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
  • C10G50/00—Production of liquid hydrocarbon mixtures from lower carbon number hydrocarbons, e.g. by oligomerisation
  • C10G50/02—Production of liquid hydrocarbon mixtures from lower carbon number hydrocarbons, e.g. by oligomerisation of hydrocarbon oils for lubricating purposes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/077—Ionic Liquids

Definitions

• This invention relates to a process for the production of lubricating oils from a mixed feedstock comprising 1-olefins having 5 to 18 carbon atoms.
• the oligomers of various 1-olefins can be blended either before or after the hydrogenation or isomerization steps in order to produce the lubricating oils of the desired properties such as viscosity index and pour point.
• a feedstock containing substantially pure olefin such as eg 1-decene gives rise to a lubricant having a relatively high viscosity index but these products comprise exclusively of units which are multiples of 10 as would be expected of oligomers of decene and predominate in discrete units having 30, 40, 50, 60 and 70 carbon atoms.
• Such a blend whilst suitable for some purposes, is not an ideal synthetic lubricant since it is desirable for the molecular weight distribution of the components in a synthetic lubricant blend to simulate those of a mineral oil in their dispersity index, ie a standard deviation curve so that there is continuity and gradual blending of the components in the mixture of products.
• the molecular weight distribution of the products from discrete multiples of 10 described above do not resemble a standard deviation curve and would therefore lack the consistency of properties due to absence of a continuity and gradual blending of closely related oligomers. That is, the blend lacks consistency of properties due to the absence of a continuity and gradual blending of closely related/matched oligomers.
• the use of a relatively pure single olefin is relatively expensive.
• feedstock which would firstly meet the criteria of forming a product with the right blend of components but would also be producible from a relatively inexpensive and commercially available raw material.
• feedstock is the mixture of olefins from a Fischer Tropsch synthesis which is readily available.
• the choice of the feedstock alone is insufficient to achieve this objective since it is also necessary to identify a catalyst system and the oligomerisation conditions which would give rise to the right blend of oligomers.
• the present invention is a process for the production of lubricating oils having a viscosity index of at least 120 and a pour point of -45°C or less, said process comprising oligomerizing a feedstock comprising one or more C5 - C18 1-olefins in the presence of an oligomerization catalyst comprising an ionic liquid to form a lubricating oil.
• the 1-olefin feedstock comprises one or more olefins having 5-18 carbon atoms, preferably from 6-12 carbon atoms.
• a particularly preferred example of such a feedstock is the olefin stream formed by the Fischer Tropsch synthesis.
• Such an olefin feedstock is preferably a mixture of olefins
• FTS Fischer Tropsch synthesis
• reaction conditions of the FTS have to be controlled to obtain the desired mixture of 1-olefins.
• Gasol derived by FTS and described in "Mono-olefins Chemistry & Technology", by F Asinger, page 1089 (1968), published by Pergamon Press contains about 50% but-2-ene and is said to give poor lubricating materials on polymerization with aluminium chloride.
• any unspecified product mix of an unspecified FTS is unlikely to be suitable as feedstock for the process of the present invention.
• the FTS can be operated in such a manner that the olefin products of the synthesis contain predominantly a mixture of C7-C10 1-olefins.
• One such FTS product contains at least 2.6% w/w of 1-decene, preferably at least 7% w/w, and at least 6% w/w of 1-hexene, preferably at least 13% w/w.
• Such a product mix can be obtained by the conventional FTS processes in which the conditions of operation should be so controlled that the product has a Schulz-Flory alpha value from 0.6 - 0.9, preferably from 0.7 - 0.8.
• the Schulz-Flory alpha value is a well recognised concept and is defined eg by P J Flory in “J Am Chem Soc", 58 , 1877 (1950); and by G V Schulz in “Z Phys Chem", B43, 25 (1935).
• oligomerization catalyst used is very important. Whilst any of the conventional cationic polymerization catalysts can be used for oligomerization in general, it is essential that an ionic liquid catalyst is used if a lubricating oil of higher viscosity than that achievable by conventional catalysts is desired.
• Ionic liquids are primarily mixtures of salts which melt below room temperature.
• Such salt mixtures include (a) aluminium or gallium compound in combination with one or more of (b) imidazolium halides, pyridinium halides or phosphonium halides and the latter may be further substituted by alkyl groups.
• the ionic liquid catalyst used may comprise (a) an aluminium or gallium compound which is suitably a tri-halide, such as aluminium trichloride or gallium trichloride, or, an alkyl aluminium/gallium dihalide such as an alkyl aluminium/gallium dichloride or a dialkyl aluminium/gallium halide and is preferably ethyl aluminium/gallium dichloride.
• an aluminium or gallium compound which is suitably a tri-halide, such as aluminium trichloride or gallium trichloride, or, an alkyl aluminium/gallium dihalide such as an alkyl aluminium/gallium dichloride or a dialkyl aluminium/gallium halide and is preferably ethyl aluminium/gallium dichloride.
• the component (b) in the ionic liquid is suitably a hydrocarbyl substituted imidazolium halide, a hydrocarbyl substituted pyridinium halide, an alkylene substituted pyridinium dihalide and/or a hydrocarbyl substituted phosphonium halide.
• component (b) examples include 1-methyl-3-ethyl imidazolium chloride, 1-ethyl-3-butyl imidazolium chloride, 1-methyl-3-butyl imidazolium chloride or bromide, 1-methyl-3-propyl imidazolium chloride, ethyl pyridinium chloride or bromide, ethylene pyridinium dichloride or dibromide, butyl pyridinium chloride, benzyl pyridinium bromide and the like.
• Methods of preparation of these and other higher alkyl substituted imidazolium halides are described in our prior published EP-A-0 558 187 and WO 95/21871.
• ionic liquids which are ternary melts and comprise in addition ammonium salts such as those described in our prior published WO 95/21872 can also be used. The ionic liquids described in these prior publications are incorporated herein by reference.
• the relative ratios of the two components (a) and (b) in the ionic liquid should be such that they are capable of remaining in the liquid state under the reaction conditions.
• the relative mole ratio of aluminium/gallium compound to the component (b) in the ionic liquid is suitably in the range from 1 : 2 to 3 : 1, preferably from 1.5 : 1 to 2 : 1.
• the amount of component (a) is preferably greater than 50 mole % of the total ionic liquid.
• the ratio of the catalytic components to the 1-olefin in the feed may suitably vary in the range from 1 : 1 to 300 : 1 preferably from 10 : 1 to 200 : 1.
• concentration of the two catalytic components chosen would depend upon the specific property desired in the final lubricating oil such as eg the viscosity.
• the oligomerization is suitably carried out at ambient temperature, eg temperatures at or below 30°C, preferably around -20 to +20°C.
• the reaction pressures can be ambient or elevated.
• the oligomerization is suitably carried out in the presence of a solvent inert under the reaction conditions, preferably a paraffinic hydrocarbon eg n-hexane.
• a solvent inert under the reaction conditions, preferably a paraffinic hydrocarbon eg n-hexane.
• the ionic liquid catalyst it is preferable to add the ionic liquid catalyst to the 1-olefin feedstock and is preferably added dropwise with continuous stirring.
• the reaction mixture is allowed to stand for a duration to effect oligomerisation and the reaction mixture can thereafter be neutralised eg by bubbling ammonia therethrough, then diluted by addition of water.
• This step of neutralisation and dilution with water may be avoided since the ionic liquid forms a separate phase from the reaction mixture when allowed to stand and can be separated by simple decantation.
• the organic products can then be rendered free of the inert solvent by eg rotary evaporation.
• the above steps can be, if desired, carried out in continuous operation.
• the resultant residue is an oligomer.
• This oligomer is a lubricating oil with important and desirable properties but may contain a small proportion of olefinic groups.
• the oligomerisation products of the present invention are excellent lubricants and can be used as such or for blending with other additives in a lubricating oil.
• the products of the present process can have pour points of up to -60°C and viscosity index values above 155, eg 198. These viscosity index values are superior to those achievable by using conventional catalysts.
• the ionic liquid used was prepared by adding aliquots of aluminium chloride solid with stirring to 1-ethyl-3-methyl imidazolium chloride solid in a mole ratio of 2 : 1 respectively with cooling to 8°C. The mixture was then heated to 60°C with stirring. The resultant ionic liquid was cooled and stored in a glove box.
• the 1-olefin feedstocks used for these Examples were either single olefins or mixtures eg Raffinate II was mixed with 1-decene in various ratios as shown in the Tables below.
• the catalysts were tested in a glass autoclave cooled to -5°C.
• a heptane diluent was used to reduce reaction exotherms, typically 350 g of heptane were used.
• 450g of the olefinic feedstock was used (typically comprising 225 g each of Raffinate II and 1-decene).
• the feedstock was added to the heptane with stirring (at 1000 rpm).
• Molecular sieves (about 10 g) were added to dry the reaction mixture prior to the addition of the catalyst.
• the catalyst was neutralised by bubbling ammonia through the reaction mixture for 1-2 minutes, followed by addition of 100 ml of water. [This step was used for both the catalyst systems to compare like with like although when using an ionic liquid this step can be eliminated since ionic liquids form a separate phase from the reaction mixture and hence can be readily separated by decantation unlike the tertiary butyl chloride/ethyl aluminium dichloride catalyst which is soluble in the reaction mixture].
• ionic liquid catalysts produce a synthetic lubricant of a higher viscosity index than that achievable using a conventional tertiary butyl chloride/ethyl aluminium dichloride catalyst.
• the ionic liquid catalyst can produce a synthetic lubricant having a VI > 120 for as little as approximately 20% w/w of the 1-decene comonomer.
• the ionic liquid catalyst can produce synlube having a viscosity index above 150 cSt and a pour point of -45°C from a mixed 1-olefin feed in which each of the olefins have more than five carbon atoms.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Catalysts (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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• 1996
  • 1996-02-22 GB GBGB9603754.4A patent/GB9603754D0/en active Pending
• 1997
  • 1997-02-11 EP EP97300875A patent/EP0791643A1/en not_active Withdrawn
  • 1997-02-17 AU AU14707/97A patent/AU1470797A/en not_active Abandoned
  • 1997-02-18 ZA ZA971378A patent/ZA971378B/xx unknown
  • 1997-02-19 CA CA002197958A patent/CA2197958A1/en not_active Abandoned
  • 1997-02-20 NO NO970781A patent/NO970781L/no unknown
  • 1997-02-21 JP JP9037693A patent/JPH09235568A/ja active Pending

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