Reaction apparatus and method for continuous staged extraction of biomass hemicellulose

Abstract

The present application relates to a kind of reaction device and method applied to the continuous stage extraction of hemicellulose of biomass, the reaction device includes extractant supply system, extraction reaction system and product collection system, wherein extractant supply system mainly includes extractant storage bottle, liquid flow divider and horizontal flow pump;Extraction reaction system includes rapid heating box, thermal radiation extractant preheater, flow-through reactor, temperature and pressure detection device and extractant distribution filter device;Product collection system includes metal mesh filter, cooling tank, back pressure regulator and sample collection bottle.The reaction device can realize the step-by-step continuous extraction and collection of biomass hemicellulose under different solvent gradient, different time gradient, different temperature gradient, and significantly weaken the secondary degradation reaction of extracted hemicellulose in reaction system, retain hemicellulose macromolecular structure, improve the yield of macromolecular hemicellulose polymer, and can be used to study the extraction process and mechanism of hemicellulose.

Description

Technical Field

[0001] This invention relates to the field of biomass high-efficiency utilization technology, and more specifically to a reaction apparatus and method for continuous stepwise extraction of hemicellulose from biomass. Background Technology

[0002] Biomass is the world's most abundant renewable organic carbon resource and is considered an ideal alternative to fossil fuels for the production of sustainable liquid fuels and fine chemicals. Although biomass can be directly converted through pyrolysis, gasification, or liquefaction, the robust structure formed by the tight cross-linking of its three components and the protective effect of lignin significantly limit the efficiency of direct conversion, and the resulting products are complex and difficult to utilize directly at high value. Further promoting the high-value utilization of biomass is urgently needed. Agricultural and forestry waste biomass mainly consists of cellulose, hemicellulose, and lignin, accounting for over 90% of its dry weight, with hemicellulose accounting for approximately 15-30%. Hemicellulose is a heteropolysaccharide composed of pentose sugars (D-xylose, L-arabinose), hexose sugars (D-glucose, D-mannose, D-galactose), and uronic acid, which can be used to produce furfural, xylitol, and functional oligosaccharides. Its functional oligosaccharides have the function of improving intestinal microecological balance and are excellent functional food bases and feed additives. To prepare hemicellulose-based polymers from hemicellulose, it is necessary to preserve the original macromolecular structure of hemicellulose as much as possible during the separation process. For the production of functional oligosaccharides for pharmaceuticals or food, it is essential to ensure appropriate hydrolysis of hemicellulose to generate more hemicellulose oligosaccharides during separation. For the production of monosaccharides, furfural, and other small-molecule platform compounds from hemicellulose, deep hydrolysis during separation is more advantageous. Therefore, achieving continuous and controllable stepwise separation and enrichment of biomass hemicellulose is a crucial foundation for the diversified and high-value refining of hemicellulose.

[0003] Biomass hemicellulose extraction typically uses a batch reactor. Because the extracted product cannot be promptly discharged and collected from the reaction system, the initial extracted product undergoes severe secondary reactions, including degradation and repolymerization. Furthermore, with the accumulation of extraction and secondary degradation products, the reaction system undergoes continuous changes, severely limiting the acquisition of high-yield macromolecular hemicellulose products. Moreover, obtaining accurate information about the initial hemicellulose extracted product is difficult, if not impossible, thus significantly restricting the exploration and research of the hemicellulose extraction process and mechanism.

[0004] Researchers have conducted extensive trials and studies on the efficient separation of biomass components in recent years. Patent (CN106632735A) reports a method for extracting hemicellulose from biomass using alkaline heating and ultrasonic extraction. The filtrate is then concentrated via ultrafiltration, pH adjusted, ethanol added for precipitation, allowed to stand, centrifuged, precipitated, washed, and dried to obtain a hemicellulose sample. Patent (CN115897274A) reports a method for separating lignocellulosic biomass components and simultaneously preparing high-purity cellulose, proposing a method for extracting hemicellulose and lignin solutions from biomass using ethylene glycol phenyl ether. Patent (CN113527542A) reports a freeze-thaw assisted method for separating bagasse hemicellulose using p-toluenesulfonic acid, yielding high molecular weight hemicellulose with a purity of 90.61%–95.87%. Invention (CN102226317A), in reporting a method for the co-production of bamboo biomass fuel and bamboo pulp, involves a method for obtaining a hemicellulose extract using hot water extraction. Patent (CN115976866A) discloses a method for separating lignocellulosic biomass components through organic solvent pretreatment, involving a method of treating biomass with a triethylene glycol solution containing an acidic catalyst to obtain a filtrate containing hemicellulose and lignin. Patent (CN102041702A) discloses a method for the co-production of bleached pulp, lignin-based carbon fibers, and fuel ethanol, involving the hydrolysis of hemicellulose using hot water at 150-170℃ to obtain a hemicellulose and lignin hydrolysate. Patent (CN113186746A) discloses a lignocellulosic biomass component separation system and method, utilizing multiple series-connected reactors to perform a hydrothermal liquefaction reaction on biomass, and obtaining a hemicellulose hydrolysate through multiple solid-liquid separation devices. Patent (CN110004756A) discloses a method for extracting hemicellulose and lignin using a mixed organic solvent composed of acetone and ethylene glycol, with concentrated sulfuric acid as a catalyst, under microwave-assisted conditions to obtain a mixed solution of hemicellulose and lignin. Patent (CN109134708A) reports a method for degrading and exfoliating raw material hemicellulose and dissolving lignin using tetrahydrofurfuryl alcohol solution under hydrothermal conditions.

[0005] Although these methods all yield hemicellulose products by extracting biomass, they all utilize a batch reactor for one-pot extraction of hemicellulose, failing to achieve stepwise extraction of hemicellulose and hindering process and mechanism analysis. The products extracted at different stages are mixed together, and all inevitably undergo varying degrees of secondary degradation reactions. Summary of the Invention

[0006] To address the above problems, this invention provides a reaction apparatus and method for the stepwise continuous separation of biomass hemicellulose, effectively preventing backmixing of hemicellulose products at different extraction stages, achieving separate collection of hemicellulose products at different extraction stages, avoiding secondary degradation reactions of extracted hemicellulose products, improving the yield of macromolecular hemicellulose products, and can be extended to the research and analysis of hemicellulose extraction processes and mechanisms. The specific technical solution is as follows:

[0007] The reaction apparatus includes an extractant supply system, an extraction reaction system, and a product collection system. The extractant supply system mainly comprises an extractant storage bottle, a liquid distributor, and a horizontal flow pump. The extraction reaction system includes a rapid heating chamber, a thermal radiation extractant preheater, a flow-through reactor, temperature and pressure detection devices, and an extractant distribution filter. The product collection system includes a metal mesh filter, a cooling tank, a back pressure regulator, and a sample collection bottle. This reaction apparatus can achieve continuous, stepwise extraction and collection of biomass hemicellulose under different solvent gradients, time gradients, and temperature gradients. It significantly reduces secondary degradation reactions of extracted hemicellulose in the reaction system, preserves the macromolecular structure of hemicellulose, improves the yield of macromolecular hemicellulose polymers, and can be used to study the hemicellulose extraction process and mechanism.

[0008] The extractant supply system mainly consists of an extractant storage bottle, a liquid mixer, a horizontal pump, and a shut-off valve. The horizontal pump is located upstream of the extraction reaction system and downstream of the liquid mixer, further providing system pressure. The inlet of the liquid mixer is connected to the extractant storage bottle, and the outlet is connected to the horizontal pump. The shut-off valve controls whether the extractant is supplied to the extraction reaction system.

[0009] The extraction reaction system mainly consists of a rapid heating box, a thermal radiation extractant preheater, and a flow-through reactor. The flow-through reactor includes a flow-through reaction tube, a detachable sealing head, temperature and pressure detection devices, and an extractant distribution filter.

[0010] The rapid heating chamber provides a heating rate ≥100℃ / min for the flow-through reactor and the extractant preheater. The thermal radiation extractant preheater is located upstream of the flow-through reactor and downstream of the shut-off valve. The flow-through reactor is a tubular reactor with detachable sealing heads and temperature and pressure detection devices at both ends, and extractant distribution filters inside both ends.

[0011] The detachable sealing head is a detachable sealing device for the flow-through reactor, and is embedded through the temperature and pressure detection device. The temperature and pressure detection device is embedded inside the detachable sealing head. The extractant distribution filter is installed at the inlet and outlet ends of the flow-through reactor; the inlet end is suitable for distributing the extractant, and the outlet end is suitable for filtering solid particles.

[0012] The product collection system, used for filtering, cooling, and collecting extracted products, as well as stabilizing the reaction pressure within the flow-through reactor, mainly consists of a metal mesh filter, a cooling tank, a shut-off valve, a back pressure regulator, and a sample collection bottle. The metal mesh filter is located downstream of the flow-through reactor and upstream of the cooling tank. The cooling tank is located downstream of the metal mesh filter and connected to the shut-off valve. The back pressure regulator, adapted to regulate the reaction pressure within the flow-through reactor, is located downstream of the cooling tank and upstream of the sample collection bottle, further providing a pressure control system for the reaction system in conjunction with the horizontal flow pump. The sample collection bottle is located at the very downstream end of the device, allowing for flexible placement and removal.

[0013] Preferably, the thermal radiation extractant preheater is a coil-type preheater, and the coil is a corrosion-resistant pipe with a diameter of φ4 or smaller, and the length of the coil is sufficient to allow the extractant to pass through for 2 minutes or longer.

[0014] Preferably, the detachable sealing head is a compression fitting type fixed seal, with a necking to φ4 or less for connection with the pipeline. A sleeve is disposed 1cm or less next to the inlet and outlet of the sealing head, and the sleeve extends into the interior of the sealing head by 1cm or less to place a temperature and pressure detection device.

[0015] Preferably, the extractant distribution filter is a 5-layer sintered metal mesh sheet, wherein the metal mesh aperture is <5μm or smaller, and the water pressure drop is <0.05MPa or smaller.

[0016] Preferably, the reactor assembly consisting of a flow-through reactor and a removable sealing head is detachable at both ends and can withstand a pressure of at least 10 MPa or higher.

[0017] Preferably, the pore size of the metal mesh filter element is <2μm or smaller.

[0018] Preferably, the back pressure regulator is continuously adjustable.

[0019] Preferably, the pressure of the extractant supplied by the horizontal flow pump is equivalent to the pressure inside the flow-through reactor.

[0020] Preferably, the average temperature at the inlet and outlet of the flow-through reactor is equivalent to the reaction temperature inside the reactor.

[0021] A method for continuous stepwise extraction of hemicellulose from biomass using the aforementioned reaction apparatus, the method comprising the following steps:

[0022] Step 1: Fix the biomass pellets in the flow-through reaction tube of the device system; the bed thickness is adjustable.

[0023] Step 2: The extractant supply system supplies extractant to the extraction reaction system until the device system is full of extractant;

[0024] Step 3: Heat the extraction reaction system to the required extraction temperature, which is generally 150-200℃ depending on the specific experimental requirements.

[0025] Step 4: Turn on the horizontal flow pump to continuously and stably supply the extractant to the extraction reaction system. The flow rate is set according to the residence time of the extract in the reactor, depending on the specific experimental requirements.

[0026] Step 5: While turning on the horizontal flow pump, adjust the back pressure regulator to stabilize the temperature, flow rate and pressure inside the flow reactor. Depending on the specific experimental requirements, the pressure is generally 5-10 MPa.

[0027] Step Six: The extractant and biomass particles undergo liquid-solid separation in a flow-through reactor via the filter element.

[0028] Step 7: After the product extracted by the extractant is cooled, it is depressurized to atmospheric pressure through a back pressure regulator and collected into a sample collection bottle as needed;

[0029] The temperature of the extraction reaction system can be increased or continuously adjusted via the rapid heating chamber program.

[0030] The pressure of the extraction reaction system can be continuously adjusted by the aforementioned advection pump and back pressure regulator.

[0031] The residence time of the extracted product in the reaction system can be continuously adjusted by the advection pump and the bed thickness in the flow-through reaction tube.

[0032] By using the rapid heating chamber to raise the temperature, the continuous acquisition of products extracted in stages under different temperature conditions can be achieved.

[0033] By replacing the collection bottles in a timely manner, the products extracted at different time stages can be collected continuously and separately.

[0034] By adjusting the horizontal flow pump and the back pressure regulator, the extraction products can be continuously obtained under different pressure conditions.

[0035] By adjusting the horizontal flow pump and the bed thickness, continuous extraction of the product can be achieved under different residence time conditions.

[0036] The extracted product is discharged from the extraction reaction system in a timely and continuous manner along with the extractant, avoiding backmixing of the extracted products at different stages. The timely discharge of the product from the reaction system avoids secondary degradation reactions caused by prolonged residence of the extracted product in the reaction system.

[0037] This reaction apparatus and method can be extended to the continuous run-through of any other liquid-solid extraction reaction.

[0038] This reaction apparatus and method can also be extended to liquid-solid reactions using other organic or inorganic solvents.

[0039] The advantages of this invention compared to existing technologies are:

[0040] —It effectively avoids backmixing of the extracted products, and the hemicellulose products can be discharged from the reaction system in a timely manner, inhibiting the occurrence of secondary degradation reactions and preserving their original macromolecular structure.

[0041] —It can continuously extract hemicellulose from biomass in stages, and collect hemicellulose products extracted at different stages separately.

[0042] —It allows for flexible adjustment of extraction conditions and maintains long-term stability of the extraction reaction under certain conditions.

[0043] —The metal mesh filter prevents the constant flow pump and back pressure valve from becoming clogged;

[0044] —The residence time of the extracted product in the reaction system can be flexibly adjusted;

[0045] —This reaction apparatus can be extended to liquid-solid reactions using other organic or inorganic solvents. Attached image description:

[0046] Appendix Figure 1 This is a schematic diagram of the device of the present invention.

[0047] The attached drawings are defined as follows:

[0048] 1-Storage Bottle 1, 2-Extractant Storage Bottle 2, 3-Liquid Mixer, 4-Horizontal Flow Pump, 5-Stop Valve 1, 6-Rapid Heating Box, 7-Extractant Preheater, 8-Flow Flow Reactor, 9-Removable Sealing Head, 10-Extractant Distribution Filter Components, 11-Temperature and Pressure Detection Device, 12-Metal Mesh Filter, 13-Cooling Tank, 14-Stop Valve 2, 15-Back Pressure Regulator, 16-Sample Collection Bottle Detailed Implementation

[0049] The following specific embodiments further explain or illustrate the content of the present invention, but the embodiments should not be construed as limiting the scope of protection of the present invention. Any improvements or substitutions based on the basic spirit of the embodiments still fall within the scope of protection claimed by the claims of the present invention.

[0050] The core of this invention is to utilize a flow-through reactor to complete the liquid-solid extraction reaction of hemicellulose from biomass. By continuously controlling the extraction reaction conditions and separately collecting the extraction products, continuous stepwise extraction of hemicellulose from biomass is achieved. Figure 1 As shown, the reaction apparatus includes an extractant supply system, an extraction reaction system, and a product collection system;

[0051] The extractant supply system mainly includes extractant storage bottle 1, extractant storage bottle 2, liquid distributor 3 and horizontal flow pump 4. Extractant storage bottle 1 and extractant storage bottle 2 are connected in parallel and then connected to the liquid distributor. The liquid distributor is then connected in series with the horizontal flow pump.

[0052] The extraction reaction system mainly includes a rapid heating box 6, a thermal radiation extractant preheater 7, a flow-through reactor 8, a detachable sealing head 9, a temperature and pressure detection device 11, and an extractant distribution filter 10. The thermal radiation extractant preheater 7 and the flow-through reactor 8 are connected in series and placed inside the rapid heating box 6. The detachable sealing head 9 and the temperature and pressure detection device 11 are placed at both ends of the flow-through reactor 8. The extractant distribution filter 10 is placed inside the flow-through reactor 8.

[0053] The product collection system mainly includes a metal mesh filter 12, a cooling tank 13, a shut-off valve 14, a back pressure regulator 15, and a sample collection bottle 16, which are connected in series.

[0054] The described reaction apparatus enables the stepwise continuous extraction and collection of biomass hemicellulose under different solvent gradients, time gradients, and temperature gradients. It significantly reduces secondary degradation reactions of extracted hemicellulose in the reaction system, preserves the macromolecular structure of hemicellulose, improves the yield of macromolecular hemicellulose polymers, and can be used to study the hemicellulose extraction process and mechanism. The hemicellulose product is promptly discharged from the reaction system, avoiding backmixing of the extracted product, inhibiting secondary degradation reactions, and preserving its original macromolecular structure to obtain hemicellulose products at different extraction stages.

[0055] The following is an embodiment of the stepwise continuous extraction of biomass hemicellulose using the aforementioned reaction apparatus:

[0056] Step 1: Fix the biomass pellets in the flow-through reaction tube 8 of the device system. Extractant distribution filters 10 are installed above and below the biomass bed. The reaction tube is sealed by a detachable sealing head 9. The biomass pellets are generally ≤2mm. The bed thickness is related to the reaction tube size, extractant flow rate, and required residence time.

[0057] Step 2: Turn on the horizontal flow pump 4, and the extractant supply system supplies extractant to the extraction reaction system until the device system is full of extractant and the air in the reaction system is completely expelled.

[0058] Step 3: Close shut-off valves 5 and 14, and turn on the rapid heating chamber 6 to heat the extraction reaction system to the required extraction temperature. Depending on the specific experimental requirements, the temperature is generally 150-200℃. Determine whether the required reaction temperature has been reached based on the temperature and pressure detection device 11, i.e., the internal temperature of the reactor.

[0059] The rapid heating chamber 6 has a continuously adjustable temperature and can be set to a programmed heating mode or a constant temperature mode to obtain hemicellulose products at different temperatures or at different time periods under a certain temperature.

[0060] Step 4: After reaching the required reaction temperature, turn on the horizontal flow pump 4 and continuously and stably supply the extraction agent to the extraction reaction system as needed. The fresh extraction agent continuously carries out the extracted hemicellulose product.

[0061] According to specific experimental requirements, the flow rate is set based on the required residence time of the extract in the flow-through reaction tube 8. The residence time of the hemicellulose extract in the system is 1 second to 10 minutes. The extractant flow rate can be continuously adjusted to achieve continuous adjustment of the residence time, thereby obtaining hemicellulose products at different residence times.

[0062] Step 5: While turning on the horizontal flow pump 4, adjust the back pressure regulator 15 to finally bring the temperature, flow rate and pressure in the flow reactor to a stable state. Depending on the specific experimental requirements, the pressure is generally 3-10 MPa.

[0063] The back pressure regulator 15 can continuously adjust the reaction pressure inside the reaction tube to obtain hemicellulose products under different reaction pressures.

[0064] Step Six: The hemicellulose extraction product, carried by the unidirectionally flowing extractant, is filtered through the extractant distribution filter 10 and the metal mesh filter 12 before being promptly discharged from the reaction system. During this process, the hemicellulose solution and biomass particles undergo liquid-solid separation within the flow-through reactor via the aforementioned filter elements.

[0065] Step 7: After the hemicellulose solution is discharged from the reaction system, it is cooled by the cooling tank 13, and then the pressure is reduced to atmospheric pressure by the back pressure regulator 15 before being collected in the sample collection bottle 16.

[0066] Example 1

[0067] like Figure 1 As shown, the reaction apparatus includes an extractant supply system, an extraction reaction system, and a product collection system. The extractant supply system mainly includes an extractant storage bottle, a liquid distributor, and a horizontal flow pump. The extraction reaction system mainly includes a rapid heating chamber, a thermal radiation extractant preheater, a flow-through reactor, a removable sealing head, temperature and pressure detection devices, and an extractant distribution filter. The product collection system mainly includes a metal mesh filter, a cooling tank, a back pressure regulator, and a sample collection bottle. The apparatus is used for the stepwise extraction of biomass hemicellulose under isothermal mode, specifically including the following operations:

[0068] —Raw material pretreatment: The wood fiber plant raw materials are crushed and screened, washed with water to remove dust and impurities, and air-dried; the raw materials are agricultural and forestry wastes such as wheat straw, corn stalks, bagasse, rice straw or sawdust;

[0069] —Raw material loading: The pretreated raw materials are loaded into the flow-through reactor as described above, and properly compacted to make the porosity of the biomass bed 60-80%;

[0070] —Extractant pre-charge: Turn on the horizontal flow pump and slowly inject the extractant into the reaction system until the reaction system is full of extractant, the gas in the reaction system is completely discharged, and the biomass pellets are completely immersed in the extractant;

[0071] —Reactor heating: Turn on the rapid heating box to heat the flow-through reactor and preheater until the required extraction temperature is reached. The preferred extraction temperature is generally around 180°C.

[0072] —Continuous delivery of extractant: After the reactor and preheater reach the temperature, the horizontal flow pump is turned on to continuously and stably deliver the extractant to the reaction system. Fresh extractant is preheated to the extraction temperature by the preheater and then continuously and stably injected into the flow-through reactor. When the extractant flows through the biomass bed in the reactor, it continuously extracts hemicellulose. The hemicellulose extract is continuously carried out of the reactor by the extractant.

[0073] The extraction agent delivery rate is set according to the residence time of the extracted product in the reactor. In order to avoid severe secondary degradation of the hemicellulose extract, the residence time of the extracted product in the reactor should be less than 5 minutes.

[0074] With the continuous delivery of fresh extractant, the bonds between hemicellulose and other components are gradually hydrolyzed and broken, and hemicellulose is gradually extracted and carried out, realizing stepwise extraction of hemicellulose under constant temperature mode.

[0075] —Stepwise collection of extraction products: During the continuous extraction of hemicellulose with the extractant, hemicellulose products are collected at intervals of 5-20 minutes at different time points.

[0076] —The results of hemicellulose stepwise extraction under isothermal mode are as follows:

[0077]

[0078] Note: Hemicellulose extraction rate is the ratio of hemicellulose dissolution to the initial total amount of hemicellulose in the raw material; hemicellulose cumulative extraction rate is the ratio of the total amount of hemicellulose dissolution during the extraction time to the initial total amount of hemicellulose in the raw material; hemicellulose oligosaccharide content is the ratio of the amount of dissolved hemicellulose oligosaccharides to the total amount of dissolved hemicellulose (monosaccharides and oligosaccharides); the extraction effect of a batch reactor refers to the overall effect under the same conditions as a flow-through reactor, such as temperature, time, and liquid-to-solid ratio.

[0079] Table 1 shows that the hemicellulose extraction rate, hemicellulose oligosaccharide content, and hemicellulose molecular weight differ at different extraction time periods, indicating that the apparatus and method of this invention can achieve stepwise extraction of hemicellulose under isothermal mode to obtain hemicellulose oligosaccharide products with different properties. Compared with the extraction effect of a batch reactor under the same conditions, the hemicellulose extraction rate is significantly improved (90.1% vs. 84.3%); the hemicellulose oligosaccharide content in the product is significantly improved (>60% vs. 46.6%), and the molecular weight of the obtained hemicellulose is significantly improved, indicating that the apparatus and method of this invention significantly inhibits the secondary degradation reaction of the hemicellulose extraction product.

[0080] Example 2:

[0081] like Figure 1 As shown, the reaction apparatus includes an extractant supply system, an extraction reaction system, and a product collection system. The extractant supply system mainly includes an extractant storage bottle, a liquid distributor, and a horizontal flow pump. The extraction reaction system mainly includes a rapid heating chamber, a thermal radiation extractant preheater, a flow-through reactor, a removable sealing head, temperature and pressure detection devices, and an extractant distribution filter. The product collection system mainly includes a metal mesh filter, a cooling tank, a back pressure regulator, and a sample collection bottle. The apparatus is used for stepwise extraction of biomass hemicellulose under a programmed temperature ramp mode, specifically including the following operations:

[0082] —Raw material pretreatment: The wood fiber plant raw materials are crushed and screened, washed with water to remove dust and impurities, and air-dried; the raw materials are agricultural and forestry wastes such as wheat straw, corn stalks, bagasse, rice straw or sawdust;

[0083] —Raw material loading: The pretreated raw materials are loaded into the flow-through reactor as described above, and properly compacted to make the porosity of the biomass bed 60-80%;

[0084] —Extractant pre-charge: Turn on the horizontal flow pump and slowly inject the extractant into the reaction system until the reaction system is full of extractant, the gas in the reaction system is completely discharged, and the biomass pellets are completely immersed in the extractant;

[0085] —Reactor heating: Turn on the rapid heating box to program the temperature of the flow reactor and preheater. The temperature range of 120-200℃ is increased in steps at 20℃ intervals. The preferred extraction temperature is maintained for 30-60 minutes.

[0086] —Continuous delivery of extractant: After the reactor and preheater reach the initial extraction temperature, the horizontal flow pump is turned on to continuously and stably deliver the extractant to the reaction system. The fresh extractant is preheated to the extraction temperature by the preheater and then continuously and stably injected into the flow-through reactor. When the extractant flows through the biomass bed in the reactor, it continuously extracts hemicellulose. The hemicellulose extract is continuously carried out of the reactor by the extractant.

[0087] The extraction agent delivery rate is set according to the residence time of the extracted product in the reactor. In order to avoid severe secondary degradation of the hemicellulose extract, the residence time of the extracted product in the reactor should be less than 5 minutes.

[0088] As fresh extractant is continuously delivered, the extraction temperature gradually increases, the bonds between hemicellulose and other components are gradually hydrolyzed and broken, and hemicellulose is gradually extracted and carried out, realizing stepwise extraction of hemicellulose under programmed temperature rise mode.

[0089] —Stepwise collection of extraction products: During the continuous extraction of hemicellulose by the extractant, hemicellulose products at different temperature ranges are collected separately.

[0090] The results of hemicellulose stepwise extraction products obtained at different temperature ranges are as follows:

[0091]

[0092]

[0093] Note: Hemicellulose extraction rate is the ratio of the amount of hemicellulose dissolved to the initial total amount of hemicellulose in the raw material; hemicellulose cumulative extraction rate is the ratio of the total amount of hemicellulose dissolved during the extraction time to the initial total amount of hemicellulose in the raw material; hemicellulose oligosaccharide content is the ratio of the amount of dissolved hemicellulose oligosaccharides to the total amount of dissolved hemicellulose (monosaccharides and oligosaccharides).

[0094] As can be seen from Table 2, the extraction rate and content of hemicellulose oligosaccharides differ at different extraction temperatures. Hemicellulose is mainly extracted at 150-180℃, and it mainly exists (>80%) in the form of hemicellulose oligosaccharides. The molecular weight of hemicellulose extracted at different temperatures also differs, indicating that the device and method of the present invention can achieve stepwise extraction of hemicellulose under variable temperature mode to obtain hemicellulose oligosaccharide products with different properties.

[0095] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the equivalent meaning and scope of the claims be included within the protection scope of the present invention.

Claims

1. A reaction apparatus for continuous stepwise extraction of hemicellulose from biomass, characterized in that... The apparatus for the stepwise and continuous extraction and collection of biomass hemicellulose under different solvent gradients, time gradients, and temperature gradients, and for significantly reducing the secondary degradation reaction of extracted hemicellulose in the reaction system, comprises: An extraction reaction system, said extraction reaction system being suitable for liquid-solid extraction reactions; An extraction agent supply system, said extraction agent supply system being adapted to supply pressurized extraction agent to the extraction reaction system. The extraction agent supply system mainly consists of an extraction agent storage bottle one (1), an extraction agent storage bottle two (2), a liquid mixer (3), a horizontal flow pump (4), and a shut-off valve one (5). —A horizontal flow pump (4) is adapted to control the supply flow rate of the extractant. The horizontal flow pump (4) is located upstream of the extraction reaction system and downstream of the liquid mixer, and further provides system pressure. —Liquid mixer (3), suitable for controlling the mixing ratio of different extractants, the inlet end of the liquid mixer is connected to extractant storage bottle one (1) and extractant storage bottle two (2), and the outlet section is connected to the horizontal flow pump (4). —Stop valve 1 (5) is adapted to control the supply of extractant to the extraction reaction system; —Rapid heating box (6), suitable for heating flow reactor (8) and extractant preheater (7), blower heating, heating rate ≥100℃ / min; —Thermal radiation extractant preheater (7), adapted to preheat extractant to extraction temperature, is located upstream of the flow-through reactor (8) and downstream of the shut-off valve (5); —Flow-through reactor (8) is a tubular reactor suitable for placing a solid bed with controllable bed thickness. The front and rear ends of the flow-through reactor are equipped with detachable sealing heads (9) and temperature and pressure detection devices (11). The front and rear ends are equipped with extractant distribution filter devices (10). —The removable sealing head (9), the removable sealing device of the flow reactor (8), is embedded through the temperature and pressure detection device (11); —Temperature and pressure detection device (11), suitable for detecting the temperature and pressure at both ends of the flow reactor (8), is embedded inside the removable sealing head (9); —Extractant distribution filter element (10) is installed at the inlet and outlet ends of the flow-through reactor (8), the inlet end is suitable for distributing extractant, and the outlet end is suitable for filtering solid particles; A product collection system, adapted for filtering, cooling and collecting extracted products, and for stabilizing the reaction pressure within the flow-through reactor (8), The product collection system mainly consists of a metal mesh filter (12), a cooling tank (13), a second shut-off valve (14), a back pressure regulator (15), and a sample collection bottle (16). —A metal mesh filter (12), suitable for filtering solid particles carried in the extraction product, is placed downstream of the flow-through reactor (8) and upstream of the cooling tank; —Cooling tank (13), which is suitable for cooling the extracted product, is located downstream of the metal mesh filter (12) and connected to shut-off valve two (14). —Back pressure regulator (15), which is adapted to regulate the reaction pressure in the flow reactor (8), is located downstream of the cooling tank (13) and upstream of the sample collection bottle (16), and works in conjunction with the horizontal flow pump (4) to further provide a reaction system pressure control system; —Sample collection bottle (16) is suitable for collecting and storing extract samples and can be flexibly placed and removed.

2. The apparatus according to claim 1, characterized in that... The thermal radiation extractant preheater (7) is a coil preheater, the coil is a corrosion-resistant pipe with a diameter of ≤φ4, and the length of the coil is such that the extractant passage time is ≥2 minutes; —The detachable sealing head (9) is a compression fitting type fixed seal, which is necked to ≤φ4 and connected to the pipeline. A sleeve is installed ≤1cm away from the inlet and outlet of the sealing head. The sleeve extends into the interior of the sealing head for a certain distance, which is ≤1cm, to place the temperature and pressure detection device. —The extractant distribution filter element (10) is a 5-layer sintered metal mesh sheet, wherein the pore size of the distribution filter element is ≤ 5μm and the water pressure drop is ≤ 0.05MPa; —A reactor assembly consisting of a flow-through reactor (8) and a detachable sealing head (9) with detachable ends and pressure resistance ≥10 MPa; —Distributed filter device (10) filter element pore size ≤ 2μm; —The back pressure regulator is continuously adjustable; —The pressure of the extractant supplied by the horizontal flow pump is equivalent to the pressure inside the flow-through reactor; —The average temperature at the inlet and outlet of a flow-through reactor is equivalent to the reaction temperature inside the reactor.

3. A method for continuous stepwise extraction of biomass hemicellulose using the apparatus of claim 1, the method comprising the following steps: —Biomass pellets are fixed in a flow-through reactor, and the bed thickness is adjustable; —The extractant supply system supplies extractant to the extraction reaction system until the apparatus of claim 1 is full of extractant; —Heat the extraction reaction system to the required extraction temperature, which is 150-200℃ depending on the specific experimental requirements; —Turn on the horizontal flow pump to continuously and stably supply the extractant to the extraction reaction system as needed. The flow rate is set according to the required residence time of the extract in the reactor, depending on the specific experimental requirements. —While turning on the horizontal flow pump, adjust the back pressure regulator to stabilize the temperature, flow rate and pressure inside the flow reactor. The pressure should be 5-10 MPa depending on the specific experimental requirements. —The extractant and biomass pellets are separated into liquid and solid by a metal mesh filter in a flow-through reactor. —After the extractant is cooled, the product is depressurized to atmospheric pressure by a back pressure regulator and collected into a sample collection bottle as needed.

4. The method according to claim 3, characterized in that... The temperature of the extraction reaction system can be continuously adjusted using a rapid heating box (6); —The pressure of the extraction reaction system can be continuously adjusted by a flow pump and a back pressure regulator; —The residence time of the extracted product in the reaction system can be continuously adjusted by the bed thickness in the horizontal flow pump and the flow-through reaction tube as described in claim 1; —By using a rapid heating chamber to program the temperature rise, continuous acquisition of products extracted in stages under different temperature conditions can be achieved; —By timely replacing the collection bottle as described in claim 1, continuous acquisition of products extracted in stages at different time periods can be achieved; —By adjusting the advection pump and back pressure regulator, the extraction products can be continuously obtained under different pressure conditions; —By adjusting the horizontal flow pump and the bed thickness, continuous extraction of the product can be achieved under different residence time conditions; —The extracted product is discharged from the extraction reaction system in a timely and continuous manner along with the extractant, avoiding backmixing of the extracted products at different stages. The timely discharge of the product from the reaction system avoids secondary degradation reactions caused by prolonged residence of the extracted product in the reaction system.

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