KR20120054973A - Method of extracting lipids from microalgae by two step pyrolysis - Google Patents

Abstract

PURPOSE: A collecting method of lipids from microalgae is provided to effectively collect lipids among various components in microalgae by simple processes, and to manufacture a part of pure hydrocarbon consisting of only carbon and hydrogen by decomposing lipids during thermal decomposition. CONSTITUTION: A collecting method of lipids from microalgae comprises a step of primary thermal-decomposing microalgae biomass at 250-400 °C; a step of removing saccharides and proteins from the microalgae biomass; and a step of obtaining primary decomposed product; a step of secondary decomposing the primary decomposed product and collecting only lipids, which are able to be converted to fuel easily.

Description

Method of extracting lipids from microalgae by two step pyrolysis}

The present invention relates to a method for recovering lipids as a raw material for producing transport fuel from microalgal biomass, and more particularly, to remove sugars and proteins that are difficult to convert from microalgal biomass to fuel. It relates to a two-stage pyrolysis method for recovering only lipids by first pyrolyzing at a temperature of from 400 ° C., and removing the sugars or proteins, and further thermally decomposing the first pyrolysis product at a temperature of 450 to 700 ° C.

Concerns about global warming and fossil fuels are driving the production of fuels using biomass. On the other hand, biofuel production using grain-based resources is a growing concern due to environmental burdens and competition with food resources. Therefore, a bioenergy production method using microalgae or forest resources without competition with food is attracting attention. Among them, microalgae have better photosynthesis efficiency than land plants, can directly use carbon dioxide emitted from thermal power plants, and a large part of the body is composed of lipids that can be converted into fuel.

Part of the components of the microalgal biomass that can be easily converted into fuel can be converted into fuel for transportation by a transesterification method or a deoxygenation method as lipids. Representative components other than lipids, sugars or proteins can also be converted to energy, but there is a problem that requires a complicated process.

Therefore, a number of methods for effectively extracting only lipids from microalgae have been proposed in bioenergy production using microalgae. A conventionally used method is to extract lipids in microalgae using a nonpolar organic solvent such as hexane. However, this technique has a problem in that the extraction efficiency is extremely low in the case of microalgae used in an excessive amount of organic solvent and surrounded by a rigid cell wall. In order to solve this problem, various techniques for breaking down microalgal cell walls have been proposed.

In addition, a lipid extraction method using supercritical water or supercritical carbon dioxide has also been proposed, but has been pointed out that the process conditions are severe. In addition, various methods for extracting lipids from microalgae have been proposed.

On the other hand, pyrolysis technology has been widely used for high quality of lower resources, and a method of producing liquid fuel by applying pyrolysis technology to woody biomass resources has recently been announced. However, the products produced through the pyrolysis technology occupy a large number of polar organic compounds, which requires a separate high quality or reforming process to be used as a fuel. In addition, there is a high risk of causing corrosion in the apparatus used because of the high organic acid content in the product.

In order to solve the above problems of the prior art, the present invention devised a method of effectively recovering lipids without using an organic solvent and without breaking down algal cells.

In order to achieve the above object, the present invention is characterized by recovering microalgal lipids using pyrolysis.

In addition, the present invention is focused on the fact that the decomposition temperature of sugars and proteins in the microalgal constituents is lower than the volatilization temperature of lipids, it is characterized by the efficient recovery of lipids from microalgae by using a two-stage pyrolysis method.

According to the present invention, there is an advantage of effectively recovering lipids among various components in the microalgae with a simple process configuration. In addition, during the pyrolysis process, the lipids are decomposed to produce some pure hydrocarbons composed exclusively of carbon and hydrogen, thereby providing an additional effect of reducing the load of the subsequent lipid conversion process.

1 is a schematic diagram showing a two-stage pyrolysis method for extracting lipids from microalgal biomass according to the present invention,
2 is Chlorella sp. A graph showing the pyrolysis characteristics of KR-1 microalgae,
3 is Chlorella sp. Produced in a two-step pyrolysis process. This is a graph comparing the boiling point distribution of KR-1 microalgae pyrolysis oil with that of soybean oil.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, microalgae biomass is pyrolyzed in a first pyrolysis reactor. At this time, the temperature is suitable for 250 ℃ to 400 ℃, since the decomposition effect of sugar or protein is insignificant at a temperature below 250 ℃, since the decomposition of the lipid component occurs at a temperature above 400 ℃ because the disadvantage that the recovery rate is lowered to be.

In the first pyrolysis process, sugars and proteins are decomposed and released as organic acids, aldehydes, and furan compounds, which can be recovered and commercialized separately.

In the first pyrolysis, the first pyrolysis product from which sugars and proteins have been removed is fed to a second pyrolysis reactor to recover lipids. At this time, the temperature is suitable from 450 ℃ to 700 ℃, which does not volatilize the lipid at a temperature below 450 ℃, thermal decomposition of the lipid is excessively proceeded at temperatures above 700 ℃ is converted to char (char) and gas has a problem Because.

The pyrolysis residence time may vary depending on the composition of the desired product.If the residence time is shorter, the recovery of lipids is higher but is mainly released in the form of fatty acids or fatty acid esters. There is an advantage of reducing the load on the fuel conversion process.

The residence time is suitable for 30 seconds to 2 hours, preferably a treatment time of 2 minutes to 30 minutes.

The final residues remaining in the secondary pyrolysis reactor can be used as solid fuels or land modifiers. In addition, non-condensable gases produced during the second pyrolysis process can be burned and used to provide the energy needed for pyrolysis or algae biomass drying, minimizing additional energy costs for the process.

Hereinafter, the present invention will be described in detail with reference to Examples and Test Examples. However, these are intended to explain the present invention in more detail, and the scope of the present invention is not limited by the following examples and test examples.

[ Example  1] Microalgae Biomass  Pyrolysis Characterization

Chlorella sp. With a lipid content of 36.5%. The pyrolysis of KR-1 (KCTC 0426BP) biomass was carried out using a thermogravimetric analyzer at a rate of 5 ° C./minute in a nitrogen atmosphere. As shown in FIG. 2, the microalgal biomass undergoes two stages of pyrolysis, wherein sugars or proteins are decomposed at 280 ° C., and lipids are decomposed at 400 ° C. Therefore, it can be seen that saccharides, proteins and lipids can be separated through a two-step pyrolysis process.

[ Example  2] Microalgae Biomass  Rapid pyrolysis

The biomass of Example 1 was rapidly pyrolyzed at 400, 500 and 600 ° C. and the resulting oil was analyzed. Chlorella sp. In the case of KR-1, fatty acids that make up lipids are mostly 16 and 18 carbon atoms, and pyrolysis recovery oil is mainly composed of 16 and 18 fatty acids. In addition, it can be seen that the carbonyl group of the fatty acid or fatty acid ester is removed through pyrolysis to generate a large amount of hydrocarbon having 15 and 17 carbon atoms.

Although lipids can be recovered only by single-stage microalgal biomass pyrolysis, analysis of the recovered lipids yielded a large number of by-products such as acetic acid and 2-methylfuran, and phase separation was observed due to the presence of polar compounds. This is because decomposition products of saccharides are mixed with lipids during pyrolysis.

[ Example  3] Microalgae Biomass  1st pyrolysis

Chlorella sp. 20 g of KR-1 biomass was pyrolyzed at 350 ° C. for 30 minutes in an oxygen-free atmosphere.

The pyrolysis conversion was 28.7% and the liquid recovery was 20.8%. The resulting liquid was brown in color and occupied a large number of polar organics. Gas chromatography / mass spectrometry (GC / MS) analysis of liquids obtained through primary pyrolysis showed that low-molecular-weight organic acids such as acetic acid and propanoic acid, and aldehydes and furfural such as acetaldehyde Furan compounds were produced, and no fatty acids or hydrocarbons were detected.

The heat treatment time was shortened to about 5 to 15 minutes, and the same results as in the case of 30 minutes were obtained.

Example 4 Secondary Pyrolysis of Microalgal Biomass Primary Pyrolysis Product

The primary pyrolysis product was obtained by removing sugars or proteins from the oil obtained through the first pyrolysis process according to Example 3. 10 g of the first pyrolysis product was pyrolyzed at 600 ° C. for 30 minutes in an oxygen-free atmosphere.

The pyrolysis conversion was 71.6% and the oil recovery was 50.9%. The resulting oil was a black liquid, and gas chromatographic / mass spectrometric analysis of the resulting oil resulted in a significant portion of 16 and 18 free fatty acids and 15 and 17 hydrocarbons. In addition, hydrocarbons and fatty acids having 7 or more carbon atoms were produced, and low molecular weight organic acids or furan compounds recovered during the first pyrolysis process were not detected.

The heat treatment time was shortened to about 5 to 15 minutes, and the same results as in the case of 30 minutes were obtained.

Referring to FIG. 3, which analyzes the distillation characteristics of lipids obtained through two-stage pyrolysis, it can be seen that the hardening effect can be obtained through the two-stage pyrolysis process, which shows a lower boiling range compared to soybean oil, which is a representative vegetable lipid.

Two-stage pyrolysis was able to finally recover 36.3% of lipids consisting of free fatty acids, pure hydrocarbons, etc. from the microalgal biomass.

[ Example  5] Microalgae Biomass  Secondary pyrolysis residue analysis

The second pyrolysis process according to Example 4 yielded lipids, and elemental analysis of the final residues was carried out. From the composition of the final residue, it can be seen that 57.05% of carbon and 1.68% of hydrogen can be used as a solid fuel and provide the heat required to dry the microalgae in Examples 3 and 4 above.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated that it can be changed.

Claims (5)

Lipid recovery from microalgae consisting of the following steps:
(1) first pyrolysing the microalgal biomass at 250 to 400 ° C .;
(2) removing the saccharides or proteins from the primary pyrolysis-treated microalgal biomass to obtain a primary pyrolysis product; And
(3) recovering only lipids by secondary pyrolysis of the primary pyrolysis product at 450 to 700 ° C .; The method of claim 1,
Wherein said first pyrolysis proceeds at 350 ° C. The method according to claim 1 or 2,
Wherein said secondary pyrolysis proceeds at 650 ° C. 4. The method according to any one of claims 1 to 3,
The lipid finally obtained from the recovery method is characterized in that it does not contain a low molecular weight organic acid or furan compound. A process for obtaining lipids by pyrolysis by the process according to any one of claims 1 to 3 and using the final residue remaining as a solid fuel.

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