Method for resource utilization of woody biomass

Abstract

To provide a process for efficiently producing a liquid hydrocarbon using a natural resource.SOLUTION: An industrial resource utilization method for woody biomass comprises a first step of performing low-temperature hydrothermal treatment at 150°C to 280°C using woody biomass, followed by solid-liquid separation to obtain a first liquid and a first solid residue having an O / C ratio of 0.1 to 0.6, and a second step of performing high-temperature hydrothermal treatment at 280°C to 370°C using the first liquid obtained in the first step, followed by solid-liquid separation to obtain a second liquid containing a heavy oil-containing liquid and a second solid residue.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a manufacturing system for producing useful industrial products and liquid fuels using biomass, and in particular to a manufacturing method for producing char and liquid hydrocarbons. [Background technology]

[0002] The utilization of natural resources, such as biomass, is an essential technology for sustainable economic development. Previously, attempts have been made to utilize woody or herbaceous materials, primarily composed of cellulose, as natural resources to produce industrial products such as charcoal and liquid hydrocarbons.

[0003] For example, Patent Document 1 discloses a method for obtaining solid, liquid, and gaseous fuels from organic raw materials under high pressure and heating, which comprises using sediment or garbage containing microbial, plant, or animal biological material as the organic raw material, gradually heating the raw material to a conversion temperature of 200 to 600°C while blocking air, conducting the generated gas and steam through an appropriate gas separator and liquid separator, and maintaining the conversion temperature until the generation of gas and steam has substantially ceased to separate the solid conversion residue, gas, and liquid.

[0004] Furthermore, Patent Document 2 discloses a method for producing a heavy oil-like substance from microalgae, which is characterized by maintaining the microalgae at high temperature and pressure in the presence of an alkaline substance and an aqueous medium, and liquefying the microalgae into a heavy oil-like substance.

[0005] Patent Document 3 also discloses a method for hydrothermal treatment of biomass, including the steps of: introducing a biomass feedstock having a water:biomass ratio of at least 1:1 into a reaction zone, wherein the biomass feedstock has a phosphorus content; hydrothermally treating the biomass feedstock under hydrothermal treatment conditions effective to produce a multiphase product, wherein the multiphase product comprises a solid portion containing at least about 80% of the phosphorus content of the biomass feedstock; and separating the multiphase product to produce at least a gas phase portion, a liquid hydrocarbon product, and the solid portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 57-111380 A (claims, examples, etc.) [Patent Document 2] JP-A-6-41545 (claims, examples, etc.) [Patent Document 3] Patent No. 5694559 (Claims, Examples, etc.) Summary of the Invention [Problem to be solved by the invention]

[0007] The industrial use of biomass as an organic raw material requires productivity. The present inventors focused on woody biomass, a representative example of such an organic raw material, and aimed to develop a process for producing liquid hydrocarbons and charcoal using this biomass.

[0008] After detailed investigation, the inventors have found that when the hydrothermal treatment step is carried out at a low temperature using woody biomass, a solid residue containing mainly organic matter is obtained, whereas when the hydrothermal treatment step is carried out at a high temperature, mainly liquid hydrocarbons are obtained, but the overall yield from the raw biomass is low, which is industrially disadvantageous.

[0009] The problem to be solved by the present invention is to provide a process for efficiently producing liquid hydrocarbons using woody biomass. [Means for solving the problem]

[0010] After detailed investigation, the inventors discovered that when heat treating woody biomass, a liquid containing heavy oil can be efficiently obtained by heating in two stages: low-temperature hydrothermal treatment at 150°C to 280°C and high-temperature hydrothermal treatment at 280°C to 370°C, and thus arrived at the present invention.

[0011] The present invention provides a method for producing a biomass-based biomass-based biomass mixture, comprising: a first step of performing low-temperature hydrothermal treatment at 150°C to 280°C, followed by solid-liquid separation to obtain a first liquid material and a first solid residue having an O / C ratio of 0.1 to 0.6; The present invention relates to a method for converting woody biomass into an industrial resource, which comprises a second step of performing high-temperature hydrothermal treatment at 280°C to 370°C using a first aqueous phase obtained from the first liquid material obtained in the first step, followed by solid-liquid separation to obtain a second liquid material containing a heavy oil-containing liquid material and a second solid residue.

[0012] Another aspect of the present invention is a method for converting woody biomass into an industrial resource, which includes, in addition to the first and second steps, a third step in which the first solid residue and / or the second solid residue is subjected to high-temperature heat treatment at 400°C to 1000°C to co-produce a carbonized product in high yield in addition to a heavy oil-rich liquid. [Effects of the Invention]

[0013] The present invention provides a process for efficiently producing useful liquid hydrocarbons and charcoal using woody biomass. The obtained liquid hydrocarbons can be suitably used as raw materials for carbon black, tar, pitch, fuel oil for various combustion furnaces, etc. The obtained charcoal can be suitably used for activated carbon, etc. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a conceptual diagram illustrating an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] In the present invention, the woody biomass used as a raw material is not particularly limited as long as it is a wood resource, and examples thereof include waste wood, felled wood, sawdust, thinned wood, wood chips, bark, forest residues, unused trees, etc. The woody biomass may consist of one type of wood resource or may consist of multiple types of wood resources. In the present invention, it is particularly preferable to use cellulosic resources such as woody materials, for example, broad-leaved trees, coniferous trees, and herbaceous materials.

[0016] The first step includes a step of performing low-temperature hydrothermal treatment at 150°C to 280°C using woody biomass, followed by a step of separating and obtaining a first oil phase, a first aqueous phase, and a first solid residue from the treatment product.

[0017] The low-temperature hydrothermal treatment is carried out by heating the woody biomass in a treatment tank to a temperature of 150°C to 280°C, preferably 170°C to 275°C, and more preferably 190°C to 270°C. If the treatment temperature in the low-temperature hydrothermal treatment step is less than 150°C, the hydrolysis reaction will not proceed, which is not preferable, and if it exceeds 280°C, the carbonization reaction in the solid residue will proceed too quickly.

[0018] The amount of water added to woody biomass is preferably 1 to 10 times, and more preferably 2 to 10 times, the weight of the woody biomass in a dry state. The atmosphere in the treatment tank is preferably an inert gas. The pressure varies depending on the treatment temperature, but it is preferable to operate at a pressure equal to or higher than the saturated vapor pressure at the treatment temperature.

[0019] The treatment method may be a batch method or a flow method as long as the above treatment conditions are ensured, and the treatment vessel used is preferably a pressure vessel equipped with a heater and a mixer.

[0020] The treatment time is preferably 3 to 120 minutes, more preferably 5 to 60 minutes, in either the batch method or the flow method.

[0021] The product of the low-temperature hydrothermal treatment is mainly a mixture of a liquid and a solid. In the present invention, the liquid produced by the low-temperature hydrothermal treatment is referred to as a first liquid, and the solid produced is referred to as a first solid residue. In addition, a small amount of flammable gas may be produced.

[0022] The product of the low-temperature hydrothermal treatment is subjected to a conventional solid-liquid separation procedure such as decantation, filtration, or centrifugation to obtain a first liquid matter and a first solid residue. The first solid residue is a solid matter having an O / C ratio of 0.1 to 0.6, preferably 0.2 to 0.5, where the O / C ratio is the ratio of the number of oxygen atoms to the number of carbon atoms contained in the solid residue.

[0023] An O / C ratio of less than 0.1 is not preferable because the decomposition of organic matter proceeds too quickly, reducing the yield of carbonized material, while an O / C ratio of more than 0.6 is not preferable because the decomposition of organic matter does not proceed quickly, reducing the yield of liquid material.

[0024] The first solid residue is a precursor of char and is used as the raw material for the third step described below to produce char. The first solid residue is in a semi-carbonized state, with a portion of it being carbonized. Hydrothermal treatment of the raw wood biomass promotes a hydrolysis reaction, so the O / C ratio of the first solid residue is lower than that of the raw wood biomass.

[0025] The first liquid consists of an aqueous phase containing water-soluble substances and an organic phase containing organic solvent-soluble substances, and is sent to the second step as is, or the aqueous phase alone is collected as the first aqueous phase by oil-water separation. The first liquid can also be subjected to oil-water separation to separate the organic phase containing organic solvent-soluble substances from the aqueous phase containing water-soluble substances, and this can be combined with the heavy oil-containing liquid described below.

[0026] The second step includes a step of performing a high-temperature hydrothermal treatment at 280°C to 370°C, followed by a step of separating and obtaining a second oil phase, a second aqueous phase, and a second solid residue from the treatment product.

[0027] The high-temperature hydrothermal treatment is carried out by heating the first aqueous phase in a treatment tank to a temperature of 280°C to 370°C, preferably 290°C to 360°C, and more preferably 300°C to 350°C.

[0028] If the treatment temperature in the high-temperature hydrothermal treatment step is less than 280°C, the heavy oil yield will decrease because the heavy oil conversion reaction will not proceed smoothly, and if it exceeds 370°C, the decomposition of organic matter and the carbonization reaction will proceed too quickly, reducing the yield of the liquid material.

[0029] The atmosphere in the treatment tank is preferably an inert gas, and the pressure is preferably in the range of 2.5 MPa to 22 MPa, although this depends on the treatment temperature.

[0030] The treatment method may be a batch or flow type as long as the above treatment conditions are ensured, and the treatment tank used is preferably a pressure vessel equipped with a heater and a mixer. In either the batch or flow type, the treatment time is preferably 3 to 60 minutes, more preferably 5 to 30 minutes.

[0031] The product of the high-temperature hydrothermal treatment is primarily a mixture of liquid and solid matter. In the present invention, the liquid produced by the high-temperature hydrothermal treatment is referred to as a second liquid matter, and the solid matter produced is referred to as a second solid residue. In addition, decomposition gas is produced, the majority of which is CO2, which can be captured with calcium hydroxide and recovered as calcium carbonate.

[0032] The product of the high-temperature hydrothermal treatment is subjected to a conventional solid-liquid separation procedure such as decantation, filtration, or centrifugation to obtain a second liquid and a second solid residue.

[0033] The second solid residue is a precursor of a char and is used as a raw material for producing a char when subjected to the third step described below. The second solid residue is in a semi-carbonized state, where a portion of the residue is carbonized. By subjecting the raw wood biomass to hydrothermal treatment, hydrolysis and carbonization reactions proceed, so the second solid residue usually has a lower O / C ratio than the raw wood biomass.

[0034] The second liquid is composed of a second aqueous phase containing water-soluble organic matter and a second oil phase containing organic solvent-soluble matter, and is separated by a separation operation to obtain the second aqueous phase and the second oil phase.

[0035] The second oil phase obtained in the second step can be purified and separated into useful carbon-containing components such as light oil, heavy oil, pitch, and tar by a refining step such as distillation, and can be used as chemicals, fuels, or other industrial products. The first oil phase separated by the oil-water separation operation in the first step can also be used as a raw material in the refining step.

[0036] The main components of woody biomass are cellulose, hemicellulose, and lignin. By supplying woody biomass as a raw material to the first step, the cellulose and hemicellulose are primarily hydrolyzed, producing a water-soluble mixture consisting primarily of water-soluble low-molecular-weight compounds and / or oligomers. Examples of water-soluble mixtures include sugars and lignophenols. By supplying the first liquid material obtained through the first step to the second step, a significant amount of the water-soluble organic matter in the first liquid material becomes heavier and turns into organic solvent-soluble matter. Furthermore, at least a portion of the organic solvent-soluble matter in the first liquid material becomes even heavier, increasing the yield of carbonized material.

[0037] Here, in order to efficiently advance the industrial recycling of woody biomass, it is essential to combine the first and second steps. If the first step is not carried out, decomposition will proceed too far in the high-temperature hydrothermal treatment, resulting in less organic matter in the solid residue and a low carbonized product yield. Furthermore, if the second step is not carried out, the decomposition of woody biomass will not proceed sufficiently, and subsequent heavy oil conversion will be difficult, resulting in a low heavy oil content and the inability to produce organic solvent-soluble materials with a high yield.

[0038] The second aqueous phase obtained in the second step is preferably subjected to a fermentation step. In the fermentation step, the water-soluble organic matter contained in the second aqueous phase is fermented by microorganisms to obtain a combustible gas containing methane. The obtained combustible gas can be used as a fuel gas. Carbon dioxide produced as a by-product in the fermentation step can be reacted with lime to produce calcium carbonate.

[0039] The solid residue obtained in the first step and / or the second step can be supplied to the third step described below to co-produce a charcoal. A preferred embodiment of the present invention includes a third step in which the first solid residue obtained in the first step and / or the second solid residue obtained in the second step are subjected to high-temperature treatment to obtain a charcoal.

[0040] The high-temperature heat treatment in the third step can be carried out depending on the application, and is usually carried out by heating at a temperature in the range of 400°C to 1000°C in an oxygen-free state.

[0041] If the temperature of the high-temperature heat treatment in the third step is in the range of 400°C to 1000°C, the decomposition of organic matter proceeds, fewer remaining elements are left, and the quality of the carbonized product is excellent.Furthermore, there is no need to treat at unnecessarily high temperatures, and energy efficiency is good, so this is preferable.During the high-temperature treatment, the atmosphere in the treatment tank is preferably an inert gas.The pressure is preferably in the range of normal pressure to 1 MPa.

[0042] The time for the high-temperature treatment is preferably 20 to 120 minutes, more preferably 30 to 90 minutes. The treatment method may be a batch method or a flow method as long as the above treatment conditions are ensured, and the treatment vessel used is preferably a combustion furnace or an electric furnace.

[0043] The O / C ratio of the carbide obtained by the third step is preferably 0 to 0.2, more preferably 0 to 0.1. The physical properties of the carbide can be controlled by managing the temperature and time of the high-temperature heat treatment step. The carbide obtained can be suitably used as a raw material for carbides such as activated carbon. According to the present invention described above, it is possible to obtain carbon-containing components in an industrially usable form from organic components contained in raw wood biomass. [Example]

[0044] In the following Examples and Comparative Examples, each of the components produced was measured according to JIS M-8819 Coals and cokes - Elemental analysis using an instrumental analyzer and JIS M-8813 Coals and cokes - Elemental analysis.

[0045] Example 1 (first step) One gram of dry wood flour (cedar wood) was crushed and mixed with water at a weight ratio of dry wood flour / water = 1 / 4, and then subjected to hydrothermal treatment at 250°C for 10 minutes in a 9 mL SUS pressure-resistant container (autoclave). At this time, the pressure inside the autoclave was controlled at 5 MPa or less.

[0046] The reaction mixture after the hydrothermal treatment was washed with THF and water, filtered, and the solid matter was filtered and dried to obtain a solid residue (first solid residue). The filtrate was separated into oil and water, and the THF was removed from the oil layer to obtain the solvent-soluble matter. The water layer was left as it was to obtain the water-soluble matter. The solvent-soluble matter and water-soluble matter were combined to obtain a first liquid matter.

[0047] The carbon yield of each component in the first step, based on the dry wood flour raw material (100%), was 1.2% for the gas component, 23.3% for the water-soluble component of the first liquid, 11.6% for the solvent-soluble component of the first liquid, and 64.0% for the first solid residue. The O / C and H / C ratios of the first solid residue were 0.40 and 1.30, respectively. The O / C and H / C ratios of the solvent-soluble component of the first liquid were 0.13 and 1.50, respectively.

[0048] (Second process) The water-soluble matter (0.15 g as carbon) obtained in the first step was subjected to hydrothermal treatment in a 9 mL SUS pressure-resistant vessel (autoclave) at 350° C. for 5 minutes, while the pressure inside the autoclave was controlled to 20 MPa or less.

[0049] The reaction mixture after the hydrothermal treatment was washed with THF and water, filtered, and the solid matter was filtered and dried to obtain a solid residue (second solid residue). The filtrate was separated into oil and water, and the THF was removed from the oil layer to obtain the solvent-soluble matter. The aqueous layer was left as the water-soluble matter. The solvent-soluble matter and water-soluble matter were combined to obtain a second liquid.

[0050] The carbon yield of each component in the second step, with the water-soluble component obtained in the first step taken as 100%, was 11.2% for the gas component, 49.4% for the water-soluble component of the second liquid, 33.3% for the solvent-soluble component of the second liquid, and 6.2% for the second solid residue. The O / C and H / C ratios of the second solid residue were 0.4 and 0.7, respectively. The O / C and H / C ratios of the solvent-soluble component of the second liquid were 0.1 and 1.1, respectively. In addition, the total carbon yield of each component obtained in the first and second steps, with the raw material dry wood flour being 100%, was 3.8% for gas components, 11.5% for water-soluble components in the liquid, 19.4% for solvent-soluble components in the liquid, and 65.4% for solid residue.

[0051] (Third step) The first solid residue and the second solid residue (total 10 g) were subjected to high-temperature treatment (carbonization treatment) in an electric furnace under air atmosphere at 1000°C for 1 hour to obtain 3.5 g of charcoal. The O / C ratio and H / C ratio of the charcoal obtained in the third step were 0.02 and 0.08, respectively.

[0052] Comparative Example 1 1 g of dried wood powder (cedar wood) and 7 mL of water were placed in a 9 mL 1 / 2-inch stainless steel reaction tube and heated in a salt bath at 230°C for 5 minutes, after which the reaction tube was removed and quenched in water.

[0053] After the hydrothermal treatment, the gas fraction, solid residue, oil phase, and aqueous phase were recovered in the same manner as in the first step of Example 2.

[0054] The carbon yield of each component, calculated based on the dry wood powder raw material as 100%, was 1.2% for gas components, 28.3% for water solubles, 8.5% for solvent solubles, and 62% for solid residue. Although the solid residue was high, the solvent solubles were low, resulting in a low yield of heavy oil. [Industrial Applicability]

[0055] According to the present invention, there is provided a process for efficiently producing useful liquid hydrocarbons, preferably liquid hydrocarbons and charcoal, using woody biomass, which is a type of biomass.

Claims

1. The method for recycling woody biomass comprises: a first step of performing low-temperature hydrothermal treatment at 150°C to 280°C using woody biomass, followed by solid-liquid separation to obtain a first liquid material and a first solid residue having an O / C ratio of 0.1 to 0.6; and a second step of performing high-temperature hydrothermal treatment at 280°C to 370°C using the first liquid material obtained in the first step, followed by solid-liquid separation to obtain a second liquid material containing a heavy oil-containing liquid material and a second solid residue.

2. The method according to claim 1, further comprising a third step of performing a high-temperature heat treatment at 400°C to 1000°C using the first solid residue and / or the second solid residue to obtain a carbide.

3. 2. The method of claim 1, wherein the carbonized material obtained in the third step is activated carbon.

4. The method according to claim 1, wherein the second liquid obtained in the second step is subjected to liquid-liquid separation to obtain a heavy oil-containing liquid consisting of light oil, heavy oil, pitch, tar, or a mixture of two or more thereof, and an aqueous phase.

5. The method according to claim 1, wherein the aqueous phase obtained in the second step is subjected to a fermentation step in which the aqueous phase is fermented by a microorganism to obtain a combustible gas containing methane.

Images