JPWO2006016492A1 - Method for producing composition for biodiesel fuel and apparatus for producing biodiesel fuel - Google Patents

Abstract

  The present invention is a composition for biodiesel fuel capable of removing gums, phospholipids, and free fatty acids to the extent necessary and sufficient for an efficient transesterification reaction to be carried out at a low cost and in a simple process. An object is to provide a method for manufacturing a product. The present invention comprises a first step of adding an organic acid to a stock oil to solidify a gum or phospholipid contained in the stock oil, and a second step of removing the solidified gum or phospholipid from the stock oil. And a third step of performing a transesterification reaction using a feedstock oil from which a solidified substance has been removed, and a method for producing a biodiesel fuel composition.

Description

  TECHNICAL FIELD The present invention relates to a method for producing biodiesel fuel and a biodiesel fuel production apparatus using raw oil, particularly unrefined vegetable oil as a raw material.

  In recent years, biodiesel fuel, which is a fuel for diesel engines, made from plant-containing fats and oils has been put into practical use. Biodiesel fuel is, for example, obtained by methyl esterifying vegetable oil, is an oxygen-containing fuel that contains oxygen in its chemical structure, and emits no harmful exhaust gas such as black smoke because it contains almost no sulfur content. Few. In addition, because it is derived from plants, carbon dioxide emissions are counted as zero according to the regulations set forth in the Kyoto Protocol. For these reasons, it has attracted attention as an alternative fuel for light oil that has a low environmental load. In Europe and the United States, standards and legal systems have already been established, and more than 2.5 million tons of soybeans and rapeseed oil are produced and used annually. Even in Japan, biodiesel fuel produced from waste cooking oil is used in some local governments, etc., and standardization of bioethanol and biodiesel fuel has begun to be considered.

  It is known that the fatty acid alkyl ester, which is the main component of biodiesel fuel, can be obtained by transesterification of monoglyceride, diglyceride, and triglyceride, which are the main components of fats and oils, with alkyl alcohol. It is also widely known that a fatty acid alkyl ester can be obtained by a transesterification reaction between a free fatty acid and an alkyl alcohol (for example, see Non-Patent Document 1), and this reaction is used to convert biodiesel fuel oil from fats and oils. Techniques for manufacturing have also been studied (for example, see Patent Documents 1 to 4).

Various attempts have been made to improve the esterification efficiency of these fatty acid alkyls so as to improve the efficiency of esterification and prevent impurities from remaining as much as possible.
For example, when a large amount of gum, phospholipids, and free fatty acids are contained in the transesterification reaction, these not only act on the catalyst to reduce the reaction yield, but also form an emulsion during purification, which is difficult to handle. Therefore, the feedstock oil is used after being purified by a clay treatment or a reduced pressure steam distillation step before the transesterification reaction.

Further, particularly in the industrialization process, studies are being conducted on the catalyst used in the transesterification reaction. The transesterification reaction proceeds efficiently when an alkaline catalyst is used, but when a large amount of free fatty acid is contained, it reacts with an alkali metal to produce metallic soap, which inhibits the catalytic activity. It becomes difficult to separate the by-product from glycerin. In addition, since gums also have surface-active ability, the activity of the alkaline catalyst is hindered if a large amount of gum is contained. Therefore, an acid catalyst such as sulfuric acid or phosphoric acid, which is less active than an alkaline catalyst, is often used in the transesterification reaction of an unrefined oil containing a large amount of free fatty acids and gums. In addition, solid acid catalysts are often used, and sulfonic acid-based ion exchange resins and solid acid catalysts in which heteropolyacid is supported on silica gel or activated carbon are known.
JP-A-2002-167356 JP 2002-294277 A JP 2000-44984 A JP 2000-109883 A "Organic Chemistry Handbook", Gihodo Publishing (1988), p. 1407-1409

  However, the method of refining the raw material oil by the clay treatment or the reduced pressure steam distillation step requires considerable cost and labor. According to these steps, refined palm oil having a free fatty acid content of 0.01% and a water content of 0.1% can be obtained, but as a raw material for biodiesel fuel, the purity up to this point is not necessary, but rather. There is a demand for a more cost-effective and simple process purification method.

  Further, since the method using an acidic catalyst is a homogeneous reaction system in which the catalyst is present in a state of being dissolved in the reaction solution, it is difficult to separate and recover the catalyst from the produced solution after the reaction. is there. On the other hand, the solid acid catalyst has insufficient activity. There is also a method of esterifying with a solid acid catalyst and then performing an ester exchange reaction with an alkali catalyst, but it becomes complicated due to two catalyst systems with completely different properties, and it is necessary to constantly control the solid acid catalyst reaction by the amount of fatty acid. It lacks sex. Further, according to this method, if the amount of free fatty acid is 30% or more, investment in a complicated process plant and profitability can be achieved, but if it is 10% to 30% or less, it is rather excessive investment. I will end up.

  Therefore, the present invention is a biodiesel fuel comprising a low cost and simple process capable of removing gums, phospholipids and free fatty acids to the extent necessary and sufficient for efficient transesterification. An object of the present invention is to provide a method for producing a composition for use. According to such a method, it is possible to use an alkaline catalyst having sufficient activity for the transesterification reaction.

  The present inventors have conducted extensive studies in view of the above problems, by adding organic acids such as oxalic acid and citric acid to unrefined oil, by solidifying and removing gums and phospholipids It has been found that these impurities can be removed to a sufficient extent for biodiesel fuel production, and the transesterification reaction can be efficiently performed.

  Therefore, the method for producing a composition for biodiesel fuel according to the present invention includes a first step of adding an organic acid to a raw material oil to solidify gum or phospholipid contained in the raw material oil, and solidifying It includes a second step of removing gum or phospholipid from the feedstock oil, and a third step of performing a transesterification reaction using the feedstock oil from which the solidified substance has been removed.

  In the present invention, the “gumminess” refers to the components of unrefined oil containing phospholipids, proteins and the like. By solidifying gums or phospholipids, they can be separated and removed from the solution phase easily and at low cost. Compared with the clay treatment and the reduced pressure steam distillation treatment, the removal rate is low, but sufficient purity can be obtained as a raw material of biodiesel fuel, and the transesterification reaction can be efficiently performed.

  Gum and phospholipids solidified with an organic acid are preferably removed by centrifugation. According to the centrifugal separation operation, the solid matter can be efficiently separated and removed from the liquid phase by utilizing the difference in specific gravities, and the excess water is also removed from the feed oil. Since the transesterification reaction performed after the second step is an equilibrium reaction, it is possible to move the equilibrium to the production system and increase the yield by removing water produced as a by-product. By removing water, salts contained therein can also be removed at the same time.

  The production method according to the present invention preferably further includes a step of heating the feedstock oil under reduced pressure after the second step and prior to the third step. For example, the pressure is less than 10 mmHg, preferably less than 5 mmHg, more preferably less than 1 mmHg, and the temperature is 80° C. or higher and 170° C. or lower, preferably 120° C. or higher and 160° C. or lower, and more preferably 140° C. or higher and 150° C. or lower. By heating under reduced pressure, organic fatty acids, water, odorous substances, etc. can be distilled off from the raw material oil.

  In the production method according to the present invention, free fatty acids, gums, and phospholipids can be removed sufficiently as described above, so it is preferable to use an alkaline catalyst having a high catalytic ability in the transesterification step. As the alkaline catalyst, for example, sodium hydroxide, potassium hydroxide, sodium methylate, potassium methylate, calcium hydroxide and the like can be used, but the alkaline catalyst is not limited thereto.

  Further, the production method according to the present invention preferably further includes a step of separating and removing the heavy liquid after the third step. Heavy liquid is a by-product of the transesterification process, which contains mainly glycerin. The heavy liquid can be separated by stationary separation, but can be separated more efficiently by centrifugation.

  The stock oil from which the heavy liquid has been removed, that is, the light liquid, is preferably refined by various methods thereafter. Examples of such a purification method include a method of treating with clay (desaponification product), centrifugation (deglycerin/desolidified product), heat treatment under reduced pressure (dehydration, demethanol), and the like. By these steps, the light liquid can be made into a fatty acid alkyl ester having a higher purity and a high-quality biodiesel fuel composition can be obtained.

  As the starting material of the above-mentioned production method, for example, it is preferable to use unrefined vegetable oils such as rapeseed oil, soybean oil, sunflower oil, and palm oil, and among them, crude palm oil (unrefined palm oil) that has the lowest production cost. ) Is preferred. Crude palm oil refers to palm oil from which gums, phospholipids and free fatty acids have not been removed.

  The present invention further provides a biodiesel production apparatus that includes an acid treatment unit, a centrifugal separation unit, and a transesterification reaction unit, and the acid treatment unit and the centrifugal separation unit are continuously connected. The acid treatment section is provided with a means for adding an organic acid to the raw material, a stirring means, and preferably a heating means. Since the acid treatment section and the centrifugal separation section are continuously connected, the solid content generated by the acid treatment can be separated by the centrifugal separation section. The centrifuge unit preferably comprises means for removing water containing solids, salts and the like after separation, and a unit conventionally used as a biodiesel production apparatus may be used. The transesterification reaction part is not particularly limited as long as the transesterification reaction is carried out, and a transesterification reaction device which has been used as a transesterification reaction device in conventional biodiesel fuel production may be used.

  It is also preferable that the biodiesel fuel production apparatus is further provided with a reduced pressure heating unit, and the acid treatment unit, the centrifugal separation unit, the reduced pressure heating unit, and the transesterification unit are successively connected in this order. With such a configuration, it is possible to further remove free fatty acids, water, and odorous substances from the raw oil from which the gum substance and phospholipid have been removed by acid treatment and centrifugation by reduced pressure heat treatment, so that the subsequent transesterification reaction In addition, it is possible to use a feedstock oil having less impurities.

  In addition to these, the biodiesel fuel production apparatus according to the present invention may include a stationary separation unit, a clay treatment unit, and a reduced pressure heat treatment unit.

  According to the method for producing a biodiesel fuel composition according to the present invention, prior to the transesterification reaction, the organic substance is added to solidify and separate the gum and phospholipid to separate and remove them, thereby efficiently transesterifying. The feedstock can be refined to the extent necessary and sufficient for the reaction to occur. According to this method, it is possible to produce a sufficiently high-quality composition for biodiesel fuel with a low cost and a simple process without increasing the purity more than necessary and without excessive investment.

  Further, according to the biodiesel fuel production apparatus of the present invention, the steps required for carrying out the production method of the present invention can be continuously performed, and the productivity can be improved.

  Incidentally, the biodiesel fuel production apparatus according to the present invention can also be provided with a crude glycerin refining unit for purifying the heavy liquid separated and removed from the light liquid after the transesterification reaction, whereby as a by-product. It is also possible to obtain glycerin of high purity.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic diagram of a process for producing a composition for biodiesel fuel according to the present invention, which uses the biodiesel fuel production apparatus according to the present invention. In this embodiment, crude palm oil is used as the raw material oil. Crude palm oil contains about 0.2% impurities such as gums and phospholipids and about 5% free fatty acids.

  First, an acid treatment step 10 is performed in the acid treatment section. In the acid treatment step 10, an organic acid is added to the raw material oil to condense gum and phospholipid to solidify. The organic acid is not particularly limited as long as it solidifies gum and phospholipids, for example, formic acid, acetic acid, propionic acid, phosphoric acid, butyric acid, lactic acid, malic acid, tartaric acid, citric acid, sorbic acid, fumaric acid, Benzoic acid, oxaloacetic acid, formic acid, valeric acid, glutamic acid, salicylic acid, oxalic acid, stearic acid, trifluoroacetic acid, picric acid, pantothenic acid, acrylic acid, etc. can be used, but in terms of cost and ease of handling, Phosphoric acid, oxalic acid or citric acid are particularly preferred. When oxalic acid is used, for example, it is added so as to be about 0.5% by weight at room temperature and stirred for about 1 hour, whereby a brown solid substance precipitates and floats or precipitates. After depositing the solid matter, it is preferable to heat to, for example, 90 to 100° C. for the subsequent centrifugal separation treatment.

  Next, the centrifugation step 12 is performed in the centrifugation section. In the centrifugation step 12, the solid substance of palm oil added with the organic acid is removed by centrifugation. The conditions for centrifugation can be easily selected and determined by those skilled in the art, and by this step, it is possible to remove water above the saturated water content. By removing the water here, the equilibrium of the transesterification reaction in which water is produced as a side reaction product is easily transferred to the production system. In this step, salts dissolved in the water can be removed together with the water.

  Then, the reduced pressure heating process 14 is performed. The reduced pressure heat treatment is performed in the reduced pressure heating unit. In the depressurization heating section, the feedstock oil is passed through a shell-and-tube heat exchanger, heated to the temperature required for depressurization treatment, and introduced into a vacuum deoxidizer. At the time of introduction, it is preferable to employ a method in which the feedstock oil is dispersed and introduced in a mist state, or is introduced in a spiral state so that the gas-liquid interface becomes large. The reduced pressure heating unit sets the pressure to less than 10 mmHg, preferably less than 5 mmHg, more preferably less than 1 mmHg, and the temperature to 80°C or higher and 170°C or lower, preferably 120°C or higher and 160°C or lower, and more preferably 140°C or higher and 150°C or lower. Is preferably possible. Further dehydration, deodorization, and deoxidation occur while the feedstock passes through the vacuum deoxidation tower.

  In addition, palm oil undergoes hydrolytic degradation under the influence of the lipase enzyme contained in the tuft. Free fatty acids produced by hydrolysis of vegetable oils and fats have mostly 6 to 22 carbon atoms, and under reduced pressure of less than 1 mmHg, they are completely vaporized at 150°C or lower, or have an appropriate vapor pressure. Therefore, it can be suitably removed by this step.

  In the steps so far, palm oil is usually refined to a free fatty acid content of about 0.5%, a water content of about 0.3%, and an odor substance content of about 0.01% or less. Conventional methods that used treatments such as clay treatment and vacuum steam distillation can achieve high purity with free fatty acids of about 0.01% and water of about 0.1%, but for the purpose of efficient transesterification reaction. The purity up to this point is not required, and the degree obtained by the method according to the present invention is sufficient.

  Subsequently, the transesterification reaction step 16 is performed in the transesterification reaction section using the purified palm oil. According to the production method of the present invention, since the free fatty acid is removed to an appropriate value in the reduced pressure heating section, the reaction can be suitably performed without inhibiting the activity of the alkaline catalyst. Specifically, the alkaline catalyst and the alcohol used for the transesterification reaction are mixed in advance, and this is mixed with palm oil. The reaction with an alkali catalyst can be carried out, for example, by the method disclosed in JP-A-10-245586 or a method analogous thereto. The reaction liquid after completion of the reaction is sent to a stationary/centrifugal separation unit.

  The stationary/centrifugal separation step 18 performed in the stationary/centrifugal separation section is separated into a light liquid mainly containing fatty acid methyl ester produced by the transesterification reaction and a heavy liquid mainly containing glycerin. It may be separated only by standing, or may be separated by using centrifugation.

  Next, in the clay treatment step 20, the light liquid is passed through a column filled with an adsorbent to remove alkaline impurities such as soap substances. As the filler, activated clay which is generally used for treating fats and oils is suitable. The clay treatment step 20 is performed in the clay treatment section of the biodiesel fuel production apparatus according to the present invention.

  In the subsequent centrifuge step 22, a centrifuge treatment is performed to remove the fine powder of the filler. At this time, a small amount of glycerin remaining can be removed. The centrifugation step 22 is performed in the centrifugation section.

  In the reduced pressure heat treatment step 24 performed in the reduced pressure heating section, low boiling point substances such as water and methanol are removed as final purification to obtain palm biodiesel oil.

  The heavy liquid containing glycerin as a main component obtained in the stationary/centrifuging step 18 can be subjected to a neutralization treatment step 32 and a distillation step 34 to obtain glycerin having a purity of 99% or more.

  As described above, the biodiesel fuel production apparatus according to the present invention is suitable for continuously performing each process, and high productivity can be obtained.

  According to the production method of the present invention, a crude diesel oil having the properties shown in Table 1 was used as a raw material oil to produce a biodiesel fuel.

まず、この原料油に、酸処理として、シュウ酸（０．５重量％）を室温で加え、１時間攪拌したところ褐色の固形物が現れた。

First, oxalic acid (0.5% by weight) was added to this raw material oil as an acid treatment at room temperature and stirred for 1 hour, whereupon a brown solid substance appeared.

  Subsequently, as a centrifugal separation treatment, the raw material oil was heated to 95° C. by a heat exchanger, and this was applied to a centrifugal separator (centrifugal force 1000 G: flow rate 15 liters per minute) to remove solids.

  The raw material oil after solid matter removal was passed through a multi-tube heat exchanger to be heated to 145° C., and then the raw material oil was put into a vacuum deoxidizing tower. The absolute pressure of the vacuum tower was 0.8 mmHg, and the residence time was 15 minutes. This raw material oil was cooled to 65° C. by a heat exchanger and used in a transesterification reaction.

  Using potassium hydroxide as a catalyst, potassium hydroxide was previously dissolved at a ratio of 11 parts by weight to 100 parts by weight of methyl alcohol (purity: 99.5%), and the obtained solution was mixed with a feed oil. Let react for minutes.

  The product obtained after the reaction was passed through a centrifugal separator (centrifugal force 1000 G: flow rate 15 liters per minute) to separate into a fatty acid methyl ester layer (light liquid) and a glycerin layer (heavy liquid).

  The fatty acid methyl ester layer was passed through a column packed with activated clay (1 part by weight to 100 parts by weight of fatty acid methyl ester) at a flow rate of 15 liters/minute. The fatty acid methyl ester layer after passing was again subjected to a centrifuge (centrifugal force 1000 G: 15 liter/min) to separate solids. This was heated to 65 to 75° C. and subjected to reduced pressure heat treatment with an absolute pressure of 100 mmHg and a residence time of 20 minutes. The obtained substance was sampled and the property was analyzed.

The property analysis of the fatty acid methyl ester was carried out by a method defined in JIS standard or a usual method other than the component analysis by gas chromatography. The conversion rate in Table 1 shows the yield of fatty acid methyl ester with respect to the fatty acid glyceride in the feed oil, and in fact,
(Conversion rate)=(amount of fatty acid methyl ester)/(amount of raw material oil used in the reaction)
Is defined by The odorous substance concentration was determined from the peak area below the retention time of fatty acid methyl esters other than alcohol in a gas chromatograph.

Comparative example

  It was manufactured using the same manufacturing apparatus as in Example 1 described above. However, the treatment of adding oxalic acid was not performed. The results of property analysis are shown in Table 2.

It is explanatory drawing which shows the outline of the manufacturing process of the composition for biodiesel fuels which concerns on this invention.

Claims (10)

A first step of adding an organic acid to a raw material oil to solidify a gum or phospholipid contained in the raw material oil;
A second step of removing the solidified gum or phospholipid from the feedstock;
A third step of performing a transesterification reaction using the feedstock oil from which the solidified substance has been removed, the method for producing a biodiesel fuel composition.   The method according to claim 1, wherein the organic acid is selected from the group consisting of phosphoric acid, oxalic acid and citric acid.   The production method according to claim 1 or 2, wherein in the second step, the solidified gum or phospholipid is removed by centrifugation.   The manufacturing method according to claim 1, further comprising a step of heating the feedstock oil under reduced pressure after the second step and before the third step.   The manufacturing method according to any one of claims 1 to 4, wherein the third step is performed in the presence of an alkaline catalyst.   The manufacturing method according to any one of claims 1 to 5, further comprising a step of removing heavy liquid after the third step.   The manufacturing method according to claim 6, further comprising at least one of a clay treatment step, a centrifugation treatment step, and a heating step under reduced pressure after the step of removing the heavy liquid.   The manufacturing method according to claim 1, wherein the raw material oil is crude palm oil.   A biodiesel fuel production apparatus comprising at least an acid treatment unit, a centrifugal separation unit, and a transesterification unit, wherein the acid treatment unit and the centrifugal separation unit are continuously connected.   The reduced pressure heating unit is provided between the centrifugal separation unit and the transesterification unit, and the acid treatment unit, the centrifugal separation unit, the reduced pressure heating unit, and the transesterification unit are sequentially and continuously connected to each other. Biodiesel fuel production equipment.

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