Patent Application
20110154725
The invention relates to octane-boosting agents boosting for gasoline automotive fuels, more particularly, for alcoholated gasoline automotive fuels, and is suitable for improving the performance of the aforementioned types of automotive fuels.
Progress in the field of automobile motor design and the increasing stringency of requirements on the environmental characteristics of automotive fuels are responsible for the constantly increasing demand for high-octane gasolines providing toxicity levels of exhaust emissions in compliance with the contemporary standards. It is impossible to increase the proportion of production of high-octane gasolines unless antiknock additives are widely used to boost the knock resistance of gasoline fuels.
Currently used antiknocks are oxygenates, including a wide spectrum of oxygenated compounds. As a rule, these are mixtures with hardly controllable compositions containing alcohols, alkyl ethers and esters, carbonyl compounds, and reaction products thereof. Most of them are capable of converting to peroxides under the action of air oxygen, these peroxides reducing the chemical stability of the fuel and leading to piling up of carboxylic acids that cause corrosion of motors and fuel tanks. A serious disadvantage of methyl tert-butyl ether, which is widely used at present, consists of a noticeable toxicity and a low degradability, leading to the proliferation and accumulation of toxic products in the soil and water pools.
Cyclic ketals, which are prepared by reacting glycols with carbonyl compounds (1,3-dioxolanes), in fuel compositions are known to enhance the environmental characteristics of automobile motors. For example, they reduce the level of solid particulates and toxic incomplete combustion products in the exhaust emissions from diesel motors [see U.S. 2004025417, publ. Feb. 12, 2004; FR 2833607, publ. Jun. 20, 2003; AT 311428T, publ. Dec. 15, 2005; and JP 7331262, publ. Dec. 19, 1995] and improve the environmental characteristics of biodiesel [US 2006/199,970, publ. Sep. 7, 2006; WO 2006/084048, publ. Aug. 10, 2006] and gasoline [U.S. Pat. No. 4,390,345, publ. Jun. 28, 1983; WO 8903242, publ. Apr. 20, 1989].
The invention protected by patent CA 2530219, published Feb. 3, 2005, describes a method for preparing oxygenate and use thereof as an additive enhancing the ignition ability of gasoline and reducing the level of hazardous emissions to the atmosphere. Oxygenate is the product of reaction of glycerol with a carbonyl compound, e.g., acetone, alkylated with a tertiary olefin. The need for alkylation is due to insufficient solubilities of 1,3-dioxolanes, which have a free hydroxy group, in hydrocarbon fuels. This imposes a considerable limitation on use of glycerol 1,3-dioxolanes as gasoline additives.
The above-cited documents do not contain evidence of the antiknock activity of 1,3-dioxolanes in gasoline.
The alkylation of glycerol with isobutylene is described to prepare polyalkyl glycerol ethers for use as gasoline additives [see DE 4445635, publ. Jun. 27, 1996; EP 0718270, publ. Jun. 26, 1996]. If acetone is used as a solvent, the reaction mixture represents a mixture of tert-butyl glycerol ethers having various degrees of substitution and an admixture of free glycerol, and further contains a cyclic ketal (2,2-dimethyl-4-tert-butoxymethyl-1,3-dioxolane) and an admixture of 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane, which contains a free hydroxy group. These reaction mixtures were shown to perform as efficient octane booster additives when added to gasoline. The free hydroxy groups of glycerol are to be alkylated for the provision of phase tolerance, which is associated with additional labor and energy costs. Nonetheless, the occurrence of nonalkylated glycerol in the mixture, as well as admixtures of free glycerol and nonalkylated 4-hydroxymethyl-1,3-dioxolane, increase the probability of stratification of a gasoline composition including this additive. The complex and volatile constitution of the additive depending on the reaction parameters in a multicomponent system is responsible for the volatility and unpredictability of the antiknock properties thereof.
A multifunctional ethanol-based gasoline additive is known to ensure boosting of the octane number (ON), a reduction of the cloud point, and a decrease in emission toxicity level, this additive containing, along with ethanol, N-methylaniline, acetaldehyde, crotonic aldehyde, ethyl ether, and a multifunctional additive AVTOMAG [see RU 2148077, publ. Apr. 27, 2000].
An ethanol-based gasoline additive is known [see RU 2068871, C1, publ. Nov. 10, 1996], this additive containing, as a stabilizer, a cosolvent which represents wastes from the hydrolysis process of ethanol production from wood raw materials, so-called an aldehyde/ether/alcohol fraction, in an amount of 8 to 80% by weight. Addition of this additive to gasoline in an amount of 2 to 20% by weight boosts the octane number and affords an automotive fuel that does not stratify at reduced temperatures. The wastes from the hydrolysis process contained in the additive are mixtures of aliphatic alcohols C3-C5, methyl and ethyl esters of formic and acetic acids, furfural, and other organics.
A gasoline additive based on stabilized ethanol is also known, this additive containing N-methylaniline, ferrocene, and/or derivatives thereof, wherein the alcohol is stabilized using lower aliphatic alcohols, ethers, or the aldehyde/alcohol fraction obtained from the wastes of ethanol production from wood raw materials [see RU 2129141, publ. Apr. 20, 1999].
The problem to be solved by the subject invention is the creation of a universal agent for gasoline automotive fuel having a higher octane-boosting effect that would be easily derived from available products of chemical productions or from wastes or intermediates of carbohydrate raw materials processing.
Experiments were carried out to show that a combination of an alcohol with the product of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed or a mixture of the aforementioned products, is more efficient to boost the octane number of gasoline than each of the aforementioned components individually, thereby causing a synergistic effect.
In addition, the problem of phase intolerance with gasoline fuel is eliminated, this problem arising from the existence of a free hydroxy group in the products of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed.
Thus, the aforementioned problem is solved by that, as the octane-boosting agent for gasoline automotive fuel, the invention uses a combination of an alcohol and the product of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed, or mixtures of the products.
Preferred compounds containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed are saccharides or dihydric, trihydric, and polyhydric alcohols.
Preferably, the aforementioned saccharides represent monosaccharides; however oligosaccharides are useful, too, being converted to monosaccharides in the course of the reaction with carbonyl compounds.
Useful monosaccharides are pentoses or hexoses and mixtures thereof, which can be obtained by mixing individual monosaccharides or by the conversion of carbohydrate raw materials.
The preferred pentose is xylose or arabinose; the preferred hexose is glucose.
Useful dihydric alcohols are glycols, for example, ethylene glycol; useful trihydric alcohol is glycerol; and useful polyhydric alcohols are erythritols, for example, pentaerythritol.
Useful carbonyl compounds are compounds represented by lower aldehydes or lower ketones, for example, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, diethyl ketone, and cyclohexanone.
Useful alcohols are aliphatic alcohols containing up to five carbon atoms, preferably ethanol.
In the context of the subject invention, a gasoline automotive fuel means gasoline or an alcohol/gasoline composition.
The fact that the claimed octane-boosting agent for gasoline automotive fuel contains an alcohol in combination with the products of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed or mixtures of these products, is essential for providing a high octane-boosting effect. Alcohols as such are insufficiently efficient antiknocks; further, [U.S. Pat. No. 4,541,836, publ. Sep. 17, 1985] teaches that addition of anhydrous ethanol to gasoline in an amount of up to 10% boosts the octane number of the fuel by 2 to 4 units.
The study of the octane-boosting effect of cyclic monosaccharide ketals, exemplifying a product of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed, this study having been carried out on a standard hydrocarbon model mixture, showed that pure ketals formed by monosaccharides and acetone practically do not boost the octane number of hydrocarbons. For example, addition of acetone arabinose ketal to the isooctane/n-heptane model mixture (4:1) in an amount of about 8% by weight practically does not affect the octane number thereof. A similar pattern holds for ketals of trihydric alcohols: when gasoline contains 10% acetone ethylene glycol ketal, the boost of the octane number is 1.4 units; for methyl ethyl ketone glycerol ketal, the boost is 0.9 units; and for other ketals, the boost of the octane number falls within the measurement error.
Addition of ethanol to the system gives a boost to the octane number of the model mixture: by 10.4 units for arabinose acetone ketal (the weight ratio ketal:ethanol=0.75:1.0), by 13.1 units for xylose/acetone ketal (the weight ratio ketal:ethanol=0.75:1.0), and by 12.6 units for glycerol/acetone ketal (the weight ratio ketal:ethanol=1.0:1.0). This boost signifies a synergistic effect of the alcohol/cyclic ketal pair, this effect providing the high octane-boosting effect of the claimed agents.
It is important that the order in which combined are an alcohol and the product of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed, does not influence the octane-boosting effect of the claimed agent. The only essential factor is the combination of the specified components, regardless of whether they were compounded before being added to an automotive gasoline fuel or compounding occurred in the automotive gasoline fuel itself. In this context, the agent has the octane-boosting effect both in gasoline and alcoholated gasoline compositions.
The alcohol contained in the additive removes the problem of phase tolerance with gasoline for cyclic ketals and acetals having free hydroxy groups. In the presence of an alcohol, these compounds form a single-phase stable system with gasoline, regardless of the nature of their alkyl substituents.
Cyclic glycerol ketals are known to enhance the phase stability of alcoholated gasoline [see GB 811406, publ. Apr. 2, 1959; U.S. Pat. No. 4,390,344, publ. Jun. 28, 1983]. This fully holds for cyclic monosaccharide ketals. For example, addition of cyclic monosaccharide ketals or mixtures of cyclic monosaccharide ketals in an amount of 3 to 8 wt % by weight to a two-phase system containing gasoline and 10% by volume of aqueous ethanol, affords a homogeneous system. Thus, the aforementioned ketals stabilize the phase homogeneity of gasoline, increasing the threshold water concentration beyond which water is segregated to an autonomous phase. Therefore, not only dry ethanol but also rectified spirit containing 3.6% water and aqueous alcohol containing up to 5% water, become useful for compounding a hydrocarbon and an alcohol.
The product of reaction of a carbonyl compound with a compound containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed (this product is necessary for carrying out the invention) can be prepared in the following way.
One group of compounds containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed, are saccharides.
Useful saccharides are individual monosaccharides and mixtures thereof, for example, a pentose fraction obtained from vegetable raw materials as described below.
As sources of mixed saccharides for manufacturing products for use in the subject agent, it is expedient to use low-cost agricultural residues that have no food and feed value, for example, cereal straw and other wastes of grain processing used for manufacturing bioethanol.
The raw material is subjected to pre-treatment including grinding to particle sizes of 2.0 to 0.5 mm, the chemical separation of associated components (waxes, fats, terpenes, soluble pectins, proteins, lignins, and inorganic compounds) by means of extraction with ethanol/benzene mixtures followed by acid hydrolysis, and the separation of the hydrocarbon fraction using prior-art procedures [see Yu. I. Khol'kin, “The Technology of Hydrolysis Production Processes,” Moscow: Lesnaya Promyshlennost, 1989]. As a result, monosaccharide mixtures are obtained in a amount of 20 to 30% by weight based on the raw material which represent a so-called “pentose fraction”, which contains mainly xylose and arabinose with a glucose admixture.
Table 1 shows the constitution of the products of pre-treatment and hydrolysis of various raw materials.
The products are obtained by reacting these materials with carbonyl compounds under acid catalysis conditions with newly formed water being removed by means of one of the known methods [see “Methods in Carbohydrate Chemistry,” Ed. by R. Whilstler and M. Wolfrom, New York: Academic Press, 1962-1965; Russian translation: “Metody Khimii Uglevodov,” Ed by N. K. Kochetkov, Moscow: Mir, 1967, p. 165]. For separating byproducts which are poorly soluble in hydrocarbons, the reaction mixture is extracted by benzene or another suitable solvent; the extract is concentrated and then used in the octane-boosting agent. Useful also are di- and oligosaccharides, which hydrolyze during the reaction with carbonyl compounds and also yield mixtures of appropriate products.
Useful carbonyl compounds are lower aldehydes or ketones; for the former, the reaction represents an acetalization reaction and the reaction products represent cyclic acetals; for the latter, the reaction represents a ketalization reaction and the reaction products represent cyclic ketals.
Inasmuch as the aforementioned monosaccharides each contain at least two pairs of hydroxy groups capable of forming cycles in reaction with carbonyl compounds, derivatives can be obtained each containing either one or two cyclic groups per monosaccharide molecule. To reach the maximal octane-boosting effect, the reaction is carried out in the presence of an excess of a carbonyl compound, thereby ensuring the maximal extent of conversion to products each containing two oxygenated cycles. Table 2 exemplifies physicochemical characteristics of the products of reaction of saccharides (individual monosaccharides, disaccharides, or monosaccharide mixtures) with acetone.
The monosaccharide acetone cyclic diketals listed in Table 2 represent solid products at room temperature or viscous liquid products soluble in alcohol; their mixtures with alcohol are soluble in gasoline.
When the pentose fraction isolated from the hydrolyzate of carbohydrate raw material is used, the yield of a cyclic diketal mixture is 57 to 70% depending on the raw material used to obtain the pentose fraction. Dry stalks of miscanthus grass are a promising raw material for the subject additives, as they are the richest in pentoses and provide the highest yield of the cyclic diketal mixture. Table 3 gives the weight constitution of the mixture obtained by the acetone ketalization of the pentose fraction isolated from dry stalks of miscanthus grass.
The ketalization products of monosaccharides are nontoxic. Laboratory experiments on SHK line mice (from Stolbovaya nursery) showed that samples of arabinose and glucose cyclic diketals in olive oil administered to animals per os in doses of from 100 to 6000 mg/kg, when observed over 30 days, are well tolerated in animals and do not cause any change in their condition.
Cyclic diketals of monosaccharides are stable in the composition of the octane-boosting agent; with this, they are capable of hydrolytic splitting to yield nontoxic products, thereby having an essential advantage over toxic and undegradable alkyl ethers, specifically, methyl tert-butyl ether, which is widely used in oxygenates.
Another group of compounds containing at least two hydroxy groups that allow cycles with carbonyl compounds to be formed consists of di-, tri-, and polyhydric alcohols.
The products of reaction of di-, tri-, and polyhydric alcohols with carbonyl compounds, namely cyclic acetals and ketals, are prepared in one-step synthesis from available large-scale products (glycerol, ethylene glycol, pentaerythritol, paraform, acetaldehyde, acetone, and others) using known methods under acid catalysis conditions with the azeotropic (entrainment) distillation of reaction water [see A. Ternay, Contemporary Organic Chemistry, Philadelphia: Sounders, 1979; Russian translation: A. Terney, Sovremennye Metody Organicheskoi Khimii, vol. 2, Moscow: Mir, 1981, p. 20]. Where the azeotropic distillation of reaction water is carried out in the presence of methyl ethyl ketone, the reaction product represents a mixture of the relevant cyclic compounds, this mixture also being useful in the composition of the subject octane-boosting agent.
Cyclic acetals and ketals of di- and triatomic alcohols are liquids which are well soluble in alcohols; their mixtures with an alcohol are well soluble in gasoline.
One more example of a cyclic acetal useful in the claimed octane boosting agent is pentaerythritol diformal, which is the product of reaction of pentaerythritol with formaldehyde. Pentaerythritol is an available large-scale product of chemical industry and represents a polyhydric alcohol having a branched structure and containing four hydroxy groups which pairwise interact with formaldehyde to yield two dioxane cycles. Diformal pentaerythritol formal is an alcohol-soluble solid.
The octane-boosting effect of the subject agents has been studied on n-heptane and (1:1) and (4:1) isooctane/n-heptane model mixtures. Measurements are carried out by a standard method under the Russian State Standard (GOST) 8226-82 “Motor Fuels. A Research Method for Determination of Octane Number” (Method 1) and by a proximate method (Method 2), whose results are proximate to standard methods. The proximate method uses an Oktanometr OK-2m (PLUS RADIO) gasoline antiknock value meter, this meter being suitable for the proximate determination of gasoline octane numbers in monitoring gasoline production processes, in research work, and in consumer acceptance of gasolines. The operating principle of Oktanometr OK-2m is the measurement of reaction parameters of the cool-flame oxidation of gasolines followed by using them to determine the antiknock value as equivalent to the motor and research octane numbers. The references used are the reaction parameters of cool-flame oxidation of reference fuels manufactured according to GOST 511-82.
Tables 4 and 5 give examples to illustrate the octane-boosting effect of agents containing various individual cyclic ketals and acetals and various aliphatic alcohols on n-heptane and isooctane/n-heptane model mixtures.
. %
The data of Tables 4 and 5 support the well-known fact that the lower the octane number of the initial hydrocarbon mixture, the greater the effect caused by the octane-boosting agent. The octane-boost effect over the range of the concentrations studied is roughly proportional to the weight percentage of the agent in the mixture. Further, these data show that the synergistic octane-boosting effect of cyclic ketals and acetals is manifested in the presence of alcohols of various structures.
Table 6 shows the octane-boosting effects of ethanol-containing agents in combination with mixtures of cyclic ketals of various structures.
For a number of octane-boosting agents, tests were carried out on automotive gasoline and straight-run gasoline.
Table 7 gives examples to illustrate the octane-boosting effect of the monosaccharide-based subject agents on automotive gasoline.
Table 8 displays the results of tests of several fuel composition variants including the straight-run gasoline fraction and octane-boosting agents containing glycerol and ethylene glycol cyclic ketals and ethanol.
If the automotive gasoline fuel used is a ready-for-use alcohol-gasoline composition (AGC), then cyclic ketal or a mixture of cyclic ketals is added in the required amount directly to the alcohol-gasoline composition.
The data contained in Tables 9 and 10 demonstrate the effect of cyclic ketals on the octane characteristics of AGCs
The phase stability of alcohol/gasoline compositions which is quantitatively characterized by the stratification temperature, is measured according to the Russian State Standard (GOST) 5066-91 using a KRIO VT low-temperature thermostat (manufactured by TERMEX-II). The data of Table 11 demonstrate the effect of glycerol ethylene glycol cyclic ketals on the phase stability of alcohol/gasoline compositions at reduced temperatures.
Thus, the above results demonstrate that the subject agents have a well-defined octane-boosting and stabilizing effects on alcoholated gasoline fuels.
Experiments on model systems showed that the octane-boosting agents of the invention have a low tendency to gumming. For example, while the Russian State Standards allow existent gums contents of up to 6.0 mg per 100 cm fuel, the actual gumming of the agent containing 10% cyclic acetone glycerol ketal was 0.6 mg per 100 cm fuel, and for the 30% content, 3.0 mg per 100 cm. In light of the known influence of the aforementioned agents on the reduction of the level of hazardous products in exhaust emissions, it may be stated that these agents will have a complex positive effect on the performance of the engine.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008121078 | Mar 2008 | RU | national |
| 2008121080 | Mar 2008 | RU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/RU2009/000266 | 5/27/2009 | WO | 00 | 2/16/2011 |
