ITMI20092202A1 - COMPOSITION OF GAS OIL INCLUDING DIETYL CARBONATE FROM BIOETHANOL AND VEGETABLE OIL - Google Patents

Description

DIESEL COMPOSITION INCLUDING DIETHYL CARBONATE FROM BIOETHANOL AND HYDRO-TREATED VEGETABLE OIL

*** *** ***

DESCRIPTION

The present invention relates to a gas oil composition comprising diethyl carbonate and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)].

More particularly, the present invention relates to a diesel oil composition comprising diethyl carbonate obtained from bioethanol and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)].

The above composition can be advantageously used as a fuel for diesel engines.

It is known that the emissions produced by the combustion of fossil fuels containing carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), volatile organic compounds and particulate matter (PM ), besides being harmful, are the main cause of environmental problems such as, for example, the greenhouse effect (in the case of nitrogen and carbon oxides) and acid rain (in the case of sulfur and nitrogen oxides) .

In recent years, the increase in the cost of crude oil and a matured awareness of the environmental problems described above have strengthened the need to identify alternative, biodegradable and renewable energy sources.

Consequently, the progressive replacement of fuels deriving from fossil energy sources such as, for example, coal, oil, natural gas, with fuels deriving from alternative, biodegradable and renewable energy sources, such as, for example, vegetable oils, animal fats, biomass, algae, is becoming of increasing interest worldwide.

Efforts have therefore been made in the art in order to obtain fuels from renewable energy sources.

For example, with regard to fuels for diesel engines, the use of methyl esters of fatty acids (FAME) and hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)] is known as they are, or in a mixture with diesel fuel, as well as gas oil blends including bioethanol.

Methyl esters of fatty acids (FAME), generally known as biodiesel, can be produced starting from crude vegetable oil (triglycerides) obtained by pressing the seeds of oil plants such as, for example, rapeseed, palm, soybean, sunflower, mustard, as well as from other sources of triglycerides such as, for example, algae, animal fats, or used or waste vegetable oils, by transesterification in the presence of methanol and an acid or basic catalyst.

However, the use of said methyl esters of fatty acids (FAME) as they are, or mixed with diesel, can present some problems in particular related to:

- poor oxidation stability, which can become particularly critical if the product remains inside the tank for a long time;

- worst cold properties in terms of cloud point [â € œcloud pointâ € (CP)], pour point [â € œpour pointâ € (PP)] and filter clogging point [â € œcold filter plugging pointâ € (CFPP)] which are generally higher than diesel derived from fossil fuels;

- increase in emissions of nitrogen oxides (NOx).

The above problems are known and have been described, for example, by Knothe G. in the review â € œSome aspects of biodiesel oxidative stabilityâ €, published in â € œFuel Processing Technologyâ € (2007), Vol. 88, pg. 669-677; by Tang and others in the article â € œFuel properties and precipitate formation at low temperature in soy-, cottonseed- and poultry fat-based biodiesel blendsâ €, published in â € œFuelâ € (2008), Vol. 87, pg. 3006-3017; by Krahl J. and others in the article â € œComparison of exhaust emissions and their mutagenicity from the combustion of biodiesel, vegetable oil, gas-to-liquid and petrodiesel fuelâ €, published in â € œFuelâ € (2009), Vol. 88, pg. 1064-1069.

Hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)], also known as â € œgreen dieselâ €, are produced by hydrogenation / deoxygenation of a material deriving from renewable sources including triglycerides and free fatty acids, in the presence of hydrogen and of a catalyst as described, for example, by Holmgren J. and others in the article â € œNew developments in renewable fuels offer more choicesâ €, published in â € œHydrocarbon Processingâ €, September 2007, pg. 67-71. This article highlights the best characteristics of these hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)] compared to the methyl esters of fatty acids (FAME), in particular, in terms of better oxidation stability and better cold property. Furthermore, these hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)] do not have the problem of higher emissions of nitrogen oxides (NOx).

However, due to the lack of oxygen atoms in these hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)], their use in diesel engines mixed with diesel in quantities of less than 5% by volume with respect to the total volume of this mixture does not bring significant benefits as regards particulate emissions (PM). On the other hand, there is a trend towards a decrease in particulate emissions (PM), when said hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)] are used in diesel engines mixed with diesel in quantities equal to or greater than 20% in volume with respect to the total volume of said blend as described, for example, by L. Rantanen and others in the article â € œNExBTL â € “Biodiesel Fuel of the Second Generationâ €, published in SAE Report 2005-01-3771.

However, these hydrotreated vegetable oils [â € œhydrotreated vegetable oilsâ € (HVO)] generally have a high cetane number (generally higher than 60), and this characteristic may somewhat limit their ability to reduce emissions. of particulate matter (PM). In fact, it is known that, like other characteristics, fuels with a high cetane number have a greater tendency to the formation of particulate matter (PM).

As is well known, the ignition aptitude of fuels for diesel engines is measured by their ignition delay time, that is the time interval that occurs in a diesel engine between the start of injection and the start of combustion: the cetane number is a measure of this delay at ignition.

The shorter the ignition delay, the higher the cetane number of the fuel used and, therefore, the less fuel will be in the combustion chamber when ignition begins.

Consequently, a high cetane number is preferable because it ensures rapid ignition of the mixture and therefore smoothness of operation, especially in cold starting. However, beyond certain values of the cetane number, a further increase of the same is devoid of practical effects, on the contrary it can be disadvantageous as the time necessary for sufficient mixing of the fuel with the air may be lacking with a consequent increase in the exhaust smoke and particulate emissions (PM), as reported, for example, in â € œInternal Combustion Engines for Vehiclesâ € (1995), by R. Della Volpe and M. Migliaccio, published by Liguori.

As mentioned above, known in the art are also blends of bioethanol with diesel, usually known as â € œe-dieselâ €. However, said bioethanol / gas oil blends may present some problems such as, for example, non-homogeneity, low cetane number, low flammability temperature.

One of the main problems, i.e. the non-homogeneity is linked to the fact that, since bioethanol is immiscible with diesel over a wide temperature range, there is a phase separation and the mixtures obtained are therefore unstable as described, for example, by Lapuerta and others in the article â € œStability of diesel-bioethanol blends for use in diesel enginesâ €, published in â € œFuelâ € (2007), Vol. 86, pg. 1351-1357. In said article, the conditions under which said mixtures are stable are studied. The stability of these mixtures is mainly influenced by three factors: the temperature, the water content and the initial content of ethanol. The results obtained show that the presence of water in the mixtures, the low temperatures, and the high content of ethanol, favor the phase separation, while the presence of additives such as, for example, surfactants and / or co-solvents, have an opposite effect.

As mentioned above, a further problem related to the use of bioethanol mixed with diesel fuel is the low cetane number of said bioethanol / diesel fuel mixture which causes a high ignition delay in internal compression diesel engines. One way to solve this problem is described, for example, in the European patent application EP 1,721,954.

European patent application EP 1,721,954 describes a diesel composition comprising: a diesel as base material; ethanol in a quantity comprised between 5% by weight and 30% by weight with respect to the total quantity of said diesel; ethyl nitrite or, alternatively, ethyl nitrate, in a quantity between 0.5% by weight and 7% by weight with respect to the total quantity of said diesel. Said ethanol is preferably obtained from vegetable material, for example from the fermentation of vegetable substances such as agricultural crops including sugar cane and maize. The above diesel composition, thanks to the presence of ethyl nitrite or ethyl nitrate, is said to have an excellent ignition aptitude (â € œexcellent ignitabilityâ €) despite the presence of ethanol. Said patent application does not contain data relating to the flammability of the aforementioned diesel composition.

It is also known in the art that the use of diethyl carbonate mixed with diesel fuel leads to a significant reduction in particulate emissions (PM).

For example, Miloslaw and others in the article â € œThe influence of synthetic oxygenates on Euro 4 diesel passenger car exhaust emissionsâ € published in SAE Report 2008-01-2387, report, among others, the results of an experiment carried out on a Euro 4 car according to the NEDC cycle and according to the FTP-75 cycle with the use of a diesel fuel containing 5% by volume of diethyl carbonate with respect to the total volume of the diesel / diethyl carbonate mixture, which corresponds to an oxygen content in the mixture equal to about 2.4% by weight. In the case of the NEDC cycle, a reduction in particulate emissions of 32% is reported, combined with an increase in nitrogen oxide (NOx) emissions of only 4%, without significantly affecting fuel consumption (increase of 0, 5%). In the case of the FTP-75 cycle, on the other hand, a reduction in particulate emissions of 19% is reported, with an increase in nitrogen oxide (NOx) emissions of 13% and an increase in consumption of 2.6%.

Ren and others in the article â € œCombustion and emissions of a DI diesel engine fueled with diesel-oxygenate blendsâ €, published in â € œFuelâ € (2008), Vol. 87, pg.

2691-2697, report the results of an experiment carried out on a diesel bench engine with direct injection, with a displacement equal to 903 cm <3>, at 2000 rpm, with the use of a diesel containing different oxygen compounds in varying percentages . For mixtures of diesel fuel with diethyl carbonate and diesel fuel with dimethyl carbonate, the reduction of particulate emissions (PM), measured by means of an opacimeter, is greater than 35% compared to diesel oil as it is. In this article it is also reported that, with the same oxygen content, the amount of reductions in particulate emissions is more consistent for mixtures of diesel with diethyl carbonate than for mixtures of diesel with dimethyl carbonate.

Diethyl carbonate is a non-toxic compound, having a density of 975 kg / m <3> and an oxygen content of 40.7% by weight, which compared to other oxygenated components for fuels such as, for example, dimethyl carbonate , ethanol, has the advantage of having a more favorable diesel / water distribution coefficient. A further advantage of diethyl carbonate compared to other oxygenated components for fuels, for example, methyl-tert-butyl ether (MTBE), is that, if accidentally released into the environment, it slowly transforms by hydrolytic decomposition into carbon dioxide and ethanol , which are compounds with low environmental impact. However, diethyl carbonate has a low cetane number: in this regard, Miloslaw and others in the article â € œThe influence of synthetic oxygenates on Euro 4 diesel passenger car exhaust emissionsâ € published in SAE Report 2008-01-2387, above cited, report a cetane number of diethyl carbonate equal to 13.8.

The Applicant has noted that the use of hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] in compositions comprising diesel in high quantities (e.g., greater than or equal to 20% by volume with respect to the total volume of said compositions) it may cause some inconvenience. In particular, the Applicant noted that the use of hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] in high quantities can negatively affect the characteristics of the starting diesel such as, for example, density and cetane number .

In order to increase the quantity of components of biological origin in said compositions, the Applicant has set itself the problem of using high quantities (e.g., greater than or equal to 20% by volume with respect to the total volume of said compositions) of hydrotreated vegetable oil (â € œhydrotreated vegetable oilâ € (HVO) in compositions including diesel, avoiding the drawbacks described above.

The Applicant has now found that the addition of diethyl carbonate deriving from bioethanol in compositions comprising gas oil and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] in high quantities, allows to obtain compositions which do not show the above mentioned drawbacks. and can be advantageously used as a fuel for diesel engines.

In particular, the Applicant has found that the addition of said diethyl carbonate, in addition to increasing the percentage of components of biological origin in said compositions comprising gas oil and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] in high quantities , Is able to improve some characteristics such as, for example, density and cetane number. Furthermore, the addition of said diethyl carbonate does not negatively affect the other characteristics of said compositions comprising gas oil and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] in high quantities such as, for example, cold properties as a point of clouding [â € œcloud pointâ € (CP)] and filter clogging point [â € œcold filter plugging pointâ € (CFPP)]. Furthermore, the addition of said diethyl carbonate allows to compensate for the absence of oxygen in said compositions comprising diesel and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] in high quantities and, consequently, to further reduce the particulate matter (PM) emissions.

Therefore, the object of the present invention is a composition of gas oil comprising:

- from 5% by volume to 79.9% by volume, preferably from 30% by volume to 68% by volume, with respect to the total volume of said composition, of at least one gas oil;

- from 0.1% by volume to 20% by volume, preferably from 2% by volume to 10% by volume, with respect to the total volume of said composition, of at least one diethyl carbonate;

- from 20% by volume to 75% by volume, preferably from 30% by volume to 60% by volume, with respect to the total volume of said composition, of at least one hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)]; wherein said diethyl carbonate is obtained from bioethanol.

For the purpose of the present description and of the following claims, the definitions of the numerical ranges always include the extremes unless otherwise specified.

Any diesel fuel can be used for the purpose of the present invention. In particular, said diesel oil can be chosen both from diesel fuels that fall within the specifications of diesel fuel for motor vehicles according to the EN 590: 2009 standard, and from diesel oils that do not fall within these specifications.

Generally, gas oil is a mixture containing aliphatic hydrocarbons such as, for example, paraffins, aromatic hydrocarbons and naphthenes, typically having from 13 to 30 carbon atoms. Generally, the distillation temperature of gas oil is between 160 ° C and 380 ° C.

In accordance with a preferred embodiment of the present invention, said gas oil can have a density, at 15 ° C, determined according to EN ISO 3675: 1998, between 800 kg / m <3> and 870 kg / m <3 >, preferably between 820 kg / m <3> and 850 kg / m <3>.

In accordance with a preferred embodiment of the present invention, said gas oil can have a flash point, determined according to the EN ISO 2719: 2002 standard, greater than or equal to 55 ° C, preferably greater than or equal to 65 ° C.

In accordance with a preferred embodiment of the present invention, said gas oil can have a cetane number, determined according to the EN ISO 5165: 1998 standard, greater than or equal to 49, preferably greater than or equal to 51.

Said diethyl carbonate can be obtained by various processes known in the art for the synthesis of diethyl carbonate from ethanol.

In accordance with a preferred embodiment of the present invention, said diethyl carbonate can be obtained by means of a process which comprises the transesterification of at least one dialkyl carbonate such as, for example, dimethyl carbonate, or of at least one cyclic carbonate such as, for example, ethylene carbonate, propylene carbonate, with bioethanol, in the presence of at least one catalyst. Said process is particularly advantageous as it uses non-toxic carbonylating agents (i.e. dialkyl carbonate, or cyclic carbonate).

Said transesterification can be carried out at a temperature between 50 ° C and 250 ° C, in the presence of at least one catalyst which can be chosen from: basic inorganic compounds such as, for example, hydroxides (e.g., sodium hydroxide), alkoxides (e.g., sodium methoxide); alkali metals or alkali metal compounds; basic organic compounds such as, for example, triethylamine, triethanolamine, tributylamine; compounds of tin, titanium, zirconium, or thallium; heterogeneous catalysts such as, for example, zeolites, modified zeolites such as, for example, titanium silicalites (e.g., titanium silicalite TS-1 treated with potassium carbonate); metal oxides belonging to the IVA group and / or to the IVB group of the Periodic Table of the Elements, preferably supported on a porous support; rare earth oxides.

In the case of the production of diethyl carbonate by transesterification of dimethyl carbonate with bioethanol, the coproduced methanol can be removed by distillation as azeotrope with dimethyl carbonate, while the diethyl carbonate produced can be recovered by separating it by distillation from the excess of ethanol and methyl -ethyl carbonate which is the reaction intermediate.

In the case of the production of diethyl carbonate by transesterification of ethylene carbonate or propylene carbonate with bioethanol, the diethyl carbonate produced can be recovered by separating it by distillation from the excess of bioethanol, from the unreacted alkylene carbonate and from the alkylene co-product glycol.

More details relating to the above transesterification process are described, for example, in the American patents US 4,181,676, US 4,062,884, US 4,661,609, US 4,307,032, US 5,430,170, US 5,847,189, or in the Japanese patent application JP 2004/010571, or by Tatsumi and others in â € œChemical Communicationâ € (1996), pg. 2281, or by Anastas et al in â € œGreen Chemistry: Theory and Practiceâ € (1998), Oxford University Press, pg. 11.

In accordance with a further preferred embodiment of the present invention, said diethyl carbonate can be obtained by means of a process which comprises the reaction of urea with bioethanol, in the presence of at least one catalyst. This process uses urea as the carbonylating agent, which is a non-toxic, low cost and readily available product. Furthermore, the possibility of recycling the ammonia co-produced in the production of urea gives the synthesis process a high degree of sustainability as it uses bioethanol and carbon dioxide.

The above process first involves the formation of ethyl carbamate which is subsequently converted into diethyl carbonate. Said process, which can be both a single-stage process or a two-stage process, can be carried out at temperatures between 100 ° C and 270 ° C, removing the reaction ammonia, in the presence of at least one catalyst that can be chosen from: homogeneous catalysts such as, for example, tin compounds; heterogeneous catalysts such as, for example, metal oxides, or powdered or supported metals; bifunctional catalytic system, consisting of a Lewis acid and a Lewis base; mineral acids or bases.

More details relating to the aforementioned production process of diethyl carbonate by reaction of urea with bioethanol, can be found, for example, in the following documents.

For example, in the European patent EP 0061672 and in the international patent application WO 95/17369, synthesis processes of dialkylcarbonates from urea and alcohol are described, both in a single step and in two successive steps, in the presence of tin compounds such as catalysts such as, for example, dibutyl-tin oxide, dibutyl-tin dimethoxide, at a temperature between 120 ° C and 270 ° C, removing the reaction ammonia and recovering the product by distillation. The dialkyl carbonate yields of such processes are about 90% or higher.

Ball and others in â € œAngewandte Chemie International Edition in Englishâ € (1980), Vol. 19, pg. 718, report that the alkyl carbamate formation stage can be carried out at a relatively low temperature, between 100 ° C and 170 ° C, while the dialkyl carbonate production stage can be carried out at a temperature between 180 ° C and 270 ° C. Both stages are conveniently carried out by removing the reaction ammonia, in the presence of a bifunctional catalytic system, consisting of a Lewis acid, such as diisobutyl aluminum hydride, and a Lewis base, such as triphenylphosphine, which allows to reduce the formation of by-products deriving from the decomposition of alkyl carbamate.

In the American patent application US 2005/0203307 a synthesis process of dialkylcarbonates from urea and alcohol is described, characterized in that, in a pre-reactor, in the absence of catalyst, at a temperature between 120 ° C and 180 ° C and at a pressure between 0.2 MPa and 2 MPa, the water present as impurity of the reactants is removed and the alkyl carbamate is partially or completely formed. The production of dialkyl carbonate instead takes place in a reactor equipped with a distillation column, in the presence of at least one tin (IV) alkoxide such as, for example, dibutyltin dimethoxide and at least one high-boiling solvent containing electron donor atoms such as, for example, triglime ( triethylene glycol dimethyl ether). The reaction is carried out at a temperature of about 180 ° C and at a pressure of about 0.6 MPa, by feeding the urea-alkyl carbamate in alcohol mixture from the pre-reactor to the reactor and removing the dialkyl carbonate from the head. The selectivity to dialkyl carbonate reported for this process is about 91% -93%.

The aforementioned synthesis process of diethyl carbonate from bioethanol and urea can also be carried out in the presence of heterogeneous catalysts such as, for example, metal oxides, which are less toxic than the organo-tin compounds. For example Wang et al in â € œFuel Processing Technologyâ € (2007), Vol. 88, pg. 807, report that among the tested oxides, zinc oxide is the one that showed the best catalytic activity, even if the yields of diethyl carbonate obtained are decidedly lower than those of the previously described processes.

In accordance with a further preferred embodiment of the present invention, said diethyl carbonate can be obtained by means of a process which comprises the oxidative carbonylation of bioethanol with carbon monoxide and oxygen, in the presence of at least one catalyst. Said process is preferably carried out in the gas phase using heterogeneous catalysts, such as for example CuCl2 / PdCl2 / AC, containing copper (II) chloride and palladium (II) chloride supported on activated carbon (AC); or CuCl2 / PdCl2 / AC-KOH, obtained from the previous catalyst by subsequent treatment with potassium hydroxide; or CuCl2 / PdCl2 / KCl / AC-NaOH, obtained by impregnating activated carbon with CuCl2, PdCl2, KCl and subsequent treatment with sodium hydroxide.

More details on this ethanol oxidative carbonylation process are described, for example, by Yanji and others in â € œApplied Catalysis A: Generalâ € (1998), Vol. 171, p. 255; by Dunn et al in â € œEnergy & Fuelsâ € (2002), Vol. 16, pg. 177; by Zhang et al in â € œJournal of Molecular Catalysis A: Chemicalâ € (2007), Vol. 266, pg. 202.

Said bioethanol can be obtained through fermentation processes from biomass, or from various agricultural products rich in carbohydrates and sugars such as, for example, cereals, sugar crops, starchy, pomace, or their mixtures, known in the art.

In accordance with a preferred embodiment of the present invention, said bioethanol can be obtained by fermentation of at least one biomass deriving from agricultural crops such as, for example, corn, sorghum, barley, beet, sugar cane, or mixtures thereof.

In accordance with a further preferred embodiment of the present invention, said bioethanol can be obtained by fermentation of at least one lignocellulosic biomass which can be chosen among:

- products of crops specifically cultivated for energy use (for example, miscanthus, panic, rod, common reed), including waste, residues and waste from these crops or their processing;

- products of agricultural crops, forestry and forestry, including wood, plants, residues and waste from agricultural processing, forestry and forestry;

- waste from agro-food products intended for human consumption or zootechnics;

- the residues, not chemically treated, from the paper industry;

- waste from the separate collection of municipal solid waste (e.g. urban waste of vegetable origin, paper, etc.);

or their mixtures.

Said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] can be obtained through various procedures known in the art. For example, as mentioned above, said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] can be obtained by hydrogenation / deoxygenation of a material deriving from renewable sources such as, for example, soybean oil, rapeseed oil, corn, sunflower oil, including triglycerides and free fatty acids, in the presence of hydrogen and a catalyst as described, for example, by Holmgren J. and others in the article â € œNew developments in renewable fuels offer more choicesâ €, published in â € œHydrocarbon Processingâ €, September 2007, pg. 67-71.

It is known that, in order to improve the cold behavior characteristics of hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)], the product obtained from the aforementioned hydrogenation / deoxygenation, suitably purified, can be subjected to a hydrogenation / isomerization process, which transforms a part of the n-paraffins present in said product into isoparaffins, as described, for example, in the European patent application 1,728,844 and in the international patent application WO 2008/058664.

For the purpose of the present invention, any hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] can be used.

According to a preferred embodiment of the present invention, said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] can have a density, at 15 ° C, determined according to EN ISO 3675: 1998, between 720 kg / m <3> and 820 kg / m <3>, preferably between 750 kg / m <3> and 800 kg / m <3>.

According to a preferred embodiment of the present invention, said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] can have a flash point, determined according to EN ISO 2719: 2002, greater than or equal to 55 ° C, preferably greater than or equal to 65 ° C.

The composition of gas oil object of the present invention can optionally comprise methyl esters of fatty acids (FAME) in a quantity lower than or equal to 10% by volume, preferably lower than or equal to 7% by volume, with respect to the total volume of said composition taken equal to 100.

The composition of diesel fuel object of the present invention may possibly include conventional additives known in the art such as, for example, â € œflow improversâ €, â € œlubricity improversâ €, â € œcetane improversâ €, antifoam, detergents, antioxidants, anticorrosives, additives antistatic agents, dyes, or mixtures thereof. Generally, if present, said additives are present in quantities not exceeding 0.3% by volume with respect to the total volume of said composition taken equal to 100.

In order to better understand the present invention and to put it into practice, some illustrative and non-limiting examples thereof are reported below.

EXAMPLE 1

Synthesis of diethyl carbonate (BioDEC) by transesterification of dimethyl carbonate (DMC) with bioethanol.

The equipment that was used for the preparation of diethyl carbonate (BioDEC) consisted of a jacketed glass flask, with a volume of 2 liters, heated by circulation in the oil jacket coming from a thermostatic bath, equipped with a magnetic stirrer, thermometer and a glass distillation column with 30 perforated plates. In the head of the column all the vapor is condensed and only a part of the liquid is withdrawn through the intervention of an electromagnetic valve.

The following reagents were added to the aforementioned glass flask in an inert atmosphere: 1081 g (12 moles) of dimethyl carbonate (purity equal to 99.9%), containing 200 mg / kg of water and 0.1% by weight of methanol; 1106 g (23.9 moles) of anhydrous bioethanol (purity equal to 99.6%) for automotive, compliant with EN 15376: 2008, containing 1000 mg / kg of water, 0.1% by weight of methanol and 0, 2% by weight of C3-C5 saturated alcohols; 8.6 g of a 30% by weight solution of sodium methoxide in methanol.

The reaction mixture was kept under stirring, at atmospheric pressure, and heated to boiling. When the head temperature of the column stabilized at a value of 63.5 ° C, the distillate containing the azeotrope methanol-dimethyl carbonate was taken, operating with a reflux ratio such as to maintain the constant the temperature of the head as much as possible, thus minimizing the content of ethanol in the distillate.

In this first phase of the reaction, lasting about 5 hours (column head temperature: 63.5 ° C - 64.5 ° C), a quantity of distillate equal to 580.5 g was collected, characterized by the following composition , determined by gas chromatographic analysis:

- 69.5% by weight of methanol;

- 30.0% by weight of dimethyl carbonate;

- 0.5% by weight of ethanol.

In the second phase of the reaction, the reaction mixture remaining in the glass flask, after the removal by distillation of the azeotrope methanol-dimethyl carbonate formed during said first reaction phase, was heated until boiling, to atmospheric pressure, obtaining the transformation of most of the methyl-ethyl carbonate to diethyl carbonate (BioDEC) by reaction with bioethanol and the formation of methanol which was removed by distillation. In said second reaction phase, lasting about 13 hours (column head temperature: 64.5 ° C - 124 ° C), a quantity of distillate equal to 784.1 g was collected, characterized by the following composition, determined by gas chromatographic analysis:

- 19.5% by weight of methanol;

- 39.9% by weight of ethanol;

- 7.4% by weight of dimethyl carbonate;

- 23.4% by weight of methyl-ethyl carbonate;

- 9.8% by weight of diethyl carbonate (BioDEC).

The reaction mixture remaining in the glass flask, containing mainly diethyl carbonate, was subjected to distillation, operating at atmospheric pressure. At the end of the distillation (about 1 hour), 768 g of distillate were collected, characterized by the following composition, determined by gas chromatography analysis:

- 99.5% by weight of diethyl carbonate (BioDEC);

- 0.5% by weight of methyl-ethyl carbonate.

The distillation residue was subjected to filtration to remove the catalyst, obtaining 61 g of product, mainly containing diethyl carbonate (BioDEC) (95.8% by weight) and dialkyl carbonates from C3-C5 alcohols (4.2% in weight).

The synthesis of diethyl carbonate (BioDEC), carried out as described above, is characterized by a conversion of dimethyl carbonate equal to 78.5%, by a conversion of bioethanol equal to 71.3%, by a selectivity of dimethyl carbonate to diethyl carbonate (BioDEC) equal to 80.7% and a selectivity of dimethyl carbonate to methyl-ethyl carbonate equal to 19.1%.

The diethyl carbonate (BioDEC) obtained has a purity of 99.5%.

EXAMPLE 2 (comparative)

To a diesel having the characteristics shown in Table 1, a hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] has been added with the characteristics shown in Table 2, in a quantity equal to 45% by volume with respect to the total volume of the composition consisting of gas oil and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)]: the characteristics of the composition obtained are shown in Table 3.

TABLE 1

CHARACTERISTICS OF THE DIESEL STANDARD AS IS

Density at 15 ° C EN ISO 3675: 1998 844 (kg / m <3>)

Flash point EN ISO 2719: 2002 69

(° C)

Cetane number EN ISO 5165: 1998 52

Distillation ASTM D86-09e1

(° C)

IBP 173

50% vol. 272

95% vol. 352

FBP 367

Total flavorings EN 12916: 2006 29

(wt%)

Sulfur EN ISO 20846: 2004 7 (mg / kg)

CP <(*)> EN 23015: 1994 -3

(° C)

CFPP <(**)> EN 116: 1997 -6

(° C)

<(*)>: cloud point (â € œcloud pointâ €);

<(**)>: filter clogging point (â € œcold filter plugging pointâ €).

TABLE 2

CHARACTERISTICS NORMA HYDRO-TREATED VEGETABLE OIL AS IT IS

Density at 15 ° C EN ISO 3675: 1998 779 (kg / m <3>)

Flash point EN ISO 2719: 2002 78

(° C)

Cetane number EN ISO 5165: 1998 77

Distillation ASTM D86-09e1

(° C)

IBP 188

50% vol. 285

95% vol. 299

FBP 311

Total flavorings EN 12916: 2006 0

(wt%)

Sulfur EN ISO 20846: 2004 <3 (mg / kg)

CP <(*)> EN 23015: 1994 1

(° C)

CFPP <(**)> EN 116: 1997 -1

(° C)

<(*)>: cloud point (â € œcloud pointâ €);

<(**)>: filter clogging point (â € œcold filter plugging pointâ €).

TABLE 3

CHARACTERISTICS STANDARD DIESEL COMPOSITION HYDRO-TREATED VEGETABLE OIL

Density at 15 ° C EN ISO 3675: 1998 815 (kg / m <3>)

Flash point EN ISO 2719: 2002 74

(° C)

Cetane number EN ISO 5165: 1998 60

Distillation ASTM D86-09e1

(° C)

IBP 185

50% vol. 276

95% vol. 332

FBP 352

Total flavorings EN 12916: 2006 17.4

(wt%)

Sulfur EN ISO 20846: 2004 5 (mg / kg)

CP <(*)> EN 23015: 1994 -8

(° C)

CFPP <(**)> EN 116: 1997 -12

(° C)

<(*)>: cloud point (â € œcloud pointâ €);

<(**)>: filter clogging point (â € œcold filter plugging pointâ €).

From the data reported in Table 3 it is clear that the addition of vegetable oil

hydrotreated [â € œhydrotreated vegetable oil (HVO)] in high quantities affects

negatively on the characteristics of the starting diesel, in particular, for

as regards the density which is lower than the specification limit set by the EN 590: 2009 standard.

EXAMPLE 3 (invention)

A hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] with the characteristics shown in Table 2, in a quantity equal to 45% by volume and diethyl carbonate ( BioDEC) (purity equal to 99.5%) obtained according to Example 1 above, in a quantity equal to 4% by volume, said quantities having been calculated with respect to the total volume of the composition consisting of gas oil, hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] and diethyl carbonate: the characteristics of the composition obtained are shown in Table 4.

TABLE 4

CHARACTERISTICS STANDARD DIESEL COMPOSITION HYDRO-TREATED VEGETABLE OIL BioDEC Density at 15 ° C EN ISO 3675: 1998 821 (kg / m <3>)

Flash point EN ISO 2719: 2002 55

(° C)

Cetane number EN ISO 5165: 1998 59

Distillation ASTM D86-09e1

(° C)

IBP 135

50% vol. 274

95% vol. 331

FBP 352

Total flavorings EN 12916: 2006 16,7

(wt%)

Sulfur EN ISO 20846: 2004 4 (mg / kg)

CP <(*)> EN 23015: 1994 -8

(° C)

CFPP <(**)> EN 116: 1997 -12

(° C)

<(*)>: cloud point (â € œcloud pointâ €);

<(**)>: filter clogging point (â € œcold filter plugging pointâ €).

From the data reported in Table 4 it can be seen that the addition of diethyl carbonate

(BioDEC) obtained from bioethanol, improves the properties of the composition

consisting of diesel and hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ €

(HVO)] as regards the density which is thus within the specification limits set by the EN 590: 2009 standard. Furthermore, the addition of diethyl carbonate (BioDEC) obtained from bioethanol does not negatively affect the other characteristics of said composition, in particular, as regards flammability, cetane number, cold properties such as cloud point [â € œcloud pointâ € (CP)] and filter clogging point [â € œcold filter plugging pointâ € (CFPP)].

Claims (23)

CLAIMS 1. Composition of diesel fuel comprising: - from 5% by volume to 79.9% by volume with respect to the total volume of said composition of at least one diesel oil; - from 0.1% by volume to 20% by volume with respect to the total volume of said composition of at least one diethyl carbonate; - from 20% by volume to 75% by volume with respect to the total volume of said composition of at least one hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)]; wherein said diethyl carbonate is obtained from bioethanol. Gas oil composition according to claim 1, wherein said composition comprises from 30% by volume to 68% by volume with respect to the total volume of said composition of at least one gas oil. Gas oil composition according to claim 1 or 2, wherein said composition comprises from 2% by volume to 10% by volume with respect to the total volume of said composition of at least one diethyl carbonate. 4. Composition according to any one of the preceding claims, wherein said composition comprises from 30% by volume to 60% by volume with respect to the total volume of said composition of at least one hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)]. 5. Composition according to any one of the preceding claims, wherein said gas oil has a density, at 15 ° C, determined according to EN ISO 3675: 1998, between 800 kg / m <3> and 870 kg / m <3> . 6. Composition according to claim 5, wherein said gas oil has a density, at 15 ° C, determined according to EN ISO 3675: 1998, between 820 kg / m <3> and 850 kg / m <3>. 7. Composition according to any one of the preceding claims, wherein said gas oil has a flash point, determined according to EN ISO 2719: 2002, greater than or equal to 55 ° C. 8. Composition according to claim 7, wherein said gas oil has a flash point, determined according to EN ISO 2719: 2002, greater than or equal to 65 ° C. 9. Composition according to any one of the preceding claims, wherein said gas oil has a cetane number, determined according to EN ISO 5165: 1998, greater than or equal to 49. 10. Composition according to claim 9, wherein said gas oil has a cetane number, determined according to EN ISO 5165: 1998, greater than or equal to 51. Gas oil composition according to any one of the preceding claims, wherein said diethyl carbonate is obtained by means of a process which comprises the transesterification of at least one dialkyl carbonate, or of at least one cyclic carbonate, with bioethanol, in the presence of at least one catalyst. 12. Gas oil composition according to any one of claims 1 to 10, wherein said diethyl carbonate is obtained by a process which comprises the reaction of urea with bioethanol, in the presence of at least one catalyst. 13. Gas oil composition according to any one of claims 1 to 10, wherein said diethyl carbonate is obtained by a process which comprises the oxidative carbonylation of bioethanol with carbon monoxide and oxygen, in the presence of at least one catalyst. 14. Gas oil composition according to any one of the preceding claims, wherein said bioethanol is obtained by fermentation of at least one biomass deriving from agricultural crops such as corn, sorghum, barley, beet, sugar cane, or their mixtures. Gas oil composition according to any one of claims 1 to 13, wherein said bioethanol is obtained by fermentation of at least one lignocellulosic biomass is chosen from: - products of crops specifically cultivated for energy use (such as miscanthus, panic, rod, common reed), including waste, residues and waste from these crops or their processing; - products of agricultural crops, forestry and forestry, including wood, plants, residues and waste from agricultural processing, forestry and forestry; - waste from agro-food products intended for human consumption or zootechnics; - the residues, not chemically treated, from the paper industry; - waste from the separate collection of solid urban waste (such as urban waste of vegetable origin, paper); or their mixtures. 16. Composition of gas oil according to any one of the preceding claims, wherein said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] has a density, at 15 ° C, determined according to EN ISO 3675: 1998, between 720 kg / m <3> and 820 kg / m <3>. 17. Composition of gas oil according to claim 16, wherein said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] has a density, at 15 ° C, determined according to EN ISO 3675: 1998, between 750 kg / m <3> and 800 kg / m <3>. 18. Composition of gas oil according to any one of the preceding claims, wherein said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] has a flash point, determined according to EN ISO 2719: 2002, greater than or equal to 55 ° C. 19. Composition of gas oil according to claim 18, wherein said hydrotreated vegetable oil [â € œhydrotreated vegetable oilâ € (HVO)] has a flash point, determined according to EN ISO 2719: 2002, greater than or equal to 65 ° C . Composition of gas oil according to any one of the preceding claims, wherein said composition comprises methyl esters of fatty acids (FAME) in a quantity lower than or equal to 10% by volume with respect to the total volume of said composition taken equal to 100. 21. Gas oil composition according to claim 20, wherein said composition comprises methyl esters of fatty acids (FAME) in an amount lower than or equal to 7% by volume with respect to the total volume of said composition taken equal to 100. 22. Gas oil composition according to any one of the preceding claims, wherein said composition comprises additives such as â € œflow improversâ €, â € œlubricity improversâ €, â € œcetane improversâ €, antifoamers, detergents, antioxidants, anticorrosives, antistatic additives, dyes, in quantities not exceeding 0.3% by volume with respect to the total volume of said composition taken equal to 100. 23. Use of the composition of any one of claims 1 to 22, as a fuel for diesel engines.