KR101143313B1 - Biodiesel production equipment separating glycerol by membrane bioreactor - Google Patents

Abstract

PURPOSE: A device for removing glycerol using a membrane bioreactor is provided to continuously remove glycerol and to reduce enzyme activity. CONSTITUTION: A device for producing biodiesel comprises a reactor for producing biodiesel and glycerol by reacting glyceride and C1-C5 alcohol by fixed lipase, and a membrane module. In the membrane module, a reaction mixture solution flows into one section partitioned by a membrane, moves in parallel with the membrane, and flows out; separately, C1-C5 alcohol flows into the other section partitioned by the membrane, moves in parallel with the membrane, and flows out. The membrane module has pore size of 5~35 MWCO and is formed of regenerative cellulose. The lapase is Candida Antarctica B lipase.

Description

Biodiesel Production Equipment Separating Glycerol by Membrane Bioreactor to Remove Glycerol by Membrane Bioreactor

The present invention relates to an apparatus for removing glycerol using a membrane bioreactor during a transesterification reaction for biodiesel production. The transesterification reaction mixture and the C ₁ to C ₅ alcohol phases are separated by regenerated cellulose with membrane modules. In this way inhibition by glycerol produced continuously can be reduced and C ₁ to C ₅ alcohols can be fed continuously using a hydrophilic membrane. Furthermore, the present invention aims to improve the productivity of biodiesel for a short working time.

Biodiesel is defined as monoalkylesters of long chain fatty acids derived from vegetable oils or animal fats. It is formed by transesterification of plant oils with methanol or other short chain alcohols (FIG. 1). Biodiesel is a renewable resource unlike diesel from petroleum. The advantages of biodiesel are many, including carbon dioxide neutral, low sulfur content, non-toxicity, biodegradability, and non-locality of resources, and can be based on a variety of sources.

Catalysts for transesterification include acids, bases as well as free or immobilized enzymes. The most common method of producing biodiesel is using alkali as a catalyst. For the production of biodiesel, alkali-catalyst methods have been established because of the high conversion of oil to methylester. The limitation of this method is due to the purity of the reactants, the sensitivity of the method to fatty acids as well as the moisture concentration of the sample.

Large scale commercial continuous alkali-catalyst processes require high pressure and high temperature. However, this method requires a lot of energy and expensive equipment, and is limited by its weak stability.

The most important limitation of the alkali-catalyst process is saponification during the reaction, which makes it difficult to recover downstream and purify the biodiesel.

Problems of alkali-catalyst methods such as energy-concentration, wastewater treatment, and difficulty in recovering glycerol can be overcome with lipase-catalyst methods.

The three main components of the lipase-catalyst process are oil and alcohol as substrates and lipase as catalyst. Unlike alkaline catalysts, enzymes can be esterified in one step without soap formation and subsequent washing steps. Lipases used to produce biodiesel from oil have no stereospecificity, so that tri-, di- and mono-glycerides can all be converted to fatty acid methyl esters (FAMEs). A wide range of lipases can be used for enzymatic transesterification.

In addition to the types of lipases, other factors affecting the efficiency of lipases in producing biodiesel from oils include water content, temperature, cycles of immobilized lipase, and the type and ratio of alcohols to the oil. have.

Lipase-catalyst methods have not been implemented on a commercial scale because of limitations such as enzyme inhibition by methanol, degradation of enzyme activity and high price of enzymes. In addition, continuous biodiesel production using enzymes has also been reported on a laboratory scale.

Glycerol, on the other hand, has been reported to reduce the activity of immobilized enzymes. Therefore, it is desirable to remove glycerol during the reaction in order to reduce the effect of glycerol produced.

This effect of glycerol is due to the restriction of mass transfer in the immobilized enzyme, specifically, because large molecules such as oil or FAME is difficult to diffuse to the small pores where the enzyme is located, methanol is dissolved in a very small amount in the oil-filled pores.

During biodiesel production, glycerol forms a hydrophilic phase, which does not mix completely with oil and forms a film layer around the immobilized enzyme. In addition, this hydrophilic phase functions as a partition for the alcohol from the oil phase, which leads to a lower concentration of alcohol in the reaction medium and at the same time to a lower conversion. This glycerol-alcohol insoluble phase inhibits the enzymatic reaction.

Therefore, there is an urgent need for industrialization of biodiesel production, in which a new type of production model capable of preventing the degradation of enzyme activity by alcohols such as methanol as a reactant and glycerol as a product is prevented.

The present invention has been made to solve the above problems, a reactor for converting glycerides and C ₁ to C ₅ alcohol to biodiesel and glycerol through a lipase catalyst, and to remove the glycerol in the reaction mixture and to C ₁ to It is an object to provide a biodiesel production apparatus comprising a membrane module for supplying C ₅ alcohol to the reaction mixture.

Biodiesel production apparatus of the present invention in order to achieve the object as described above,

A reactor for producing biodiesel and glycerol by reacting glycerides and C ₁ to C ₅ alcohols with an immobilized lipase; And

The reaction mixture flowed out from the reactor is introduced into one area divided into membranes and moved in parallel with the membrane, and then flowed out. Separately, C ₁ to C ₅ alcohol is introduced into the other region separated by the membrane and Membrane module spilled after moving in parallel

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A portion of the glycerol in the reaction mixture is characterized in that the permeation of the C ₁ to C ₅ alcohol flows in the region divided by the membrane.

In addition, a part of the C ₁ to C ₅ alcohol may be permeated to the region in which the reaction mixture flows among the regions separated by the membrane.

In addition, the reactor may be a continuous type in which glyceride or glyceride and C ₁ to C ₅ alcohol are continuously introduced and the reaction mixture is continuously discharged.

In addition, the direction in which the reaction mixture flows in the membrane module and the direction in which the C ₁ to C ₅ alcohols flow may be opposite directions.

In addition, the membrane module may comprise a membrane having a pore size of 5 to 35 MWCO.

The glycerides may also be vegetable oils or animal fats.

In addition, the ratio of the glyceride and C ₁ to C ₅ alcohol in the reactor at the start of the reaction is preferably 1: 0.1 to 1.5 molar ratio.

In addition, the lipase may be Candida antarctica B lipase.

In addition, the membrane of the membrane module is preferably hydrophilic.

In addition, the membrane of the membrane module is preferably regenerated cellulose.

In addition, the C ₁ to C ₅ alcohol may be supplied additionally 1 to 5 times after the start of the reaction, but before the end of the reaction.

In addition, the reactor may further include a water jacket.

In addition, the reactor may be further provided with a mixing device.

In addition, the C ₁ to C ₅ alcohol may be methanol.

Biodiesel production method of the present invention can reduce the inhibition of the enzyme activity by the glycerol by continuously removing the glycerol using a membrane. In addition, by supplying the alcohol, one of the substrates of the transesterification reaction producing biodiesel, to the reaction mixture at a controlled rate, it is possible to prevent inactivation of the enzyme by the alcohol, thereby improving the conversion rate and the conversion rate. Furthermore, there is an advantage that the productivity of the biodiesel is significantly improved by continuously supplying the reactant and discharging the product.

1 is a transesterification reaction of triglycerides with alcohol.
2 is a conceptual diagram of glycerol removal.
3 is a conceptual diagram showing separation of glycerol by regenerated cellulose membrane.
4 is a conceptual diagram of a batch membrane bioreactor system.
5 is a conceptual diagram of a continuous membrane bioreactor system.
6 is a graph showing the effect of glycerol during biodiesel production.
Figure 7 is a photograph showing a drop image of glycerol in soybean oil / FAME / glycerol / methanol mixture.
8 is a graph (a) showing glycerol and FAME concentrations on the hydrophilic side, and a graph (b) showing methanol concentrations on the hydrophobic side.
9 is a graph showing the change in glycerol concentration at different flow rates.
10 is a graph showing the change in conversion and glycerol concentration with or without membrane module.
11 is a graph showing the change in conversion rate and the change in glycerol concentration according to the change in pore size.
12 is a graph showing the change in conversion rate in a continuous membrane bioreactor system.

Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description, numerous specific details, such as specific elements, are set forth in order to provide a thorough understanding of the present invention, and it is to be understood that the present invention may be practiced without these specific details, It will be obvious to those who have knowledge of. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Biodiesel production apparatus of the present invention

A reactor for producing biodiesel and glycerol by reacting glycerides and C ₁ to C ₅ alcohols with an immobilized lipase; And

The reaction mixture flowed out from the reactor is introduced into one area divided into membranes and moved in parallel with the membrane, and then flowed out. Separately, C ₁ to C ₅ alcohol is introduced into the other region separated by the membrane and Membrane module to membrane separator that flows out after moving in parallel

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A portion of the glycerol in the reaction mixture is characterized in that the permeation of the C ₁ to C ₅ alcohol flows in the region divided by the membrane.

As described above, the biggest problem of biodiesel production using enzymes is that glycerol produced with biodiesel inhibits the enzyme which is a catalyst. Therefore, there is a great demand for the removal of such glycerol, the present invention is characterized by removing the glycerol using a membrane bioreactor.

In the present invention, the transesterification reaction mixture and the alcohol phase are separated by a flat sheet-shaped regenerated cellulose membrane, and the produced glycerol is continuously removed through the membrane so that inhibition of the enzyme can be reduced.

Furthermore, the present invention is characterized in that a portion of the C ₁ to C ₅ alcohol is permeated into the region in which the reaction mixture flows among the regions separated by the membrane. This allows the alcohol to inactivate the enzyme to be supplied to the reaction mixture at a controlled rate using a hydrophilic membrane to prevent inactivation of the enzyme to prevent inhibition of the conversion rate. Furthermore, the present invention is also capable of improving the productivity of biodiesel for a short working time.

Such membranes may have the form of sheets mounted on flat plate-frame modules, or the form of tubes mounted on tube-frame modules, the structure of which may also be symmetrical or asymmetrical.

Lipase in the present invention acts as a catalyst to transesterify fats or oils with C ₁ to C ₅ alcohols to produce biodiesel and glycerol.

In addition, the reactor of the present invention may be a batch or a semi-batch, it is more preferable that the glyceride or glyceride and C ₁ to C ₅ alcohol is continuously introduced and the reaction mixture is continuously discharged.

Membrane bioreactors have several advantages over other reactor systems, of which the continuous process is possible. This continuous process is capable of using the most expensive enzymes as much as possible has the effect of improving productivity and economic efficiency.

Instead, membrane reactors suffer from performance degradation during operation, which is due to pore fouling during the filtration process. Occlusion refers to the deterioration of the filtration properties of the membrane as a result of the accumulation or adsorption of particles on or inside the pores.

In the present invention, the membrane bioreactor is characterized in that the lipid (hydrophobic) phase passes in one direction of the membrane and the aqueous phase passes in the other direction to minimize pore blockage of the membrane.

In other words, the direction in which the reaction mixture flows in the membrane separator and the direction in which the C ₁ to C ₅ alcohols flow in the opposite direction promotes permeation of glycerol and C ₁ to C ₅ alcohols and minimizes pore blockage. .

Wherein the membrane of the membrane module preferably has a pore size of 5 to 35 MWCO (molecular weight cut-off), if the pore size is less than 5 MWCO mass transfer is not easy, the added pressure is large, the operating cost is increased, There is a problem that pore blockage occurs much more easily. On the contrary, when the pore size exceeds 35 MWCO, C ₁ to C ₅ alcohols are excessively introduced into the reaction mixture to inactivate the enzymes early, and later in the reaction, glycerol is easily permeated in the reverse direction, making it difficult to express the function as a membrane.

The glyceride of the present invention is not limited as long as it is a substance capable of producing biodiesel as a result of the reaction, but is particularly preferably vegetable oil or animal fat in view of reproducibility and delocalization of resources.

In the reactor, the ratio of the glyceride and the C ₁ to C ₅ alcohol at the start of the reaction is preferably 1: 0.1 to 1.5 molar ratio. When the molar ratio of the alcohol is less than 0.1, the contact chance with glyceride is reduced. If the speed is too slow, on the contrary, if it exceeds 1.5 molar ratio, there is a problem that inactivation of enzyme occurs due to insoluble alcohol.

The lipase of the present invention is not limited as long as it is an enzyme capable of producing biodiesel as a result of catalyzing the reaction, and particularly, Candida antarctica B lipase has high efficiency.

In the present invention, the membrane of the membrane module is particularly preferably regenerated cellulose, and preferably hydrophilic in terms of permeation of glycerol and alcohol.

On the other hand, the reactor of the present invention may be a batch or a continuous, it is also possible that the C ₁ to C ₅ alcohol is a semi-batch is fed 1 to 5 additional times before the end of the reaction after the start of the reaction. The reason why the alcohol is divided and supplied is to suppress this effect because a high concentration of alcohol inactivates the enzyme.

The reactor constituting the biodiesel production apparatus of the present invention preferably further comprises a water jacket for temperature control, and may further include a mixing device such as an impeller for smooth mixing of the reactants. .

In the present invention, the C ₁ to C ₅ alcohol is particularly preferably methanol.

Hereinafter, embodiments of the present invention will be described.

Example

Test Example 1: Effect of Glycerol

Methanol (Sigma, USA), glycerol (Sigma, USA), and soybean oil (Ottogi, Korea) were each maintained at 50 ° C. for 12 hours. 20 g of soybean oil and glycerol (0, 0.5 g, 1 g, 2 g) were then stirred with 0.6 g of Novozym® 435 (Candyda antarctica lipase immobilized on a large pore acrylic resin, Novozymes, Denmark) at 50 ° C for 1 hour. . The transesterification reaction was initiated by adding 0.76 g of methanol.

The concentrations of FAME, glycerol and methanol were analyzed by Varian 450 gas chromatography equipped with a flame ionization detector (FID) and an HP-5 capillary column (25 m × 0.32 mm × 0.17 μm).

Analysis of FAME: Oven temperature was maintained at 50 ° C. for 1 minute, heated to 210 ° C. at a rate of 20 ° C./min, followed by 10 minutes. The temperature of the injector and detector was set at 250 ° C and 270 ° C, respectively. Methyl heptadecanoate (99.7%, Fluka) was used as internal standard and methyl linoleate (minimum 99%, Sigma) was used as standard.

Analysis of Glycerol: Oven temperature was maintained at 40 ° C. for 3 minutes, heated to 120 ° C. at a rate of 15 ° C./min, heated to 180 ° C. at a rate of 30 ° C./min, followed by 7 minutes. The temperature of the injector and detector was set at 250 ° C and 350 ° C, respectively. N, O-bis (trimethylsilyl) trifluoroacetamide containing trimethylchlorosilane (1%, Sigma) was used as the silylation reagent and 10 mM 1,2,4-butanetriol (99.0% Fluka) was used as an internal standard solution with pyridine (99.95%, JTBaker).

Analysis of Methanol: The oven temperature was maintained at 30 ° C. for 2 minutes, heated to 320 ° C. at a rate of 25 ° C./min, followed by 5 minutes. The temperature of the injector and detector was set at 250 ° C and 350 ° C, respectively. 10 mM n-hexane (Merck) was used as the internal standard solution with n-heptane.

6 is a graph showing the effect of glycerol during biodiesel production. The reaction was terminated after 1 hour with glycerol depleted in the initial mixture. However, biodiesel production was inhibited by glycerol and conversion and final conversion decreased with increasing amount of glycerol.

Test Example 2 Removal of Glycerol by Membrane

Removal of glycerol was performed at 50 ° C. with 70 g of soybean oil, 3 g of glycerol, and 30 g of FAME (FIG. 2). And 100 ml of methanol were separately maintained at 50 ° C. for 12 hours. The hydrophobic side consisted of a soybean oil / glycerol / biodiesel mixture and the hydrophilic side was methanol. Each phase was separated into a regenerated cellulose (RC) membrane (10 k MWCO SnakeSkin® Pleated Dialysis Tubing, Pierce, USA) as shown in FIG. The flow rate of each phase was 10 ml / min and was circulated in the opposite direction.

Membrane modules were applied to the biodiesel production process to remove glycerol, which affected the conversion rate and reaction rate. Glycerol was removed from the soybean oil / glycerol / biodiesel mixture (70 g / 30 g / 3 g) by a 10 k regenerated cellulose membrane as in FIG. The soybean oil / glycerol / biodiesel mixture was fed to the hydrophobic side where 100 ml of methanol was fed to the opposite side of the membrane.

Glycerol droplet images are shown in FIG. 7. The right side of Fig. 7 shows a rectangle on the left side.

On the hydrophilic side, glycerol and FAME concentrations were observed when the flow rate was 10 ml / min (FIG. 8 (a)) and the concentration of methanol was also observed on the hydrophobic side (FIG. 8 (b)). In the experiment, about 55% of glycerol was removed onto methanol on the hydrophobic side. At this time, leakage of FAME from the hydrophobic phase was negligible, and methanol permeation from the hydrophilic phase to the hydrophobic phase was also confirmed. And, even if the flow rate was changed to 10, 20 and 30 ml / min, there was no difference in the glycerol removal rate (Fig. 9).

Example 1 Production of Biodiesel Using a Batch Membrane Bioreactor (1)

The reactor consisted of two units, one for the reaction unit for transesterification and the other for the glycerol removal unit using the membrane module. The reaction temperature was maintained by a water jacket.

The reaction was carried out at 50 ° C. with 100 g soybean oil and Novozym® 435 (3% w / w soybean oil). 4 shows a batch system using a membrane module. Methanol and soybean oil were each maintained at 50 ° C. for 12 hours. The reaction was initiated by adding 3.77 g of methanol. The flow rates of the two phases were controlled with a Masterflex® L / S peristaltic pump (peristatic pump, Cole Parmer Instrument Company, USA) and a regenerated cellulose membrane (10 k MWCO SnakeSkin® Pleated Dialysis Tubing, Pierce, USA; 50 k and 25 k MWCO Cellu Sep® H1 Tubular Membrane, MFPI, USA) was used.

Biodiesel was produced using a membrane bioreactor. 100 g of soybean oil was used, and methanol was initially added at 3.77 g, and then no further was added to prevent inhibition by methanol. The hydrophobic and hydrophilic phases were separated into 10 k MWCO (molecular weight cut-off) regenerated cellulose membranes with a flow rate of 10 ml / min for each phase. Biodiesel conversion (FIG. 10 (a)) and glycerol concentration (FIG. 10 (b)) continued to increase on the hydrophobic side and the hydrophilic side, respectively. Methanol was continuously fed from the hydrophilic phase to the hydrophobic phase through the membrane, with biodiesel conversion reaching 98.8% after 14 hours and conversion above 99.0% after 15 hours. In addition, glycerol was continuously removed so that the reaction rate was maintained while the reaction was in progress. Finally, 35% of glycerol was removed and the reaction rate was increased by about 39.6%.

Comparative Example: Production of biodiesel using a batch bioreactor without a membrane module

Biodiesel was produced using a general bioreactor without a membrane module. 100 g of soybean oil was used, and after the reaction start time, 4 hours, and 8 hours, 3.77 g of methanol was added, and the conversion was measured (Fig. 10 (a)). As a result of the experiment, the conversion rate increased rapidly after each methanol addition step, and the conversion was no longer confirmed.

Example 2 Production of Biodiesel Using a Batch Membrane Bioreactor (2)

The effect of pore size on glycerol removal and methanol feed rate was investigated. Membranes of different pore sizes, namely regenerated cellulose membranes of 10 k, 25 k and 50 k MWCO, were used for the transesterification reaction.

The final conversion was more than 99% for membranes of 10 k MWCO, but only 78.5% for membranes of 50 k MWCO. The conversion rate increased as the membrane pore size increased, but at the same time the final conversion rate of biodiesel decreased (FIG. 11 (a)). This seems to be because methanol is fed too quickly from the hydrophilic phase into the reaction mixture so that the enzyme is inactivated by methanol. The larger the pore size of the membrane, the greater the amount of methanol permeated into the transesterification reaction mixture in a shorter time, and the more glycerol also permeates faster to the hydrophilic side (Figure 11 (b)).

Example 3 Production of Biodiesel Using a Continuous Membrane Bioreactor

The reaction was carried out at 50 ° C. with a mixture of soybean oil and methanol (1 mol: 0.8 mol) and 4 g of Novozym ㄾ 435. 5 shows a continuous system using a membrane module. Methanol and soybean oil were each maintained at 50 ° C. for 12 hours. The reaction was initiated by adding Novozymoz 435. The mixture of soybean oil and methanol was fed to the reactor by a peristaltic pump (Watson Marlow 101U). The flow rates of the hydrophilic and hydrophobic phases were controlled by a Masterflex® L / S peristaltic pump (Cole Parmer Instrument Company, USA), and the two phases were separated by regenerated cellulose membrane (25 k MWCO).

12 shows the conversion of a continuous process using a 25 k MWCO film. After 24 hours the peak conversion was 95%.

In the above description of the preferred embodiment of the present invention, the present invention is not limited to the specific embodiments described above, those skilled in the art various modifications without departing from the gist of the present invention Of course it is possible. Accordingly, the scope of the present invention should not be construed as being limited to the above-described embodiments, but should be determined by equivalents to the appended claims, as well as the following claims.

Claims (10)

A reactor for producing biodiesel and glycerol by reacting glycerides and C ₁ to C ₅ alcohols with an immobilized lipase; And
The reaction mixture flowed out from the reactor is introduced into one area divided into membranes and moved in parallel with the membrane, and then flowed out. Separately, C ₁ to C ₅ alcohol is introduced into the other region separated by the membrane and Membrane module spilled after moving in parallel
Including,
A portion of the glycerol in the reaction mixture is a biodiesel production apparatus, characterized in that permeate to the region of the C ₁ to C ₅ alcohol flow in the membrane divided area. The method according to claim 1,
Part of the C ₁ to C ₅ alcohol is biodiesel production apparatus, characterized in that permeate to the region in which the reaction mixture liquid flows in the region divided by the membrane. The method according to claim 1,
The reactor is a biodiesel production apparatus, characterized in that the continuous glyceride or glyceride and C ₁ to C ₅ alcohol is continuously introduced and the reaction mixture is continuously discharged. The method according to claim 1,
Biodiesel production apparatus characterized in that the direction in which the reaction mixture flows in the membrane module and the direction in which the C ₁ to C ₅ alcohol flows in the opposite direction. The method according to claim 1,
The membrane module biodiesel production apparatus, characterized in that it comprises a membrane having a pore size of 5 to 35 MWCO. The method according to claim 1,
The glyceride is a biodiesel production apparatus, characterized in that the vegetable oil or animal fat. The method according to claim 1,
Biodiesel production apparatus, characterized in that the ratio of the glyceride and the C ₁ to C ₅ alcohol in the reactor at the beginning of the reaction is 1: 0.1 to 1.5 molar ratio. The method according to claim 1,
The lipase is Candida antarctica B Candida antarctica Bio-diesel production apparatus characterized in that the lipase. The method according to claim 1,
Biodiesel production apparatus, characterized in that the membrane of the membrane module is regenerated cellulose. The method according to claim 1,
The C ₁ to C ₅ alcohol is biodiesel production apparatus characterized in that the supply is further supplied 1 to 5 times after the start of the reaction before the end of the reaction.

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