WO2010043013A2

WO2010043013A2 - A method for the production of biodiesel fuel

Info

Publication number: WO2010043013A2
Application number: PCT/BR2009/000324
Authority: WO
Inventors: Oswaldo Theodoro Peckolt; Claudio Costa Neto
Original assignee: Oswaldo Theodoro Peckolt; Claudio Costa Neto
Priority date: 2008-10-17
Filing date: 2009-10-16
Publication date: 2010-04-22
Also published as: BRPI0804354A2; WO2010043013A3

Abstract

The present invention is related to a method for the production of biodiesel fuel, comprised by methyl esters of fatty acids, directly from the conversion of the triglycerides present in the vegetable or animal fats, or in other alternative sources of oils or fats, into the methyl esters of the respective acids, by cleaving between the consecutive carbon atoms of the glycerol molecule of the triglyceride, either by a chemical-catalytic route, or by a biotechnological-enzymatic route.

Description

"A METHOD FOR THE PRODUCTION OF BIODIESEL FUEL"

TECHNICAL FIELD

The present invention is related to a method for the production of biodiesel fuels, comprised by methyl esters of fatty acids, directly from triglycerides present in vegetable or animal fat, or in other alternative forms of oils and fats, irrespective of the nature and origin thereof. More specifically, in the method according to the present invention, the triglycerides are directly converted into the respective acid methyl esters, by cleaving between consecutive carbon atoms of the glycerol molecule of the triglyceride.

BACKGROUND OF THE INVENTION

The oils and fats are hydrophobic, water-insoluble substances, formed by the union of 1 mole of glycol and 3 moles of fatty acids, commonly known as triglycerides [in Portuguese, "triglicerides" or "triglicerideos", among other variants].

The biodiesel, which is comprised of fatty acids, is an alternative fuel, which is biodegradable, obtained from renewable biological sources, such as particularly vegetable oils or animal fats.

The biodiesel has been the object of researches since the decade of the 1980's in France and slightly later in Germany. In France, the methyl esters of vegetable oils were already produced and tested in various types of engines, at that time by the French Petroleum Institute - Institut Francais du Petrole -

EFP. The IFP developed two processes for the production of methyl esters and two for the production of ethyl esters - cf: Gateau, P., Guibet J. C, Hillion G. and Stern R., Revue du Institut Francais du Petrole [Review of the French Petroleum Institute] vol. 40, no. 4, Juillet-Aout [July-August] 1985.

Commonly, the biodiesel is obtained from the chemical reaction of the triglycerides, originated from oils or fats, of animal or vegetable origin, with a methylic alcohol (methanol) or an ethylic alcohol (ethanol) in the presence of a catalyst, thereby producing a mixture of esters and glycerol. This reaction is quite well known and is denominated as transesterification.

In the production of biodiesel, the vegetable oils may be obtained from a series of oleaginous plants such as soy, sunflower, canola, rapeseed, castor-bean ["mamona"], peanut, palm oil ["dende"], cotton and various palm trees. The use of animal fat as raw material for the production of biodiesel is much less common.

Compared to the diesel oil originating from petroleum (petrodiesel), the biodiesel is an environmentally friendly fuel, since it reduces the emissions of pollutants and particulate materials into the atmosphere, in addition to being biodegradable and non-toxic. Due to being a fuel which usually originates from vegetable sources, it does not contribute to the increase of the amount of carbon dioxide present in the atmosphere, since it results from the recycling of atmospheric carbon dioxide by the plants that produce the triglycerides and the sugars intended to be fermented to produce ethyl alcohol. Due to exhibiting physical and chemical properties that are similar to those of the petrodiesel, in addition to behaving in an identical manner in the so-called OTTO cycle engines, the biodiesel may be used directly in the engine, without requiring any significant mechanical adaptations or maintenance expenditures.

There are four classic forms of use of the triglycerides of vegetable origin, according to Gateau, P., Guibet J. C, Hillion G. and Stern R. Revue du Institut Francais du Petrole [Review of the French Petroleum Institute], vol. 40, no. 4, Juillet-Aoύt [July- August], 1985: a) direct use of the vegetable oils; b) microemulsions; c) thermal cracking (pyrolysis); and d) transesterification.

The direct use of the vegetable oils as fuels involves a series of disadvantages, such as high viscosity, low volatility and the presence of free fatty acids. The main problems associated with the direct use of the vegetable oils as fuels are incomplete combustion, causing the formation of carbon deposits in the engine, and the thickening of the oil due to the polymerization of the unsaturated fatty acids.

The problem associated with the high viscosity of the vegetable oils, however, may be remedied by the preparation of microemulsions, using common alcohols as surfactants (particularly methanol and ethanol). The use of such emulsions is limited by the instability at high temperatures and by the tendency of the alcohol to absorb moisture from the air, requiring special storage tanks in order to keep the fuel dry. That type of fuel was denominated HydroFuel and was the object of much research by the end of the 1960's decade, and during the decade of the 1970's. (Globus, A. R., National Petroleum Refiners Association National Fuels and Lubricants Meeting Sept. 11-12, 1975, Houston, Texas) and in the beginning of the nineteen-eighties.

The thermal cracking of the triglycerides, in turn, leads to the formation of paraffins, olefins and unsaturated methyl esters which composition is similar to that of the petroleum byproducts. The higher is the pyrolysis temperature, the greater is the yield of light hydrocarbons. That process normally causes the formation of more gasoline than diesel fuel, and practically no production of biodiesel (methyl ester of fatty acid). Furthermore, the elimination of oxygen during the thermal cracking removes in part the environmental benefits otherwise derived from the use of an oxygenated fuel, such as the biodiesel.

The process currently commonly used for obtaining biodiesel consists in the transesterification of the triglycerides with an alcohol, forming esters, that constitute the fuel, and glycerol, according to the following reaction:

triglyceride alcohol glycerol esters

In the process of transesterification there are used alcohols, particularly methanols and ethanols. The methanol is the one that is more utilized outside of Brazil, due to its low cost and high reactivity. Even so, the use of any alcohol implies a substantial increase in the cost of production of biodiesel in the need of acquisition thereof. Normally, the alcohol is used in excess in order to dislocate the equilibrium towards a maximum ester yield. The reaction may be catalyzed using bases (NaOH, KOH, carbonates or alkoxides), acids (HCl, H and sulfonic acids) or enzymes (lipases). The homogeneous basic catalysis is the one that is most employed commercially.

After the transesteriflcation there is obtained a mixture of esters, glycerol, alcohol, catalyst and tri-, di- and monoglycerides. The excess alcohol is recovered by distillation and the glycerol is separated by decantation. The ester is purified by washing and distillation. The transesteriflcation produces as a result a significant reduction of viscosity, thereby bringing the same into conformity with the specification for diesel oil, and improving the atomization of the fuel.

The transesteriflcation catalyzed by bases requires that the free fatty acids content be low and that the triglycerides and the alcohol being employed be anhydrous. The presence of free acids requires a larger amount of catalyst, in order to neutralize the same. The water, in turn, causes saponification, reducing the performance of esters. The formation of soap causes an increase of viscosity, formation of gel and solubilization of the oil or fat in the glycerol, thereby rendering difficult the separation of the esters. In patent No. US 2,383,601 there is recommended the use of anhydrous alcohol when the free fatty acids content is high. In the presence of water or free fatty acids in the triglyceride, the transesterification should be conducted by means of acid catalysis, which normally results in a reduction in the yield of esters, that are entrained to the aqueous phase by the salts formed in the neutralization of the fatty acids.

In patent No. US 4,695,411 (September 1987), Stern et al. proposed a method in three steps, which allows the use of oils or fats with up to 50% acidity and hydrated alcohols without compromising the yield of the esters. The first step consists in a transesterification of the triglyceride with ethanol, containing between 4 and 50% by weight of water, and an acid catalyst, which may be soluble or insoluble, preferably sulfonic acid. The reaction is conducted between 80 and 130 deg. C and allows conversions of more than 75% in ethyl esters. In the second step, upon the removal of the aqueous phase containing the glycerol, the acidity of the ester phase is reduced down to about 2% by esterification in the presence of a desiccant agent for the alcohol, such as a molecular sieve. The last step is the transesterification of that ester phase with basic catalysts (NaOH, KOH, lithium compounds or anion-exchange resins), at a temperature of between 20 and 100 deg. C. The thus obtained ester contains only traces of alkaline salts, glycerol and alcohol, with a purity of more than 97%.

Kawahara and Ono, in patent No. US 4,164,506, also pointed out the importance of a pre-esterification step for the removal of free fatty acid residues and impurities, such as phospholipids and polypeptides, from the oils and fats. OBJECTS OF THE INVENTION

The object of the present invention consists in the provision of a process for the production of biodiesel from the direct conversion of triglycerides, present in animal or vegetable fats, or in other alternative sources of oils and fats, into methyl esters of fatty acids.

More specifically, the object of the present invention consists in the provision of a method capable of transforming the fats and oils of vegetable or animal origin into methyl esters by cleaving the molecule of triglycerides between the carbon atoms of the glycerol portion thereof.

Furthermore, an important object of the present invention consists in the development of a process for the production of biodiesel that might not generate glycerol as a co-product or a by-product, thereby eliminating the additional concern of finding a destination for the undesired glycerol.

One other object of the present invention is the development of a process of production of biodiesel fuel of high quality, feasible at the industrial level, dispensing the use of alcohol for the production of fatty acid esters, in order to afford a reduction of costs related to the acquisition of raw materials.

SUMMARIZED DESCRIPTION OF THE INVENTION

The present invention consists in a process for the production of biodiesel, comprised by methyl esters of fatty acids, from the cleaving of the molecules of triglycerides, present in vegetable or animal fats, or in other alternative sources of oils and fats, according to the reaction below: catalysts + specific hydrogenating

In the process according to the present invention, the triglycerides are directly converted into the methyl esters of the respective acids that contain one carbon atom, to form the methyl ester, by means of use of special catalysts (chemical route) or enzymatic catalysts, by means of a process of cleaving between two consecutive carbons in its glycerol portion (biotechnological/fermentation route).

It is, therefore, a catalytic process for the production of methyl esters of fatty acids directly from triglycerides present in oils or fats, using solid catalysts comprising special metals in their composition (such as, for example, metals of periods 5 and 6, either or not in association, on various supports such as, for example, zeolites and others), in addition to hydrogenating agents, or enzymatic catalysts, either or not in the presence of hydrogenating agents.

DESCRIPTION OF THE FIGURE

Figure 1 is a schematic diagram of the process for production of biodiesel fuel, according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

The process that constitutes the object of the present invention consists in a catalytic process for the production of biodiesel fuel from triglycerides that are present in vegetable or animal fats, or in other alternative sources of oils and fats, under conditions that may vary in terms of temperature, pressure, residence time and concentration of reactants, for the provision of an efficient transformation of the triglycerides into methyl esters of fatty acids. For example, the temperature may vary from ambient temperature to 200 deg. C and the pressure may vary from ambient pressure to 100 atmospheres, according to the catalysts and the sources of triglycerides that are used.

If the source of oil or fat is not refined and contains free fatty acids as impurities in variable amounts, the free acids may be esterified with an alcohol comprising 1, 2 or 3 carbon atoms, such operation being known as pre- esterification, as described by Kawahara and Ono, in patent No. US 4,164,506. One may also optionally refine the oil used, removing the free fatty acids contained therein.

The present invention comprises the use of solid catalysts containing special metals in the composition thereof (such as, for example, metals of Groups 5 and 6, either or not associated to one another, on various supports such as, for example, zeolites and others) in the process for transforming the fats and oils of vegetable or animal origin into methyl esters by means of chemical cleaving of the triglycerides molecule between the carbon atoms of the glycerol portion thereof. The proposed process makes use of a hydrogenating agent for the formation of the esters, such as water, reduced and hydrogenated derivatives of oxygen, sulfur and phosphorus.

The present invention further refers to the use of enzymatic catalysts or the use of bio-fermentation (microbiological, sludges and other bacteriological media) in a biotechnological process, optionally in the presence of a hydrogenating agent, to transform the fats and oils into methyl esters by cleaving the molecule of triglycerides between the consecutive carbon atoms of the molecule of the glycerol portion thereof.

The transformation processes may be run in batches in a stirred reactor, as well as in fixed-bed continuous reactors, or in tubular reactors with continuous feeding.

In a preferred embodiment of the present invention, the triglycerides are firstly introduced in an emulsifying vessel 1, according to Figure 1, in order to prepare an emulsion with adequate viscosity of the mixture and to maintain an adequate condition of temperature and pressure, however variable depending on the composition of the feedstock, in order to allow and facilitate the subsequent operations.

Subsequently, the emulsion is pumped into the reactor 2, wherein are introduced the fermentative enzymatic substrate, and optionally, the hydrogenating reducing agents, and remains therein for a variable average residence time, which may vary from one to twelve hours, according to the nature of the fats being used. At that point of the process, there may be used one or two reactors in order to warrant the residence times required by the reactions.

From the reactor, the emulsion is sent to a filtration system 3 to separate the enzymatic substrate and other filterable materials, passing thereupon into a decantation vessel 4 to separate the oily phase from the aqueous phase. At that time, there may be employed additives to aid the breakout of any remaining emulsion.

If in the production of the biodiesel, a part of the triglycerides that constitute the oil or fat is not transformed, the biodiesel will be separated from the oil or the fat by means of vacuum fractionated distillation 5. The biodiesel thus produced is then pumped into storage tanks, to be subsequently distributed therefrom, and the untransformed fraction of oil and fat is recycled to the emulsifϊer.

Claims

1. A method for the production of biodiesel fuel, characterized by comprising the direct conversion of triglycerides into methyl esters of the respective acids, by cleaving between the consecutive carbon atoms of the glycerol portion thereof, according to the reaction set out below:

2. A method, as claimed in claim 1, characterized in that the triglycerides originate from vegetable or animal fats, or from other alternative sources of oils and fats.

3. A method, as claimed in claim 1 or claim 2, characterized in that special catalysts and hydrogenating agents are employed for the conversion of the triglycerides by a chemical route.

4. A method, as claimed in claim 3, characterized in that the special catalysts are solid catalysts containing special metals in the composition thereof (such as metals of periods 5 and 6, either or not mutually associated, on various supports, such as zeolites and others).

5. A method, as claimed in claim 1 or claim 2, characterized in that there are used enzymatic catalysts for the conversion of the triglycerides by a biotechnological route.

6. A method, as claimed in claim 1 or claim 2, characterized in that there is employed bio-fermentation (microbiological, sludges and other bacteriological media) for the conversion of the triglycerides by a fermentative route.

7. A method, as claimed in claim 5 or claim 6, characterized in that there is employed thereby a hydrogenating agent.

8. A method, as claimed in claim 3 or claim 7, characterized in that the hydrogenating agent is selected from among water, reduced and hydrogenated derivatives of oxygen, sulfur and phosphorus.

9. A method, as claimed in any one of claims 1 to 8, characterized by being conducted under conditions that may vary in terms of temperature, pressure, residence time and concentration of reactants.

10. A method, as claimed in claim 9, characterized in that the temperature may vary from ambient temperature to 200 deg. C and the pressure may vary from ambient pressure to 100 atmospheres, according to the catalysts and oils used.

11. A method, as claimed in claim 2, characterized in that the source of oil or fat may undergo a pre-esterification with an alcohol comprising

1, 2, or 3 carbon atoms, for esterifying the free fatty acids that may be occasionally present.

12. A method, as claimed in claim 2, characterized in that the oil employed therein is refined in order to remove the free fatty acids occasionally contained therein.

13. A method, as claimed in any one of claims 1 to 12, characterized in that the transformation processes may be carried out in batches in a reactor under stirring, as well as in continuous fixed-bed reactors, or in tubular reactors with continuous feeding.

14. A method, as claimed in claim 1, characterized in that the triglycerides are firstly introduced in an emulsifying vessel for the preparation of an emulsion with adequate viscosity and maintenance of ideal temperature and pressure.

15. A method, as claimed in claim 1, characterized in that the mixture obtained upon the conversion of the triglycerides into methyl esters may be sent to a filtration system, and optionally to a decanting system, for the purpose of separation of phases.

16. A method, as claimed in claim 1, characterized in that the triglycerides that constitute the oil or fat occasionally not converted into methyl esters are recycled, upon having been separated from the biodiesel obtained by vacuum fractionated distillation.