KR101116392B1 - Method of preparing bio fuels from algal galactans - Google Patents

Abstract

The present invention provides a petroleum substitute biofuel material such as 5-alkoxymethyl-2-furfural and levulinic acid alkyl ester in a single process without using a monoglycosylation reaction from galactane which can be extracted from giant seaweed. It relates to a manufacturing method.

According to the present invention, there is no problem affecting the grain price like the crop biomass resources by utilizing the giant seaweed which is a marine biomass resource, and the carbon source can be easily extracted as compared with the wood based biomass resources.

Macroalgae, galactan, catalytic conversion process, single process, petroleum substitute, biofuel, 5-alkoxymethyl-2-furfural, levulinic acid, alkyl esters

Description

METHOOD OF PREPARING BIO FUELS FROM ALGAL GALACTANS}

The present invention relates to a method for producing a biofuel using algal-derived galactan, and more particularly, a high energy density and hygroscopicity using a galactan which can be easily extracted from a large seaweed that can be utilized as marine biomass. A method for producing this low petroleum substitute biofuel.

Currently, about 35% of the total crude oil production is used as a raw material for many types of petrochemical products such as plastics, functional polymer materials, fibers, paints, adhesives, pharmaceuticals, and cosmetics. However, the price of petroleum resources is soaring due to limited reserves and increased demand due to the emergence of emerging developing countries such as China. As a result, many countries around the world are making great efforts to replace oil resources.

In particular, most of the aromatic compounds, which are the core raw materials of the omnidirectional chemical industry, are mostly obtained from petroleum. Recently, the most realistic alternative to the petroleum-based aromatic compounds is emerging as a biomass that can be recycled and used continuously. ) Is the utilization. Bioethanol is produced through saccharification and fermentation, starting with sugars such as sugar cane or starch-based materials such as corn, mainly from countries that already have a large cropland such as the United States and Brazil. It is industrially mass-produced and used as a fuel for transportation.

Biomass consists of crops used for food, such as sugar (sugar cane, sugar beets, etc.), starch (such as corn, potatoes, sweet potatoes, etc.), and wood (such as wood, rice straw, waste paper, etc.). Examples of the polysaccharide carbon source that can be obtained from biomass include starch or sugars that can be obtained from crop-based suppliers, and celluloses that can be obtained from wood-based suppliers. These polysaccharides are obtained through a pretreatment process from a biomass supplier. The polysaccharides of starch, sugar, and cellulose obtained through such pretreatment are converted to glucose or fructose, which is hexasaccharide, through a monosaccharide process by hydrolysis. It is then converted into ethanol and butanol as petroleum substitute fuels through a biofermentation process.

Specifically, a general preparation method for obtaining a desired final compound from a biomass source includes: (a) a pretreatment step for obtaining starch, sugar, cellulose, which is a polysaccharide material, (b) a monoglycosylation step for obtaining glucose, fructose, And (c) a multi-step process of biofermentation or catalytic chemical process to obtain the final compound is required, there is a problem that the yield is reduced in the course of this multi-step process.

In addition, because bioethanol produced from crop sources uses food resources, the sharing of arable land with food resources causes international grains to rise. Cultivation costs tend to be linked to oil prices, which has led to a lot of debate internationally.

In order to solve these problems, wood-based biomass that grows naturally in nature and uses wood that does not share crops and arable land, waste wood in the form of urban waste, or forest by-products scattered all over the forest can be used as raw materials. Interest in is increasing. However, in the case of such wood-based biomass, it is difficult to efficiently separate and remove the solid lignin, which occupies about 30% of the components in the pretreatment process, and much research on the utilization of waste lignin is required. Furthermore, cellulose, which is a starting material of woody biomass, is physically and chemically stable compared to sugar or starch, which is a starting material of crop biomass, and has a large difficulty in the conversion process.

In order to solve the above-mentioned problem, marine resources are attracting attention as the third generation biomass. Marine resources have a large available cultivation area, have little effect of cost increase due to the use of fresh water, land, fertilizer, etc. It is also very easy to pretreat because it does not contain difficult-to-remove ingredients such as lignin. Therefore, the development of conversion technology that can produce biofuel using marine biomass resources as a new source is expected to have important significance in the era of depetroleization.

Until now, research on marine biomass has mainly dealt with the extraction of triglycelide from microalgae and then conversion to fatty acid ester-based biodiesel through transition esterification. Due to difficulties in the process, it is showing the limitation of mass production as an alternative oil resource.

In terms of the use of biomass resources, currently industrialized bioethanol has a low energy content of about 75% of gasoline, so it is inevitable to change the existing engine for use as a single fuel, and because it is hygroscopic, it may corrode the engine or pipe. There is a great risk. In addition, when a biofermentation process is obtained from glucose, one-third of the carbon source on the mass balance is emitted as carbon dioxide, which is inherently inefficient.

For this reason, n-butanol is emerging as an alternative to ethanol. Although n-butanol has higher energy content and lower hygroscopicity than ethanol, fermentation process with new glucose is required, and research to develop it is currently underway.

Another alternative for solving the above problems is a bioether called second generation biodiesel. Bioethers have high energy content, and unlike alcohols, have no hydroxy group and thus have low hygroscopicity and low emissions.

Recently, Mascal et al. Succeeded in converting 5-chloromethylfurfural, a precursor of ethoxymethylfuran, from cellulose to a high yield of 75% or more, further increasing the possibility of mass production of ethoxymethylfuran from woody biomass. It was raised. However, during the etherification of 5-chloromethylfurfural, hydrochloric acid, which has a fatal effect on the engine, is produced as a by-product, making it an obstacle to mass production. [Mascal, M .; Nikinin, EB, Angew . Chem . Int . Ed . 2008 , 47 , 7924-7926]

The present invention provides a catalytic conversion process for easily producing biofuels that can be utilized as fossil fuel substitutes from renewable and sustainable biomass resources that are economically capable of mass cultivation, are rich in carbon sources, and are easy to extract. It aims to do it.

The present invention is to solve the above problems, the present invention can be supplied in large quantities at low cost, using galactan as a starting material that can be easily extracted as a major component of the seaweed, which is marine renewable resources, energy than gasoline The present invention relates to a method for producing alternative fuel or biofuel that can replace petroleum fuel with high density and low hygroscopicity. Moreover, unlike other biomass, the present invention is a new biomass capable of mass cultivation without affecting food resources and without problems such as resource destruction, and is used for producing petroleum substitute biofuel using seaweed, which is a marine supplier. Provide a method.

Specifically, the biofuel manufacturing method using the algae-derived galactan according to the present invention, the starting material manufacturing step (S10) for extracting galactan, a polysaccharide material from seaweed; By using the galactan, a reaction step of preparing a biofuel through a catalytic conversion reaction (S20) is included.

The biofuel desired in the present invention is preferably 5-alkoxymethyl-2-furfural represented by formula (I) and levulinic acid represented by formula (II), respectively. alkyl esters).

(I)

[Formula II]

Wherein, in Formulas (I) and (II), R ₁ and R ₂ are each one of an alkyl group, alkenyl, alkynyl, cycloalkyl, or aryl group.

5-alkoxymethyl-2-furfural of formula (I) is known as an ether derivative of 5-hydroxymethyl-2-furfural (HMF), and, as mentioned above, is a substance that is drawing attention as a next-generation fuel, and its energy density Is equal to or higher than conventional petroleum derived fuels such as gasoline or diesel, and significantly higher than bioethanol. Therefore, 5-methoxymethyl-2-furfural or 5-ethoxymethyl-2-furfural, which is typical of 5-alkoxymethyl-2-furfural, is a fossil fuel or MTBE (Methyl Tertiary Butyl Ether). It can be used as a substitute for fuel additives.

The levulinic acid alkyl esters of formula (II) may be used as fossil fuel alternative biofuels themselves, but may also be utilized as notable starting materials in the preparation of many useful 5-carbon compounds and derivatives thereof. For example, N-cyclohexyl-2-pyrrolidone prepared using this material is a solvent in many industrial applications, including electronics industry (photoresist stripping solutions), industrial cleaners, oil / gas well fats, and fiber dyeing. Or as an intermediate. N- [2-hydroxyethyl] -2-pyrrolidone is also useful in industrial cleaning, printing inks, and gasoline and oil additives. In addition, N-octyl-2-pyrrolidone is useful in industrial metal cleaners, printing inks and textile dyeing, for example, as detergents and dispersants in the manufacture of agricultural products.

Starting material manufacturing step (S10) is simply a step of extracting a polysaccharide material from seaweed, the present invention, by performing the reaction step (S20) using galactane among the polysaccharide material thus extracted, It is characterized by obtaining biofuels such as 5-alkoxymethyl-2-furfural and levulinic acid alkyl esters.

Here, the algae used in the present invention is preferably a giant algae, inhabits the sea such as red algae, brown algae, green algae, and may be used without limitation as long as it contains galactan. Examples of the red algae include wood starfish, laver, kotoney, dog gambling, round seaweed, ox radish, buckwheat, green grass fern, braids, jindubal, sesame gambling, spiny radish, silk grass, scabbard, stone star, stone tree, jinari Examples of brown algae include brown seaweed, kelp, halibut, minji, l, gorimae, brown seaweed, Ecklonia cava, gompi, rhubarb, sesame seaweed cousin, mabanban, hoe sang mabanban, jichungyi, 톳, and the like. In addition, the green algae may include cheontae, haecam, green, hearing, bead hearing, jade, saline and the like. From these seaweeds, polysaccharides such as cellulose and starch can be obtained in addition to galactan.

As a method for extracting galactan from the algae, any method used in the art may be used without limitation. For example, the seaweeds are immersed in an aqueous alkali solution for a certain time and washed with water, and the washed seaweeds are H ₂ SO ₄ , HCl, HBr, HNO ₃ , CH ₃ COOH, HCOOH, HClO ₄ (perchloric acid), H ₃ A method of extracting agar, carrageenan, and alginic acid may be used by immersion in an extraction solvent consisting of an acidic drug such as PO ₄ and PTSA (para-toluene sulfonic acid).

As galactan used by this invention, it is preferable to use agar. Agar as a representative galactan (Agar) is a natural polymer containing agarose (Agarose) as a monomer, agarose is a galactose (Galactose) and 3,6- anhydroglucose (1,3- It is a disaccharide substance consisting of anhydroglucose).

[Formula III]

In terms of chemical composition, the amount of agar in galactan obtained from a simple pretreatment from giant seaweeds is known to reach up to about 50-60% of the total components of some red algae such as Gelidium and Gracilaria. The remaining major constituents are about 10 to 20% of glucan, cellulose fiber, 10 to 20% of protein, and about 5 to 15% of lipid and ash, but they can be easily removed during extraction.

Unlike cellulose, which forms a crystalline form through intramolecular hydrogen bonding and has a very low solubility, the agar is an amorphous polymer material having excellent solubility in a polar solvent. Specifically, the agar is a hydrophilic organic material such as water or alcohol heated to about 80 ° C. Can be dissolved in a solvent. This solubility characteristic is an essential element for an efficient chemical conversion reaction and has a very important meaning. Furthermore, as in the reaction step (S20) of the present invention to be described later, when performing the conversion reaction by the acid catalyst, separation and purification is easy, there is no side reaction by the counter ion of the acid, recycling is possible, There is an advantage that can be used for heterogeneous solid acid catalyst that is easy to apply.

Reaction step (S20) according to an embodiment of the present invention is derived to establish the optimum conditions as such a conversion reaction, it is carried out by adding the galactane and a solid acid catalyst in a solvent, the metal catalyst conversion reaction.

That is, according to the reaction step (S20) according to an embodiment of the present invention, without the process of converting the polysaccharide galactane extracted through the starting material production step (S10) to monosaccharides by hydrolysis, the target in a single process Compounds 5-alkoxymethyl-2-furfural and levulinic acid alkyl esters can be obtained. In the following Reaction Scheme 1, as a preferred embodiment of the present invention, the process of obtaining the compound by a single reaction using agar as a galactan is briefly shown.

Scheme 1

Looking at the mechanism of the catalytic conversion reaction used in the present invention, first H ⁺ is bonded to the oxygen atom in the agar molecule is activated as a cation, then the electrons in the aga molecule move and the reaction begins. At this time, due to the movement of electrons, a situation in which chemical bonds in the molecule are simultaneously disconnected or regenerated occurs. As a result, many intermediates having an equilibrium relationship exist in the reaction solution. As the reaction time elapses, the equilibrium state is broken by the dehydration process, and the conversion to the substance having the most stable chemical structure is performed.The addition of etherification reaction and esterification reaction with alcohol, which is a preferable solvent, is further generated. Alkoxymethyl-2-furfural and levulinic acid alkyl esters are obtained as the final product.

Interestingly, unlike cellulose, agar reacts more sensitively under acidic conditions due to 3,6-anhydroglucose with a higher ring strain in its chemical structure, and the link between agarose is not a typical C1-C4 link. -C3 is expected to be different chemical structure of intermediates, such as glucose, which is a starting material derived from existing crop and wood biomass resources, such as acid catalyst strength, concentration, reaction solution concentration, solvent type, temperature, time, etc. New reaction conditions are required which are completely different from fructose and cellulose.

Here, the (heterogeneous) solid acid catalyst used in the embodiment of the present invention is a variety of ion exchange resins, zeolites, metal silicates, acid resins, natural clay minerals, silica saturated inorganic acid ( silica impregnated with mineral acid), heat treated charcoal, metal oxides, metal sulfides, metal salts, mixed oxides, or mixtures thereof may be used without particular limitation.

In addition, it is preferable to use an alcohol solvent as said solvent. As the alcoholic solvent used in the present invention, as the primary aliphatic alcohol, preferably methanol, ethanol, propanol, 2-hydroxymethyl-propanol, butanol and the like can be used.

Here, a preferable ratio of the solvent and galactane added thereto is 0.5 to 50 g / L, more preferably 1 to 20 g / L (wt / V), and shows excellent yield when applied in the above ratio. It was. In addition, the concentration of the solid acid catalyst to maximize the yield is 0.05 to 1.0M, more preferably 0.1 to 0.5M. Furthermore, the preferred reaction temperature of the reaction step (S20) according to one embodiment of the present invention is 50 to 200 ℃, more preferably 70 to 150 ℃, the reaction time is 1 to 20 hours. In general, the reaction is not performed well if the temperature is less than 50 ℃, there is a problem in that the yield is reduced because a lot of by-products such as humin (humin) is generated when the temperature is higher than 200 ℃.

As described above, according to the biofuel production method using seaweed-derived galactan according to the present invention, biofuel can be easily produced in a single step.

As described above, according to the present invention, there is no problem affecting the grain prices like the crop biomass resources by utilizing the giant seaweeds, which are marine biomass resources, and the carbon source can be extracted more easily than the wood based biomass resources. .

In addition, according to the present invention, there is an effect that can replace bioethanol having a lower energy density than conventional petroleum fuel.

Hereinafter, the biofuel production method using the algae-derived galactan according to the present invention will be described.

Example 1 (5-ethoxymethyl-2-furfural, levulinic acid ethyl ester production)

Into a 250 mL round-bottom flask, add 1 g of agar, 1 g of Dowex ion exchange resin as a solid acid catalyst, 20 mL of n-ethanol as a solvent and reagent, stir to form a suspension, and install a reflux condenser. After heating to ℃ ℃ stirred at 240 rpm to proceed the reaction for 18 hours. At this time, the color of the reaction solution turned from colorless to brown (about 4 to 5 hours after the start of the reaction). The reaction solution was separated and HPLC (FIG. 1) and GC-Mass analysis confirmed that 5-ethoxymethyl-2-furfural and levulinic acid ethyl ester were produced in a ratio of 3: 1 (selectivity> 90%). ). After the reaction, the solid acid catalyst in the reaction mixture and the side reaction solid material, humin, were removed by a filter, and the solvent of the remaining solution was removed under reduced pressure. The resulting mixture was subjected to column chromatography (hexane: ethyl acetate = 10: 1 → 5 The mixture was separated through: 1) to obtain a mixture of 5-ethoxymethyl-2-furfural and levulinic acid ethyl ester in a yield of 10% (100 mg), and confirmed by NMR (FIG. 2).

1 is a diagram showing the HPLC of the material generated from agar through the solid acid catalytic conversion process in the ethanol solvent, each peak represents 5-ethoxymethyl-2-furfural and levulinic acid ethyl ester .

In addition, Figure 2 is a diagram showing the ¹ H-NMR of the mixture of 5-ethoxymethyl-2-furfural and levulinic acid ethyl ester obtained after separation and purification of the material produced from the agar through column chromatography The positions of protons corresponding to the numbers are indicated by numbers.

Example 2 (5-butoxymethyl-2-furfural, levulinic acid butyl ester production, 5% agar solution)

Into a 250 mL round-bottom flask, add 1 g of agar, 1 g of Dowex ion exchange resin as a solid acid catalyst, 20 mL of n-butanol as a solvent and reagent, stir to form a suspension, and install a reflux condenser. After heating to ℃, the reaction proceeds for 30 hours while stirring at 240 rpm. At this time, the color of the reaction solution turned from colorless to brown (about 4 to 5 hours after the start of the reaction). After the reaction, the solid acid catalyst in the reaction mixture and the side reaction solid material, humin, were removed by a filter, and the solvent of the remaining solution was removed under reduced pressure. The resulting mixture was subjected to column chromatography (hexane: ethyl acetate = 10: 1 → 5 1) to obtain a mixture of 5-butoxymethyl-2-furfural and levulinic acid butyl ester in a yield of about 20% (200 mg).

Example 3 (5-butoxymethyl-2-furfural, levulinic acid butyl ester production, 20% agar solution)

Into a 250 mL round-bottom flask, add 4 g of agar, 4 g of Dowex ion exchange resin as a solid acid catalyst, 20 mL of n-butanol as a solvent and reagent, stir to form a suspension, and install a reflux condenser. After heating to ℃, the reaction proceeds for 30 hours while stirring at 240 rpm. At this time, the color of the reaction solution turned from colorless to brown (about 4 to 5 hours after the start of the reaction). After the reaction, the solid acid catalyst in the reaction mixture and the side reaction solid material, humin, were removed by a filter, and the solvent of the remaining solution was removed under reduced pressure. The resulting mixture was subjected to column chromatography (hexane: ethyl acetate = 10: 1 → 5 It was separated through 1) to obtain a mixture of 5-butoxymethyl-2-furfural and levulinic acid butyl ester in a yield of about 20% (800 mg) and confirmed through NMR (Fig. 3).

3 is a mixture of 5-butoxymethyl-2-furfural and levulinic acid butyl ester mixture obtained by separating and purifying a substance produced from agar through a solid acid catalytic conversion process in the ethanol solvent through column chromatography. ¹ H-NMR is a diagram showing the position of the proton corresponding to each material by numbers.

In the above, the embodiment of the present invention has been described in detail. However, the scope of the present invention is not limited to the above embodiments, but includes a range that can be easily converted or deleted within the scope of the appended claims, and without departing from the gist of the invention claimed in the claims. Anyone skilled in the art is deemed to fall within the scope of the claims described herein to the extent possible to vary.

1 is a diagram showing the HPLC of the product according to Example 1 of the present invention, each peak represents 5-ethoxymethyl-2-furfural and levulinic acid ethyl ester.

FIG. 2 is a diagram showing ¹ H-NMR of a mixture of 5-ethoxymethyl-2-furfural and levulinic acid ethyl ester obtained after separating and purifying a product according to Example 1 through column chromatography. , The positions of protons corresponding to the respective substances are indicated by numbers.

3 is a diagram showing ¹ H-NMR of a mixture of 5-butoxymethyl-2-furfural and levulinic acid butyl ester obtained after separation and purification of a product according to Example 3 of the present invention by column chromatography. The positions of protons corresponding to each material are indicated by numbers.

Claims (10)

A starting material manufacturing step of extracting galactan, a polysaccharide material from seaweed; Adding a solid acid catalyst and the galactane in an alcohol solvent to perform a catalytic conversion reaction to produce a biofuel, wherein the biofuel is 5-alkoxymethyl-2-fur represented by the following Chemical Formula I: A method for producing a biofuel using algal-derived galactane, which is a fural and levulinic acid alkyl ester represented by the formula (II). (I)

[Formula II]

In formula (I) and formula (II), R ₁ and R ₂ are each one of an alkyl group, alkenyl, alkynyl, cycloalkyl, or aryl group. delete The method of claim 1, The seaweed is a method of producing a biofuel using algal-derived galactan, characterized in that the giant seaweed. The method of claim 1, The galactan is agar (agar), characterized in that the biofuel production method using the algae-derived galactan. delete delete The method of claim 1, The ratio of the said alcohol solvent and said galactan is 0.5-50 g / L, The manufacturing method of the biofuel using seaweed derived galactan characterized by the above-mentioned. The method of claim 1, The acid concentration of the solid acid catalyst is a method for producing a biofuel using seaweed-derived galactane, characterized in that 0.05 to 1.0M. The method of claim 1, The reaction temperature of the reaction step, the biofuel production method using seaweed-derived galactane, characterized in that 50 to 200 ℃. The method of claim 1, The reaction time of the reaction step is a method for producing a biofuel using seaweed-derived galactane, characterized in that 3 to 50 hours.

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