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 waste cooking oil, POME, or fatty acids from non-edible palm oil. Patent Document 1 also describes separating gums when POME is used as a raw material.

[0008] JP 2022-45854 A

[0009] When biofuel is produced using POME, for example, hydrogenated vegetable oil (HVO) can be produced by separating and purifying the gums and other substances contained in POME, followed by hydrogenation treatment.

[0010] The separation of gums is usually carried out by a degumming process, which can be carried out by stirring the crude oil in water or steam in the presence of a degumming agent (an acidic compound such as oxalic acid, citric acid, or phosphoric acid) and removing the aqueous phase.

[0011] However, when POME is subjected to a degumming process and then hydrogenated, the hydrogenation efficiency is not improved, and in some cases, the hydrogenation efficiency is decreased. In such cases, it is not possible to efficiently produce hydrogenated vegetable oil (HVO) from POME.

[0012] Therefore, the present invention provides a method for efficiently hydrotreating POME.

[0013] The present inventors have found that by carrying out an adsorption step as a purification step of POME, components contained in POME that inhibit the hydrogenation reaction can be effectively removed, and the hydrogenation efficiency in the hydrotreatment of POME can be improved.

[0014] [1] A method for producing a biofuel, comprising: (a) a refining step of palm oil mill effluent (POME), comprising an adsorption step of contacting POME with an adsorbent; and (b) a hydrogenation step of hydrotreating the refined POME. [2] The production method according to [1] above, wherein the adsorbent comprises at least one selected from the group consisting of activated clay, acid clay, silica, and activated carbon. [3] The method for producing a biofuel according to [1] or [2] above, wherein the biofuel is selected from the group consisting of hydrogenated vegetable oil (HVO) and sustainable aviation fuel (SAF). [4] The method for producing a biofuel according to any of [1] to [3] above, wherein the biofuel is sustainable aviation fuel (SAF), and the production method further comprises: (c) an isomerization / hydrocracking step of isomerizing or hydrocracking the hydrocarbons obtained in the hydrogenation step. [5] A method for improving hydrogenation efficiency in the hydrotreatment of palm oil mill effluent (POME), comprising: (a) a purifying step of POME, including an adsorption step of bringing POME into contact with an adsorbent; and (b) a hydrogenation step of hydrotreating the purified POME. [6] A method for producing refined palm oil mill effluent (POME) for use in the production of biofuel, comprising: (a) a purifying step of POME, including an adsorption step of bringing POME into contact with an adsorbent, wherein the biofuel is produced by hydrotreating the refined POME.

[0015] According to the present invention, a method for efficiently hydrotreating POME and the like are provided.

[0016] 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.

[0017] 1. Method for Producing Biofuel The method for producing biofuel according to the present invention comprises: (a) a palm oil mill effluent (POME) purification step, which includes an adsorption step of bringing POME into contact with an adsorbent; and (b) a hydrogenation step of hydrotreating the purified POME.

[0018] <(a) Refining Step> The refining step includes an adsorption step in which palm oil mill effluent (POME) is brought into contact with an adsorbent. The refining step may further include, in addition to the adsorption step, at least one step selected from the group consisting of a degumming step and a deodorizing step. It is preferable that the refining step does not include a deacidification step. In this case, the deacidification step is a step of stirring a mixture of POME and an aqueous solution containing an alkaline substance (sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, etc.), followed by separating and removing the aqueous phase. POME contains a relatively high 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.

[0019] By carrying out the purification step, components contained in POME that inhibit the hydrogenation reaction can be effectively removed, thereby improving the hydrogenation efficiency in the subsequent hydrogenation step.

[0020] [Adsorption Step] The adsorption step is a step in which palm oil mill effluent (POME) is brought into contact with an adsorbent.

[0021] (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.

[0022] POME may be in liquid or dried form, but is preferably a dried product from the viewpoints of transportation costs, adsorption efficiency, etc. In this specification, "dried product" includes dehydrated cake. Dried POME can be produced by dehydrating a raw POME solution. Examples of dehydration treatments 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 treatments 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.

[0023] POME contains glycerides, fatty acids, and impurities, and may also contain fuel components such as palm kernel shells (PKS) and wood flour.

[0024] 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 ２０ It 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.

[0025] 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.

[0026] 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 ２０It 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Among the above, the component contained in POME that inhibits the hydrogenation reaction is typically an impurity, and is, for example, at least one selected from the group consisting of alkali metals, alkaline earth metals, metalloids or nonmetals, transition metals, and halogens, and specifically, at least one selected from the group consisting of Na, Ca, Ba, B, P, Cr, Mn, Fe, Cu, Zn, Mo, and Cd. In one embodiment, the component contained in POME that inhibits the hydrogenation reaction includes an alkali metal, such as Na. In one embodiment, the component contained in POME that inhibits the hydrogenation reaction includes an alkaline earth metal, such as at least one of Ca and Ba. In one embodiment, the component contained in POME that inhibits the hydrogenation reaction includes a metalloid or nonmetal, such as at least one of B and P. In one embodiment, the component contained in POME that inhibits the hydrogenation reaction includes 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 components that inhibit the hydrogenation reaction contained in POME may be contained alone or in combination of two or more.

[0031] 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.

[0032] 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.

[0033] (Adsorbent) The adsorbent has a function of removing components contained in POME that inhibit the hydrogenation reaction by adsorbing them.

[0034] 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.

[0035] 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.).

[0036] 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 components contained in POME that inhibit the hydrogenation reaction.

[0037] 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.

[0038] 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 POME.

[0039] (Contact) The contact method between POME and the adsorbent is not particularly limited. For example, when POME is liquid, it is preferable to add the adsorbent to POME and mix them. Furthermore, when POME is a dry product, it is preferable to dilute POME with water, add the adsorbent, and mix them, from the viewpoint of increasing the contact efficiency.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] After the contact, the adsorbent is removed by centrifugation, filtration, or the like, and then the mixture is dried to obtain purified POME.

[0045] [Degumming step] The purification step may further include a degumming step. If the purification step for POME is only a degumming step, the hydrogenation efficiency may decrease. On the other hand, if the purification step for POME includes an adsorption step, the degumming step can be suitably used in combination.

[0046] The degumming process is a process for hydrating and removing gums, the main component of which is phospholipids, contained in POME. The degumming process is not limited, but can be carried out, for example, by adding steam or water to POME, stirring, 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.

[0047] [Deodorization Step] The purification step may further include a deodorization step, which is a step for removing odorous components contained in POME. The deodorization step is not limited, but can be carried out, for example, by steam distillation under reduced pressure.

[0048] The order of the adsorption step, degumming step, and deodorizing step in the purification 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.

[0049] [Purified POME] The purified POME has been purified in a purification step to remove impurities, preferably components contained in the POME that inhibit the hydrogenation reaction, and therefore the subsequent hydrogenation step can be carried out efficiently.

[0050] <(b) Hydrogenation Step> The hydrogenation step is a step of hydrogenating the purified POME. This step results in the reduction of unsaturated groups (double bonds) in glycerides, fatty acids, etc., the production of fatty acids by decomposition of glycerides, and the production of linear saturated hydrocarbons by reduction, decarbonation, or decarboxylation of fatty acids. This allows the production of linear saturated hydrocarbons useful for biofuels from POME.

[0051] [Purified POME] The purified POME that can be used is the POME purified by the above-described purification step.

[0052] [Hydrogenation Treatment] The hydrogenation treatment is preferably carried out by adding hydrogen in an amount sufficient to saturate the unsaturated components in the purified POME.

[0053] The hydrotreatment is preferably carried out in the presence of a catalyst.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] The promoter can be supported on the catalyst carrier by impregnation, similarly to the catalytic metal.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The hydrotreating can be carried out in the presence or absence of a solvent.

[0067] When a solvent is used, any solvent commonly used in hydrogenation reactions can be used. For example, ５ ~C １２ 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 ６Examples 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] [Biofuel] Biofuel can be obtained by the hydrogenation process, which is hydrogenated vegetable oil (HVO).

[0074] The biofuel obtained by the hydrogenation step contains linear saturated hydrocarbons and may further contain unreacted substances such as glycerides and fatty acids, and by-products such as propanol and linear unsaturated hydrocarbons.

[0075] The linear saturated hydrocarbons are 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 remains unchanged or decreases by one after the hydrogenation reaction.

[0076] 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.

[0077] The biofuel obtained by the hydrogenation process can be used as hydrogenated vegetable oil (HVO) in its original form or in a form mixed with other fuels, additives, etc. Furthermore, by adjusting the carbon number of the hydrogenated vegetable oil (HVO), it can be used as sustainable aviation fuel (SAF). That is, in one embodiment, the biofuel is selected from the group consisting of hydrogenated vegetable oil (HVO) and sustainable aviation fuel (SAF).

[0078] If the biofuel is a sustainable aviation fuel (SAF), it is processed to meet SAF specifications by isomerization / hydrocracking, as described below.

[0079] <(c) Isomerization / Hydrocracking Step> The isomerization / hydrocracking step is a step of isomerizing or hydrocracking the hydrocarbons obtained in the hydrogenation step. This makes it possible to produce a biofuel that meets the standards for sustainable aviation fuel (SAF). That is, in one embodiment, the biofuel is sustainable aviation fuel (SAF), and the method for producing a biofuel further includes (c) an isomerization / hydrocracking step of isomerizing or hydrocracking the hydrocarbons obtained in the hydrogenation step.

[0080] 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.

[0081] 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.

[0082] 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 O ３ , Pt / ZSM-23 / Al ２ O ３ , and Pt / SAPO-11 / SiO ２ etc.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] Biofuels Biofuels can be obtained by the isomerization / hydrocracking process, which is sustainable aviation fuel (SAF).

[0087] The biofuel obtained by the isomerization / hydrocracking process contains paraffins and isoparaffins. It may also contain other raw material-derived components such as glycerides, fatty acids, propanol, and linear unsaturated hydrocarbons. The biofuel may also contain other fuels, additives, and the like, as needed.

[0088] 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.

[0089] 2. Method for Improving Hydrogenation Efficiency in Hydrotreating POME According to one aspect of the present invention, there is provided a method for improving the hydrogenation efficiency in the hydrotreating of palm oil mill effluent (POME). The method includes: (a) a POME purification step, which includes an adsorption step of contacting POME with an adsorbent; and (b) a hydrogenation step of hydrotreating the purified POME. In this case, the POME purification step may further include a degumming step and a deodorizing step. Steps (a) and (b), the degumming step, and the deodorizing step have been described above, and therefore will not be described again here.

[0090] 3. Method for Producing Refined POME for Use in Biofuel Production According to one aspect of the present invention, there is provided a method for producing refined palm oil mill effluent (POME) for use in biofuel production. The biofuel is produced by hydrotreating the refined POME. The method includes (a) a POME purification step, which includes an adsorption step of contacting the POME with an adsorbent. The POME purification step may further include a degumming step and a deodorizing step. The steps (a), the degumming step, and the deodorizing step have been described above, and therefore will not be described again here.

[0091] The purified POME is not particularly limited as long as it is obtained by (a) a POME purification process including an adsorption step of contacting palm oil mill effluent (POME) with an adsorbent.

[0092] In one embodiment, the purified POME may be a liquid or a dry product, but is preferably a dry product from the viewpoint of transportation costs, etc. In one embodiment, the water content of the purified 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.

[0093] In one embodiment, the refined POME contains glycerides and fatty acids, and may further contain fuel components and impurities such as palm kernel shells (PKS) and wood flour.

[0094] In one embodiment, the glyceride content in the purified POME 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.

[0095] In one embodiment, the content of fatty acids in the purified POME 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, relative to the total mass of the dried POME.

[0096] In one embodiment, the Na content in the purified POME is preferably 1.5 ppm or less, more preferably 1.1 ppm or less, and even more preferably 1 ppm or less, based on the total mass of the dried POME.

[0097] In one embodiment, the Ca content in the purified POME is preferably 15 ppm or less, more preferably 10 ppm or less, and even more preferably 6 ppm or less, based on the total mass of the dried POME. In one embodiment, the Ba content in the purified POME is preferably 0.5 ppm or less, more preferably 0.1 ppm or less, and even more preferably 0.06 ppm or less, based on the total mass of the dried POME.

[0098] In one embodiment, the purified POME has a B content of preferably 1.2 ppm or less, more preferably 0.5 ppm or less, and even more preferably 0.2 ppm or less, based on the total mass of the dried POME. In one embodiment, the purified POME has a P content of preferably 15 ppm or less, more preferably 8 ppm or less, and even more preferably 7 ppm or less, based on the total mass of the dried POME.

[0099] In one embodiment, the Cr content in the purified POME is preferably 0.1 ppm or less, more preferably 0.04 ppm or less, based on the total mass of the dried POME. In one embodiment, the Mn content in the purified POME is preferably 0.28 ppm or less, more preferably 0.25 ppm or less, and even more preferably 0.15 ppm or less, based on the total mass of the dried POME. In one embodiment, the Fe content in the purified POME is preferably 15 ppm or less, more preferably 12 ppm or less, and even more preferably 8 ppm or less, based on the total mass of the dried POME. In one embodiment, the Cu content in the purified POME is preferably 0.15 ppm or less, more preferably 0.1 ppm or less, based on the total mass of the dried POME. In one embodiment, the Zn content in the purified POME is preferably 0.22 ppm or less, more preferably 0.20 ppm or less, and even more preferably 0.15 ppm or less, based on the total mass of the dried POME. In one embodiment, the Mo content in the purified POME is preferably 0.5 ppm or less, and more preferably 0.3 ppm or less, based on the total mass of the dried POME. In one embodiment, the Cd content in the purified POME is preferably 0.35 ppm or less, more preferably 0.25 ppm or less, and even more preferably 0.2 ppm or less, based on the total mass of the dried POME.

[0100] 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.

[0101] The purified POME produced by the above-described method has a composition suitable for hydrotreating, and therefore can be suitably used for the production of biofuels.

[0102] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0103] [Production Example 1] A catalyst to be used in the hydrogenation step was prepared by the impregnation method as follows.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] Example 1 (Adsorption Step) 150 g of POME (dried product) was placed in a 300 mL three-necked flask and heated to 80° C., and then silica gel ("Sorbsil R92" manufactured by PQ Corporation) as an adsorbent was added in an amount of 2% by mass based on the POME.

[0108] Thereafter, the mixture was 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 obtain purified POME.

[0109] (Hydrogenation Step) The hydrogenation step was carried out using an autoclave as follows.

[0110] 0.15 g of the catalyst prepared in Production Example 1 was weighed into a glass reaction tube, followed by 1.0 g of purified POME. 9.0 g of cyclohexane was added. A stir bar was placed in the autoclave vessel. 2 MPa of hydrogen gas was sealed in the vessel, 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 to produce biofuel.

[0111] [Example 2] Activated clay ("Galleon Earth RS" manufactured by Mizusawa Industrial Chemicals, pH: 3, specific surface area: 330 m) was used as an adsorbent. ２ Biofuel was produced in the same manner as in Example 1, except that cellulose acetate (C10 / g) was used.

[0112] [Example 3] Activated clay ("Galleon Earth GSF" manufactured by Mizusawa Industrial Chemicals, pH: 3, specific surface area: 350 m) was used as an adsorbent. ２ Biofuel was produced in the same manner as in Example 1, except that cellulose acetate (C10 / g) was used.

[0113] Comparative Example 1 Biofuel was produced in the same manner as in Example 1, except that the adsorption step was not carried out.

[0114] Comparative Example 2 (Degumming Step) As a refining step, a degumming step using citric acid was carried out.

[0115] 138 g of POME (dried product) was placed in a 300 mL three-necked flask and heated to 80° C., and then a 30% by mass aqueous solution of citric acid was added in an amount of 0.3% by mass based on the POME.

[0116] Then, 3% by mass of distilled water was added to the POME, and the mixture was stirred for 10 minutes, followed by centrifugation at 3000 rpm for 3 minutes. The resulting upper layer was dried under reduced pressure at 60°C for 30 minutes in a three-neck flask to obtain purified POME.

[0117] (Hydrogenation Step) The hydrogenation step was carried out in the same manner as in Example 1 to produce biofuel.

[0118] [Evaluation of Biofuels] The biofuels produced in Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to composition analysis.

[0119] Specifically, 0.1 g of nonadecane was added to the biofuel as an internal standard, and gas chromatographic (GC) analysis was carried out according to the following procedure.

[0120] <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.

[0121] 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

[0122] A calibration curve was prepared for each compound to be analyzed, and the compounds were quantified using the internal standard method.

[0123] 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

[0124] 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 1 and 2.

[0125]

[0126]

[0127] The results in Tables 1 and 2 show that in Examples 1 to 3, the hydrogenation efficiency in the hydrotreating process was improved by carrying out an adsorption step using an adsorbent before the hydrogenation step.

[0128] Furthermore, in Comparative Example 2, when only the degumming step using citric acid (degumming agent) was performed, it was found that the hydrogenation efficiency in the hydrogenation treatment was reduced.

[0129] [Evaluation of POME] The impurity components in POME before the hydrogenation step were analyzed in Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, the impurity components contained in POME were analyzed by high-frequency inductively coupled plasma (ICP) atomic emission spectrometry for purified POME in Examples 1 to 3 and Comparative Example 2, and for unpurified POME in Comparative Example 1.

[0130] <ICP Atomic Emission Analysis> POME was filtered through a 0.45 μm polytetrafluoroethylene (PTFE) membrane filter, diluted with a 5-fold amount of xylene, and subjected to analysis.

[0131] 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.)

[0132] 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 diluted using refined rapeseed oil "AJINOMOTO Smooth Canola Oil" (manufactured by J Oil Mills Co., Ltd.).

[0133]

[0134] The results in Table 3 show that the impurity contents in Examples 1 to 3 are lower than in Comparative Example 1. In addition, in Comparative Example 2, when the refining process was only a degumming process, the content of some impurities was high, and it was found that components contained in POME that inhibit the hydrogenation reaction could not be removed. This is thought to be why the hydrogenation efficiency in the hydrotreating process was reduced, as shown in the results in Table 2.

Claims

1. A method for producing a biofuel, comprising: (a) a palm oil mill effluent (POME) purification step, the POME purification step including an adsorption step of contacting POME with an adsorbent; and (b) a hydrogenation step of hydrotreating the purified POME.

2. The method according to claim 1, wherein the adsorbent comprises at least one selected from the group consisting of activated clay, acid clay, silica, and activated carbon.

3. The method for producing a biofuel according to claim 1, wherein the biofuel is selected from the group consisting of hydrogenated vegetable oil (HVO) and sustainable aviation fuel (SAF).

4. The method for producing a biofuel according to claim 1, wherein the biofuel is a sustainable aviation fuel (SAF), and the production method further comprises (c) an isomerization / hydrocracking step of isomerizing or hydrocracking the hydrocarbons obtained in the hydrogenation step.

5. A method for improving hydrogenation efficiency in the hydrogenation treatment of palm oil mill effluent (POME), comprising: (a) a POME purification step including an adsorption step of contacting POME with an adsorbent; and (b) a hydrogenation step of hydrotreating the purified POME.

6. A method for producing refined palm oil mill effluent (POME) for use in the production of biofuel, comprising: (a) purifying POME, the POME comprising an adsorption step of contacting the POME with an adsorbent, wherein the biofuel is produced by hydrotreating the refined POME.