Patent Application
20090062161
This invention is directed to an improved two-cycle gasoline engine lubricant composition requiring reduced amounts of hydrocarbon solvent.
Two-cycle engines have three important advantages over four cycle engines:
There are at least three potential disadvantages of two-cycle engines, including:
The majority of two-cycle gasoline engine lubricants are formulated with low-boiling hydrocarbon solvent and SAE 40 mineral base oils. Others have used ester base oils with no low-boiling solvent to reduce the hazard potential and minimize smoky emissions, however these lubricants do not have very good oxidation stability. Others have used polyalphaolefin base oils having improved low temperature properties, Polyalphaolefin and ester base oils are limited in supply and very expensive. Improved two-cycle gasoline engine lubricant compositions, comprising less expensive base oils, and meeting the requirements set by standard setting organizations are desired. It is also desired that these lubricant compositions have reduced levels of hydrocarbon solvent, reduced engine wear, and reduced, pollution. It is also desired that two-cycle gasoline engine lubricant compositions have good low temperature performance, good gasoline miscibility and high oxidation stability. It is also desired that two-cycle gasoline engine lubricant compositions have higher flash points and reduced flammability. It is also desired that two-cycle gasoline engine lubricant compositions can be made using polyethylene plastic, to reduce waste plastic environmental pollution.
The present invention provides a lubricating oil, comprising:
The present invention also provides a lubricating oil, comprising:
The present invention also provides a lubricating oil, comprising:
The present invention also provides a lubricating oil, comprising:
The present invention also provides a lubricating oil, comprising:
The present invention also provides a lubricating oil, comprising a pour point reducing blend component; wherein the lubricating oil meets the requirements for lubricating oil used in two-cycle gasoline engines according to Japanese Automobile Standard JASO M345:2003.
The present invention also provides a lubricating oil, consisting essentially of:
Noack Volatility Factor (1)=160−40(Kinematic Viscosity at 100° C.), and
Noack Volatility Factor (2)=900×(Kinematic Viscosity at 100° C.)−2.8−15, wherein the Kinematic Viscosity at 100° C. is raised to the power of −2.8 in the second equation.
To operate a two-cycle gasoline engine the crankcase holds a mixture of two-cycle gasoline engine lubricant and fuel. In a two-cycle engine the crankcase is serving as a pressurization chamber to force air/fuel into the cylinder, so it can't hold high viscosity oil like what may be used in a four-cycle engine. Instead, specialized two-cycle gasoline engine lubricant is mixed in with the fuel to lubricate the crankshaft, connecting rod and cylinder walls.
The recommended mix ratio of two-cycle gasoline engine lubricant and fuel are specified by the engine manufacturer. The fuels useful in two-cycle gasoline engines are well known to those skilled in the art and usually contain a major portion of a normally liquid fuel such as a hydrocarbonaceous petroleum distillate fuel, e.g., spark ignition engine fuel as defined by ASTM D4814-07, or motor gasoline as defined by ASTM D439-89. Such fuels can also contain non-hydrocarbonaceous materials such as alcohols, ethers, organo nitro compounds and the like. For example, methanol, ethanol, diethyl ether, methylethyl ether, nitro methane and such fuels are within the scope of this invention as are liquid fuels derived from vegetable and mineral sources such as corn, switch grass, alpha shale and coal. Examples of such fuel mixtures are combinations of gasoline and ethanol, diesel fuel and ether, gasoline and nitro methane, etc. In one embodiment the fuel is lead-free gasoline.
Two-cycle gasoline engine lubricants are used in admixture with fuels in amounts of about 20 to 250 parts by weight of fuel per 1 part by weight of lubricating oil, more typically about 30-100 parts by weight of fuel per 1 part by weight of lubricant.
Two-cycle gasoline engine lubricants must meet requirements set by standards setting organizations, including Japanese Automobile Standard JASO M345:2003 and International Standard ISO 13738:2000(E). The requirements of these two standards are summarized in the table below.
The indexes in the table of requirements above are determined by taking JATRE-1 oil as having a value of 100. Classification C applies to what is called low-smoke type oil that has superior exhaust smoke performance and exhaust system blocking tendency. Classification D is applied to Oils with better detergency than Classification C oils when the engine is hot.
Classification B, C and D oils in the ISO standard all have a sulfated ash content of 0.18 wt % maximum. Sulfated ash may be measured according to ISO 3987 or ASTM D874-00.
Additionally, it is desired that these lubricants have good low temperature fluidity when they are to be used in conditions where low temperatures are encountered. Low temperature fluidity is measured by determining the Brookfield Viscosity measured by ASTM D2983-04a at defined temperatures of −10° C., −25° C. and −40° C. “Good low temperature fluidity” at one of the temperatures measured is defined in this disclosure as when the oil being tested has a Brookfield Viscosity of about 7500 mPa·s or less. For example, good low temperature fluidity at 10° C. means that the oil has a Brookfield Viscosity at −10° C. of about 7500 mPa·s or less; good low temperature fluidity at −25° C. means that the oil has a Brookfield Viscosity at −25° C. of about 7500 mPa·s or less; and good low temperature fluidity at −40° C. means that the oil has a Brookfield Viscosity at −40° C. of about 7500 mPa·s or less.
Additionally, it is desired that these lubricants have passing results in the miscibility test by ASTM D4682-87 (Reapproved 2002) at temperatures of −10° C. and/or −25° C.
The two-cycle gasoline engine lubricant compositions are particularly suited as injector oils or at up to a 150:1 fuel to lubricant mix ratio with an appropriate fuel such as gasoline in carbureted, electronic fuel injected and direct fuel injected two-cycle engines, including: outboard motors, snowmobiles, motorcycles, mopeds, ATVs, golf carts, lawn mowers, chain saws, string trimmers and the like.
The lubricant base oils used in the two-cycle gasoline engine lubricant compositions are derived from substantially paraffinic waxy feeds. The term “substantially paraffinic” means containing a high level of n-paraffins, generally greater than 40 wt %. Some substantially paraffinic waxy feeds may have for example greater than 50 wt %, or greater than 75 wt % n-paraffins. One example of a substantially paraffinic waxy feed is wax produced in a Fischer-Tropsch process. Another example is highly refined slack wax.
Fischer-Tropsch waxes can be obtained by well-known processes such as, for example, the commercial SASOL® Slurry Phase Fischer-Tropsch technology, the commercial SHELL® Middle Distillate Synthesis (SMDS) Process or by the non-commercial EXXON® Advanced Gas Conversion (AGC-21) process. Details of these processes and others are described in, for example, EP-A-776959, EP-A-668342; U.S. Pat. Nos. 4,943,672, 5,059,299, 5,733,839, and RE39073, and US Published Application No. 2005/0227866, WO-A-9934917, WO-A-9920720 and WO-A-05107935. The Fischer-Tropsch synthesis product usually comprises hydrocarbons having 1 to 100, or even more than 100 carbon atoms, and typically includes paraffins, olefins and oxygenated products. Fischer Tropsch is a viable process to generate clean alternative hydrocarbon products, including Fischer-Tropsch waxes.
Slack wax can be obtained from conventional petroleum derived feedstocks by either hydrocracking or by solvent refining of the lube oil fraction. Typically, stack wax is recovered from solvent dewaxing feedstocks prepared by one of these processes. Hydrocracking is usually preferred because hydrocracking will also reduce the nitrogen content to a low value. With slack wax derived from solvent refined oils, deoiling may be used to reduce the nitrogen content and raise the viscosity index. Hydrotreating of the slack wax can be used to lower the nitrogen and sulfur content. Slack waxes posses a very high viscosity index, normally in the range of from about 140 to 200, depending on the oil content and the starting material from which the slack wax was prepared. Therefore, slack waxes are suitable for the preparation of base oils used in two-cycle gasoline engine lubricants.
In one embodiment the waxy feed has less than 25 ppm total combined nitrogen and sulfur. Nitrogen is measured by melting the waxy feed prior to oxidative combustion and chemiluminescence detection by ASTM D 4629-02. The test method is further described in U.S. Pat. No. 6,503,956, incorporated herein. Sulfur is measured by melting the waxy feed prior to ultraviolet fluorescence by ASTM D 5453-00. The test method is further described in U.S. Pat. No. 6,503,956, incorporated herein.
Determination of normal paraffins (n-paraffins) in wax-containing samples should use a method that can determine the content of individual C7 to C110 n-paraffins with a limit of detection of 0.1 wt %. The method used is described later in this disclosure.
Waxy feeds are expected to be plentiful and relatively cost competitive in the near future as large-scale Fischer-Tropsch synthesis processes come into production. Fischer-Tropsch derived base oils made from these waxy feeds, and thus the two-cycle gasoline engine lubricants comprising them, will be less expensive than lubricants made with other synthetic oils such as polyalphaolefins or esters. The terms “Fischer-Tropsch derived” or “FT derived” means that the product, fraction, or feed originates from or is produced at some stage by a Fischer-Tropsch process. The feedstock for a Fischer-Tropsch process may come from a wide variety of hydrocarbonaceous resources, including biomass, natural gas, coal, shale oil, petroleum, municipal waste, derivatives of these, and combinations thereof. Syncrude prepared from the Fischer-Tropsch process comprises a mixture of various solid, liquid, and gaseous hydrocarbons. Those Fischer-Tropsch products which boil within the range of lubricating base oil contain a high proportion of wax which makes them ideal candidates for processing into base oil. Accordingly, Fischer-Tropsch wax represents an excellent feed for preparing high quality base oils. Fischer-Tropsch wax is normally solid at room temperature and, consequently, displays poor low temperature properties, such as pour point and cloud point. However, following hydroisomerization of the wax, Fischer-Tropsch derived base oils having excellent low temperature properties may be prepared. A general description of examples of suitable hydroisomerization dewaxing processes may be found in U.S. Pat. Nos. 5,135,638 and 5,282, 958; and US Patent Application 20050133409, incorporated herein.
The hydroisomerization is achieved by contacting the waxy feed with a hydroisomerization catalyst in an isomerization zone under hydroisomerizing conditions. The hydroisomerization catalyst preferably comprises a shape selective intermediate pore size molecular sieve, a noble metal hydrogenation components, and a refractory oxide support. The shape selective intermediate pore size molecular sieve is preferably selected from the group consisting of SAPO-11, SAPO-31 SAPO-41, SM-3, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, ferrierite, and combinations thereof. SAPO-11, SM-3, SZZ-32, ZSM-23, ZSM-48, and combinations thereof are used in one embodiment. In one embodiment the noble metal hydrogenation component is platinum, palladium, or combinations thereof.
The hydroisomerizing conditions depend on the waxy feed used, the hydroisomerization catalyst used, whether or not the catalyst is sulfided, the desired yield, and the desired properties of the base oil. Examples of hydroisomerizing conditions of one embodiment include temperatures of 260 degrees C. to about 413 degrees C. (500 to about 775 degrees F); a total pressure of 15 to 3000 psig, or 50 to 1000 psig; and a hydrogen to feed ratio from about 2 to 30 MSCF/bbl, about 4 to 20 MSCF/bbl (about 712.4 to about 3562 liter H2/liter oil), about 4.5 or 5 to about 10 MSCF/bbl, or about 5 to about 8 MSCF/bbl. Generally, hydrogen will be separated from the product and recycled to the isomerization zone. Note that a feed rate of 10 MSCF/bbl is equivalent to 1781 liter H2/liter feed. Generally, hydrogen will be separated from the product and recycled to the isomerization zone.
Optionally, the base oil produced by hydroisomerization dewaxing may be hydrofinished. The hydrofinishing may occur in one or more steps, either before or after fractionating of the base oil into one or more fractions. The hydrofinishing is intended to improve the oxidation stability, UV stability, and appearance of the product by removing aromatics, olefins, color bodies, and solvents. A general description of hydrofinishing may be found in U.S. Pat. Nos. 3,852,207 and 4,673,487, incorporated herein. The hydrofinishing step may be needed to reduce the weight percent olefins in the base oil to less than 10, less than 5 or 2, less than 1, less than 0.5, and less than 0.05 or 0.01. The hydrofinishing step may also be needed to reduce the weight percent aromatics to less than 0.3 or 0.1, less than 0.05, less than 0.02, and in some embodiments even less than 0.01.
Optionally, the base oil produced by hydroisomerization dewaxing may be treated with an adsorbent such as bauxite or clay to remove impurities and improve the color and biodegradability.
Because it is made from a waxy feed, the base oil has consecutive numbers of carbon atoms. By “consecutive numbers of carbon atoms” we mean that the hydrocarbon molecules of the base oil differ from each other by consecutive numbers of carbon atoms, as a consequence of the waxy feed also having sequential numbers of carbon atoms. For example, in the Fischer-Tropsch hydrocarbon synthesis reaction the source of carbon atoms is CO and the hydrocarbons molecules are built up one carbon atom at a time. Petroleum-derived waxy feeds also have sequential numbers of carbon numbers. In contrast to an oil based on PAO, the molecules of the base oil have a more linear structure, comprising a relatively long backbone with short branches. The classic textbook description of a PAO is a star-shaped molecule, and in particular tridecane, which is illustrated as three decane molecules attached at a central point. While a star-shaped molecule is theoretical, nevertheless PAO molecules have fewer and longer branches that the hydrocarbon molecules that make up the base oil used in this disclosure. In another embodiment the base oil having consecutive numbers of carbon atoms also has less than 10 wt % naphthenic carbon by n-d-M.
In one embodiment the lubricating base oil is separated into fractions, whereby one or more of the fractions will have a pour point less than 0° C., less than −9° C., less than −15° C., less than −20° C., less than −30° C., or less than −35° C. Pour point is measured by ASTM D 5950-02. The base oil is optionally fractionated into different viscosity grades of base oil. In the context of this disclosure “different viscosity grades of base oil” is defined as two or more base oils differing in kinematic viscosity at 100 degrees C. from each other by at least 0.5 mm2/s. Kinematic viscosity is measured using ASTM D445-06. Fractionating is done using a vacuum distillation unit to yield cuts with pre selected boiling ranges. One of the fractions may be a distillation bottoms product.
In one embodiment the base oil fractions have less than 0.01 wt % aromatic carbon and greater than about 90 wt % paraffinic carbon. The balance of the wt % carbon is naphthenic carbon. Wt % aromatic, wt % paraffinic and wt % naphthenic carbon are determined by n-d-M analysis according to ASTM D3238-95(2005). In one embodiment the wt % paraffinic carbon is between about 90 wt % and about 97 wt % and the wt % naphthenic carbon is between about 3 wt % and about 10 wt %.
In one embodiment, the viscosity indexes of the lubricating base oil fractions will be high. They will often have viscosity indexes greater than 28×Ln(Kinematic Viscosity at 100° C.)+80. In one embodiment they will have viscosity indexes greater than 28×Ln(Kinematic Viscosity at 100° C.)+95. For example a 2.5 mm2 oil have a viscosity index greater than 106, optionally greater than 121; and a 12 mm2/s oil will have a viscosity index greater than 150, optionally greater than 165.
In another embodiment the base oil has a pour point of less than −8° C.; a kinematic viscosity at 100° C. of at least 1.5 mm2/s; and a viscosity index greater than an amount calculated by the equations 22×Ln (Kinematic Viscosity at 100° C.)+132. In this embodiment, for example, an oil with a kinematic viscosity of 2.5 mm2/s at 100° C. will have a viscosity index greater than 152. Base oils with these properties are described in US Patent Publication US20050077208. The term “Ln” in the context of equations in this disclosure refers to the natural logarithm with base ‘e’. The test method used to measure viscosity index is ASTM D 2270-04.
The base oil fractions have a kinematic viscosity at 100° C. between about 1.3 and 25 mm2/s. In one embodiment the base oil fractions have a kinematic viscosity at 100° C. between about 1.5 and about 3.5 mm2/s. In another embodiment the base oil fractions have a kinematic viscosity between about 1.8 and about 3.2 mm2/s.
In one embodiment the base oil fractions provide excellent oxidation stability, low Noack volatility, as well as desired additive solubility and elastomer compatibility. The base oil fractions have a weight percent olefins less than 10, less than 5, less than 1, less than 0.5, or less than 0.05 or 0.01. The base oil fractions have a weight percent aromatics less than 0.1, less than 0.05, or less than 0.02.
“Traction coefficient” is an indicator of intrinsic lubricant properties, expressed as the dimensionless ratio of the friction force F and the normal force N, where friction is the mechanical force which resists movement or hinders movement between sliding or rolling surfaces. Traction coefficient can be measured with an MTM Traction Measurement System from PCS Instruments, Ltd., configured with a polished 19 mm diameter ball (SAE AISI 52100 steel) angled at 220 to a flat 46 mm diameter polished disk (SAE AISI 52100 steel). The steel ball and disk are independently measured at an average rolling speed of 3 meters per second, a slide to roll ratio of 40 percent, and a load of 20 Newtons. The roll ratio is defined as the difference in sliding speed between the ball and disk divided by the mean speed of the ball and disk, i.e. roll ratio=(Speed1−Speed2)/((Speed1+Speed2)−/2). In some embodiments, the base oil fractions have a traction coefficient less than 0.023, less than or equal to 0.021, or less than or equal to 0.019, when measured at a kinematic viscosity of 15 mm2/s and at a slide to roll ratio of 40 percent. In one embodiment they have a traction coefficient less than an amount defined by the equation traction coefficient=0.009×Ln(Kinematic Viscosity)−0.001, wherein the Kinematic Viscosity during the traction coefficient measurement is between 2 and 50 mm2/s; and wherein the traction coefficient is measured at an average rolling speed of 3 meters per second, a slide to roll ratio of 40 percent, and a load of 20 Newtons.
In one embodiment the base oil fractions have a traction coefficient less than 0.015 or less than 0.011, when measured at a kinematic viscosity of 15 mm2/s and at a slide to roll ratio of 40 percent. Examples of these base oil fractions with low traction coefficients are taught in U.S. Pat. No. 7,045,055 and U.S. patent application Ser. Nos. 11/400,570 and 11/399,773 both filed Apr. 7, 2006. In one embodiment, the base oil has a traction coefficient less than 0.015, and a 50 wt % boiling point greater than 565° C. (1050° F.). In another embodiment, the base oil has a traction coefficient less than 0.011 and a 50 wt % boiling point by ASTM D 6352-04 greater than 582° C. (1080° F.).
In some embodiments, the isomerized base oil having a low traction coefficient also displays unique branching properties by NMR, including a branching index less than or equal to 23.4, a branching proximity greater than or equal to 22.0, and a Free Carbon Index between 9 and 30. In one embodiment, the base oil has at least 4 wt % naphthenic carbon, in another embodiments at least 5 wt % naphthenic carbon by n-d-M analysis by ASTM D 3238-95 (Reapproved 2005). Two-cycle gasoline engine lubricants made comprising base oil fractions having low traction coefficients provide reduced engine wear.
In some embodiments, where the olefin and aromatics contents are significantly low in the lubricant base oil fraction of the lubricating oil, the Oxidator BN of the selected base oil fraction will be greater than 25 hours, such as greater than 35 hours or even greater than 40 hours. The Oxidator BN of the selected base oil fraction will typically be less than 70 hours. Oxidator BN is a convenient way to measure the oxidation stability of base oils. The Oxidator BN test is described by Stangeland et al. in U.S. Pat. No. 3,852,207. The Oxidator BN test measures the resistance to oxidation by means of a Dornte-type oxygen absorption apparatus, See R. W. Dornte “Oxidation of White Oils,” Industrial and Engineering Chemistry, Vol. 28, page 26, 1936. Normally, the conditions are one atmosphere of pure oxygen at 340° F. The results are reported in hours to absorb 1000 m of O2 by 100 g. of oil. In the Oxidator BN test, 0.8 ml of catalyst is used per 100 grams of oil and an additive package is included in the oil. The catalyst is a mixture of soluble metal naphthenates in kerosene. The mixture of soluble metal naphthenates simulates the average metal analysis of used crankcase oil. The level of metals in the catalyst is as follows: Copper=6,927 ppm; Iron=4,083 ppm; Lead=80,208 ppm; Manganese=350 ppm, Tin=3565 ppm. The additive package is 80 millimoles of zinc bispolypropylenephenyldithio-phosphate per 100 grams of oil, or approximately 1.1 grams of OLOA™ 260. The Oxidator BN test measures the response of a lubricating base oil in a simulated application. High values, or long times to absorb one liter of oxygen, indicate good oxidation stability. Two-cycle gasoline engine lubricants comprising base oil fractions having good oxidation stability will also have improved oxidation stability.
OLOA™ is an acronym for Oronite Lubricating Oil Additive, which is a registered trademark of Chevron Oronite.
In some embodiments the one or more lubricating base oil fractions will have excellent biodegradability. With suitable hydro-processing and/or adsorbent treatment they are readily biodegradable by the OECD 301B Shake Flask Test (Modified Sturm Test). When the readily biodegradable base oil fractions are blended with suitable biodegradable additives, such as selected low-ash or ashless additives, the lubricants will provide rapid biodegradation of spills in sensitive areas with minimal non-biodegradable residue and will prevent costly environmental clean-up.
In some embodiments the one or more lubricating base oil fractions will have a low Noack volatility. Noack volatility is usually tested according to ASTM D5800-05 Procedure B. In an embodiment the one or more lubricating base oil fractions have a Noack volatility of less than 100 weight %. Noack volatility of base oils generally increases as the kinematic viscosity decreases. The lower the Noack volatility, the lower the tendency of base oil and formulated oils to volatilize in service.
The “Noack Volatility Factor” of base oil is an empirical number derived from the kinematic viscosity of the base oil. The Noack volatility of the base oil derived from highly paraffinic wax is very low, and in an embodiment, is less than an amount calculated by the equation:
Noack Volatility Factor (1)=160−40(Kinematic Viscosity at 100° C.).
Equation (1), as provided in U.S. Patent Application Publication No. 2006/0201852 A1, provides Noack Volatility Factors between 0 and 100 for kinematic viscosities between 1.5 and 4.0 mm2/s.
Noack Volatility Factor (2)=(900×(kinematic Viscosity at 100° C.)2.8)−15.
Equation (2), as provided in U.S. patent application Ser. No. 11/613,936, provides Noack Volatility Factors between 0 and 100 for kinematic viscosities between 2.09 and 4.3 mm2/s.
Additional base oils may be incorporated in the lubricant composition in an amount from about 1.0 wt % to about 20 wt %. Examples of these additional base oils include esters, mixtures of esters, and complex esters as described in U.S. Pat. No. 6,197,731; polyalphaolefins, polyinternalolefins, polyisobutenes, alkylated aromatics such as alkylated naphthalenes, and conventional petroleum derived API Group II and Group III mineral oils.
The two-cycle gasoline engine lubricant may comprise a pour point reducing blend component. As used herein, “pour point reducing blend component” refers to an isomerized waxy product with relatively high molecular weight and a specified degree of alkyl branching in the molecules, such that it reduces the pour point of lubricating base oil blends containing it. Examples of a pour point reducing blend component are disclosed in U.S. Pat. Nos. 6,150,577 and 7,053,254, and Patent Publication No. US 20050247600 A1. A pour point reducing blend component can be: 1) an isomerized Fischer-Tropsch derived bottoms product; 2) a bottoms product prepared from an isomerized highly waxy mineral oil, or 3) an isomerized oil having a kinematic viscosity at 100° C. of at least about 8 mm2/s made from polyethylene plastic.
In one embodiment, the pour point reducing blend component is an isomerized Fischer-Tropsch derived vacuum distillation bottoms product having an average molecular weight between 600 and 1100 and an average degree of branching in the molecules between 6.5 and 10 alkyl branches per 100 carbon atoms. Generally, the higher molecular weight hydrocarbons are more effective as pour point reducing blend components than the lower molecular weight hydrocarbons. In one embodiment a higher cut point in a vacuum distillation unit which results in a higher boiling bottoms material is used to prepare the pour point reducing blend component. The higher cut point also has the advantage of resulting in a higher yield of the distillate base oil fractions. In one embodiment, the pour point reducing blend component is an isomerized Fischer-Tropsch derived vacuum distillation bottoms product having a pour point that is at least 3° C. higher than the pour point of the distillate base oil it is blended with.
In one embodiment, the 10 percent point of the boiling range of the pour point reducing blend component that is a vacuum distillation bottoms product is between about 850° F.-1050° F. (454-565° C.). In another embodiment, the pour point reducing blend component is derived from either Fischer-Tropsch or petroleum products, having a boiling range above 950° F. (510° C.), and contains at least 50 percent by weight of paraffins. In yet another embodiment the pour point reducing blend component has a boiling range above 1050° F. (565° C.).
In another embodiment, the pour point reducing blend component is an isomerized petroleum derived base oil containing material having a boiling range above about 1050° F. In one embodiment, the isomerized bottoms material is solvent dewaxed prior to being used as a pour point reducing blend component. The waxy products further separated during solvent dewaxing from the pour point reducing blend component were found to display excellent improved pour point depressing properties compared to the oily product recovered after the solvent dewaxing.
In another embodiment, the pour point reducing blend components is an isomerized oil having a kinematic viscosity at 100° C. of at least about 8 mm2/s made from polyethylene plastic. In one embodiment the pour point reducing blend component is made from waste plastic. In another embodiment the pour point reducing blend component is made from steps comprising pyrolysis of polyethylene plastic, separating out a heavy fraction, hydrotreating the heavy fraction, catalytic isomerizing the hydrotreated heavy fraction, and collecting the pour point reducing blend component having a kinematic viscosity at 100° C. of at least about 8 mm2 is. In a third embodiment, the pour point reducing blend component derived from polyethylene plastic and has a boiling range above 1050° F. (565° C.), or even has a boiling range above 1200° F. (649° C.).
In one embodiment, the pour point reducing blend component has an average degree of branching in the molecules within the range of from 6.5 to 10 alkyl branches per 100 carbon atoms. In another embodiment, the pour point reducing blend component has an average molecular weight between 600-1100. In a third embodiment it has an average molecular weight between 700-1000. In one embodiment, the pour point reducing blend component has a kinematic viscosity at 100° C. of 8-30 mm2/s, with the 10% point of the boiling range falling between about 850-1050° F. In yet another embodiment, the pour point reducing blend component has a kinematic viscosity at 100° C. of 15-20 mm2/s and a pour point of −8 to −12° C.
In one embodiment, the pour point reducing blend component is an isomerized oil having a kinematic viscosity at 100° C. of at least about 8 mm2/s made from polyethylene plastic. In one embodiment the pour point reducing blend component is made from waste plastic. In another embodiment the pour point reducing blend component is made from steps comprising pyrolysis of polyethylene plastic, separating out a heavy fraction, hydrotreating the heavy fraction, catalytic isomerizing the hydrotreated heavy fraction, and collecting the pour point reducing blend component having a kinematic viscosity at 100° C. of at least about 8 mm2/s. In a third embodiment, the pour point reducing blend component derived from polyethylene plastic has a boiling range above 1050° F. (565° C.), or even a boiling range above 1200° F. (649° C.).
Various detergent/dispersant additive packages may be combined with base oil in formulating two-cycle oil gasoline engine lubricants. Ashless, low-ash, or ash-containing additives may be used for this purpose.
Suitable ashless additives include polyamide, alkenylsuccinimides, boric acid-modified alkenylsuccinimides, phenolic amines and succinate derivatives or combinations of any two or more of such additives.
Examples of a low ash additive package comprise (i) polyisobutenyl (Mn 400-2500) succinimide or another oil soluble, acylated, nitrogen containing lubricating oil dispersant present in the amount of 0.2-5 wt. % in the lubricating oil and (ii) a metal phenate, sulfonate or salicylate oil soluble detergent additive. In one embodiment, the oil soluble detergent additive is a neutral metal detergent or overbased metal detergent of Total Base Number 200 or less, present in the amount of 0.1-2 wt % in the lubricating oil. In this embodiment the metal is calcium, barium or magnesium. Neutral calcium salicylates are one example, and may be present in amounts of about 0.5 to 1.5 wt % in the lubricating oil.
Polyamide detergent/dispersant additives, such as the commonly used tetraethylenepentamine isostearate, may be prepared by the reaction of fatty acid and polyalkylene polyamines, as described in U.S. Pat. No. 3,169,980, the entire disclosure of which is incorporated by reference in this specification, as if set forth herein in full. These polyamides may contain measurable amounts of cyclic imidazolines formed by internal condensation of the linear polyamides upon continued heating at elevated temperature.
Another useful class of polyamide additives is prepared from polyalkylene polyamines and C19-C25 Koch acids, according to the procedure of R. Hartle et al., JAOCS, 57 (5): 156-59 (1980). Alkenylsuccinimides are formed by a step-wise procedure in which an olefin, such as polybutene (MV 1200) is reacted with maleic anhydride to yield a polybutenyl succinic anhydride adduct, which is then reacted with an amine, e.g., an alkylamine or a poly-amine, to form the desired product.
Phenolic amines are prepared by the well-known Mannich reaction (C. Mannich and W. Krosche, Arch. Pharm., 250: 674 (1912)), involving a polyalkylene-substituted phenol, formaldehyde and a polyalkylene polyamine.
Succinate derivatives are prepared by the reaction of an olefin (e.g., polybutene (eg., polybutene) and maleic anhydride to yield a polybutenyl succinic anhydride adduct, which undergoes further reaction with a polyol, e.g., pentaerythritol, to give the desired product.
Suitable ash-containing detergent/dispersant additives include alkaline earth metal (e.g., magnesium, calcium, barium), sulfonates, phosphonates or phenates or combinations of any two or more of such additives.
The foregoing detergent/dispersant additives may be incorporated in the lubricant compositions described herein in an amount from about 1 to about 25 wt %, and more preferably from about 3 to about 20 wt % based on the total weight of the composition.
Commercially available two-cycle lubricant detergent/dispersant additive packages may be used in combination with the base oil to produce the two-cycle gasoline engine lubricant, for example, LUBRIZOL 400, LUBRIZOL 6827, LUBRIZOL 6830, LUBRIZOL 600, LUBRIZOL 606, ORONITE OLOA® 9333, ORONITE OLOA® 340A, ORONITE OLOA® 6721 and ORONITE OLOA® 9357.
Various other additives may be incorporated in the two-cycle gasoline engine lubricant, as desired. These include smoke-suppression agents, such as polybutene or polyisobutylene (PIB), extreme pressure additives, such as dialkyldithiophosphoric acid salts or esters, anti-foaming agents, such as silicone oil, pour point depressants, rust or corrosion prevention agents, such as triazole derivatives, propyl gallate or alkali metal phenolates or sulfonates, oxidation inhibitors, such as substituted diarylamines, phenothiazines, hindered phenols, or the like. Certain of these additives may be multifunctional, such as polymethacrylate, which may serve as an anti-foaming agent, as well as a pour point depressant. Pour point depressants, when used, are used in an amount between 0.005 to 0.1 wt % based on the total lubricating oil. Examples of pour point depressants are polymethacrylates (PMA); polyacrylates; polyacrylamides; condensation products of haloparaffin waxes and aromatic compounds; vinyl carboxylate polymers; terpolymers of dialkylfumarates, vinyl esters of fatty acids, and alkyl vinyl ethers; and mixtures thereof.
In one embodiment, the smoke-suppression agent is an olefinically unsaturated polymer selected from the group consisting of polybutene, polyisobutylene or a mixture of polybutene and polyisobutylene, which has a number average molecular weight of 400 to 2200 and a terminal vinylidene content of at least 60 mol %, based on the total number of double bonds in the polymer. These types of smoke-suppression agents are taught in EP174393A2. A commercial example of these smoke-suppression agents is BASF Corporation's GLISSOPAL®1000.
Volatile, combustible high flash hydrocarbon solvent such as kerosene, Exxsol D80, or Stoddard solvent can also be used as additives. Exxsol D80 is a dearomatized aliphatic high flash solvent with an initial boiling point of at least 200° C. a Kauri-Butanol Value of about 28 (between 20 and 40), and an aniline point of 73.9 to 79.4° C. Volatile, combustible high flash hydrocarbon solvents may be added to the two-cycle engine lubricant in an amount less than 5 wt % of the total lubricating oil in order to bring the smoke index to a value of at least 75 in the JASO M 342-92 test and/or to improve the compatibility and/or solubility of other additives and to improve the low temperature characteristics such as viscosity and gasoline miscibility. In one embodiment, the two-cycle gasoline engine lubricant comprises low levels of solvents such as less than about 5 wt %, less than about 2 wt %, or even essentially none of the total lubricating oil is a hydrocarbon solvent having a maximum boiling point less than 250 degrees C. Lower levels of solvent in the two-cycle gasoline engine lubricant provides for reduced pollution by evaporation of volatile organic contents, improved compatibility with elastomers used in packaging and transport, and reduced flammability hazards for enhanced transportation and storage safety.
Most of the above-described additives may be incorporated in the lubricant composition in an amount from about 0.005% to about 15%, or from about 0.005% to about 6%, based on the total weight of the lubricant composition. In the case of polybutene or polyisobutylene, the amount may vary from 1% to 50%. The amount of each additive or additive package selected within the specified range should be such as not to adversely effect the desirable performance properties of the lubricant. The effects produced by such additives can be readily determined by routine testing.
Alternatively, the lubricating oil is one consisting of, or consisting essentially of:
The two-cycle gasoline engine lubricants have high flash points due to the low level of solvent they contain. Their flash points are in some embodiments greater than 120° C., or greater than 150° C.
Quantitative analysis of normal paraffins in wax-containing samples is determined by gas chromatography (GC). The GC (Agilent 6890 or 5890 with capillary split/splitless inlet and flame ionization detector) is equipped with a flame ionization detector, which is highly sensitive to hydrocarbons. The method utilizes a methyl silicone capillary column, routinely used to separate hydrocarbon mixtures by boiling point. The column is fused silica, 100% methyl silicone, 30 meters length, 0.25 mm ID, 0.1 micron film thickness supplied by Agilent. Helium is the carrier gas (2 ml/min) and hydrogen and air are used as the fuel to the flame.
The waxy feed is melted to obtain a 0.1 g homogeneous sample. The sample is immediately dissolved in carbon disulfide to give a 2 wt % solution. If necessary, the solution is heated until visually clear and free of solids, and then injected into the GC. The methyl silicone column is heated using the following temperature program:
The column then effectively separates, in the order of rising carbon number, the normal paraffins from the non-normal paraffins. A known reference standard is analyzed in the same manner to establish elution times of the specific normal-paraffin peaks. The standard is ASTM D2887 n-paraffin standard, purchased from a vendor (Agilent or Supelco), spiked with 5 wt % Polywax 500 polyethylene (purchased from Petrolite Corporation in Oklahoma). The standard is melted prior to injection. Historical data collected from the analysis of the reference standard also guarantees the resolving efficiency of the capillary column.
If present in the sample, normal paraffin peaks are well separated and easily identifiable from other hydrocarbon types present in the sample. Those peaks eluting outside the retention time of the normal paraffins are called non-normal paraffins. The total sample is integrated using baseline hold from start to end of run. N-paraffins are skimmed from the total area and are integrated from valley to valley. All peaks detected are normalized to 100%. EzChrom is used for the peak identification and calculation of results.
The Wt % Olefins in the base oils is determined by proton-NMR by the following steps, A-D:
The wt % olefins by proton NMR calculation procedure, D, works best when the % olefins result is low, less than about 15 weight percent. The olefins must be “conventional” olefins; i.e. a distributed mixture of those olefin types having hydrogens attached to the double bond carbons such as: alpha, vinylidene, cis, trans, and trisubstituted. These olefin types will have a detectable allylic to olefin integral ratio between 1 and about 2.5. When this ratio exceeds about 3, it indicates a higher percentage of tri or tetra substituted olefins are present and that different assumptions must be made to calculate the number of double bonds in the sample.
The method used to measure low levels of molecules with at least one aromatic function in the lubricant base oils uses a Hewlett Packard 1050 Series Quaternary Gradient High Performance Liquid Chromatography (HPLC) system coupled with a HP 1050 Diode-Array UV-Vis detector interfaced to an HP Chem-station. Identification of the individual aromatic classes in the highly saturated Base oils was made on the basis of their UV spectral pattern and their elution time. The amino column used for this analysis differentiates aromatic molecules largely on the basis of their ring-number (or more correctly, double-bond number). Thus, the single ring aromatic containing molecules elute first, followed by the polycyclic aromatics in order of increasing double bond number per molecule. For aromatics with similar double bond character, those with only alkyl substitution on the ring elute sooner than those with naphthenic substitution.
Unequivocal identification of the various base oil aromatic hydrocarbons from their UV absorbance spectra was accomplished recognizing that their peak electronic transitions were all red-shifted relative to the pure model compound analogs to a degree dependent on the amount of alkyl and naphthenic substitution on the ring system. These bathochromic shifts are well known to be caused by alkyl-group delocalization of the π-electrons in the aromatic ring. Since few unsubstituted aromatic compounds boil in the lubricant range, some degree of red-shift was expected and observed for all of the principle aromatic groups identified.
Quantitation of the eluting aromatic compounds was made by integrating chromatograms made from wavelengths optimized for each general class of compounds over the appropriate retention time window for that aromatic. Retention time window limits for each aromatic class were determined by manually evaluating the individual absorbance spectra of eluting compounds at different times and assigning them to the appropriate aromatic class based on their qualitative similarity to model compound absorption spectra. With few exceptions, only five classes of aromatic compounds were observed in highly saturated API Group II and III lubricant base oils.
HPLC-UV is used for identifying these classes of aromatic compounds even at very low levels. Multi-ring aromatics typically absorb 10 to 200 times more strongly than single-ring aromatics. Alkyl-substitution also affected absorption by about 20%. Therefore, it is important to use HPLC to separate and identify the various species of aromatics and know how efficiently they absorb.
Five classes of aromatic compounds were identified. With the exception of a small overlap between the most highly retained alkyl-1-ring aromatic naphthenes and the least highly retained alkyl naphthalenes, all of the aromatic compound classes were baseline resolved. Integration limits for the co-eluting 1-ring and 2-ring aromatics at 272 nm were made by the perpendicular drop method. Wavelength dependent response factors for each general aromatic class were first determined by constructing Beer's Law plots from pure model compound mixtures based on the nearest spectral peak absorbances to the substituted aromatic analogs.
For example, alkyl-cyclohexylbenzene molecules in base oils exhibit a distinct peak absorbance at 272 nm that corresponds to the same (forbidden) transition that unsubstituted tetralin model compounds do at 268 nm. The concentration of alkyl-1-ring aromatic naphthenes in base oil samples was calculated by assuming that its molar absorptivity response factor at 272 nm was approximately equal to tetralin's molar absorptivity at 268 nm, calculated from Beer's law plots. Weight percent concentrations of aromatics were calculated by assuming that the average molecular weight for each aromatic class was approximately equal to the average molecular weight for the whole base oil sample.
This calibration method was further improved by isolating the 1-ring aromatics directly from the lubricant base oils via exhaustive HPLC chromatography. Calibrating directly with these aromatics eliminated the assumptions and uncertainties associated with the model compounds. As expected, the isolated aromatic sample had a lower response factor than the model compound because it was more highly substituted.
More specifically, to accurately calibrate the HPLC-UV method, the substituted benzene aromatics were separated from the bulk of the lubricant base oil using a Waters semi-preparative HPLC unit. 10 grams of sample was diluted 1:1 in n-hexane and injected onto an amino-bonded silica column, a 5 cm×22.4 mm ID guard, followed by two 25 cm×242.4 mm ID columns of 8-12 micron amino-bonded silica particles, manufactured by Rainin Instruments, Emeryville, Calif., with n-hexane as the mobile phase at a flow rate of 18 mls/min. Column eluent was fractionated based on the detector response from a dual wavelength UV detector set at 265 nm and 295 nm. Saturate fractions were collected until the 265 nm absorbance showed a change of 0.01 absorbance units, which signaled the onset of single ring aromatic elution. A single ring aromatic fraction was collected until the absorbance ratio between 265 nm and 295 nm decreased to 2.0, indicating the onset of two ring aromatic elution. Purification and separation of the single ring aromatic fraction was made by re-chromatographing the monoaromatic fraction away from the “tailing” saturates fraction which resulted from overloading the HPLC column.
This purified aromatic “standard” showed that alkyl substitution decreased the molar absorptivity response factor by about 20% relative to unsubstituted tetralin.
The weight percent of all molecules with at least one aromatic function in the purified mono-aromatic standard was confirmed via long-duration carbon 13 NMR analysis. NMR was easier to calibrate than HPLC UV because it simply measured aromatic carbon so the response did not depend on the class of aromatics being analyzed. The NMR results were translated from % aromatic carbon to % aromatic molecules (to be consistent with HPLC-UV and D 2007) by knowing that 95-99% of the aromatics in highly saturated lubricant base oils were single-ring aromatics.
High power, long duration, and good baseline analysis were needed to accurately measure aromatics down to 0.2% aromatic molecules.
More specifically, to accurately measure low levels of all molecules with at least one aromatic function by NMR, the standard D 5292-99 method was modified to give a minimum carbon sensitivity of 500:1 (by ASTM standard practice E 386), A 15-hour duration run on a 400-500 MHz NMR with a 10-12 mm Nalorac probe was used. Acorn PC integration software was used to define the shape of the baseline and consistently integrate. The carrier frequency was changed once during the run to avoid artifacts from imaging the aliphatic peak into the aromatic region. By taking spectra on either side of the carrier spectra, the resolution was improved significantly.
A wax sample composed of several different batches of hydrotreated Fischer-Tropsch wax, all made using a Co-based Fischer-Tropsch catalyst, was prepared. The different batches of wax composing the wax sample were analyzed and all found to have the properties as shown in Table II
The Co-based Fischer-Tropsch wax was hydroisomerized over a Pt/SAPO-11 catalyst with an alumina binder. Operating conditions included temperatures between 635° F. and 675° F. (335° C. and 358° C.), LHSV of 1.0 hr−1, reactor pressure of about 500 psig and once-through hydrogen rates of between 5 and 6 MSCF/bbl. The reactor effluent passed directly to a second reactor containing a Pd on silica-alumina hydrofinishing catalyst also operated at 500 psig. Conditions in the second reactor included a temperature of about 350° F. (177° C.) and an LHSV of 2.0 hr−1.
The products boiling above 650° F. were fractionated by vacuum distillation to produce distillate fractions of different viscosity grades. Three Fischer-Tropsch derived lubricant base oils were obtained. Two were distillate side-cut fractions (XLFTBO and XXLFT BOC) and one was a distillate bottoms fraction (HFTBO). Test data on the three Fischer-Tropsch derived lubricant base oils are shown in Table III, below.
HFTBO is an example of a pour point reducing blend component with a low traction coefficient. XLFTBO is an example of a fraction of a lubricating base oil having a Noack volatility less than a Noack Volatility Factor by Equation (1). XXLFTBO is an example of a fraction of a lubricating base oil having a Noack volatility less than a Noack Volatility Factor less than both a Noack Volatility Factor by Equation (1) and a Noack Volatility Factor by Equation (2).
Chevron MOTEX 2T-X is a two-cycle outboard engine oil formulated with high quality mineral base oil, polyisobutylene, a high performance low ash detergent/dispersant additive package, and a high flash solvent. Three different blends of two-cycle gasoline engine lubricant using the same high performance low ash detergent/dispersant additive package and polyisobutylene synthetic base oil used in Chevron Motex 2T-X were prepared (BlendB, BlendC, antd BlendF) using the Fischer-Tropsch derived base oils described earlier. A comparison blend (COMP BlendA) using conventional mineral base oil and high flash solvent was also prepared. The formulations of these blends are summarized in Table IV.
The performance properties of three of these two-cycle gasoline engine lubricant blends are shown in Table V.
Flash Points were measured by the Cleveland Open Cup Tester, using ASTM D92-05a. Aniline Points were measured by ASTM D611-04. BlendB, BlendC, and BlendF had essentially no hydrocarbon solvent having a maximum boiling point less than 250 degrees C., yet they all had low exhaust smoke index values, lower pour points, and improved miscibility compared to COMP BlendA made with conventional mineral oil base oil and high flash solvent. BlendF, comprising the highest level of HFTBO, gave an especially high lubricity index, yet still had excellent miscibility and a good exhaust smoke index.
A blend of two-cycle gasoline engine lubricant using a detergent/dispersant additive package designed to meet the specifications for Thailand Domestic (TIS 1040-2541 [1998]) was prepared using the Fischer-Tropsch derived base oils described earlier. A comparison blend using conventional petroleum-derived base oil and high flash solvent was also prepared. The formulations of these blends are summarized in Table VI
The performance properties of these two-cycle gasoline engine lubricant blends are shown in Table VII.
BlendE also comprised the pour point reducing blend component having a low traction coefficient, HFTBO. Note that this blend had had an especially low pour point and good low temperature fluidity at −25° C. BlendE had better low temperature fluidity, lower pour point, better gasoline miscibility, better detergency, and a better piston skirt deposit index than COMP BlendD made with conventional mineral oil base oil and greater than 5 wt % hydrocarbon solvent having a maximum boiling point less than 250 degrees C. BlendE, with the addition of less than 5 wt % hydrocarbon solvent having a maximum boiling point less than 250 degrees C., would easily pass the requirements of both JASO M345:2003 and ISO 13738:2000 (E), classifications C and D.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Furthermore, all ranges disclosed herein are inclusive of the endpoints and are independently combinable.
All of the publications, patents and patent applications cited in this application are herein incorporated by reference in their entirety to the same extent as if the disclosure of each individual publication, patent application or patent was specifically and individually indicated to be incorporated by reference in its entirety.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. Many modifications of the exemplary embodiments of the invention disclosed above will readily occur to those skilled in the art. Accordingly, the invention is to be construed as including all structure and methods that fall within the scope of the appended claims.
