RU2379332C1 - Improved method of producing methyl ether of fatty acid (biodiesel) via reesterification of oil triglycerides - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing methyl ether of fatty acid (biodiesel) from oil, containing triglycerides and obtained from plants involves: (i) squeezing out oil from seeds and separation of the residue for use as manure, (ii) neutralisation with an alkali of the excess free fatty acid contained in the oil, and separation of the soap residue, (iii) addition of an antioxidant and blowing the oil with dry air to reduce water content, (iv) treatment of the oil with the respective amount of methanol solution of KOH, dried over anhydrous sodium sulphate, (v) separation of the glycerin layer formed during the reaction, (vi) treating the methyl ether of fatty acid with glycerin in two steps to further reduce content of methanol, catalyst and other impurities in the layer of methyl ether of fatty acid, (vii) separation of glycerin, (viii) washing the layer of methyl ether of fatty acid with water in two steps to minimise content of impurities, (ix) separation of washing water, (x) addition of an additional amount of antioxidant to the methyl ether of fatty acid and with blowing dry air to minimise water content, (xi) combination of the glycerin layers and treatment with SO_x or flue gas to convert spent KOH catalyst to K₂SO₄ or K₂CO₃ respectively, (xii) setting the pH to approximately 7 and distillation of methanol from the glycerin layer, (xiii) hot centrifuging the remaining mass to separate potassium salts from glycerin, (xiv) washing the salt to remove impurities, (xv) separation of the required amount of crude glycerin for washing the layer of methyl ether of fatty acid in the next portion as well as for other uses where crude glycerin is used, and (xvi) distillation of the remaining crude glycerin with low content of water to obtain pure glycerin.

EFFECT: obtaining biodiesel which meets international standards with high output.

21 cl, 18 ex

Description

The present invention relates to an improved method for producing biodiesel (biodiesel) by transesterification of triglycerides of oils derived from plants. More specifically, the invention relates to the production of fatty acid methyl ester from oil made from whole seeds of Jatropha curcas , a plant that can be cultivated on vacant lands in India and other countries.

The need for fossil fuels and its negative environmental impact has sparked interest in renewable energy sources, such as solar, wind, tidal, draft animal power and the energy that can be obtained from plant sources.

You can refer to the review article entitled “Biodiesel Production by Transesterification of Oils” ( Journal of Bioscience and Bioengineering, vol. 92, No. 5, (2001), 405-416 ), which discusses the disadvantages of using vegetable oils directly instead of fossil fuels and explores three approaches to overcome these shortcomings, namely pyrolysis, microemulsification and transesterification. The article shows that transesterification is the preferred method and can be carried out in three ways, namely using acid catalysis, basic catalysis and enzymatic catalysis. Although each pathway has its merits, basic catalysis is currently the most suitable for industry due to the significantly higher reaction rate and low cost of the catalyst. Known disadvantages of the continuous alkaline catalysis process are the high temperature (60-70 ° C), the problems caused by the presence of free fatty acids in the feed, the difficulties associated with the release of glycerol and methanol, and the need to repeatedly wash the methyl ester with water to effectively clean it. Catalyst deactivation and decomposition of the effluent are not discussed.

Reference may be made to the same review article, which states that in a report entitled “Review of the Operation of Biodiesel and Petroleum Diesel”, Sheehan et al. (Report of the National Renewable Energy Laboratory (NREL) and US Department of Energy (DOE), Assignment No. BF886002, May (1998)), it was shown that the benefits of using biodiesel are proportional to its concentration in a mixture with petroleum diesel fuel. The total CO ₂ emission when using 100% biodiesel is 78.45% lower than in the case of petroleum diesel fuel, and in a mixture containing 20% biodiesel, the total CO ₂ emission is reduced by 15.66%.

You can also name the article entitled “Biodiesel: Renewable Energy Fuels,” NSK Prasad (Chemical Weekly, August 17, 2004, p.183-188), which says on page 188: “ Biodiesel is widely used in Europe. In Germany, there are more than 1,500 gas stations selling biodiesel at gas stations. France is the world's largest producer. All French diesel fuel contains 2-5% biodiesel, which will soon be sold throughout Europe. In the 1990s, France launched local production of biodiesel (known as diester there) by transesterifying rapeseed oil. It is mixed in a ratio of 5% with conventional diesel fuel and in a ratio of 30% with diesel fuel used by a fleet of vehicles (public transport). Renault, Peugeot and other manufacturers have certified truck engines for partial use of biodiesel. Experiments are being conducted with diesel fuel containing 50% biodiesel. ”

You can refer to the Google search engine: http://www.google.co.in/search?hl=en&q=Biodiesel+preparation&btnG=Google+Search&meta, which gives 13,200 links to get biodiesel.

You can point to the article entitled “ Integrated Biodiesel Production: A Comparison of Different Systems of Homogeneous Catalysts ”, Vicente et al. ( Bioresource Technology 92 (2004) 297-305 ), which describes a method for transesterification of vegetable oils in the presence of various basic catalysts. The authors report that the maximum yield of biodiesel obtained by alkaline methanolysis in laboratory experiments with oil containing <0.5% free fatty acids (FFA) was approximately 85.32% and 90.54% in the presence of NaOH and KOH catalysts, respectively . Besides the fact that the yield was less than expected, other disadvantages of the method are the need for transesterification under conditions different from the usual ones, and the lack of a solution to the problem of catalyst removal and treatment of the effluent.

You can refer to Bamhorst et al., US patent No. 6489496, which described a method for transesterification of triglycerides with the continuous removal of the glycerol formed in the reaction in a centrifuge to increase the reaction rate. The main disadvantage of this method is that the transesterification is carried out at 70 ° C. The method does not consider the separation of the catalyst from glycerol, the removal of methanol from the resulting ester and the reuse of ethanol, therefore, the process is not economical for industrial implementation.

US Pat. No. 6,712,867 to Boocock et al., For a method for producing fatty acid methyl esters from triglycerides, which describes a method for transesterification of triglycerides in methanol and / or ethanol in the presence of an alkaline catalyst and an additional solvent such as ether, can be cited. The main disadvantages of the method are the use of an additional solvent, an elevated temperature compared to the usual one and the absence of attempts to solve the problem of separation of spent catalyst.

You can refer to the website http://www.svlele.com/biodiesel_in_india, where a detailed design of a plant for the production of biodiesel with a capacity of 10 thousand liters per day is given. The proposed project is based on the prior art, which, as shown above, has important limitations.

Reference is made to U.S. Patent Application No. 20030229238, December 11, 2003, Fleisher, Christian A., for a continuous transesterification process that includes a perfect displacement flow reactor with a one-pass contact time of up to about 10 s and a conversion of at least 70%. The main disadvantage of this method is the transesterification at high temperature and pressure.

In an article by W. Zhou et al entitled “Preparation of Ethyl Esters by Single Phase Basic Catalyzed Ethanolysis of Vegetable Oils” ( JAOCS vol. 80, 367-371, 2003), where the main catalyzed transesterification of vegetable oils was carried out in the presence of additional solvents, tetrahydrofuran (THF ) and ethanol - at elevated temperature. The disadvantage of this work is that the transesterification is carried out at elevated temperatures and an additional solvent is used in the system, which complicates and increases the cost of the process. In addition, the work does not consider the allocation of the catalyst in any form and excess ethanol used in the reaction.

Several literature reviews on the use of lipases as catalysts for industrial production of biodiesel are known; for example, Bradin (US Pat. No. 6,398,707) used a pre-treated immobilized lipase for transesterification or esterification. In addition, a pre-treated immobilized lipase is prepared by soaking the immobilized lipase in an alcohol containing at least three carbon atoms, and up to 48 hours are required for pre-treatment of the lipase. Such methods are too slow for industrial use. In another article published by Watanabe et al. [ "Continuous production of biodiesel from vegetable oil using immobilized Candida antarctica Lipase", JAOCS, vol. 77, pp.355-360, 2000], there are three main difficulties in using lipase to produce biodiesel. The first difficulty is that lipase much more expensive than alkali. Secondly, the lipase method requires up to 48 hours to complete the reaction, which is much longer than with the main catalysis. The third difficulty is that the lipase activity is relatively low and requires preliminary treatment with alcohol containing not less than e three carbon atoms. Another problem enzymatic catalysis, which are not discussed in this article consists in that the transesterification with methanol, which is a preferred alcohol for obtaining biodiesel proceeds extremely slowly and in most cases only a low conversion, if any, are.

Although other ways to solve the problems associated with alkali-catalyzed production of biodiesel have been described, by using alternative catalysts such as enzymes, acids and heterogeneous catalysts, it would be much better to improve the basic-catalyzed process itself by overcoming these drawbacks. One of these improvements is a two-stage transesterification, but the overall reaction yield is reduced, and it would be desirable to obtain high-quality biodiesel that meets the technical requirements of EN14214 in one stage. There are also no reports on any suitable methods for solving the problem of processing crude methyl esters of fatty acids obtained by transesterification of triglycerides with methanol, and the problem of product / reagent losses with the waste water stream. In addition, since biodiesel improves the environment, it would be highly desirable to obtain such biodiesel from raw materials under normal conditions. Another limitation of the prior art is that attempts to maximize the output of biodiesel sometimes lead to a complication of the method, and it would be useful to have a simpler method in which other useful products would be obtained along with biodiesel, and the overall production method would remain as simple as possible.

You can refer to the Google search engine: http://www.google.co .in / search? Hl = en & q = Biodiesel + Production + from + Jatropha + oil & btnG = Google + Search & meta , which contains 141 links to get biodiesel from Jatropha curcas oil . Oil obtained from the unconventional plant Jatropha curcas is non-edible.

You can link to a book called Biofuels and Industrial Products from Jatropha curcas , edited by GM Gublitz, M. Mittelbach, M. Trabi, Eds. (1997), in which GD Sharma et al. reported that the plant J. curcas can be grown in various arid or semi-arid climates; it is resistant to weather changes, easily propagated by seeds or cuttings and is not eaten by goats and cattle. We can also cite an article by B. Schmook and L. Serralta-Peraza in the same book, in which the authors argue that “ taking into account the climatic and soil conditions of Yucatan Peninsula, which are not very favorable for modern agriculture, J. curcas can be considered optimal option . " Obviously, this plant is suitable for cultivation in the wasteland, and in the future, large quantities of biodiesel will be available from empty land if biodiesel of the desired quality can be obtained in a simple and cost-effective way.

Reference may be made to the articles in the above book by E. Zamora et al. and MN Eisa for the transesterification of J. curcas oil. These articles do not reveal many of the details of this method.

You can also refer to the same book, which in different chapters discusses the use of oilcake Jatropha , soap and glycerin.

The website of the Petroleum Conservation Research Association (http://www.pcra.org/petroleuml6.html), which states that triglycerides, including Jatropha oil, “ can easily be transesterified in the presence of an alkaline catalyst (liquor) at atmospheric pressure and a temperature of about 60-70 ° C in excess methanol. At the end of the reaction, the mixture was allowed to settle. Excess methanol is removed by distillation, sent to a distillation column for purification and reused. The lower layer of glycerol is removed, and the upper layer of methyl ether is washed with water to remove the captured glycerol. Fatty acid methyl esters are called biodiesel. ” Besides the fact that the transesterification is carried out at elevated temperature, the layer from which methanol is isolated, or what is done with alkali, is not mentioned. The difficulties that are expected to arise when adding water to a layer of crude biodiesel during water washing are also not considered .

Mention should be made of the Minutes of Meeting of Adhoc Panel of experts of PCD 3 protocol established by the Indian Bureau of Standards for the final approval of biodiesel specifications of June 17, 2004, which states: “Two important intercontinental standards for biodiesel are known, namely EN 14214 and ASTM D 6751. The scope of EN 14214 includes requirements for biodiesel when it is 100% used and also when mixed with diesel fuel, while ASTMD 6751 includes requirements only for mixtures containing biodiesel . " The article also says: “ Given the fact that India intends to produce biodiesel from non-edible vegetable oils, the authors express concern that it will be extremely difficult to achieve compliance with EN technical specifications .”

Reference may be made to an article by MN Eisa entitled “ Production of Ethyl Esters as Substitutes for Diesel Fuel in Developing Countries ” (pp. 110-112), in Abstracts of the Biofuels and Industrial Products Conference from Jatropha curcas , 23-27 Feb. 1997, held in Managua, Nicaragua. The article discloses the preparation of ethyl ester from oil by basic catalyzed transesterification. The disadvantages of this method are the use of a large excess of ethyl alcohol (up to 70 parts per 100 parts of oil), the absence of a catalyst separation stage and the reaction temperature of about 70 ° C.

You can also cite the publication N. Foidl et al, entitled “ Jatropha Curcas L as a Raw Material for Biofuel in Nicaragua ” ( Bioresource Technology , 58, 1996, pp. 77-82), which states that for the development of countries like Nicaragua, Jatropha curcas is a very energetically promising plant, because it can be grown on very poor soils and it gives a high average seed yield. This publication also describes an effective process for the preparation of methyl ester from oil by means of a two step basic catalyzed transesterification. An oil containing 0.60-1.27% FFA is obtained by squeezing the kernels of Jatropha curcas seeds and then treating with 1.5 equivalents. MeOH and 1.3% KOH in a continuous reactor with the reuse of 90-93% methyl ester with fresh oil. The remaining phase of the ether is mixed with 5% warm water and then centrifuged to remove excess methanol, remaining soap and glycerin. The main disadvantages of the method are: (i) the need to peel the seeds, (ii) low productivity due to the high ratio of recycle and (iii) high concentrations of phosphorus (17.5 ppm) and water (0.16%), which make product unsuitable for use as pure biodiesel. The difficulties of processing crude methyl ether, the effluent, and the problem of deactivating the catalyst used are not mentioned.

You can refer to the composition of the oil from the seeds of J. Curcas of the Caboverde species and Nicaragua species, given in the above article. This oil is indicated to contain 290 ppm. phosphorus, the concentration of which in biodiesel can be reduced to 17.5 ppm by this method, but to obtain biodiesel with a phosphorus content of <10 ppm Resin must be removed according to the specifications of EN 14214 for B100 biodiesel.

An analysis of the prior art shows that reports that pure biodiesel fuel was obtained from Jatropha curcas oil according to the technical specifications of EN 14214 are absent and there is no information on the receipt of such premium biodiesel from oil squeezed directly from whole seeds. Moreover, there are no reports of biodiesel production under normal processing conditions that would minimize the generation of greenhouse gases. In the prior art, there is some information about the economics of production and attempts to evaluate additional waste streams and flue gases. The lack of an acceptable solution to the problem of spent alkaline catalyst in combination with the cost of the catalyst may lead to the need to use less than optimal amounts of catalyst, which could adversely affect the ongoing method. There is also no data on the optimization of the method, taking into account the cost of all products.

Reference is made to an article by H. Scherzberg et al., Entitled “A New Method for the Production of Potassium Sulphate by Messo Pilots” (Phosphorous & Potassium, 178, March-April 1992, p.20), which described the use of potassium sulfate as an excellent fertilizer containing both potassium and sulfur, and a plant nutrient, also with a low chloride index.

Reference may be made to an article devoted potassium compounds, H. Schultz et al., In Ullmann's Encyclopedia, 6 ^th Edition, 2002, which indicates that the production of potash potassium carbonate and carbon dioxide is the most common method. And then it says: “The glass industry is the most important consumer of K ₂ CO ₃ . Large quantities are also needed for the production of potassium silicate . " In addition to many other uses, potassium carbonate is used as a fertilizer for acidic soils.

Reference is made to US Patent No. 6174501, H. Noureddini, for a system and method for producing biodiesel with a reduced viscosity and a cloud point below thirty-two (32) degrees Fahrenheit, which describes the use of crude glycerol to produce glycerol esters. It is shown that these esters lower the cloud point of biodiesel obtained by transesterification of triglycerides by base catalysis.

Subject of invention

The main subject of the present invention is to propose an improved method for producing methyl ester of a fatty acid (biodiesel) by transesterification of an oil containing triglycerides.

Another object of the present invention is to propose a method for producing biodiesel from oil containing triglycerides of plant origin.

Another subject of the present invention is to propose an improved method for producing biodiesel from Jatropha oil that meets the specifications of EN14214 and is suitable for use as pure biodiesel in mobile and stationary engines without modifying the engine.

Another subject of the present invention is the preparation of biodiesel under ordinary conditions from crude oil squeezed from whole seeds of Jatropha curcas .

Another subject of the present invention is the production of biodiesel with the lowest energy consumption and minimal waste generation.

Another object of the present invention is to reduce the content of free fatty acids in oil to <0.5% by treating crude oil under normal conditions with the right amount of caustic soda solution of optimal concentration and at the same time removing pigments, phospholipids and other impurities in the crude oil along with a soapy residue.

Another subject of the present invention is the conversion of a soap residue containing 15-20% residual oil to a bar of soap.

Another object of the present invention is to purge the neutralized oil with dry air to reduce the water content of the oil.

Another object of the present invention is the drainage of a methanol solution of KOH, used for transesterification of oil, using anhydrous sodium sulfate.

Another object of the present invention is an improvement in the method of processing crude fatty acid methyl ester after transesterification of the oil.

Another object of the present invention is to wash the crude methyl ether with additional portions of glycerol after separating the glycerol layer to extract most of the methanol, catalyst and other impurities in the methyl ether into the glycerol layer in order to solve the problems associated with emulsification and foaming, as well as undesired impurity reactions .

Another subject of the present invention is the use of water with a total solids content of <50 ppm. for washing fatty acid methyl ester.

Another subject is the addition of an antioxidant to water-washed biodiesel and purging with dry air to reduce the water content to <500 ppm.

Another object of the present invention is to take advantage of an improved processing method and method for producing biodiesel with a yield of 96% (based on neutralized oil) and a total glycerol content of <0.15% by single-stage transesterification of the neutralized oil.

Another object of the present invention is the minimization of indicators of COD (chemical oxygen demand) and TDS (total salt content) in the wash water.

Another object of the present invention is to combine all of the KOH used and the excess methanol in the glycerol layer formed during the reaction and used to wash the crude fatty acid methyl ester.

Another subject of the present invention is the treatment of an alkaline glycerol layer with SO _x or concentrated sulfuric acid to convert spent catalyst to potassium sulfate, which is used as a solid fertilizer that can be filtered and washed.

Another object of the present invention is the treatment of an alkaline glycerol layer with fuel gases from a boiler of a biodiesel plant for converting spent catalyst into potassium carbonate, which can be filtered and washed.

Another object of the present invention is the distillation of methanol from the glycerol layer for reuse after drying.

Another object of the present invention is the reuse of a portion of the crude glycerol remaining after distillation of methanol for washing the crude methyl ester as described above.

Another subject of the present invention is the use of a portion of crude glycerol to produce glycerol ester and lower the cloud point of biodiesel, as described in the prior art.

Another object of the present invention is the distillation of the remaining crude glycerol with a low water content to obtain cheap purified glycerol.

Another subject of the present invention is to propose a biodiesel production model in which biodiesel is produced in agricultural areas near plant cultivation centers, both biodiesel and process by-products can be maximally used on site.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide an improved method for producing fatty acid methyl ester (biodiesel) from an oil mechanically squeezed from whole seeds of Jatropha curcas . Biodiesel is obtained from crude oil under ordinary conditions by, first, removing FFA and other impurities from the oil and then by a one-stage KOH catalyzed transesterification followed by a new treatment based on the initial washing of the crude fatty acid methyl ester with glycerol and then with water to remove traces of the remaining impurities. The new treatment involves combining the entire excess of methanol and alkali in glycerol, which can then be processed with lower cost and energy costs to separate individual components from the mixture (methanol, glycerol, potash). Another innovation is the use of fuel gases in the specified method. Biodiesel that meets the technical specifications of EN14214 is obtained with a yield of> 96% (w / w) based on neutralized oil, and all by-products obtained are commercial products. As a result of the proposed measures, a minimum effluent is obtained.

Inventive step

(1) The main inventive concept is that the improvement of the method for producing methyl ester of Jatropha oil after transesterification is a key point for improving the economy of the whole method and the quality of biodiesel.

(2) Another inventive concept is that although methanol is slightly soluble in Jatropha oil, it is much better soluble in methyl ether obtained from Jatropha oil, i.e. in biodiesel; as a result, significant amounts of methanol and an alkaline catalyst used in the transesterification reaction, as well as soap, remain solubilized in biodiesel at the end of the reaction.

(3) Another inventive concept is that although it is desirable to solubilize methanol and the catalyst in biodiesel to complete the transesterification reaction, their subsequent removal from the biodiesel by washing with water creates the following difficulties: (i) methyl ether is partially hydrolyzed in the presence of water and alkali to form soap, which promotes the formation of an aqueous emulsion of biodiesel, so long-term aging is required to break the emulsion, and (ii) as a result, this circumstance negatively affects the yield and quality of of biodiesel, (iii) the loss of biodiesel with the outgoing water, if not reached a clear separation of layers, (iv) an increased consumption of methanol as methanol dissolved in biodiesel will be lost with water, (v) part of the alkaline catalyst will be discharged into the waste water and (vi) the treatment of alkaline water waste will be costly and problematic.

(4) Another inventive concept is that with a two-stage transesterification, the concentration of methanol, catalyst and soap in methyl ether will be higher, because the relative fraction of glycerol formed in the second transesterification step is reduced and, therefore, the release of methanol, catalyst and soap will be less effective. On the contrary, the mass of the separated glycerol layer is approximately the same as the mass of KOH in methanol when implementing a one-stage transesterification with the optimal amount of methanol and KOH, as a result of which the fatty acid methyl ester layer contains a small amount of residual impurities that need to be removed.

(5) Another inventive concept is to use additional glycerol obtained by isolating glycerol in the preceding stages of biodiesel production to isolate residual methanol, catalyst, and other impurities remaining in the biodiesel at the end of the transesterification reaction, such glycerol layer being carefully separated from the ether layer after short settling.

(6) Another inventive concept is to wash the residual methanol, catalyst and free glycerol in methyl ether with water; in this case, the ester is not hydrolyzed and the emulsion is not formed, but a completely detachable layer of methyl ether (biodiesel) is formed, which contains a significantly lower amount of impurities of free fatty acids, methanol, an alkali metal, total glycerol and free glycerol in comparison with the values determined by technical EN14214 conditions.

(7) Another inventive concept is to purge water-washed biodiesel with dry nitrogen or air at ordinary temperature to remove water to a residual concentration of <500 ppm.

(8) Another inventive concept is to add an antioxidant to biodiesel after washing with water to minimize oxidative decomposition when purged with air and subsequent storage of the product.

(9) Another inventive concept is to obtain a pure golden yellow biodiesel from dark brown muddy crude Jatropha oil under ordinary conditions due to the advantages of the FFA neutralization step, in which most of the other impurities in the oil, such as pigments, phospholipids and insoluble substances, are removed along with soap.

(10) Another inventive concept is the semi-quantitative separation of spent KOH catalyst in the glycerol layer in the form of fertilizer - solid potassium sulfate or potassium carbonate.

(11) Another inventive concept is the cost-effective separation of methanol and glycerol from the glycerol layer while maintaining a minimum concentration of water corresponding to the KOH neutralization stoichiometry.

(12) Another inventive concept is to process the saponified mass obtained after removing free fatty acid from Jatropha oil with an additional amount of liquor to turn all the trapped oil into soap, and then, if desired, improve the quality of the soap by introducing glycerol, a by-product of the biodiesel production method .

(13) Another inventive concept is to process oil to produce biodiesel under ordinary conditions and save energy by performing heating operations only in a small volume of the glycerol layer.

(14) Another inventive concept is to minimize the waste water by purifying the methyl ester with glycerol before washing with water, and also reusing subsequent portions of the second series of washes in the first washing with water and using part of the water of the first washing to prepare the NaOH solution necessary for the oil neutralization steps and soap formation.

Description of the invention

Accordingly, the present invention is to provide an improved method for producing fatty acid methyl ester (biodiesel) from an oil containing triglycerides, which comprises: (i) squeezing the oil from whole seeds and separating oilcake for use as an organic fertilizer, (ii) neutralizing the excess free fatty acids in the oil with alkali and soap separation; (iii) adding an antioxidant and purging the oil with dry air to reduce the water content; (iv) treating the oil with an appropriate amount of methanol o KOH solution, dried over anhydrous sodium sulfate, v) separation of the glycerol layer formed during the reaction by a known method, (vi) two-step treatment of the fatty acid methyl ester layer with glycerol in order to further reduce the content of methanol, catalyst and other impurities in the methyl layer fatty acid ester, (vii) separation of the glycerol layers by a known method, (viii) washing the layer of fatty acid methyl ester with water in two steps to minimize the content of impurities to the desired values, (ix) separation of aqueous using conventional methods, (x) adding an additional amount of antioxidant to the fatty acid methyl ester and blowing with dry air to minimize the water content, (xi) combining the glycerol layers and treating with SO _x or flue gas to convert spent KOH catalyst to K ₂ SO ₄ or K ₂ CO _3, respectively, (xii) setting the pH to the desired level and distilling off the methanol in the glycerol layer, (xiii) hot centrifuging the remaining mass to separate the potassium salt from glycerol, (xiv) washing the salt to remove adhering Rome, (xv) separating the required amount of crude glycerol to flush the fatty acid methyl ester layer from subsequent operations and also for other applications where crude glycerin is directly used, and (xvi) distilling the remaining crude glycerol with a low water content to obtain purified glycerol.

In one embodiment of the present invention, the oil containing triglycerides can be obtained from plants, more specifically from Jatropha curcas .

In another embodiment of the present invention, the yield of fatty acid methyl ester (biodiesel) is about 94-98% based on the neutralized oil.

In another embodiment of the present invention, the average yield of oil mechanically squeezed from whole Jatropha curcas seeds used in the present invention was 20-30% (w / w).

In another embodiment of the present invention, an oil cake containing 5-10% oil is ground for use as an organic fertilizer.

In another embodiment of the present invention, the content of free fatty acid in freshly squeezed oil is 1.5-10.0% (w / w).

In another embodiment of the present invention, the oil is treated under normal conditions with a 5N caustic soda solution, the amount of alkali used being 0.7-1.0 eq. (based on FFA) depending on the initial content of FFA in the oil, as a result of which the content of FFA in the neutralized oil is 0.25-0.35% (w / w).

In another embodiment of the present invention, the neutralization method makes it possible to remove other impurities contained in the crude oil, such as phospholipids and dyes, together with soap and to obtain an oil of improved color, transparency and fluidity, which results in a golden yellow biodiesel and high transparency .

In another embodiment of the present invention, a soap containing 10-30% residual oil is treated with additional alkali and other ingredients to obtain a lumpy soap of the desired quality.

In yet another embodiment of the present invention, the water content of the neutralized oil is reduced from about 0.1% to about 0.01% by blowing with dry air after adding a suitable antioxidant at a concentration of 5-50 ppm.

In another embodiment of the present invention, KOH in methanol used for transesterification is treated with a stoichiometric amount (based on KOH) of anhydrous sodium sulfate to absorb water, which may be formed as a result of the reaction of alkali with alcohol.

In yet another embodiment of the present invention, said water removal steps increase the yield of methyl ester by 1-5% and at the same time reduce the yield of by-products that are difficult to dispose of.

In yet another embodiment of the present invention, the oil is transesterified with KOH in methanol in two stages, and preferably in one stage, using about 1.5-2 equiv. methanol and 1.5-2% (wt./wt.) KOH calculated on the neutralized oil.

In another embodiment of the present invention, the crude methyl ether layer, after removing the glycerol layer, is treated with additional glycerol (1-10%) to remove remaining impurities in the methyl ether layer and to prevent its entrainment with the water stream when washing with two portions of water containing <50 m .d. TDS, and more importantly, to prevent unwanted hydrolysis of the ester.

In yet another embodiment of the present invention, a portion of a first portion of wash water (typically 0.5-1.0 L per liter of biodiesel) containing 25000-35000 ppm. COD is used to produce liquor for the neutralization step, as well as to obtain bar soap from the soap residue, and the rest is treated before draining.

In yet another embodiment of the present invention, a second portion of the wash water containing 500-2000 ppm. COD, used for the first washing with water in the subsequent operation. In yet another embodiment of the present invention, the resulting methyl ester is treated with an antioxidant in an amount of 5-50 ppm, more specifically BHT (butylated hydroxytoluene), and purged with dry air to reduce the water content to <500 ppm.

In yet another embodiment of the present invention, the bulk of the KOH catalyst is collected in the glycerol layer, and it can be treated with a stoichiometric amount of concentrated sulfuric acid, or SO _x vapors, or flue gases to convert the spent catalyst into a useful potassium fertilizer, which is used directly in agriculture, with yield 95-100%.

In yet another embodiment of the present invention, methanol is isolated by distillation from the glycerol layer with a yield of 70-95%.

In yet another embodiment of the present invention, a portion of the crude glycerol after removal of the spent alkaline catalyst and methanol can be reused for further washing of the crude methyl ester.

In yet another embodiment of the present invention, the remaining glycerin with a minimum water content can be distilled and pure glycerin is obtained in a yield of 85-95%. The following examples are provided to illustrate, therefore, it should not be considered that they limit the scope of the present invention.

EXAMPLE 1

395 kg of whole Jatropha curcas seeds from Gujarat, India, were loaded into a mechanical screw press and received 100 kg of dark brown oil and 282 kg of oil cake. The free fatty acid (FFA) content of freshly squeezed oil was 4.42% (w / w). A portion of 4.27 kg of this oil was placed in a ten-liter glass vessel with a stirrer (200 rpm). With stirring, 155 ml of 5N NaOH solution (1.16 mol. Equiv.) Was added at room temperature over 15 minutes. Stirring was continued for 60 minutes, the saponified mass was filtered in vacuo and 0.68 kg of soap and 3.58 kg of clear light brown oil were obtained (yield 83.8%) with 0.30% (w / w) residual FFA

EXAMPLE 2

1187 kg of a single serving of Jatropha curcas seeds from the Indian state of Rajasthan was loaded into the mechanical screw press of Example 1 to give 270 kg of a dark yellow oil with 3.2% (w / w) FFA. A batch of 123.8 kg of oil was placed in a two hundred liter stainless steel vessel with a paddle stirrer (100 rpm) and 2.58 L of 5N NaOH solution (0.92 mol. Equiv.) Was added to the oil at room temperature over a period of 10 min. Stirring was continued for 40 min, the saponified mass was filtered on a high-speed centrifuge and 9.76 kg of solid soap and 115.8 kg of light yellow oil were obtained (yield 93.53%), containing 0.26% (w / w) residual FFA

EXAMPLE 3

194 kg of a separate portion of Jatropha seeds collected after the monsoon period were mechanically squeezed and 46 kg of cloudy black oil with 7.87% FFA (w / w) and 134 kg of oil cake were obtained. A portion of 1.75 kg of oil was placed in a three-liter glass vessel with a stirrer (200 rpm) and 95 ml of 5N NaOH solution (0.97 mol. Equiv.) Was added with stirring at room temperature over 10 minutes. Stirring was continued for 30 minutes, the saponified mass was filtered in vacuo to obtain 0.40 kg of soap and 1.43 kg of dark brown clear oil (81.7% yield) containing 0.267% (w / w) residual FFA.

Examples 1-3 show that samples of crude oil squeezed from whole Jatropha curcas seeds have different appearance and different FFA content; however, the proposed neutralization method can significantly improve the appearance of the oil and reduce the FFA content to the desired level. These examples also show that in order to minimize the loss of oil with soap and at the same time the required reduction in the FFA content in the neutralized oil, an optimal amount of alkali solution should be used.

EXAMPLE 4

2.67 kg of the neutralized oil from Example 1 were transesterified in a three-necked five-liter glass vessel with an anchor stirrer. A 0.530 kg solution of KOH in methanol was prepared in a separate vessel by adding 0.045 kg (1.68% (w / w) based on neutralized oil) KOH in 0.485 kg MeOH (1.64 mol equivalents based on neutralized oil ) with stirring for 15 minutes A portion of 0.372 kg of this solution was added to the oil with stirring at a speed of 200 rpm for 30 minutes at room temperature, and the contents were then stirred for 1 hour under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, then the glycerol layer was removed from the bottom of the vessel and weighed (0.36 kg). An aliquot of a 100 g oil / methyl ether layer was taken for analysis, and the remaining amount was then introduced into the transesterification reaction with the remaining amount (0.158 kg) of KOH in methanol. After stirring was stopped, 0.06 kg of the glycerol layer was separated and allowed to stand for 1 h. 2.54 kg of crude fatty acid methyl ester was obtained, which was then processed in the following manner.

They took 0.25 kg of crude methyl ether and repeated the experiments according to method C, except that 0.039 kg of glycerol was added in two portions, 0.032 kg and 0.007 kg, respectively. After adding the first portion and settling for 10 minutes, 0.035 kg of the glycerol layer was obtained, and in the second case, after settling for 1.5 hours, 0.012 kg was obtained, i.e. only 0.052 kg. Compressed air was passed through silica gel and the resulting dry air was used to purge the methyl ether layer for 45 minutes. Received 0.235 kg of a product containing 0.27% FFA, 0.05% total glycerol, <0.01% free glycerol, 0.048% water and <0.2 ppm each. sodium and potassium. The waste water (0.534 kg) contained 0.0089 g of KOH and 7100 ppm. COD.

EXAMPLE 5 (Comparative methods A, B, C)

2.67 kg of the neutralized oil from Example 1 were transesterified in a three-necked five-liter glass vessel with an anchor type stirrer. A 0.530 kg solution of KOH in methanol was prepared in a separate vessel by adding 0.045 kg (1.68% (w / w) based on neutralized oil) KOH in 0.485 kg MeOH (1.64 mol equivalents based on neutralized oil ) with stirring for 15 minutes A portion of 0.372 kg of this solution was added to the oil with stirring at a speed of 200 rpm at room temperature, and the contents were further stirred for 1 hour under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 hour, after which the glycerol layer was taken from the bottom of the vessel and weighed (0.36 kg). An aliquot of a 100 g oil / methyl ether layer was taken for analysis, and the remaining amount was further transesterified with the remaining amount (0.158 kg) of KOH in methanol. After stirring was stopped, 0.06 kg of the glycerol layer was separated and the contents allowed to stand for 1 h. 2.54 kg of crude fatty acid methyl ester was obtained, which was then treated by methods ( AC ) as described below.

Method A 0.25 kg of crude methyl ether was placed in a separatory funnel and shaken with 0.175 kg of water. A foamy emulsion was obtained, which was divided into two different but fuzzy layers after about 24 hours. The aqueous layer was removed and 0.175 kg of water was again added to the separatory funnel to repeat the operation. It took approximately 20 hours to separate into layers. This operation was repeated six more times with water containing <50 ppm. TDS, after which a clear methyl ester was obtained. Methyl ether was filtered through a layer of anhydrous sodium sulfate to give 0.205 kg of a final product containing 0.41% FFA, 0.05% total glycerol and 0.01% free glycerol. From wash water containing 0.395 g of KOH and 43500 ppm. COD, received 1.45 kg of waste water.

Method B 0.25 kg of crude methyl ether was placed in a distillation flask and heated to a temperature of 65-75 ° C to distill off the residual methanol in vacuo. The mass became jelly-like and could not be processed further.

Method C 0.25 kg of crude methyl ether was placed in a separatory funnel, 0.039 kg of glycerin was treated with stirring for a minute, and allowed to stand for 90 minutes. Glycerol and methyl ether were separated into two different transparent layers. It was found that the mass of the depleted glycerol layer increased to 0.048 kg. Then 0.175 kg of water was added to the methyl ether layer, the contents were shaken and allowed to stand for 2.5 hours. The aqueous layer was easily separated. The methyl ether layer was then washed twice more (0.175 kg x 2) with water (<50 ppm TDS). It was found that the methyl ether layer contains 0.2% water, it was filtered through a layer of anhydrous sodium sulfate and 0.235 kg of the final product was obtained containing 0.27% FFA, 0.05% total glycerol, <0.01% free glycerol, 0.1% water and 12 ppm impurities of sodium. The waste water (0.530 kg) contained 0.029 g of KOH and 21800 ppm. COD.

The treatment methods given in Examples 4-5 show that treating the crude methyl ester with glycerol prior to washing with water leads to a significant increase in yield, maintaining the amount of FFA in a neutralized oil and a significant reduction in the volume of effluents and COD. In addition, the examples show that the addition of glycerol in two portions is very useful, because reduces drains. The examples also show that purging the purified methyl ester with dry air is the best way to reduce the water content at ordinary temperature. (It was found that after drying the purified methyl ether on a rotary evaporator at 70 ° C, the water concentration is 600 ppm).

EXAMPLE 6

500 kg of whole Jatropha curcas seeds were placed in a mechanical screw press and 125 kg of dark brown oil containing 3.2% (w / w) FFA was obtained. A portion of 105 kg (3.86 mol) of the oil was placed in a two-liter stainless steel vessel with a paddle stirrer (100 rpm) and 2.7 l of a 5N NaN solution (13.5 mol) was added to the oil with stirring (1.16 mol) equivalent of free fatty acids) at room temperature for 10 minutes It was stirred for 45 minutes, the saponified mass was filtered through a vacuum Nutch filter and 13.0 kg of soap and 92.5 kg of oil containing 0.26% (w / w) FFA were obtained. In a separate vessel, 18.3 kg of a solution of KOH in methanol was prepared by adding 1.5 kg of KOH in 16.8 kg (1.64 mol equivalents per neutralized oil) of MeOH with stirring for 15 minutes. This solution was added to the oil with stirring for 20 minutes at room temperature using a metering pump, and the contents were stirred for another 1 hour under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, and then the glycerol layer was separated from the bottom of the vessel and weighed (17.7 kg). The ether layer was again transesterified with an additional amount of methanol KOH prepared as described above from 5.85 kg of MeOH (0.57 mol. Equiv. Based on neutralized oil) and 0.5 kg of KOH. No more glycerol was separated. The ether layer of biodiesel was then treated with 12.6 kg of glycerol with stirring and allowed to stand for 90 minutes to complete the separation of the layers of glycerol and biodiesel. The mass of the separated glycerol layer was 20.2 kg. The ether layer with biodiesel was washed three times with water (90 L each time) and 0.9 g of BHT antioxidant was added. Moreover, the water content in biodiesel, determined by the Fisher method, was 0.18% (1800 ppm). Compressed air was passed through silica gel, and the resulting dry air was used to purge biodiesel for 3 hours. The biodiesel mass was 90 kg (yield 97.3% based on neutralized oil). Biodiesel analysis showed that it contains 0.262% FFA, 0.048% of total glycerol, 0.009% of free glycerol and 450 ppm. water. A sample of this portion was sent for detailed analysis, the results are shown in the table below.

Analysis of the fatty acid methyl ester of Example 3 ^a View Transparent golden
yellow liquid DIN value Real value Density @ 15 ° C ISO 3675 kg / m ³ 860-990 880.0 Dirty tv substances mg / kg <24 four Acid number DIN 51 558-1 mg KOH / g <0.5 0.1 Viscosity at 40 ° C ISO 3104 mm ² / s 3,5-5,0 4.34 Iodine number DIN 53241-1- plaster Gi _2/100 g <120 96 Ash ISO 3987 g / 100 g <0.02 <0.01 Water content EN ISO 12937 mg / kg <500 450 Flash point DIN EN 22719 ° C > 101 160 Cetane number ^a - > 51 54.5 Total calorific value ^b D4809 kcal / kg 9562 Monoglycerides EN 14 105 g / 100g <0.8 0.15 Diglycerides EN 14 105 g / 100g <0.2 <0.02 Triglycerides EN 14 105 g / 100g <0.2 <0.02 Free glycerol EN 14 105 g / 100g <0.2 <0.02 Summarn. glycerol EN 14 105 g / 100g <0.25 0.04 Methanol prEN 14110 g / 100g <0.2 <0.02 Ether content prEN 14103 g / 100g - 98.5 Sodium mg / kg <0.5 total 0.2 Potassium mg / kg Na + Ka 0.2 Magnesium mg / kg - <0.5 Calcium mg / kg - <0.5 Phosphorus mg / kg <10 <1 ^a Analysis conducted by DaimlerChrysler AG, Germany
^b Analysis conducted by Reliance Industries Ltd., India

From this example, it is seen that the fatty acid methyl ester from the oil squeezed from whole seeds of Jatropha curcas can be processed according to the method of the present invention with 2.2 equiv. methanol and 2.2% (wt./wt.) KOH and get Bl00 biodiesel with a yield of 97.2%, all parameters of which meet the technical specifications of EN 14214, and most parameters have values significantly lower than the specified limit values. It can also be seen that this invention overcomes the important limitation of the prior art regarding the P content of biodiesel.

EXAMPLE 7

115.8 kg of neutralized oil containing 0.26% (w / w) residual FFA was placed in a two hundred liter stainless steel vessel with a paddle stirrer (100 rpm). 15.5 kg of a methanol solution of KOH were prepared in a separate vessel, adding 1.305 kg of KOH in 14.2 kg of MeOH (1.12 mol. Equiv. Calculated on neutralized oil) with stirring for 15 minutes. This solution was added to the oil with stirring for 30 minutes at room temperature using a metering pump and the contents were stirred for another 1 hour under normal conditions. Then the stirring was stopped and the contents were allowed to stand for 1 h, after which the glycerol layer was separated from the bottom of the vessel and weighed (17.28 kg). The ether layer was again transesterified with an additional amount of methanol KOH, prepared as described above, from 6.24 kg of MeOH (0.5 mol equivalents per neutralized oil) and 0.56 kg of KOH. Separated another 4.58 kg of glycerol. The ether layer of biodiesel was then treated with 7.44 kg of glycerol with stirring for 5 minutes and allowed to stand for 90 minutes to completely separate the layers of glycerol and biodiesel. The mass of the separated glycerol layer was 11.3 kg. The biodiesel ether layer was washed three times with demineralized water (<50 ppm TDS) (3 × 70 L) and 1.1 g of BHT antioxidant was added. Compressed air was passed through silica gel and the resulting dry air was used to purge biodiesel for 3 hours, after which the water content dropped to 460 ppm. The biodiesel mass was 109.4 kg (yield 94.5% based on neutralized oil). Biodiesel contained 0.25% FFA, 0.11% total glycerol, and 0.02% free glycerol.

EXAMPLE 8

80.1 kg of oil containing 0.36% (w / w) residual FFA was placed in the reactor. 14.46 kg of methanol KOH solution was prepared in a separate vessel by adding 1.2 kg of KOH in 13.26 kg of MeOH (1.5 mol equivalents per neutralized oil) with stirring for 15 minutes. This solution was added to the oil with stirring for 30 minutes at room temperature using a metering pump, and the contents were stirred for another 1 hour under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, after which the glycerol layer was separated from the bottom of the vessel and weighed (14.2 kg). The ether layer was again transesterified with an additional amount of methanol KOH, prepared as described above, from 6.24 kg of MeOH (0.7 mol. Equiv. Based on neutralized oil) and 0.5 kg of KOH. Separated another 3.2 kg of glycerol. The ether layer of biodiesel was then treated with 10.2 kg of glycerol with stirring for 5 minutes and allowed to stand for 90 minutes to completely separate the layers of glycerol and biodiesel. The mass of the separated glycerol layer was 18.5 kg. The ether layer of the biodiesel was washed three times with demineralized water (<50 ppm TDS) (3 × 70 L) and 0.80 g of BHT antioxidant was added. Compressed air was passed through silica gel and the resulting dry air was used to purge biodiesel for 3 hours, after which the water content decreased to 0.048% (480 ppm). The mass of biodiesel was 76.2 kg with a volume of 87 liters. Biodiesel contained 0.36% FFA. The content of total glycerol and free glycerol was below the limits of determination.

Examples 5-7 show that biodiesel that meets the specifications of EN14214 can be obtained by transesterification in two stages with total amounts of methanol and KOH in the range of 1.62-2.20 equiv. and 1.6% -2.2%, respectively. As in the case of example 4 (methods C and D), the FFA content in biodiesel is the same as in neutralized oil. However, with reduced amounts of methanol and catalyst, a sharp decrease in yield is observed. The examples also show that if the amounts of methanol and KOH used in the first step are> 1.62 eq. and 1.6%, then in the second stage of transesterification no appreciable amount of glycerol layer is formed. Therefore, we can assume that in order to obtain biodiesel that meets the requirements of EN14214, one-stage transesterification is also possible in the presence of optimal amounts of methanol and KOH.

EXAMPLE 9

83 kg of neutralized Jatropha oil containing 0.31% (w / w) residual FFA was placed in the reactor. 17.45 kg of methanol KOH solution was prepared in a separate vessel by adding 1.45 kg of KOH in 16.0 kg of MeOH (1.74 mol. Equiv. Calculated as oil) with stirring for 15 minutes. This solution was added to the oil with stirring for 30 minutes at room temperature using a metering pump, and the contents were mixed for another 1.25 hours under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, after which the glycerol layer was separated from the bottom of the vessel and weighed (17.4 kg). A 250 ml aliquot was taken from the methyl ether layer and shaken with water in a separatory funnel. It was seen that a clear separation into layers is difficult. The remaining methyl ether layer was treated with 6.35 kg of glycerol with stirring for a minute and allowed to stand for 90 minutes to completely separate the layers of glycerol and ether. The mass of the separated glycerol layer was 7.55 kg. The ether layer was washed three times with water (3 × 70 L) containing <50 ppm. TDS Then 0.8 g of BHT antioxidant was added to the methyl ester and the contents were purged with dry air for 3 hours. 78 kg biodiesel (yield 94.0% w / w) contained 0.31% FFA, 0.15% total glycerol , <0.01% free glycerol and 450 ppm water.

EXAMPLE 10

A portion of 105 kg of oil squeezed from Jatropha curcas seeds obtained from the Udaipur region of Rajasthan, India, containing 1.67% (w / w) FFA, was loaded into a two hundred liter stainless steel vessel with a paddle stirrer (100 rpm) and 1 L of a 5N NaOH solution (0.82 mol. equiv. FFA) was added to the oil with stirring at room temperature for 15 minutes. Stirring was continued for 60 minutes, the saponified mass was filtered by centrifuge and 4.5 kg of soap and 102.2 kg of oil containing 0.33% (w / w) residual FFA were obtained. In a separate vessel, 21.2 kg of a methanol solution of KOH was prepared by adding 1.78 kg of KOH in 19.4 kg of MeOH (1.74 mol equivalents based on neutralized oil) with stirring for 15 minutes. This solution was added to the oil with stirring for 30 minutes at room temperature using a metering pump, and the contents were stirred for an additional 1.25 hours under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, after which the glycerol layer was separated from the bottom of the vessel and weighed (22.84 kg). The crude ether layer was washed with three portions of glycerol of 1.08 kg, 1 kg and 1.06 kg, respectively, with stirring for 5 minutes and allowed to stand for 60 minutes to completely separate the layers of glycerol and biodiesel. The mass of the separated layers of glycerol was 2.44 kg, 1.24 kg and 1.28 kg, respectively. The methyl ether layer was washed with three portions of water (3 × 70 L) with <50 ppm. TDS The COD values in three consecutive portions of water amounted to 30,400 ppm, 754 ppm. and 257 ppm respectively. 1 g of BHT antioxidant was added and the methyl ether was purged with dry air. It was found that the product weighing 96.1 kg (yield 94.1% based on neutralized oil) contained 0.32% FFA, 0.156% total glycerol, 0.01% free glycerol and 480 ppm. water.

EXAMPLE 11

A portion of 527 kg of Jatropha Curcas seeds obtained from the Udaipur region of Rajasthan, India, was ground and 125 kg of oil containing 1.78% (w / w) FFA were obtained. A portion of 106 kg of oil was placed in a two hundred-liter stainless steel vessel with a paddle stirrer (100 rpm) and 1.1 l of 5N NaOH solution (0.82 mol. Equiv. FFA) was added to the oil at room temperature for 15 minutes . Stirring was continued for 60 minutes, the saponified mass was filtered by centrifuge and 5.15 kg of soap and 102 kg of oil containing 0.31% (w / w) residual FFA were obtained. The neutralized oil contained 0.1% water. In a separate vessel, a methanol solution of KOH was prepared by adding 1.81 kg of KOH (1.77% based on neutralized oil) to 19.7 kg of MeOH (1.75 equivalent of neutralized oil) with stirring for 15 minutes, and processed 1 kg anhydrous sodium sulfate. The resulting solution, weighing 21.2 kg, was added to the oil with stirring for 30 minutes at room temperature using a metering pump, and the contents were mixed for another 1.25 hours under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, after which the glycerol layer was separated from the bottom of the vessel and weighed (21.15 kg). The methyl ether layer was then washed with three portions of glycerol of 1.15 kg, 1.00 kg and 1.00 kg, respectively, with stirring for 5 minutes and allowed to stand for 60 minutes to completely separate the layers of glycerol and biodiesel. The masses of the separated glycerol layers were 2.06 kg, 1.55 kg and 1.05 kg, respectively. The methyl ether layer was washed with two portions of water (2 × 70 L) containing <50 ppm. TDS, then 1 g of BHT antioxidant was added and the product was dried by blowing dry air. It was found that biodiesel weighing 98.05 kg (yield 96.13% based on neutralized oil) contained 0.31% FFA, 0.16% total glycerol, 0.01% free glycerol and 450 ppm. water.

Examples 8-10 show that B100 biodiesel with a total glycerol content <0.16% can be obtained by single-stage transesterification using 1.74 equiv. methanol and 1.74% KOH. In addition, these examples show that since the mass of the glycerol layer obtained is exactly the same as the mass of methanol KOH taken for transesterification, little methanol and catalyst remain in the crude methyl ether, so that even with smaller amounts of added glycerol, impurities can be removed from layer of methyl ether. In addition, Example 10 shows that by removing water from the neutralized oil and treating the KOH methanol solution with anhydrous sodium sulfate before transesterification, it is possible to reduce the content of impurities in the glycerol layer and at the same time increase the yield of fatty acid methyl ester from about 94% to 96%.

EXAMPLE 12

The separated glycerol layers from Example 7 were mixed, 2 kg of a total of 35.9 kg containing 58 g of potassium hydroxide (catalyst) was placed in a five-liter round bottom flask immersed in a cold water bath, and treated with 50 g of 98% sulfuric acid ( 36M H ₂ SO ₄ ), making sure that the temperature does not rise above 30 ° C. The mixture was stirred for about 15 minutes. The solid crystals were filtered off, washed with 400 g of methanol, dried at 100 ° C for one hour, and 78.7 g (88.4% yield) of potassium sulfate (K ₂ O content = 51.8%) were obtained, which can be used as potassium fertilizers. 1.88 kg of methanol-glycerol filtrate was placed in a distillation unit. Upon distillation, 328 g of methanol and 1.563 kg of glycerol were obtained.

EXAMPLE 13

37 kg of the separated glycerol layer formed during the preparation of biodiesel in Example 5 above, containing 1.69 kg of potassium hydroxide (catalyst), was placed in a fifty-liter vessel and treated with 1.315 kg of 98% sulfuric acid (36M H ₂ SO ₄ ) at room temperature. The mixture was stirred for about 5 minutes. The solid crystals were filtered off, washed with 4.5 kg of methanol, dried at 100 ° C for one hour and obtained 2.48 kg (yield 94.4% based on KOH) of potassium sulfate (K ₂ O content = 47.3%), used as potash fertilizer.

EXAMPLE 14

We analyzed a portion of 2.5 l of the glycerol layer formed upon receipt of biodiesel, and found that it contains 101.3 g of spent KOH catalyst. It was neutralized by bubbling SO ₃ . The mass was filtered, washed, dried and received 147.2 g of potassium sulfate (yield 93.5%).

EXAMPLE 15

A portion of 1.43 kg of neutralized oil containing 0.267% (w / w) residual FFA was further transesterified in a three-necked glass vessel with an anchor type stirrer. 198.1 g of methanol solution was prepared in a separate vessel by adding 16.6 g of KOH in 181.5 g of MeOH (1.15 mol. Equiv. Based on neutralized oil) with stirring for 15 minutes. This solution was added to the oil with stirring at a speed of 200 rpm for 20 minutes at room temperature and the contents were stirred for another 1 hour under normal conditions. Then the stirring was stopped and the contents were allowed to settle for 1 h, after which the glycerol layer was separated from the bottom of the vessel and weighed (207.5 g). The extract was then transesterified for 1 h with methanol KOH prepared from 75.5 g of MeOH (0.5 mol equivalents based on neutralized oil) and 7.0 g of KOH, as described above. After stirring was stopped, 80.2 g of the glycerol layer were separated and the contents allowed to stand for one hour. Crude methyl ether was placed in a separatory funnel and treated with two portions of glycerol - 100 g and 41.9 g, respectively - with stirring for a minute. After adding the first portion and settling for 10 minutes, 110.4 g of the glycerol layer were obtained, and in the second case, after settling for 1.5 hours, 75.6 g were obtained, i.e. total 186.3 g. The ether layer of biodiesel was washed three times with demineralized water (<50 ppm TDS) (3 × 1 L). Compressed air was passed through silica gel and the resulting dry air was used to purge biodiesel for 1 h, as a result of which the water content decreased to 0.046% (460 ppm). The mass of biodiesel was 1.35 kg with a volume of 1.54 liters.

It was determined that 469.3 g of the separated glycerol layer formed upon receipt of biodiesel contained 3.79% (w / w) potassium hydroxide (catalyst). It was placed in a two-liter vessel and treated with 15.3 g of 98% sulfuric acid (36M H ₂ SO ₄ ) at room temperature. The mixture was stirred for about 15 minutes. The solid crystals were filtered off, washed with 300 g of methanol and dried at 100 ° C for one hour to obtain 23.92 g (87.3% yield based on KOH and 91.6% yield based on H ₂ SO ₄ ) potassium sulfate ( the content of K ₂ O = 51.1%)) used as potash fertilizer. The filtrate containing methanol and glycerin was distilled in vacuo and 69 g of methanol (at 40 ° C and a pressure of 570 mm Hg) and 250.9 g of glycerol (at 250 ° C and 570 mm Hg) were isolated. A total of 73% methanol and 86% glycerol were isolated.

Examples 11-14 demonstrate an energy-efficient way of separating spent catalyst and simultaneously isolating methanol and pure glycerol.

EXAMPLE 16

20 kg of soap containing approximately 20% (w / w) oil was obtained by neutralizing Jatropha oils from different batches. He was placed in a vessel with a shirt and a stirrer. 5 L of a 10N NaOH solution was added with stirring for 10 min and heated to 70-80 ° C. The resulting suspension was poured into a bath and allowed to cool to room temperature. The soap had good washing properties and was suitable for making bar soap.

EXAMPLE 17

You can refer to the article “Commodity exchange on the way to clean biodiesel”, AS Anand (Times News Network, April 5, 2004), which indicates the intention to switch to using pure biodiesel. The specified biodiesel obtained by the applicants according to the methods of examples 5-10. You can also refer to the article entitled “ Biodiesel Comes Between the Commodity Exchange and Farmers, ” published in The Financial Express of April 22, 2004 (New Delhi Edition), which reviews successful tests of a moving vehicle using approximately 800 liters of pure biodiesel.

EXAMPLE 18

550 l of pure biodiesel produced by the methods of examples 5-10 were tested on a Powrin brand 8 HP stationary engine with the following indicators: inner bore 114.3 mm; piston stroke 139.7 mm; engine displacement of 1.4330 l; compression ratio 19: 1; rpm, 850. Mileage was ten 16-hour cycles. The engine could run smoothly with biodiesel without any modification.

The advantages of the present invention are:

1. The invention allows to obtain biodiesel of the desired specification from Jatropha oil, squeezed directly from whole seeds.

2. The developed method allows to obtain biodiesel of the desired brand, even by one-stage transesterification without any purification.

3. The method eliminates the need to expose Jatropha oil and biodiesel to heating or cooling, which is beneficial both in terms of energy efficiency and product quality.

4. The invention includes a simple installation.

5. The yield of biodiesel according to the method of the present invention is> 96%.

6. The method is environmentally friendly with a low level of effluent and the allocation of useful by-products.

Claims (21)

1. A method of producing fatty acid methyl ester (biodiesel) from an oil containing triglycerides and obtained from plants, which comprises (i) squeezing the oil from whole seeds and separating the cake for use as an organic fertilizer, (ii) neutralizing the alkali contained in the oil excess free fatty acid, and separating the soap residue, (iii) adding an antioxidant and purging the oil with dry air to reduce the water content, (iv) treating the oil with an appropriate amount of KOH methanol solution dried over anhydrous sodium sulfate, (v) separating the glycerol layer formed during the reaction, (vi) treating the fatty acid methyl ester layer with glycerol in two steps to further reduce the content of methanol, catalyst and other impurities in the fatty acid methyl ester layer, (vii) separating glycerol, (viii) washing the layer of fatty acid methyl ester with water in two steps to minimize impurities, (ix) separating the wash water, (x) adding an additional amount of antioxidant to the fatty acid methyl ester and selling dry air to minimize water content, (xi) combining the glycerol layers and treatment with SO _x or flue gas to convert the spent KOH catalyst to K ₂ SO ₃ or K ₂ CO _3, respectively, (xii) setting the pH to about 7 and distillation methanol from the glycerol layer, (xiii) hot centrifuging the remaining mass to separate the potassium salt from glycerol, (xiv) washing the salt to remove impurities, (xv) separating the necessary amount of crude glycerol to wash the layer of fatty acid methyl ester in the next portion and also for other applications where the crude glycerol is directly used, and (xvi) distilling the remaining crude glycerol with a low water content to obtain purified glycerol. 2. The method according to claim 1, in which the oil containing triglycerides is obtained from plants and more specifically from Jatropha Curcas. 3. The method according to claims 1 and 2, in which the yield of the obtained biodiesel is maintained in the range of 94-98%, and the quality of the biodiesel meets the technical conditions of EN14214. 4. The method according to claims 1 and 2, in which the average yield of oil during mechanical extraction from whole seeds of Jatropha Curcas used in the present invention is 20-30% (wt./wt.). 5. The method according to claims 1 and 2, in which the cake containing 5-10% oil is crushed. 6. The method according to claims 1 and 2, in which the content of free fatty acid in freshly squeezed oil is 1.5-10.0% (wt./wt.). 7. The method according to claims 1 and 2, in which the oil is treated under normal conditions with 5N caustic soda solution, the amount of alkali being 0.7-1.0 eq. (based on FFA) depending on the initial content of FFA in the oil to obtain a neutralized oil containing 0.25-0.35% (wt./wt.) FFA. 8. The method according to claims 1 and 2, in which the neutralization method allows to obtain oil with improved color, transparency and fluidity, which, in turn, provide biodiesel golden yellow and high transparency. 9. The method according to claims 1 and 2, in which the soap residue containing 10-30% of residual oil is treated with an additional amount of alkali to prepare bar soap. 10. The method according to claims 1 and 2, in which the water content in the neutralized oil is reduced from 0.05-0.2 to 0.005-0.01% by blowing with dry air after adding a suitable antioxidant at a concentration of 30-50 ppm. 11. The method according to claims 1 and 2, in which the methanol solution of KOH used for transesterification is treated with a stoichiometric amount (with respect to KOH) of anhydrous sodium sulfate to absorb water, which can be formed as a result of the reaction of alkali with alcohol. 12. The method according to claims 1 and 2, in which the removal of water from the neutralized oil and methanol KOH increases the yield of methyl ether by 1-5% and at the same time reduces the yield of by-products that are difficult to process. 13. The method according to claims 1 and 2, in which the oil is subjected to transesterification with methanol KOH in two stages and preferably in one stage using 1.5-2 equiv. methanol and 1.5-2% (w / w) alkali and more specifically KOH with respect to the neutralized oil. 14. The method according to claims 1 and 2, in which the layer of crude methyl ether after removal of the glycerol layer is additionally treated with 1-10% amount of glycerol to remove remaining impurities in the layer of methyl ether and prevent its entrainment with the aqueous stream when washing the layer of methyl ether two portions of water with <50 ppm dissolved salts and, more importantly, preventing undesired hydrolysis of the ester. 15. The method according to claims 1 and 2, in which part of the first portion of the wash water, which is usually 0.5 ÷ 1.0 l per liter of biodiesel and contains 25000-35000 ppm substances that determine the chemical need for oxygen, are used to prepare the liquor required at the stage of neutralization, and also for the preparation of bulk soap from the soap residue, and the rest is treated before discharge. 16. The method according to claims 1 and 2, in which the second of two portions of washing water, which contains 500-2000 ppm substances that determine the chemical need for oxygen, are used for the first water wash of the next portion. 17. The method according to claims 1 and 2, in which the obtained methyl ether is treated with 5-50 ppm. antioxidant and more specifically bottled hydroxytoluene and purged with dry air to reduce the water content to <500 ppm. 18. The method according to claims 1 and 2, in which the main part of the KOH catalyst is collected in a glycerol layer, which can be treated with a stoichiometric amount of concentrated sulfuric acid, SO _x vapors or flue gases to convert the spent catalyst into a useful potassium fertilizer, which can be directly used in agriculture, with a yield of 95-100%. 19. The method according to claims 1 and 2, in which methanol is isolated from the glycerol layer by distillation with a yield of 70-90%. 20. The method according to claims 1 and 2, in which a portion of the crude glycerol after removal of the spent alkaline catalyst and methanol can be reused for washing the crude methyl ether from the next portion. 21. The method according to claims 1 and 2, in which the crude glycerin, separated from biodiesel, is distilled to obtain purified glycerol with a yield of 85-95%.