Method for producing microcrystalline cellulose (MCC) from biomass

Abstract

Provided is a method for producing microcrystalline cellulose (MCC) from biomass, the method comprising the steps of: (1) removing hemicellulose from classified biomass; (2) removing lignin from the product obtained in step (1); (3) bleaching the product obtained in step (2); (4) depolymerizing the product obtained in step (3) to prepare microcrystalline cellulose (MCC); (5) neutralizing the product in step (4); and (6) spray drying a solution containing the product in step (5) to obtain a microcrystalline cellulose (MCC) powder satisfying a predetermined size condition.

Description

Method for producing microcrystalline cellulose (MCC) from biomass

[0001] The present invention relates to a method for producing microcrystalline cellulose (MCC) from biomass, and more particularly, to a method for producing microcrystalline cellulose (MCC) useful for pharmaceuticals, foods, cosmetics, etc. from biomass using a closed-loop selective separation technology.

[0002] Biomass typically includes woody materials such as rice straw, wheat straw, wheat bran, onion hulls, pear peels, and twigs, as well as agricultural byproducts and brewing byproducts. This biomass contains cellulose (30–50 wt%), hemicellulose (20–35 wt%), lignin (10–25 wt%), and silica (1–15 wt%).

[0003] Cellulose, the primary structural component of plant cell walls, consists of glucose chains linked by β-1,4 glycosidic bonds. These cellulose chains form microfibrils through van der Waals and hydrogen bonds. These microfibrils are surrounded by lignin and hemicellulose. The process of converting lignocellulosic resources into biofuels and bioproducts involves decomposing and hydrolyzing the raw material and separating its various components. For example, the bioconversion process, which converts lignocellulosic materials into biofuels such as ethanol, involves four fundamental steps: pretreatment, enzymatic hydrolysis, fermentation, and product recovery.

[0004] Furthermore, established protocols exist for extracting components from biomass feedstocks. These processes always begin with a pretreatment step, which serves to reduce the dimensions of the biomass and increase the accessible surface area for subsequent processing. Pretreatment significantly influences the efficiency and economics of bioconversion processes. For this purpose, various techniques have been developed, including mechanical force, steam, acids, alkalis, biological agents, or combinations thereof. Several prior art inventions have focused on mechanical (grinding, extrusion, milling, and shredding), thermal (steam explosion and autohydrolysis), and chemical (acid and alkali treatment) methods for biomass valorization.

[0005] Typically, harvested residues such as rice straw and wheat straw in cultivated fields are incinerated or composted. Efforts are being made to promote sustainability by valuing crop residues, which are wood-based chemical compounds. The present invention utilizes microcrystalline cellulose as a value-added product with minimal chemical and energy input, eliminating the need for sequential removal of crop residue components to extract the cellulose fraction. This can dramatically reduce the burden on existing wood-based biomass resources.

[0006] Microcrystalline cellulose (MCC) is a material that can be derived from this biomass. Due to its diverse properties, MCC is essential in the pharmaceutical, cosmetic, food, and packaging industries. In the pharmaceutical field, it functions as an excipient, improving tablet stability and aiding in the regulated release of drugs. It also maintains the uniformity and organoleptic properties of cosmetic products. Furthermore, MCC is used in the food industry as a texturizing and anti-baking agent, enhancing the texture of food products and reducing lump formation.

[0007] However, the conventional manufacturing process of microcrystalline cellulose has several technical problems in controlling the crystal structure, managing the formation of aggregates, and maintaining a consistent particle size distribution.

[0008] In other words, particle size uniformity is a critical factor affecting the material's efficacy across a wide range of applications. Controlling the cellulose crystal structure requires maintaining the desired polymorphic state throughout the process. Furthermore, efficiently converting cellulose into a microcrystalline form while minimizing energy consumption and environmental impact presents significant challenges in optimizing the hydrolysis process. Preventing the formation of aggregates, which can impair the fluidity and compressibility of the final product, is also a significant challenge.

[0009] Conventional methods for producing microcrystalline cellulose often rely on wood-based feedstocks, contributing to deforestation and other environmental problems. Especially when mechanically processing cellulose fibers, the production of microcrystalline cellulose often involves energy-intensive processes. Furthermore, converting cellulose into a microcrystalline structure requires careful optimization of chemical treatments, often involving acid hydrolysis. Therefore, optimization of reaction conditions is necessary to achieve high yields and purity while minimizing degradation and waste.

[0010] Furthermore, for microcrystalline cellulose to be effectively used in fields such as pharmaceuticals and foods, its physical properties, such as flowability, compressibility, and moisture content, must be maintained consistently, and managing these properties during the production process is also challenging. Furthermore, the microcrystalline cellulose manufacturing process often involves multiple steps, such as feedstock processing, chemical treatment, and purification. Each step can require significant water input, resulting in high water usage. Furthermore, the production of microcrystalline cellulose consumes significant amounts of energy, including electricity for heating, stirring, filtration, and drying. The energy required throughout the MCC process makes it an energy-intensive process.

[0011] Accordingly, the present invention provides a method for producing a new microcrystalline cellulose (MCC) that can solve the above-described problems in the microcrystalline cellulose manufacturing process.

[0012] In order to solve the above problem, the present invention provides a method for producing microcrystalline cellulose (MCC) from biomass, comprising the steps of: (1) removing hemicellulose from classified biomass; (2) removing lignin from the product obtained from step (1); (3) bleaching the product obtained from step (2); (4) depolymerizing the product obtained from step (3) to obtain microcrystalline cellulose (MCC); (5) neutralizing the product of step (4); and (6) spray drying a solution containing the product of step (5) to obtain microcrystalline cellulose (MCC) powder satisfying a predetermined size condition.

[0013] In one embodiment of the present invention, the order of steps (3) and (4) may be changed, and between steps (1) and (2), between steps (2) and (3), between steps (3) and (4), between steps (4) and (5), and between steps (5) and (6), a step of washing and filtering the product of each step may be further included.

[0014] In one embodiment of the present invention, the wastewater generated after the washing is recovered and treated through a single molar reuse system.

[0015] In one embodiment of the present invention, the molar reuse system includes anaerobic membrane bioreactors (AnMBRs) that convert organic matter in the wastewater into methane, and water in which organic matter is converted into methane by the anaerobic membrane bioreactors (AnMBRs) is reused in the washing step of the method for producing microcrystalline cellulose (MCC) according to claim 3.

[0016] In one embodiment of the present invention, the converted methane is utilized as an energy source and used in the method for producing microcrystalline cellulose (MCC).

[0017] In one embodiment of the present invention, step (2) is performed by treating with 8% NaOH (w / v) at 120°C for 1.5 hours in a closed reactor (1 barg), and step (3) is performed by bleaching with 2-4% H2O2 at pH 11.0-11.5 and 50°C for 2 hours.

[0018] In one embodiment of the present invention, the step (4) is carried out by hydrolysis under acid conditions.

[0019] The method according to the present invention is applicable to various types of biomass and has the advantage of minimizing the use of chemicals at low cost, thereby minimizing environmental impact. Furthermore, by optimizing particle size for efficient reaction through a 40-mesh biomass fraction, it leads to low consumption of small amounts of chemicals.

[0020] In addition, the economic feasibility of MCC production has been improved by using a system that recovers energy from wastewater generated at each process stage and reuses water. In particular, by introducing a closed-loop energy and water recovery system, energy usage has been reduced by 10%, and 70% of the treated water is reused. This efficiency is expected to lead to a significant cost reduction of 10-15% in the total operating cost, including the cost of treating the wastewater stream.

[0021] Figure 1 is a step diagram of a method for producing microcrystalline cellulose (MCC) according to one embodiment of the present invention.

[0022] Figure 2 is a step diagram of a method for producing microcrystalline cellulose according to Example 1.

[0023] Figure 3 is a step diagram of a method for producing microcrystalline cellulose according to Example 2.

[0024] Figure 4 is a step diagram of a water recycling method according to one embodiment of the present invention.

[0025] FIG. 5 is a schematic diagram illustrating the operating principle of an anaerobic membrane bioreactor (AnMBR) according to one embodiment of the present invention.

[0026] Figure 6 is a Fourier transform infrared of a microcrystalline cellulose sample produced according to the present invention.

[0027] Figure 7 is an X-ray diffraction (XRD) diagram of a microcrystalline cellulose sample produced according to the present invention.

[0028] Figure 8 shows the thermogravimetric analysis (TGA) results of a fine crystalline cellulose sample.

[0029] Figure 9 is a field emission scanning electron microscope (FE-SEM) image of a microcrystalline cellulose sample produced according to the present invention.

[0030] Figure 10 shows the results of measuring the recovered MCC size according to the classification of biomass using the dynamic light scattering (DLS) method.

[0031] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0032] Before describing the present invention in detail, it should be noted that the terms or words used in this specification should not be interpreted as being unconditionally limited to their usual or dictionary meanings, and the inventor of the present invention may appropriately define and use the concepts of various terms in order to describe his or her invention in the best possible manner.

[0033] Furthermore, it should be noted that these terms and words should be interpreted with meanings and concepts that are consistent with the technical idea of ​​the present invention.

[0034] That is, the terms used in this specification are only used to describe preferred embodiments of the present invention, and are not intended to specifically limit the contents of the present invention.

[0035] It should be noted that these terms are defined taking into account the various possibilities of the present invention.

[0036] Additionally, in this specification, a singular expression may include a plural expression unless the context clearly indicates a different meaning.

[0037] Also, it should be noted that even if similarly expressed in plural, it can contain singular meaning.

[0038] Throughout this specification, whenever a component is described as "including" another component, it may mean that the component may further include any other component, rather than excluding any other component, unless specifically stated otherwise.

[0039] Furthermore, if a component is described as being "internal to, connected to, or installed within" another component, it is understood that the component may be directly connected to, or installed in contact with, the other component.

[0040] In order to solve the above-described problem, the present invention provides a method for effectively producing microcrystalline cellulose (MCC) while reducing environmental impact by utilizing feedstock not extracted from wood, and the process steps for this include drying, crushing, classifying, removing hemicellulose, delignification, depolymerization, separation, bleaching, and powder drying of biomass.

[0041] The method of the present invention enables quantitative recovery of microcrystalline cellulose at low cost, and optimizes particle size by fractionating biomass with a 40 mesh size, thereby reducing chemical consumption in subsequent processing steps. Furthermore, 95% hemicellulose recovery and 90% lignin removal are possible, with 70% of microcrystalline cellulose (MCC) obtained through hemicellulose and alkaline lignin recovery. Furthermore, water washing improves product quality at each process step, and post-bleaching depolymerization enables the production of high-quality cellulose free of pigments and lignin.

[0042] Figure 1 is a step diagram of a method for producing microcrystalline cellulose (MCC) according to one embodiment of the present invention.

[0043] Referring to FIG. 1, a method for producing microcrystalline cellulose (MCC) according to one embodiment of the present invention includes: (1) a step of removing hemicellulose from classified biomass (Hemicellulose removal); (2) a step of removing lignin from the product obtained from step (1) (Delignification); (3) a step of bleaching the product obtained from step (2) (Bleaching); (4) a step of depolymerizing the product obtained from step (3) to obtain microcrystalline cellulose (MCC) (Depolymerization); (5) a step of neutralizing the product of step (4) (Neutralization); and (6) a step of spray drying a solution containing the product of step (5) to obtain microcrystalline cellulose (MCC) powder satisfying a predetermined size condition (Spray drying).

[0044] The present invention specifically washes and filters the step-by-step product between each step, and integrates and treats the wastewater generated during the process into a single wastewater treatment system (water reuse system), converting dissolved organic substances during the treatment into methane, which is then utilized for energy recovery, and thereafter, the treated wastewater and recovered energy are reused again in a microcrystalline cellulose (MCC) production method, thereby recycling water and energy in a closed loop manner.

[0045] The method according to the present invention reduces energy consumption by 10% and reuses 70% of treated water through the introduction of a closed loop system, an energy and water recovery system, etc., and this efficiency improvement enables a significant cost reduction of 10 to 15% in the total operating cost, including the reduction in wastewater flow treatment costs.

[0046] Furthermore, to induce an efficient chemical reaction in the hemicellulose removal step, the present invention classifies biomass to a size of 40 mesh or smaller and then introduces it into the process. The reaction efficiency is highest with the classified raw material size of 40 mesh or smaller, resulting in a uniform final product size of 25-50 microns.

[0047]

[0048] The present invention is described in more detail below through preferred embodiments and experimental examples.

[0049]

[0050] Example 1

[0051] Production of microcrystalline cellulose (MCC) from rice straw

[0052] In Example 1, microcrystalline cellulose (MCC) was produced from rice straw.

[0053] Figure 2 is a step diagram of a method for producing microcrystalline cellulose according to Example 1.

[0054] Referring to Figure 2, rice straw, a solid waste generated from rice processing, was prepared and is composed of 30-40% cellulose, 25-35% hemicellulose, 15-20% lignin, 10-12% silica, and 5-8% ash. After drying, the rice straw was pulverized and classified through 40-mesh (400 micron), and the rice straw powder was treated with pressure-mediated hydrothermal pretreatment.

[0055] At this time, the rice straw was subjected to pressurized hydrothermal treatment by adding water at a solid-to-liquid ratio of 1:15, and heated at 120°C for 90 minutes in a closed reactor (1 barg) to remove the hemicellulose fraction from the rice straw.

[0056] After filtration and washing, the pretreated lignocellulosic residual biomass was delignified and silica was removed by alkaline catalytic hydrothermal treatment, wherein the reaction step was treated with 8% NaOH (w / v) at 120°C for 1.5 hours in a closed reactor (1 barg) for delignification of the biomass.

[0057] After filtration to recover lignin, washing and filtration were performed again, and the lignin was recovered, so that the cellulose from which lignin was removed was decolorized with active oxygen species in an alkaline medium, and the bleached cellulose was depolymerized in the presence of relatively strong acid hydrolysis to produce microcrystalline cellulose in a suspension. In one embodiment of the present invention, the defatted biomass was bleached with 2-4% H2O2 at pH 11.0-11.5 and 50°C for 2 hours to bleach the cellulose pulp, and the depolymerization was performed with 2.5 N HCl at 80°C for 1 hour. Afterwards, the resulting microcrystalline cellulose suspension was separated, neutralized, washed, and spray-dried to produce a microcrystalline cellulose powder. In one embodiment of the present invention, a microcrystalline cellulose solution (2% w / v) was spray-dried to produce a microcrystalline cellulose powder having a uniform particle size (25 to 50 microns).

[0058] The present invention specifically performs water washing at each stage, and forms a closed loop in which all washed water is recovered and reused.

[0059]

[0060] Example 2

[0061] Production of microcrystalline cellulose (MCC) from brewery byproducts

[0062] In Example 2, microcrystalline cellulose (MCC) was produced from brewery byproduct, beer lees.

[0063] Figure 3 is a step diagram of a method for producing microcrystalline cellulose according to Example 2.

[0064] Referring to Figure 3, a brewing by-product, which is a solid waste generated in the brewing process and is composed of 40-45% cellulose, 28-35% hemicellulose, 15-20% lignin, and 2-4% ash, was prepared. After drying, it was ground and classified into 40-mesh (400 micron), and the powder was treated with pressure-mediated hydrothermal pretreatment.

[0065] At this time, the brewing by-product was subjected to pressurized hydrothermal treatment by adding water at a solid-to-liquid ratio of 1:15, and heated at 120°C for 90 minutes in a closed reactor (1 barg) to remove the hemicellulose fraction from the brewing by-product.

[0066] After filtration and washing, the pretreated lignocellulosic residual biomass is delignified under alkaline conditions, and the alkaline pretreated residue is washed to remove alkaline lignin from the biomass. Thereafter, a microcrystalline cellulose suspension is generated through depolymerization using mild acid hydrolysis, and the residue is decolorized by removing residual pigments from the microcrystalline cellulose and purifying it with reactive oxygen species in an alkaline medium.

[0067] In one embodiment of the present invention, delignification of biomass was carried out in a closed reactor (1 barg) at 120°C for 1.5 hours with 8% NaOH (w / v), and the defatted biomass was bleached into cellulose pulp with 2-4% H2O2 at pH 11.0-11.5 and 50°C for 2 hours, and depolymerization was carried out with 1 N HCl at 80°C for 1 hour. Unlike Example 1, in Example 2, depolymerization was carried out after bleaching, which was to obtain a clear color of the final product similar to Example 1.

[0068] Afterwards, the resulting microcrystalline cellulose suspension was separated, neutralized, washed, and spray-dried to produce a microcrystalline cellulose powder. In one embodiment of the present invention, a microcrystalline cellulose solution (2% w / v) was spray-dried to produce a microcrystalline cellulose powder having a uniform particle size (25 to 50 microns). In particular, the present invention performs water washing at each stage, and all the washed water is recovered and reused, forming a closed loop.

[0069]

[0070] Example 3

[0071] Energy and water recycling for MCC production

[0072] As described above, in the MCC production process according to the present invention, a large amount of water is generated in each of the hemicellulose removal, delignification, bleaching, depolymerization, and neutralization processes. In the present invention, wastewater generated by each MCC production process is integrated and treated.

[0073] Figure 4 is a step diagram of a water recycling method according to one embodiment of the present invention.

[0074] Referring to Figure 4, organic matter in the wastewater generated at each process step is converted into methane through anaerobic membrane bioreactors (AnMBRs) for energy recovery.

[0075] Figure 5 is a schematic diagram illustrating the operating principle of an anaerobic membrane bioreactor (AnMBR) according to one embodiment of the present invention, as disclosed in Korean Patent Publication No. 10-2016-0149700, among others. The present invention collects wastewater generated at each process stage during MCC production and processes it using an anaerobic membrane bioreactor (AnMBR) to generate methane, which is then utilized as an energy source. This can improve energy efficiency by more than 10%.

[0076] Referring to FIGS. 4 and 5, AnMBR according to one embodiment of the present invention is a technology combining anaerobic digestion and membrane filtration, in which organic substances are converted into methane through the metabolism of anaerobic microorganisms, and particles are filtered out through membrane filtration.

[0077] In the present invention, methods for increasing flux and alleviating membrane fouling, such as the type of membrane, membrane material, use of media and granules, gas sparging, and periodic chemical cleaning, are considered to improve the efficiency of the AnMBR system. For example, membrane separation may include inorganic membranes and organic membranes, such as ultrafiltration (UF), microfiltration (MF), dynamic membranes, and ceramic membranes. In addition, methods for reducing membrane fouling may include microbial granules, media, gas saving, and periodic chemical cleaning. The pH of the system was also maintained between 6.5 and 8.5, which is close to the neutral range, and a neutral pH can be maintained through an external alkaline supply.

[0078] Methane converted from organic matter by the above-described anaerobic membrane bioreactors (AnMBRs) is used as an energy source for operating the MCC production system described above. Recovery of dissolved methane using gas-permeable membranes or vacuum degassing methods is also considered.

[0079] Wastewater treated in the above AnMBRs to produce methane from organic matter is further treated using water reuse processes, including nanofiltration (NF), forward osmosis (FO), and reverse osmosis (RO). Treated water from the water reuse process is reused as water for the MCC production process, and treated water from the water reuse process is used as treated water for hemicellulose removal, delignification, bleaching, and depolymerization processes. Residual organic matter in the RO concentrate can be treated using advanced oxidation methods, such as chemical oxidation (e.g., H2O2, O3), and the salts are recovered as resources through evaporation.

[0080]

[0081] Experimental example

[0082] Figure 6 is a Fourier transform infrared spectrum of a microcrystalline cellulose sample produced according to the present invention.

[0083] Referring to Fig. 6, the molecular structure of the cellulose component was confirmed through the detection of spectral absorbance peaks located near 3330 cm-1 and 2890 cm-1 frequency regions due to the vibration of alcoholic functional groups and aliphatic CH groups. The absorbance maxima observed around 1640 cm-1, 1380 cm-1, and 1050 cm-1 were attributed to the vibrational characteristics of the glucose ring and auxiliary groups consisting of the bending vibration of -OH (alcoholic) water, the in-plane bending of the CH bond, and CC-OH and CH vibrations. In addition, the peaks located around 1160 cm-1 and 895 cm-1 were different depending on the asymmetric stretching of the ether bond and the stretching of the glycosidic bond, respectively. The spectral absorption around 1430 cm-1, which is assigned to the asymmetric bending of the methylene moiety and is considered a "crystalline band", indicating the presence of more crystalline regions.

[0084] Figure 7 is an X-ray diffraction (XRD) diagram of a microcrystalline cellulose sample produced according to the present invention.

[0085] Referring to Fig. 7, the XRD analysis of the samples showed 15 of the 2θ values ​​as shown in the X-ray diffraction graphs. o , 18 o , 22 o (crystalline peak) and 35 o The presence of unique peaks near the surface was observed. Four specific crystalline planes (101, 101, 002, and 040) were identified in the sample. From the XRD plot, the percent crystallinity of the microcrystalline cellulose was calculated to be 90%. The increase in crystallinity in the sample is associated with the decrease in the corresponding amorphous domains due to the breakdown of glycosidic bonds (depolymerization) in the cellulose polymer chains.

[0086] Figure 8 shows the thermogravimetric analysis (TGA) results of a fine crystalline cellulose sample.

[0087] Referring to Figure 8, TGA showed the variation of weight loss and decomposition as a function of heating. Decomposition of the microcrystalline cellulose sample began at 300°C, and the maximum loss occurred at 400°C, corresponding to approximately 80% of the total decomposition.

[0088] Figure 9 is a field emission scanning electron microscope (FE-SEM) image of a microcrystalline cellulose sample produced according to the present invention.

[0089] Referring to Fig. 9, microcrystalline cellulose having a size of less than 25 microns can be confirmed.

[0090] Figure 10 shows the results of measuring the recovered MCC size according to the classification of biomass using the dynamic light scattering (DLS) method.

[0091] Referring to Figure 10, it can be seen that for biomass classified to 40 microns or less, the recovered MCC particles are concentrated to less than 25 microns in size. This demonstrates that when using biomass classified by the method according to the present invention, MCC particles of very uniform size can be obtained.

[0092] The present invention is for producing microcrystalline cellulose (MCC) from biomass and is recognized as having industrial applicability.

Claims

1. A method for producing microcrystalline cellulose (MCC) from biomass, (1) A step of removing hemicellulose from classified biomass; (2) A step of removing lignin from the product obtained from the above step (1); (3) A step of bleaching the product obtained from the above step (2); (4) A step of depolymerizing the product obtained from the above step (3) to obtain microcrystalline cellulose (MCC); (5) a step of neutralizing the product in step (4); and (6) A method for producing microcrystalline cellulose (MCC) from biomass, comprising a step of spray drying a solution containing the product of step (5) to obtain microcrystalline cellulose (MCC) powder satisfying a predetermined size condition.

2. In paragraph 1, A method for producing microcrystalline cellulose (MCC), characterized in that the order of steps (3) and (4) above is reversed.

3. In paragraph 1, the method for producing microcrystalline cellulose (MCC) from biomass is as follows: A method for producing microcrystalline cellulose (MCC), characterized in that it further comprises a step of washing and filtering the product of each step between steps (1) and (2), steps (2) and (3), steps (3) and (4), steps (4) and (5), and steps (5) and (6).

4. In paragraph 3, A method for producing microcrystalline cellulose (MCC), characterized in that the wastewater generated after the above washing is recovered and treated through a single molar reuse system.

5. In the fourth paragraph, the molten metal recycling system, It includes anaerobic membrane bioreactors (AnMBRs) that convert organic matter in the wastewater into methane, A method for producing microcrystalline cellulose (MCC), characterized in that water in which organic matter is converted into methane by the above anaerobic membrane bioreactors (AnMBRs) is reused in the washing step of the method for producing microcrystalline cellulose (MCC) according to claim 3.

6. In paragraph 5, A method for producing microcrystalline cellulose (MCC), characterized in that the converted methane is utilized as an energy source and used in the method for producing microcrystalline cellulose (MCC).

7. In paragraph 1, A method for producing microcrystalline cellulose (MCC), characterized in that the above step (2) is performed in a closed reactor (1 barg) at 120°C for 1.5 hours with 8% NaOH (w / v).

8. In paragraph 1, A method for producing microcrystalline cellulose (MCC), characterized in that the above step (3) is performed by bleaching with 2-4% H2O2 at pH 11.0-11.5 and 50°C for 2 hours.

9. In paragraph 1, A method for producing microcrystalline cellulose (MCC), characterized in that the above step (4) proceeds through hydrolysis under acid conditions.

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