KR102057143B1 - Method for producing bioalcohol using reactant having linear voids for producing biofuels - Google Patents

Abstract

The present invention relates to a method for producing a biofuel, and more particularly, to a manufacturing method capable of significantly improving the yield while significantly reducing the time required for producing a biofuel. In the present invention, the process of converting a mixture of volatile fatty acids and aliphatic alcohols into fatty acid alkyl esters is carried out under a reactant having linear pores, whereby the linear pores give directivity to the conversion process, thereby reducing the conversion time to several seconds. Can be. Therefore, the present invention is expected to significantly reduce the time required for the production of biofuels, and significantly improve the economics of the production of biofuels.

Description

Method for producing biofuel using reactant having linear pores {METHOD FOR PRODUCING BIOALCOHOL USING REACTANT HAVING LINEAR VOIDS FOR PRODUCING BIOFUELS}

The present invention relates to a method for producing a biofuel, and more particularly, to a manufacturing method capable of significantly improving the yield while significantly reducing the time required for producing the biofuel.

As fossil fuels are known to be the main cause of climate change, such as global warming, the move to limit the use of fossil fuels, such as the introduction of carbon taxes and renewable energy mandates, is accelerating.

In line with this move, biofuels are emerging as new sources of renewable energy. In particular, bio-alcohol has attracted attention as environmentally friendly energy because it emits less environmental pollutants than fossil fuels.

Biofuel refers to a fuel produced by pyrolyzing or fermenting living organisms such as plants, microorganisms, and animals, food waste, and livestock waste that are energy sources capable of producing bioenergy.

On the other hand, the process of generating biofuels is generally divided into a pretreatment process using an acid catalyst (H ₂ SO ₄ ) and the present process using a base catalyst (KOH, NaOH). The pretreatment process requires a long reaction time of at least 30 hours and the process at least 2 hours. In addition, it is carried out in a batch type (batch type) rather than a continuous, there is a limit in the amount of production in one process. In addition, the conventional process as described above has a problem in that a large amount of wastewater is generated because a washing process using hot water is essential due to the use of an acid catalyst and a base catalyst.

That is, according to the conventional method, the production of bioalcohol takes too much time and the yield is not good, and the problem of wastewater treatment remains, and the bioalcohol was not easy to replace fossil fuel.

In order to solve this problem, a supercritical transesterification process is performed in which methanol or ethanol and fats and oils are reacted under high pressure conditions of 120 ° C to 250 ° C and 50 bar to 200 bar to directly obtain fatty acid alkyl esters (FAMEs). Developed. However, in the supercritical transesterification reaction, alcohols require excessive amounts, such as fats and fats, from 20: 1 to 40: 1, which can only be reacted batchwise. As a result, the production of biofuels through supercritical transesterification is still at the stage of research and development, and has not advanced to commercialization.

Therefore, there is a need for an environment-friendly and economical biofuel production method that can shorten the production time and improve the yield without generating wastewater.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and significantly reduces the time for converting a mixture of volatile fatty acids (VFAs; Volatile Fatty Acids) and aliphatic alcohols having 1 to 12 carbon atoms into fatty acid alkyl esters without acid catalysts or base catalysts. It is intended to provide a method for preparing biofuel.

On the other hand, other unspecified objects of the present invention will be further considered within the range that can be easily inferred from the following detailed description and effects thereof.

Biofuel production method according to an embodiment of the present invention for achieving the above object comprises the steps of preparing a mixture by mixing volatile fatty acids and aliphatic alcohols having 1 to 12 carbon atoms; And esterifying the mixture under a reactant having linear pores that can be introduced with aromaticity to produce fatty acid alkyl esters.

In this case, the rate and yield of the esterification reaction varies according to the shape of the reactant, wherein the reactant includes a plurality of microtubules, and the pores may include a space into which the mixture is introduced into the microtubules. have.

Alternatively, the reactant may include a plurality of microtubes, and the pores may include a first space in which the mixture flows into the microtubes, and the plurality of microtubes may be arranged in a dense structure, thereby forming outer walls of the plurality of microtubes. It may include a second space formed by.

Alternatively, the reactant may include a plurality of microfibers, and the pores may include a space formed by outer walls of the plurality of microfibers by arranging the plurality of microfibers in a dense structure.

For example, the reactant may be carbon nanotubes.

Alternatively, the pore contained in the reactant may be a trench. In this case, the trench may be formed by anodizing a metal tube.

According to the present invention, in the step of preparing the mixture, the volume ratio of the volatile fatty acids and the alcohols may be mixed to be 0.3: 1 to 1: 1.

In addition, the step of producing the fatty acid alkyl ester may be carried out at a temperature of 200 ℃ to 400 ℃. Preferably, the step of producing the fatty acid methyl ester may be carried out at a temperature of 350 ℃ to 400 ℃.

On the other hand, the present invention may further comprise the step of producing a bio-alcohol by hydrogenating the produced fatty acid alkyl ester. At this time, in the step of preparing the bio-alcohol, the hydrogenation reaction may be performed under a transition metal catalyst (for example, a cobalt catalyst supported on silica).

In the present invention, a mixture of volatile fatty acids and aliphatic alcohols having 1 to 12 carbon atoms is used to generate fatty acid alkyl esters by esterification using a reactant having linear pores, thereby significantly reducing the time required for the esterification reaction. Rather, biofuel yields could be improved. In addition, since the present invention does not use an acid catalyst or a base catalyst, waste water does not occur, which is environmentally friendly, and biofuels can be produced in a continuous manner rather than batchwise.

On the other hand, even if the effects are not explicitly mentioned here, it is added that the effects described in the following specification and the provisional effects expected by the technical features of the present invention are treated as described in the specification of the present invention.

1 is a schematic flowchart of a method of manufacturing a biofuel according to an embodiment of the present invention.
Figure 2 is a schematic diagram illustrating a process of the esterification reaction in the pores of the reactants used for the esterification reaction of the biofuel manufacturing method according to an embodiment of the present invention.
3 is a schematic perspective view showing the shape of various kinds of reactants.
4 is a result of measuring the reaction rate (reaction rate) of the esterification reaction according to the type of reactant shown in FIG.
5 is a result of measuring the conversion rate of volatile fatty acids according to the reaction temperature of the esterification reaction.
6 is a schematic perspective view showing that the metal tube has trench-shaped pores.
7 is a result of measuring the yield of bio alcohol according to the type of catalyst used in the hydrogenation reaction.
8 is a result of measuring the yield of bio-alcohol over time when the hydrogenation reaction is carried out.
The accompanying drawings show that they are illustrated as a reference for understanding the technical idea of the present invention, by which the scope of the present invention is not limited.

In the following description of the present invention, when it is determined that the subject matter of the present invention may be unnecessarily obscured by the person skilled in the art with respect to the related well-known functions, the detailed description will be omitted.

The present invention relates to a method for preparing a biofuel using volatile fatty acids (VFAs) and methanol. In particular, in the present invention, volatile fatty acids may be converted from organic waste.

In general, bioalcohol is manufactured using carbohydrate as a raw material, but the present invention has advantages in that all carbohydrates, fats, and proteins contained in organic wastes can be used because the volatile fatty acids converted from wastes are converted into bioalcohols.

In the present invention, for the sake of convenience of description, butanol acid is used for the production of butanol, but the scope of the present invention is not limited to butyric acid.

Hereinafter, a method of manufacturing a biofuel will be described with reference to the accompanying drawings.

1 is a schematic flowchart of a method of manufacturing a biofuel according to an embodiment of the present invention.

Referring to the drawings, a method of manufacturing a biofuel according to an embodiment of the present invention comprises the steps of preparing a mixture by mixing volatile fatty acids and aliphatic alcohols having 1 to 12 carbon atoms (S110) and the mixture may be introduced with aromaticity And esterifying under a reactant having linear pores, thereby producing a fatty acid alkyl ester (S120). Furthermore, one embodiment of the present invention may further comprise the step of producing a bio-alcohol by hydrogenation of the resulting fatty acid alkyl ester (S130).

That is, biodiesel or bioalcohol can be obtained by using the manufacturing method of the biofuel of this invention.

In one embodiment of the present invention, the volatile fatty acid is acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, valeric acid, and isovaleric acid. isovaleric acid) or any combination thereof.

Moreover, as alcohol, C1-C12 aliphatic alcohol can be used. For example, as alcohols, any one selected from the group consisting of methanol, ethanol, propanol, butanol and pentanol or a combination thereof can be used. Of these, methanol and ethanol may be preferred in terms of economics, and methanol is most preferable in consideration of reactivity. In the case of methanol (MeOH), the reactivity can be improved by the reactivity and the compound structural factors (Steric). In addition, it is possible to increase the number of carbon molecules of fatty acid alkyl esters produced by using alcohols having high carbon number, and to change the physical properties of fatty acid alkyl esters produced by using various kinds of alcohols.

First, a step (S110) of preparing a mixture by mixing volatile fatty acids and aliphatic alcohols having 1 to 12 carbon atoms is performed. Preparing the mixture (S110) may be stirred at about 800 rpm using a mixer. On the other hand, when the reactants are in a form that can be mixed in the mixture, the reactant may be added to the mixture at the same time or after the step (S110) of preparing the mixture.

At this time, the volatile fatty acids and alcohols may be mixed in a volume ratio of 0.3: 1 to 1: 1, preferably 0.3: 1 to 0.5: 1. In this manner, the conversion to fatty acid alkyl esters can be improved by adjusting the volume ratio of volatile fatty acids and alcohols.

Next, a step (S120) of esterifying a mixture of volatile fatty acids and alcohols under a reactant to produce a fatty acid alkyl ester is performed.

 In the present invention, the esterification reaction is carried out at 200 ° C to 400 ° C, preferably at 350 ° C to 400 ° C. In this case, the temperature increase rate may be performed at 20 ℃ to 30 ℃ per minute, but is not limited thereto.

On the other hand, the reaction may be carried out at an initial pressure of 1 atm. However, the present invention is not limited thereto, and the pressure may be increased or decreased as necessary.

The present invention is characterized in that the esterification reaction is carried out under the reactant instead of using an acid catalyst or a base catalyst.

In particular, the reactants used in one embodiment of the present invention is characterized in that the mixture has a linear pores that can be introduced with a directivity.

In one embodiment of the present invention, the esterification reaction is induced by increasing the collision frequency and strength of the molecules of volatile fatty acids and alcohols in the pores of the reactants. At this time, the size of the pore should be large enough to allow volatile fatty acids to flow in and collide with alcohols. That is, the size of the pore may be determined by what kind of volatile fatty acid is used, and in the case of using various kinds of volatile fatty acids, the size of the pore may be determined based on the largest volatile fatty acid.

2 schematically shows the esterification reaction in the pores 2 of the reactant 1 of the embodiment of the present invention.

As can be seen in Figure 2, in one embodiment of the present invention, the esterification reaction is carried out in the pores (2) of the volatile fatty acids and alcohols (for example, MeOH) reactant (1), The esterification reaction of one embodiment is achieved by increasing the number of collisions through a limited space called voids 2 and raising the temperature from 200 ° C. to 400 ° C. to increase the kinetic energy of the molecule.

In particular, the reactants used in one embodiment of the present invention are characterized by having linear pores through which the mixture can flow in a direction. In other words, the researchers of the present invention found that the rate of esterification reaction increased significantly when the pores 2 had a linear shape, and applied them to the production of biofuels.

In this case, the directional flow means that the linear void includes a configuration in which the inlet and the outlet serve. In other words, having directionality is not a spot and does not necessarily require it to be straight. However, the closer it is to a straight line, the more aligned it is.

Looking at the esterification reaction of an embodiment of the present invention, the fatty acid alkyl ester as a reaction product is drawn out of the pores of the reactant in the gas phase due to the reaction temperature. In this case, when the mixture is not a linear pore to allow the flow in a direction, there is a problem that the reaction efficiency is low because the mixture is introduced and the reaction product flows out.

This problem becomes clearer with reference to FIG. 3.

3 illustrates a reactant having various shapes. The reactant shown in FIG. 3 is formed using carbon nanotubes.

Referring to FIG. 3, the reactant has a form in which a plurality of microfibers are entangled (Comparative Example 1, FIG. 3A), a form in which a plurality of microfibers are arranged in a dense structure (Example 1, FIG. 3B), and a plurality of microtubules. It may be in an entangled form (Example 3, FIG. 3C), or in a form in which a plurality of microtubules are arranged in a dense structure (Example 4, FIG. 3D).

The space | gap of the comparative example 1 includes the space 30a by which the some microfiber 21a is entangled. The voids of Comparative Example 1 do not have directivity as shown in FIG. 3A. The surface area of the reactant of Comparative Example 1 is 1020 m 2 / g, the volume of the pores is 1.1 cm 3 / g, and the diameter of the pores is 4.0 nm.

The cavity of Example 1 includes a space 30b in which a plurality of fine fibers 21b are arranged in a dense structure and formed by outer walls of the plurality of fine fibers. As shown in FIG. 3B, the air gap of Example 1 has a linear shape that is elongated together in a direction in which the microfibers 21b are formed long, and by having such a shape, the mixture may be introduced with a directivity. The surface area of the reactant of Example 1 is 1120 m 2 / g, the volume of the pores is 1.1 cm 3 / g, and the diameter of the pores is 3.8 nm.

 The space | gap of Example 2 includes the 1st space 31c located in the inside of the some microtube 21c, and the 2nd space 21c by which the some microtubule 21c is entangled. The first space 31c means a space inside the tube, and has a linear shape formed along the microtubule 21c, and the second space 32c does not have directivity as shown in FIG. 3C. The surface area of the reactant of Example 2 was 1740 m 2 / g, the volume of the pores was 1.9 cm 3 / g, and the diameters of the pores were 3.5 nm and 4.8 nm.

The void of Example 3 is a second space formed by the outer walls of the plurality of microtubes, in which the first space 31d and the plurality of microtubes 21b positioned inside the plurality of microtubes 21d are aligned in a dense structure. Space 31d. The first space 31d means a space in the tube, and has a linear shape formed along the microtubule 21d, and the second space 32d is elongated together in the direction in which the microtubule 21d is formed long. It has a linear shape, and by having such a shape, the mixture can be induced to flow in a direction. The surface area of the reactant of Example 3 is 1630 m 2 / g, the volume of the pores is 1.5 cm 3 / g, and the diameters of the pores are 3.2 nm, 4.4 nm.

4 is a result of measuring the reaction rate of the esterification reaction while the esterification reaction using the reactants shown in FIG.

For the experiment of FIG. 4, butyric acid was used as volatile fatty acid, methanol was used as aliphatic alcohol, and the volume ratio of volatile fatty acid and alcohol was 0.5: 1. The reaction was carried out at T = 200 ℃, P ₀ = 1 atm, the measurement results are the average of three repeated measurements.

Referring to FIG. 4, it can be seen that the reaction rate measured under the reactant of Examples is at least three times higher than the reaction rate measured under the reactant of Comparative Example 1.

In particular, it can be seen that the surface area, the volume of the pores, the diameter of the pores and the measurement result of FIG. 4 are not perfectly proportional, which proves that the shape of the reactant is the main factor determining the reaction rate.

In detail, the first space 31d and the plurality of microtubes 21b positioned inside the plurality of microtubes 21d are aligned in a dense structure to form a second space formed by the outer walls of the plurality of microtubes ( It can be seen that the reactant of Example 3 containing 31d) as a void has the highest reaction rate. That is, the case where the voids have a high orientation and aligned shapes has a higher reaction rate.

Next, the high reaction rate was obtained by using the reactant of Example 1 including a space 30b formed by the outer walls of the plurality of microfibers as voids. Example 1 having a higher reaction rate than Example 2 illustrates the effect of the ordered degree of directional pores on the reaction rate. That is, in Example 2, the reaction rate of Example 1 is lower because the alignment of the pores is lower than that of Example 1 due to the separation of the linear tubes due to the microtubules, the bending of the microtubules, and the kinks. It was measured faster than the reaction rate of Example 2.

In conclusion, the method for preparing a biofuel according to an embodiment of the present invention may significantly increase the reaction rate of an esterification reaction by esterifying the mixture under a reactant having a linear pore into which the mixture can be introduced with aromaticity. In particular, the time required for the esterification reaction can be reduced to a few seconds. Accordingly, the method for producing a biofuel according to an embodiment of the present invention can be used for continuous production.

Meanwhile, the reactants of Examples 1 to 3 may be formed using a carbon material (for example, carbon nanotubes), but are not limited thereto. However, in the present invention, the shape of the void is most important, but the carbon material has an advantage in that it is easy to produce a desired shape.

In addition, the method for producing a biofuel according to an embodiment of the present invention can significantly improve the conversion rate to fatty acid alkyl ester as well as the reaction rate.

Table 1 below performs the esterification reaction under the reactant of Example 3. To volatile fatty acids in the acid, alcohol was used as a methanol, an initial reaction pressure P ₀ = 1 atm, respectively. The volume ratio means volatile fatty acids / alcohols (v / v). In addition, Figure 5 shows the conversion rate of the volatile fatty acids of Samples 2 to 8 in Table 1 below in a graph.

Sample Reaction temperature (℃) Volume ratio VOC Conversion Rate (%) One 200 0.5 16.4 2 240 0.5 36.5 3 270 0.5 53.2 4 300 0.5 69.2 5 320 0.5 79.8 6 340 0.5 88.8 7 360 0.5 92.4 8 380 0.5 92.4 9 360 0.3 94.5 10 360 One 83.3 11 360 2 52.2 12 360 3 22.2

Referring to Table 1 and Figure 5, the esterification of the biofuel manufacturing method according to an embodiment of the present invention is carried out at 200 ℃ to 400 ℃, preferably may be carried out at 350 ℃ to 400 ℃. In particular, looking at samples 6 to 8, it can be seen that the conversion of volatile fatty acids, that is, the yield of fatty acid alkyl esters, exceeds 90%.

At this time, the volatile fatty acids and alcohols can be maximized the yield of fatty acid alkyl ester by mixing in a volume ratio of 0.3: 1 to 1: 1, preferably 0.3: 1 to 0.5: 1.

On the other hand, as described above, the method for producing a biofuel according to an embodiment of the present invention may have a reaction rate of several seconds by esterification under a reactant having linear pores, which may be used in a continuous manufacturing process. Can be.

The reactant used in the biofuel production method according to the embodiment of the present invention may be used a surface-treated metal tube to be suitable for the continuous manufacturing process. At this time, trenches are formed in the surface of the metal tube. The metal tube may be an aluminum tube or a steel tube, but is not limited thereto. However, the present invention is not limited to the metal tube, and it is sufficient that the present invention can form a linear trench-shaped gap of appropriate size. For example, a metal plate may be used, and a semiconductor wafer or the like may be used except for economic problems.

6 is a schematic perspective view showing the metal tube having trench-shaped pores;

Referring to FIG. 6, the metal tube 40 has trench-shaped voids 41 formed on the inner or outer surface with a predetermined depth. The trench-shaped voids 41 may be formed linearly rather than in the form of spots. Such a gap 41 may be formed by anodizing a metal tube. At this time, the inside of the metal tube does not serve as a void, but the trench formed on the surface of the metal tube serves as a void. That is, the inside of the metal tube does not mean the void in the present invention, but the trench formed on the surface of the metal tube means the void in which the esterification reaction is performed in the present invention.

By using a metal tube having a trench-shaped linear pore in the reactant of the method for producing a biofuel according to an embodiment of the present invention, a mixture of volatile fatty acids and alcohols is passed through the metal tube at a high temperature to perform an esterification reaction. can do. In particular, the method for producing a biofuel according to an embodiment of the present invention can significantly improve the reaction rate by performing an esterification reaction using a reactant having a linear pore, and thus a mixture of volatile fatty acids and alcohols at a high temperature. Just passing through the metal tube at will induce the desired degree of esterification.

Further, the reactant of the method of manufacturing a biofuel according to an embodiment of the present invention is not limited to a metal tube, but may have a linear pore provided with directivity by surface treatment of the reactant. As the surface treatment for imparting linear voids to the surface of the reactant, chemical and physical methods such as anodizing and polishing may be used. It is important to note, however, that these methods must be able to form linear pores on the surface of the reactant.

As described above, the mixture is esterified under a reactant having linear pores that can be introduced with aromaticity to generate a fatty acid alkyl ester (S120), followed by hydrogenation of the produced fatty acid alkyl ester to bio Preparing the alcohol (S130) may be further performed.

At this time, the hydrogenation reaction may be carried out under a transition metal catalyst.

The transition metal catalyst may be any one selected from Group 8 to 11 metals on the periodic table. For example, the transition metal catalyst may be one of copper, chromium, zinc, aluminum, and cobalt supported on alumina, silica, silica-alumina, zeolite, mesoporous silica, SAPO, or AlPO carrier.

7 is a result of measuring the yield of bio alcohol according to the type of catalyst used in the hydrogenation reaction, it can be seen that using the cobalt catalyst supported on silica as a catalyst shows the highest yield. In particular, it can be seen that using a cobalt catalyst shows higher efficiency than using another expensive catalyst.

The hydrogenation reaction can be carried out at a temperature of 200 ℃ to 300 ℃, the temperature increase rate can be set to 10 ℃ to 30 ℃ per minute. In addition, the initial pressure may be 10 to 100 atm.

The time at which the hydrogenation reaction is carried out may be performed at least 1 hour to 15 hours, preferably between 10 hours and 15 hours to obtain the maximum yield (see FIG. 8).

In view of the above, it is thought that the biofuel may be further commercialized by using the biofuel production method according to an embodiment of the present invention. In particular, the method for producing a biofuel according to an embodiment of the present invention significantly improved the reaction rate of the esterification reaction, thereby reducing the 2-3 hours required for the conventional esterification reaction to several seconds.

Furthermore, the method for manufacturing a biofuel according to an embodiment of the present invention may continuously manufacture the biofuel.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is again noted that the scope of protection of the present invention may not be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

Claims (13)

Preparing a mixture by mixing volatile fatty acids and aliphatic alcohols having 1 to 12 carbon atoms; And
And esterifying the mixture under a reactant having linear pores that can be introduced with aromaticity to produce fatty acid alkyl esters.
The reactant is characterized in that the carbon nanotubes,
Method of producing biofuel.
The method of claim 1,
The reactant includes a plurality of microtubules,
The air gap is characterized in that it comprises a space located inside the microtubule,
Method of producing biofuel.
The method of claim 1,
The reactant includes a plurality of microtubules,
The gap includes a first space located inside the microtube and a second space formed by the outer walls of the plurality of microtubes by aligning the plurality of microtubes in a dense structure,
Method of producing biofuel.
The method of claim 1,
The reactant includes a plurality of microfibers,
The voids are characterized in that it comprises a space formed by the outer wall of the plurality of fine fibers by the plurality of fine fibers are arranged in a dense structure,
Method of producing biofuel.
delete delete delete delete The method of claim 1,
Producing the fatty acid alkyl ester, characterized in that carried out at a temperature of 200 ℃ to 400 ℃,
Method of producing biofuel.
The method of claim 1,
In preparing the mixture,
The volume ratio of the volatile fatty acids and the alcohols is characterized in that 0.3: 1 to 1: 1,
Method of producing biofuel.
The method of claim 1,
Producing the fatty acid alkyl ester,
Further comprising the step of producing a bio-alcohol by hydrogenating the produced fatty acid alkyl ester,
Method of producing biofuel.
The method of claim 11,
In the step of preparing the bio alcohol,
The hydrogenation reaction is characterized in that carried out under a transition metal catalyst,
Method of producing biofuel.
The method of claim 12,
The transition metal catalyst is characterized in that using a cobalt catalyst supported on silica,
Method of producing biofuel.

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