Base Oil from NAO via Ionic Catalyst Oligomerization and Hydroisomerization

Background

To increase the fuel economy of automobile, auto manufacturers are developing higher efficiency combustion engines that operate with very low-viscosity engine oils (OW-xx engine oils including OW-8 and OW-12, which are beyond the viscosity grades that are already on the market). Demand for such low-viscosity engine oils is expected to increase rapidly in the future.

In order to make this type of specialty low-viscosity lubricant for high-efficiency engines, lubricant manufacturers need a very high quality low-viscosity base oil such as base oil from the Gas-to-Liquid process or PAO type product, in addition to the typical Group III base oils. There are only a few commercial Gas-to-Liquid plants exists and most of these plants are not designed to produce base oil, thus the supply of quality base oil from the Gas-to-Liquid plants is very limited.

Low-viscosity poly alpha olefin (PAO) is a premium synthetic base oil produced from Cio or Ci ₂ normal alpha olefins (NAO) industrially with a catalyst system composed of BF ₃ and alcohol. Due to excellent low temperature flow properties and low volatility, low-viscosity PAO is very desirable blend stock for premium lubricants for higher efficiency engines. However, this PAO is very expensive and the supply is limited. Therefore, there remains a need for a base oil composition having properties within commercially acceptable ranges for physical properties including one or more of the viscosity, Noack volatility, and low temperature cold-cranking viscosity, for use in automotive and other applications. Furthermore, there remains a

need for base oil compositions having improved properties and methods of manufacture.

A number of catalytic processes are currently in use for the oligomerization of alpha-olefins to produce lubricant base stocks.

It is also known that Lewis acids such as BF ₃ , AICI ₃ and EtAICh can be used as catalysts for cationic polymerization of alpha-olefins in conjunction with an alkyl halide (for instance tent-butyl chloride), alcohol or Brdnsted acid.

U.S. Pat. No. 7,527,944, herein incorporated by reference, discloses the use of ionic liquids as catalysts for the cationic polymerization of alpha-olefins. Ionic liquids are a class of compounds that have been developed over the last few decades. The term "ionic liquid" as used herein refers to a liquid that can be obtained by melting a salt, and which is composed entirely of ions. The term "ionic liquid" includes compounds having both high melting points and compounds having low melting points, e.g. at or below room temperature. Ionic liquids having melting points below around 30° C. are commonly referred to as "room temperature ionic liquids" and are often derived from organic salts having nitrogen-containing heterocyclic cations, such as imidazolium and pyridinium-based cations.

The ionic liquid catalysts disclosed by U.S. Pat. No. 7,572,944 comprise pyridinium or imidazolium cations together with chloroaluminate anions. The use of ionic liquids as polymerization catalysts is known to provide certain advantages over conventional catalysts. In particular, ionic liquids are generally immiscible with hydrocarbons and thus can be separated from polyalphaolefin products by phase separation and recycled. In contrast, conventional Lewis acid catalysts are generally quenched during the isolation of products. With the strong, anticipated demand growth of high-performance engines, there is a strong need for an alternative process incorporating ionic catalysts to produce low-viscosity base oil with desirable characteristics.

Summary of the Invention

An embodiment of the invention is an ionic complex catalyst and a process for olefin oligomerization of Ci - C ₂ normal alpha olefins utilizing the ionic complex catalyst in the absence of an HCI co catalyst.

An additional embodiment is an ionic liquid composition/catalyst with 2:1 anhydrous gallium chloride to 1 mole of amine chloride and a process for olefin oligomerization of CM - CM normal alpha olefins.

An additional embodiment is an ionic liquid composition/catalyst with 1.8:1 of anhydrous metal chlorides to 1 mole of amine chloride and a process for olefin oligomerization of C _M - C ₂ normal alpha olefins.

A further embodiment is a process for the production of a base oil comprising:

a. reacting a high carbon number normal alpha olefin in the presence of an ionic catalysts at a temperature of 130 °C or higher to produce oligomers;

b. hydroisomerization of the oligomer product produced in (a) under H ₂ atmosphere with a catalyst containing metal and medium pore zeolite;

c. distilling and fractionating the hydroisomerized product of (b) to produce a light fraction up to 371 °C , low-viscosity base oil in the 371 - 488 °C distillate, and high-viscosity base oil above 488 °C.

d. optionally the light fraction containing unconverted normal alpha olefins and organic chloride will be recycled to the reactor to go through the conversion step a.

Brief Description of the Drawings

Figure 1 is a block diagram for Premium Base Oil Manufacturing from C - C ₂ NAO.

Figure 2 is a GC diagram of oligomerization product showing Ci ₆ -chloride,

unreacted olefin, dimer, trimer, tetramer and higher oligomer product distribution.

Figure 3 is a plot of simulated distillation of the oligomerization product.

Figure 4 is a plot of low-viscosity selectivity of various ionic catalysts vs. conversion of Ci ₆ NAO olefin monomer.

Figure 5 is a multi- plot of branching proximity vs. free carbon index, number of methyl branches or branching index for premium low-viscosity base oil synthesis from Ci ₆ NAO, showing molecular structural modification during oligomerization and hydrofinishing steps.

Figure 6 is a multi-plot of branching proximity vs. pour point or viscosity index, showing the impact of molecular structural modification to low-viscosity base oil properties. Description of the Invention

Herein is described a process to make premium base oils using normal alpha olefins with C _M - C ₂ carbon number range (i.e., Cu - C ₂ NAO), preferentially C _M - Ci ₈ , that can be produced from a petroleum crude source via ethylene oligomerization or from bio-based sources such as natural triglycerides, fatty acids and fatty alcohols or from wax cracking. These C - C ₂ NAO will be more readily available at a lower cost than Cio and C ₂₂ NAOs. Additionally, a process is described herein with an ionic complex catalyst that requires no HCI conferring the advantages over the state of the art via: (1) Higher conversion of NAO can be achieved with ionic complex catalysts, (2) Higher selectivity for the low-viscosity base oil fraction can be achieved with ionic complex catalysts as described herein, (3) The process with an ionic complex catalyst as described herein makes less undesirable Cie-chloride by-product, (4) Lower cost for synthesis of the ionic complex catalyst.

Definition of Base Oil Properties

"Base Oil" as used herein refers to an oil used to manufacture products including dielectric fluids, hydraulic fluids, compressor fluids, engine oils, lubricating greases, and metal processing fluids.

Viscosity is the physical property that measures the fluidity of the base stock. Viscosity is a strong function of temperature. Two commonly used viscosity measurements are dynamic viscosity and kinematic viscosity. Dynamic viscosity measures the fluid's internal resistance to flow. Examples of dynamic viscosity measurements for engine oil include cold cranking simulator (CCS) viscosity and mini-rotary viscometer (MRV) viscosity. CCS is used to simulate the viscosity of oil in crankshaft bearings during cold temperature start up. Mini-Rotary Viscosity (MRV) measures the yield stress and apparent viscosity of engine oils after cooling at controlled rates and shear stress over a period exceeding 45 h to the final test temperature between -10 and -40°C. It is a critical parameter to evaluate the pumpability of an engine oil in cold weathers. The SI unit of dynamic viscosity is Pa s. The traditional unit used is centipoise (cP), which is equal to 0.001 Pa s (or 1 m Pa s). The industry is slowly moving to SI units. Kinematic viscosity is the ratio of dynamic viscosity to density. The SI unit of kinematic viscosity is mm ² /s. The other commonly used units in industry are centistokes (cSt) at 40°C (KV40) and 100°C (KV100) and Saybolt Universal Second (SUS) at 100°F and 210°F.

Conveniently, 1 mm ² /s equals 1 cSt. ASTM D5293 and D445 are the respective methods for CCS and kinematic viscosity measurements.

Viscosity Index (VI) is an empirical number used to measure the change in the base stock's kinematic viscosity as a function of temperature. The higher the VI, the less relative change is in viscosity with temperature. High VI base stocks are desired for most of the lubricant applications, especially in multigrade automotive engine oils and other automotive lubricants subject to large operating temperature variations. ASTM D2270 is a commonly accepted method to determine VI.

Pour point is the lowest temperature at which movement of the test specimen is observed. It is one of the most important properties for base stocks as most lubricants are designed to operate in the liquid phase. Low pour point is usually desirable, especially in cold weather lubrication. ASTM D97 is the standard manual method to measure pour point. It is being gradually replaced by automatic methods, such as ASTM D5950 and ASTM D6749. ASTM D5950 with 1°C testing interval is used for pour point measurement for the examples in this patent.

Volatility is a measurement of oil loss from evaporation at an elevated temperature. It has become a very important specification due to emission and operating life concerns, especially for lighter grade base stocks. Volatility is dependent on the oil's molecular composition, especially at the front end of the boiling point curve. Noack (ASTM D5800) is a commonly accepted method to measure volatility for automotive lubricants. The Noack test method itself simulates evaporative loss in high temperature service, such as an operating internal combustion engine.

Branching Index (Bl) the percentage of methyl hydrogens appearing in the chemical shift range of 0.5 to 1.05 ppm among all hydrogens appearing in the 1H NMR chemical range 0.5 to 2.1 ppm in an isoparaffinic hydrocarbon.

Branching Proximity (BP) the percentage of recurring methylene carbons which are four or more number of carbon atoms removed from an end group or branch ( -CH carbons) appearing at 13C NMR chemical shift 29.8 ppm.

Methyl Branches per Molecule: is the number that includes 2-methyl, 3-methyl, 4-methyl, 5+ methyl, adjacent methyl, and unknown methyl appearing between ¹³ C NMR chemical shift 0.5 ppm and 22.0 ppm, except end methyl carbons appearing at 13.8 ppm.

Free Carbon Index: is the average number of methylene carbons which are four or more number of carbon atoms removed from an end group or branch ( -CH carbons) per molecule.

¹³ C NMR Chemical Shift Assignments:

Ref.: Assignment of the various branch carbon resonances to specific branch positions and lengths using tabulated and calculated values (Lindeman, L. P., Journal of Qualitative Analytical Chemistry 43, 1971 1245ff; Netzel, D. A., et. al., Fuel, 60, 1981, 307ff.).

Ionic Catalyst as described herein encompasses both ionic liquid catalysts, ionic complex catalysts and Ionic liquid catalyst with HCI co-catalyst. The ionic liquid catalyst is made of anhydrous metal halides and quaternary amine salts. AlC , AIBr , GaCh or GaBr are preferred metal halides. Alkyl ammonium halides, alky imidazolium halides and alkyl pyridinium halides are preferred amine salts. Ionic complex catalyst made of anhydrous metal halides (Lewis acid) and molecules with strong electron donor atoms that will act as Lewis base with the anhydrous metal chlorides. AICI ₃ , AIBr ₃ , GaCI or GaBr are preferred metal halides. Urea, thiourea, alkyl amides and alkyl phosphines are preferred molecules.

Provided herein (l-lll) are embodiments of the process to make the disclosed low viscosity base oil composition.

I.

a. reacting a C to C normal alpha olefin monomer in the presence of an ionic catalysts at a

temperature of 130 °C or higher to produce oligomers; b. hydroisomerization of the oligomer product produced in (a) under Fl atmosphere with a catalyst containing metal and medium pore zeolite or silica-alumina;

c. distilling and fractionating the hydroisomerized product of (b) to produce a light fraction (up to 700 °F or 371 °C), low-viscosity base oil in the 700 - 910 °F (371 - 488 °C) distillate, and high-viscosity base oil above 910 °F (488 °C).

d. optionally the light fraction containing unconverted normal alpha olefins and organic

chloride in step a will be recycled to the reactor to go through the conversion step a.

An embodiment of the above process is oligomer selectivity wherein the oligomer product is predominantly dimer, with dimer selectivity equal to or greater than 40 wt to 90%, preferably greater than 50% and most preferably greater than 60%.

a. reacting a C _M to C normal alpha olefin monomer in the presence of an ionic catalysts at a temperature of 130 °C or higher to produce oligomers;

b. hydroisomerization of the oligomer product produced in (a) under H atmosphere with a catalyst containing metal and medium pore zeolite;

c. distilling and fractionating the hydroisomerized product of (b) to produce a light fraction (up to 700 °F or 371 °C), low-viscosity base oil in the 700 - 910 °F (371 - 488 °C) distillate, and high-viscosity base oil above 910 °F (488 °C) where low-viscosity base oil shows 3.5 -4.6 cSt viscosity at 100 °C with the properties of >130 VI, <15% Noack volatility, <20 °C pour and cloud points and cold crack simulator viscosity of <2500 cP at -35 °C

d. optionally the light fraction containing unconverted normal alpha olefins and organic

chloride in step a will be recycled to the reactor to go through the conversion step a.

a. reacting a C _M to C normal alpha olefin monomer in the presence of an ionic catalysts at a temperature of 130 °C or higher to produce oligomers;

b. hydroisomerization of the oligomer product produced in (a) under H atmosphere with a catalyst containing metal and medium pore zeolite;

c. distilling and fractionating the hydroisomerized product of (b) to produce a light fraction (up to 700 °F or 371 °C), low-viscosity base oil in the 700 - 910 °F (371 - 488 °C) distillate, and high-viscosity base oil above 910 °F (488 °C), where low-viscosity base oil shows 3.5 -4.6 cSt viscosity at 100 C with the Branching proximity of 17.9 - 22.2, Branching index of 20.6 - 23.0, Free carbon index of 5.8 - 7.1 and Methyl branches per molecule of 1.6-2.4 d. optionally the light fraction containing unconverted normal alpha olefins and organic

chloride in step a will be recycled to the reactor to go through the conversion step a.

Feed Stock

Feed stock is comprised of high carbon number normal alpha olefins with the carbon number ranging from 14 to 24 (C - C ₂₄ ), preferentially C - Cis from petroleum process or from bio derived alpha olefins or from wax cracking. Feed stock may contain lower carbon number normal alpha olefins in the range of C -Ci up to 40 wt% and may contain paraffins in the carbon number range of C - C up to 10 wt%. Olefin Oligomerization

In a particular embodiment of the process for Cu - C ₂ oligomerization, the chemical reaction is controlled to maximize the dimer yield and to minimize higher molecular weight oligomers (trimer, tetramers and higher oligomers). Figure 1 shows the simplified diagram of our process of invention Oligomerization may be by semi-batch or continuous mode in a suitable reactor. A particular embedment is the conversion of hexadecene to oligomer, wherein the percent conversion is in the range of 40% to 85%.

In one embodiment, the reaction mixture is distilled to remove the unreacted monomer. For example, the unreacted monomer may be separated from the oligomer product, such as via distillation, and can be recycled back into the mixture of the first and/or second feedstocks for oligomerization thereof.

Ionic Catalysts

Methods for generating ionic liquid catalysts are known in the art. U.S. Pat. No. 7,527,944, herein incorporated by reference, discloses the use of ionic liquids as catalysts for the cationic polymerization of alpha-olefins. Ionic liquids are a class of compounds that have been developed over the last few decades. The term "ionic liquid" as used herein refers to a liquid that can be obtained by melting a salt, and which is composed entirely of ions. The term "ionic liquid" includes compounds having both high melting points and compounds having low melting points, e.g. at or below room temperature. Ionic liquids having melting points below around 30° C. are commonly referred to as "room temperature ionic liquids" and are often derived from organic salts having nitrogen-containing heterocyclic cations, such as imidazolium and pyridinium-based cations.

Process conditions that maximize the conversion of the C - C ₂ NAO and the yield of dimers is set forth herein. Various ionic liquid catalysts for dimerization of C - C ₂ , can be tested using Ci ₆ NAO as the model feed.

The preferred ionic liquid composition is 2 moles of anhydrous metal chlorides to 1 mole of amine chloride. Mixing of these two ionic materials forms ionic liquid made of entirely cations and anions.

2 MCI ₃ + Amine chloride - [Amine cation] ⁺ [M ₂ CI ₇ ]

where M is a metal selected from aluminum, gallium, and indium. To improve the selectivity of the ionic liquid catalyst to low-viscosity base oil, presence of anhydrous HCI co-catalyst is required as reported in US 10,435,491, herein incorporated by reference.

The composition of the ionic liquid catalyst can be modified slightly to 1.8:1 of anhydrous metal chlorides to 1 mole of amine chloride to lower the Lewis acidity of the catalyst.

A preferred embodiment is the use of anhydrous gallium chloride containing ionic liquid catalyst demonstrating higher selectivity for low-viscosity base oil than the aluminum chloride containing catalyst.

A further embodiment of the invention is a class of ionic complex catalyst for the olefin oligomerization of Cu - C ₂ NAO demonstrating higher olefin oligomerization performance over conventional ionic liquid catalysts, specifically the ionic complex catalyst gives about 10 wt% or higher dimer selectivity than ionic liquid catalysts at a constant conversion of NAO. The class of ionic complex catalyst is a homogeneous molten liquid at ambient temperature made from 3:2 molar ratio of anhydrous, Lewis-acid metal halides and Lewis-base. Anhydrous Lewis-acid halides such as AICI ₃ , GaCI ₃ , lnCI ₃ , AIBr ₃ , All ₃ , GaBr ₃ , Gal ₃ , lnBr ₃ and lnl ₃ can be used to make the ionic complex catalyst. Suitable solid Lewis-bases include molecules containing atoms with electron pair such as oxygen, phosphorus, sulfur, nitrogen. Examples of Lewis-bases include lutidine, collidine, alkylpyridines, trioctylphosphine, alkylphosphines, trioctylphosphine oxide, alkylphosphine oxides, ureas (e.g., N,N'-dimethyl urea, N,N'-diethyl urea), thioureas (e.g., thiourea, N-methylthiourea, N,N'- dimethylthiourea, N-ethylthiourea, N,N'-diethylthiourea), amides (e.g., acetamide, propionamide, benzamide), dialkyacetamides, alkylamides, octanenitrile, and alkylnitriles. When these two solids ingredients (strong Lewis-acid and Lewis-base) in powder form are mixed in 3:2 molar ratio, their strong interaction induces deep eutectic behavior to the combined solid powders, and the mixture becomes liquid at the ambient temperature.

Without being bound by any theory, it is believed addition of a strong Lewis donor ligand to a Group 13 metal halide results in disproportionation of the metal species into cationic and anionic ionic complexes which exists in equilibrium with neutral complexes, such as described in the following equation:

where M is a metal selected from aluminum, gallium and indium; X is a halides selected from chloride, bromide, and iodide; and L represents a Lewis basic donor ligand. The eutectic behavior (becoming liquid) may be coming from ionic species formation.

Hydroisomerization

As a finishing step, the oligomer product is hydrogenated with a hydrogenation catalyst in the presence of hydrogen at an elevated pressure to make fully saturated base oil. Heterogeneous, hydrogenation catalyst containing nickel is commonly used for PAO hydrogenation. Precious metal, such as Pt, Pd, or Ru, supported catalyst can also be used for hydrogenation of oligomers.

Hydroisomerization catalysts useful in the present invention usually comprises a shape-selective molecular sieve, a metal or metal mixture that is catalytically active for hydrogenation, and a refractory oxide support. The presence of a hydrogenation component leads to improvement in product stability. Typical catalytically active hydrogenation metals include chromium, molybdenum, nickel, vanadium, cobalt, tungsten, zinc, platinum, and palladium. Platinum and palladium are especially preferred, with platinum mostly preferred. If platinum and/or palladium is used, the metal content is typically in the range of 0.1 to 5 weight percent of the total catalyst, usually from 0.1 to 2 weight percent, and not to exceed 10 weight percent. Hydroisomerization catalysts are discussed, for example, in U.S. Patent Nos. 7,390,763 and 9,616,419, as well as U.S. Patent Application Publications 2011/0192766 and 2017/0183583.

Platinum and palladium and ruthenium may be the preferred metals for hydroisomerization. Other Group VI II transition metals such as Ni, Co, Fe, W, Re, Os or Ir may be used for the process. Zeolite containing one-dimensional or two-dimensional, 10-membered ring pore structure, such as those having M FI, M EL, M FS, M RE, MTT, SFF, STI, TON, OSI, or NES framework type may be used. Suitable zeolites include ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32, SSZ-35, SSZ-91, SSZ-95, SSZ-109, NU-87, ALPO-31, SAPO-11. Amorphous materials with acidic sites in combination with metal may be used for hydroisomerization. Suitable amorphous materials include amorphous silica- alumina, silica-alumina-titania, zirconia-alumina and zirconia-ceria-alumina. The conditions for hydroisomerization are tailored to achieve an isomerized hydrocarbon mixture with specific branching properties, as described above, and thus will depend on the characteristics of feed used. The reaction temperature is generally between about 200°C and 400°C, preferably between 260°C to 370°C, most preferably between 288°C to 345°C, at a liquid hourly space velocity (LHSV) generally between about 0.2 hr ¹ and about 5 hr ¹ , preferably between about 0.5 hr ¹ and about 3 hr ¹ . The pressure is typically from about 15 psig to about 2500 psig, preferably from about 50 psig to about 2000 psig, more preferably from about 100 psig to about 1500 psig, most preferably 100 to 800 psig. Low pressure provides enhanced isomerization selectivity, which results in more isomerization and less cracking of the feed, thus leading to an increased yield of hydrocarbon mixture in the base stock boiling range. Hydrogen is present in the reaction zone during the hydroisomerization process, typically in a hydrogen to feed ratio from about 0.1 to 10 MSCF/bbl (thousand standard cubic feet per barrel), preferably from about 0.3 to about 5 MSCF/bbl.

Hydrogen may be separated from the product and recycled to the reaction zone.

The hydroisomerized product was distilled to produce three fractions, 700°F (371°C) light fraction, low-viscosity base oil cut (700 - 910°F or 371 - 488°C) and high-viscosity base oil cut (910°F ⁺ or 488°C ⁺ ). The low-viscosity cut in the 700 - 910°F (371 - 488°C) boiling range is mainly made of dimer product and high-viscosity cut in 910°F ⁺ (488°C ⁺ ) boiling range contains trimer, tetramers and higher oligomers.

Product Properties for Premium Base Oil

The low-viscosity fraction contains predominately the dimers and a small amount of trimers. The high-viscosity fraction contains mostly trimer and tetramers. The typical GC diagram and simdist plot of desirable oligomer product distribution are shown in Figures 2 and 3.

To meet the performance requirement as well as meeting the environmental requirements, the desirable base oil properties are low-viscosity, high viscosity index (VI), low pour and cloud points, low Noack volatility, and low temperature cold crank simulator (CCS) viscosity.

Premium base oil properties described herein are as follows (Table 1):

Table 1

Target Properties for Premium Base Oil Synthesis from NAO

The oligomer products made from high carbon number, normal alpha olefins (C _M - C ) have very high viscosity index (VI) of over 150, well exceeding the target VI of above 130. However, the dimer products have major drawbacks for low temperature performances. The oligomer products are waxy and show poor low temperature properties of pour and cloud points. Base oil properties are further improved by substituting the hydrogenation finishing step with a hydroisomerization finishing process using a metal containing, medium pour zeolite catalyst.

The oligomerized product was hydroisomerized under the Fh atmosphere with a catalyst containing precious metal and medium pore zeolite to saturate the double bonds in the olefin oligomers and isomerize the carbon backbone structure at the same time. The resulting products met all target properties of the premium low-vis base oil. No additional, subsequent hydrogenation step is required.

The hydroisomerization process also generates several percentage of offgas and light products (gasoline and diesel boiling range hydrocarbons), causing some loss of base oil yield. The yield loss could be as high as 8-10 vol%. Lowering the yield loss to a minimum is highly desirable. We achieved by operating the oligomerization at high temperature, 130 °C or above, to induce isomerization of hydrocarbon backbone in the oligomer product and then followed by mild hydroisomerization. By combining this optimized process, we achieved over 95% of premium base oil yield from the starting NAO.

A low-viscosity base oil composition in accordance with the present invention will generally exhibit the following characteristics:

Kinematic Viscosity at 100° of 3.5 - 4.6 cSt

Branching proximity of 17.9 - 22.2

Branching index of 20.6 - 23.0

Free carbon index of 5.8 - 7.1

Methyl branches per molecule of 1.6-2.4

Viscosity index of 130 - 142

Pour point of -20 to -60 °C

Lubricant Formulations with Base Oil

The base oil disclosed herein can be used as lubricant base stocks to formulate final lubricant products comprising additives. In certain variations, a base stock prepared according to the methods described herein is blended with one or more additional base stocks, e.g., one or more commercially available PAOs, a Gas to Liquid (GTL) base stock, one or more mineral base stocks, a vegetable oil base stock, an algae-derived base stock, a second base stock as described herein, or any other type of renewable base stock. Any effective amount of additional base stock may be added to reach a blended base oil having desired properties. For example, blended base oils can comprise a ratio of a first base stock as described herein to a second base stock (e.g., a commercially available base oil PAO, a GTL base stock, one or more mineral base stocks, a vegetable oil base stock, an algae derived base stock, a second base stock as described herein) that is about is from about 1-99%, from about 1-80%, from about 1- 70%, from about 1-60%, from about 1-50%, from about 1-40%, from about 1-30%, from about 1-20%, or from about 1-10%, based on the total weight of the composition may be made.

Also disclosed herein are lubricant compositions comprising a hydrocarbon mixture described herein. In some variations, the lubricant compositions comprise a base oil comprising at least a portion of a hydrocarbon mixture produced by any of the methods described herein, and one or more additives selected from the group of antioxidants, viscosity modifiers, pour point depressants, foam inhibitors, detergents, dispersants, dyes, markers, rust inhibitors or other corrosion inhibitors, emulsifiers, de-emulsifiers, flame retardants, antiwear agents, friction modifiers, thermal stability improvers, multifunctional additives (e.g., an additive that functions as both an antioxidant and a dispersant) or any combination thereof. Lubricant compositions may comprise hydrocarbon mixtures described herein and any lubricant additive, combination of lubricant additives, or available additive package.

Any of the compositions described herein that are used as a base stock may be present at greater than about 1% based on the total weight of a finished lubricant composition. In certain embodiments, the amount of the base stock in the formulation is greater than about 2, 5, 15 or 20 wt% based on the total weight of the formulation. In some embodiments, the amount of the base oil in the composition is from about 1-99%, from about 1-80%, from about 1-70%, from about 1-60%, from about 1-50%, from about 1-40%, from about 1-30%, from about 1-20%, or from about 1-10% based on the total weight of the composition. In certain embodiments, the amount of base stock in formulations provided herein is about 1%, 5%, 7%, 10%, 13%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 99% based on total weight of the formulation.

As is known in the art, types and amounts of lubricant additives are selected in combination with a base oil so that the finished lubricant composition meets certain industry standards or specifications for specific applications. In general, the concentration of each of the additives in the composition, when used, may range from about 0.001 wt.% to about 20 wt.%, from about 0.01 wt.% to about 10 wt.%, from about 0.1 wt.% to about 5 wt.% or from about 0.1 wt.% to about 2.5 wt.%, based on the total weight of the composition. Further, the total amount of the additives in the composition may range from about 0.001 wt.% to about 50 wt.%, from about 0.01 wt% to about 40 wt%, from about 0.01 wt% to about 30 wt%, from about 0.01 wt.% to about 20 wt.%), from about 0.1 wt.% to about 10 wt.%, or from about 0.1 wt.% to about 5 wt.%, based on the total weight of the composition.

In some variations, the base oils described herein are formulated in lubricant compositions for use as two cycle engine oils, as transmission oils, as hydraulic fluids, as compressor oils, as turbine oils and greases, as automotive engine oils, as gear oils, as marine lubricants, and as process oils. Process oils applications include but are not limited to: rolling mill oils, coning oils, plasticizers, spindle oils, polymeric processing, release agents, coatings, adhesives, sealants, polish and wax blends, drawing oils, and stamping oils, rubber compounding, pharmaceutical process aids, personal care products, and inks.

In yet other variations, the base oils described herein are formulated as industrial oil or grease formulations comprising at least one additive selected from anti-oxidants, anti-wear agents, extreme pressure agents, defoamants, detergent/dispersant, rust and corrosion inhibitors, thickeners, tackifiers, and demulsifiers. It is also contemplated that the base stocks of the invention may be formulated as dielectric heat transfer fluids composed of relatively pure blends of compounds selected from aromatic hydrocarbons, polyalphaolefins, polyol esters, and natural vegetable oils, along with additives to improve pour point, increase stability and reduce oxidation rate.

The present invention will be further illustrated by the following examples, which are not intended to be limiting.

Example 1: Ionic Liquid Catalysts with Anhydrous Aluminum Chloride

Example 1-1: N-butylpyridinium chloroaluminate (C5H5NC4H9AI2CI7, abbreviated as [BuPyHAhCb]) N-butylpyridinium chloroaluminate was synthesized in a glove box under N ₂ atmosphere by slowly mixing 2:1 mole ratio of anhydrous AICI ₃ powers and dried N-butylpyridinium chloride powers together. Slight heat was applied to ~50 °C while stirring, and the mixture became liquid. Then a small fraction of each solid at a time was added alternately to the beaker to continue to make the molten liquid until all ingredients are added and dissolved well. Continued the stirring of the liquid overnight and then filtered it with a fine frit to remove any residual solid. The composition of this ionic liquid catalyst is shown in Table 2.

Example 1-2: l-Butyl-3-Methyllmidazolium chloroaluminate (abbreviated as [BMIM][AI ₂ CI ₇ ])

This ionic liquid was synthesized using the procedure of Example 1-1, except using l-butyl-3- methylimidazolium chloride is used in the synthesis.

Example 1-3: l-Ethyl-3-Methyllmidazolium chloroaluminate (abbreviated as [EMIM][AI ₂ CI ₇ ])

This ionic liquid was synthesized using the procedure of Example 1-1, except using l-ethyl-3- methylimidazolium chloride is used in the synthesis.

Example 1-4: N-Butyl-3-MethylPyridinium chloroaluminate (C H N(C H )(CH )AI ₂ CI ₇ , abbreviated as [BMPy][AI ₂ CI ₇ ])

This ionic liquid was synthesized using the procedure of Example 1-1, except using N-butyl-3- methylpyridinium chloride is used in the synthesis.

Example 1-5: N-butylpyridinium chloroaluminate (abbreviated as [BuPy][1.8 AI ₂ CI ₇ ])

This ionic liquid was synthesized using the procedure of Example 1-1 and the same starting material. However, the molar ratio of the anhydrous AICI ₃ and N-butylpyridinium chloride is 1.8:1. This lowers the acidity of the catalyst slightly and improves the dimer selectivity.

Table 2

Composition of Ionic Liquid Catalyst

Example 2: Ionic Liquid Catalyst with Anhydrous Gallium Chloride, N-butylpyridinium chlorogallate (C ₅ H ₅ NC H Ga Cl , abbreviated as [BuPy][Ga ₂ CI ₇ ])

N-butylpyridinium chlorogallate was synthesized in a glove box under N ₂ atmosphere by slowly mixing 2:1 mole ratio of anhydrous GaCI ₃ powers and dried N-butylpyridinium chloride powers together. Slight heat was applied to ~50 °C while stirring, and the mixture became liquid. Then a small fraction of each solid at a time was added alternately to the beaker to continue to make the molten liquid until all ingredients are added and dissolved well. Continued the stirring of the liquid overnight and then filtered it with a fine frit to remove any residual solid. Example 3: Olefin Oligomerization Performance of Various Ionic Liquid Catalysts

This example shows performance of various ionic liquid catalysts. The catalysts were compared for the performance for the NAO oligomerization step and the properties of the finished, hydrogenated base oil fractions.

n-Hexadecene normal alpha olefin (Ci ₆ ⁼ NAO) was oligomerized using an ionic liquid catalyst from Examples 1 and 2. Olefin oligomerization process using the ionic liquid was very effective. Only 0.5 vol% of ionic liquid catalyst was used for a batch run at 100 °C. A small amount of HCI co-catalyst was added.

Each oligomer product was hydrogenated with a Pt, Pd/alumina catalyst. Then the final, whole liquid product was distilled to produce three fractions, 700°F light fraction, low-viscosity base oil cut (700 - 910°F) and high-viscosity base oil cut (910°F+), and the base oil properties were measured. The performance summary and final base oil properties are summarized in Table 3.

Table 3

Performance of Various Ionic Liquid Catalysts for Oligomerization of n-Ci ₆ ⁼ NAO and

Physical Properties of Hydrogenated Base Oil Products

The results above show that ionic liquid catalyst is very active in oligomerizing the normal alpha olefins. Only 0.5 vol% of catalyst was used for the reactions and good conversions in the range of 25.5 to 59.1% were achieved. The resulting base oil products have very high viscosity index, ranging from 153 to 164. However, the base oil products have poor low temperature properties and the pour and cloud points are far from the targets. The best cold flow properties were obtained with [EMIM][AI ₂ CI ₇ ]. Among the AICI ₃ containing ionic liquid catalysts, [EM I M] [AI ₂ CI ₇ ] gave the highest conversion of alpha olefin during the oligomerization step, and produced low-viscosity base oil with much better pour point (-16 °C) and cloud point (-14 °C), while the viscosity index is slightly lower to 153. This suggests that the [EM I M] [AI ₂ CI ₇ ] catalyst induced some isomerization of carbon backbone during the oligomerization and made the oligomer product more branched and less waxy. This

isomerization/ branching lowered the viscosity index and improve the cold properties, i.e.

lowered the pour and cloud points.

Gallium containing ionic liquid catalyst, [BuPy][Ga ₂ CI ₇ ], is more selective for low-viscosity base oil. AICI containing ionic liquid catalyst (Example 3.3) and [BuPy][Ga ₂ CI ₇ ] (Example 3.5) show very similar olefin conversion of ~47%. The [BuPy][Ga ₂ CI ₇ ] catalyst showed 63.6% low- viscosity oil selectivity while [EMIM][AI ₂ CI ₇ ] showed 38.1%.

The low-viscosity oil selectivity of each catalyst was plotted as a function of NAO conversion in Figure 4. This figure compares the potential of each class of ionic catalysts for selective production of low-viscosity oil. All aluminum chloride containing ionic liquid catalysts achieved only about 40 wt.% selectivity to the low-viscosity oil fraction while gallium chloride containing ionic liquid catalyst showed about 60+ wt.% selectivity, about 20+ wt.% improvement.

Example 4-1: Improvement of Olefin Oligomerization Process with Ionic Liquid Catalysts

This example shows oligomerization process improvement to incorporate more isomerization during the oligomerization process. To our surprise, we discovered new olefin oligomerization conditions that provides (1) high conversion of olefin, (2) high selectivity for dimer product, and (3) much improved product properties of the finished base oil. The effects of the performance features are summarized in Table 4.

Table 4

Process Improvement for Ionic Liquid Catalyzed Oligomerization of n-Ci ₆ ⁼ NAO and

Physical Properties of Hydrogenated Base Oil Products

*: The product property values for Example 4-1 in Table 3 are from the batch

oligomerization run sample of Example 3-1.

n-Hexadecene normal alpha olefin (Ci ₆ ⁼ NAO) was oligomerized using [BuPy][1.8AI ₂ CI ₇ ] and from Example 1-5. Oligomerization was run in a continuous unit with 0.2 vol% of ionic liquid catalyst. A small amount of HCI co-catalyst was added. The oligomerization temperature performed was as low as 80 °C and then raised to 130 and 180 °C.

As the temperature of the oligomerization is increased from 80 °C to 130 °C, the olefin conversion dropped from 53 to 41%. This conversion drop at the higher temperature was observed in the earlier study using Cio NAO oligomerization (US 10,435,491). Based on this, we used to limit the upper temperature range to 130 °C for Cio NAO oligomerization.

When we raised the oligomerization temperature to 180 °C, to our surprises, the olefin conversion was increased to a value even higher than the 80 °C olefin oligomerization (53% at 80 °C, 41% at 130 °C, and then 56% at 180 °C). The dimer selectively was also significantly increased at higher temperature. The dimer selectivity was 57% at 180 °C and only 15% at 80 °C.

The oligomer product (300 g) was hydrogenated with 30 g of Pt, Pd/alumina catalyst in a batch mode at 250 °C, 800 psig for 6 hours. Then, the final, whole liquid product was distilled to produce three fractions, 700°F (371°C) light fraction, low-viscosity base oil cut (700 - 910°F or 371 - 488°C) and high-viscosity base oil cut (910°F ⁺ or 488°C ⁺ ), and the base oil properties were measured.

The results in Table 4 indicate that oligomerization at a high temperature of 180 °C improves the low temperature properties of the finished base oil significantly while decreasing the viscosity index within the desirable range. The results show that oligomerization temperature of 130 °C is not high enough to improve the low temperature properties of the base oil. With 180 °C oligomerization, the finished product show -20 °C pour point and -5 °C cloud point. These improvements allow the finished base oil closer to meet the target properties of the premium base oil shown in Table 1, but not quite all the way meeting the targets.

Example 4-2: Structural Analysis of Base Oil from Improved Olefin Oligomerization Process with Ionic Liquid Catalysts

Composition of the hydrogenated, low-viscosity base oil products from Examples 4-2 and 4-3 were analyzed using nuclear magnetic resonance spectroscopy (NMR) to determine the extent of isomerization of carbon backbone and branching (migration of methyl group) during the oligomerization process. The NMR spectra were acquired using Bruker 500 spectrometer. Each sample was mixed 1:1 (wt:wt) with CDCI ₃ . The *H NMR and ¹³ C NMR spectra were and analyzed to obtain the structural parameters.

Table 5

Relationship Between Oligomerization Process Variables to Average Molecular Structure of

Low-Viscosity Base Oil (Hydrogenated n-Ci ₆ ⁼ NAO Oligomer)

Branching Proximity: % E-CH ₂ carbons among total carbons

Branching Index: % methyl hydrogens among total aliphatic hydrogens

Methyl Branching per molecule: number of internal methyl groups in the molecule, not include the primary carbon methyl groups in the end of the molecule

Free Carbon Index: total number of E-CH ₂ carbons per molecule

The results in Table 5 shows that oligomerization at 180 °C, increased the branching index, i.e. more methyl branching in the molecule was created. This lowered the viscosity index and lowered the pour and cloud points.

Example 5: Synthesis of various Ionic Complex Catalyst

Example 5-1: Synthesis of Ionic Complex Catalyst - TOPO-AICI ₃

An ionic complex made of 3:2 molar ratio of anhydrous aluminum chloride and trioctylphosphine oxide was prepared by using 200.3 g of anhydrous AICI ₃ and 386.7 g of trioctylphosphine oxide ((C ₈ H _I7 C) ₃ PO). As-received trioctylphosphine oxide was dried in a vacuum oven at 40 °C overnight. Anhydrous aluminum chloride was used as-received. The synthesis was done in a glove box. About 1/20 of the amount of aluminum chloride and trioctylphosphine oxide powders were mixed in a beaker with a magnetic stirrer. Slight heat was applied to ~50 °C while stirring, and the mixture became liquid. Then about 1/20 fraction of each solid at a time was added alternately to the beaker to continue to make the molten liquid until all ingredients are added and dissolved well. Continued the stirring of the liquid overnight and then filtered it with a fine frit to remove any residual solid. The composition of this ionic complex catalyst is shown in Table 6.

Example 5-2: Synthesis of Ionic Complex Catalyst - Urea-AICI ₃

An ionic complex made of 3:2 molar ratio of anhydrous aluminum chloride and urea was prepared by using 480.6 g of anhydrous AICI ₃ and 144.1 g of urea (H ₂ NCONH ₂ ). As-received urea was dried in a vacuum oven at 80 °C overnight. Anhydrous aluminum chloride was used as-received. The synthesis was done in a glove box. About 1/20 of the amount of aluminum chloride and urea powders were mixed in a beaker with a magnetic stirrer. Slight heat was applied to ~50 °C while stirring, and the mixture became liquid. Then about 1/20 fraction of each solid at a time was added alternately to the beaker to continue to make the molten liquid until all ingredients are added and dissolved well. Continued the stirring of the liquid overnight and then filtered it with a fine frit to remove any residual solid. The composition of this ionic complex catalyst is shown in Table 6.

Example 5-3: Synthesis of Ionic Coordination Complex - Acetamide-AICI ₃

An ionic complex made of 3:2 molar ratio of anhydrous aluminum chloride and acetamide was prepared by using 413.9 g of anhydrous AICI ₃ and 122.1 g of acetamide (CH ₃ CONH ₂ ). As-received acetamide was dried in a vacuum oven at 70 °C overnight. Anhydrous aluminum chloride was used as-received. The synthesis was done in a glove box. About 1/20 of the amount of aluminum chloride and acetamide powders were mixed in a beaker with a magnetic stirrer. Slight heat was applied to ~50 °C while stirring, and the mixture became liquid. Then about 1/20 fraction of each solid at a time was added alternately to the beaker to continue to make the molten liquid until all ingredients are added and dissolved well. Continued the stirring of the liquid overnight and then filtered it with a fine frit to remove any residual solid. The composition of this ionic complex catalyst is shown in Table 6.

Example 5-4: Synthesis of Ionic Coordination Complex - TOP-AICI ₃

An ionic complex made of 3:2 molar ratio of anhydrous aluminum chloride and trioctylphosphine was prepared by using 160.2 g of anhydrous AICI ₃ and 296.5 g of trioctylphosphine ((CgHi ₇ C) ₃ P). As- received samples were used as-received. The synthesis was done in a glove box. About 1/20 of the amount of aluminum chloride powders and trioctylphosphine liquid were mixed in a beaker with a magnetic stirrer. Slight heat was applied to ~50 °C while stirring, and the mixture became liquid. Then about 1/20 fraction of each component at a time was added alternately to the beaker to continue to make the molten liquid until all ingredients are added and dissolved well. Continued the stirring of the liquid overnight and then filtered it with a fine frit to remove any residual solid. The composition of this ionic complex catalyst is shown in Table 6.

Table 6

Composition of Ionic Coordination Complex Samples

Example 6: Olefin Oligomerization of Ci ₆ NAO with Ionic Coordination Complex of AICI ₃ and Lewis Base

This example reports performance of the ionic coordination complex catalysts described in Example 5, and compare the results with those of ionic liquid catalyst (Example 1.1). 1-hexadecene was oligomerized in the presence of ionic coordination complex catalysts of Example 5. A three-neck, 2 L round bottom flask equipped with a magnetic stir bar, a dropping funnel and a reflex condenser was prepared. About 500 cc of 1-hexadecene was loaded to the flask and a very small purge of dry nitrogen gas was applied while heating the liquid to 150 °C. Once the 1- hexadecene in the round bottom flask reached thermal equilibrium, 0.25 or 0.5 vol% of the ionic coordination complex from Example 5 was added dropwise for 10 minutes interval using a dropping funnel. After the addition, the oligomerization reaction continued for 30 more minutes to produce the reaction mixture.

The hydrocarbon product was recovered and analyzed with GC simulated distillation method to calculate the conversion of Ci ₆ ⁼ NAO, and the selectivities for Ci ₆ -organic chloride, low-viscosity base oil and high-viscosity base oil. The results are summarized in Table 7.

The oligomer product with the TOPO- AICI ₃ catalyst was hydrogenated to produce the finished base oil cuts and the properties are reported in Table 1.

Performance of Various Ionic Complex Catalyst for Oligomerization of n-Ci ₆ NAO

Comparison of Ionic Complex Catalyst vs. Ionic Liquid Catalysts

To our surprise, we found ionic coordination complex catalyst are more active than the ionic liquid catalysts. At 150 °C reaction temperature, the ionic complex catalysts achieved 1-hexadecene conversion of 56.9 to 81.2% while the [BuPy][AICI ₃ ] ionic liquid catalyst required 180 °C reaction temperature to achieved 56.1 % conversion (Examples 6-1 through 6-3 vs. Example 3-4).

We also found ionic coordination complex catalyst are more selective for low-viscosity cut than the ionic liquid catalyst. Example 6-1 vs. 3-4 have similar 1-hexadecene conversion. The ionic complex catalyst (Example 6.1) shows 68.2% dimer selectivity and which is superior than that of ionic liquid catalyst (56.8% dimer selectivity in Example 3.4).

Acetaminde-AICh catalyst achieved very good conversion of 69.2% with only 0.25 vol% catalyst loading. This catalyst showed very good dimer selectivity of 64 wt%.

Figure 4 also contains the low-viscosity oil selectivity data of ionic complex catalysts as a function of NAO conversion. This figure compares the potential of each class of ionic catalysts for production of low-viscosity oil. The figure shows that the low-viscosity oil selectivity of as high as 80 wt.% could be achieved with these ionic complex catalyst. This is a significant improvements over the bench mark ionic liquid catalyst containing aluminum chloride (about 40%), or over the gallium chloride containing ionic liquid catalyst (about 10%).

Another surprise was that we do not need to add anhydrous HCI to the catalyst to obtain good selectivity. Without the HCI addition, the formation of Ci ₆ -chloride is less with the ionic complex catalysts. This will make the product finishing easier.

Example 7 - Improvement of Finished Oil Properties with Hydroisomerization Finishing Step

This example shows the use of hydroisomerization finishing step to improve the product properties of the premium base oil.

n-Hexadecene normal alpha olefin (Ci ₆ ⁼ NAO) was oligomerized using an ionic liquid catalyst from Example 1-1. Only 0.5 vol% of ionic liquid catalyst was used for a batch run at 100 °C. A small amount of HCI co-catalyst was added.

The oligomer product was split in three ways. One batch of oligomer product was hydrogenated with a Pt, Pd/alumina catalyst. Two other batches of oligomer products were hydroisomerized using a noble metal and medium pore zeolite to saturate the double bonds and isomerize the carbon backbone structure at the same time. Then the final, whole liquid products were distilled to produce three fractions, 700°F- (371°C) light fraction, low-viscosity base oil cut (700 - 910°F or 371 - 488°C) and high-viscosity base oil cut (910°F ⁺ or 488°C ⁺ ). The base oil cuts have the physical properties shown in Table 8.

Table 8

Improvement of Base Oil Properties with Hydroisomerization Finishing Step

Physical Properties Base Oil Made from Cie ⁼ NAO Oligomerization and Finishing

Comparison of Hydrogenation vs. Hydroisomerization Finishing Step

Example 7-1 shows properties of base oil made by olefin oligomerization with an ionic liquid catalyst followed by hydrogenation using a Pt,Pd/AI203 catalyst. The product (low-viscosity base oil and high-viscosity base oil fractions) has an excellent viscosity index of 152 and 156 respectively.

However, the base oil is waxy and has poor cold flow properties in that the low-vis base oil fraction shows -4 °C of pour point and 6 °C of cloud point, and the heavy oil fraction shows -1 °C of pour point and 0 °C of cloud point. The low-vis base oil fraction becomes too waxy at lower temperatures and shows very poor CCS viscosity at -30 °C. Due to the poor cold flow properties, this product is not adequate as a premium low-viscosity base oil.

Example 7-2 was a base oil produced by the exact same oligomerization process as in Example 7-1 except the hydroisomerization finishing step. It was finished with Pt/ medium pore zeolite/ Alumina catalyst. Both the low-vis base oil and high-vis base oil fractions show much improved pour and cloud points. The low-vis fraction base oil has excellent Noack volatility, VI and good CCS down to -30 °C.

Example 7-3 was a base oil produced by the exact same oligomerization process as in Examples 7-1 and 7-2 except the hydroisomerization finishing step with another Pt/medium pore zeolite/ Alumina catalyst. Both the low-vis base oil and high-vis base oil fractions show much improved pour and cloud points. The low-vis fraction base oil has excellent Noack volatility, VI and good CCS down to - 30 °C.

In Table 8, we also compared the low-viscosity base oil fraction of Example 7-2 and Example 7-3 with the synthetic 4 cSt PAO obtained from a commercial source (Comparative Example). The low- viscosity base oil fraction of our invention shows much improved pour and cloud points, even though not quite as good as the 4 cSt PAO, while showing better Noack volatility and higher VI than the commercial 4 cSt PAO.

Results from Examples 7-2 and 7-3 suggest that an excellent low-viscosity base oil can be synthesized from high carbon number NAO via oligomerization (dimerization) with an ionic liquid catalyst followed by hydroisomerization with a metal/ zeolite catalyst. Our results indicate that this low-viscosity base oil of our invention is different from the typical PAO and uniquely suited for manufacturing of premium lubricant manufacturing with a new feed source.

Example 8 - Analysis for Molecular Structure of Our Premium Low-Viscosity Base Oil

Compositional analysis of the hydrogenated or hydroisomerized product from Example 7-2 are analyzed using nuclear magnetic resonance spectroscopy (NMR) and reported in Table 9 below (Example 8-3). Also analyzed two other samples finished at lower temperature hydroisomerization where the isomerization was not significant enough to produce good low-viscosity base oil with acceptable low temperature properties. These results are compared with 4 cSt PAO made from 1- decene (1-Cicf) NAO.

Table 9

Relationship Between Average Molecular Structure and Low-Vis Base Oil Properties Comparison of Low-Vis Based Oil from n-Ci ₆ ⁼ NAO with Ionic Liquid Catalyst vs. 4 cSt PAO

Examples 8-1 and 8-2 were finished with hydroisomerization at low temperatures and the low- viscosity base oil properties do not quite meet the targets in Table 1. As the product properties improve (Example 8-3), the oligomer is more isomerized as evidenced by higher branching index, i.e. creation of more methyl branches. The isomerization also lowers the branching proximity and E-CH ₂ carbons. As the Ci ₆ ⁼ dimer is converted under hydroisomerization process using a zeolite catalyst, the linear carbon segments in the molecules are isomerized via migration of methyl groups.

Low-viscosity base oil made from Ci ₆ ⁼ NAO oligomerization is very different form 4 cSt PAO produced from Cio ⁼ NAO, because much longer olefin molecules are used for our process of invention.

Compared with the 4 cSt PAO produced from Cio ⁼ NAO (Comparative Example), the base oil of our invention contains more £CH ₂ , i.e. higher branching proximity and free carbon index (Examples 8-1 and 8-2), which contribute to the higher VI of our process than that of PAO. The commercial 4 cSt PAO was made from Cio NAO, mostly contain trimers and tetramers, intrinsically contains more shorter carbon chains as evidenced with low branching proximity and free carbon index, while the number of methyl branches per molecule (0.9), about the same number as the hydrogenated oligomers from Ci ₆ NAO. As more extensive hydroisomerization is applied during the finishing step (Example 8-3), our low-vis base oil exhibits much lower branching proximity and free carbon index; and higher branching index and higher number of methyl branches per molecule. Example 8-3 made from Ci ₆ NAO now has higher methyl branches per molecules than the 4 cSt PAO made from Cio NAO. This suggests that methyl group migrations are occurring during the hydroisomerization.

Example 9 - Premium Low-Viscosity Base Oil Manufacturing Process for High Yield and Superior Product Properties

The overall process can be further optimized by combing the high conversion and selectivity achieved with the high temperature oligomerization step and the hydroisomerization step using a zeolite catalyst in order to produce very high-quality base oil.

Example 3-5 shown in Table 10 shows base oil properties made from 100 °C oligomerization followed by hydrogenation with Pt, Pd/Alumina catalyst (reference case).

Higher temperature oligomerization at 130 °C and 150 °C were applied to Examples 9-1 through 9-3. In Example 9-1 (reference case), the oligomer was then hydrogenated with a Pt, Pd/Alumina catalyst, while the oligomers in Examples 9-2 and 9-3 (invention) were undergone hydroisomerization finishing step. The process conditions, product yields and property data are summarized in Table 10.

Table 10

Premium Base Oil Manufacturing Process for Superior Product Properties Physical Properties Premium Base Oil Made from Ci ₆ ⁼ NAO

As we have seen in other examples, the hydrogenated Ci ₆ ⁼ oligomers (Examples 3-5 and 9-1) show excellent viscosity index and Noack volatility, but show poor low temperature behaviors (poor pour and cloud points, and poor cold crack simulator viscosity). The hydrogenation finishing step with Pt, Pd/alumina catalyst (no strong acidity) does not crack the oil and the yield of the finished lube yield is about 100% for the hydrogenation step.

The hydroisomerization finishing step with a zeolite catalyst cracks some of hydrocarbon molecules to lighter product (offgas, gasoline and diesel range product) and this is undesirable since it lowers the lube yield. Since the hydrocracking is increased with higher temperature, it is desirable to hydroisomerize at the lowest temperature or mildest condition possible while meeting product requirements.

In example 9-2, with the hydroisomerization finishing at 288 °C, the pour point was lowered further to -47 °C, but the base oil yield was decreased to 92%. In example 9-3, the pour point was lowered to -38 °C by hydroisomerization finishing at 277°C with a base oil yield of 95.9%. Both samples show excellent cold crank simulator (CCS) viscosity at -35°C (1302 and 1428 cP) and mini-rotary viscometer (MRV) viscosity at -40°C (2,006 and 58,557 cP)

Our results in Table 10 indicates that high temperature oligomerization followed by mild hydroisomerization finishing step is an efficient way to synthesize quality low-vis base oil from high molecular weight NAO (C _M - C NAO) while maximize the overall base oil yield and base oil product quality.

Example 10 - Analysis for Molecular Structure of Our Premium Low-Viscosity Base Oil

Compositional analysis of the hydrogenated or hydroisomerized products from Examples 9-1 through 9-3 are analyzed using nuclear magnetic resonance spectroscopy (NMR) and reported in Table 11 below.

Table 11

Relationship Between Average Molecular Structure and Low-Vis Base Oil Properties Comparison of Low-Vis Based Oil from n-Cie ⁼ NAO with Ionic Liquid Catalyst vs. 4 cSt PAO

Low-viscosity base oil made from Ci ₆ ⁼ NAO oligomerization (Example 9-1) contains more £CH ₂ , i.e. higher branching proximity and free carbon index, which contribute to the higher VI but very poor low temperature properties. The 4 cSt PAO was made from Cio NAO, mostly contain trimers and tetramers, intrinsically contains more shorter carbon chains as evidenced with low branching proximity and free carbon index, while the number of methyl branches per molecule (0.9), about the same number as the hydrogenated oligomers from Ci ₆ NAO.

As more extensive hydroisomerization is applied during the finishing step (Examples 9-2 and 9-3), our low-vis base oil exhibits much lower branching proximity and free carbon index; and higher branching index and higher number of methyl branches per molecule. Examples 9-2 and 9-3 made from Ci ₆ NAO now has higher methyl branches per molecules than the 4 cSt PAO made from Cio NAO (2.4 and 2.0 vs. 0.9). This again suggests that methyl group migration is the key mechanism for the product quality improvement. The isomerization occurred both during the high temperature oligomerization and hydroisomerization.

Example 11 - Compositional Analysis for Molecular Structure of Our Premium Low-Viscosity Base Oil

The entire NMR structural data reported in Tables 5, 9 and 11 are plotted in Figures 5 to shows the effects of the molecular structural changes with our process. As we changed the process, (1) oligomerization at higher temperature with preferred ionic catalyst followed by (2) use of finishing hydroisomerization step with metal containing medium pore zeolite catalyst, to produce quality low- viscosity base oil from Ci ₆ NAO monomer, a substantial changes in molecular structure occurred, especially branching proximity, from 33.4 to 18.1.

Each structural parameter (branching index, number of methyl branches per molecule and free carbon index) is plotted against the branching proximity. The results in Figure 5 clearly shows that the molecular structural changes fall in uniform trends and we can clearly differentiate our invention and the preferred invention regions. These plots show the premium low-vis base oil we made from the Ci ₆ NAO is quite different from the composition of commercial 4 cSt PAO made from Cio NAO. Here we are defining the composition of low-vis base oil made by our process.

Viscosity index and pour point of our products in Tables 5, 9 and 11 are plotted in Figures 6 against branching proximity NMR structural data. The results in Figure 6 clearly shows that the low-viscosity base oil property improvement is closely related to the molecular structural changes and we can clearly differentiate our invention and the preferred invention regions. These plots show that the premium low-vis base oil made from Ci ₆ NAO by our process invention is quite different from the composition of commercial 4 cSt PAO made from Cio NAO. Here we are defining the key properties of the low-vis base oil made by our process.

The major drawback of the Ci ₆ dimerization vs. commercial 4 cSt made from Cio trimer was the low temperature performances. With the process of our invention, we overcame the deficiencies of using Ci ₆ NAO and able to produce quality low-vis base oil with excellent low temperature performances as observed in excellent pour and cloud points and CCS and MRV viscosities.