RU2365625C1 - Method of vegetable oil processing - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to method of obtaining ethers of fatty acids, which can be applied as biodiesel - alternative biofuel. Described is method of rapeseed oil processing by its re-etherification with ethyl alcohol, with separation of obtained products into fractions, obtained barbotage with carbon dioxin of immobilised granulated yeasts biomass, is realised in reactor at 350-400C and pressure 35-50 MPa with following cooling of mixture, oven control in extractor to 250C, extraction with carbon dioxide in overcritical conditions at 350C and pressure 35 MPa. Obtained homogenous mixture is supplied into first separator for separation of glycerin from target product, and then target product is supplied to second separator for separation of fatty acid ethyl ether from carbon dioxin, which is directed to recycling. ^ EFFECT: simplification of technological process and improvement of ecology due to application of overcritical ethyl alcohol, and obtaining of target product with conversion 95% and higher. ^ 2 cl, 2 ex

Description

The present invention relates to a method for producing fatty acid esters from fat and / or oil of biological origin by transesterification.

Biodiesel is an alternative environmentally friendly, relatively cheap diesel fuel produced from local plant materials. Biodiesel is obtained from vegetable oils (the cheapest is rapeseed) by transesterification reaction. The main reagents: vegetable oil and methanol with the addition of a small amount of catalyst - alkali (KOH). In known technological schemes for the production of biodiesel in cyclic plants using an alkaline catalyst, the reaction time reaches 8 hours. Such a long reaction time makes it impossible to create large-capacity plants and requires large production areas.

Biodiesel is an alternative biofuel of the 21st century. In the countries of the European Union, Russia, America, Ukraine, government programs have already been adopted to convert a significant part of the diesel fleet of cars to biodiesel. The use of biodiesel allows its consumers not to depend on world prices for oil and oil products, so biofuel is becoming more widespread throughout the world.

From a chemical point of view, biodiesel is a mixture of fatty acid esters. In its production, during the transesterification process, oils and fats react with methyl or ethyl alcohol in the presence of a catalyst (KOH, NaOH). A byproduct of the reaction is glycerin. Transesterification refers to the redistribution of acyl groups in fat triglycerides. Transesterification allows you to change the molecular (glyceride) composition of fat or a mixture of fats, without changing their fatty acid composition. A change in the glyceride composition of fat leads to a change in its physical properties (melting point, hardness, etc.). The mechanism of the transesterification reaction is the interaction of the carbonyl group of the C-O ester with the alcohol groups of di- and monoglycerides.

The main disadvantage of biodiesel production technology using a catalyst is the removal of catalyst and saponification products after the reaction, which is very important for the purity of the resulting product.

Biodiesel is a methyl (ethyl) esters obtained from vegetable oils through an esterification reaction: methanol (ethanol) is added to the vegetable oil in a ratio of approximately 9: 1 and a small amount of catalyst (alkaline or acid), after which the mixture is processed in a cavitation reactor. After the reaction is completed, biodiesel and technical glycerin are obtained. Both products have a high commodity value and a wide market. In addition, glycerin is an excellent high-calorie fuel for heating boilers.

There is a method of transesterification of fat and / or oil of biological origin by alcoholysis, which consists in preparing the transesterified fat and / or oil of biological origin in an appropriate container and then carrying out alcoholysis by adding monohydric alkanol and a catalyst to the prepared fat and / or oil, this as a catalyst using a metal salt of an amino acid or derivative of an amino acid insoluble in monatomic alkanols (RU 2263660 C2, 10.11.2005).

The disadvantage of this method is that the process is unreasonably delayed in time and also requires large reaction volumes, and it is also necessary to remove the catalyst upon completion of the reaction.

A known method for producing continuous production of esters and glycerol, including: (A) the continuous supply of fats and oils and alcohol to the heater, heating the components, (B) the reaction of heated fats and oils with heated alcohol in the absence of a catalyst in the reactor, (C) cooling the product reactions and pressure reduction, (D) removing alcohol from the mixture, and (E) separating the esters from glycerol, the heating temperature of the alcohol and the temperature of the mixture in the reactor below the temperature of the critical alcohol temperature, the pressure in the heater and pressure the reactor pressure is lower than 0.7 MPa (see JP200103, 1991).

The disadvantage of this method is that the process is unreasonably delayed in time and also requires large reaction volumes.

The closest analogue is a method for treating an oil composition containing saturated and unsaturated fatty acids in the form of triglycerides by transesterifying it with alcohol (C ₁ -C ₆ ) in the presence of lipase, followed by product separation, characterized in that practically anhydrous alcohol is used in an amount of not more than 15 molar equivalents based on the amount of triglycerides and lipase, which preferably catalyzes the transesterification of saturated and monounsaturated fatty acids and separates the remaining f stock enriched in glycerides of polyunsaturated fatty acids from a fraction containing the esters of saturated and monounsaturated fatty acids derived from transesterification (see. RU 2151788 C1, 27.06.2000).

The disadvantage of the closest analogue is the low yield of the product, the high cost of the process, as well as volumetric complex equipment.

The objective of the invention is to simplify the process and reduce the time of the process, increasing the yield of the product.

The problem is solved in that in the method for processing vegetable oil by transesterifying it with alcohol, separating the obtained products into fractions, according to the invention, rapeseed oil is used as vegetable oil, and ethanol obtained by sparging carbon dioxide of biomass of immobilized granulated yeast with carbon dioxide is used. the ratio of 1:12 to a homogeneous state, the resulting mixture is sent to the transesterification reactor, in which the transesterification is carried out at a rate a temperature of 350-400 ° C and a pressure of 35-50 MPa for 20 minutes, cool the mixture and fed to the extractor, in which the reaction mixture is subjected to temperature control at a temperature of 250 ° C, then carbon dioxide is extracted under supercritical conditions at a flow rate of carbon dioxide of 40 l / h at a temperature of 350 ° C and a pressure of 35 MPa, the resulting homogeneous mixture is fed into the first separator to separate glycerol from the target product at a pressure of 0.5 MPa and a temperature of 20-30 ° C, the target product is fed into a second separator to separate the fatty ethyl etheracid from carbon dioxide at a pressure of 0.2 MPa and a temperature of 15 ° C.

According to the invention, the carbon dioxide released in the second separator is recycled.

The technical result is a significant reduction in the reaction time, increased conversion (> 95%), the absence of saponification products, increased environmental friendliness of the process due to the use of carbon dioxide, which makes it possible to extract almost complete carbon from supercritical conditions from plant materials, exhibits universal dissolving properties of the spectrum biologically active compounds. In addition, carbon dioxide is relatively environmentally friendly, and it is removed from the extract by simple evaporation in the last stages of the technological cycle. This means that the final extract does not contain traces of solvent, and all this together provides a very high environmental friendliness of the production process. Biofuel production in supercritical ethyl alcohol environment greatly simplifies the process, and therefore, the cost of biofuel production is no less significantly reduced. The use of supercritical ethyl alcohol significantly increases the ecological "purity" of the entire production, since the whole process takes place in closed loops.

Selective extraction of the resulting mixture in a non-polar volatile solvent should be carried out at a pressure of at least 35 MPa, since in this case the dissolving ability of carbon dioxide is significantly reduced, and the process speed and degree of extraction are accordingly reduced. Increasing the pressure of carbon dioxide in the extraction process of more than 35 MPa, ceteris paribus, complicates the hardware and technological parts of the method, which reduces its technical and economic parameters and the cost of the target product.

For yeast synthesizing ethyl alcohol, the most acceptable method of immobilization in alginate gel. Alginate is a polysaccharide derived from brown algae.

It is affordable, relatively cheap and has no toxic effect on yeast. Nutrients easily diffuse into alginate gel. The essence of the immobilization technique is that the suspension of yeast cells is mixed with a solution of sodium salt of alginate, and droplets are formed using a dosing device that fall into a solution of calcium chloride. In the presence of calcium ions, the alginate solution "cross-links" into a gel, forming granules of immobilized granular yeast (IHD) of a spherical shape.

The forming device for alginate granules is designed to obtain IHD with the following characteristics:

- the content of calcium alginate is not more than 5%;

- the content of yeast biomass is not less than 15%;

- the diameter of the granules from 3 ± 0.5 to 6 ± 0.5 mm in increments of 1 mm;

- mechanical strength of the granules - not less than 0.05 MPa;

- bulk density is in the range of 0.6-0.7 g / cm ³ ;

- abrasion - not more than 5-7%;

- stability during operation in flowing mode - at least 720 hours.

The method is as follows.

Pellets are produced in a glass vessel with a working volume of 100 l, equipped with a single-tiered four-blade mixer, driven by an 0.55 kW AC motor with frequency regulation. The speed interfered with should be regulated from 50 to 400 rpm.

An alginate granule forming unit with the above characteristics should be placed in the upper part of the vessel. For this, the supply system of the main and cross-linking solution should provide a variable flow rate from 1.0 to 10.0 l / min independently for each channel. At the lower point of the vessel, a drain with shut-off valves consisting of membrane valves should be provided, which allows the washing and waste solution to be drained into the sewer or the product can be transferred to the granule washing unit from calcium chloride. The choice of the direction of discharge - manually. Sterilized yeast and alginate are sterilized using a torch and introduced through the ports in the top cap into the first vessel. The mixer is turned on, after 30 minutes the stock solution is ready for use in the process. Calcium chloride and process water are sterilely fed into the second vessel; the components are mixed. NaCl and process water are sterilely fed into the third vessel, the components are mixed. Nutrient medium and process water are sterilely fed into the fourth vessel, the components are mixed. The crosslinking solution obtained in the second vessel is mixed with the basic solution obtained in the first vessel. Drops falling into the crosslinking solution turn into granules and settle in the bottom. The obtained granules are washed with a stream of saline from calcium chloride. As a result of the developed technology for processing immobilized granular yeast, high-purity ethyl alcohol is obtained by sparging it with carbon dioxide.

Pressure tanks with a volume of 1 liter (equipped with a measuring window, designed for a pressure of 10 atmospheres and a temperature of 100 ° C) are filled with oil and ethanol each. Tanks are under pressure of nitrogen supplied from the cylinder.

When the exhaust valve is opened, raw materials under pressure enter the mixing chamber equipped with a mixer.

Before entering the mixer, the components are cleaned through filters. The volumetric ratio of oil: ethanol is 1:12. The mixture is mixed until homogeneous and then sent to the transesterification reactor.

The reactor is a thermostatically controlled cylindrical tank with a volume of 2 liters (200 mm × 56 mm). The maximum permissible pressure of the reactor is 70 MPa, the critical temperature is 500 ° C. To create and maintain a supercritical state, namely T = 300 ° C, P = 35 MPa, thermostatic control and a piston supercharger were used. The supercharger is a cylinder divided by a piston. The principle of its action is as follows. One part is filled with an inert gas, and water (incompressible liquid) is supplied to the other with a high-pressure water pump. When you open the valve between the gas compartment of the piston and the reactor, the pressure in the system increases. Thus, by adjusting the water supply, the pressure in the reactor is adjusted to the required value (about 35 MPa).

The mixture is transferred under pressure to a heated reactor (with an internal temperature of about 300 ° C), then, using a supercharger, the system creates the necessary conditions for the reaction to proceed. Empirically, it was found that the optimal reaction time is 20 minutes. The reaction yield after a twenty-minute exposure is 95.7%. After 20 minutes, the reaction mixture, passing through the refrigerator, enters the extractor.

The transfer is carried out by opening the connecting valves. In the extractor, the reaction mixture is thermostated to a temperature of 250 ° C. Then carbon dioxide is fed into the extractor. The feed is carried out using a piston supercharger. The required pressure is 22-24 MPa. These conditions (250 ° C and 24 MPa) are necessary for the formation of a supercritical state of the mixture (based on carbon dioxide). In the supercritical state, the components of the mixture are in the homophase.

The resulting homogeneous mixture is transferred (due to the pressure drop) to a separator in which glycerol is separated from the target product (P _slave = 0.5 MPa, T = 20-30 ° С). The separation of the product occurs due to the stepwise depressurization in the separator. The obtained glycerin contains impurities of unreacted ethanol, soap, water. For its commercial implementation, additional purification is required.

The fatty acid ethyl ester in the gas phase is carried away by the flow of carbon dioxide into the next separator (P _slave = 0.2 MPa, T = 15 ° C). The separator is the separation of the target product, its condensation on the walls of the vessel. The separator is equipped with a compressor - receiver system that directs carbon dioxide for recycling. Gas can be pumped into a cylinder or into a piston supercharger.

The invention is illustrated by the following examples, which, however, do not cover, and even more so do not limit the entire scope of the claims of this invention.

Example 1

The biomass of immobilized granular yeast obtained in the above manner is treated with carbon dioxide by sparging to obtain ethyl alcohol. Rapeseed oil is mixed with ethyl alcohol at a ratio of 1:12 to a homogeneous state. The resulting mixture is sent to the transesterification reactor, in which the transesterification is carried out at a temperature of 350 ° C and a pressure of 50 MPa for 20 minutes. Next, the mixture is cooled and fed to the extractor, in which the reaction mixture is subjected to temperature control to a temperature of 250 ° C. The resulting mixture was extracted with carbon dioxide under supercritical conditions at a flow rate of carbon dioxide of 40 l / h, at a temperature of 350 ° C and a pressure of 35 MPa. The resulting mixture is fed to separators for separation. In the first separator for separating glycerol from the target product, the process is carried out at a pressure of 0.5 MPa and a temperature of 20 ° C. In the second separator for the separation of ethyl ester of fatty acid from carbon dioxide, the process is carried out at a pressure of 0.2 MPa and a temperature of 15 ° C.

Example 2

The biomass of immobilized granular yeast obtained in the above manner is treated with carbon dioxide by sparging to obtain ethyl alcohol. Rapeseed oil is mixed with ethyl alcohol at a ratio of 1:12 to a homogeneous state. The resulting mixture is sent to the transesterification reactor, in which the transesterification is carried out at a temperature of 400 ° C and a pressure of 35 MPa for 20 minutes. Next, the mixture is cooled and fed to the extractor, in which the reaction mixture is subjected to temperature control to a temperature of 250 ° C. The resulting mixture was extracted with carbon dioxide under supercritical conditions at a flow rate of carbon dioxide of 40 l / h, at a temperature of 350 ° C and a pressure of 35 MPa. The resulting mixture is fed to separators for separation. In the first separator for separating glycerol from the target product, the process is carried out at a pressure of 0.5 MPa and a temperature of 30 ° C. In the second separator for the separation of ethyl ester of fatty acid from carbon dioxide, the process is carried out at a pressure of 0.2 MPa and a temperature of 15 ° C.

Thus, the claimed invention allows to simplify the process, reduce the time of the process and increase the yield of the product.

Claims (2)

1. The method of processing vegetable oil by transesterification with alcohol, the separation of the obtained products into fractions, characterized in that rapeseed oil is used as vegetable oil, and ethanol obtained by sparging carbon dioxide of biomass of immobilized granular yeast at a ratio of 1 is used as alcohol : 12 to a homogeneous state, the resulting mixture is sent to the transesterification reactor, in which the transesterification is carried out at a temperature of 350-400 ° C and a pressure of 35-50 MPa, 20 min, cool the mixture and feed it into the extractor, in which the reaction mixture is subjected to temperature control at a temperature of 250 ° C, then carbon dioxide is extracted under supercritical conditions at a flow rate of carbon dioxide of 40 l / h, at a temperature of 350 ° C and a pressure of 35 MPa, the resulting homogeneous mixture is fed into the first separator to separate glycerol from the target product at a pressure of 0.5 MPa and a temperature of 20-30 ° C, the target product is fed into the second separator to separate the fatty acid ethyl ester from carbon dioxide at a pressure of 0 , 2 MPa and a temperature of 15 ° C. 2. The method according to claim 1, characterized in that the carbon dioxide released in the second separator is recycled.