Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
  • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
  • C07C5/373—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen with simultaneous isomerisation
  • C07C5/393—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen with simultaneous isomerisation with cyclisation to an aromatic six-membered ring, e.g. dehydrogenation of n-hexane to benzene
  • C07C5/41—Catalytic processes
  • C07C5/415—Catalytic processes with metals
  • C07C5/417—Catalytic processes with metals of the platinum group
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
  • C07C15/40—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals
• • 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
  • 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

• This invention relates to novel compositions of polyalpha-olefin (PAO) oligomers containing aromatic structures useful as lubricant basestock and lubricant additives and to their means of preparation. More particularly, the invention relates to novel lubricant compositions having high viscosity index (VI) and enhanced thermal stability prepared by dehydrocyclization of polyalpha-olefin oligomers that exhibit high VI and low pour point.
• PAO polyalpha-olefin
• PAO lubricants are often formulated with additives, or an additive package, to enhance those properties for specific applications.
• additives include oxidation inhibitors, rust inhibitors, metal passivators, antiwear agents, extreme pressure additives, pour point depressants, detergent- dispersants, viscosity index (VI) improvers, foam inhibitors and the like.
• This aspect of the lubricant arts is specifically described in Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd edition, Vol. 14, pp. 477-526. Lube additive packages are complex and costly materials.
• a significantly superior new lubricant is one in which the properties conferred on lube mixture by known additives are intrinsic to the structure of the new lubricant molecule, obviating or at least reducing the need for additives. Consequently, improvements in lubricant technology pursued by artisans in the field flow from both new additive development addressed to deficiencies in lubricant oligomers and new oligomer development for inherently better properties to displace additives.
• Increasing the aromaticity of lube mixtures is known to improve thermal stability and anti- wear properties.
• aromatic additives to PAO are often confronted with problems of solubility that limit their usefulness or require the use of costly disper- sants.
• Alkylated aromatics are known in the prior art as lubricant additives for their antiwear properties, thermal and oxidative stability as disclosed in U.S. Patent Nos. 4,211,665, 4,238,343, 4,604,491 and
• HV -PAO novel lubricant compositions
• the process comprises contacting C -C 1-alkene feedstock with reduced valence state chromium oxide catalyst on porous silica support under oligomerizing conditions in an oligomerization zone whereby high viscosity, high VI liquid hydrocarbon lubricant is produced having branch ratios less than 0.19 and pour point below -15°C.
• Lubricants produced by the process cover the full range of lubricant viscosities and exhibit a remarkably high VI and low pour point even at high viscosity.
• the molecular structure of HVI-PAO is novel and comprises the product of an essentially regular head to tail polymerization of alpha-olefin, thus providing an oligomer with large pendant alkyl groups on the recurring polymeric unit.
• Dehydrocyclization is a well known reaction in the organic chemical arts for the conversion of linear and branched alkanes to aromatic compounds, as described in Royals "Advanced Organic Chemistry", Prentice-Hall, Inc., pp. 145-147.
• the reaction is carried out typically by catalysis with dehydrogenation catalysts and proceeds through ring closure and dehydrogenation to provide an aromatic structure.
• the dehydrocyclization reaction can be characterized as a type of aromatization reaction and the terms are used interchangeably herein.
• aromatic structures can be introduced into the molecular structure of polyalpha- olefin lubricant oligomers by subjecting the polyalpha- olefin to a dehydrocyclization reaction which converts a portion of the pendant or branching alkyl groups in the recurring polymeric unit of PAO to aromatic structures.
• the starting material for dehydrocyclization is HVI-PAO
• carrying out the dehydrocyclization reaction produces a lubricant oligomer with increased aromaticity without significantly degrading the viscometric properties of the HVI-PAO, particularly the high VI of the starting material.
• PAO and HVI-PAO are produced containing aromatic structures that lend increased thermal stability, wear resistance and solubilizing characteristics to the liquid lubricant oligomers so modified.
• the improved solubilizing characteristics are particularly important for improving the solubility of aromatic additives in the modified lubricant oligomer.
• the polyalpha-olefins produced by the dehydro ⁇ cyclization process comprise novel compositions of matter containing up to five weight percent of aromatic structure attached as pendant groups to the backbone of the polyalpha-olefin structure.
• compositions have the recurring polymeric structure:
• n is 5 to 11, n is less than 500 and the ratio of n to m is between 200 and 20; wherein R contains x+1 carbon atoms comprising aryl, aralkyl or alkylaryl.
• the instant invention discloses a process for the dehydrocyclization of C 8 -C 2 polyalpha- olefin which comprises contacting the polyalpha-olefin with dehydrocyclization catalyst in a dehydrocyclization reaction zone under dehydrocylclization conditions whereby modified polyalpha-olefin is produced containing aromatic structures.
• the process is more specifically directed to the dehydrocyclization of HVI-PAO wherein the polyalpha-olefin comprises the product of the oligomerization of alpha-olefins containing 6 to 20 carbon atoms, or mixtures of such olefins.
• the oligomerization comprises contacting the olefins under oligomerization conditions, at reaction temperature of
• the oligomerization produces an oligomeric liquid lubricant composition comprising C 3 0 ⁇ c 13 o_ hY drocarbons having a branch ratio of less than 0.19, weight average molecular weight between 420 and 45,000, number average molecular weight between 420 and 18,000, molecular weight distribution, i.e. (weight average molecular weight)/ (number average molecular weight) , between 1 and 5 and pour point below -15°C.
• Figure 1 is a plot showing the relationship of hydrogen flow rate to aromaticity in the product of the present invention.
• Figure 2 is a plot showing the relationship of hydrogen flow rate to bromine number in the product of the instant invention.
• the polyalpha-olefin oligomers used as starting material in the dehydrocyclization step of the process of the instant invention are conventional commercially available PAO or HVI-PAO prepared as subsequently described.
• the conventional PAO is typically prepared by Lewis acid or Ziegler catalyst initiated oligomerization of linear 1-alkenes and can be obtained from commercial sources.
• the more commonly available commercial PAO is prepared by oligomerization of 1-decene with aluminum chloride catalyst.
• the oligomer contains a preponderance of C short chain alkyl branches of less than 8 carbon atoms.
• HVI-PAO oligomers used as starting material in the present invention are prepared by the oligomerization of
• 1-hexene HVI-PAO oligomers of the present inven- tion have been shown to have a very uniform linear C. branch and contain regular head-to-tail connections indicative of the following structure as confirmed by NMR:
• HVI-PAO oligomers have the following regular head-to-tail structure where n can be 3 to 17:
• Olefins suitable for use as starting material in the preparation of HVI-PAO include those olefins containing from 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, l-dodecene and 1-tetradecene and branched chain isomers such as 4-methyl-l-pentene. Also suitable for use are olefin-containing refinery feedstocks or effluents.
• the olefins used are preferably alpha-olefinic as for example 1-heptene to 1-hexadecene and more preferably 1-octene to 1-tetradecene, or mixtures of such olefins.
• HVI-PAO oligomers of alpha-olefins have a low branch ratio of less than 0.19 and superior lubricating properties compared to the alpha-olefin oligomers with a high branch ratio, as produced in all known commercial methods.
• HVI-PAO alpha-olefin oligomers are prepared by oligomerization reactions in which a major proportion of the double bonds of the alpha-olefins are not isomerized.
• These reactions include alpha-olefin oligomerization by supported metal oxide catalysts, such as Cr compounds on silica or other supported IUPAC Periodic Table Group VIB compounds.
• the catalyst most preferred is a lower valence Group VIB metal oxide on an inert support.
• Preferred supports include silica, alumina, titania, silica alumina, magnesia and the like.
• the branch ratios used to characterize HVI-PAO are defined as the ratios of CH groups to CH groups in the lube oil calculated from the weight fractions of methyl groups obtained by infrared methods, as published in Analytical Chemistry. Vol. 25, No. 10, p. 1466 (1953).
• the supported metal oxide catalysts are preferably prepared by impregnating metal salts in water or organic solvents onto the support. Any suitable organic solvent known to the art may be used, for example, ethanol, ethanol, or acetic acid.
• the solid catalyst precursor is then dried and calcined at 200 to 900°C by air or other oxygen-containing gas. Thereafter the catalyst is reduced by any of several various and well known reducing agents such as, for example, CO, H ,.
• the Group VIB metal may be applied to the substrate in reduced form, such as Crll compounds.
• the resultant catalyst is very active for oligomerizing olefins at a temperature range from below room temperature to 500"C at a pressure of 10 to 34,580 kPa (0.1 atmosphere to 5000 psi) .
• the oligomer ⁇ ization is carried out at a temperature between 90 and 250°C.
• Contact time of both the olefin and the catalyst can vary from one second to 24 hours.
• Very low catalyst concentrations based on feed, from 10 wt % to 0.01 wt %, are used to produce oligomers.
• the catalyst can be used in a batch type reactor or in a fixed bed, continuous flow reactor.
• Example 1 Catalyst Preparation and Activation Procedure 1.9 grams of chromium (II) acetate (Cr_(OCOCH_) 4 2H 2 0) (5.58 mmole) (commercially obtained) is dissolved in 50 ml of hot acetic acid. Then 50 grams of a silica gel of 8-12 mesh size, a surface area of 300 m 2/g, and a pore volume of 1 ml/g, also is added. Most of the solution is absorbed by the silica gel. The final mixture is mixed for half an hour on a rotavap at room temperature and dried in an open-dish at room tempera ⁇ ture.
• the dry solid (20 g) is purged with N at 250°C in a tube furnace.
• the furnace temperature is then raised to 400°C for 2 hours.
• the temperature is then set at 600°C with dry air purging for 16 hours.
• the catalyst is cooled under N to a temperature of 300°C.
• a stream of pure CO 99.99% from Matheson
• the catalyst is cooled to room temperature under N_ and ready for use.
• Example 2 A commercial chrome/silica catalyst which contains 1% Cr on a large-pore volume synthetic silica gel is used.
• the catalyst is first calcined with air at 800°C for 16 hours and reduced with CO at 300°C for 1.5 hours.
• the HVI-PAO oligomer is converted to oligomer containing aromaticity in the structure of the oligomer molecule by treating the HVI-PAO with dehydrocyclization.
• a portion of the pendant alkyl groups of the oligomer are ring-closed and dehydrogenated to form aromatic ring structures.
• up to 5 wt % aromatic structures can be incorporated into the HVI-PAO molecular structure.
• the dehydrocyclization reaction is performed on HVI-PAO oligomers produced from c 8 ⁇ c 14 alpha-olefins, with 1-decene a most preferred alpha-olefin material to produce poly-1-decene oligomer.
• C-13 NMR analysis of the products of the dehydro ⁇ cyclization process of the present invention confirm that the products comprise liquid lubricant hydrocarbon having the recurring polymeric structure
• n to m where than 500 and the ratio of n to m is between 200 and 20; wherein R contains x+i carbon atoms comprising aryl, aralkyl or alkylaryl.
• poly-1-decene dehydrocyclization product has a viscosity of at least
• the catalysts used to affect the dehydrocyclization reaction of poly-alpha-olefin oligomers in the present invention includes those typically and conventionally employed to affect dehydrocyclization of alkanes, well known to those skilled in the organic chemical arts. These include
• Group VIII metals of the CAS version of the Periodic Table of the Elements in particular platinum and palladium.
• Such catalysts are included on a solid support structure which may be taken from materials such as alumina, silica, clays, charcoal and zeolites.
• zeolites and, more particularly, large pore zeolites have been found useful.
• Such zeolites include Beta, ZSM-12, Y, which possess a Constraint Index no greater than 2 with alpha values ranging between 1 and 100.
• the zeolite(s) selected for use herein will generally possess an alpha value of at least 1, preferably at least 10 and more preferably at least 50.
• "Alpha value”, or "alpha number” is a measure of zeolite acidic functionality and is more fully described together with details of its measurement in U.S. Patent No. 4,016,218, J. Catalysis. 6 , pp. 278-287 (1966) and J. Catalysis, 61. pp. 390-396 (1980) .
• Zeolites of low acidity can be achieved by a variety of techniques including (a) synthesizing a zeolite with a high silica/alumina ration, (b) steaming, (c) steaming followed by dealu inization and (d) substituting framework aluminum with other species.
• the zeolite(s) can be exposed to steam at elevated temperatures ranging from 260° to 650°C (500° to 1200°F) and preferably from 399° to 538°C (750° to 1000°F). This treatment can be accomplished in an atmosphere of 100% steam or an atmosphere consisting of steam and a gas which is substantially inert to the zeolite.
• a similar treatment can be accomplished at lower temperatures employing elevated pressure, e.g., at from 177° to 371°C (350° to 700°F) with from 1,010 to 20,200 kPa (10 to 200 atmospheres) .
• elevated pressure e.g., at from 177° to 371°C (350° to 700°F) with from 1,010 to 20,200 kPa (10 to 200 atmospheres) .
• Specific details of several steaming procedures may be gained from the disclosures of U.S. Patent Nos. 4,325,994; 4,374,296; and 4,418,235.
• a particularly useful catalyst for the process comprises zeolite Beta bound with approximately 35 wt % alumina and containing 0.6% platinum. This catalyst was steamed to yield an effective catalyst for dehydrocyclization having an alpha value of 50.
• the process of the present invention can be run under aromatization conditions which include hydrogen feed or flow to the reactor. Hydrogen can be co-fed at a rate between 0 and 900 v/v (0 and 5000 SCF/BBL) . However, as illustrated in Figure 1, the hydrogen flow rate effects the degree of aromatization achieved. The highest aromatic content is to be found when hydrogen flow rate is zero as shown in Figure l. Hydrogen flow rate also affects the degree of residual unsaturation remaining in the product following dehydrocyclization.
• the starting material HVI-PAO typically contains at least one olefinic group per oligomer molecule.
• the degree to which this unsaturation is eliminated in the final product is influenced by hydrogen flow rate as shown in Figure 2. At high hydrogen flow rates bromine numbers less than 1 are achieved whereas at no hydrogen flow the bromine number for the poly-1-decene HVI-PAO aromatization product is greater than 6.
• the process of this invention can be conducted at temperatures between 50° and 700°C, pressures between 940 and 7000 kPa (20 and 1000 psig) and liquid hourly space velocity (LHSV) between 0.1 and 10.
• the dehydrocyclization conditions comprise a temperature between 100° and 300 ⁇ C, a pressure between 2170 and 4240 kPa (300 and 600 psig) , and LHSV between 0.4 and 1.
• the feedstock used in Examples 3-6 is HVI-PAO liquid lubricant and prepared in a fixed bed reactor according to the procedures previously described.
• the oligomerization conditions and properties of the 1-decene HVI-PAO oligomer starting material produced in a fixed bed reactor are as follows: reaction temperature 165"C, pressure 380 kPa (40 psig), WHSV 2.5, lube yield 63.6%, viscosity at 40°C 130.4 cs, viscosity at 100°C 19.7 cS, viscosity index 173.1.
• Examples 3-6 the dehydrocyclization process carried out on the feedstock was conducted in a fixed bed reactor containing an aromatization catalyst comprising zeolite Beta containing 35 wt % alumina and 0.6 wt % ° platinum.
• the catalyst is steamed to an alpha value of
• compositions comprise C -C- on hydrocarbons, said composition having a branch ratio of less than 0.19, weight average molecular weight between 420 and 60,000, number average molecular weight between 420 and 24,000, molecular weight distribution between 1 and 5, pour point below -15°C and containing between 0.4 and 4 wt % of aromatic structure.

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22225988

Family Applications (1)

Country Status (5)

Cited By (1)

Citations (8)

• 1991
  • 1991-11-22 CA CA 2123426 patent/CA2123426A1/en not_active Abandoned
  • 1991-11-22 WO PCT/US1991/008783 patent/WO1993010066A1/en not_active Application Discontinuation
  • 1991-11-22 AU AU12684/92A patent/AU668083B2/en not_active Ceased
  • 1991-11-22 EP EP9292905160A patent/EP0621860A4/en not_active Withdrawn
  • 1991-11-22 JP JP4505213A patent/JPH07501310A/ja active Pending

Patent Citations (8)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events