CS277629B6 - Process for producing hydrocarbon means - Google Patents

Abstract

A liq. compsn. useful as a lubricant viscosity index improver comprises the oligomerisation products of alph-olefins comprising C6-20 alpha-olefins. The compsn has a branch ratio of less than 0.19 wt. average M.W. = 15,000-200,000, number average M.W. = 5000-50,000 and M.W. distribution = 1-5. Prepn. of the compsn. useful as V.I. improver comprises contacting C6-20 alpha-olefins or mixts, under oligomeric conditions at -20-90 deg.C with a reduced valence gp. VIB metal catalyst on porous support, the catalyst having been treated at 200-900 deg.C with an oxidising gas and then with a reducing agent at a temp., and for a time, sufficient to reduce the catalyst to a lower valence state. m USE/ADVANTAGE - Umsed with lubricants to give mixts. with increased V.I. When used in blends that exhibit Newtonian flow, it increases stability to shear stress at high temp. e.g. at 150 deg.C and shear rate = 1,000,000 s-1 (claimed). C6-20 1-alkene genral oligomerisation is described in US4827064 and US4827073. (24pp Dwg.No.0/0)

Description

The present invention relates to a process for the production of novel oligomeric hydrocarbon formulations which exhibit advantageous properties when used in the form of additives for improving the viscosity index of lubricants. The present invention also relates to novel alpha-olefin oligomers and lubricant mixtures therefrom made with conventional poly-alpha-olefins or mineral oil based lubricants having a surprising degree of shear stability and high viscosity index (VI).

Synthetic poly-alpha-olefins (PAOs) have been found to be widespread and commercially successful in the field of lubricants for their convenience in mineral oil based lubricants. In the field of improving the properties of lubricants, industrial research has made efforts to develop synthetic lubricants that have resulted in PAO fluids exhibiting advantageous viscosities over a wide temperature range, i.e. improved viscosity index (VI), as well as lubricity, temperature stability, oxidation stability and point. solidification equal to or better than mineral oils. These relatively new synthetic lubricants have lower mechanical friction, increased mechanical efficiency within the full range of mechanical loads and thus have a wider range of conditions of use than mineral oils. These PAOs are prepared by polymerizing 1-alkenes usually using Lewis acids or Ziegler catalysts. Their preparation and properties are described by J. Brennan in Ind. Eng. Chem. Prod. Res. Dev. 1980, 19, pp. 2-6. Improvements in the properties of lubricants by PAO are also described in U.S. Patents J. A. Brennan 3382291, 3742082 and 3769363.

According to conventional lubricant practice, PAOs have been blended with various additives such as functional chemicals, oligomers and higher polymers and other synthetic and mineral lubricant-based oils to impart or improve the lubricating properties necessary for applications such as engine lubricants, hydraulic fluids, gear lubricants, etc. Mixtures and their additional components are described in Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition, Vol. 14, pages 477-526. A particular objective in forming mixtures is to increase the viscosity index (VI) by adding a substance that improves VI, which is usually one of the high molecular weight organic substances. These additives are commonly produced on the basis of polyisobutylenes, polymethacrylates and polyalkylstyrenes in the molecular weight range of 45,000 to 1,700,000. However, when effectively improving the viscosity index, they have proven to be inadequate in that their high molecular weight improving viscosity index is also transmitted. for the mixture and shear stability behavior of these compounds. This deficiency substantially reduces the range of suitable applications for many VI-improving agents. more commonly used VI improvers are high molecular weight acrylic materials. However, their suitability is limited by the cost as they are relatively expensive polymeric substances which can form a significant part of the final lubricant composition. For this reason, lubricant specialists are continuing to research additives to produce better lubricant compositions with a high viscosity index. However, those preferred VI improvers and VI containing lubricant compositions are less prone to shear viscosity degradation in actual applications. Preferred liquids are those that exhibit Newtonian behavior under high temperature and high shear rate conditions, i.e. viscosities are independent of shear rate. Depending on the ranges that these fluids will have in the high viscosity range under high shear stress conditions, they will have a significant advantage over conventional base lubricants. mineral oils or synthetic hydrocarbon (PAO) lubricants. This advantage can easily be demonstrated in applications such as internal combustion engines where the use of a high temperature shear resistant lubricant and the resulting high shear conditions will result in less engine wear and longer life. These fluids must also preserve or improve other important properties of satisfactory commercial lubricants such as thermal and oxidation stability.

Currently, novel lubricant formulations (referred to herein as HVI-PAO and Processed HVI-PAO) containing alpha-olefins and methods for their preparation using reduced chromium on silica as a catalyst are disclosed in US Patents 4827064 and 4827073. contact of raw material C ₆ -C ₂₀

1-alkenes with a reduced chromium oxide catalyst on a porous silica support in an oligomerization zone to form a high viscosity liquid VI high-viscosity hydrocarbon lubricant having a branching ratio of less than 0.19 and a pour point of less than -15 ° C. This process differs from the known oligomerization processes for the preparation of poly-alpha-olefins using Lewis acids as catalysts in that there is little isomerization of the olefinic bond. Their truly unique structure provides an opportunity for the preparation of quality lubricant blends.

The novel formulations have been found to be particularly useful as agents for improving the viscosity index of lubricants. These compositions containing branched hydrocarbons ^C 30 ^C i0000 'having a branch ratio less than 0.19 and viscosity at 100 ° C between 725 mir ^ .s ^"1

000 mit ^ .s ¹ . The new products include oligomerization products raw materials based on C ₆ -C ₂₀ alpha-olefins, or mixtures thereof, under oligomerization conditions at a temperature between -20 ° C to + 90 ° C when in contact with a metal of Group VIB catalyst in the reduced state on the porous support. These formulations have a viscosity at 100 ° C between

725 mm ² .s ^_1 to 15,000 mm ² .s ^_1 . The preparation of the catalyst comprises an oxidation treatment at a temperature of 200 ° C to 900 ° C in the presence of an oxidizing gas and then a treatment with a reducing agent at a temperature and for a time sufficient to reduce the catalyst to a lower valence state.

Using the above formulations in admixture with lubricants, it has been found that the lubricant compositions thus prepared exhibit increased viscosity indices. Surprisingly, it has been found that these compositions also have increased stability to high temperature shear stress at all compositions characterized by being referred to as Newtonian liquids.

The lubricant compositions of the present invention include the foregoing novel formulations and liquid lubricants selected from the group consisting of mineral oils, polyolefins and hydrogenated polyolefins, polyethers, vinyl polymers, polyfluorocarbons, polychlorofluorocarbons, polyesters, polycarbonates, polyurethanes, polyacetyles, polyamides, polyamides, , terpolymers and mixtures thereof.

The compositions of the invention may also contain other additives or additive components such as antioxidants, dispersants, extreme pressure additives, friction modifiers, corrosion inhibitors, antifoams, oxidation inhibitors, freezing point agents and other VI improvers.

In the following description, unless otherwise indicated, all references to hydrogenated olefin and lubricant properties of the oligomers or lubricants of the invention are made in accordance with established practice well known to those skilled in the art.

Accordingly, the present invention relates to a process for producing a hydrocarbon composition comprising contacting Cg- _C20 alpha-olefins, or mixtures thereof, under oligomerization conditions, with a catalyst comprising a Group VIB metal in a reduced valency state on a porous support. was treated by oxidation at 200 to 900 ° C in the presence of an oxidizing gas and then a reducing agent at a temperature and for a time sufficient to reduce the catalyst to a lower valence state so that a distinct color change and separation of the obtained composition is observed. the oligomerization reaction is carried out at a temperature between -20 and 90 ° C.

These novel oligomers of the invention, as well as the high viscosity index polyalpha-olefins (HVI-PAO) mentioned above, are unique in structure compared to conventional 1-decene polyalphaolefins (PAO) and differ primarily from the HVI-PAO oligomers in the cited reference. in that they are more viscous. It was found for the preparation of highly viscous oligomers of alpha-olefins _Cg-20 with the structure

HVI-PAO. The polymerization with the novel reduced chromium catalyst described below results in oligomers substantially free of double bond isomerization. Conventional PAO promoted by BF ₃ or AlC ₃ , forms a carbonium ion that promotes isomerization at the olefinic bond and formation of multiple isomers. The HVI-PAOs produced according to the present invention and the cited invention have a structure with a CH ₃ / CH ₂ ratio <0.19 as compared to a ratio> 0.19 for PAO.

It has been found that the process of the invention described herein for the production of novel high molecular weight or high viscosity HVI-PAO oligomers can be controlled to yield oligomers with an average molecular weight between 15,000 and 200,000 and a number average molecular weight between 5,000 and 50,000. the molecular weights are in the range of C ₃₀ to C ₁₀₀₀₀ , preferably in the range of C ₃₀ to C ₁₀₀ · Molecular weight distribution, defined as the ratio of average molecular weight to number average molecular weight, is in the range of 1.00 to 5, preferably 1, 01 to 4.

Olefins suitable as starting material for use in the present invention include alpha-olefins or 1-alkenes containing 6 to 20 carbon atoms such as 1-hexene, 1-octene, 1-decene, 1-dodecene and 1-tetradecene and branched isomers such as is 4-methyl-1-pentene. Also olefin-containing feedstocks and refinery waste are also suitable for use. However, alpha-olefins such as 1-heptene to 1-hexadecene and even more preferably 1-octene to 1-tetradecene or mixtures of such olefins are preferred for use herein.

The alpha-olefin oligomers of the invention have a low branching ratio of less than 0.19 and advantageous lubricating properties as compared to the high branching alpha-olefin oligomers produced by known methods.

This new class of alpha-olefin oligomers is prepared by oligomerization reactions in which the major part of the alpha-olefin double bonds is not isomerized. These reactions include oligomerization of alpha-olefins with supported metal oxide catalysts, such as Cr compounds on silica or other deposited compounds of the IUPAC Periodic Table group VIB. The most preferred catalysts are Group VIB Group VIB metal oxides on an inert support. Preferred carriers are silica, alumina, titanium dioxide, silica-alumina, magnesium oxide and the like. The support binds a metal oxide catalyst. Preferred are porous substances having a pore size of at least

The carrier generally has a large surface area and a large pore volume with an average pore size of 40 to 350 x 10 ⁷ mm. The high surface area is advantageous for the formation of large amounts of highly dispersed active chromium metal centers providing maximum metal utilization and resulting very high catalyst efficiency. The carrier should have an average pore size of at least. 10 ⁷ mm, preferably> 60 to 300 x ^{10 7} mm. This large pore size has no limiting effect on the diffusion of the reactant and the product from the active centers of the metal catalyst out and in, thereby further optimizing the productivity of the catalyst. For this type of catalyst, which is used in the form of a fixed bed or slurry in the reactor and is often to be recycled and recovered, a silica carrier with good mechanical properties is prevented to prevent abrasion of the catalyst particles or its decomposition during processing or reaction.

The supported metal oxide catalysts are preferably prepared by impregnating the metal salts in water or organic solvents onto the support. Any known solvent in the art, for example ethanol, methanol or acetic acid, may be used. The solid catalyst precursor is then dried and calcined at 200-900 ° C with air or other oxygen-containing gas. Thereafter, the catalyst is reduced in various ways with reducing agents such as CO, H ₂ , NH ₃ , H ₂ S, CS ₂ , CH ₃ SCHg, CH 3 SSCH 3, alkyl metal compounds such as R ₃ Al, R 3B, R ₂ Mg, R Li, R ₂ Zn, wherein R is alkyl, alkoxy, aryl and the like. Preferred are CO or H ₂ or alkyl metal compounds. Alternatively, the metals of the group can be applied

VIB onto a carrier in reduced form, such as CR ²⁺ .

The resulting catalyst is highly effective for oligomerizing olefins in the temperature range to below room temperature

500 ° C at a pressure of 10 to 34 580 kPa. In the present invention it has been found that oligomers having viscosities between 725 mm ² .s ^{-1 to} 15,000 mm ² .s ^_1 at 100 ° C can be prepared at temperatures of between -20 ° C to 90 ° C. The contact time between the catalyst and the olefin may vary from one second to 24 hours. The catalyst may be used in a batch or fixed bed reactor or a continuous flow reactor.

Generally, the carrier material can be added to a solution of metal compounds, such as acetates or nitrates, etc., then the mixture is stirred and dried at room temperature. The dry solid gel is then introduced at a sufficiently high temperature of up to 600 ° C for 16-20 hours. The catalyst is then cooled in an inert atmosphere to a temperature of 250 to 450 ° C and a stream of pure reducing agent is introduced for a time sufficient to reduce the catalyst, indicated by a color change from bright orange to pale blue. Typically, the catalyst is treated with an amount of CO equivalent to twice the stoichiometric excess needed to reduce the catalyst to a lower Cr ²⁺ valence state. Finally, the catalyst is cooled to room temperature and ready for use.

The oligomer product has a very wide range of viscosities with a high viscosity index suitable for high-performance lubrication. The oligomeric product also has an atactic molecular structure mostly of head-to-foot type with some head-to-head connections. These low branching oligomers have high viscosity indices of at least 15 to 20 units and usually 30 to 40 units higher than those of the prior art equivalent oligomers, which generally had a higher branching ratio and correspondingly lower viscosity indices. These low-branched oligomers retain better or comparable pour points.

Branching ratios are defined as the ratio of CH ₃ groups to CH ₂ groups in an oil lubricant and are calculated from the mass fractions of methyl groups obtained by the infrared spectroscopy procedure published in Analytical Chemistry, Vol. 25, No. 10, pp. 1466 (1953).

wt. methyl group fractions

Branching ratio = -1- / wt. methyl group fractions

The supported Cr oxide at various oxidation stages is known as a catalyst for the alpha-olefin polymerization of C ₃ to C ₂₀ / DE 3427319,

HLKraus and in the Journal of Catalysis 88, 424-430, 1984] using a catalyst prepared from CrO ₃ on silica. In these references it is pointed out that the polymerization proceeds at lower temperatures, usually less than 100 ° C, to form adhesive polymers and that at higher temperatures the catalyst promotes isomerization, cracking and hydrogen conversion reactions. The present invention provides medium molecular weight oligomers under reaction conditions and using catalysts that minimize side reactions such as 1-olefin isomerization, cracking and hydrogen transfer and aromatization. In order to produce novel medium molecular weight products suitable for use in conjunction with other oil improvers VI, the reaction of the invention is carried out at temperatures between -20 to 90 ° C.

The catalysts used in the present invention do not cause a significant number of side reactions.

Thus, these catalysts minimize all side reactions, but allow oligomerization of alpha-olefins to form high molecular weight, high molecular weight polymers. It is well known in the art that chromium oxides, especially with average oxidation stages +3, either pure or supported, catalyze double bond isomerization, dehydrogenation, cracking and the like. Although it is difficult to determine the exact characteristics of Cr on the support, it is believed that the catalyst of the invention is enriched in Cr (II) on the support, which is silicon dioxide, which is more efficient in catalysing alpha-olefin oligomerization at higher temperatures. isolation, cracking or hydrogenation reactions, etc. However, the crausse catalysts may be enriched in Cr (III). These catalysts for the polymerization of alpha-olefins at low reaction temperatures and provide high molecular weight polymers. However, as mentioned in these references, undesirable isomerization,. The cracking and hydrogenation reactions take place at the higher temperatures required to produce the lubricant products. The prior art in the field also teaches that chromium-based catalysts with a high proportion of Cr / III / or higher oxidation states catalyze the isomerization of butene-1 to 10 ³ times higher efficiency than polymerization of 1-butene. Catalyst quality, workmanship and reaction conditions are essential for carrying out the catalysis and composition of the product obtained and distinguish the present invention from the prior art.

Very low concentrations of catalyst relative to the feedstock are used in the present invention, with concentrations of from 10% by weight being common for the production of oligomers. up to 0.01% by weight; whereas, in the cited literature, catalyst concentrations relative to the feedstock are generally 1: 1.

The following Examples 1 and 2 illustrate a process for preparing a catalyst used to oligomerize alpha-olefins to form HVI-PAO oligomers. This process is also used to prepare the catalyst of the present invention. Example 2 illustrates a process for modifying a commercially available catalyst for preparing the catalyst of the invention.

Example 1

1.9 g chromnatého acetate, Cr ₂ / OCOCH _3/4 .2H ₂ O / 5.05 mmol / / commercially available / are dissolved in 50 ml of hot acetic acid. Then 50 g of silica gel in size from 0.833 to 0.495 mm and a surface area of 300 m ² .g ^-1 and a pore size volume of 1 mL / g. Most of the solution is absorbed onto silica gel. The resulting mixture was stirred on a rotary evaporator at room temperature for half an hour and then dried on an open dish at room temperature. First, the dry solid (20 g) is passed through nitrogen at 250 ° C in a tube furnace. The oven temperature is then raised to 400 ° C for 2 hours. The temperature of the furnace is then raised to 600 ° C and air is allowed to flow for 16 hours. After this time the catalyst is cooled under nitrogen to a temperature of about 300 ^e C. Then a stream of pure carbon

Ί

CS 277629 Β6 carbon monoxide (99.9% by Matheson) for one hour. Finally, the catalyst is cooled to room temperature under nitrogen and is ready for use.

Example 2

A commercially available chromium / silica catalyst containing 1% Cr on a large pore volume synthetic silica gel is used. The catalyst was first calcined with air at 800 ° C for 16 hours and then reduced with carbon monoxide at 300 ° C for 1.5 hours.

As mentioned above, the reduction step of preparing the HVI-PAO catalyst can be carried out with various reducing agents, although carbon monoxide is preferred. In the following Examples 3 and 4, the catalyst is prepared using carbon monoxide and hydrogen as the reducing agent, and the 1-hexene is oligomerized to form the novel composition of the invention. In both Examples 3 and 4, the oligomerization step was carried out by mixing 1.5 g of catalyst with 25 g of 1-hexene and heating under a nitrogen atmosphere at 60 ° C for 16 hours. The viscous product is isolated by filtering off the catalyst, distilling off unreacted material and low boiling fractions at 100 ° C and 13 kPa. This oligomerization can be carried out at temperatures between -20 ° C and 90 Table 1 lists the catalyst preparation conditions and the properties of the oligomer product of Examples 3 and 4.

Table 1

Example 3 4 calcinaee catalyst 800 ° C / air 800 ° C / air reduction of the catalyst CO / 350 ° C _H2 / 300 ° C oligomer yield, wt% 84 12.5 you know. Q 100 ° C, mm ² .s ^-1 1882 737 M. wt. No. χ 10 ³ 4.53 2.9 O M. wt. wt. .10 18.75 12.5 polydispersity, M. mass. mass. /M.hmotn.č. 4.14 4.2

These products from the oligomerization reactions contain certain unsaturated compounds. However, HVI-PAO with M. mass. greater than

8000, or about 500 mm ² .s ^-1 for 1-decene-based HVI-PAO has a very low degree of unsaturation in this synthesis. This unsaturation can be reduced by hydrogenation to improve the thermal and oxidative stability of the product.

The results in Table 1 show that the high viscosity of poly-1-hexene can be achieved with a chromium-activated silica supported catalyst. In this way high viscosity oligomers can be prepared from alpha-olefins ^C 7 at a temperature between -20 ° C and 90 ° C. ~ ^C 2O *

Table 2 shows the results obtained by mixing the product of Example 3 with a mineral oil containing a solvent-purified paraffinic 100 SUS base. The results show a marked improvement in viscosity and VI achieved in the mixture prepared with the novel oligomer of the invention.

Table 2

The weight percent viscosity, mm ² .s ^_1 mineral product 100 ° 40 'C IV Example 3 Oil

100 ALIGN! 0 1882.0 - - 24.9 75.1 21.78 153.18 168 10.0 90.0 8.65 52.25 142 0 100 ALIGN! 4.19 21.32 97

The following Example 5 demonstrates that a mixture of alpha-olefins can be used as a starting material for the preparation of the novel oligomers of the invention.

Example 5

Three grams of the catalyst of Example 4 was placed in a 9.5 mm fixed bed reactor and a mixture of alpha-olefins containing 17% 1-hexene, 34% 1-octene, 20% 1-decene, 14% 1-dodecene was passed through the reactor, and 15% 1-tetradecene at a rate of 10 ml per hour at 49 ° C at 2520 kPa. The effluent contained 43.6% lubricant oil and 56.4% unreacted feedstock that could be recycled to produce lubricant oil. Lubricant oil has the following viscosity characteristics:

you know. 40 ° C = 21,497 mm².s ^-1 , vis. _at 100 ° C = 1552.37 mm ² .s ^-1 ,

VI = 316 at -9 ° C.

It has been discovered that the highly viscous HVI-PAO oligomers prepared according to the present invention can be mixed with conventional synthetic polyalpha-olefins to form cross-viscous motor oils (cross-graded) such as SAE OW-20, OW-30, 5W-40 and 5W-50. By incorporating certain proportions of high viscosity HVI-PAO containing one to forty percent of the total amount of oil preparation, it provides a cross-viscosity product that exhibits a high viscosity index. Furthermore, it has been found that the above mixtures behave as Newton at high temperatures (150 ° C) and high shear rates (one million reciprocal seconds) - HTHSR ie under conditions considered in the internal combustion engine surfaces normally standardized in high shear rate tests such as is a Tannas Taperes Bearing Simulator (TBS) - ASTM D4683 - and used in engine oil standards in the European CCMC.

The Newtonian version of SAE 5W-50 High Performance Synthetic Motor Oils is produced, for example, with 20% 1046 mm ² .s ^-1 Q 100 ° C or 1073 mm ² .s ¹ Q 100 ° C HVI-PAO. These new oils have HTHSR viscosities of between 5.7 and 6.2 MPa.s compared to HTHSR viscosity values of 4.0 mPa · s commercially available high performance SAE 5W-50 synthetic engine oils. This implies that new engine oil formulations incorporating HVI-PAO can provide better engine protection than the best commercially available SAE grade grade commercial products.

The Newtonian version of the SAE OW-30 is manufactured with 11.5% 1073 mm ² .s ^-1 Q 100 ° C HVI-PAO. This oil. has a HTHSR viscosity of 3.7 mPa.s above the general lower limit of 3.5 mPa.s declared in Europe by the CCMC. Only SAE 5W-30 and SAE OW-40 mineral oil products are normally compliant with this limit. It follows that the above type of new SAE OW-30 engine oil incorporating HVI-PAO viscosity can provide equivalent engine protection to those mineral and synthetic engine oils that meet the minimum European HTHSR viscosity requirements while providing significantly better fuel economy and better efficiency at high temperatures.

Furthermore, the Newton version of the SAE OW-20 is produced with 8.4%

1073 mm ² ^ ¹ HVI-PAO. This oil has an HTHSR viscosity of 3.0 mPa.s in excess of the informal requirements of engine designers in the US, where the lower viscosity requirement is 2.6-2.9 mPa.s. This formulation incorporating high viscosity HVI-PAO would provide sufficient engine protection for US-produced cars, providing better fuel economy and better low-temperature efficiency compared to conventional, commercially available products meeting the same HTHSR requirements.

These novel engine oil formulations of the invention contain, in addition to high viscosity HVI-PAO, synthetic PAO, commercially obtained by oligomerization of 1-decene in the presence of BF ₃ or AlCl ₃ . However, other lubricants may be used outside PAO or as a substitute for PAO. These formulations also include conventional commercial additives such as esters and such additives as antioxidants, ashless dispersants and anti-wear additives. For the synthetic oils mentioned above, the additive content is 33% of the preparation. For mineral oil-based formulations, this concentration is generally lower. Best results of the mixtures according to the invention can be obtained using HVI-PAO from 100 RNN ^ .s ^"one under 20 000 mm ≤ s" ¹ at 100 C where the mixture must contain between 1-40% of the novel HVI-PAO. It is known to those skilled in the art of lubricants that the use of higher molecular weight substances, i.e. higher viscosity HVI-PAO, can be used at lower concentrations to achieve the desired VI improvement. However, consideration should be given to the possibility of some shear stability losses, which usually accompany the use of high molecular weight VI improvers such as HVI-PAO.

Table 3 lists the viscosity grades of SAE OW-20, OW-30 and 5W-50 synthetic engine oils incorporating HVI-PAO according to the invention. HTHSR dynamic viscosity results show that the results of Tannas ZBS (ASTM D4683) and Cannon Capillary (ASTM D 4624) viscosimeter are equivalent. It is also evident in all examples that the dynamic shear viscosity is the same as the dynamic shear viscosity, where the viscosities were determined from the kinematic viscosity measured at 150 ° C and the density referenced to 150 ° C by the API method at temperature measurement and therefore these products behave as Newton under HTHSR conditions.

Although the cited examples are HVI-PAO synthetic engine oils, it is to be understood that the same formulation principles apply to any lubricant where high VI is required, without shear viscosity losses such as hydraulic oils, aircraft oils, gear oils, turbine oils. , circulating oils and the like.

Although wide cross-viscosity grade lubricants such as SAE 5W-50 and OW-30 can only be made from high VI raw materials such as PAO, ester, polyglycol and XHVI mineral oils, lower cross-viscosity grade lubricants can be prepared from lower VI raw materials, such as conventional mineral oils, but which will have improved shear stability to similar formulations by conventional VI-improving techniques.

Lubricants which can be used as raw materials for the process with the VI improvers include mineral oil lubricants produced by paraffin hydrocracking, referred to herein as XHVI lubricants. These feedstocks are derived from waxes separated from oils during conventional solvent dewaxing, in particular from lubricating oil fractions containing both neutral (distillate) and residual fractions. In the process of processing waxes into XHVI lubricant feedstocks, the separated waxes are subjected to hydrocracking at high pressure, typically at 10 to 20 790 kPa above an amorphous catalyst such as alumina containing a metal component, usually based on a metal component such as nickel / tungsten. Processes of this type and the products obtained are described, for example, in British Patent Nos. 1390359, 1545828, 1324034, 1429291, 1429494, which provide a detailed description of these products and processes.

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In the case of mixtures of PAO with HVI-PAO as mentioned above, the raw material component of PAO is obtained from commercial sources such as from MOBIL Chemical Co. A commercial substance is usually prepared by oligomerizing 1-alkenes in the presence of boron trifluoride, aluminum chloride or Ziegler catalyst and is characterized by having a branching ratio greater than 0.19 and a viscosity index significantly lower than HVI-PAO. Other liquid lubricants suitable as additives for blending with HVI-PAO in the present invention include lubricating mineral oils from petroleum. Other HVI-PAO admixtures for blending include unsaturated and hydrogenated polyolefins such as polybutylene and polypropylene, liquid ethylene-propylene copolymer, and the like; vinyl polymers such as polymethyl methacrylate and polyvinyl chloride; polyethers such as polyethylene glycol, polypropylene glycol, propylene glycol, polyethylene glycol methyl ether; polyfluorinated hydrocarbons such as polytetrafluoroethylene and polyfluorinated hydrocarbons such as polychlorofluoroethylene; polyesters such as polyethylene terephthalate and polyethylene adipate; polycarbonates such as polybisphenol A carbonate; polyurethanes such as polyethylene succinoyl carbamate; silicones; polyacetals such as polyoxymethylene; polyamides such as polycaprolactam. The foregoing polymers include a copolymer thereof with known formulations having suitable lubricating properties or imparting dispersing, anti-corrosive or other properties to the compositions. In all cases, the compositions may contain additional additives.

The present invention has been described in its preferred embodiments. However, other modifications and variations are within the scope of the present invention.

Claims (5)

PATENT CLAIMS A process for the production of a hydrocarbon composition comprising contacting Cg-C ₂₀ alpha-olefins, or mixtures thereof, under oligomerization conditions, with a catalyst comprising a Group VIB metal in a reduced valence state on a porous support, the catalyst being treated by oxidation at a at a temperature of 200 to 900 ° C in the presence of an oxidizing gas and then a reducing agent at a temperature and for a time sufficient to reduce the catalyst to a lower valence state so that a distinct color change and separation of the composition is observed; between -20 ° C and 90 ° C. The process according to claim 1, wherein the catalyst comprises CO reduced CrO ₃ and the support comprises silica having a pore size of at least 40 x 10 ⁷ mm. The process according to claim 1 or 2, wherein the alpha-olefin comprises C ₁ -C ₁₄ 1-alkenes. Process according to claim 1 or 2, characterized in that the obtained hydrocarbon composition is subjected to hydrogenation. Process according to claim 1 or 2, characterized in that poly-1-decene is used as alpha-olefin.