Biofuel production method

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

Biofuel production method

[0001] The present invention relates to a method for producing biofuel.

[0002] In recent years, the world has been facing an energy crisis due to the depletion of fossil fuels and worsening environmental problems. Under these circumstances, biofuels derived from sustainable biomass resources have attracted attention as one of the means to diversify energy sources and reduce carbon emissions, and research and development into their widespread use is intensifying.

[0003] Examples of biofuels include bioethanol, which is produced by fermenting and distilling plants such as corn and sugarcane; fatty acid methyl esters (FAME) produced from fats and oils contained in vegetable oils and waste cooking oils, and biodiesel (BDF) containing hydrogenated vegetable oil (HVO); and sustainable aviation fuel (SAF), which is obtained by adjusting the carbon number of hydrogenated vegetable oil (HVO).

[0004] Of these, biofuels made from corn, sugarcane, vegetable oil, etc., can be used for food, which poses a food competition problem. Therefore, attempts are being made to produce biofuels using non-edible biomass resources.

[0005] Palm oil is the most widely used vegetable oil in the world. Palm oil can be extracted from the fruit (fruit bunch) of the oil palm. Palm kernel oil can also be extracted from the kernel of the oil palm.

[0006] Palm oil is typically produced through processes such as steaming palm fruit, squeezing, filtering, and refining. The palm oil production process generates a large amount of waste. Palm oil mill effluent (POME) is a highly concentrated organic wastewater containing a large amount of solid organic matter and lipids, and its discharge volume is particularly large. In Indonesia and Malaysia, where palm oil mills are located, POME is treated in anaerobic lagoons without being effectively utilized. Since POME wastewater treatment requires a long hydraulic retention time (HRT), it is often left untreated for long periods of time, resulting in unpleasant odors due to fermentation gas, pest damage, and water pollution. Furthermore, the anaerobic decomposition of POME releases methane, a greenhouse gas, into the atmosphere.

[0007] Therefore, methods for effectively utilizing non-edible POME have been studied. For example, Patent Document 1 describes an invention relating to a two-stage method for producing biodiesel fuel using fatty acids from waste cooking oil, POME, or non-edible palm oil. Patent Document 1 also describes that fatty acid methyl esters (FAME) can be obtained by transesterification of fatty acids obtained from POME or the like with methanol using benzine as a catalyst.

[0008] JP 2022-45854 A

[0009] When attempting to produce biofuel containing fatty acid methyl esters (FAME) using palm oil mill effluent (POME), there have been cases where it has been impossible to obtain FAME in a high yield due to the influence of impurities contained in POME.

[0010] Furthermore, when attempting to produce FAME after removing impurities contained in POME, fatty acids and other raw materials for FAME are often removed along with the impurities, or FAME cannot be obtained in high yield even after the impurities are removed.

[0011] Therefore, the present invention provides a method for producing a biofuel containing fatty acid methyl esters (FAME) and from which impurities have been removed, using palm oil mill effluent (POME).

[0012] The present inventors have discovered that when obtaining FAME from POME, a methyl esterification reaction using an acid-alkali method can produce FAME in a high reaction yield regardless of the impurities contained in the POME, and that the impurities can be suitably removed from the resulting reaction solution. This makes it possible to produce a biofuel containing FAME from which the impurities have been removed. That is, the present invention has, for example, the following aspects.

[0013] [1] A method for producing a biofuel, comprising a methyl esterification step of reacting palm oil mill effluent (POME) with an acid catalyst and methanol, followed by a base catalyst and methanol to produce fatty acid methyl esters (FAME). [2] The method according to [1] above, further comprising a POME purification step, which includes an adsorption step of contacting POME with an adsorbent, before the methyl esterification step. [3] The method according to [1] above, further comprising a FAME purification step, which includes an adsorption step of contacting a product containing FAME with an adsorbent, after the methyl esterification step. [4] The method according to any one of [1] to [3] above, further comprising a hydrogenation step of hydrotreating the product containing FAME. [5] The method for producing a biofuel according to any one of [1] to [4] above, wherein the biofuel is a biodiesel fuel. [6] A method for removing impurities from palm oil mill effluent (POME), comprising a methyl esterification step of reacting POME with an acid catalyst and methanol, followed by a base catalyst and methanol to produce fatty acid methyl esters (FAME). [7] The method for removing impurities from POME according to [6] above, further comprising a POME purification step, prior to the methyl esterification step, comprising an adsorption step of contacting POME with an adsorbent. [8] The method for removing impurities from POME according to [6] above, further comprising a FAME purification step, following the methyl esterification step, comprising an adsorption step of contacting a product containing FAME with an adsorbent.

[0014] According to the present invention, there is provided a method for producing a biofuel containing fatty acid methyl esters (FAME) and from which impurities have been removed, using palm oil mill effluent (POME).

[0015] Hereinafter, embodiments of the present invention will be described in detail. In this specification, when an upper limit and a lower limit of a numerical range are given, the upper limit and the lower limit can be appropriately combined, and the resulting numerical range is also considered to be disclosed.

[0016] 1. Method for Producing Biofuel The method for producing biofuel according to the present invention includes a methyl esterification step in which palm oil mill effluent (POME) is reacted with an acid catalyst and methanol, and then with a base catalyst and methanol to produce fatty acid methyl esters (FAME).

[0017] <Methyl esterification step> The methyl esterification step is a step in which POME is reacted with an acid catalyst and methanol, and then with a base catalyst and methanol to produce FAME. The methyl esterification step is also called an acid-alkali method.

[0018] (Palm Oil Mill Effluent (POME)) Palm oil mill effluent (POME) is a waste liquid generated in the manufacturing process of palm oil and palm kernel oil. In this specification, "palm oil" means palm oil and / or palm kernel oil. In one embodiment, POME is a liquid containing at least one of a first waste liquid generated in the cooking process of oil palm fruit (FFB), a second waste liquid generated in the purification process for filtering the fruit, a third waste liquid generated in the separation process of kernel oil (PK), and a fourth waste liquid generated in the mill cleaning, or a dried product thereof. In one embodiment, POME is preferably a liquid containing the first waste liquid and the third waste liquid, or a dried product thereof. In another embodiment, POME is preferably a liquid containing the second waste liquid, or a dried product thereof. In another embodiment, POME is preferably a liquid containing the first waste liquid, the second waste liquid, and the third waste liquid, or a dried product thereof.

[0019] POME may be liquid or dried, but is preferably dried from the viewpoint of transportation costs, reaction efficiency, etc. In this specification, "dried product" includes dehydrated cake. Dried POME can be produced by dehydrating a raw POME solution. Examples of dehydration methods include sun drying, dehydration using a dehydration aid and / or a polymer flocculant, and dehydration using a dehydrator (such as a multi-rotating disk press dehydrator). Two or more of these dehydration methods may be combined. For example, POME can be dehydrated using a dehydration aid and / or a polymer flocculant, and then dehydrated using a dehydrator (such as a multi-rotating disk press dehydrator). Dried POME typically has a moisture content of 20% by mass or less relative to the total mass of POME.

[0020] POME contains glycerides, fatty acids, and impurities, and may also contain fuel components such as palm kernel shells (PKS) and wood flour.

[0021] Glycerides are esters of glycerol and fatty acids. In this specification, the term "glyceride" refers to at least one of monoglycerides, diglycerides, and triglycerides. Glycerides include glycerol and C ８ ~C ２４ Saturated fatty acids and C １６ ~C ２４ It is preferred to include a glyceride which is an ester of at least one unsaturated fatty acid, and ８ ~C ２０ Saturated fatty acids and C １６ ~C ２０It is more preferable to contain a glyceride that is an ester of at least one unsaturated fatty acid, even more preferable to contain a glyceride that is an ester of glycerol and at least one selected from the group consisting of caprylic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, eicosanoic acid, behenic acid, oleic acid, linoleic acid, α-linolenic acid, and γ-linolenic acid, and from the viewpoint of obtaining a biofuel with a high cetane number, it is particularly preferable to contain a glyceride that is an ester of glycerol and at least one selected from the group consisting of palmitic acid, margaric acid, stearic acid, and eicosanoic acid. The above-mentioned glycerides may be contained alone or in combination of two or more.

[0022] The glyceride content is preferably 10% by mass or more and 95% by mass or less, and more preferably 10% by mass or more and 80% by mass or less, based on the total mass of the dried POME material.

[0023] The fatty acids include C ８ ~C ２４ Saturated fatty acids and C １６ ~C ２４ It is preferable that the fatty acid composition contains at least one unsaturated fatty acid. ８ ~C ２２ Saturated fatty acids and C １６ ~C ２０ It is more preferable to contain at least one unsaturated fatty acid, and even more preferable to contain at least one selected from the group consisting of caprylic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, eicosanoic acid, behenic acid, oleic acid, linoleic acid, α-linolenic acid, and γ-linolenic acid, and from the viewpoint of obtaining a biofuel with a high cetane number, it is particularly preferable to contain at least one selected from the group consisting of palmitic acid, margaric acid, stearic acid, and eicosanoic acid. The above-mentioned fatty acids may be contained alone or in combination of two or more.

[0024] The fatty acid content is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 40% by mass or more and 80% by mass or less, based on the total mass of the dried POME material.

[0025] Examples of impurities include alkali metals such as sodium (Na) and potassium (K), alkaline earth metals such as magnesium (Mg), calcium (Ca), and barium (Ba), semimetals or nonmetals such as boron (B), aluminum (Al), phosphorus (P), and sulfur (S), transition metals such as titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), and cadmium (Cd), and halogens such as chlorine (Cl). The above-mentioned impurities may be contained alone or in combination of two or more. In this specification, "alkaline earth metal" includes magnesium.

[0026] The content of impurities is preferably 0.05% by mass or less, and more preferably 0.005% by mass or less, based on the total mass of the dried POME.

[0027] The water content of the POME is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 0.1% by mass or more and 10% by mass or less, and particularly preferably 1% by mass or more and 5% by mass or less, based on the total mass of the POME.

[0028] The gross calorific value (HHV) of POME is preferably 3,000 kcal / kg or more, more preferably 4,000 kcal / kg or more, and even more preferably 4,000 kcal / kg or more and 30,000 kcal / kg or less.

[0029] (Reaction with Acid Catalyst and Methanol) In the methyl esterification step according to the present invention, POME is first reacted with an acid catalyst and methanol. By reacting POME with the acid catalyst and methanol, at least one of the following reactions occurs: methylation of fatty acids contained in POME, and methyl esterification (methanolysis) of triglycerides contained in POME by transesterification. This allows fatty acid methyl esters (FAME) to be obtained.

[0030] (1) Acid Catalyst The acid catalyst is not particularly limited, but examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; inorganic oxides such as tin oxide and zinc oxide; alcoholates such as titanium tetrapropoxide; and cation exchange resins. Among these, the acid catalyst preferably contains an inorganic acid, more preferably contains at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, and even more preferably contains sulfuric acid. The above-mentioned acid catalysts may be used alone or in combination of two or more.

[0031] The amount of acid catalyst used is preferably a substance amount ratio of 0.05 to 3, more preferably 0.1 to 2, and even more preferably 0.1 to 1.5, relative to the free fatty acids contained in POME. In this specification, "substance amount" means the amount of compound expressed in moles. Therefore, "substance amount ratio" can also be referred to as "molar ratio." In addition, the "substance amount of free fatty acids contained in POME" is measured by the method described in the Examples.

[0032] (2) Methanol The amount of methanol used is preferably from 1 to 60 in terms of the mass ratio relative to the free fatty acids contained in POME, more preferably from 3 to 50, even more preferably from 5 to 40, and particularly preferably from 10 to 30. In one embodiment, when no additional methanol is added in the reaction with a base catalyst and methanol described below, the amount of methanol used is preferably from 1 to 90 in terms of the mass ratio relative to the free fatty acids and triglycerides contained in POME, more preferably from 1.5 to 80, even more preferably from 10 to 70, and even more preferably from 15 to 70, 15 to 60, 15 to 50, 15 to 40, 15 to 30, 20 to 70, 20 to 60, 20 to 50, 20 to 40, 20 to 30, 30 to 70, 30 to 60, 30 to 50, and 30 to 40.

[0033] (3) Solvent The reaction with the acid catalyst and methanol may further use a solvent. The solvent is not particularly limited, but examples thereof include hydrocarbon solvents such as hexane; ether solvents such as diethyl ether, tetrahydrofuran (THF), and 1,4-dioxane; and halogenated solvents such as dichloromethane and chloroform. These solvents may be used alone or in combination of two or more.

[0034] The amount of the solvent used is preferably 1% by mass or more and 60% by mass or less, more preferably 3% by mass or more and 50% by mass or less, even more preferably 5% by mass or more and 40% by mass or less, and particularly preferably 10% by mass or more and 30% by mass or less, relative to the mass of POME.

[0035] (4) Reaction The reaction with the acid catalyst and methanol is carried out, for example, by mixing and stirring POME, the acid catalyst, methanol, and, if necessary, a solvent.

[0036] The reaction can be carried out either batchwise or continuously. The stirring method can be appropriately selected depending on the reaction treatment method, the type of reactor, etc., and any known stirring method can be applied.

[0037] Stirring is preferably carried out under heating, for example, at a temperature of 25° C. to 80° C., preferably 30° C. to 70° C., and more preferably 40° C. to 65° C. Stirring may also be carried out under pressure. Those skilled in the art can select a preferred temperature and pressure depending on the desired reaction time, etc.

[0038] The stirring time may be within a range in which the reaction between the acid catalyst and methanol proceeds sufficiently, and those skilled in the art can appropriately select the stirring time depending on the reaction treatment method, the type of reactor, etc. For example, in the case of a batchwise reaction, the stirring time can be appropriately selected from the range of about 30 to 90 minutes, preferably about 45 to 75 minutes.

[0039] (Reaction with a base catalyst and methanol) In the methyl esterification step according to the present invention, POME is reacted with an acid catalyst and methanol, and then with a base catalyst and methanol. By reacting POME with the base catalyst and methanol, methyl esterification (methanolysis) of triglycerides contained in POME proceeds through a transesterification reaction. This allows fatty acid methyl esters (FAME) to be obtained.

[0040] In the reaction with the acid catalyst and methanol described above, the methyl esterification of fatty acids proceeds rapidly. On the other hand, the reaction rate of methyl esterification by transesterification of triglycerides tends to be slow. Therefore, in the reaction with the acid catalyst and methanol, some triglycerides may remain unreacted. In contrast, in the reaction with the base catalyst and methanol, the methyl esterification of fatty acids does not proceed in principle, and only methyl esterification by transesterification occurs. In this case, the reaction rate of the transesterification reaction is fast. As a result, the unreacted triglycerides in the reaction with the acid catalyst and methanol can be converted to fatty acid methyl esters (FAME). In addition, fatty acid ethyl esters, fatty acid propyl esters, fatty acid isopropyl esters, fatty acid butyl esters, etc. can also be converted to fatty acid methyl esters (FAME).

[0041] (1) Base Catalyst The base catalyst is not particularly limited, but examples thereof include alkali metal catalysts, alkaline earth metal catalysts, and amine-based base ion exchange resins.

[0042] Examples of the alkali metal catalyst include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal hydrogencarbonates; alkali metals; and alkali metal oxides.

[0043] Examples of alkaline earth metal catalysts include alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide, and barium hydroxide; alkaline earth metal carbonates such as magnesium carbonate and calcium carbonate; alkaline earth metal hydrogencarbonates; alkaline earth metals; and alkaline earth metal oxides.

[0044] Among the above, the base catalyst preferably contains an alkali metal catalyst, preferably an alkali metal hydroxide, more preferably at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide, even more preferably at least one selected from the group consisting of sodium hydroxide and potassium hydroxide, and particularly preferably potassium hydroxide. The above-mentioned base catalysts may be used alone or in combination of two or more.

[0045] The amount of base catalyst used is preferably 0.01 to 3 in terms of the molar ratio relative to the triglycerides contained in POME, more preferably 0.05 to 2 in terms of the molar ratio, and even more preferably 0.1 to 1 in terms of the molar ratio. Since the reaction with the base catalyst and methanol is carried out after the reaction with the acid catalyst and methanol, the base catalyst is added in an amount that satisfies the neutralization equivalent of the acid catalyst and the molar ratio relative to the triglycerides contained in POME in the above-mentioned range. In this specification, the "molar amount of triglycerides contained in POME" is measured by the method described in the Examples.

[0046] (2) Reaction The reaction between the base catalyst and methanol is carried out, for example, by adding the base catalyst, and optionally methanol and a solvent, to the reaction solution obtained by the reaction between the acid catalyst and methanol, and stirring the mixture. The addition of the base catalyst changes the liquid property of the reaction solution from acidic to basic (pH greater than 7), allowing the reaction between the base catalyst and methanol to proceed.

[0047] When methanol is added, the amount of methanol used is preferably 0.5 to 50 in terms of the mass ratio relative to the triglycerides contained in POME, more preferably 1 to 40, even more preferably 2 to 20, and particularly preferably 3 to 10. The methanol used in the reaction with the acid catalyst and methanol, for example, unreacted methanol, can be used. In this case, the amount of methanol used when adding the methanol can be reduced depending on the amount of unreacted methanol. In one embodiment, the amount of methanol used in this case is preferably 0.5 to 40 in terms of the mass ratio, more preferably 1 to 30, even more preferably 1 to 20, 1 to 10, 2 to 20, 2 to 10, 3 to 20, or even more preferably 3 to 10. When methanol is not added, the methanol used in the reaction with the acid catalyst and methanol is also used in the reaction with the base catalyst and methanol.

[0048] Stirring is preferably carried out under heating, for example, at a temperature of 25° C. to 80° C., preferably 30° C. to 70° C., and more preferably 40° C. to 65° C. Stirring may also be carried out under pressure. Those skilled in the art can select preferred temperatures and pressures depending on the desired reaction time, etc.

[0049] The stirring time may be within a range in which the reaction with the base catalyst and methanol proceeds sufficiently, and those skilled in the art can appropriately select the stirring time depending on the reaction treatment method, the type of reactor, etc. For example, in the case of a batchwise reaction, the stirring time can be appropriately selected from the range of about 5 to 80 minutes, preferably about 10 to 60 minutes.

[0050] (3) Purification After the reaction is completed, the resulting reaction solution can be purified to obtain a product containing FAME, which allows impurities contained in POME to be removed.

[0051] The purification method is not particularly limited, but examples thereof include distillation, centrifugation, phase separation, washing with water, etc. These purification methods may be used alone or in combination of two or more.

[0052] For example, unreacted methanol is separated from the reaction liquid discharged from the reactor by vacuum distillation or the like, and the by-product glycerin, water, and catalyst residue that have phase-separated from the fatty acid methyl esters (FAME) are separated by decantation, centrifugation, solvent, or the like, and the product containing FAME is recovered.

[0053] If necessary, water may be added to the oil layer and the mixture may be stirred to wash the oil layer. The water washing is preferably carried out under heating, for example, by heating the oil layer to 40°C or higher and 80°C or lower, preferably 50°C or higher and 70°C or lower, and then adding water. If necessary, the water washing may be repeated several times.

[0054] Thereafter, if necessary, water can be removed by drying under reduced pressure or the like to obtain a product containing FAME.

[0055] The above-described methyl esterification process allows for the production of a product containing FAME in a high reaction yield, regardless of the presence of impurities in POME, and also allows for the efficient removal of impurities from the resulting reaction solution.

[0056] [Biofuel] Biofuel can be obtained by the methyl esterification process, which contains fatty acid methyl esters (FAME) and from which impurities have been removed.

[0057] The biofuel produced by the methyl esterification step may contain, in addition to FAME, unreacted substances such as glycerides and fatty acids, and by-products such as propanol and linear unsaturated hydrocarbons.

[0058] The FAME is derived from fatty acids constituting glycerides, fatty acids (free fatty acids contained in POME), etc. Note that the number of carbon atoms in the fatty acids usually does not change through the methyl esterification step.

[0059] As for FAME, C １４ ~C ２４ Saturated fatty acid methyl esters and C １６ ~C２４ It is preferable that the biofuel contains at least one unsaturated fatty acid methyl ester. From the viewpoint of obtaining a biofuel with a high cetane number, １６ ~C ２０ Saturated fatty acid methyl esters and C １６ ~C ２０ It is more preferable to contain at least one unsaturated fatty acid methyl ester, even more preferable to contain at least one selected from the group consisting of methyl myristate, methyl pentadecylate, methyl palmitate, methyl margarate, methyl stearate, methyl eicosanoate, methyl behenate, methyl oleate, methyl linoleate, methyl α-linolenate, and methyl γ-linolenate, and it is particularly preferable to contain at least one selected from the group consisting of methyl palmitate, methyl margarate, methyl stearate, and methyl eicosanoate. The above-mentioned FAME may be contained alone or in combination of two or more.

[0060] The content of FAME contained in the biofuel obtained by the methyl esterification step is preferably 80 mass % or more, and more preferably 90 mass % or more, based on the total mass of the biofuel.

[0061] The biofuel obtained by the methyl esterification step can be used as a biodiesel fuel (BDF) containing FAME, either as is or in a mixed form with other fuels, additives, etc. Furthermore, as will be described later, by further carrying out a hydrogenation step, the biofuel can be used as a biodiesel fuel (BDF) containing hydrogenated vegetable oil (HVO) or as a biodiesel fuel (BDF) containing FAME and HVO. That is, in one embodiment, the biofuel is a biodiesel fuel (BDF).

[0062] Furthermore, by adjusting the carbon number of the HVO, it can be used as sustainable aviation fuel (SAF). That is, in one embodiment, the biofuel is sustainable aviation fuel (SAF).

[0063] <Purification Step> In one embodiment, the production method according to the present invention may further include a purification step, which includes an adsorption step of contacting the material to be purified with an adsorbent. The purification step may further include a degumming step, a deodorizing step, and a deoxidizing step, as necessary.

[0064] The purification step may be carried out before or after the methyl esterification step. When the purification step is carried out before the methyl esterification step, the product to be purified is POME, and when the purification step is carried out after the methyl esterification step, the product to be purified is a product containing FAME.

[0065] In one embodiment, the method for producing biofuel further includes a POME purification step, which includes an adsorption step of contacting POME with an adsorbent prior to the methyl esterification step, thereby increasing the FAME yield (BDF yield) in the methyl esterification step.

[0066] The order of the steps in the purification step before the methyl esterification step is not particularly limited. In one embodiment, the purification step includes an adsorption step and a degumming step, in this order. Also, in one embodiment, the purification step includes an adsorption step and a deodorizing step, in this order. Also, in one embodiment, the purification step includes a degumming step and an adsorption step, in this order. Also, in one embodiment, the purification step includes a deodorizing step and an adsorption step, in this order. Also, in one embodiment, the purification step includes an adsorption step, a degumming step, and a deodorizing step, in this order. Also, in one embodiment, the purification step includes a degumming step, an adsorption step, and a deodorizing step, in this order. Also, in one embodiment, the purification step includes a degumming step, a deodorizing step, and an adsorption step, in this order. Also, in one embodiment, the purification step includes an adsorption step, a deodorizing step, and a degumming step, in this order. Also, in one embodiment, the purification step includes a deodorizing step, an adsorption step, and a degumming step, in this order. In one embodiment, the purification step includes a deodorization step, a degumming step, and an adsorption step in this order.

[0067] When the purification step is carried out before the methyl esterification step, it is preferable that the purification step does not include a deacidification step, since POME contains a relatively large amount of fatty acids compared to other biomass resources, and therefore, by not including a deacidification step, a decrease in the fatty acid content can be prevented.

[0068] In one embodiment, the biofuel production method further includes a FAME purification step, which includes an adsorption step of contacting the FAME product with an adsorbent after the methyl esterification step. This allows for the production of a high-quality biodiesel fuel with reduced impurities. Furthermore, when a hydrogenation step (described later) is performed, components that inhibit the hydrogenation reaction can be effectively removed, thereby improving the hydrogenation efficiency in the hydrotreating process.

[0069] The order of the steps in the purification step after the methyl esterification step is not particularly limited. In one embodiment, the purification step includes an adsorption step and a degumming step, in this order. Also, in one embodiment, the purification step includes an adsorption step and a deodorizing step, in this order. Also, in one embodiment, the purification step includes an adsorption step and a deoxidizing step, in this order. Also, in one embodiment, the purification step includes a degumming step and an adsorption step, in this order. Also, in one embodiment, the purification step includes a deodorizing step and an adsorption step, in this order. Also, in one embodiment, the purification step includes a deoxidizing step and an adsorption step, in this order. Also, in one embodiment, the purification step includes an adsorption step, a degumming step, and a deodorizing step, in this order. Also, in one embodiment, the purification step includes a degumming step, an adsorption step, and a deodorizing step, in this order. Also, in one embodiment, the purification step includes a degumming step, a deodorizing step, and an adsorption step, in this order. In one embodiment, the purification process includes an adsorption process, a deodorizing process, and a degumming process, in this order. In one embodiment, the purification process includes a deodorizing process, an adsorption process, and a degumming process, in this order. In one embodiment, the purification process includes a deodorizing process, a degumming process, and an adsorption process, in this order. In one embodiment, the purification process includes an adsorption process, a deoxidizing process, and a degumming process, in this order. In one embodiment, the purification process includes a deoxidizing process, an adsorption process, and a degumming process, in this order. In one embodiment, the purification process includes a deoxidizing process, a degumming process, and an adsorption process, in this order. In one embodiment, the purification process includes a degumming process, a deoxidizing process, and an adsorption process, in this order. In one embodiment, the purification process includes an adsorption process, a deoxidizing process, and a deodorizing process, in this order. In one embodiment, the purification process includes a deoxidizing process, an adsorption process, and a deodorizing process, in this order. In one embodiment, the purification process includes a deoxidation process, a deodorization process, and an adsorption process, in this order. In one embodiment, the purification process includes an adsorption process, a degumming process, a deodorization process, and a deoxidation process, in this order. In one embodiment, the purification process includes a deoxidation process, an adsorption process, a degumming process, and a deodorization process, in this order. In one embodiment, the purification process includes a degumming process, a deoxidization process, an adsorption process, and a deodorization process, in this order.

[0070] In addition, when the purification step is carried out after the methyl esterification step, the purification step can include a deacidification step, since the fatty acids have been converted into fatty acid methyl esters (FAME) in the methyl esterification step.

[0071] [Adsorption Step] The adsorption step is a step in which palm oil mill effluent (POME) or a product containing FAME (hereinafter also simply referred to as "material to be purified") is brought into contact with an adsorbent.

[0072] (Adsorbent) The adsorbent has a function of removing impurities contained in the product to be purified and components that inhibit the hydrogenation reaction by adsorbing them.

[0073] The adsorbent is not particularly limited, but examples thereof include activated clay, acid clay, silica, activated carbon, activated alumina, aluminum silicate, etc. These adsorbents may be used alone or in combination of two or more.

[0074] Acid clay is a silicate mineral, monoclinic montmorillonite. Acid clay (montmorillonite) includes tetrahedral sheets formed by two-dimensionally connecting tetrahedral structures, each of which has a silicon ion at the center of a tetrahedron formed by four oxygen ions, and octahedral sheets formed by two-dimensionally connecting octahedral structures, each of which has an aluminum ion, magnesium ion, or the like at the center of an octahedron formed by four oxygen ions and two hydroxide ions, with the edges shared. In this case, one octahedral sheet is formed between two tetrahedral sheets, and exchangeable cations and water molecules exist between each sheet (each crystalline layer). Commercially available acid clay products include Mizuka Ace #20 and Mizuka Ace #400 (manufactured by Mizusawa Industrial Chemicals Co., Ltd.). Activated clay can also be obtained by heat-treating acid clay with an acid (sulfuric acid, hydrochloric acid, etc.). By subjecting acid clay to heat treatment with an acid, it can be made porous, and the activated clay has better adsorption properties. Commercially available activated clay products include Galleon Earth RS, Galleon Earth GSF, Galleon Earth V2R, and Galleon Earth NV (manufactured by Mizusawa Industrial Chemicals, Ltd.).

[0075] The adsorbent preferably contains at least one selected from the group consisting of activated clay, acid clay, silica, and activated carbon, more preferably contains at least one selected from the group consisting of activated clay, acid clay, and silica, and even more preferably contains activated clay from the viewpoint of being able to efficiently remove impurities contained in the product to be purified and components that inhibit the hydrogenation reaction.

[0076] The specific surface area of ​​the adsorbent is 200 m ２ / g or more, and ２ / g or more 800m ２ / g or less is more preferable, and 250m ２ / g or more 400m ２ / g or less. In this specification, the "specific surface area" is measured by the BET method. ２ ) is used.

[0077] The amount of adsorbent used is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 7.5% by mass or less, and even more preferably 0.5% by mass or more and 5% by mass or less, based on the total mass of the product to be purified.

[0078] (Contact) The method for contacting the material to be purified with the adsorbent is not particularly limited. For example, when the material to be purified is liquid, it is preferable to add the adsorbent to the material to be purified and mix them. Furthermore, when the material to be purified is dry, it is preferable to dilute the material to be purified with water, add the adsorbent, and mix them, from the viewpoint of increasing the contact efficiency.

[0079] The temperature during contact is not particularly limited, but is preferably 1°C or higher and 150°C or lower, more preferably 10°C or higher and 120°C or lower, even more preferably 40°C or higher and 100°C or lower, and particularly preferably 60°C or higher and 100°C or lower.

[0080] The pressure during contact is preferably a reduced pressure condition, more preferably 1 mmHg or more and 600 mmHg or less, even more preferably 1 mmHg or more and 300 mmHg or less, particularly preferably 1 mmHg or more and 100 mmHg or less, and extremely preferably 5 mmHg or more and 50 mmHg or less. Note that the pressure means absolute pressure.

[0081] The rotation speed of the stirrer during contact is preferably 50 rpm or more and 600 rpm or less, more preferably 100 rpm or more and 500 rpm or less, and even more preferably 150 rpm or more and 400 rpm or less.

[0082] The contact time is preferably from 5 to 60 minutes, more preferably from 10 to 50 minutes, even more preferably from 15 to 40 minutes, and particularly preferably from 20 to 30 minutes.

[0083] After the contact, the adsorbent is removed by centrifugation, filtration, etc., and then the mixture is dried to obtain a product containing purified POME or purified FAME.

[0084] [Degumming Process] The degumming process is a process for hydrating and removing gums, mainly composed of phospholipids, contained in the product to be purified. The degumming process is not limited, but can be carried out, for example, by adding steam or water to the product to be purified, stirring the mixture, and removing the aqueous layer. The degumming process may also be carried out by adding a degumming agent. Examples of degumming agents that can be used include aqueous solutions of acids such as oxalic acid, citric acid, and phosphoric acid.

[0085] [Deodorization Step] The deodorization step is a step of removing odorous components contained in the product to be purified. The deodorization step is not limited, but can be carried out, for example, by steam distillation under reduced pressure.

[0086] [Deacidification Step] The deacidification step is a step in which a mixture of an aqueous solution containing an alkaline substance and a product to be purified is stirred, and then the aqueous phase is separated and removed.

[0087] The alkaline substance is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium hydrogen carbonate, etc. These alkaline substances may be used alone or in combination of two or more.

[0088] The amount of alkaline substance added is preferably such that the ratio of the alkaline substance added to the neutralization equivalent of the acidic substance contained in the product to be purified is 1.0 or more and 1.4 or less, more preferably 1.0 or more and 1.3 or less, and even more preferably 1.1 or more and 1.3 or less.

[0089] [Purified POME] When the purification step is carried out before the methyl esterification step, purified POME can be obtained by the purification step. Since impurities have been removed from the purified POME by the purification step, the subsequent methyl esterification step can proceed efficiently. Note that when the purification step is carried out before the methyl esterification step, the above-mentioned methyl esterification step is carried out by replacing "POME" with "purified POME."

[0090] [Purified FAME-containing product] When the purification step is performed after the methyl esterification step, a purified FAME-containing product can be obtained by the purification step. The purified FAME-containing product has reduced impurities and is therefore a high-quality biofuel. The purified FAME-containing product can be used as a FAME-containing biodiesel fuel (BDF) either as is or in a form mixed with other fuels, additives, etc. Furthermore, when the hydrogenation step described below is performed, components that inhibit the hydrogenation reaction can be effectively removed, thereby improving the hydrogenation efficiency in the hydrotreating process.

[0091] The content of FAME contained in the FAME-containing product refined by the refining process (biofuel obtained by the refining process) is preferably 85 mass% or more, and more preferably 95 mass% or more, relative to the total mass of the FAME-containing product.

[0092] <Hydrogenation Step> In one embodiment, the production method according to the present invention may further include a hydrogenation step of hydrotreating the product containing FAME.

[0093] The hydrogenation step is carried out at least after the methyl esterification step. In one embodiment, the production method according to the present invention comprises a methyl esterification step and a hydrogenation step, in this order. In another embodiment, the production method according to the present invention comprises a methyl esterification step, a FAME purification step, and a hydrogenation step, in this order. In another embodiment, the production method according to the present invention comprises a POME purification step, a methyl esterification step, and a hydrogenation step, in this order.

[0094] The hydrogenation step is a step of hydrogenating a product containing FAME. This step reduces unsaturated groups (double bonds) in FAME, glycerides, fatty acids, etc., decomposes FAME and glycerides to produce fatty acids, and reduces fatty acids, removes carbon monoxide, or decarboxylates them to produce linear saturated hydrocarbons. This allows linear saturated hydrocarbons useful for biofuels to be produced from the product containing FAME.

[0095] [FAME-containing product] The FAME-containing product can be obtained by a methyl esterification step. If a purification step is performed after the methyl esterification step, the purified FAME-containing product is used.

[0096] [Hydrogenation Treatment] Hydrogenation treatment is preferably carried out by adding hydrogen in an amount sufficient to saturate the unsaturated components in the FAME-containing product.

[0097] The hydrotreatment is preferably carried out in the presence of a catalyst.

[0098] The catalyst preferably contains one or more metals selected from Groups 7 to 10 of the periodic table, and more preferably contains at least one metal selected from the group consisting of iridium, palladium, platinum, rhenium, rhodium, ruthenium, and nickel.

[0099] The metal may be supported on a catalyst support, and the amount of the metal supported is preferably 1 mass % or more and 20 mass % or less, more preferably 2 mass % or more and 10 mass % or less, and even more preferably 3 mass % or more and 5 mass % or less, relative to the mass of the catalyst support.

[0100] The catalyst support is not particularly limited as long as it is a solid inert material capable of supporting the catalyst metal. Examples include metal oxides (e.g., silica, alumina, zeolite, titania, etc.) and activated carbon. The catalyst support can be used in the form of powder, granules, pellets, etc.

[0101] The catalyst can be prepared by impregnation, for example, by adding a hydrochloric acid solution of a metal chloride to a catalyst support to achieve a predetermined loading amount, stirring, drying at about 60°C to 80°C for about 1 to 3 hours, further drying at about 90°C to 110°C for about 5 to 48 hours, and then calcining at about 400°C to 600°C for about 1 to 5 hours.

[0102] The metal chloride is not limited as long as it contains the above metal. For example, ruthenium chloride (RuCl ３ ・3H ２ O), rhodium chloride (RhCl ３ ・3H ２ O), palladium chloride (PdCl ２ ), chloroiridic acid (H ２ IrCl ６ ), chloroplatinic acid (H ２ PtCl ６ ) etc.

[0103] The amount of catalyst (including the metal and catalyst support) used is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 30% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less, based on the mass of the substrate.

[0104] The catalyst may optionally contain one or more promoters. More preferably, the promoter contains one or more metals selected from Groups 6 to 10 of the periodic table. The promoter may be provided in the form of a salt or an acid, for example, as an oxyanion of perrhenic acid, molybdic acid, tungstic acid, or the like.

[0105] The co-catalyst may be supported on a catalyst carrier, or may be further supported on a carrier supporting the catalytic metal. The molar ratio of the amount of the metal to the catalytic metal is preferably 0.1 to 10, more preferably 0.5 to 6, and even more preferably 0.8 to 4.

[0106] The promoter can be supported on the catalyst carrier by impregnation, similarly to the catalytic metal.

[0107] For example, the catalyst carrier can be prepared by adding an aqueous solution of the co-catalyst to the catalyst carrier in advance so that a predetermined amount of the co-catalyst is loaded, stirring the mixture, drying the mixture at about 60°C or higher and 80°C or lower for about 1 to 3 hours, further drying the mixture at about 90°C or higher and 110°C or lower for about 5 to 48 hours, and then calcining the mixture at about 400°C or higher and 600°C or lower for about 1 to 5 hours.

[0108] Alternatively, when a co-catalyst is further supported on the support supporting the catalytic metal, an aqueous solution of the co-catalyst is added to the support supporting the catalyst after drying and before calcination so as to achieve a predetermined loading amount, followed by stirring, drying at about 60°C or higher and 80°C or lower for about 1 to 3 hours, further drying at about 90°C or higher and 110°C or lower for about 5 to 48 hours, and after drying, calcining at about 400°C or higher and 600°C or lower for about 1 to 5 hours, thereby preparing the catalyst support.

[0109] The above description is merely an example, and a person skilled in the art can appropriately select the types, combinations, amounts of the catalyst, co-catalyst and catalyst support, preparation methods, etc. in order to optimize the hydrogenation reaction.

[0110] The hydrotreating can be carried out in the presence or absence of a solvent.

[0111] When a solvent is used, any solvent commonly used in hydrogenation reactions can be used. For example, ５ ~C１２ Hydrocarbon solvents, such as hexane, cyclohexane, dodecane; ４ ~C ８ Ethers, such as tetrahydrofuran, methyl t-butyl ether; ４ ~C １０ Esters, for example, ethyl acetate; chlorinated C １ ~C ２ Hydrocarbons, for example, dichloromethane; ２ ~C ６ Examples of suitable solvents include primary or secondary alcohols, such as isopropanol and ethanol, and other polar solvents, such as dimethylformamide, acetonitrile, dimethyl sulfoxide, and acetone, or mixtures thereof. Those skilled in the art can select an appropriate solvent to optimize the hydrogenation reaction in each case depending on the type of catalyst, etc.

[0112] Hydrogenation is carried out at a pressure of 0.1 MPa to 30 MPa. ２ It is preferable to carry out the reaction at a pressure of 0.5 MPa to 3 MPa, more preferably 0.5 MPa to 2.5 MPa, and particularly preferably 1 MPa to 2.5 MPa. Those skilled in the art can adjust the pressure depending on the catalyst loaded and the dilution of the substrate in the solvent. The pressure mentioned above means a gauge pressure.

[0113] The temperature at which the hydrogenation treatment is carried out is preferably 50° C. to 400° C., more preferably 100° C. to 200° C., and even more preferably 150° C. to 200° C. Those skilled in the art can select a preferred temperature depending on the desired reaction time, etc.

[0114] The hydrogenation treatment is preferably carried out in an atmosphere consisting of only hydrogen gas, but may also be carried out in a mixed gas containing an inert gas such as nitrogen or argon, as long as it does not affect the hydrogenation reaction.

[0115] The reaction is preferably carried out continuously. The reaction is preferably carried out with stirring. The stirring method can be appropriately selected depending on the purpose, and known stirring methods can be used.

[0116] After the hydrogenation reaction is completed, the reaction mixture is recovered using a solvent, which may be the same as that used in the hydrogenation treatment.

[0117] [Biofuels] Biofuels can be obtained by a hydrogenation process.

[0118] The biofuel obtained by the hydrogenation step contains linear saturated hydrocarbons and may further contain unreacted substances such as FAME, glycerides, and fatty acids, as well as by-products such as propanol and linear unsaturated hydrocarbons.

[0119] The linear saturated hydrocarbons are derived from FAME, fatty acids constituting glycerides, fatty acids (free fatty acids contained in POME), etc. Note that the number of carbon atoms in the fatty acid usually remains unchanged or decreases by one after the hydrogenation reaction.

[0120] The linear saturated hydrocarbon preferably includes at least one selected from the group consisting of heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, henicosane, docosane, tricosane, and tetracosane, and more preferably includes at least one selected from the group consisting of hexadecane, heptadecane, octadecane, nonadecane, and eicosane. The linear saturated hydrocarbons described above may be included alone or in combination of two or more.

[0121] The biofuel obtained by the hydrogenation process can be used as it is or in a form mixed with other fuels, additives, etc. as a biodiesel fuel (BDF) containing hydrogenated vegetable oil (HVO) or a BDF containing FAME and HVO. In addition, by adjusting the carbon number of the hydrogenated vegetable oil (HVO), it can be used as a sustainable aviation fuel (SAF).

[0122] When used as sustainable aviation fuel (SAF), it is processed to meet the SAF specifications by isomerization / hydrocracking, as described below.

[0123] <Isomerization / Hydrocracking Step> In one embodiment, the production method according to the present invention may further include an isomerization / hydrocracking step in which the hydrocarbons obtained in the hydrogenation step are isomerized or hydrocrackered.

[0124] The isomerization / hydrocracking step is carried out after the hydrogenation step. In one embodiment, the production method according to the present invention comprises a methyl esterification step, a hydrogenation step, and an isomerization / hydrocracking step, in this order. In another embodiment, the production method according to the present invention comprises a methyl esterification step, a FAME purification step, a hydrogenation step, and an isomerization / hydrocracking step, in this order. In another embodiment, the production method according to the present invention comprises a POME purification step, a methyl esterification step, a hydrogenation step, and an isomerization / hydrocracking step, in this order.

[0125] The isomerization / hydrocracking step is a step in which the hydrocarbons obtained in the hydrogenation step are isomerized or hydrocracking, thereby producing biofuel that meets the specifications for sustainable aviation fuel (SAF).

[0126] In this step, the hydrocarbons (preferably linear saturated hydrocarbons) contained in the biofuel obtained by the hydrogenation step are converted by isomerization or hydrocracking into desired hydrocarbons, i.e., isoparaffins containing one or more methyl groups in the molecule or paraffins with a lower carbon number, so as to have a high flash point and good flow properties in cold temperatures.

[0127] Isomerization and hydrocracking are well-known techniques, and those skilled in the art can select appropriate catalysts and reaction conditions to meet the specifications of various fuels.

[0128] Isomerization converts hydrocarbons (preferably linear saturated hydrocarbons) into isoparaffins, thereby lowering the freezing point. Isomerization can be carried out in the presence of an acidic catalyst. As the isomerization catalyst, a bifunctional catalyst having metal sites for hydrogenation / dehydrogenation and acid sites for skeletal isomerization via carbocation is preferably used. For example, Pt / SAPO-11 / Al ２ O ３ , Pt / ZSM-22 / Al ２ O３ , Pt / ZSM-23 / Al ２ O ３ , and Pt / SAPO-11 / SiO ２ etc.

[0129] Typically, hydrocarbons (preferably linear saturated hydrocarbons) are dehydrogenated over the metal sites of the catalyst and react on the acid sites to form alkyl carbocations, producing protonated olefins. The alkyl carbocations rearrange to mono-, di-, and tri-branched alkyl carbocations on the acid sites. The branched alkyl carbocations are deprotonated and hydrogenated to produce the corresponding isoparaffins.

[0130] Hydrocracking is an exothermic reaction that produces liquid or gaseous shorter carbon number paraffins from hydrocarbons (preferably linear saturated hydrocarbons). Because the reaction is relatively slow, most of the hydrocracking takes place in the final section of the reactor. Hydrocracking primarily involves the cracking and saturation of hydrocarbons (preferably linear saturated hydrocarbons). Excessive cracking can result in the production of lower paraffins (C １ ~C ４ ) and naphtha (C ５ ~C ８ ) is produced, which is undesirable.

[0131] After the isomerization / hydrocracking step, the mixture was treated with paraffinic kerosene (C ９ ~C １６ ), paraffinic diesel (C １６ ~C １８ ), naphtha and light gases. ７ ~C １６ ) can then be distilled and used as the SAF.

[0132] Biofuels Biofuels can be obtained by the isomerization / hydrocracking process, which is sustainable aviation fuel (SAF).

[0133] The biofuel obtained by the isomerization / hydrocracking process contains paraffins and isoparaffins. It may also contain other raw material-derived components such as FAME, glycerides, fatty acids, propanol, and linear unsaturated hydrocarbons. The biofuel may also contain other fuels, additives, and the like, as needed.

[0134] The paraffin is C ７ ~C １６ Linear saturated hydrocarbons (paraffins) and C ７ ~C １６ Preferably, the branched chain saturated hydrocarbon (isoparaffin) of ９ ~C １６ Linear saturated hydrocarbons and C ９ ~C １６ It is more preferable that the branched chain saturated hydrocarbons contain at least one selected from the group consisting of the following: The above-mentioned paraffins and / or isoparaffins may be contained alone or in combination of two or more thereof.

[0135] 2. Method for Removing Impurities from POME According to one aspect of the present invention, there is provided a method for removing impurities from palm oil mill effluent (POME). The method includes a methyl esterification step in which POME is reacted with an acid catalyst and methanol, and then with a base catalyst and methanol to produce fatty acid methyl esters (FAME). According to the method for removing impurities from POME, the methyl esterification step can reduce the impurities contained in POME, preferably to 0.01% by mass or less, and more preferably to 0.001% by mass or less.

[0136] The impurities to be removed may be, for example, at least one selected from the group consisting of alkali metals, alkaline earth metals, semi-metals or non-metals, transition metals, and halogens. Specifically, the impurities may be at least one selected from the group consisting of Na, Mg, Ca, Ba, B, Al, P, Cr, Mn, Fe, Cu, Zn, Mo, and Cd. In one embodiment, the impurities to be removed include an alkali metal, such as Na. In one embodiment, the impurities to be removed include an alkaline earth metal, such as at least one of Mg, Ca, and Ba. In one embodiment, the impurities to be removed include a semi-metal or non-metal, such as at least one of B, Al, and P. In one embodiment, the impurities to be removed include a transition metal, such as at least one selected from the group consisting of Cr, Mn, Fe, Cu, Zn, Mo, and Cd. The above-mentioned impurities to be removed may be contained alone or in combination of two or more.

[0137] The methyl esterification step according to the present invention can produce FAME in a high reaction yield regardless of the impurities contained in POME. Furthermore, by carrying out the methyl esterification step, glycerides, fatty acids, and the like contained in POME are converted into fatty acid methyl esters (FAME), which makes it possible to easily remove impurities.

[0138] The method may further include a POME purification step, which includes an adsorption step of contacting POME with an adsorbent prior to the methyl esterification step. In this case, the purification step may include a degumming step and a deodorizing step. The methyl esterification step and the purification step are as described above, and therefore will not be described again here.

[0139] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0140] [Production Example 1] A catalyst to be used in the hydrogenation step was prepared by the impregnation method as follows.

[0141] 1 g of silicon dioxide (silica gel "CARiACT G-6" manufactured by Fuji Silysia Chemical Ltd.) that had been pre-calcined at 700°C (973K) using a muffle furnace was weighed out and placed in a beaker.

[0142] Iridium (IV) chloride hydrochloride acid solution (H ２ IrCl ６ HCl) (obtained from Furuya Metal Co., Ltd.) was added dropwise to the mixture so that the amount of Ir supported was 4 mass %, and after thorough stirring, the water was evaporated at around 70° C. Then, the mixture was dried at 100° C. for one day.

[0143] After drying, an aqueous solution of ammonium perrhenate (NH ４ ReO ４ aq) (obtained from Mitsuwa Chemical Co., Ltd.) was added dropwise so that the molar ratio of Ir to Re was 1:1. After thorough mixing, the water was evaporated at around 70°C, and the mixture was dried at 100°C for 5 hours or more. After confirming that the drying was complete, the mixture was calcined at 500°C (773K) for 3 hours to obtain the catalyst (Ir-Re SiO ２ ) was prepared.

[0144] Example 1 A biofuel containing FAME was produced by carrying out a methyl esterification process.

[0145] (Methyl esterification step) 200 g of raw material (POME (dried product)) was placed in a 500 mL Erlenmeyer flask and heated to 60°C. Methanol and concentrated sulfuric acid as an acid catalyst were then added in amounts of 20 and 0.2 relative to the amount of free fatty acid contained in the raw material, respectively, and the mixture was stirred with a stirrer for 60 minutes.

[0146] Thereafter, methanol was added so that the molar ratio relative to the molar amount of triglyceride contained in the raw material was 5, and potassium hydroxide as a base catalyst was added in an amount equivalent to neutralization of concentrated sulfuric acid so that the molar ratio relative to the triglyceride was 0.24, followed by stirring for 30 minutes at 60° C. Note that the amount of potassium hydroxide added exceeded the neutralization equivalent of concentrated sulfuric acid, and the reaction solution became alkaline.

[0147] The reaction solution was transferred to a 500 mL separatory funnel and allowed to stand at room temperature (25 ° C) for 40 minutes for separation, and the lower layer was removed. The upper layer was placed in a 500 mL Erlenmeyer flask, heated to 60 ° C, and 22% by mass of distilled water relative to the raw material was added, and the mixture was washed with water by stirring for 20 minutes. After washing with water, the reaction solution was transferred to a 500 mL separatory funnel and allowed to stand at room temperature (25 ° C) for 40 minutes for separation, and the lower layer was removed. The upper layer was again placed in a 500 mL Erlenmeyer flask, washed with water under the same conditions, and the lower layer was separated and removed. The resulting upper layer was dried at 105 ° C and atmospheric pressure (760 mmHg) for 60 minutes to produce biofuel.

[0148] The amount (mol) of free fatty acid contained in the raw material was calculated by calculating the content of free fatty acid in the raw material using the following formula 1, determining the content of free fatty acid contained in the raw material from the content, and then converting it into oleic acid (molecular weight 282.46 g / mol). Formula 1: Free fatty acid content (%) = Acid value of raw material × Conversion coefficient of free fatty acid (oleic acid) (0.503)

[0149] The amount of triglyceride (mol) contained in the raw material was calculated by calculating the triglyceride content in the raw material using the following formula 2, determining the triglyceride content in the raw material from the calculated content, and then converting it into triolein (molecular weight 885.432 g / mol). Formula 2: Triglyceride content (%) = 100 - free fatty acid content (%) calculated using formula 1

[0150] Example 2 A biofuel containing FAME was produced by carrying out a methyl esterification step followed by an adsorption step.

[0151] (Methyl Esterification Step) The methyl esterification step was carried out in the same manner as in Example 1 to produce a product containing FAME.

[0152] (Adsorption step) 150 g of the raw material (FAME-containing product) was placed in a 300 mL three-neck flask, heated to 80°C, and then activated clay ("Galleon Earth RS" manufactured by Mizusawa Industrial Chemicals, pH: 3, specific surface area: 330 m) was added as an adsorbent. ２ / g) was added in an amount of 2 mass % based on the raw materials.

[0153] The mixture was then stirred at 300 rpm using a stirring blade at 80°C under a reduced pressure of 10 mmHg absolute for 30 minutes, and then filtered under reduced pressure using a Kiriyama funnel (No. 5A filter paper) to produce a biofuel containing FAME.

[0154] Example 3 A biofuel containing FAME was produced by carrying out an adsorption step followed by a methyl esterification step.

[0155] (Adsorption Step) The adsorption step was carried out in the same manner as in Example 2, except that POME (dried product) was used as the raw material, to obtain purified POME.

[0156] (Methyl Esterification Step) A biofuel containing FAME was produced by carrying out a methyl esterification step in the same manner as in Example 1, except that 183.3 g of purified POME was used as the raw material.

[0157] [Evaluation] For Examples 1 to 3, the BDF yield, composition analysis, and impurity evaluation were carried out.

[0158] (BDF Yield) The yield of biodiesel fuel (BDF) (BDF yield) in the methyl esterification step was calculated.

[0159] Specifically, the BDF yield was calculated from the raw material used in the methyl esterification step and the yield (g) of BDF (biofuel containing FAME) obtained in the methyl esterification step using the following formula: BDF yield (mass%) = BDF yield (g) / raw material charge amount in the methyl esterification step (g) × 100

[0160] The results obtained are shown in Table 1 below.

[0161] The results in Table 1 show that biofuel (BDF) containing FAME was produced in high yields by the methyl esterification using the acid-alkali method in Examples 1 to 3. Furthermore, it is believed that impurities were removed from the biofuel (BDF) by the refining performed after the completion of the reaction using the acid-alkali method.

[0162] Furthermore, it can be seen that purifying POME by the adsorption step before the methyl esterification step improves the BDF yield in the methyl esterification step. Note that in Examples 1 and 2, the same raw materials were used and the same reaction was carried out in the methyl esterification step, so the results were the same.

[0163] (Composition Analysis) The biofuels containing FAME produced in Examples 1 to 3 were further subjected to a hydrogenation step to obtain biofuels containing FAME and hydrogenated vegetable oil (HVO). The composition of the obtained biofuels containing FAME and HVO was analyzed.

[0164] Hydrogenation Step The hydrogenation step for the biofuels containing FAME produced in Examples 1 to 3 was carried out in the following manner.

[0165] 0.15 g of the catalyst prepared in Preparation Example 1 was weighed into a glass reaction tube, followed by 1.0 g of the biofuel containing FAME produced in the Example. 9.0 g of cyclohexane was added. A stir bar was placed in the autoclave vessel. Hydrogen gas was sealed in the vessel at 2 MPa, and the reaction was carried out at 180°C (453K) for 3 hours. The stirring speed was 500 rpm. After the reaction was completed, the reaction solution was cooled and recovered with 15 g of cyclohexane, producing a biofuel containing FAME and HVO.

[0166] Composition Analysis Composition analysis of biofuels containing FAME and HVO was carried out by the following method.

[0167] 0.1 g of nonadecane was added as an internal standard to the biofuel containing FAME and HVO, and gas chromatographic (GC) analysis was carried out according to the following procedure.

[0168] <Gas chromatograph (GC) analysis> The biofuel was filtered through a 0.45 μm polytetrafluoroethylene (PTFE) membrane filter and then analyzed by gas chromatography (GC). When the solubility was poor, the biofuel was diluted with chloroform and then subjected to analysis.

[0169] The analytical conditions were as follows: Instrument: Gas chromatograph "GC-2010" (Shimadzu Corporation) Analysis: Analysis data system "LabSolutions GC" (Shimadzu Corporation) Column: GC column "DB-5HT" (length 15 m, inner diameter 0.32 mm, film thickness 0.10 μm) (Agilent Technologies Inc.) Heating conditions: After holding at 80°C for 10 minutes, heat up to 350°C at a rate of 10°C / min, then hold at 350°C for 20 minutes Detector: FID (flame ionization detector) Carrier gas: He Injection method: Split Injection amount: 1 μL

[0170] A calibration curve was prepared for each compound to be analyzed, and the compounds were quantified using the internal standard method.

[0171] The carbon-based yield (C mol %) of each component was calculated from the quantitative values. The yield was calculated using the following formula: Carbon-based yield (C mol %) = number of carbon moles of the component of interest (C mol) / number of carbon moles calculated from the fatty acid composition of POME (dry product) (C mol) × 100

[0172] The carbon-based yields of the hydrocarbons of interest were added together to give the total yield of hydrocarbons obtained in the hydrogenation step. The results are shown in Tables 2 and 3. Note that, as Reference Example 1, the composition of the biofuel obtained by hydrotreating POME (dry product) in the hydrogenation step is also shown.

[0173]

[0174]

[0175] The results in Tables 2 and 3 show that in Examples 1 to 3, impurities were removed from the biofuel (biofuel containing FAME) used as the feedstock for hydrotreating by the methyl esterification step (and the adsorption step), thereby improving the hydrogenation efficiency in the subsequent hydrogenation step.

[0176] (Evaluation of Impurities) The biofuels containing FAME produced in Examples 1 to 3 were evaluated for impurities.

[0177] Specifically, the impurity components contained in the biofuel containing FAME were analyzed by high-frequency inductively coupled plasma (ICP) emission spectrometry.

[0178] <ICP Atomic Emission Analysis> The biofuels containing FAME produced in Examples 1 to 3 were treated with a 0.45 μm polytetrafluoroethylene (PTFE) membrane filter, diluted with a 5-fold amount of xylene, and subjected to analysis.

[0179] The analytical conditions were as follows: Instrument: ICP optical emission spectrometer "SPECTRO ARCOS SOP" (Hitachi High-Tech Science Corporation) Analysis: analytical data system "Smart Analyzer Vision" (Hitachi High-Tech Science Corporation) Gas: argon gas Plasma gas flow rate: 15.00 L / min Nebulizer gas flow rate: 0.50 L / min Auxiliary gas: 1.50 L / min Plasma power: 1550 W Calibration curve reagent: CONOSTAN (Oil Analysis Standards) S-2 1500 ppm (wt.) 75 cst (GL Sciences Inc.)

[0180] A calibration curve was prepared for each of the impurity components to be analyzed, and the components were quantified using the external standard method. The calibration curve was prepared using rapeseed refined oil "AJINOMOTO Smooth Canola Oil" (manufactured by J Oil Mills Co., Ltd.). Reference Example 2 also shows the results of impurity evaluation of unrefined POME (POME (dry product)).

[0181]

[0182] The results in Table 4 show that the impurity contents in Examples 1 to 3 are lower than in Reference Example 2.

Claims

1. A method for producing biofuel, comprising a methyl esterification step of reacting palm oil mill effluent (POME) with an acid catalyst and methanol, and then with a base catalyst and methanol to produce fatty acid methyl esters (FAME).

2. The process according to claim 1, further comprising a step of purifying POME, the step including an adsorption step of contacting POME with an adsorbent, prior to the methyl esterification step.

3. The method of claim 1, further comprising a step of purifying FAME after the methyl esterification step, the step including an adsorption step of contacting the product containing FAME with an adsorbent.

4. The process of claim 1, further comprising a hydrogenation step of hydrotreating the product containing FAME.

5. The method for producing a biofuel according to claim 1, wherein the biofuel is a biodiesel fuel.

6. A method for removing impurities from palm oil mill effluent (POME), comprising a methyl esterification step of reacting POME with an acid catalyst and methanol, and then with a base catalyst and methanol to produce fatty acid methyl esters (FAMEs).

7. The method for removing impurities from POME according to claim 6, further comprising a step of purifying POME, prior to said methyl esterification step, comprising an adsorption step of contacting POME with an adsorbent.

8. The method for removing impurities from POME according to claim 6, further comprising a step of purifying FAME after the methyl esterification step, the step including an adsorption step of contacting the product containing FAME with an adsorbent.