisation step, or -if applied- after the hydrofinishing step should remove both the lightest fraction (boiling below 338 °C) and the heaviest fraction (boiling above 538 °C) from the hydroprocessed wax in order to obtain a final base oil product having acceptable volatility properties.
• the wax used as the feed may be a synthetic wax from a Fischer-Tropsch process or could be a slack wax obtained from a dewaxing process. No specific demands are made upon the Fischer-Tropsch waxes to be useful as a feed in the process disclosed.
• the Fischer-Tropsch wax used in Example 1 of US-A-5,059,299 is a high boiling wax having a relatively broad boiling range, which, as has already been stated above, results in the base oil product having unacceptable volatility properties.
• the isomerisation catalyst used suitably comprises a hydrogenating component on a halogenated refractory oxide support.
• the preferred catalyst is disclosed to be platinum on fluorided alumina.
• the present invention aims to provide such improved process. More specifically, the present invention aims to provide a process for preparing base oils having a VI of at least 150 from a Fischer-Tropsch wax, which process involves a single hydroprocessing stage and a fractionation stage, wherein only the lighter components need to be removed from the hydroprocessed effluent. Furthermore, it is an object of the present invention to provide base oils having excellent properties, particularly in terms of VI and volatility, at commercially attractive yields.
• the present invention relates to a process for the preparation of lubricating base oils having a VI of at least 150 from a Fischer-Tropsch wax feed, which process comprises the steps of:
• the Fischer-Tropsch wax used as the feed for the present process is obtained via the well-known Fischer-Tropsch hydrocarbon synthesis process.
• Fischer-Tropsch hydrocarbon synthesis involves the preparation of hydrocarbons from a mixture of carbon monoxide and hydrogen at elevated temperature and pressure in the presence of a suitable catalyst.
• the Fischer-Tropsch catalyst normally is selective for preparing paraffinic molecules, mostly straight-chain paraffins, and the product from a Fischer-Tropsch synthesis reaction therefore usually is a mixture of a large variety of paraffinic molecules.
• Those hydrocarbons that are gaseous or liquid at room temperature are recovered separately, for instance as fuel gas (C 5 -), solvent feedstocks and detergent feedstocks (up to C 17 ).
• the more heavy paraffins (C 18 +) are recovered as one or more wax fractions, commonly referred to as Fischer-Tropsch wax(es) or synthetic wax(es).
• Fischer-Tropsch wax(es) or synthetic wax(es) are useful as the feed, which meet the aforementioned requirements with respect to their boiling range and congealing point.
• preferred Fischer-Tropsch wax feeds are those having a congealing point in the range of from 55 to 150 °C, preferably from 60 to 120 °C and/or such boiling range that the T 90 -T 10 is in the range of from 50 to 130 °C.
• Those Fischer-Tropsch waxes melting below 100 °C suitably have a kinematic viscosity at 100 °C (Vk100) of at least 3 mm 2 /s, preferably between 3 and 12 mm 2 /s, more preferably between 4 and 10 mm 2 /s.
• Fischer-Tropsch waxes melting above 100 °C suitably have a kinematic viscosity at a temperature T, which is 10 to 20 °C higher than their melting point, in the range of from 8 to 15 mm 2 /s, preferably from 9 to 14 mm 2 /s.
• the hydroconversion catalyst used in step (a) may in principle be any catalyst known in the art to be suitable for isomerising paraffinic molecules.
• suitable hydroconversion catalysts are those comprising a hydrogenation component supported on a refractory oxide carrier, such as amorphous silica-alumina, alumina, fluorided alumina, molecular sieves (zeolites) or mixtures of two or more of these.
• a refractory oxide carrier such as amorphous silica-alumina, alumina, fluorided alumina, molecular sieves (zeolites) or mixtures of two or more of these.
• One type of preferred catalysts to be applied in the hydroconversion step in accordance with the present invention are hydroconversion catalysts comprising platinum and/or palladium as the hydrogenation component.
• a very much preferred hydroconversion catalyst comprises platinum and palladium supported on an amorphous silica-alumina (ASA) carrier.
• ASA amorphous silica
• the platinum and/or palladium is suitably present in an amount of from 0.1 to 5.0% by weight, more suitably from 0.2 to 2.0% by weight, calculated as element and based on total weight of carrier. If both present, the weight ratio of platinum to palladium (calculated as element) may vary within wide limits, but suitably is in the range of from 0.05 to 10, more suitably 0.1 to 5.
• suitable noble metal on ASA catalysts are, for instance, disclosed in WO-A-94/10264 and EP-A-0,582,347.
• Other suitable noble metal-based catalysts, such as platinum on a fluorided alumina carrier are disclosed in e.g. US-A-5,059,299 and WO-A-92/20759.
• a second type of suitable hydroconversion catalysts are those comprising at least one Group VIB metal, preferably tungsten and/or molybdenum, and at least one non-noble Group VIII metal, preferably nickel and/or cobalt, as the hydrogenation component.
• both metals are present as oxides, sulphides or a combination thereof.
• the Group VIB metal is suitably present in an amount of from 1 to 35% by weight, more suitably from 5 to 30% by weight, calculated as element and based on total weight of catalyst.
• the non-noble Group VIII metal is suitably present in an amount of from 1 to 25 %wt, preferably 2 to 15 %wt, calculated as element and based on total weight of carrier.
• a hydroconversion catalyst of this type which has been found particularly suitable is a catalyst comprising nickel and tungsten supported on fluorided alumina.
• a third class of suitable hydroconversion catalysts are those based on an intermediate pore size zeolitic material, suitably comprising at least one Group VIII metal component, preferably Pt and/or Pd, as the hydrogenation component.
• Suitable zeolitic materials include ZSM-5, ZSM-22, ZSM-23, ZSM-35, SSZ-32, ferrierite, zeolite beta, mordenite and silica-aluminophosphates, such as SAPO-11 and SAPO-31.
• suitable hydroisomerisation catalysts are, for instance, described in WO-A-92/01657.
• the hydroconversion conditions applied in step (a) are those known to be suitable in hydro-isomerisation operations. Suitable conditions, then, involve operating temperatures in the range of from 275 to 450 °C, preferably 300 to 425 °C, a hydrogen partial pressure in the range of from 10 to 250 bar, suitably 25 to 200 bar, a weight hourly space velocity (WHSV) in the range of from 0.1 to 10 kg/l/h, preferably 0.2 to 5 kg/l/h, and a gas rate in the range of from 100 to 5,000 Nl/kg, preferably 500 to 3,000 Nl/kg.
• WHSV weight hourly space velocity
• step (b) of the present process the hydroconverted effluent from step (a) is separated into at least one lighter fraction and a heavy fraction.
• the effective cutpoint of the heavy fraction is suitably in the range of from 325 to 450 °C and even more suitably is in the range of from 350 to 420 °C, particularly when the lubricating base oils to be obtained are to be used in engine oils.
• the effective cutpoint of the heavy fraction is the temperature above which at least at least 85% by weight and preferably at least 90% by weight, of the hydrocarbons present in this heavy fraction has its boiling point.
• This separation or fractionation can be achieved by techniques known in the art, such as atmospheric and vacuum distillation or vacuum flashing.
• step (c) The heavy fraction obtained in step (b) is subsequently subjected to a dewaxing treatment in step (c) to arrive at the desired pour point.
• the dewaxing carried out in step (c) may in principle be carried out via any known dewaxing process.
• suitable dewaxing operations are the conventional solvent dewaxing processes, particularly those wherein methylethylketone, toluene or a mixture thereof is used as the dewaxing solvent, and the catalytic dewaxing processes. Both types of dewaxing operations are well known in the art.
• MEK methyl ethyl ketone
• Catalytic dewaxing generally involves cracking and/or isomerising linear and slightly branched paraffinic hydrocarbon molecules -which negatively influence the cold flow properties of the base oil- in the presence of hydrogen and a dewaxing catalyst under appropriate dewaxing conditions.
• Suitable dewaxing catalysts which mainly favour cracking of paraffinic hydrocarbons are those comprising ZSM-5, ferrierite and/or silicalite and optionally a hydrogenation component.
• catalysts which mainly favour isomerisation of linear or slightly branched hydrocarbons, include catalysts comprising a silicoaluminophosphate (SAPO), such as e.g. SAPO-11, SAPO-31 and SAPO-41, ZSM-23 and SSZ-32.
• SAPO silicoaluminophosphate
• Another class of suitable dewaxing catalysts for use in dewaxing step (c) are those catalysts based on a molecular sieve having pores with a diameter in the range of from 0.35 to 0.80 nm and containing covalently bound alumina moieties in its framework, which molecular sieve has been modified to reduce the mole percentage of alumina, suitably by a surface dealumination treatment.
• a particularly suitable class of dewaxing catalysts comprise a hydrogenation component supported on surface deactivated molecular sieve and optionally a low acidity refractory oxide binder material.
• the hydrogenation component may comprise at least one Group VIB metal component (e.g. one or more of tungsten, molybdenum and chromium) and/or at least one Group VIII metal component (e.g. one or more of palladium, platinum, nickel and cobalt).
• a hydrogenation component comprising platinum and/or palladium, suitably present in an amount of from 0.2 to 3.0% by weight (calculated as element and based on total weight of support, i.e. modified molecular sieve plus optional binder).
• Suitable molecular sieves include MFI-type zeolites, such as ZSM-5 and silicalite, offretite, ferrierite, ZSM-35 and zeolites of the MTT-type, such as ZSM-23 and SSZ-32. Of these, the MTT-type zeolites, ferrierite, ZSM-5 and mixtures thereof are preferred for the purpose of the present invention.
• suitable binder materials include low acidity refractory oxides such as silica, zirconia, titanium dioxide, germanium dioxide, boria and mixtures of two or more of these with silica being most preferred.
• the weight ratio of surface deactivated molecular sieve to binder may range from 10/90 to 100/0.
• the slack wax obtained in the dewaxing treatment of step (c) is suitably recycled, i.e. all or part of this slack wax is routed back to the hydroconversion step (a), most conveniently by blending it with the fresh Fisher-Tropsch wax feed. In this way the final yield of lubricating base oil can be maximised.
• the lubricating base oils obtained by the process according to the present invention can be used in a variety of oils.
• those lubricating base oils obtained from Fischer-Tropsch waxes having a T 90 between about 400 and 500 °C are very useful in electrical oils, transformer oils and refrigerator oils.
• those base oils obtained from Fischer-Tropsch waxes having a T 90 above 450 °C, suitably between 450 and 575 °C, are very useful as lubricating base oils used for the more sophisticated lubricants required in, for instance, automotive engines.
• a Fischer-Tropsch wax having the properties as listed in Table I was contacted with a fluorided NiW/alumina catalyst (5.0 %wt Ni, 23.1 %wt W, 4.6 %wt F, all based on total weight of carrier) at a temperature of 383 °C, a hydrogen partial pressure of 140 bar, a WHSV of 1 kg/l/h and a gas rate of 1,500 Nl/kg.
• the effluent was fractionated and the 390 °C+ fraction (obtained at a yield of 87.8% by weight based on total effluent) was subsequently solvent dewaxed using MEK/toluene at -20 °C.
• the resulting base oil had a VI of 165, a pour point of -15 °C, a kinematic viscosity at 100 °C (Vk100) of 4.95 mm 2 /s and a Noack volatility (as determined by CEC-L-40-T87) of 8.3% by weight.
• Total yield of lubricating base oil amounted up to 41% by weight based on Fischer-Tropsch wax feed.
• Example 2 The same Fischer-Tropsch wax as used in Example 1 was contacted with a PtPd/ASA (0.3 %wt Pt, 1 %wt Pd, ASA: silica/alumina molar ratio is 55/45) catalyst at a temperature of 332 °C, whilst the other conditions were the same as applied in Example 1.
• the effluent was fractionated and the 390 °C+ fraction (obtained at a yield of 88.3% by weight based on total effluent) was subsequently solvent dewaxed using MEK/toluene at -20 °C.
• the resulting base oil had a VI of 167, a pour point of -15 °C, a kinematic viscosity at 100 °C (Vk100) of 4.86 mm 2 /s and a Noack volatility of 7.4% by weight.
• Total yield of lubricating base oil amounted up to 39% by weight based on Fischer-Tropsch wax feed.
• Example 2 The procedure of Example 2 was repeated except that the 390 °C+ fraction obtained was catalytically dewaxed instead of solvent dewaxed.
• Catalytic dewaxing was carried out by passing said 390 °C+ fraction over a dewaxing catalyst comprising 0.7% by weight of Pt on silica-bound surface dealuminated ZSM-23 (70 %wt surface dealuminated ZSM-23, 30 %wt silica; surface dealumination carried out according to the method disclosed in U.S. Patent No.
• the resulting base oil had a VI of 151, a pour point of -27 °C, a kinematic viscosity at 100 °C (Vk100) of 4.96 mm 2 /s and a Noack volatility (as determined by CEC-L-40-T87) of 8.8% by weight.
• Total yield of lubricating base oil amounted up to 62.4% by weight based on Fischer-Tropsch wax feed.

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• 1996
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