JP2009138185A - Method for producing biofuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method, by which an ester useful as a biofuel can be produced from fat and oil through an extremely short-time reaction at a high conversion rate even with a small amount of an enzyme, for producing a biofuel. <P>SOLUTION: In the method for producing a biofuel, wherein esterification occurs when waste clay dispersed in an organic solvent is reacted with a lower monohydric alcohol in the presence of the enzyme, the reaction is performed in the co-presence of zeolite, sodium carbonate or alumina. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing biofuel, and more particularly to a method for producing biofuel using fats and oils in waste clay.

  Environmentally friendly fuels using fats and oils are known as biofuels. In this biofuel, caustic soda and methanol are allowed to act on used tempura oil to obtain methyl ester used as biofuel.

  In the above method, esterification is generally carried out by an alkali catalyst method or an acid catalyst method, but this method has many steps, and the alkali, acid and by-product glycerin and soap used in the reaction system are used in the reaction system. Since it remains, there exists a problem that the complicated operation for removing this is needed.

  As a method for avoiding the above disadvantages, there is known a method of producing a methyl ester used as a biofuel by reacting fats and oils with methanol using an enzyme such as lipase as a catalyst. For example, Patent Documents 1 and 2 propose a method of reacting fats and oils with methanol in the presence of an enzyme and zeolite. Moreover, the method of making fats and oils react with methanol in presence of an enzyme and alkaline substances (sodium carbonate etc.) is also proposed (patent document 3). Furthermore, the applicant of the present invention firstly converted a fat and oil supported on the waste white clay into methyl ester by allowing an enzyme such as lipase to act on the waste white clay as a by-product in the field of fat and oil purification. Proposed (Patent Document 4).

As described in Patent Documents 1 to 4, the method using an enzyme as a catalyst separates a fatty acid because the fatty acid is converted to a methyl ester even when free fatty acid is contained in the fat and oil. There is an advantage that there is no need and a step of removing acid or alkali from the reaction system is unnecessary.
JP 59-28482 A Japanese Patent Laid-Open No. 2-203790 JP-A-2-203789 JP 2003-336082 A

  By the way, the method proposed by the said patent document 1 suppresses hydrolysis of the produced | generated methyl ester by using a zeolite as a dehydrating agent, Thereby, methyl ester can be obtained with high conversion. In Patent Documents 2 and 3, there is an effect of prolonging the life of the enzyme by adding a porous material (zeolite or the like) or an alkaline material (sodium carbonate or the like). A large amount of waste clay produced as a by-product in the refining process and originally discarded is used as an oil and fat source, and has the advantage of being industrially useful from the viewpoint of resource reuse.

  However, in the method using an enzyme as a catalyst as shown in the above prior art, a large amount of expensive enzyme must be used in order to obtain a methyl ester at a high conversion rate, and the production cost is extremely high. There is a big problem of becoming. For example, if the amount of enzyme is reduced in order to reduce the production cost, if an attempt is made to produce a methyl ester at a conversion rate of 80% or more, the reaction must be carried out for a very long time, resulting in a lower raw material cost. Only the total manufacturing cost is not reduced.

  Therefore, an object of the present invention is to provide a method for producing a biofuel containing no free alkali, which can produce an ester useful as a biofuel from fats and oils at a high conversion rate by a reaction in a very short time even with a small amount of enzyme. It is to provide.

  As a result of intensive studies on a method for converting fats and oils into biofuels using enzymes as catalysts, the present inventors have found that when waste clay is used as a fat and oil source, a specific inorganic compound accelerates the esterification reaction. In the state where such a reaction accelerator coexists with waste clay, enzyme and lower monohydric alcohol, the fats and oils in the waste clay are converted into biofuel (esterified product of lower monohydric alcohol). In some cases, even when the amount of the enzyme is remarkably reduced, an unexpected finding that a biofuel can be obtained at a high conversion rate of 80% or more in a short time has been found, and the present invention has been completed.

That is, according to the present invention, in the method for producing a biofuel, the waste white clay dispersed in an organic solvent is reacted with a lower monohydric alcohol in the presence of an enzyme to form an ester.
There is provided a method for producing a biofuel, characterized in that the reaction is carried out in the presence of at least one reaction accelerator selected from the group consisting of an alkaline inorganic compound and aluminum oxide or hydroxide.

In the production method of the present invention,
(1) per 100 parts by weight of the waste clay, adding 0.01 to 1.0 part by weight of enzyme and 0.1 to 10 parts by weight of the reaction accelerator in the organic solvent;
(2) The use of a metal-containing alkaline inorganic compound of Group 1 and / or Group 2 of the periodic table as the alkaline inorganic compound;
(3) using zeolite or sodium carbonate as the alkaline inorganic compound;
(4) Use of zeolite A as the zeolite,
(5) Use of the zeolite having an ignition loss at 860 ° C. of 15% by weight or more,
(6) As said aluminum oxide thru | or hydroxide, BET specific surface area is 100 m < ² > / g.
Using the above aluminum oxide or hydroxide,
(7) performing the reaction at 20 to 50 ° C.,
(8) using lipase as an enzyme,
(9) using methanol as the lower monohydric alcohol,
(10) The organic solvent, waste clay, enzyme, lower monohydric alcohol and reaction accelerator are put into a reaction vessel and mixed with stirring to react the fat and oil in the waste clay with the lower monohydric alcohol. To produce an ester,
Is preferred.

  In the present invention, waste white clay dispersed in an organic solvent is reacted with a lower monohydric alcohol in the presence of an enzyme to produce an ester. In this reaction, an alkaline inorganic compound (eg, zeolite) and aluminum oxide are produced. It is an important feature that at least one selected from the group consisting of hydroxides is allowed to coexist as a reaction accelerator, so that even when the amount of enzyme is significantly reduced, 80% or more can be achieved in a very short time. Esters that become biofuels can be produced at a high conversion rate, and production costs can be greatly reduced. For example, as shown in the experimental results of Examples to be described later, the reaction time of only 72 hours is obtained by using only 0.1 parts by weight of enzyme (lipase) with respect to 100 parts by weight of waste clay. The methyl ester can be obtained from the fats and oils in the waste clay with a conversion rate of% (see Example 1).

  In the present invention, the reason why the amount of enzyme can be remarkably reduced by coexistence of an alkaline inorganic compound such as zeolite or aluminum oxide or hydroxide has not been clarified yet. Is estimated as follows.

  That is, fats and oils are fatty acid triglycerides, and a lower monohydric alcohol ester of a fatty acid is produced by transesterification (specifically, alcoholysis) by allowing a lower monohydric alcohol such as methanol to act in the presence of an enzyme. Alternatively, fats and oils are once hydrolyzed to produce fatty acids, and these fatty acids are dehydrated and condensed with lower monohydric alcohols to produce esters. Enzymes have a catalytic action for the above-mentioned reactions such as transesterification or hydrolysis and esterification of fats and oils.

By the way, as described in Patent Documents 1 and 2, it is known that a methyl ester is produced from fats and oils in the presence of zeolite and an enzyme. In this case, the zeolite acts as a dehydrating agent and suppresses hydrolysis of the produced methyl ester, whereby the methyl ester can be obtained at a high conversion rate. However, as shown in Comparative Example 5 to be described later, when the fat / oil itself is reacted with methanol in the presence of zeolite and an enzyme, an enzyme (lipase) amount of 0.3% by weight per fat / oil is only 1. The methyl ester can only be obtained with a conversion of 2%. On the other hand, when using white clay (oil content: 30% by weight) as the oil source and reacting with methanol in the presence of zeolite and enzyme, 0.3% by weight per oil content is obtained. A methyl ester is obtained with a conversion rate of 80% or more in terms of the amount of enzyme (lipase) (Example 3).
This is the same even when sodium carbonate or aluminum oxide or hydroxide is used. When these oils and fats are coexisted in a system in which they are reacted with methanol in the presence of an enzyme, the conversion rate to methyl ester. Is extremely low (see Comparative Example 7 and Comparative Example 8), however, when waste clay is coexisted in the system using the oil and fat source, the conversion rate to methyl ester is remarkably improved (Example 4). See Example 8).

  As understood from the above experimental results, in the present invention, the reaction accelerator selected from alkaline inorganic compounds represented by zeolite and aluminum oxide or hydroxide does not function as a dehydrating agent. The waste clay supporting the fat and oil, together with the reaction accelerator, as a catalyst directly or as an enzyme co-catalyst for transesterification and hydrolysis of the fat and oil and esterification of the fatty acid produced by hydrolysis, or It has a function of suppressing the inhibitory factor of the enzyme, and it is presumed that the conversion reaction from fats and oils to lower monohydric alcohol esters of fatty acids is significantly accelerated by these synergistic effects.

  In addition, the fact that the reaction accelerator used in the present invention does not improve the conversion rate due to the dehydration function means that methyl ester is also used when a zeolite having almost no dehydration function is used as the reaction accelerator. It is understood from the fact that the conversion rate to That is, the zeolite exhibiting a dehydrating function has been subjected to a heat treatment at a high temperature such as calcination, and adsorbed moisture, crystal water and the like have been removed by the heat treatment, so the loss on ignition is remarkably small, for example, 860 ° C. The loss on ignition is 10% by weight or less. However, in the present invention, the heat treatment as described above is not performed, and the conversion rate to monohydric alcohol ester is remarkably improved even when the ignition loss (860 ° C.) is 15 wt% or more. It can be done. For example, the zeolite used in Example 1 described later is not calcined, and its loss on ignition (860 ° C.) is 22.3% by weight.

  As described above, the biofuel production method of the present invention originally uses waste white clay to be discarded as an oil and fat source, and remarkably reduces the amount of expensive enzymes used in a short time and with a high conversion rate. Since a monohydric alcohol ester can be produced, it is extremely useful industrially from the viewpoint of resource saving, production cost, and the like.

  In outline, the production method of the present invention is made by allowing a lower monohydric alcohol to act on the oil and fat in the waste clay in the presence of an enzyme and a reaction accelerator, thereby converting the oil and fat into a lower monohydric alcohol ester of fatty acid, that is, biofuel. It is something to change.

<Waste white earth>
The waste clay used in the method of the present invention uses bleached soil for decolorization or purification of fats and oils, and is separated and by-produced in this step, and contains oil, and discarding it is a point of environmental pollution. It was not permitted by the company, and its effective use was eagerly desired. Clay containing montmorillonite as the main component, such as Ca-type bentonite and acid clay, activated clay obtained by acid treatment and / or alkali treatment of this clay, and attapulgite are called bleaching clay.

  That is, bleaching earth is added to the fat to be decolored or refined as a decoloring agent or purifying agent in the form of a powder, and both are uniformly stirred, whereby the coloring components and impurities contained in the fat are added to the bleaching earth particles. Adsorb. In the waste white clay separated after decoloring or refining treatment, an amount of oil and fat corresponding to the oil absorption of the used bleaching earth is retained.

  The bleaching or refining treatment of fats and oils is a per se known condition. For example, 0.1 to 5% of bleaching earth is added as a decoloring or purifying agent based on the weight per fat and oil, and a temperature of 90 to 150 ° C. The decolorization or purification treatment can be completed by stirring both compositions for a minute.

  The mixture after decoloring or refining treatment is supplied to any filter, such as a filter press, belt filter, oliver filter, American filter, centrifugal filter, etc. So-called waste clay, which is a used decolorizing or purifying agent, is obtained. Depending on the type of raw material oil to be refined, the waste white clay generally contains about 20 to 60% by weight of oil and fat retained in the particles. In addition, the fats and oils contain about 1 to 40% by weight of free fatty acids together with glycerides in 100% by weight of the fats and oils. In the present invention, the fats and oils are converted into lower monohydric alcohol esters using enzymes as catalysts. Therefore, the free fatty acid is also esterified at the same time, and therefore a process such as removal of such free fatty acid is unnecessary.

  That is, for decolorization and refining of fats and oils, clays such as Ca-type bentonite and attapulgite or acid-treated products of these clays are used as bleaching soil for decoloring or purification, and montmorillonite such as Ca-type bentonite and acid clay is mainly used. In particular, clay and acid-treated products thereof are frequently used. The waste clay used as the oil source in the present invention is a used substance.

  Montmorillonite, which is a main component of acid clay, etc., has a basic unit of a three-layer structure in which two SiO4 tetrahedral layers are sandwiched between AlO6 octahedral layers. It is an aluminosilicate that is laminated in the axial direction to form a layered crystal structure. This layered crystal structure is common to smectite group clay minerals containing montmorillonite.

  Among the clays mainly composed of montmorillonite, acidic white clay widely produced in Japan is weathered, and some Al atoms in the AlO6 octahedron layer in the three-layer structure, which is the basic unit of montmorillonite, are replaced with magnesium or iron. The hydrogen ions are bonded to compensate for the valence. Therefore, when acidic clay is suspended in a saline solution and the pH thereof is measured, the hydrogen ions are replaced with sodium (Na) ions to show acidity. On the other hand, bentonite is mostly sodium (Na) as an exchangeable cation, so pH is neutral to slightly alkaline and water swellability is large, whereas in acidic clay, sodium ions are alkaline earth metals. Since it is substituted, the alkali metal component is small, the water swellability is reduced, and the silicic acid content is high, which is very advantageous in terms of adsorptivity. Thus, as the clay mainly composed of montmorillonite, any acidic white clay produced in Japan is widely used, and clay called Ca-type bentonite is used worldwide.

Below, an example of the general chemical composition of the acid clay (100 degreeC dry goods) used for the decoloring thru | or refinement | purification of fats and oils is shown.
Chemical composition of acid clay:
SiO _2: 61.0~74.0 (% by weight)
Al ₂ O ₃ : 12.0 to 23.0
Fe ₂ O _3: 2.0~3.5
MgO: 3.0-7.0
CaO: 1.0-4.0
K ₂ O: 0.3~2.0
Na ₂ O: 0.3~2.0
Ig. loss: 5.0-10.0

  When acid clay is used, cristobalite, quartz, feldspar and the like contained in the rock can be easily separated by a separation method using a difference in specific gravity (classification means such as water tank or wind tank). Among them, the crystalline silicic acid cristobalite can easily be reacted with an alkali and converted into an alkali silicate, so that it can also be removed by this method. By these methods, the purity of the layered crystal structure can be improved.

On the other hand, acid-treated products of acidic clay are generally known as activated clay which is a refining agent such as fats and oils. This acid-treated product is easily prepared by treating acidic clay with a mineral acid solution such as sulfuric acid or hydrochloric acid, eluting a part of the basic components contained therein, and washing. This acid treatment destroys part of the layered crystal structure originally possessed by the acid clay, but increases the content of silicic acid (SiO ₂ ), which increases the specific surface area, adsorbing capacity, etc. The physical properties are improved. The acid-treated product of acid clay, generally activated clay commercially available, and the intermediate product thereof become a refining agent having excellent characteristics.

The chemical composition of the acid-treated product differs depending on the type of raw acid clay and acid treatment conditions, but generally has the composition shown below.
Chemical composition of activated clay (acid-treated acid clay);
SiO _2: 65.0~83.0 (% by weight)
Al ₂ O _3: 5.0~12.0
Fe ₂ O _3: 1.0~3.5
MgO: 1.0-7.0
CaO: 0.5-4.0
K ₂ O: 0.2~2.0
Na ₂ O: 0.2~2.0
Ig. loss: 5.0-10.0

  After the acid clay or activated clay as described above is used for decoloring or refining of fats and oils, the recovered waste clay is loaded with fats and oils. In the present invention, such waste clays, strictly speaking, The fat and oil supported on the bleaching earth is used as the fat and oil source. Such fats and oils are mainly composed of esters of fatty acid and glycerin, such as safflower oil, soybean oil, rapeseed oil, palm oil, palm kernel oil, cottonseed oil, coconut oil, rice bran oil, sesame oil, castor Examples thereof include vegetable oils such as oil, linseed oil, olive oil, tung oil, cocoon oil, peanut oil, kapok oil, cacao oil, wood wax, sunflower oil and corn oil, and animal oils such as beef tallow, whale oil and fish oil.

  The above fats and oils are generally contained in the waste clay in an amount of about 20 to 60% by weight. This includes free fatty acids in an amount of about 1 to 40% by weight in 100% by weight of fats and oils.

<Enzyme>
In the present invention, any enzyme can be used as long as it can produce an ester (biofuel) of a lower monohydric alcohol by transesterification or hydrolysis and hydrolysis of a fatty acid produced by hydrolysis. In general, lipase is used. The origin of the lipase is not particularly limited, and lipases derived from microorganisms, lipases derived from plants, lipases derived from animal pancreas, and the like are used. The lipase to be used may be immobilized on an appropriate carrier.

  Specific examples of lipases include lipase QLM derived from Alcaligenes sp (named sugar industry), lipase OF derived from Candida cylindracea (named sugar industry), lipase Type VII (sigma) derived from Candida rugosa, lipase type 11 derived from Rhizopus arrhizus (Sigma) ), Rhizopus oryzae-derived lipase F-AP15 (Amano Enzyme), Rhizopus japonicus NR400-derived lipase A-10FG (Nagase), Aspergillus niger-derived SumizymeNLS (Nippon Kagaku), Phycomyces nitens NRRL 2444-derived lipase PN (Wako) Porcine pancreas-derived lipase Type II (Sigma), Pseudomonas cepacia-derived lipase (Sigma), Mucor javanicus-derived lipase (Sigma), alkaline lipase (NOVO), and the like. Yes, it is not limited to this in any way.

<Reaction accelerator>
In the present invention, together with the enzymes described above, at least one of an alkaline inorganic compound and aluminum oxide or hydroxide is used as a reaction accelerator. Other than these, for example, ion exchange resins and acidic to neutral inorganic compounds have no function as a reaction accelerator. The reaction accelerator is added in an amount of 0.1 to 10 parts by weight, preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight per 100 parts by weight of the waste clay.

  As the above alkaline inorganic compound, that is, an inorganic compound exhibiting alkalinity when dissolved or dispersed in water, an alkaline inorganic compound containing a metal of Group 1 and / or Group 2 of the periodic table is preferable. That is, by carrying out a reaction using an enzyme as a catalyst in the presence of such an alkaline inorganic compound, the reaction is remarkably accelerated even with a small amount of enzyme, and a lower monohydric alcohol ester that becomes a biofuel in a short time and at a high conversion rate is obtained. It is obtained.

  In the present invention, examples of the alkaline inorganic compound containing an alkaline metal as described above are those having a pH (25 ° C.) of 8.5 or more when measured with an aqueous solution or aqueous dispersion at a concentration of 5% by weight, for example. Specifically, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate, alkaline earth metal compounds such as calcium hydroxide, barium hydroxide, calcium carbonate and barium carbonate, hydroxide Examples include magnesium, magnesium carbonate, composite oxides of silica and magnesia, and zeolites such as A-type, Y-type, X-type, mordenite, clinoptilolite containing Group 1 and / or 2 metals. it can. Particularly effective in the present invention are A-type zeolite, Y-type zeolite and sodium carbonate. In this case, NaHCO3 is an alkaline inorganic compound having a pH lower than the above, but the effect of contributing to the promotion of the reaction is small.

  Further, as described above, a zeolite that has not been subjected to a heat treatment such as calcination and has an ignition loss (860 ° C.) of 15% by weight or more, particularly 20% by weight or more is suitable. That is, since the zeolite used in the present invention does not promote the reaction by the dehydration function, it is possible to use a zeolite with a large loss on ignition, and such a zeolite has a degree of drying even if heat treatment is performed. Therefore, there is an advantage that the production cost is low. A further advantage of zeolite is that the Na content of the zeolite does not elute into the biofuel. When biofuel containing Na is used for the engine, metal corrosion of the device occurs. However, even when zeolite is used as a reaction accelerator in the present invention, Na content is hardly eluted (see Example 1).

In the present invention, aluminum oxide or hydroxide can also be used as a reaction accelerator, and even when aluminum oxide or hydroxide is used, a high conversion rate to methyl ester can be obtained. it can. Examples of such aluminum oxides or hydroxides include amorphous aluminum hydroxide; crystalline water such as boehmite, pseudoboehmite, diaspore, gibbsite and bayerite obtained by heating and baking amorphous aluminum hydroxide. Aluminum oxide; γ-alumina, η-alumina, χ-alumina, α-alumina, etc. produced during the dehydration process of alumina hydrate. Particularly preferred are boehmite, pseudoboehmite and γ-alumina. An aluminum oxide or hydroxide having a larger specific surface area is more effective. For example, an aluminum oxide or hydroxide having a BET specific surface area of 100 m ² / g or more, particularly 180 to 400 m ² / g. Most preferred. When the specific surface area is smaller than 100 m 2 / g, the effect of contributing to the promotion of the reaction is slightly low.

<Lower monohydric alcohol>
Examples of lower monohydric alcohols used for esterification include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, pentanol, 3-methyl-1-butanol, hexanol, heptanol, octanol and the like The alcohol having 8 or less carbon atoms may be mentioned, but 7 or less carbon atoms are particularly preferable, and methanol is particularly preferable in terms of reactivity and cost.

<Reaction>
In the present invention, the esterification reaction in which the lower monohydric alcohol is allowed to act on the oil and fat in the waste clay in the presence of the enzyme and reaction accelerator described above is an organic solvent, waste clay, enzyme, lower monohydric alcohol, and reaction accelerator. Is stirred and mixed in a temperature range in which the enzyme is not deactivated, for example, 20 to 50 ° C., particularly 20 to 40 ° C. That is, as a reaction form, for example, a method in which an enzyme or a reaction accelerator is packed in a column and waste clay or lower monohydric alcohol is continuously supplied to this column can be adopted. Therefore, the batch method as described above is most suitable.

  The organic solvent is not particularly limited as long as it does not inhibit the above reaction and can dissolve the lower monohydric alcohol to be used for the reaction, the fat and oil in the waste clay, and the ester to be formed, but in general, hexane, Uses aliphatic hydrocarbon solvents such as heptane and petroleum ether, aromatic hydrocarbon solvents such as benzene, toluene and xylene, ether solvents such as dimethyl ether and diethyl ether, ketone solvents such as acetone, light oil and kerosene Is done.

  The amount of the organic solvent is sufficient for the waste clay to be fluidized, but is not limited thereto.

  The amount of enzyme used is set according to the amount of fats and oils contained in the waste clay, but in the present invention, the reaction is accelerated particularly by the combined use of a reaction accelerator, so the cost and the desired conversion rate, The amount of enzyme used should be determined in consideration of the reaction time for obtaining the conversion rate. The upper limit of the amount of the enzyme used is not particularly limited, but the enzyme is very expensive, and the use of a large amount of enzyme results in a significant increase in production cost. Therefore, in general, the amount of enzyme used should be 0.01 to 1.0 part by weight per 100 parts by weight of waste clay.

  Further, the amount of the reaction accelerator used is slightly different depending on the amount of oil and fat contained in the waste clay, but is generally in the range of 0.1 to 10 parts by weight per 100 parts by weight of the waste clay. That is, when a reaction accelerator is used in a larger amount than the above range, a further increase in the reaction promotion effect cannot be expected, and only an increase in cost is brought about. When the amount is less than the above range, a sufficient reaction promoting effect cannot be obtained, and when the amount of the enzyme is reduced, the reaction time until a desired conversion rate is achieved becomes long.

  The lower monohydric alcohol is preferably used in an amount equal to or greater than the equivalent amount of fatty acids (including free fatty acids) generated from the fats and oils carried on the waste clay, and particularly the fatty acid: alcohol (molar ratio) is from 1: 3 to The amount is 1: 6, preferably 1: 3.5 to 1: 5. If the amount of alcohol is higher than this, the enzyme is deactivated.

  The order of addition of each component is arbitrary. For example, a lower monohydric alcohol and waste clay are mixed, an organic solvent is added to the mixture to uniformly disperse the waste clay, and then enzyme powder and reaction accelerator are added. Alternatively, after the waste clay is first dispersed in the organic solvent, the lower monohydric alcohol, the enzyme and the reaction accelerator can be added all at once. In addition, the lower monohydric alcohol, the enzyme, the reaction accelerator, and the like can be added in the form of an aqueous solution depending on the type, but in general, it is desirable to avoid introducing excessive water into the reaction system. . This is because the introduction of excessive moisture causes the produced ester to hydrolyze and tends to lower the ester conversion rate.

  The ester of the fatty acid produced by the reaction as described above can be separated and recovered by a purification means known per se such as centrifugation, distillation, extraction and the like. In addition, in this invention using waste white clay as a fats and oils source, since the glycerol byproduced is adsorbed by waste white clay, there also exists an advantage that the isolation | separation process of glycerol can be skipped.

  In addition, unreacted glycerides or enzymes may remain in the waste clay residue after the ester is separated. It is also possible to extract the glyceride contained in this residue and recycle it in the reaction step described above. Moreover, the enzyme contained in a waste white clay residue can also be reused as needed.

  In the present invention described above, an ester of a lower monohydric alcohol can be obtained with a high conversion rate by a reaction in a short time even with a small amount of enzyme, and the production cost is greatly reduced, which is extremely useful industrially.

  A silica / magnesia preparation, which is a powder of a composite oxide of silica and magnesia, may also be used for decolorization and purification of fats and oils (see, for example, JP-A-2005-8676). Utilizing the above-described present invention, the used waste silica / magnesia preparation discharged from the food service industry or the like as an oil / fat source, and reacting with a lower monohydric alcohol such as methanol in the presence of an enzyme to become a fuel Can be manufactured. In addition, it is also possible to produce an ester serving as a fuel by reacting a lower monohydric alcohol such as methanol in the presence of an enzyme, using spent waste clay mixed with waste silica / magnesia preparation as an oil and fat source. In this case, since the magnesia component in the silica / magnesia preparation has a function as a reaction accelerator (alkaline inorganic compound) in the present invention, a high conversion rate should be ensured without adding a reaction accelerator separately. Can do.

  The excellent effects of the present invention will be described with reference to the following examples and comparative examples. The measurement was performed by the following method.

(1) Method for measuring fat and oil content in waste white soil Established by the Japan Oil Chemists' Society Standard oil and fat analysis method In accordance with 1.5-1996, oil and fat content in waste white clay is obtained using n-hexane as an organic solvent reagent. It was.

(2) Method for measuring methyl ester concentration The reaction solution was filtered through a membrane filter after centrifugation, and 500 mg was mixed with 5 g of light oil to obtain a sample solution.
This is a high-speed pump composed of a liquid pump LC-20AD, an autosampler SIL-20A, a column oven CTO-20A, a differential refractive index detector RID-10A and a controller CM-20A (each made by Shimadzu Corporation) and a data processing device. Measurement was performed under the following conditions using a liquid chromatograph system to obtain a methyl ester peak area of the sample.
Column: Luna 5u Silica (2) 100A
(Phenomenex made)
Column temperature: 40 ° C
Eluent: 0.4 vol% 2-propanol and 99.4 vol% n-hexane mixture eluent Flow rate: 1.0 ml / min Injection volume: 10 μl
For the calibration curve, stearic acid standard products (manufactured by Wako Pure Chemical Industries, Ltd.) were measured in the same manner using a mixed solution of 10 mg, 50 mg, 100 mg, 500 mg and 5 g of light oil as standard solutions, and a calibration curve of methyl ester concentration in light oil from the peak area. Got.
The methyl ester concentration (% by weight) in the sample was determined from the calibration curve.

(3) Calculation method of methyl ester conversion rate The conversion rate of methyl ester was calculated | required with the following formula.
Methyl ester conversion rate (%) = (sample methyl ester concentration / oil concentration before reaction) × 100
The pre-reaction oil / fat concentration is an oil / fat content concentration when the organic solvent added during the reaction and the oil / fat in the waste clay are uniform, and is calculated by the following calculation formula.
Oil / fat concentration before reaction (%) = [A / (A + B)] × 100
A is the weight of fats and oils in bleached soil (g)
B is the weight of organic solvent added before the reaction (g)

(4) Ignition loss of zeolite The ignition loss was determined by calcining the sample at 860 ° C. for 30 minutes and then allowing to cool, and quantifying from the reduction.
The ignition loss of each zeolite used in Examples and Comparative Examples is as follows.
Ignition loss 4A type zeolite 22.3% by weight
5A type zeolite 21.7% by weight
Y-type zeolite 25.7% by weight

(5) BET specific surface area
Measurement was performed using a Tri Star 3000 manufactured by Micromeritics. Analysis was performed by the BET method from an adsorption branch side nitrogen adsorption isotherm having a specific pressure of 0.05 to 0.35 or less.

(Comparative Example 1)
A 500 ml Erlenmeyer flask was mixed with 68 g of waste clay containing 33% by weight of fat and oil used for refining palm oil, 3.1 g of methanol, 54.7 g of light oil, and 0.068 g of lipase (Lipase-QLM manufactured by Meitsu Sangyo) and stirred at 25 ° C. While reacting. Samples were sampled every 24 hours and the methyl ester conversion rate was measured. The results are shown in Table 1.

Example 1
1.4 g of 4A-type zeolite was added to the same formulation as Comparative Example 1 and reacted in the same manner as Comparative Example 1. The results are shown in Table 1. Moreover, Na content in the obtained biofuel was calculated | required based on the reference | standard oil-and-fat analysis test method (The Japan Petrochemical Society edition) 2.6.2-1996. As a result, the Na content was less than the detection limit (5 ppm).

(Example 2)
To the same formulation as Comparative Example 1, 1.4 g of reagent sodium carbonate was added and reacted in the same manner as Comparative Example 1. The results are shown in Table 1.

(Comparative Example 2)
1.4 g of a cation exchange resin (DOWEX 50W manufactured by Dow Chemical Co., Ltd.) was added to the same formulation as in Comparative Example 1 and reacted in the same manner as in Comparative Example 1. The results are shown in Table 1.

(Comparative Example 3)
1.4 g of an anion exchange resin (IRA-400J, manufactured by Rohm and Haas) was added to the same formulation as Comparative Example 1, and reacted in the same manner as Comparative Example 1. The results are shown in Table 1.

(Comparative Example 4)
1.4 g of reagent sodium bicarbonate was added to the same formulation as Comparative Example 1 and reacted in the same manner as Comparative Example 1. The results are shown in Table 1.

(Comparative Example 5)
After thoroughly mixing 200 g of waste clay used for refining palm oil and 1 kg of hexane, the hexane phase was separated, and hexane was distilled off with a rotary evaporator to obtain a waste clay extract oil. To 28 g of the obtained extracted oil, 3.6 g of methanol, 51 g of light oil, 0.084 g of lipase (Lipase-QLM manufactured by Meito Sangyo Sangyo), and 1.9 g of 4A zeolite were added and mixed, and reacted at 25 ° C. with stirring. . The results are shown in Table 2.

(Comparative Example 6)
In the same formulation as Comparative Example 5, the reaction was conducted in the same manner with the amount of lipase added being 0.84 g. The results are shown in Table 2.

(Comparative Example 7)
In the same formulation as Comparative Example 5, 1.9 g of reagent sodium carbonate was added instead of 4A zeolite and reacted in the same manner. The results are shown in Table 2.

(Example 3)
93.4 g of waste white clay used in Comparative Example 5 (oil content 28 g), 3.6 g of methanol, 51 g of light oil, 0.084 g of lipase, and 1.9 g of 4A zeolite were mixed and reacted in the same manner as in Comparative Example 5. The results are shown in Table 2.

Example 4
In the same formulation as in Example 3, 1.9 g of reagent sodium carbonate was added in place of 4A zeolite and reacted in the same manner. The results are shown in Table 2.

(Example 5)
In a 500 ml Erlenmeyer flask, 68 g of waste white clay with 34% by weight of fat and oil used for refining palm oil, 3.1 g of methanol, 54.7 g of light oil and 0.068 g of lipase (Lipase-QLM manufactured by Meito Sangyo Sangyo) 4 g was mixed and reacted at 25 ° C. with stirring. Samples were sampled every 24 hours and the methyl ester conversion rate was measured. The results are shown in Table 3.

(Example 6)
The reaction was carried out in the same manner as in Example 5 except that the amount of 4A zeolite added was 3.4 g. The results are shown in Table 3.

(Example 7)
The reaction was carried out in the same manner as in Example 5 except that the amount of zeolite 4A added was 6.8 g. The results are shown in Table 3.

(Example 8)
The reaction was carried out in the same manner as in Example 5 except that the amount of zeolite 4A added was 13.6 g. The results are shown in Table 3.

(Comparative Example 8)
In the same formulation as Comparative Example 5, 1.9 g of γ-alumina (MGA manufactured by Mizusawa Chemical Co., Ltd. (BET specific surface area 194 m ^{2 /} g)) was added in place of the 4A-type zeolite and reacted in the same manner. The results are shown in Table 4.

Example 9
In the same manner as in Example 3, 1.9 g of γ-alumina (Mizusawa Chemical Industries MGA (BET specific surface area 194 m ² / g)) was added in place of 4A zeolite and reacted in the same manner. The results are shown in Table 4.

(Example 10)
1.4 g of boehmite (BET specific surface area of 88 m ² / g) was added to the same formulation as in Comparative Example 1 and reacted in the same manner as in Comparative Example 1. The results are shown in Table 5.

(Example 11)
To the same formulation as in Comparative Example 1, 1.4 g of pseudoboehmite (CATALOX (BET specific surface area 184 m ² / g) manufactured by SASOL) was added and reacted in the same manner as in Comparative Example 1. The results are shown in Table 5.

Example 12
To the same formulation as Comparative Example 1, 1.4 g of boehmite (Catapal C (BET specific surface area 243 m ² / g) manufactured by SASOL) was added and reacted in the same manner as Comparative Example 1. The results are shown in Table 5.

(Example 13)
1.4 g of boehmite (Tomita AD220P (BET specific surface area 290 m ² / g)) manufactured by Tomita Pharmaceutical Co., Ltd. was added to the same formulation as Comparative Example 1, and reacted in the same manner as Comparative Example 1. The results are shown in Table 5.

(Example 14)
1.4 g of γ-alumina (Nippon Light Metal C20 (BET specific surface area 198 m ² / g)) was added to the same formulation as Comparative Example 1, and reacted in the same manner as Comparative Example 1. The results are shown in Table 5.

(Example 15)
1.4 g of γ-alumina (Mizusawa Chemical Industry GP-20 (BET specific surface area 243 m ² / g)) was added to the same formulation as Comparative Example 1 and reacted in the same manner as Comparative Example 1. The results are shown in Table 5.

(Example 16)
1.4 g of γ-alumina (Mizusawa Chemical Industries MGA (BET specific surface area 194 m ² / g)) was added to the same formulation as Comparative Example 1 and reacted in the same manner as Comparative Example 1. The results are shown in Table 5.

(Example 17)
1.4 g of a composite oxide of silica and magnesia (Mizuka Life F-2G (weight ratio SiO ₂ : MgO = 78: 22) manufactured by Mizusawa Chemical Industry Co., Ltd.) was added to the same formulation as in Comparative Example 1 and reacted in the same manner as in Comparative Example 1. The results are shown in Table 5.

(Example 18)
1.4 g of 5A zeolite was added to the same formulation as Comparative Example 1, and reacted in the same manner as Comparative Example 1. The results are shown in Table 5.

(Comparative Example 9)
A 500 ml Erlenmeyer flask was mixed with 68 g of waste white clay with a fat content of 36% by weight used for refining palm oil, 3.4 g of methanol, 54.7 g of light oil and 0.068 g of lipase (Lipase-QLM manufactured by Meitsu Sangyo) and stirred at 25 ° C. While reacting. A sample was sampled after 168 hours, and the methyl ester conversion rate was measured. The results are shown in Table 6.

(Examples 19 and 20)
1.4 g of A-type zeolite or Y-type zeolite was added to the same formulation as Comparative Example 9 and reacted in the same manner as Comparative Example 9. The results are shown in Table 6.

(Comparative Examples 10-12)
To the same formulation as Comparative Example 9, 1.4 g of X-type zeolite, natural mordenite or natural clinoptilolite was added and reacted in the same manner as Comparative Example 9. Table 6 shows the methyl ester conversion rate (%) after 168 hours.

Claims (11)

In the method for producing a biofuel, the waste white clay dispersed in an organic solvent is reacted with a lower monohydric alcohol in the presence of an enzyme to give an ester.
A method for producing a biofuel, wherein the reaction is performed in the presence of at least one reaction accelerator selected from the group consisting of an alkaline inorganic compound and aluminum oxide or hydroxide.   The method according to claim 1, wherein the enzyme is added in an amount of 0.01 to 1.0 part by weight and the reaction accelerator is added in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the waste clay. .   The manufacturing method according to claim 1, wherein a metal-containing alkaline inorganic compound belonging to Group 1 and / or 2 of the Periodic Table is used as the alkaline inorganic compound.   The production method according to claim 3, wherein zeolite or sodium carbonate is used as the alkaline inorganic compound.   The production method according to claim 4, wherein A-type zeolite is used as the zeolite.   The production method according to claim 4, wherein the zeolite has a loss on ignition at 860 ° C of 15% by weight or more. The manufacturing method of Claim 1 which uses the aluminum oxide thru | or hydroxide whose BET specific surface area is 100 m < ² > / g or more as said aluminum oxide thru | or hydroxide.   The production method according to claim 1, wherein the reaction is carried out at 20 to 50 ° C.   The manufacturing method of Claim 1 which uses lipase as an enzyme.   The production method according to claim 1, wherein methanol is used as the lower monohydric alcohol.   The organic solvent, waste clay, enzyme, lower monohydric alcohol and reaction accelerator are put into a reaction vessel and mixed by stirring to react the fats and oils in the waste clay with lower monohydric alcohol to produce an ester. The method for producing biofuel according to claim 1.