BRPI0803522B1 - COMPOSITIONS OF DIESEL CYCLE FUEL CONTAINING DIANIDROHEXITOLES AND DERIVATIVES - Google Patents

Description

DIESEL CYCLE FUEL COMPOSITIONS CONTAINING DIANIDROHEXITOLS AND DERIVATIVES FIELD OF THE INVENTION

The present invention belongs to the field of diesel cycle engine fuel (compression ignition) compositions. More specifically, the invention relates to fuel compositions for use in diesel engine engines based on oxygenated compounds derived from dianhydrohexitols, mainly isosorbide and derivatives. Dianhydrohexitols are products of the double dehydration of hexitols (6-carbon sugar alcohols) and can be obtained from renewable sources such as cellulose and sucrose. Dianhydrohexitols and derivatives may be used as a cetane improver additive, as a hydrocarbon substitute and in combination with other oxygenates. BACKGROUND OF THE INVENTION

Prior to the development of low-cost oil exploration, renewable sources of energy were used. In fact, during the development of the compression ignition engine (US 542,846 and US 608,845) by Rudolph Diesel vegetable oils were used, according to the article by Shay, EG “Diesel fuel from vegetable oils: Status and opportunities.” Biomass and Bioenergy (1993) vol. 4 (4) pp. 227-242. Concern about the emission of greenhouse gases in the burning of fossil fuels makes the use of sustainable sources more relevant. Biofuels derived from plant biomass, such as ethanol, are currently the only sustainable source of liquid fuel. The most commonly used biofuel is ethanol, which is the product of the fermentation of dilute sucrose or glucose solutions according to the reaction (for glucose): C6H1206 -► 2 CH3CH2OH + 2 CO2 However, of every 6 carbons in the glucose molecule, only 4 will result in fuel. There is also a need for energy for ethanol distillation: even under optimal conditions, burning most of the sugarcane bagasse is needed, see Ensinas, A.V. et al. Analysis of process steam demand reduction and electricity generation in sugar and ethanol production from sugarcane. Energy Conversion and Management (2007) vol. 48 (11) pp. 2978-2987.

Glucose can also be obtained by acidic or enzymatic hydrolysis of cellulose, according to the article by Huber, G.W. et al .. Synthesis of transportation fuels from biomass: Chemistry, catalysts, and engineering. Chemical Reviews (2006) vol. 106 (9) pp. 4044-4098. Cellulose is the most common organic polymer, the main constituent of biomass. With an annual output of about 1.5 x 1012 tonnes it is considered a virtually inexhaustible raw material, see Klemm, D. et al., Cellulose: Fascinating Biopolymer and Sustainable Raw Material. Angewandte Chemie International Edition (2005) vol. 44 (22) pp. 3358-3393.

In addition to ethanol production by cellulose hydrolysis, other routes for converting biomass to fuels are also known. Rapid pyrolysis for bio-oil production and synthesis gas production can be cited for its use for fuel production. Gasification processes have the disadvantage of the low thermal efficiency of the process (maximum 16% to 50% of the energy recovered as fuel after synthesis), as cited above in the article by Huber, GW et al, 2006. Rapid pyrolysis is difficult to use as a fuel, requiring further refining, even according to the same article by Huber, GW et al., 2006. Ethanol, successfully used in Otto cycle engines (gasoline), cannot be used directly in engines. due to the low cetane number. However mixtures of diesel (hydrocarbons) and ethanol can be used successfully as long as solubilizing additives (surfactants and co-solvents) are used, see in this regard the articles by Ribeiro, Núbia M. et al. The role of additives for diesel and diesel blended fuels: A review. Energy Fuels (2007) vol. 21 (4) pp. 2433 and Hansen, A.C. et al. Ethanol-diesel fuel blends - A review. Bioresource Technology (2005) vol. 96 (3) pp. 277-285. In practice, the use of ethanol is limited to 20 vol%.

Vegetable oil derivatives can be used in diesel cycle engines, mainly biodiesel, ethyl and methyl esters of fatty acids, according to Ma, F. et al., Biodiesel production: A review. Bioresource Technology (1999) vol. 70 (1) pp. 1-15. However, the availability of vegetable oils is small compared to the availability of cellulose. Burning oxygen-containing fuels such as ethanol, biodiesel and others in diesel engine engines has the advantage of reducing soot emission, see articles by Curran, H.J. et al. Detailed Chemical Kinetic Modeling of Diesel Combustion with Oxygenated Fuels. Conference: 28th International Symposium on Combustion (2000); Westbrook, C.K. et al. The effect of molecular oxygen structure on soot production in direct-injection diesel engines. SANDIA REPORT SANO 2003-8207 (2003); and Pepiot-Desjardins, Perrine et al. Structural group analysis for soot reduction trend of oxygenated fuels. Combustion and Flame (2008) vol. 154 (1-2) pp. 191-205.

Another important parameter in fuels used in diesel engines is the ignition capacity after compression, expressed as cetane number, obtained on engine, ASTM D613 test or on equipment such as the IQT - Ignition Quality Test, ASTM D6890, see Murphy, M et al. Compendium of Experimental Cetane Number Data. National Renewable Energy Laboratory (2004). US 2,575,543 cites the use of diethyl ether (DEE), which can be obtained from renewable sources (ethanol) in diesel cycle engines, as a starting fuel. Mixtures of 15% to 50% DEE in the fuel could be used. The disadvantage of EED is its low boiling point (34.6 ° C) and density (0.7134 g / cm3), despite the high cetane number (140 - 160 reported in the literature, see above quotation by Murphy, M. et al (2004) US Patent 4,425,136 cites the direct use of carbohydrates in furnaces in the form of water, ethanol and sucrose solutions or other soluble sugar Water and ethanol are required respectively for solubilization. 5 to 12 carbon sugars are exemplified, including glucose The disadvantage is that sugars tend to caramelize and deposit in engines even at the higher combustion temperatures required by the invention ( The patent further teaches that the invention could be used in blends with diesel oil if engine modifications are made US Patent 4,891,049 teaches the use of carbonates as a diesel cycle engine fuel additive. fuels with up to 50% by weight of carbonate such as dimethyl carbonate (DMC) are claimed. Although it can be obtained from regenerable sources, the DMC cetane number is low, and use as gasoline is preferable, see Pacheco, M.A. et al. Review of Dimethyl Carbonate (DMC) Manufacturing and Its Characteristics as a Fuel Additive. Energy & Fuels (1997). US 5,308,365 teaches the use of glycerol diethers or triethers as an additive to diesel cycle engines in amounts of up to 30 vol% in the fuel. Decrease in soot content was observed. Glycerol can be considered a renewable material, being a byproduct of fatty acid transesterification with alcohols (biodiesel production). However, compared to the availability of other materials such as cellulose, there is little potential for using glycerol ethers as the main fuel constituent. US 6,015,440 teaches the use of glycerol ethers in conjunction with biodiesel (fatty acid esters), resulting in a reduction in the biodiesel mist point. US 5,820,640 describes the use of emulsions, blends of up to 50% by weight, fast pyrolysis oil (bio-oil) with diesel oil. The use of emulsifier is required for solvency of bio-oil to diesel. Despite the potential to produce large quantities of bio-oil by rapid pyrolysis, there are problems such as corrosion, ash content and sediment in the material. The use of the mixture in diesel engine has not been evaluated in the patent. US 5,858,030 requires the use of dimethoxy alkanes such as dimethoxyethane (DMET) as diesel oil additives. 1,2 Dimethoxyethane has a cetane number of 105, and can be produced in a renewable manner (oxidative coupling of dimethyl ether, which can be produced from the synthesis gas) but has a low flash point (0 ° C). US 6,578,870 teaches the use of oxygenate such as DMET to obtain a desired increase in cetane number and a second higher flash point oxygenate to obtain flash point of the desired mixture. Despite DMET's high cetane value, the flash point is low.

US 5,906,664 and US 6,270,541 teach the use of dimethyl ether (DME) as a fuel in diesel cycle engines. Methanol, water and DME compositions are claimed where the product has a phase and good ignition characteristics. DME can be produced renewable (biomass, synthesis gas) but has the disadvantage of low flash point (-41 ° C).

US 6,872,231 and US 7,300,476 teach the use of heavy oxygenates as diesel additives without the disadvantage of the low flash point. However, they are obtained from the oxidation of fossil hydrocarbons.

US 7,828,071 and US 7,374,587 teach the use of rendered hydrophobic starch as a fuel, including diesel engines. Starch, although renewable, is obtained to a lesser extent than cellulose, and lends itself to other uses as human food. Nor is it completely dissolved in diesel, which can make combustion difficult. US Patent 7,014,668 teaches the use of 5% to 100% by volume diesel engine, oxygen cycle, and optionally hydrocarbon fuels. The fuel of the invention has at least two distinct oxygenates with a total of 4 functional groups in the mixture comprising the alcohol, ether, ester, nitrate ether, aldehyde, ketone, acetal, peroxide and epoxide groups. More preferably, the fuel would have at least one compound from each group described above. US 4,992,605 deals with the hydroconversion of vegetable oils into hydrotreating catalysts, producing high cetane paraffins corresponding to the fatty acids of the original triglycerides. US Published Application US 2006/0186020 teaches the hydroconversion of triglycerides in diesel HDT reactors, blended up to 75% by weight of the load, generating the high cetane paraffins already blended with the fuel-specified diesel stream . US 7,279,018 deals with the hydrogenation of the same triglycerides, with additional isomerization in order to decrease the mist point of the product. The hydrogenation and isomerization product is then mixed with diesel and optionally with another oxygenate. The disadvantage of these processes is that vegetable oils and animal fats (triglycerides) are not as readily available as cellulose. US Published Application US 2006/0096158 teaches the use of cyclic ester or lactone to compose gasoline or diesel. Use as gasoline is preferable since single lactones without long chain bonds are of high octane. A lactone such as γ-Valerolactone may be obtained from levulinic acid, which may be obtained from hydroxymethylfurfural, which may be obtained from cellulose.

Other patents teach obtaining non-oxygenated products from renewable sources such as terpenoids or isoprenoids (biosynthetic derivatives of isoprene). US Patent 7,029,506 deals with the use of terpene β-carotene and the like (carotenoids, carotene precursors) as a diesel additive in small quantities. The compounds can be extracted from plants such as vetch and certain algae. The amount of carotene obtained from biomass is small. US Published Application US 2008/0083158 teaches the genetic modification of microorganisms to produce farnesane isoprenoid and derivatives, and use of these compounds as an additive or component of diesel. Farnesan is produced by cell culture, consuming sugars. Sugar is consumed by biomass growth, generating isoprenoid in small quantities. The multiplicity of patents for renewable diesel engine fuels shows that the art still needs new products, better ignition quality and obtained from higher yielding biomass. In general, products are poorly compatible with diesel and have low ignition capacity (eg ethanol), or are obtained from sources other than cellulosic (eg biodiesel), or are obtained by a large series of operations where there is yield loss (eg synthesis gas products obtained from biomass gasification).

The patents presented above discuss the use of renewable oxygenated compounds as major components of diesel engine fuel. Another possibility of application of renewable compounds is their use as ignition promoters.

Usually nitrated compounds are used as cetane improvers, mainly 2-ethylhexyl nitrate. Such compounds are usually derived from alcohols subjected to sulfonitic solutions (H2SO4 + HNO3) or other nitration methods known in the art. US 2,066,506 deals with the use of nitrates from polyhydric alcohol derivatives, such as 1,2-propylene glycol dinitrate. US 2,378,466 teaches the use of dinitrate of a poly 1,2-alkylene glycol as a cetane enhancer. US Patent 2,280,217 teaches that light alkyl nitrates such as ethyl nitrate (ethanol nitration product) can lead to flash point problems, with heavy nitrates having alkyl groups of more than 5, preferably more than 6, being preferred. carbons.

US 4,405,335 and US 4,406,665 deal respectively with the use of tetrahydrofurandiol dinitrate and tetrahydrofuranol nitrate as cetane improvers. US 4,659,335 teaches the use of monosaccharide and / or polysaccharide nitric acid esters, preferably nitrocellulose, plus a polyether as cetane improvers. US 4,705,534 addresses the use of various polynitrates (polynitrate esters) plus selected amines (as stabilizers) for increasing cetane in diesel and alcohol fuels. Polynitrates include ethylene glycol dinitrate, triethylene glycol dinitrate, nitroglycerine, tri, di and mononitrate cellulose and mixtures, among others. Nitrocellulose has limited hydrocarbon solubility and high viscosity. US Patent 5,096,462 deals with the use of nitric acid to dissolve cellulose from biomass, the current being then subjected to reaction with ethylene oxide (which alkylates some cellulose -OH groups, a reaction known as ethoxylation) and then the addition dehydrating agent such as H2SO4, plus HN03 eventually nitrating the product. The nitrated product is then incorporated into alcohol such as methanol or ethanol for use in diesel cycle engines. Use as a cetane additive in admixture with hydrocarbons is not claimed. US 5,454,842 deals with the use as cetane enhancer of fatty acid alcohol nitration products. The levels claimed for use in diesel are from 0.01% to 2% by mass.

Another possibility of obtaining useful derivatives directly from cellulose and / or sucrose involves the use of dianhydrohexitols. Dianhydrohexitols can be produced in the initial hydrolysis step, hydrogenation of hexoses (glucose for cellulose or starch, and glucose plus fructose for sucrose) to hexitols (glucitol or sorbitol for D-glucose, and sorbitol plus mannitol for fructose) and subsequent double dehydration resulting in dianhydrohexitols (isosorbide or 1,4: 3,6-Dianhydro-D-glucitol in the case of sorbitol and isomanide or 1,4: 3,6-Dianhydro-D-mannitol from mannitol) of formula Ο6Η10Ο4.

Dianhydrohexitols have the general structure (which describes the isosorbide, isomanide and isoidide isomers) according to Formula-1 below: Obtaining dianhydrohexitols by converting cellulosic biomass may be advantageous over obtaining ethanol, since all carbons present Cellulose (and sucrose) are converted into the final product, and separation schemes that do not involve distillation can be employed with significant energy efficiency. A selective process of obtaining isosorbide from cellulose using hydrated molten salts is known, see the article by Almeida, RM et al., Lignocellulosics Conversion in a Molten Salt Hydrate Medium in Platform Chemical / Fuel - Conference Catalysis for Ultra Clean Fuels - Dalian, China, 21-24 July 2008.

Dianhydrohexitols such as isosorbide have been used as a PVC plasticizer and renewable monomer. Derivatives such as isosorbide mononitrate and dinitrate are used for the treatment of myocardial infarction see article by Flèche, G .; Huchette, M., Isosorbide-preparation, properties and chemistry. Starch / Stärke, Vol. 38, No. 1 (1986), 26-30. Most hexitol dehydration processes are not selective. The dehydration process of sorbitol (glucitol) in acid medium leads to the initial formation of 1,4 and 2,5 anhydrous D-glucitol - both compounds are known as sorbitan. Sequentially anhydrous 1,4-D-glucitol may be dehydrated to 1,4-3,6 dianhydro-D-glucitol (isosorbide). The anhydrous 2.5-D-glucitol in turn does not suffer from the second dehydration. The mixture preferably containing the products of the first sorbitol dehydration is called sorbitan and is easily esterified with fatty acids. US 4,297,290 describes a process for obtaining sorbitan esters. Sorbitan esters used as surfactants are commercially available from various manufacturers Ullmann's Encyclopaedia of Industrial Chemistry 2002, Wiley-Surfactants / Nonionic Surfactants. DOI: 10,1002 / 14356007.a25-747. Sorbitan esters are used in diesel emulsion formulations as taught in US 4,477,258. 97% to 90% by volume of diesel are mixed with an aqueous ethanol and / or methanol solution of at least 5% of the total, and 3 to 10% by volume of an emulsifier mixture containing sorbitan monooleate and a surfactant. nonionic ethoxylated. US Patent 4,604,102 cites the use of Diesel cycle engine additive package containing (i) a combustion accelerator (organic nitrate) and (ii) sorbitan esters, reducing coking in the fuel injection nozzles. Preferably the amount of the mixture (i) and (li) in the fuel is from 0.01% to 1% by mass. US 6,156,081 teaches the formulation of another corrosion inhibiting and combustion facilitating additive package containing a surfactant - a sorbitan ester, a lubricating oil, and a saturated hydrocarbon containing 14 to 17 carbons is claimed. The claimed ratio of diesel to the additive package is 1: 200 to 1: 2000. US 6,527,816 teaches the use of isosorbide derivatives as a detergent for reducing gasoline deposits. The compounds are obtained from the reaction of isosorbide with compounds having epoxide group. Contents cited in the examples are 400 mg of the compound / L of gasoline.

US 6,648,929 and US 6,858,046 (continued) teach water-emulsified fuel compositions containing sorbitan esters as one of the components of the claimed additive package. US 7,182,797 teaches the use of a diesel additive package containing sorbitan oleate, a polyoxyethylene alcohol, an alkylene glycol and an amine.

An isosorbide alkyl ether, dimethyl isosorbide, is used as a component of personal care products and drug formulations, see article by Malhotra, S.V. et al. Applications of Corn-Based Chemistry. The Bridge (2007) vol. 37 (4).

Processes for producing dimethyl isosorbide are known in the current art, such as PCT publication WO 2007/096511, where isosorbide is treated with methyl chloride in the presence of an alkaline agent. US 4,585,649 teaches toothpaste formulations (which may be toothpaste, mouthwash, chewing gum, toothpicks, and dental floss) containing dianhydrohexitol monoethers and diethers. Isosorbide monoethers and diethers were effective in reducing the multiplication of plaque-causing bacteria. The state of the art shows the multitude of solutions presented for obtaining renewable fuels for diesel cycle engines. However, cellulose derived fuel other than ethanol is still sought, which has solubility in diesel, combustion capacity (high cetane), which is obtained in high yield and can be used in significant quantities in diesel.

Thus, the technique still requires compositions for use in diesel cycle engines based on dianhydrohexitol-derived compounds which have the desired characteristics of high density, flash point, oxygen content, boiling point and combustion capacity to provide its use. Also, as a particular case, the use of dianhydrohexitol dinitrates as a combustion accelerator is required.

Renewable source oxygenates which may be used as a component of Diesel cycle engine fuel in any amount, such compounds being described and claimed in the present application.

SUMMARY OF THE INVENTION

Broadly, the invention relates to the Diesel cycle engine fuel formulation comprising at least one dianhydrohexitol or derivative of Formula-2 below: Where R 'and R' are selected from -H, hydrocarbyl and -N02.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph illustrating the use of isosorbide dinitrate (ISDN) as a diesel ignition enhancer according to EXAMPLES 1 and 2. Figure 2 is a graph illustrating the use of mixtures of isosorbide, ethanol and water and optionally in admixture with dimethyl isosorbide (DMI) as diesel engine motor fuel, and the effect of ISDN on ignition of these mixtures according to EXAMPLES 3 and 4. Figure 3 is a graph illustrating the effect on ignition of the fuel, the addition of dimethyl isosorbide (DMI) in the mixture of isosorbide, ethanol and water, and in the mixture with diesel, according to EXAMPLES 5 and 6.

Figure 4 is a graph illustrating the effect of the addition of isosorbide dinitrate on ignition of dimethyl isosorbide (DMI) according to EXAMPLE 8. DETAILED DESCRIPTION OF THE INVENTION The invention consists of using dianhydrohexitols and their derivatives as diesel cycle engine fuels. More specifically, dianhydrohexitols and derivatives may be present in a small amount in the fuel, such as 0.05 mass%, or comprise the entire fuel.

The dianhydroxytols or derivatives of the present invention have the formula-2 below: Where R 'and R' are selected from -H (dianhydroxytol), hydrocarbons such as mono or dialkyl dianhydroxytols and -N02, forming the dianhydroxythols mono or dinitrate .

Dianhydrohexitols can be obtained from carbohydrates such as cellulose polysaccharides, starch, sucrose disaccharide, and galactose monosaccharides, among others. Preferably they are obtained from starch, cellulose or sucrose. More preferably, cellulose and / or sucrose. Cellulose and starch are polymers of the D-glucose monosaccharide (briefly considered only naturally occurring dextrogens monosaccharides, from which glucose is understood to mean D-glucose and hexitols as D-hexitols). Sucrose is a disaccharide composed of a fructose and a glucose. Cellulose, starch and sucrose may be hydrolyzed to the corresponding monosaccharides.

Both glucose and fructose may be hydrogenated to the corresponding sugar alcohol or hexitol. The hexitol glucose hydrogenation product is sorbitol, while fructose hydrogenation results in a mixture of sorbitol and mannitol. Iditol is a product of hydrogenation of hexose galactose.

Sorbitol, mannitol or iditol hexitols may in turn be dehydrated to anhydrohexitols and again dehydrated to dianhydrohexitols.

Dianhydrohexitols, isosorbide, isomanide and isoidide stereoisomers are respectively Formulas 1a, 1b and 1c: One of the preferred methods of obtaining dianhydroxytols is that described in Almeida, R.M. et al., 2008, cited above. The method consists of dissolving cellulose and / or sucrose in acid hydrated molten salt solution such as ZnCl2 and HCI, where hydrolysis products (monosaccharide (deos)) are obtained, which are then hydrogenated hexoses to hexitols after acid removal. in the molten salt medium and at the highest temperature there is double dehydration of the hexitol molecules to dianhydrohexitols, which are then recovered.The method employed in obtaining the dianhydrohexitols is not and should not be understood as a limiting factor of the invention and is being directed. for diesel cycle fuel compositions containing dianhydroxytols and derivatives Other dianhydroxytol production methods may be employed.

In addition to the dianhydrohexitols themselves, hydrocarbyl ethers and nitrates can be used as diesel engine fuels.

The hydrocarbyl ethers may have R 'and R "alkyl or cycloalkyl or phenyl as substituent groups. Also, only one of the groups R 'or R' may be substituted, one of the groups being ο Η. The size of the alkyl chain may be 1 (methyl), 2 (ethyl) or greater than 2. In practice, chain size limitations will be restricted to the desired fuel properties - too long chain size would result in high temperature. boiling and high point of mist. Further, the groups R 'and R' may both be alkyls of the same or different size.

In practice, the size of the hydrocarbyl substituent groups should not be considered as limiting the invention, where the novelty is the use of hydrocarbyl ethers as fuel compositions of diesel cycle engines.

In addition to dianhydrohexitol hydrocarbyl ethers, the invention also contemplates diesel cycle engine fuel compositions comprising dianhydrohexitol nitric ethers, such as dianhydroxitol dinitrates such as isosorbide dinitrate (ISDN). In addition to dinitrates, dianhydrohexitol mononitrates or mixtures of mononitrates and dinitrates may also be used. The preferred compound of the present invention for the diesel cycle engine fuel composition is isosorbide dimethyl ether, or dimethyl isosorbide (DMI) according to Formula-3 below: Dimethyl isosorbide has formula C8H1404, boiling point 234 ° C at 242 ° C, 36.74% oxygen content and specific mass of 1.16 at 20/4 ° C. The flash point is 118 ° C and the freezing point is less than -57 ° C.

Another component that can be used in diesel cycle engine fuel compositions is isosorbide itself. Isosorbide has a formula C6H10O4, an oxygen content of 43.79% and a specific mass of 1.377 at 20/4 ° C and a high boiling point above 270 ° C. However, the melting temperature is 72 ° C - which makes it necessary to add water or another solvent to obtain a soluble mixture under ambient conditions or to have a heated fuel injection system. The mist point of a mass mixture of 80% isosorbide, 10% water and 10% ethanol is -15 ° C. In addition to water and ethanol, another dianhydrohexitol derivative, such as dimethyl isosorbide, may be isosorbide solvent.

Despite the high boiling temperature of isosorbide, the oxygen content in the molecule is quite high. Thus, the formation of soot precursors in burning is disadvantaged. Moreover, the molecule is stable at elevated temperatures, unlike other oxygenates derived directly from cellulose, such as glucose, which tends to degrade when subjected to temperatures above 185 ° C. When using monosaccharides directly as fuel (see US Patent 4,425,136), in addition to special injection systems, the engine must be kept at a temperature of at least 500 ° C to avoid caramelization and deposit formation. Higher temperatures than typically encountered in diesel cycle injection systems and engines are not required in the present invention.

Hydrocarbyl derivatives of dianhydrohexitols are the preferred molecules of the present invention for use as a major component of diesel cycle engine fuel compositions. By principal component, it is understood that the mass content of the derivative is at least 10 mass%, preferably 25 mass%, more preferably greater than 50 mass%.

Dianhydrohexitol nitrates (nitric ethers) are preferably used in small quantities, not more than 10% by weight, characterizing their use as an additive rather than as a major component. The dianhydrohexitol dinitrate preferably claimed in the invention is isosorbide dinitrate. Preferably, when dianhydrohexitol nitrates are employed, the concentration is from 0.01% to 5% by weight, preferably from 0.05% to 2% by weight.

Dianhydrohexitol nitrates may be employed as the sole cellulose-derived components in the mixture, or may be employed in conjunction with other dianhydroxytols and derivatives. A particular claim is the use of isosorbide dinitrate in admixture with diesel (hydrocarbons). The Examples illustrate the present invention that dianhydrohexitol nitrates can be used as ignition enhancers by increasing the cetane (measured by IQT, ASTM D6890) of the fuel.

It has been found that the use of compounds such as isosorbide dinitrate is advantageous and it is soluble in typical hydrocarbons, conventional cetane improvers, monoalcohol nitrates such as 2 ethyl hexyl nitrate. Surprisingly, however, such conventional cetane improvers cannot be employed in larger amounts in more polar mixtures, such as the isosorbide, ethanol and water solution, with the dianhydrohexitol nitrates of the present invention being completely soluble. Accordingly, it is a claim of the present invention to use diesel cycle engine fuels containing dianhydrohexitol nitrates in combination with dianhydrohexitols and / or dianhydrohexitol hydrocarbons.

A preferred claim of the present invention is the use of the isosorbide dinitrate additive combined with dimethyl isosorbide as a fuel composition for use in diesel engine engines. Unexpectedly, the cetane gain for a given mass of isosorbide dinitrate was found to be significantly greater in the ignition of dimethyl isosorbide than in the state of the art hydrocarbon diesel ignition.

Several methods are known in the art to obtain dianhydroxytol derivatives, and are listed merely to indicate the feasibility of producing the dianhydroxytol derivatives required in the present invention as diesel cycle engine fuel components. Basically, these methods consist of the protection of the two hydroxyl groups (alcohol) present in dianhydroxytols.

Several methods are known for methylation of alcohols, including diols, and may be used to produce a dimethyl dianhydrohexitol such as dimethyl isosorbide. See article by Selva, M. and A. Perosa, Green chemistry metrics: A comparative evaluation of dimethyl carbonate, methyl iodide, dimethyl sulfate and methanol as methylating agents. Green Chemistry (2008) vol. 10 (4) pp. 457-464 2/32 cite the use of dimethyl carbonate, methyl iodide, dimethyl sulfate and methanol as methylating agents. The use of dimethyl carbonate, due to its characteristics of easy synthesis and methylation capacity, according to Tundo, P. et al. The Chemistry of Dimethyl Carbonate. Acc. Chem.Res. (2002) vol. 35 (9) pp. 706-716 may be a preferable method for obtaining dimethyl isosorbide. Since, in addition to the methyl product, the methylation by-product is methanol, it may be totally, partially or not removed from the product, such as dimethyl isosorbide. Thus, the dimethyl isosorbide mixture and methanol may be used as a component of diesel.

Several methods are known in the art for alkylating alcohols with olefins, generating alkyl ethers of the original alcohols, and which may be employed to produce alkyl and dialkyl dianhydroxytols, such as diethyl isosorbide. Ethylene to produce diethyl isosorbide may come from petroleum or from a renewable source such as ethanol dehydration. FCC naphtha is another possible source of olefins that can be used for alkylation of dianhydrohexitols, especially tertiary olefins such as isobutene. Typical alkylation catalysts are acid resins, zeolites, phosphoric acid, metonosulfonic acid, toluenesulfonic acid, tungstic acid, niobic acid, sulfuric acid, among others.

Several methods are known in the art for arylation of alcohols with aromatics, and may be used to generate aryl or diaryl ethers of dianhydroxytols, such as diphenyl isosorbide.

To obtain dianhydrohexitol nitrates, the commonly used method is nitration with sulfonitic solution, using HN03 as reagent and H2SO4 as dehydrating agent. Other methods are known in the art, such as the use of nitrogen pentoxide.

The methods employed to obtain dianhydrohexitol derivatives are not and should not be construed as limiting factors of the invention directed to combustible compositions comprising dianhydroxytols and derivatives. Other methods of obtaining dianhydroxytol derivatives from dianhydroxytols can be employed to obtain the same compounds useful in the invention. The methods described herein are given by way of illustration only.

Depending on the procedure for obtaining the dianhydrohexitols, there may be unreacted anhydrohexitols in the product composition and present in the diesel, but it has higher molecular weight and more free hydroxyls, making it difficult to use for diesel cycle engine components. The higher amount of free hydroxyls from anhydroxytols would also be unfavorable to obtain hydrocarbyl derivatives, since they would increase the consumption of the free hydroxyl protection agents (etherification, methylation, alkylation).

Sorbitan esters containing isosorbide esters may also be present in diesel. It is known in the art to use such compounds as surfactants even in mixtures of diesel and ethanol and methanol.

Other surfactants known in the art may be present in conjunction with the derivatives used in the diesel cycle engine fuel composition of the present invention. In addition to sorbitan esters are known in the state of the art anionic emulsifiers such as carboxylic acids, cationic as amine salts, nonionic, amphoteric, nitrogenous bases, etc. The biodiesel itself preferably that of castor oil may be used as a surfactant, co-solvent. U.S. Patent 3,490,237 cites various choking agents which may be used in conjunction with the dianhydroxytol derivative-containing diesel engine fuel of the present invention.

In addition to the use of pure dianhydrohexitol derivatives, such as dimethyl isosorbide, the present invention relates to the mixture of diesel derived from hydrocarbons and dianhydroxytol derivatives. The solubility of dianhydrohexitol derivatives such as dimethyl isosorbide may be less than 50% by mass in typical diesel (hydrocarbon) streams. Thus, it may be interesting to use an amount of co-solvent or surfactant such as biodiesel, preferably constituting less than 20% and more preferably less than 10% mass of the final diesel. This problem is diminished when using larger alkyl chains than methyl (C1), and the addition of co-solvent may not be necessary.

This problem can be avoided with mixtures of diesel and dianhydroxytol derivatives less than 50% in the case of dimethyl isosorbide, or smaller than the composition where two-phase formation occurs in the case of other dianhydroxytol derivatives.

This, however, depends on the motor load feeding procedure. If dianhydrohexitols and non-hydrocarbon derivatives are available for supply to the fuel tank, undesired insolubilization may occur if there is already a prior hydrocarbon content in the fuel tank. Thus, four cases are claimed in the present invention to avoid the problem of distributing dianhydroxytols and derivatives as diesel cycle engine fuels: I) dianhydroxytols and / or dianhydroxytols derivative contain additive package (co-solvent such as biodiesel and / or other surfactant); II) diesel already contains surfactant or co-solvent, such as biodiesel; III) Dianhydrohexitols and / or dianhydrohexitol derivatives are already distributed with diesel, so mixing with more diesel always results in less dianhydrohexitols and / or derivatives than the amount of saturation from which phase separation occurs. ; IV) Dianhydroxytols and / or dianhydroxytol derivatives are distributed with diesel and more surfactant or co-solvent.

The cosolvents and / or surfactants employed may be those known in the art, and may even be derived from anhydrous and dianhydrohexitols, such as sorbitan esters. Biodiesel, methyl or ethyl esters of fatty acids obtained from vegetable oils by transesterification may be used as co-solvents. Preferred biodiesel is castor oil because it contains hydroxyl in the fatty acid (ricinoleic acid) chain.

Another difference of the present invention compared to the state-of-the-art renewable cellulose fuel ethanol is that if phase separation occurs and alkyl dianhydroxytols such as dimethyl isosorbide, the more polar phase (DMI) are already in use. has enough cetane to use the product as diesel. Thus, the impact would be less than with ethanol (engine would stop running due to low ethanol ignition capacity).

Thus, a further distribution case may be possible than described above: distribution of dianhydroxytol derivatives as the sole fuel component of dianhydroxytols.

Another possible use case is the mixture of dianhydroxytols and dianhydroxytol derivatives, and optionally ethanol and water.

This mixture may also contain biodiesel and hydrocarbon diesel, in which case ethanol and water will be in smaller proportions than the other components of the mixture. See in this regard the composition of Example 7.

The hydrocarbyl derivatives of dianhydrohexitols are capable of solubilizing water. In the case of dimethyl isosorbide they are capable of forming solutions with water in any amount. Thus, water may be added to increase fuel economy and lower the temperature of the diesel cycle engine, the effect of which is known to decrease combustion NOx emissions.

Another important gain of cellulose derivatives such as dianhydrohexitol derivatives is the increased oxygen content in the diesel cycle engine fuels of the present invention. The presence of oxygen in the fuel above a certain threshold is known to inhibit the formation of soot. Renewable oxygenates used in diesel cycle engines, such as ethanol, usually have low specific mass, and consequently low energy density. The specific mass of 20/4 ° C of dimethyl isosorbide is 1.16, against 0.7915 of anhydrous ethanol, and its energy content is 28 MJ / L, compared to only 22 MJ / L of ethanol, although DMI oxygen content (36.74 mass%) is higher than ethanol (34.73 mass%). In addition, DMI cetane (IQT) is 51.77, while ethanol is only 8.

Even isosorbide has a higher energy content: specific mass 20/4 ° C of 1,377, oxygen content of 43.79% mass and energy content of 27.6 MJ / L.

Thus, the gain of the present invention is significant: use as diesel cycle fuel of higher density cellulose-derived oxygenates, higher oxygen content, higher energy density than ethanol, higher affinity for hydrocarbons, and higher cetane number. The mode of preparation of the fuel compositions of the invention is by simply mixing the dianhydroxytol components and derivatives with hydrocarbon diesel, biodiesel, ethanol or water, whether or not agitated. In case of phase separation, surfactants and / or co-solvents may be added as described earlier in this report. The invention will be illustrated by the following Examples, which are not to be construed as limiting. EXAMPLE 1 Example 1 is a Control Example. The effect of the most commonly used cetane improver, 2 ethyl.hexyl nitrate (2EHN), was evaluated with typical hydrotreated diesel. Diesel had a 20/4 ° C density of 0.8798, a sulfur content of 154 ppm and a gas chromatography-mass spectrometry (GC / MS) analysis, 16.5% paraffin mass, 40.6 % naphthenic mass, 27.6% monoaromatic mass, 12.2% diaromatic mass and 2% triaromatic mass.

Several levels of 2EHN were added to hydrotreated diesel and the ignition delay, expressed as estimated cetane or IQT, was determined by the ASTM D6890 IQT (Ignition Quality Tester) method. Table 1 shows the IQT values of diesel and diesel and 2EHN mixtures. The result points to the typical increase of 2 cetane points to 500 ppm from 2EHN. EXAMPLE 2 This Example illustrates the preparation and use of isosorbide dinitrate (ISDN) as a combustion promoting additive in diesel compositions.

Sulfonitic solution containing 100 mL of 98% H2 SO4 and 70 mL of 68% HNO3 was prepared. The mixture was kept stirred in a cold bath at 0 ° C and 160 g of trichloromethane were added. A solution of isosorbide, 25 g dissolved in 6.5 g of water was added dropwise so that the temperature of the mixture did not exceed 8 ° C. After 30 minutes the mixture was added to 300 g of ice. The organic phase was separated, washed with sodium bicarbonate solution to remove dissolved acid and the solvent removed by rotavap. About 32 g of product was recovered. The sample was cooled resulting in crystallization. An elemental analysis of the material was performed, obtaining C = 30.77% H = 3.41% 0 = 53.97% N = 11.77%. The isosorbide dinitrate (ISDN) formula is C6H808N2, which is equivalent to 30.52% C, 3.41% H, 54.20% O and 11.86% N. Comparison shows that ISDN was obtained with reasonable purity.

Several ISDN contents were added to the hydrotreated diesel of Example-1. ISDN solubilized in diesel in all proportions employed. The ignition delay of diesel and ISDN mixtures is presented in Table 2.

The results of using 2EHN and ISDN as combustion promoters are shown in Figure 1. At high levels (0.5%) cetane gain is similar. The result shows that nitrated isosorbide can be used as a combustion promoter. EXAMPLE 3 The Example shows the use of isosorbide as a fuel in a diesel engine.

Dissolution of isosorbide in water and ethanol was obtained. The proportion was 80% isosorbide mass, 10% ethanol mass, 10% water mass. Isosorbide dinitrate was added to the isosorbide mixture, ethanol and water. The results of the IQT analysis for the ISDN mixtures are presented in Table 3. The 2EHN combustion promoter was also used at 0.1% mass, 0.5% mass and 2% mass. At 0.5% by mass and 2% by mass there was phase separation (turbidity in the mixture and further formation of the top support phase, compatible with the volume of 2EHN added). The IQT analysis of the isosorbide, ethanol and water mixture with 0.5% mass of 2EHN was 10.32. Example 3 shows that the 2EHN combustion enhancer commonly employed in the art is not suitable for more polar fuel blending. EXAMPLE 4 This Example shows the use of dimethylisosorbide (DMI) as a combustion enhancer in polar fuel. The methylation product of isosorbide, dimethyl isosorbide (DMI), was added to the mixture of Example 3 in a proportion by 50% by mass. Thus, the resulting mixture had 50% DMI, 40% isosorbide, 5% water and 5% ethanol. To this mixture were also added different ISDN contents. The IQT results are presented in Table 4. Dimethyl isosorbide (DMI) has a specific mass of 1.16 to 20/4 ° C, flash point of 118 ° C, boiling point of 234 ° C to 242 ° C and freezing point below -57 ° C. Figure 2 shows the results of Examples 3 and 4. The IQT cetane value of the isosorbide, ethanol and water mixture is low and little increases with the addition of ISDN. The addition of DMI to the mixture improved the initial cetane and even the response to ISDN. EXAMPLE 5 Isosorbide dimethyl ether (DMI) was mixed in various proportions to the mixture of isosorbide, ethanol and water from Example 3. The results of this mixture and pure DMI without addition of ISDN are shown in Table 5. Example shows that DMI cetane is sufficient for use as fuel, and that mixtures of isosorbide, ethanol, water and DMI can be obtained with cetane greater than 40, even without combustion promoter.

Additionally, DMI has a C8Hi404 composition, which is equivalent to an oxygen content of 34.73% by mass. It is known that oxygen levels of this order in ignition in diesel cycle engines inhibit the emission of soot in the combustion gases. EXAMPLE 6 The isosorbide dimethyl ether (DMI) was mixed with hydrocarbon diesel in the proportions of 25%, 50% and 75% mass of DMI. At 25% mass the isosorbide was completely soluble, while in 50 and 75% there was phase separation. 8 g castor oil methyl ester (castor biodiesel) was then added to each 100 g DMI mixture and diesel as co-solvent for complete mixing. Table 6 presents the IQT results of the mixtures.

Between 25% and 50% DMI mass occurred in the formation of two phases, which can be prevented by addition of co-solvent with lower oxygen content than DMI, such as biodiesel, or surfactant. Example 6 shows that it is possible to obtain diesel and DMI solutions without phase separation and without co-solvent, provided that less than 50% mass of DMI. Further, that DMI may be added to diesel and mixed in the fuel tank itself, provided that diesel has amount of co-solvent or DMI has amount of co-solvent or other surfactant. Figure 3 shows the positive effect of DMI addition on cetane increase in both the isosorbide mixture (Example 5) and the diesel mixture (Example 6). EXAMPLE 7 Example shows a fuel composition comprising castor bean biodiesel, DMI, diesel, isosorbide, water and ethanol, in the proportions shown in Table 7. The IQT result for the mixture of Example 7 was 38.19.

It has been observed in this and other mixtures that the summed amounts of biodiesel and DMI should be greater than the summed amounts of isosorbide, ethanol and water (if present) to ensure a one-phase fuel composition. EXAMPLE 8 Mixtures of DMI with the ISDN ignition promoter are shown in Example 8. Table 8 shows the IQT results of the mixtures. Figure 4 shows the results of cetane increase when mixing ISDN with DMI. Significant IQT values can be obtained. Surprisingly, the ignition promoter gain (increase in IQT units per% added mass) is significantly higher in DMI than in diesel (hydrocarbon) and isosorbide. EXAMPLE 9 In Example 9 estimates of the solubility of other hydrocarbyl derivatives of isosorbide in hydrocarbons are compared to dimethyl isosorbide and isosorbide. Table 9 shows results for estimating the octanol / water partition coefficient. Higher partition coefficient means higher affinity for the organic phase. The various classes of isosorbide hydrocarbyl derivatives, including mono and dialkyl isosorbides, mono and diaryl, and alkyl, aryl isosorbides and dicycloalkyl isosorbides, are shown in Table 9.

Estimates show the better solubility of isosorbide derivatives in hydrocarbons with increasing chains attached to at least one of the original isosorbide OH groups. EXAMPLE 10 To a volume of 50 mL of dimethyl isosorbide (DMI) was added increasing amounts of water or ethanol and water solutions. Water and ethanol were soluble in DMI at all dilutions employed (from 10% to 90% mass DMI in water and from 10% to 90% mass DMI in ethanol). The addition of 1% water mass in diesel results in a 0.5 cetane drop. For dimethyl isosorbide, up to 20% water mass may be added, or as long as the IQT is greater than 40 without the addition of ISDN. Additions of more water make it necessary to add ignition enhancer, preferably isosorbide dinitrate. Ethanol has low cetane (8), but can be mixed with DMI up to about 20 mass%, or as long as the IQT is greater than 40 without addition of ISDN. Additions of higher ethanol make it necessary to add ignition enhancer, preferably isosorbide dinitrate.

DMI, water, ethanol and ISDN compositions may be employed as the diesel cycle engine fuel of the present invention so as to maintain the IQT above 40. EXAMPLE 11 Amounts of 50 ml of dimethyl isosorbide (DMI) were added. increasing amounts of biodiesel used in Example 6. Dimethyl isosorbide was soluble in biodiesel at all concentrations employed (from 10% to 90% mass DMI in biodiesel). Example 11 shows that diesel engine fuel containing DMI and biodiesel can be formulated.

The Examples show the feasibility of the invention - using isosorbide and diesel engine engine derivatives - and are merely illustrative and should not limit the scope thereof.

Claims (36)

1. DIESEL CYCLE ENGINE FUEL COMPOSITIONS, characterized in that they comprise at least one dianhydrohexitol compound of formula 2 and / or its hydrocarbyl ether or nitric ether derivatives, where the substituents R 'and R "are both H, or one or both from R 'and R' is alkyl, cycloalkyl or phenyl, or one or both are -N02. Compositions according to claim 1, characterized in that the hydrocarbyl groups are selected from mono and dialkyl, mono and diaryl, and alkyl, aryl and dicycloalkyl. Compositions according to claim 1, characterized in that when R '= R' = Η, dianhydrohexitol is isosorbide. Compositions according to claim 1, characterized in that when R '= R' = CH 3) dianhydrohexitol is dimethyl isosorbide (DMI). Compositions according to claim 1, characterized in that they comprise as main component a hydrocarbyl derivative with a mass content of the derivative of at least 10% by mass. Compositions according to claim 5, characterized in that said hydrocarbyl derivative comprises 25% by mass of said combustible composition. Compositions according to claim 5, characterized in that said hydrocarbyl derivative comprises more than 50 mass% of said combustible composition. Compositions according to claim 7, characterized in that said hydrocarbyl derivative comprises dimethyl isosorbide (DMI). Compositions according to claim 8, characterized in that they comprise from 10% to 90% by weight of dimethyl isosorbide (DMI) in alkyl fatty acid esters (biodiesei). Compositions according to claims 5, 6, 7 and 8, characterized in that the dimethyl isosorbide is added to a hydrocarbon fuel selected from diesel. Compositions according to claim 10, characterized in that they further include a co-solvent or surfactant, such as the biodiesel, constituting less than 20% or less than 10% by weight of the final diesel. Compositions according to claim 1, characterized in that when both R 'and R' are -N02 the dianhydrohexitol is isosorbide dinitrate (ISDN). Compositions according to claim 12, comprising from 0.01% to 5% by weight of the isosorbide dinitrate derivative. Compositions according to claim 13, comprising from 0.05% to 2% by weight of the isosorbide dinitrate derivative. Compositions according to claims 12, 13 and 14, characterized in that the isosorbide dinitrate is added to a hydrocarbon fuel selected from diesel. Compositions according to claims 12, 13 and 14, characterized in that it comprises isosorbide dinitrate added to dianhydrohexitols and / or dianhydrohexitol hydrocarbyl ethers. Compositions according to claim 16, characterized in that it comprises isosorbide dinitrate added to dimethyl isosorbide. Compositions according to claim 17, characterized in that the cetane gain shown for a given mass of isosorbide dinitrate is significantly greater in the ignition of dimethyl isosorbide than in the ignition of state of the art hydrocarbon diesel. Compositions according to claims 1 to 18, further comprising a surfactant selected from sorbitan esters, anionic emulsifiers, including carboxylic acids, cationic emulsifiers, including amine salts, nonionic emulsifiers, amphoteric, nitrogenous bases. and the like. Compositions according to Claims 1 to 18, characterized in that they comprise castor biodiesel as surfactant. Compositions according to claims 1 to 18, characterized in that they comprise castor bean biodiesel as a co-solvent. Compositions according to any one of claims 1 to 18, characterized in that the fuel distribution comprises: i) dianhydrohexitols and / or dianhydroxytol derivatives added from additive package selected from co-solvent such as biodiesel and / or other surfactant; or ii) diesel, to be mixed in a tank with dianhydrohexitol derivatives, was added as a surfactant or co-solvent, selected from biodiesel or surfactant; (iii) dianhydroxytols and / or dianhydroxytol derivatives are distributed with diesel, so mixing with more diesel always results in less dianhydroxytols and / or derivatives than the amount of saturation from which phase separation occurs; or iv) dianhydroxytols and / or dianhydroxytol derivatives are distributed with the diesel and further surfactant or co-solvent; so that when directing a stream of dianhydrohexitols and derivatives to the fuel tank in at least one of the cases i), ii), iii) or iv) the problem of phase separation of dianhydrohexitols and derivatives used as fuels is avoided of the diesel cycle engine. Compositions according to any one of claims 1 to 18, characterized in that they comprise distribution of dianhydroxytol derivatives as the sole fuel component of dianhydroxytols. Compositions according to claims 1, 2 and 7, characterized in that the dianhydrohexitol or derivative is added with water up to 20% by mass, maintaining the IQT of at least 40, and above 20% by weight with addition of ISDN. Compositions according to claim 24, characterized in that between 0.01% and 5% mass of isosorbide dinitrate (ISDN) is added. Compositions according to claim 25, characterized in that between 0.05% and 2% mass of isosorbide dinitrate (ISDN) is added. Compositions according to claims 1, 2 and 7, characterized in that the dianhydrohexitol or derivative is added with ethanol, maintaining an IQT of at least 40. Compositions according to claim 27, characterized in that between 0.01% and 5% mass of isosorbide dinitrate (ISDN) is added. Compositions according to claim 28, characterized in that between 0.05% and 2% mass of isosorbide dinitrate (ISDN) is added. Compositions according to claims 1, 2 and 7, characterized in that the dianhydrohexitol or derivative is added with water and ethanol, maintaining the IQT of at least 40. Compositions according to claim 30, characterized in that between 0.01% and 5% mass of isosorbide dinitrate (ISDN) is added. Compositions according to claim 31, characterized by the addition of 0.05% to 2% mass of isosorbide dinitrate (ISDN). Compositions according to any one of claims 24 to 32, characterized in that the dianhydrohexitol is isosorbide. Compositions according to claims 24 to 32, characterized in that the isosorbide is added from the hydrocarbyl dimethyl isosorbide derivative (DMI) in any proportion. Compositions according to claim 1, comprising a major proportion of dimethyl isosorbide (DMI), biodiesel and diesel hydrocarbon and a smaller proportion of isosorbide, water and ethanol, characterized in that the DMI + biodiesel content is greater than the content. of water plus ethanol. Compositions according to Claim 1, characterized in that they inhibit soot formation in diesel cycle engines by containing at least 10% by weight of said dianhydroxytols and derivatives according to formulas 1, 2 and 3.