BG64828B1 - Method for producing fuel mixture from diesel fuel - Google Patents

Abstract

The method can be used in the petrochemical industry. It improves the operational and ecological characteristics of the fuel mixture. By the method, to the diesel fuel esters of the fatty acids with lower alcohols are added, producing the re-esterification of vegetable oils with lower alcohols, in the presence of a catalyst of alkali metal hydroxide, after which the produced esters are purified.To the diesel fuel with sulphur content under 0.3 wt. %, esters of the fatty acids with lower alcohols from 5 to 40 wt. % are added without agitation, heated to 30-50 degrees C. The re-esterification of the vegetable oil is made with lower monovalent alcohol from 20 to 30 vol. % at 50-70 degrees C at atmospheric pressure, in the presence of a catalyst of alkali metal hydroxide from 0.6 to 0.9 wt.%. The use of refined sunflower oil is preferable, and a mixture of freshly refined and used vegetable oil can also be used in ratio up to 1:1.

Description

The invention relates to a method for producing a diesel fuel mixture which is used in the refining industry.

BACKGROUND OF THE INVENTION

It is known that when diesel is burned, sulfur oxides are emitted into the atmosphere by internal combustion engines which pollute the environment. Therefore, the sulfur content of diesel is limited to 0.05 - 0.3 wt. %. On the other hand, the low sulfur content of the diesel fuel impairs its lubricating properties, which results in faster wear of the diesel engine's fuel system.

EP 0 860 494 discloses a method for preparing a fuel mixture in which, in order to improve the lubricating properties of diesel fuel with a sulfur content of less than 0.5% by weight. 0.02 to 0.5% by weight are added. fatty acid esters obtained by transesterification of genetically modified lower alcohol oils.

BPO 635558 describes a method using a mixture of diesel fuel with a sulfur content of less than 0.2% by weight. and a mixture of fatty acid methyl esters contained in vegetable oils (Biodiesel). The biodiesel concentration in the cited mixture is from 100 - 10000 ppm (0.01 - 1% by weight) in order to improve the lubricating properties. The patent proposes a method of producing a concentrated additive for basic diesel fuel consisting of a mixture of diesel fuel with Biodiesel up to 50% by weight.

EP 0 608 149 describes a method in which a diesel fuel additive consisting of methyl esters of acids contained in vegetable oils is used to reduce the fuel consumption of the engine. The concentration of the additive is from 0.0001 to 0.2% by weight. The patent describes a process for the preparation of a concentrated additive for a basic diesel fuel consisting of a liquid carrier (paraffins, isoparaffins, alcohols, etc.) and methyl esters of up to 75% by weight. The liquid carrier must be compatible with both the base fuel and the additive. Using a liquid carrier to mix the additive with the base fuel complicates the process.

All three patents propose the use of methyl esters as additives to low-sulfur base diesel at low concentrations to improve the lubricating properties of the fuel. Low concentrations of the additive do not lead to a reduction in the sulfur content of diesel fuels.

There is also a method of preparing fatty acid esters of lower monovalent alcohols by transesterification of glycerides of fatty acid with lower monovalent alcohols in the presence of an alkali metal or alkaline earth metal hydroxide catalyst in an amount of 1.38-2.5% by weight. After the glycerol phase is separated, the resulting esters are subjected to purification from the catalyst residues by treatment with water or dilute organic or inorganic acid. The esters obtained are used as an adjunct to diesel fuels, lubricants and more. (BG 61163).

The disadvantages of the method are the use of large amounts of catalyst and of freshly refined and / or genetically modified oils.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method for producing a diesel fuel mixture that provides a reduced sulfur content of the fuel at high lubricating properties of the fuel mixture.

The method for the preparation of the fuel mixture involves the transesterification of low-alcohol vegetable oils in the presence of an alkali metal hydroxide catalyst, the subsequent purification of the obtained esters from the catalyst and the mixing of the esterification at atmospheric pressure with diesel fuel with a sulfur content below 0.3% . According to the invention, during the transesterification, the amount of alcohol is from 20 to 30% by volume. relative to the amount of vegetable oils, the amount of catalyst is from 0.6 to 0.9% by weight. and the transesterification temperature is 50-70 ° C. The mixing was carried out as the pre-esterifier heated to a temperature of 30-5 ° C and in an amount of 5 to 40% vol. relative to the total amount of blend, is added to the diesel without stirring.

The use of refined sunflower oil is preferred.

According to the invention, a mixture of freshly refined and used vegetable oil in a ratio of up to 1: 1 may also be used.

The lower monovalent alcohol is preferably ethyl or methyl alcohol.

The transesterification of the vegetable oil is carried out for up to 8 hours, during the initial 30-40 min the process is carried out with constant stirring with a mass exchange of 400 min ¹ .

Purification of the resulting esters from the catalyst is carried out by washing with water or inorganic acid solution with a pH of up to 10% vol. of the volume of the esters, the washing being repeated to pH 5-6 of the methyl esters and then warming to 60-70 ° C.

The fuel mixture according to the invention is a diesel fuel containing up to 40% by weight. fatty acid esters obtained from the transesterification of lower alcohol alcohols in the presence of a catalyst.

The advantages of the process and the product obtained according to the invention are expressed in the following. Due to the large difference in viscosity and density of diesel fuel and fatty acid esters, the latter are heated to a temperature of 30-50 ° C, ie. to equalize the kinematic viscosities of the two products. This ensures a good homogenization of the resulting fuel mixture without stirring and the use of higher fatty acid esters with lower alcohols, which in turn results in a reduction in the sulfur content of the resulting fuel mixture and better lubricating properties of the mixture. As a result, an increase in the performance and environmental performance of the fuel mixture is ensured. The amount of catalyst in the transesterification of vegetable oils is lower than the known methods, which results in the saving of reagents and easier purification of the esters obtained from the catalyst residues. The method is applicable both to freshly refined vegetable oils and to the use of mixtures including used oils.

Examples of carrying out the invention

Example 1.

In a 2000 cm ³ container mix 500 cm ^{3 of} fresh refined sunflower oil and 500 cm ^{3 of} used sunflower oil (filtered through a paper filter at room temperature). The resulting fat was heated to 70 ° C. 230 cm ^{3 of} methyl alcohol (98% pure for analysis) and 8.2 g of NaOH (crystalline) are mixed in a separate container with a capacity of 500 cm ³ . The sodium hydroxide solution is added to the methyl alcohol by stirring until completely dissolved. The resulting sodium methylate is added to the heated fat by stirring. The conversion process is carried out with continuous agitation with an electric stirrer. After 30 minutes, the stirring was stopped. Separation occurs within 20 min, and the complete reaction takes 8 h.

The two phases are clearly distinguishable - the upper oil portion is yellow and the lower glycerin is dark brown. The quantitative phases are 980 cm ³ top layer and 250 cm ³ bottom layer. The glycerol phase was drained and the oil was washed by stirring and adding 100 cm ^{3 of} water. The water was allowed to decant and then drained. The procedure was repeated to pH 6 of the methyl esters obtained and then heated to 60 ° C. The fatty acid methyl esters obtained have the characteristics as fuel specified in Table 1.

Table 1

Indicators Value Cetane index 45 Fract. Ingredients: 50% distillate at t 290 90% distillate at t 350 95% distillate at t 378 Kinematic viscosity at 40 ^U C, mm ² / sec 4.0 Sulfur content, wt. % <0.01 Flash point in closed crucible, ° C 100 Filtering limit, ° C -9 Actual resin content, mg / 100cm ⁵ 140 Combustion heat, KJ / kg 38200 Relative density, g / cm ³ 0.89

900 cm ^{3 of} diesel with the indicators given in Table 2 is mixed with 100 cm of the methyl esters obtained heated to 50 ° C. The fuel produced has the indicators listed in Table 3.

Table 2

Indicators Value Cetane index 49 Fract. Ingredients: 50% distillate at t 248 90% distillate at t 326 95% distillate at t 343 Kinematic viscosity at 40 ^U C, mm ^ / sec 2.2 Sulfur content, wt% 0.24 Flash point in closed crucible, ° C 63 Filtering limit, ° C -20 Actual resin content, mg / 100cm ³ 25 Combustion heat, KJ / kg 42900 Relative density, g / cm 0.84

Table 3

Indicators Value Cetane index 49 Fract. Ingredients: 50% distillate at t 268 90% distillate at t 338 95% distillate at t 345 Kinematic viscosity at 40 C, mm / sec 2.63 Sulfur content, wt% 0.22 Flash point in a closed crucible, ^b C. 68 Filtering limit, ° C -12 Actual resin content, mg / 100cm ³ 37 Combustion heat, KJ / kg 42800 Relative density, g / cm ³ 0.847

Lubricating properties: Improvement - 19% higher kinematic viscosity.

Sulfur content decreased by 8.3%.

The measured amount of SO ₂ emitted during combustion of 100 g of fuel is 168 cm ³ .

Fuel Performance: Complies with DIN, ISO, BDS standards.

Example 2.

By the method described in Example 1, 1000 cm ^{3 of} fresh refined sunflower oil is processed. The amount of catalyst

KOH is 5.52 g. The alcohol is ethanol and is 230 cm ³ . Ethylation was obtained by heating to 30 ° C. After the glycerol is separated from the oily phase, the latter is washed with a solution of H ₂ SO ₄ to pH 4. The amount of the single-wash solution is 98 cm ³ . The number of washes is determined by the pH value of the oily phase, keeping this value at least 5. The resulting product is heated to 60 ° C. The characteristics of the ethyl esters obtained are given in Table 4.

Table 4.

Table 4

Indicators Value Cetane index 45 Fract. Ingredients: 50% distillate at t 285 90% distillate at t 348

95% distillate at t 360 Kinematic viscosity at 40 C, mm / sec 3.5 Sulfur content, wt% <0.01 Flash point in closed crucible, ° C 100 Filterability limit, ^and C -9 Actual resin content, mg / 100cm ³ 106 Combustion heat, KJ / kg 38200 Relative density, g / cm ³ 0.87

700 cm ^{3 of the} diesel fuel with the indicators given in Example 1, Table 2, is mixed with 300 cm ³ of the resulting ethyl esters heated to 50 ° C. The fuel produced has the indicators listed in Table 5.

Table 5

Indicators Value Cetane index 47 Fract. composition: 286 50% distillate at t 90% distillate at t 330 95% distillate at t 340 Kinematic viscosity at 40 ^U C, mm ² / sec 2.85 Sulfur content, t% 0.15 Flash point in closed crucible, ° C 65 Filterability limit, ^and C -12 Actual resin content, mg / 100cm ³ 49.3 Combustion heat, KJ / kg 42670 Relative density, g / cm ³ 0.85

Lubricating properties: improved - 29% higher kinematic viscosity.

The sulfur content is reduced by 16%.

The measured amount of SO ₂ emitted during combustion of 100 g of fuel is 105 cm ³ .

Fuel Performance: Complies with DIN, ISO, BDS standards.

Example 3.

800 cm ^{3 of} diesel fuel with the indicators given in Example 1, Table 2, is mixed with 200 cm ^{3 of} methyl esters heated to 50 ° C obtained by the method described in the same example. The fuel obtained has the following indicators (Table 6).

Table 6

Indicators Value Cetane index 48 Fract. composition: 50% distillate at t 270 90% distillate at t 335 95% distillate at t 342 Kinematic viscosity at 40 ° C, mm ² / sec 2.77 Sulfur content, wt. % 0.20 Flash point in closed crucible, ° C 65 Filterability limit, ^and C -12 Actual resin content, mg / 100 cm ³ 49 Combustion heat, KJ / kg 42730 Relative density, g / cm ³ 0.849

Lubricating properties: Improvement - 25% higher kinematic viscosity.

The sulfur content is reduced by 16%.

The measured amount of 25 SO ₂ emitted during combustion of 100 g of fuel is 140 cm ³ .

Fuel Performance: Complies with DIN, ISO, BDS standards.

Example 4.

700 cm ³ of diesel fuel with parameters specified in Example 1, Table 2, was mixed with 300 cm @ ^3, heated to 50 ° C methyl esters obtained by the method described in Example 2. The resultant fuel has the following parameters (Table 7).

Table 7

Indicators Value Cetane index 47 Fract. composition: 286 50% distillate at t 90% distillate at t 330 95% distillate at t 340 Kinematic viscosity at 40 ^U C, mm ² / sec 2.85 Sulfur content, wt% 0.15 Flash point in a closed crucible, ^and C 65 Filtering limit, ° C -12 Actual resin content, mg / 100cm ³ 49.3 Combustion heat, KJ / kg 42670 Relative density, g / cm ³ 0.85

Lubricating properties: improved - 29% higher kinematic viscosity.

The sulfur content is reduced by 16%.

The measured amount of SO ₂ emitted during combustion of 100 g of fuel is 105 cm ³ .

Fuel performance meets DIN, ISO, BDS standards.

Example 5.

In the method described in Example 1, 1000 cm ^{3 of} fresh refined sunflower oil is processed, the catalyst being NaOH in the amount of 7.36 g, the alcohol being ethanol - 250 cm ³ . The transesterification was carried out at 60 ° C.

600 cm ^{3 of} diesel with the indicators given in Example 1, Table 2, is mixed with 400 cm ³ of the resulting ethyl esters heated to 40 ° C. Lubricating properties: Improve 35% higher kinematic viscosity. The sulfur content is reduced by 25%.

Fuel Performance: Complies with DIN, ISO, BDS standards.

Example 6

In the method described in Example 1, 1000 cm ^{3 of} fresh refined sunflower oil is processed, the catalyst being NaOH in the amount of 6.44 g, the alcohol being ethanol - 270 cm ³ . The transesterification was carried out at 50 ° C.

950 cm ^{3 of} diesel with the indicators given in Example 1, Table 2, is mixed with 50 cm ³ of the resulting ethyl esters heated to 30 ° C. Lubricating properties: improved - 8% higher kinematic viscosity. The sulfur content is reduced by 4%.

Fuel Performance: Complies with DIN, ISO, BDS standards.

Example 7.

In the method described in Example 1, 600 cm ^{3 of} fresh refined sunflower oil and 400 cm ^{3 of} used sunflower oil were processed, the catalyst being NaOH in the amount of 7.82 g, the alcohol being methanol - 300 cm ³ . The transesterification was carried out at 50 ° C.

650 cm ^{3 of} diesel with the indicators given in Example 1, Table 2, is mixed with 350 cm ³ of the resulting ethyl esters heated to 40 ° C.

Lubricating properties: Improved - 30% higher kinematic viscosity. The sulfur content is reduced by 19%.

Fuel Performance: Complies with DIN, ISO, BDS standards.

Example 8.

In the method described in Example 1, 600 cm ^{3 of} fresh refined sunflower oil and 400 cm ^{3 of} used sunflower oil were processed, the catalyst being NaOH in an amount of 8.28 g, the alcohol being methanol 200 cm ³ . The transesterification was carried out at 70 ° C.

600 cm ^{3 of} diesel with the indicators given in Example 1, Table 2, is mixed with 400 cm ³ of the resulting ethyl esters heated to 40 ° C. Lubricating properties: Improved 38% higher kinematic viscosity. The sulfur content is reduced by 25%.

Fuel Performance: Complies with DIN, ISO, BDS standards.

Claims

Claims (7)

1. A method for the preparation of a diesel fuel mixture comprising the transesterification of vegetable oils with lower alcohols in the presence of a catalyst consisting of an alkali metal hydroxide, the subsequent purification of the obtained esters from the catalyst and the mixing of the esterification at atmospheric pressure with diesel fuel of sulfur less than 0.3% by weight, characterized in that during the transesterification, the amount of alcohol is from 20 to 30% by volume. relative to the amount of vegetable oils, the amount of catalyst is 0.6 to 0.9% by weight. and the temperature of the esterification is 50-70 ° C, and during the mixing the pre-esterification is heated to a temperature of 3050 ° C and is in an amount of 5 to 40% vol. by the total amount of mixture. 2. The method according to claim 1, wherein the vegetable oil is refined sunflower oil. Method according to claim 2, characterized in that a mixture of fresh refined and used sunflower oil is used in a ratio of up to 1: 1. 4. The method of claim 1, wherein the lower monovalent alcohol is ethyl or methyl alcohol. 5. The method according to claim 1, characterized in that the transesterification of the vegetable oil is carried out for a period of up to 8 hours, and in the initial 30-40 minutes the process is carried out with constant stirring with a mass-5 exchange ratio of 400 min ¹ . Method according to claim 1, characterized in that the purification of the obtained esters from the catalyst is carried out by washing with water or inorganic acid solution with pH 4 in an amount up to 10% vol. of the volumetric amount of the esters, the washing being repeated to pH 5-6 of the methyl esters, after which they are heated to 6070 ° C. 7. Diesel fuel mixture prepared by the method of claim 1, comprising from 5 to 40% by weight. fatty acid esters obtained from the transesterification of lower alcohol alcohols in the presence of a catalyst. Publication of the Patent Office of the Republic of Bulgaria 1113 Sofia, 52-B Dr. GM Dimitrov Blvd.