KR20140113656A - Production of biofuel from tobacco plants - Google Patents

Abstract

The present invention relates to a process for the production of biofuels from tobacco biomass comprising solvent extraction of tobacco biomass by methyl acetate or ethyl acetate, transesterification of the oil obtained from the biomass and separation of the biofuel from the transesterified product ≪ / RTI > An excellent yield of the biofuel based on the weight of the biomass is obtained.

Description

TECHNICAL FIELD The present invention relates to a method of producing biofuel from a tobacco plant,

The present invention relates to methods for extracting lipids or oils from plant biomass. In particular, the present invention relates to methods for obtaining biofuels from tobacco plants.

Humans initially have long history of tobacco cultivation as coronary plants and medical plants, and later as premium products. For the most part of recent history, human cigarette consumption is based on the transformation of leaves into smoking products, inhalation powders and chewable products. Recently, alternative uses for cigarettes have been found, for example, for the production of digestive proteins via purification from leaves, to provide pharmacologically useful active ingredients normally present in the leaves and to the leaves or seeds of genetically modified plants It has been proposed as a source of expressed recombinant proteins. Another promising use for tobacco is the supply of fuel for the production of green energy.

Negative results from the environmental point of view of the use of fossil fuels and their limited utility have motivated the discovery of new energy providers. Of these, biofuels are a viable option due to their resuming potential. Biofuels of agricultural origin are usually bioethanol produced from simple (ie, sucrose) or complex (ie, cellulosic) sugar producing plants. Model plants for such production have been identified in sugarcane, corn, wheat, potatoes, tapioca, sugar beets, barley, sorghum and others. Alternatively, the technique may be used to produce fuel oils and biodiesel from oilseed species or non-oil but oil-rich species such as soybean, sunflower, rapeseed, peanut, flax, corn, sesame, palm, palm-kernels, coconuts, Has been developed for production.

As an alternative energy source, biodiesel has several advantages over bioethanol. One advantage is that corn and soybeans, the stock crops, are the dominant starting material for obtaining bioethanol in the United States. In addition, bioethanol production is typically less efficient than biodiesel production. For example, corn ethanol produces only 25% more energy than the energy invested in its production, but biodiesel can produce up to 93% more energy than it needs to be invested in its production. Recently, bioethanol produces more greenhouse gases than biodiesel. Relative to fossil fuels, greenhouse gas emissions were reduced by 12% due to the production and combustion of bioethanol and by 41% by the production and use of biodiesel. Biodiesel also releases less air pollutants per net energy gain than bioethanol (Hill et al., Environmental, Economic and Energy Costs and Benefits of Biodiesel and Ethanol Biofuels ethanol biofuels, Proc Natl Acad Sci USA 2006, 103 (30): 11206-11210).

Biodiesel from tobacco can be an important complement to our country's renewable energy strategy. Current trends focus on extracting oil from tobacco seeds. Global tobacco production is estimated to exceed 4 million hectares, so tobacco seeds could be a viable alternative source of energy. However, tobacco biomass, especially the leaves, has been essentially overlooked for biofuel production. Tobacco plants can produce about 170 tonnes / acres of low cost, high value biomass materials without high labor force requirements, chemical inputs, or geographical restrictions. Tobacco plants have a very large leaf area, small flowering and a ratio of the highest leaf area portion: roots observed among the crops. Like hardwoods, a cigarette will recapture from its stump after the top is cut or it is cut. Upper crops are harvested as many times as possible per year, making it possible to produce very high biomass tonnage. In addition, tobacco grows well in a wide variety of soils in a wide range of environments. Finally, since cigarettes are non-edible plants that can grow well in barren soils, they do not compete with food-producing plants such as corn and soybeans in more fertile soils.

US 2010/0184130 discloses a method of extracting oil from a genetically engineered tobacco plant and its biomass. Genetic manipulation can increase oil deposits in tobacco leaves. This process uses a modified nucleic acid extraction method to retrieve oil from biomass.

US 2009/0234146 discloses oil extraction and transesterification methods from biomass such as plants or algae. Extraction methods include treating the biomass with a co-solvent system comprising at least one polar covalent bond molecule and at least one ionic liquid. The polar covalent molecule may be methyl acetate. The transesterification of the extracted oil is carried out using methanol together with sodium hydroxide as catalyst or methanol with sulfuric acid as catalyst. However, references do not refer to cigarettes.

The present invention aims to increase the efficiency of extracting oils from tobacco biomass and to treat the oil to be suitable for use as biodiesel.

The present invention relates to a process for producing a tobacco product, comprising the steps of extracting a tobacco biomass with a polar organic solvent, separating the extracted oil from the polar organic solvent, transesterifying the extracted oil and separating the biofuel from the reaction mixture To a method for producing biofuel from tobacco biomass.

For illustrative purposes, the principles of the present invention are described with reference to various exemplary implementations. Although specific embodiments of the invention have been described herein with specificity, those of ordinary skill in the art will readily appreciate that the same principles are equally applicable and can be used in other systems and methods. Before describing the disclosed embodiments of the invention in detail, it should be understood that the invention is not limited in its application to the details of any particular embodiment shown. In addition, the terminology used herein is for the purpose of description and is not intended to be limiting. Also, although specific methods have been described with reference to the steps set forth herein in a particular order in many cases, these steps may be performed in any order recognizable to those skilled in the art; Thus, the new method is not limited to any particular arrangement of steps disclosed herein.

It should be noted that, as used herein and in the appended claims, the singular forms "a "," a ", and "include " include a plurality of references unless the context clearly dictates otherwise. In addition, the terms " one ", " one ", "one or more ", and" at least one " The terms "comprising", "containing", "having", and "consisting of" may also be used interchangeably.

In a first aspect, the present invention relates to the production of biofuels from biomass, particularly tobacco. In this aspect, the oil in the tobacco biomass is first extracted from the biomass using a polar organic solvent. The oil is then transesterified to produce fatty acids suitable for use as biofuels.

The term "biomass " as used herein refers to virtually any tobacco plant-derived organic material. This includes all plants, plant organs (i.e., leaves, stems, flowers, roots, etc.), seeds, plant cells (including tissue culture cells), one or more of the above, And include crushed forms of such materials.

Any species or type of tobacco plant may be used for the present invention. Cigarettes with higher oil or lipid content in their biomass are the preferred types of cigarettes for use in the present invention. For example, Navajo tobacco having a relatively high oil content in its biomass is a preferred type of cigarette for use in the present invention. Tobacco plants genetically engineered to have high oil or lipid content in their biomass may be used. Suitable genetically modified tobacco plants include, for example, Andrianov et al., "Tobacco as a production platform for biofuels: Overexpression of Arabidopsis DGAT and LEC2 genes increases accumulation of lipids in green biomass and shifts its composition Tabacco as a production platform for biofuel: overexpression of Arabidopsis DGAT and LEC2 gene amplification and shifts in the composition of lipids in green biomass), " Plant Biotechnol J. , Vol. 8, pp. 277-87 (2009); And US 2010/0184130).

In some embodiments of the present invention, it may be desirable to grow tobacco plants hydroponically in order to grow the tobacco plants at high rates, produce them at higher yields, and / or grow plants throughout the year. Hydroponic cultivation permits the growth of tobacco plants under highly regulated regenerative conditions and promotes efficient harvesting of coarse, filamentous root systems in clean, intact conditions.

One exemplary process for hydroponics of tobacco is as follows. Tobacco seeds are allowed to germinate at or near the surface of a moist plant culture mixture. Suitable conditions are a temperature of about 80 < 0 > C and 60% relative humidity. At about two weeks after seed germination, the seedlings are thinned (removed) leaving them sufficient space for uninterrupted growth of the remaining seedlings at the stage where they are about six inches tall and have about six leaves. When they reach a height of inches, they are usually implanted into pellets of the root system and intact parting material, into the hydroponic device containing the appropriate nutrients and into the means for the aeration (oxygenation) of the nutrient solution. The hydroponic device should also be provided for replenishing dissolved nutrients and should be of sufficient size to accommodate fully grown tobacco plants.

Other suitable growth methods may be used. For example, tobacco can grow in soil supplied with additional growth media such as coconut fibers. Cigarettes can be grown in the greenhouses, preferably in the greenhouse, although outdoor growth can typically be used in a climate suitable for large scale production.

When fully grown, tobacco plants are harvested and oils and / or lipids are extracted from the biomass. Various parts of tobacco plants, including stems, roots, leaves and / or seeds, may be used for the extraction step of the present invention. One skilled in the art will also appreciate that the conditions of the extraction process can be adjusted as needed to optimize it for the type or types of biomass used.

The tobacco biomass can be pretreated prior to the extraction step. The pretreatment steps may include, but are not limited to, one or more of the separation of the biomass from the growth medium, the drying of the biomass, and the physical and mechanical milling of the biomass to increase its surface area. Any method known to those skilled in the art can be used to perform the pre-treatment steps. For example, the biomass can be separated from the growth medium by centrifugation, washed with deionized water to further remove trace amounts of growth medium, dried under vacuum or lyophilized.

The extraction step may be performed by contacting the tobacco biomass with a polar organic solvent to form an extract mixture, thereby extracting the oil and / or lipid components of the biomass into the solvent. Once the desired amount of extraction is complete, the remaining biomass is separated from the extraction mixture.

The polar organic solvent may be selected from methyl acetate and ethyl acetate.

Any suitable amount of organic solvent may be used for the extraction process. For example, an amount of 1-4 grams of organic solvent per gram of biomass may be used. The manner in which the biomass and the polar organic solvent are combined to form the extraction mixture is not important, and thus the biomass may be added to the polar organic solvent or the polar organic solvent may be added to the biomass.

After the extraction mixture has been formed, it may be maintained at ambient temperature, for example at 15-25 DEG C for a sufficient time to extract a substantial portion of the oil or lipids from the tobacco biomass. The extraction mixture may be selectively heated with stirring to a temperature up to the boiling point of the polar organic solvent at the lowest boiling point in the extraction mixture. The extraction period may be from about 1 hour to about 48 hours, depending on whether the steps such as the type and amount of biomass, the type of solvent and other means for promoting heating or extraction are taken. Experts can determine the optimal extraction period by simple experiments. Preferably, the extraction is carried out at a temperature of from about 60 to 65 DEG C for a period of from about 16 to about 48 hours.

In some embodiments, the extraction of the tobacco biomass by the polar organic solvent may be accomplished through application of sonication, shaking, pressure, and / or radiation energy (e.g. microwave, infrared) to increase the speed and efficiency of extraction Can be promoted.

After the extraction is substantially completed based on the economics of the extraction process, as measured on a case-by-case basis, the extraction mixture may be applied to further steps to facilitate separation of the oils extracted from the extraction mixture. For example, centrifugation or filtration can be used to remove the remaining biomass from the extraction mixture. The polar organic solvent may also be removed from the extraction mixture, for example by distillation, such as rotary evaporation or evaporative distillation.

The oil extracted from the tobacco biomass is not optimized for direct use within combustion engines. Thus, the extracted oil is transesterified by the reaction of an oil with a low molecular weight alcohol such as methanol or ethanol in the presence of a catalyst. The transesterification reaction involves the exchange of ester groups, so that the two products: fatty acid esters (an ingredient useful as biodiesel) and glycerin (a valuable by-product traditionally sold for use in soap and other products) . Another byproduct of the reaction is a natural pesticide source that can be isolated and sold separately as another product in the process. The pseudo-compounds and water may be added to the tobacco oil before performing the transesterification step to perform the conventional "alkali refining" step.

The transesterification process can be carried out by mixing the oil with a low molecular weight alcohol such as methanol in the presence of a catalyst to form a reaction mixture. The transesterification may be an acid-catalyzed transesterified or base-catalyzed transesterification step. The catalyst used in the transesterification step may be an acidic catalyst or a basic catalyst. Acid catalyst may be a Bronsted acid or sanil type of acid, H2SO4, HC1, acetyl chloride, BF _3, or the like sulfuric acid. Base catalyst, for example, KOH, NaOH, NaOCH _3, Na ₂ CH ₂ CH _3, guanidine (e.g., 1,5,7- triazol diazabicyclo [4.4.0] des-5-ene (TBD) Etc); And type M (3-hydroxy-2-methyl-4-pyrone) 2 (H ₂ )) ₂ wherein M = Sn, Zn, Pb or Hg. It may be used and the K2CO _3, which ethanol insoluble KHCO ₃ as well as the production of methanol-soluble KOCH _3. In one exemplary embodiment, K ₂ CO ₃ can be used in an amount of 6% of the oil mass for the transesterification process.

The transesterification reaction is typically carried out at a temperature below the boiling point of the alcohol (generally at about 65 DEG C) for at least 30 minutes. When the alcohol and oil components have only a limited miscibility with each other, the two phase reaction mixture may be vigorously stirred and / or the phase transfer catalyst may be used to accelerate the transesterification reaction. In general, acid catalysts require longer transesterification reaction times than base catalysts. In preferred embodiments, acid catalysts are used in combination with higher amounts of alcohols in the transesterification reaction mixture than when base catalysts are used.

Alcohols suitable for use in the transesterification process may be any low molecular weight alcohol preferably having up to four carbon atoms, such as methanol or ethanol. Alcohols are usually used in the reaction mixture in an excess relative to the amount of oil to drive the reaction for fatty acid ester production. The molar ratio of alcohol to transesterifiable oil in the reaction mixture should be at least about 3: 1 to 6: 1. The molar ratio may vary depending on the base used.

When the transesterification reaction mixture generally reaches a point near equilibrium with a conversion of about 80% of the glyceride esters in the reaction mixture relative to the total fatty acid esters, the reaction mixture is allowed to settle for about 12 to 24 hours . The non-polar phases can then be separated and the reaction can be selectively repeated using freshly mixed alcohols and catalysts. After this optional second transesterification step is carried out, the upper non-polar phase (biodiesel phase) is separated and is optionally applied to 9 evaporation or distillation to remove alcohol therefrom.

If desired, conventional fuel additives, such as additives for improving cold resistance, combustion, storage stability, etc., can be added to the resulting biofuel.

Transesterification can be enhanced through the application of sonication, gentle heating, shaking, pressure, and / or radiation energy (e.g., microwave, infrared). For example, the multi-phase reaction mixture may be heated by stirring to a temperature below the boiling point of the alcohol.

The duration of the direct transesterification reaction may be from about 1 hour to 48 hours or more until the direct transesterification reaction is substantially complete. Substantially completed reactions are preferably those in which no significant further increase in the amount or concentration of the product can be obtained by further reaction under the used reaction conditions. After substantial completion of the direct transesterification reaction, the multi-phase reaction mixture may be applied to further processes to promote further separation of the reaction products from each other. For example, the multi-phase reaction mixture may be centrifuged and the components comprising the fatty acid ester product may be removed, for example, by tipping or pipetting into separate vessels.

In some embodiments, the fatty acid ester-containing product may be purified by extraction with a solvent such as a non-polar solvent such as a mixture of hexane or isopropanol and hexane in a molar ratio of 5: 4 after transesterification. Some bases, such as sodium hydroxide, may be added to facilitate this separation. If such solvent extraction is used, the product can be sequestered from the solvent by evaporating the solvent from the product, for example under vacuum.

The fatty acid ester-containing product can be selectively washed with water. In one embodiment, the product is mixed with the same portion of distilled water, allowed to settle for 24 hours, and separated from the water. Anhydrous sodium sulfate or another suitable absorbent material can be used to absorb any residual water from the fatty acid ester-containing product.

The polar organic solvent may optionally be recovered and recycled for use in another direct transesterification reaction or extraction process. Solvent recovery can be accomplished, for example, by centrifugation of the reaction mixture and solvent and rotary evaporation of the slurry to pellet the treated biomass. The polar organic solvent may also be recovered by mechanical filtration if a series of mesh filters with progressively decreasing pore size are used.

The catalyst used in the transesterification step may be an acidic catalyst or a basic catalyst. The acid catalyst may be Bronsted acid. The acid catalyst may be selected from sulfonic acids or sulfuric acids, such as H ₂ SO ₄ , HCl, acetyl chloride, BF ₃ , and the like. Base catalyst, for _{example, KOH, NaOH, NaOCH 3,} Na 2 CH 2 CH 3, guanidine (e.g., l, 5,7- triazol diazabicyclo [4.4.0] des-5-ene (TBD) Etc); And type M (3-hydroxy-2-methyl-4-pyrone) 2 (H ₂ )) ₂ where M = Sn, Zn, Pb or Hg.

In an exemplary embodiment, acetyl chloride may be used as a catalyst in a transesterification reaction with methanol. The catalytic effect is a two-step reaction in which acetyl chloride reacts first with methanol to form methyl acetate dissolved in methanol and gaseous hydrogen chloride. Hydrogen chloride then protonates the carbonyl oxygen of the glyceride and facilitates the exchange of ester groups in the glyceride.

The selection of a particular type of tobacco, a particular set of growth conditions, for example, hydroponic growth, a particular selection of extraction solvents, and a combination of transesterification reactions results in a relatively high yield of biofuel relative to the total plant mass Production. In particular, the use of Navajo tobacco grown under hydroponic conditions, extracted with methyl or ethyl acetate, and applied to transesterification produces a particularly high yield of biofuel relative to the total plant mass.

Biofuel products contain a high percentage of fatty acid esters, which are typically the desired fuel products. Bonds present in fatty acid esters can be measured by infrared analysis. For example, the presence of methanol and double bonds (trans or cis) in the hydrocarbon chain of the biofuel can be measured in this manner. In addition, SP2 carbon atoms can be identified in this way. Infrared analysis may also be used to determine the composition of the methyl esters in the product.

Thin layer chromatography (TLC) can be used to determine the amount of unreacted triglycerides in the composition. The solvent used for the TLX, for example, hexane 85 ml, ether 15 ml and HC ₂ H ₃ O ₂ 1 ml.

The viscometer can be used to measure the relative viscosity. This can be done by comparing the viscosity of the product to the control oil.

The combustion performance of the biofuel can be measured, for example, by using a Bomb Calorimeter.

The following non-limiting embodiments are provided to further illustrate embodiments of the invention. It will be appreciated by those skilled in the art that the techniques disclosed in the following embodiments illustrate the approaches found by the inventors to function well in the practice of the invention and therefore can be considered to constitute embodiments of modes for its practice Should be recognized. It will be apparent, however, to one skilled in the art, that many changes in light of the teachings herein may be made in the specific embodiments disclosed, and still obtain the same or similar results without departing from the scope of the invention.

Example 1 - Extraction

 Tobacco leaves (9.2000 g) were dried prior to oil extraction. The leaves were milled using a commercial grinder at 19,000 rpm. The resulting pulp was placed in porcelain thimble with methyl acetate. The solvent darkened over time after about 3 hours until a medium dark green color was observed. Extraction was continued using a Soxhlet extractor for 2 hours. The tobacco oil was recovered by solvent in a round bottom flask. Distillation was followed to remove the solvent. Sodium sulfate was used to remove any moisture in the tobacco oil. 5.00 ml of oil was obtained. As a comparative example, a rotary evaporator was used for solvent removal and the extraction solvents were methyl acetate and hexane.

Example 2 - Transesterification

3.028 g of tobacco oil were mixed with 10 ml of 1% H ₂ SO ₄ as catalyst, 10 ml of methanol, and 40 ml of a 5: 4 mixture of isopropanol (70%) / hexane. In one variation, CH ₃ OH / oil is 40: is mixed with 5% H ₂ SO ₄ to 1 molar ratio. A separatory funnel was used to separate the bottom layer with pH -7.5. The bottom layer was micro-filtered and then Na ₂ SO ₄ was added and sequestered from the resulting biodiesel product.

Example 3 - Characterization of product

The acid value of the biodiesel product was determined using a titrated oil sample mixed with 70% 2-propanol. A standardized titration procedure with 0.1 M KOH was used.

The biodiesel product was also tested for glycerol by iodine titration. Glycerol in biodiesel reduces periodate to iodate. The iodate or any remaining periodate is determined by reaction with the thiosulfate. The decrease in the amount of thiosulfate after the reaction was compared to the control, wherein the same initial amount of periodate was reacted with the thiosulfate. The result indicates the amount of glycerol present in the biodiesel. The total glycerol in the biodiesel of the present invention is less than 0.25 wt% of the biodiesel and the free glycerol is less than 0.02 wt% of the biodiesel.

It should be understood, however, that even though numerous features and advantages of the present invention have been set forth in the foregoing description, together with the details of construction and function of the present invention, the disclosure is only illustrative, It is to be understood that changes may be made in detail, particularly with regard to the shape, size and arrangement of parts, within the principles of the invention, to the full extent indicated by its broad general meaning.

Claims (18)

Extracting the oil from the tobacco biomass by a polar organic solvent selected from methyl acetate and ethyl acetate,
Removing the polar organic solvent,
Transesterifying the extracted oil, and
A method of producing biofuel from tobacco biomass comprising separating the biofuel from the products of the transesterification step. The method of claim 1, further comprising grinding the tobacco biomass prior to contacting the polar organic solvent. The method of claim 1, wherein the organic solvent is methyl acetate. The method of claim 1, wherein the amount of said polar organic solvent is about 1 to 4 grams per gram of biomass. The method of claim 1, wherein the extraction is performed over a period of from about 16 hours to about 48 hours. 2. The method of claim 1, wherein the extraction is enhanced by extraction enhancement techniques selected from the group consisting of sonication, heating, agitation, increased pressure, and / or exposure to radiation energy. The method of claim 1, wherein the polar organic solvent is removed by evaporation. 2. The process of claim 1 wherein the transesterification comprises contacting the oil with an alcohol in the presence of an acidic or basic catalyst. 9. The method of claim 8, wherein the alcohol is an alcohol containing up to four carbon atoms. 10. The method of claim 9, wherein said acid catalyst is a sulfonic acid, H ₂ SO _4, HC1, acetyl chloride, and is selected from the group consisting of BF _3. 10. The method of claim 9, wherein said basic catalyst is KOH, NaOH, NaOCH _3, Na ₂ CH ₂ CH _3, and is selected from the group consisting of guanidine. The method of claim 1, wherein the transesterification step is performed after the solvent removal step. The method of claim 1, wherein the tobacco biomass is obtained from hydroponically grown tobacco. 14. The method of claim 13, wherein the tobacco biomass is obtained from Navaho tobacco. 15. The method of claim 14, wherein the polar organic solvent is ethyl acetate. 16. The process of claim 15, wherein the transesterification step is performed using methanol and / or ethanol and a sulfuric acid catalyst. 17. The method of claim 16, further comprising separating methanol and / or ethanol from the biofuel. 18. The method of claim 17, further comprising washing the biofuel with water.