The present invention relates to diesel fuels, and can be used in the national economy as a motor fuel, equivalent by its physical and chemical characteristics to the petroleum motor fuel. State of the art

The currently used fuels for diesel engines mainly contain components of crude oil. There is a need for high-quality fuel composition for diesel engines, containing components of biological origin, which also meets the requirements for the quality of diesel fuels operating at any temperature. Moreover, the fuel must be environmentally sound. Currently, the most common component of biological origin in fuels is the rapeseed methyl ether, designated as RME (RU 2393209). RME is used either as such or in mixtures with other fuels. The disadvantages of RME are its poor miscibility with diesel fuels, and in comparison with conventional diesel (EN 590), especially at low temperatures, its poor storage stability and poor performance at low temperatures. Moreover, it leads to engine fouling and increases emissions of nitrogen oxides (NOx). The ITR production has a by-product (glycerin), which can be a problem when producing a large amount of product. Similarly, may be made ethers of other vegetable oils and fatty acid methyl ethers, commonly known as FAME (fatty acid methyl ether). Such FAME can be used for the same applications as the rapeseed methyl ether, but they also have a negative impact on the quality of diesel fuel, particularly with respect to its performance at low temperatures, and in addition, their use in fuels increases emissions of oxides nitrogen. In some cases, FAME and RME cause higher emissions of particles and smoke formation when starting the cold engine.

The application WO 2001012581 describes a process for producing methyl ethers used as biodiesel, wherein the mixtures of fatty acids and triglycerides are etherified in one phase. In this method, there is formed a solution of fatty acids, triglycerides, alcohol, acid catalyst and common solvents at temperatures below the boiling point of the solution. The co-solvent is used in amounts providing a single phase; the solution is then kept for a sufficient time to provide an acid- catalyzed etherification of fatty acids. After this, the acid catalyst is neutralized, an alkaline catalyst is added for the transetherification of triglycerides and finally, the ethers are recovered from the solution. In this manner, a biofuel containing ethers is produced which has a glycerine content of at least 0.4 % by weight.

The disadvantage is the complexity, multi-stage process and the high cost of the products. It is known that in order to increase the cetane number, diesel fuels on the basis of petroleum fractions and gas condensate, comprise additives that are ignition dopes such as organic nitrates. (U.S. Patent 4,473,378, CIOL 1/22, 1984)

However, these additives do not ensure the improvement of the startability of summer diesel fuels at low temperatures. Besides, the exhaust contains large amounts of nitrogen oxides. The addition of oxygenates such as alcohols and simple ethers to the fuels has successfully been proven in practice.

WO 81/00721 describes the fuel mixture, modified by adding alcohols, water, simple ethers and a vegetable oil. The purpose of using these simple ethers of glycerin is to eliminate the hydrophilicity and to lower boiling point to the range in which the diagram of boiling of the fuel components lies, and to reduce the density while maintaining the cetane number.

The drawback of simple ethers of glycerol is that, when they are produced, there is formed a mixture containing 11% of tri-ether at most. The remaining amount accounts for mono- and di-ethers, which are partially soluble in the individual fuel components due to still present hydroxyl groups.

There is known a petroleum diesel fuel, which contains as an additive in % by weight: alkyl (C3-C18) nitrate 75-90, corrosion component 5-15, and hydrocarbon fraction boiling off in the range of 120-2700S, up to 100. (Patent RF 2355732). However, the diesel fuel includes expensive components, which increases the cost, and the multi-stage process increases the formation of nitrogen oxides.

The closest to the claimed invention is the work described in the article of I.S. Khusnutdinov et al. (Chemistry and Chemical Engineering, 2009, Volume 52, no. 11 , page 119) "Research 1.1 on diethoxy ethane, as a component of diesel fuel." In this document, the compositions 1.1 of diethoxyethane with diesel fuel and rapeseed oil have been studied, and their key performance indicators have been identified compared with the requirements of GOST 305-82 for diesel fuel.

The disadvantage of this solution is a low cetane number 1.1 of diethoxyethane and compositions based on it, not exceeding 46 points, which does not comply with the requirements of the new GOST R53605-2009 (EN 14214:2003).

The object of the invention is to provide a diesel fuel containing a bio-additive to the petroleum diesel fuel, having a high cetane number, which, along with the improved low-temperature properties and the startability of the diesel fuel, impedes the process of corrosion, is used without the renovation of the engine, and has the ecologically-sound exhaust while significantly reducing the cost due to the use of components, in particular additives, based on low-cost large-tonnage available products, provided by domestic natural resources, including renewable ones.

The technical result of the invention is to provide a high-quality diesel fuel with low cost and high yield of the product, corresponding to the current GOST, as well as a high technological effectiveness of production and a broad resource base.

The use of fuel composition leads to an increased efficiency of the combustion process during the engine operation, to an increased engine power and to a reduced engine acceleration time. In addition, this product can be used to reduce emissions from the engine, improving the fluidity in the cold and increasing the cetane number.

The said effect is achieved by that the biofuel composition is a mixture of a petroleum diesel fuel (98-60% by volume) and a biofuel (2-40% by volume), which, in turn, consists of dietilformal (1.1 diethoxymethane), (35-40 % by volume) and glycerides of unsaturated fatty acids (65-60% by volume). Any vegetable oil may be used as glycerides.

Summary of the invention

It is known that Diesel tested his engine using a vegetable oil. But the vegetable oil has a high viscosity, high pouring point, and for this reason, methyl ether oils are commonly used in the world. The share of oil transetherification process accounts for up to 30% of the cost and with that alkali are used and byproducts are formed.

When dietilformal and glycerides of unsaturated fatty acids are used together (simple mixing), 11 indicators of the European standard EN 14214 for biodiesel are improved. The dietilformal - biofuel can be easily obtained from bioethanol and biogas which are renewable energy sources, by applying the known methods of ethanol and formaldehyde condensation (Himik.ru. Chemical Encyclopedia) and the formaldehyde is obtained from the methane through the methanol (ru.wikipedia.org. Methanol, formaldehyde).

The use of dietilformal in a mixture with glycerides of unsaturated fatty acids, such as vegetable oils, in an amount of 35-40% by volume, allows obtaining a biofuel with a high cetane number, its characteristics complying with the Russian standard GOST R53605-2009, European standard EN 14214-2003 and U.S. standard ASTMD 6751. In so doing, this eliminates the need for the transetherification of oils with methanol, which accounts for 30% of costs and eliminates the need for disposal of by-products - glycerin and waste alkali catalyst

(Marketing research of the market of biofuel, ethanol and biodiesel, May 18, 2012 Research Techart, page 54). The better utilization of vegetable renewable raw materials is beneficial to the environment in general.

Table 1

An important parameter for the biodiesel is its shelf life, which it is very small and limited by high iodine number and by the quantity of unsaturated compounds in the oils. When the oils are diluted with dietilformal, the iodine number decreases and the biofuel becomes more resistant to the processes of oxidation, polymerization, etc.

The components were mixed at room temperature, and the analyses were carried out in a certified laboratory according to GOST. The methyl ethers of vegetable oils were obtained according to standard methods under comparable conditions.

The effect of DEP concentration mixed with vegetable oils, on the density, viscosity, and iodine value of the biodiesel compositions is shown in Table 1.

Table 2

Conclusions

1. With a concentration of dietilformal equal to 30 % by volume and a concentration of vegetable oils equal to 70% by volume, the indicators of viscosity do not meet the standard, but they are satisfactory on the iodine number and, excepting palm oil and linseed oil, they comply with the density indicator (0.900).

2. With a concentration of dietilformal equal to 35 % and a concentration of vegetable oils equal to 65%, all the indicators correspond to the American standard

ASTMD 6751, but in terms of viscosity (5.0), they do not correspond to EN 14214 - European standard and to the Russian GOST R53605-2009.

3. With a concentration of dietilformal equal to 40 % and a concentration of vegetable oils equal to 60%, all the indicators correspond to the international standards. Table 2 shows a comparison of the methyl ether, a mixture of DEP and of oil on the cetane number of the mixture of biodiesel and diesel fuel.

Conclusions

In our experiments a mixture of oil and dietilformal always has a cetane number which is slightly higher than that of the methyl ether of the given oil. The difference it is not significant, but this makes it possible to claim that the transetherification of oils with methanol is not economically feasible because the share of expenses accounts for 30% of the cost and moreover, some by-products are formed (glycerin and alkali) which should be disposed.