Patent Application
20060196107
The present teachings relate to fuel additives useful for reducing and/or preventing the formation of intake valve deposits.
Fuels used in internal combustion engines generally contain components that lead to the formation of undesirable engine deposits. It is believed that these deposits can negatively affect engine performance by, for example, clogging fuel induction systems. Considerable research has been devoted to additives for controlling (preventing and/or reducing) deposit formation in internal combustion engines. The preparation and identification of fuel additives capable of controlling undesirable deposit formation has been a focal point of this research.
Compositions comprising Mannich products have previously been used as fuel additives for controlling deposit formation in internal combustion engines. Mannich products may be obtained by reacting an aldehyde, an amine, and a hydroxyl aromatic compound. These products may be combined with other ingredients to form detergent compositions. Despite extensive prior research activities on Mannich fuel additives, a need exists for Mannich products having superior performance capabilities, particularly with regard to controlling deposit formation in currently available hotter-burning engines. The present disclosure addresses a solution to such a need.
According to one aspect of the disclosure, there is provided a compound of formula (I):
wherein R1 R3, R4, and R5 may each be independently chosen from H and substituted and unsubstituted hydrocarbyl radicals, wherein the substituents are chosen from halogen, hydroxyl, alkyl, alkenyl, alkynyl, nitro, and amino radicals, R2 may be chosen from substituted and unsubstituted hydrocarbyl radicals having a number average molecular weight ranging from about 500 to about 3000, wherein the substituents are chosen from halogen, hydroxyl, alkyl, alkenyl, alkynyl, nitro, and amino radicals, and R6 and R7 may be each independently chosen from H and C1-C5 hydrocarbyl radicals; a process for preparing a compound of formula (I) comprising reacting a compound of formula (II):
with (A) a formaldehyde source, (B) optionally a ketone, and (C) a primary amine to yield the compound of formula (I); and a fuel additive composition comprising a cyclic Mannich product prepared by the reaction of (A) a substituted hydroxyaromatic compound having at least one unsubstituted position ortho to the hydroxy group, (B) a formaldehyde source, and (C) a primary amine.
It is to be understood that both the foregoing general description and the following description of various embodiments are exemplary and explanatory only and are not restrictive.
The disclosed fuel additive comprises, in one embodiment, a detergent, such as a cyclic Mannich product of formula (I):
wherein R1-R7 are as defined above. The cyclic Mannich product may be prepared by the reaction of (A) a substituted hydroxyaromatic compound having at least one unsubstituted position ortho to the hydroxy group, (B) a formaldehyde source, (C) optionally a ketone, and (D) a primary amine.
Any substituted hydroxyaromatic compound may be used provided it reacts with the formaldehyde source and the primary amine. In accordance with the present disclosure, the hydroxyaromatic compound may be substituted with at least one substituent other than the hydroxyl moiety. For example, the at least one substituent may be chosen from hydrocarbyl radicals, for example alkyl and alkenyl radicals, such as C1-C4 alkyl and alkenyl radicals. Representative examples of hydroxyaromatic compounds useful in the process disclosed herein include, but are not limited to, phenolic compounds, including alkyl-substituted phenols. Phenolic compounds that may be used include, but are not limited to, high molecular weight alkyl-substituted derivatives of resorcinol, hydroquinone, cresol, catechol, xylenol, hydroxydiphenyl, benzylphenol, phenethylphenol, naphthol, and tolylnaphthol, among others, all of which may be optionally further substituted with any other substituent. Additional substituents may be chosen from, for example, halogen, hydroxyl, alkyl, alkenyl, alkynyl, nitro, and amino radicals. Additional non-limiting examples of suitable oxyaromatic compounds include 4-octylphenol, 4-heptylphenol, 4-nonylphenol, and 4-dodecylphenol.
Mention may also be made of polypropylphenol (formed by alkylating phenol with polypropylene), polybutylphenols (formed by alkylating phenol with polybutenes and/or polyisobutylene), and polybutyl-co-polypropylphenols (formed by alkylating phenol with a copolymer of butylene and/or butylene and propylene). Other similar long-chain alkylphenols may also be used. Non-limiting examples include phenols alkylated with copolymers of butylene and/or isobutylene and/or propylene, and at least one mono-olefinic comonomers copolymerizable therewith (e.g., ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, etc.) where the copolymer molecule may comprise at least 50% by weight of butylene and/or isobutylene and/or propylene units. Such compounds may be further substituted with at least one additional group, e.g., hydrocarbyl groups, for example C1-C4 alkyl groups, such as methyl. According to one aspect of the present disclosure, a suitable hydroxyaromatic compound may be polyisobutylcresol. The comonomers polymerized with propylene or the butylenes may be aliphatic and can also comprise non-aliphatic groups, e.g., styrene, o-methylstyrene, p-methylstyrene, divinyl benzene, and the like. Thus, in any case the resulting polymers and copolymers used in forming the alkyl-substituted hydroxyaromatic compounds may be substantially aliphatic hydrocarbon polymers.
Polybutylphenol (formed by alkylating phenol with polybutylene) may be suitable for the purposes of the present disclosure. The polybutylphenol ring may be further substituted with, for example, alkyl groups, such as lower, e.g., C1-C4, alkyl groups, for example methyl, in addition to other groups such as, for example, halogen, hydroxyl, alkyl, alkenyl, alkynyl, nitro, and amino radicals.
According to one aspect of the present disclosure, the polybutylphenol may be polyisobutylcresol. Unless otherwise specified herein, the term “polybutylene” is used in a generic sense to include polymers made from “pure” or “substantially pure” 1-butene or isobutene, and polymers made from mixtures of two or all three of 1-butene, 2-butene and isobutene. Commercial grades of such polymers may also comprise insignificant amounts of other olefins. So-called high reactivity polybutylenes having relatively high proportions of polymer molecules having a terminal vinylidene group, formed by methods such as described, for example, in U.S. Pat. No. 4,152,499, and W. German Offenlegungsschrift 29 04 31 the disclosures of which are incorporated by reference herein), may also be suitable for use in forming the long chain alkylated phenol reactant.
The alkylation of the hydroxyaromatic compound may be performed in the presence of an alkylating catalyst at a temperature ranging from about 50 to about 200° C. Acidic catalysts may generally be used to promote Friedel-Crafts alkylation. Typical catalysts used in commercial production include, but are not limited to, sulfuric acid, BF3, aluminum phenoxide, methane-sulfonic acid, cationic exchange resin, acidic clays and modified zeolites or other Lewis acids, such as tin halides.
The long chain alkyl substituents on the benzene ring of the phenolic compound may be derived from polyolefins having a number average molecular weight of from about 500 to about 3000 (for example, from about 500 to about 2000) as determined by gel permeation chromatography (GPC). The polyolefin may also have a polydispersity (weight average molecular weight/number average molecular weight) in the range of about 1 to about 4, for example from about 1 to about 2, as determined by GPC.
According to certain aspects of the present disclosure, polyalkylphenol reactants, e.g., polypropylphenol and polybutylphenol whose alkyl groups have a number average molecular weight of from about 650 to about 1200 may be suitable for the preparation of the cyclic Mannich product. According to certain embodiments, an alkyl group useful in accordance with the present disclosure may be a polybutyl group derived from polybutylene having a number average molecular weight in the range of from about 650 to about 950.
According to various embodiments, the hydroxyaromatic compound is chosen from compounds of formula (II):
wherein R1-R4 may be as defined above.
The formaldehyde source useful for the purposes of the present disclosure may include any source capable of providing formaldehyde to participate in the Mannich reaction. Suitable non-limiting examples of formaldehyde sources include formaldehyde, paraformaldehyde, and aqueous formaldehyde solutions, such as formalin. The formaldehyde may be inhibited or uninhibited, and may be in solution, for example aqueous or aqueous-alcoholic solution.
According to certain aspects of the disclosure, the aqueous-alcoholic solutions may be aqueous methanolic or ethanolic formaldehyde solutions, wherein the formaldehyde may be present as a 5 to 80% aqueous solution, containing 0.5 to 60% aqueous alcohol solution. Non-limiting examples of such solutions include 37% aqueous formaldehyde containing 1.5% methanol, 37% aqueous formaldehyde containing 15% methanol, 44% aqueous formaldehyde containing 7% methanol, and 44% aqueous formaldehyde containing 1% methanol.
The ketones useful for the purposes of the present disclosure include those chosen from formula (III):
wherein R6 and R7 are as defined above for formula (I).
The amines useful for the purposes of the present disclosure may include molecules having at least one suitable reactive primary amine moiety that may react with an aldehyde or ketone and a substituted hydroxyaromatic compound to form a cyclic Mannich product. The amines may be further substituted by other groups, for example hydrocarbyl, hydroxyl, cyano, amido, and halogen. By way of non-limiting example the amines may be chosen from aliphatic amines containing from about 1 to about 20 carbon atoms such as methylamine, ethylamine, n-propylamine, n-butylamine, isobutylamine, sec-butylamine, n-hexylamine, 2-ethylhexylamine, laurylamine, oleylamine, stearylamine, and eicosylamine. Another suitable class of amines for the purposes of the present disclosure may include polyamines, such as polyalkylenepolyamines, for example polyethylenepolyamines. They may be represented by the following formula:
H2N—(CH2CH2NH)x—H
wherein x may be an integer ranging from about 1 to about 6. The amines may be used individually, or as a mixture. Suitable non-limiting examples of polyethylene polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. Corresponding polypropylene polyamines may also be suitable reactants. The alkylene polyamines may be obtained from the reaction of ammonia and dihaloalkanes, such as dichloroalkanes. According to one aspect of the disclosure, a suitable polyamine is N,N-dimethyl-1,3-propane diamine.
The substituted hydroxyaromatic compound, the formaldehyde source or ketone, and the primary amine may be reacted under suitable Mannich reaction conditions to form a cyclic Mannich product. The reaction may be conducted at a temperature in the range of 40° to 200° C. The reaction may be conducted in bulk (no diluent or solvent) or in a solvent or diluent. Water may be evolved and can be removed by azeotropic distillation during the course of the reaction. In the case where R6 and R7 are hydrogen (formulae (I)), the cyclic Mannich product may be formed, in one embodiment, by reacting the substituted hydroxyaromatic compound, the formaldehyde source, and the amine in the molar ratio of 1.0:0.2-2.8:1.0, respectively, for example 1:0.5-2.5:1.5-2.5, for example 1:2:1. In the instances where R6 and R7 are other than hydrogen, the reaction may be performed in two steps. First, one mole of formaldehyde is reacted per mole of amine. Second, one mole of ketone (formula (III)) is reacted per mole of amine.
The cyclic Mannich product may be present in a fuel additive composition in any amount sufficient to reduce and/or prevent the formation of deposits on intake valves. In an embodiment, the cyclic Mannich product may comprise from about 5 ptb to about 300 ptb, for example from about 25 ptb to about 200 ptb, and as a further example from about 75 to about 150 ptb, of active material in the fuel additive composition. Commercial examples of a fuel additive comprising a Mannich product include HiTEC® 6416 (Ethyl Corp., Richmond, Va.).
The disclosed fuel additive composition may comprise reaction by-products. For example, the fuel additive composition may, in one embodiment, comprise up to 15% by weight of unreacted polyisobutylene phenol, and/or up to 10% by weight of unreacted polyisobutylene.
When formulating the fuel compositions in accordance with the present disclosure, the cyclic Mannich product (with or without other additives) is employed in an amount sufficient to reduce or inhibit deposit formation in an internal combustion engine. Thus, the fuels may contain a minor amount of the cyclic Mannich product that prevents or reduces formation of engine deposits, including intake system deposits, for example intake valve deposits in spark-ignition internal combustion engines. By way of non-limiting example, the fuels in accordance with the present disclosure may contain, on an active ingredient basis, an amount of cyclic Mannich product in the range of about 5 to about 2000 ptb (pounds by weight of additive per thousand barrels by volume of fuel), for example an amount ranging from about 5 to about 50 ptb, for example an amount ranging from about 15 to about 40 ptb.
Fuel compositions may comprise a major amount of a base fuel and a minor amount of a fuel additive composition. A “major amount” may be understood to mean greater than or equal to about 50%. A “minor amount” may be understood to mean less than about 50%.
The fuel compositions of the present disclosure may contain at least one supplemental additive in addition to the cyclic Mannich product. The at least one supplemental additive may be chosen from, for example, dispersants, detergents, antioxidants, carrier fluids, metal deactivators, dyes, markers, corrosion inhibitors, biocides, antistatic additives, drag-reducing agents, demulsifiers, dehazers, anti-icing additives, anti-knock additives, anti-valve-seat recession additives, lubricity additives, friction modifiers, multifunctional additives (e.g., methylcyclopentadienyl manganese tricarbonyl, MMT®, Afton Chemical Corp., Richmond, Va. and/or other cyclopentadienyl compounds), and combustion improvers. The at least one supplemental additive may be provided in the fuel composition in an amount necessary to achieve the desired effect.
The base fuels used in formulating the fuel compositions according to the present disclosure include any base fuels suitable for use in the operation of spark-ignition internal combustion engines, such as leaded or unleaded motor and aviation gasolines, and so-called reformulated gasolines which typically contain both hydrocarbons of the gasoline boiling range and fuel-soluble oxygenated blending agents, such as alcohols, ethers and other suitable oxygen-containing organic compounds. Suitable oxygenates include, for example, methanol, ethanol, isopropanol, t-butanol, mixed C1 to C5 alcohols, methyl tertiary butyl ether, tertiary amyl methyl ether, ethyl tertiary butyl ether and mixed ethers. Oxygenates, when used, will normally be present in the base fuel in an amount below about 25% by volume, for example in an amount that provides an oxygen content in the overall fuel in the range of about 0.5 to about 5 percent by volume.
According to one aspect of the present disclosure, the cyclic Mannich products are used in combination with at least one liquid carrier or induction aid. Such carriers can be of various types such as, for example, liquid poly-α-olefin oligomers, mineral oils, liquid poly(oxyalkylene) compounds, liquid alcohols or polyols, polyalkenes, liquid esters, and similar liquid carriers. Mixtures of two or more such carriers can be employed.
Exemplary liquid carriers include 1) a mineral oil or a blend of mineral oils that have a viscosity index of less than about 120, 2) at least one poly-α-olefin oligomers, 3) at least one poly(oxyalkylene) compounds having an average molecular weight in the range of about 500 to about 3000, 4) polyalkenes or 5) a mixture of any two, three or all four of 1), 2), 3) and 4). The mineral oil carriers that can be used include paraffinic, naphthenic and asphaltic oils, and can be derived from various petroleum crude oils and processed in any suitable manner. For example, the mineral oils may be solvent extracted or hydrotreated oils. Reclaimed mineral oils can also be used. In accordance with certain aspects of the present disclosure, the mineral oil used has a viscosity at 40° C. of less than about 1600 SUS, for example ranging from about 300 to 1500 SUS at 40° C. Paraffinic mineral oils suitably have viscosities at 40° C. in the range of about 475 SUS to about 700 SUS. According to certain aspects of the present disclosure, the mineral oil has a viscosity index of less than about 100, for example less than about 70, such as in the range of from about 30 to about 60.
In some cases, the cyclic Mannich product can be synthesized in the carrier fluid. In other instances, the preformed detergent may be blended with a suitable amount of the carrier fluid. If desired, the detergent can be formed in a suitable carrier fluid and then blended with an additional quantity of the same or a different carrier fluid.
The additives used in formulating the fuels disclosed herein can be blended into the base fuel individually or in various sub-combinations. However, it may be desirable in some instances to blend all of the components concurrently using an additive concentrate (i.e., additives plus a diluent, such as a hydrocarbon solvent). The use of an additive concentrate takes advantage of the mutual compatibility afforded by the combination of ingredients when in the form of an additive concentrate. Also, use of a concentrate may reduce blending time and may lessen the possibility of blending errors.
Other aspects of the present invention include methods for reducing the formation or persistence of intake valve deposits and eliminating valve sticking in a spark-ignition engine by fueling and/or operating the engine with the fuel composition disclosed herein.
The ability of the following cyclic Mannich product (hereafter the “inventive compound”):
to reduce and/or prevent the formation of intake valve deposits was analyzed in a 5,000 mile test on a dynamometer in the 3.3 L, V-6 engine of a 1997 Dodge Intrepid. The inventive compound was combined with gasoline at 55.2 ptb in a dispersant/carrier comprising HiTEC® 6140 @ 17.11/14.2, with a total solids of 32. The average speed of the vehicle was 45.7 mph, and the cycle length was 76 miles. At the conclusion of 5,000 miles, the mass of the deposits on each of the six valves was measured. The results are provided in Table 1.
Next, the same test was performed a number of times using various additives, dispersant, carrier fluid, and fuel combinations. The comparative additives are known standards containing polyisobutenyl radicals, and the inventive product contains a highly reactive terminal vinylidene polyisobutenyl radical. The results are summarized in Table 2.
1Intake valve deposits
2Cylinder head deposits
3Piston top deposits
4HiTEC ® 6476.
The results summarized in Table 2 show that the inventive product actively reduced the formation of intake, cylinder head, and piston top deposits.
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.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a range of “less than 10” includes any and all subranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all subranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to “a friction modifier” includes two or more friction modifiers. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
It will be apparent to those skilled in the art that various modifications and variations can be made to various embodiments described herein without departing from the spirit or scope of the present teachings. Thus, it is intended that the various embodiments described herein cover other modifications and variations within the scope of the appended claims and their equivalents.
