Novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method

Abstract

The invention relates to the technical field of organic synthesis, in particular to a novel purification and hydrolysis method for octadecanedioic acid synthesized by a fermentation method, which comprises the following steps of: performing esterification reaction on an octadecanedioic acid crude product which is used as an initial raw material in a rectifying tower kettle to generate a substance as shown in a formula II, and rectifying and purifying the substance as shown in the formula II to obtain the octadecanedioic acid. And hydrolyzing the high-purity substance as shown in the formula II through an acid-catalyzed microchannel to obtain the high-purity substance as shown in the formula I. An acid catalysis hydrolysis route is adopted, the intermediate monomethyl ester can be promoted to be completely converted into target diacid, it is ensured that the purity of the final product is stable and larger than or equal to 99.0%, the residual monomethyl ester is lower than the detection limit by 0.1%, and the high purity of the final product is ensured; continuous operation is realized in the whole process from esterification, purification to hydrolysis, and the production efficiency is high; the reaction rectification technology realizes efficient utilization of materials and energy, methanol is recovered and recycled on line, raw material consumption and discharge of three wastes are reduced, and the requirements of green chemical industry are met.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a novel purification and hydrolysis method for synthesizing octadecanoic acid by fermentation. Background Technology

[0002] Octadecanedioic acid is a long-chain dicarboxylic acid, appearing as a white crystalline powder. It exhibits typical esterification and amidation reactivity of dicarboxylic acids and can be prepared through vegetable oil pyrolysis, chemical synthesis, or bio-fermentation. In the field of pharmaceutical raw materials, its core application is as a drug synthesis intermediate. It functions by constructing long-chain hydrophobic frameworks or functional group connecting bridges. For example, it is used in the preparation of liposome drug carriers, structural modification of nonsteroidal anti-inflammatory drugs, and the synthesis of some lipid-lowering and antibacterial drugs. As a hydrophobic fragment, it regulates drug bioavailability and tissue distribution characteristics. It can also be used to improve the compatibility between drug excipients and active pharmaceutical ingredients.

[0003] However, the industrial production and purification of octadecanoic acid has always faced severe challenges. Traditional chemical synthesis routes are lengthy, costly, and environmentally polluting. In recent years, the technology of synthesizing octadecanoic acid based on microbial fermentation has attracted widespread attention due to its mild conditions and renewable raw materials. However, the fermentation products obtained by this route have complex compositions and are difficult to separate and purify, resulting in generally low purity of the final product, which is difficult to meet the stringent requirements for monomer purity (usually ≥99.0%) for the synthesis of high-end polymers.

[0004] To purify crude octadecanoic acid obtained from fermentation, the industrial process often employs a pre-esterification followed by hydrolysis. This involves first esterifying the crude acid with methanol to form dimethyl octadecanoate, then purifying it using its easy distillation properties, and finally hydrolyzing the high-purity ester back to the acid. However, in the final hydrolysis step, traditional processes commonly use alkali-catalyzed hydrolysis. This process has a fatal flaw: due to the steric hindrance effect of the long carbon chain, the alkali-catalyzed hydrolysis reaction is often incomplete, easily generating and leaving behind monomethyl octadecanoate as an intermediate. This monomethyl ester impurity has extremely similar physicochemical properties to the target product, octadecanoic acid, and is very difficult to completely remove using conventional separation methods such as crystallization and extraction. This results in the final product purity consistently failing to exceed the 99.0% bottleneck, severely restricting its application in high-value-added fields. Summary of the Invention

[0005] The purpose of this invention is to provide a novel purification and hydrolysis method for the synthesis of octadecanoic acid by fermentation, in order to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution.

[0007] A novel purification and hydrolysis method for synthesizing octadecanoic acid by fermentation involves using crude octadecanoic acid synthesized by fermentation as a starting material, undergoing an esterification reaction in a distillation column to generate the substance shown in Formula II. The substance shown in Formula II is then purified by distillation. The high-purity substance shown in Formula II is then subjected to acid-catalyzed microchannel hydrolysis to obtain the high-purity substance shown in Formula I. The method specifically includes the following steps:

[0008] Step 1: The fermentation broth is subjected to online acid precipitation, solid-liquid separation, and drying to obtain the crude product of technical grade formula I; Step 2: In a distillation system with a strong acid cation exchange resin catalytic section, the substance shown in the technical grade crude product of Formula I is continuously esterified with methanol in countercurrent contact and water is removed to obtain crude dimethyl octadecanoate. Step 3: The crude dimethyl octadecanoate is subjected to thin-film evaporation and short-path molecular distillation in sequence to obtain the substance shown in Formula II with high purity; Step 4: The substance shown in Formula II is subjected to a microchannel reaction with water, solvent and acid catalyst, and continuously hydrolyzed for 5–30 min at 120–160 °C and 0.5–3.0 MPa. The generated methanol is removed online, and the hydrolysate is cooled, acidified, separated from solid and liquid and dried to obtain the substance shown in Formula I with a purity ≥99.0%.

[0009] Preferably, the novel purification and hydrolysis method is scaled up using a multi-channel parallel system; the multi-channel parallel system includes an online acid precipitation tank, a solid-liquid separation unit, a drying unit, a reactive distillation column with a resin catalytic section, a thin-film evaporator, a short-path molecular distillation apparatus, and a microchannel reactor connected in sequence; wherein, the solid-liquid separation unit is a plate and frame filter, and the drying unit is a fluidized bed dryer.

[0010] Preferably, the esterification reaction in step two is carried out at atmospheric pressure and 50–90°C for 2–4 hours. The distillate from the esterification reaction is a methanol / water azeotrope, which is recycled by absorbing water through a molecular sieve.

[0011] Preferably, during the film evaporation in step three, the feed rate is 30-40 kg / h, the evaporation rotor speed is 225-270 rpm, the operating pressure is 1-10 mbar, the heating temperature is 200-220℃, the top fraction temperature is 180-185℃, and the final fraction temperature is >190℃. In step three, during short-path molecular distillation, the operating pressure is 0.01-0.1 mbar, the heating surface temperature is 150-170℃, the condensing surface temperature is 80-100℃, the distance between the evaporating and condensing surfaces is <2cm, the feed rate is 0.5-2 kg / h·m², the scraper speed is 80%-95% of the maximum design speed, and the material preheating temperature is 120-140℃.

[0012] Preferably, the substance shown in Formula II has a purity >95% after thin-film evaporation and a purity >99% after short-path molecular distillation.

[0013] Preferably, the acid catalyst in step four is one or more of sulfuric acid, p-toluenesulfonic acid, and phosphoric acid, and the amount used is 0.05–1.0 wt% of the mass of the substance shown in Formula II. The solvent in step four is one or a mixture of several of dioxane, acetic acid, DMF, and NMP. The concentration of the reaction solution is 20-50 wt%, the amount of water used is 0.1-1.0 wt% of the mass of the substance shown in Formula II, the reaction temperature is 110-130℃, and the retention time is 25-30 min.

[0014] Preferably, step one employs a fluidized bed dryer, which includes an insulated outer tank, an inner tank, a screw conveyor mechanism, and a heat supply system. The insulated outer tank is fixed outside the inner tank, forming a heating chamber between them. The heat supply system supplies heat to the heating chamber. The inner tank has an inlet on one side extending upwards to the outside of the insulated outer tank, and an outlet on the other side extending downwards to the outside of the insulated outer tank. The screw conveyor mechanism is used to move the material from the inlet side to the outer tank. A spiral conveyor is used on one side of the discharge port; a crushing material feeding mechanism is installed above the insulated outer tank and connected to the inlet; the crushing material feeding mechanism includes a feeding box with its bottom connected to the inlet and four crushing rollers rotatably installed in the feeding box; the four crushing rollers are arranged along a V-shaped path, and there is a discharge gap between adjacent crushing rollers; one end of each crushing roller extends through to the outside of the feeding box and is fixedly fitted with a gear, and the gears on adjacent crushing rollers mesh accordingly; one of the crushing rollers is linked with the spiral conveyor mechanism.

[0015] Preferably, the screw conveyor mechanism includes an auger conveyor rod and a drive motor; the auger conveyor rod is coaxially rotatably installed inside the inner tank, and the outer edge of the auger conveyor rod is movably fitted against the inner wall of the inner tank; both ends of the auger conveyor rod extend through to the outside of the insulated outer tank; a motor base is fixed to one side of the insulated outer tank, the drive motor is fixed to the motor base, and the output shaft of the drive motor is fixedly connected to the end of the auger conveyor rod; a first pulley is fixedly fitted to the end of one crushing roller located outside the feeding box; a second pulley is fixedly fitted to the end of the auger conveyor rod away from the drive motor; a drive belt is nested on both the first pulley and the second pulley in a common driving manner.

[0016] Preferably, the heat supply system includes a blower, a heater, and an air supply duct; the blower and heater are located on the side of the insulated outer tank, and the air outlet of the blower is connected to the air inlet of the heater through the air supply duct; the air outlet of the heater is connected to one end of the air supply duct, and the other end of the air supply duct is connected to the end of the insulated outer tank away from the drive motor and communicates with the heating cavity; multiple annular support plates are fixedly fitted at intervals along the length of the outer wall of the inner tank, and the peripheral wall of each annular support plate is fixed to the inner wall of the insulated outer tank; each annular support plate has a notch, and the notches on adjacent annular support plates are staggered vertically; multiple air inlets are opened at intervals along the length of the bottom of the inner tank.

[0017] Preferably, the portion of the discharge port located within the heating clamp has several inlet channels arranged in a ring array around the discharge port axis to connect the discharge port and the heating clamp.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0019] This invention employs an acid-catalyzed hydrolysis route, which enables the complete conversion of the intermediate monomethyl ester into the target diacid, ensuring a stable final product purity of ≥99.0% and a monomethyl ester residue below the detection limit of 0.1%, thus guaranteeing the high purity of the final product. From esterification and purification to hydrolysis, the entire process achieves continuous operation and high production efficiency. The reactive distillation technology enables efficient utilization of materials and energy, with online recovery and recycling of methanol, reducing raw material consumption and waste emissions, and meeting the requirements of green chemical engineering.

[0020] This invention uses a fluidized bed dryer to dry materials. The fluidized bed dryer uses four crushing rollers arranged along a V-shaped path and rotating in opposite directions to continuously shear and tear the wet filter cake. This gently disperses the material, preventing lumpy material from directly entering the drying process and causing incomplete drying, thus meeting the required dryness level. It also reduces the amount of fine powder generated by excessive crushing, avoiding dust and wall sticking caused by excessive powder during the drying process.

[0021] This invention combines external heating of the heating chamber with internal heat flow ejected upward through the air inlet to form a three-dimensional heating ring that integrates internal and external heating. It not only conducts heat through the inner tank wall but also uses the rising internal hot air flow to fluidize the material, thereby enhancing the gas-solid contact efficiency.

[0022] The four crushing rollers in this invention have a hollow structure and serve as pipelines for a pneumatic conveying system. When the dried hot material and airflow pass through the inside of the crushing rollers, their heat is indirectly transferred to the newly added wet material through the pipe wall, thus preheating the material. Furthermore, the crushing component serves as a heat exchange unit, eliminating the need for an additional preheating source and reducing energy consumption. Attached Figure Description

[0023] Figure 1 This is a flowchart of the steps of the novel purification and hydrolysis method. Figure 2 The liquid phase purity spectrum of octadecanoic acid (Formula I), the product of Example 1; Figure 3 This is a liquid phase purity spectrum of the octadecanoic acid alkaline hydrolysis product of the control example; Figure 4 The liquid phase purity spectrum of dimethyl octadecanoate (Formula II), the product of Example 1; Figure 5 The 1H NMR spectrum of octadecanoic acid (Formula I), the product of Example 1; Figure 6 The 1H NMR spectrum of dimethyl octadecanoate (Formula II), the product of Example 1; Figure 7 This is a schematic diagram of the overall structure of the fluidized bed dryer used in this method; Figure 8 for Figure 7 Another perspective view of the structure shown; Figure 9 for Figure 7 The diagram shows a partial structure. Figure 10 This is a partial structural diagram of the feeding box in this invention; Figure 11 for Figure 10 The diagram shows a partial structure. Figure 12 This is a schematic diagram of the structural distribution of the crushing roller in this invention; Figure 13 This is a schematic diagram illustrating the crushing principle of the crushing roller in this invention; Figure 14 This is a schematic diagram of the internal structure of the insulated outer tank in this invention; Figure 15 for Figure 14 Enlarged schematic diagram of the structure at point A in the middle; Figure 16 This is a schematic diagram of the internal structure of the inner tank in this invention; Figure 17 for Figure 16 Enlarged schematic diagram of the structure at point B.

[0024] In the diagram: 1. Insulated outer tank; 11. Annular support plate; 111. Notch; 2. Inner tank; 201. Air inlet; 202. Core; 21. Feed inlet; 22. Discharge outlet; 221. Inlet channel; 3. Screw conveyor rod; 31. Motor base; 32. Drive motor; 4. Feeding box; 5. Crushing roller; 51. Gear; 52. First pulley; 53. Second pulley; 54. Transmission belt; 6. Blower; 601. Air supply duct; 61. Heater; 62. Air supply duct; 63. First conveying duct; 7. Air inlet box; 8. Air outlet box; 81. Second conveying duct. Detailed Implementation

[0025] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0026] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "installation" should be interpreted broadly, wherein "fixed" means that the devices or elements are connected to each other and their relative positional relationship remains unchanged after connection. The directional terms mentioned in the embodiments of the present invention are only for reference to the directions in the accompanying drawings, and are intended to better and more clearly illustrate and understand the embodiments of the present invention. They are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limitations on the embodiments of the present invention. Example 1

[0027] Please see Figures 1-6 This embodiment provides a novel purification and hydrolysis method for synthesizing octadecanoic acid by fermentation. In this method: The starting material is octadecanoic acid fermentation broth obtained by microbial fermentation, which is initially filtered to remove bacterial cells; The main equipment includes an online acid precipitation tank, a plate and frame filter, a fluidized bed dryer, a reactive distillation column filled with a strong acid cation exchange resin (such as Amberlyst-15), a thin-film evaporator, a short-path molecular distillation apparatus, a microchannel reactor, and a methanol recovery system (condenser and molecular sieve water absorber). The microchannel reactor is made of silicon carbide or Hastelloy, and in this embodiment, Hastelloy is preferred. The inner diameter of the microchannel reactor is 0.5–2.0 mm, and in this embodiment, 1 mm is preferred.

[0028] The specific steps are as follows: Step 1: Preprocessing 1000 kg of octadecanoic acid fermentation broth was pumped into an online acid precipitation tank. 20% dilute sulfuric acid was slowly added under stirring to adjust the pH to 2.0-3.0, allowing octadecanoic acid to fully crystallize and precipitate. Subsequently, solid-liquid separation was performed using a plate and frame filter press to obtain a wet filter cake. The wet filter cake was then sent to a fluidized bed dryer and dried at 80°C to constant weight, yielding approximately 85 kg of technical-grade crude octadecanoic acid (purity approximately 90%).

[0029] Step 2: Continuous esterification by reactive distillation The above 85 kg crude octadecanoic acid was mixed with 255 kg methanol (as solvent and reactant, mass ratio of about 1:3) and preheated. The mixture was then fed from the middle of the reactive distillation column. The bottom of the column was packed with a strong acid cation exchange resin as a catalyst. The bottom temperature was controlled at 70°C and the top temperature at 65°C. The continuous countercurrent esterification reaction was carried out under atmospheric pressure. The distillate at the top of the column is an azeotrope of methanol and water. After condensation, it enters the molecular sieve water absorber. The methanol phase (containing about 98% methanol) is refluxed back into the column or recycled as recovered methanol. The molecular sieve is replaced, dried and recycled periodically. During the reaction, the material in the bottom of the column is monitored by HPLC. When the raw material octadecanoic acid has basically reacted completely (about 3 hours later), the feed is stopped, the temperature of the bottom of the column is maintained, and the crude liquid octadecanoic acid dimethyl ester is discharged from the bottom of the column and enters the molecular distillation device.

[0030] Step 3: Molecular distillation for precise purification The crude esterified product was pumped into a thin-film evaporator at a rate of 35 kg / h. The evaporator operating pressure was set to 5 mbar, the heating temperature to 210 °C, and the evaporator rotor speed to 250 rpm. Under these conditions, light component impurities (including residual methanol, water, and low-boiling-point ester impurities) were distilled off from the top (top temperature controlled at 182 °C), while heavy components (mainly dimethyl octadecanoate) were discharged from the bottom. After thin-film evaporation, approximately 90 kg of dimethyl octadecanoate intermediate was obtained, with a purity of 96.5% as determined by HPLC. The intermediate product was preheated to 130°C and then fed into a short-path molecular distillation apparatus at a feed rate of 1.5 kg / h·m². The operating pressure was set to 0.05 mbar, the heating surface temperature to 160°C, the condensing surface temperature to 90°C, the distance between the evaporating and condensing surfaces to 1.5 cm, and the scraper rotation speed to 90% of the maximum design speed. Under these high vacuum and precise temperature control conditions, high-purity dimethyl octadecanoate vapor condensed on the condensing surface, yielding approximately 87 kg of distillate. HPLC analysis showed that its purity reached 99.5%. Figure 4 This satisfies the requirements for subsequent hydrolysis.

[0031] Furthermore, the large specific surface area of ​​the microchannel reactor enables highly efficient mass and heat transfer, allowing the hydrolysis reaction to be completed within minutes and greatly suppressing the occurrence of side reactions. At the same time, continuous operation ensures the uniformity and stability of the product batches. The purification strategy of combining thin-film evaporation and short-path molecular distillation is particularly suitable for separating high-boiling-point, heat-sensitive long-chain diesters, effectively removing impurities such as pigments and polymers, and providing high-purity raw materials for subsequent hydrolysis reactions.

[0032] Step 4: Microchannel continuous hydrolysis High-purity dimethyl octadecanoate (Formula II) was mixed with acetic acid, deionized water, and p-toluenesulfonic acid as catalyst in a certain proportion to prepare a homogeneous solution. The composition of the reaction solution was as follows: dimethyl octadecanoate concentration 25 wt%, water amount 0.5 wt% of ester mass, and p-toluenesulfonic acid amount 0.5 wt% of ester mass. The reaction solution was pumped into a Hastelloy microchannel reactor using a high-pressure pump. The reaction temperature was controlled at 120°C, the system pressure at 2.0 MPa, and the material retention time in the reactor was 30 minutes. Methanol produced during the reaction flowed out with the material and was subsequently separated and removed online in a flash tank. The hydrolysate flowing out of the microchannel reactor was cooled to room temperature, and octadecanoic acid gradually crystallized out. A small amount of dilute sulfuric acid was then added to promote complete crystallization, followed by filtration. The solid was washed three times with deionized water. The resulting wet crystals were dried in a vacuum drying oven at 80°C for 6 hours, with a hydrolysis molar yield of 94.6%.

[0033] Quality analysis was performed on the final octadecanoic acid product: Appearance: White powder; Purity (HPLC): 99.9%; Monomethyl ester residue (HPLC): such as Figure 2 As shown, it was not detected (below the detection limit of 0.1%). Example 2

[0034] This example is a comparative example, and the method is as follows: 10g of dimethyl octadecanoate (Formula II) obtained in step three was hydrolyzed using the traditional alkaline hydrolysis method. 40g of tetrahydrofuran and 40g of water were used as a mixed solvent, and 2.4g of lithium hydroxide was used as the alkali. The mixture was refluxed for 10 hours. After the reaction, hydrochloric acid was added to adjust the pH to 1-2. The resulting solid was filtered, dissolved in 20g of DMF at elevated temperature, and then ethyl acetate was added dropwise until solid appeared. The mixture was then cooled slowly to allow crystallization until room temperature. After stirring at room temperature for 2 hours, the solid was filtered. 8g of a white solid was obtained after drying, with a molar yield of 87%. HPLC analysis showed a purity of 98.3%, with an impurity peak at 24.25 min indicating monomethyl octadecanoate. Figure 3 Compared with Example 1, the acid hydrolysis reaction was more thorough and the yield was higher. Example 3

[0035] Please see Figures 7-17 This embodiment provides a detailed explanation of the fluidized bed dryer used in Embodiment 1, as follows: The fluidized bed dryer includes an insulated outer tank 1, an inner tank 2, a spiral conveying mechanism, and a heat supply system. The insulated outer tank 1 is fixed to the outside of the inner tank 2, forming a heating chamber between the insulated outer tank 1 and the inner tank 2. The heat supply system supplies heat to the heating chamber. The inner tank 2 has an inlet 21 extending upward through to the outside of the insulated outer tank 1 on one side and an outlet 22 extending downward through to the outside of the insulated outer tank 1 on the other side. The spiral conveying mechanism is located inside the inner tank 2 and is used to spirally convey the material inside the inner tank 2 from the inlet 21 side to the outlet 22 side. A material feeding mechanism connected to the inlet 21 is provided above the insulated outer tank 1 to shake and feed the material into the inlet 21.

[0036] like Figure 14 and Figure 16 As shown, the screw conveyor mechanism includes an auger conveyor rod 3 and a drive motor 32. The auger conveyor rod 3 is coaxially and rotatably installed inside the inner tank 2, and the outer edge of the auger conveyor rod 3 is movably fitted with the inner wall of the inner tank 2, forming a spiral channel between the auger conveyor rod 3 and the inner wall of the inner tank 2. Both ends of the auger conveyor rod 3 extend through to the outside of the insulated outer tank 1. A motor base 31 is fixed on one side of the insulated outer tank 1, and the drive motor 32 is fixed on the motor base 31. The output shaft of the drive motor 32 is fixedly connected to the end of the auger conveyor rod 3. When the drive motor 32 is powered on, its output shaft drives the auger conveyor rod 3 to rotate inside the inner tank 2, which can spirally push the material that falls into the inner tank 2 from the inlet 21 to the outlet 22.

[0037] like Figure 2 As shown, the heat supply system includes a blower 6, a heater 61, and an air supply duct 62. The blower 6 and the heater 61 are located on the side of the insulated outer tank 1. The blower 6 has a built-in filter structure to filter out dust particles and impurities in the air, preventing dust particles and impurities from being mixed into the material later. The air outlet of the blower 6 is connected to the air inlet of the heater 61 through the air supply duct 601. The air outlet of the heater 61 is connected to one end of the air supply duct 62. The other end of the air supply duct 62 is connected to the end of the insulated outer tank 1 away from the drive motor 32 and is connected to the heating chamber.

[0038] In step one of Example 1, after solid-liquid separation by plate and frame filter press, a wet filter cake is obtained. The crushed material feeding mechanism is connected to the plate and frame filter press. The wet filter cake is fed into the crushed material feeding mechanism. The crushed material feeding mechanism shakes and crushes the wet filter cake into granular material to avoid the material from clumping together and facilitates subsequent fluidized drying. Granular material is fed into the inner tank 2 through the feed port 21. At the same time, the blower 6 works and supplies air to the heating chamber through the air supply pipe 601 and the air supply pipe 62. The airflow can be heated by the heater 61 to ensure that the airflow temperature entering the heating chamber is 82-85℃. The heat flow can heat the inner tank 2 in the heating chamber. When the screw conveyor works, it can push the granular material falling into the inner tank 2 toward the discharge port 22. During this process, the screw conveyor can turn the material over, further break it down, and ensure that the material is heated evenly. In addition, the screw conveyor can extend the travel distance of the material in the inner tank 2, ensuring more thorough drying. Finally, when the material is pushed to the discharge port 22, the drying is completed, and the material is discharged through the discharge port 22 and transferred to the next process.

[0039] like Figure 16 and Figure 17 As shown, the bottom of the inner tank 2 has multiple air inlets 201 spaced apart along its length. Each air inlet 201 extends vertically, and the top of the air inlet 201 is connected to the inside of the inner tank 2, while the bottom is connected to the heating chamber. During the drying process, the heat flow in the heating chamber can flow vertically upward from the bottom of the inner tank 2 into the inner tank 2 through the air inlets 201. Due to heat loss, the temperature of the heat flow entering the inner tank 2 is about 80°C.

[0040] The hot flow entering the inner tank 2 comes into direct contact with the material and can blow the material upward. Combined with the screw conveyor, the material is fluidized and floats in the inner tank 2, improving the drying effect. At the same time, it works in conjunction with the hot flow in the heating jacket to form a synergistic working mechanism of external heat supply and internal heat contact and material throwing, thereby improving drying efficiency.

[0041] like Figure 14 As shown, multiple annular support plates 11 are fixedly mounted on the outer wall of the inner tank 2 along its length. The peripheral wall of each annular support plate 11 is fixed to the inner wall of the insulated outer tank 1. The annular support plates 11 are used to fix the insulated outer tank 1 and the inner tank 2 coaxially. In addition, each annular support plate 11 is provided with a notch 111 for heat flow, and the notches 111 on adjacent annular support plates 11 are staggered vertically. After the heat flow enters the inner tank 2, it flows back and forth in the heating cavity through the staggered notches 111, avoiding dead corners in heat flow coverage.

[0042] The insulated outer tank 1 with a notch 111 serves both as a support and connection between the insulated outer tank 1 and the inner tank 2, and as a heat flow guide, achieving two functions at once. Example 4

[0043] Please see Figures 7-12Based on Example 3, this example provides a detailed explanation of the material feeding mechanism, as follows: The material feeding mechanism includes a feeding box 4 with its bottom connected to the feed inlet 21 and four material feeding rollers 5 rotatably installed inside the feeding box 4. The feeding box 4 is fixed above the insulated outer tank 1 by a bracket (not shown in the figure). The upper part of the feeding box 4 is box-shaped, and the lower part is funnel-shaped. The four material feeding rollers 5 are arranged along a V-shaped path inside the upper part of the feeding box 4, and there is a discharge gap between adjacent material feeding rollers 5 for discharging crushed material that meets the size requirements. One end of each material feeding roller 5 extends through to the outside of the feeding box 4 and is fixedly fitted with a gear 51. The gears 51 on adjacent material feeding rollers 5 mesh with each other. One of the material feeding rollers 5 is linked with the screw conveyor mechanism, which provides a linked drive source for the rotation of the four material feeding rollers 5 when the screw conveyor mechanism is working.

[0044] Each of the crushing rollers 5 has a smooth outer wall, and the crushing effect is achieved by impacting the wet filter cake, which is different from the traditional roller with crushing teeth.

[0045] One of the crushing rollers 5 is fixedly fitted with a first pulley 52 at the end outside the feeding box 4, and a second pulley 53 is fixedly fitted at the end of the auger conveyor rod 3 away from the drive motor 32. The first pulley 52 and the second pulley 53 are nested together with a drive belt 54. The first pulley 52, the second pulley 53 and the drive belt 54 form a pulley group. The first pulley 52 and the second pulley 53 are synchronous pulleys, and the drive belt 54 is a synchronous belt to avoid drive slippage. When the drive motor 32 drives the auger conveyor rod 3 to rotate, the auger conveyor rod 3 drives the second pulley 53 to rotate synchronously. Under the transmission action of the drive belt 54, the crushing roller 5 with the first pulley 52 installed on it can rotate. Under the transmission action of the four gears 51 meshing in pairs, the other three crushing rollers 5 are driven to rotate respectively, thereby realizing the simultaneous rotation of the four crushing rollers 5.

[0046] Furthermore, the four gears 51 mesh sequentially, causing adjacent crushing rollers 5 to rotate in opposite directions, such as... Figure 13 As shown, the crushing roller 5 on the middle side rotates clockwise, and the crushing roller 5 on the outer side of the crushing roller 5 rotates counterclockwise. The crushing roller 5 on the other middle side rotates counterclockwise, and the crushing roller 5 on the outer side of the crushing roller 5 rotates clockwise.

[0047] When the wet filter cake is fed into the feeding box 4, it will come into contact with the rotating crushing roller 5. The mechanism of the two adjacent crushing rollers 5 rotating in opposite directions will produce a shearing and tearing effect when in contact with the wet filter cake, rather than simple compression. When the wet filter cake blocks fall onto the crushing roller 5, they will be instantly grabbed by the roller surface in the opposite direction and pulled in different directions, which can tear and shake the wet filter cake into smaller particles, avoiding the material from rolling synchronously with the roller due to the crushing rollers 5 rotating in the same direction.

[0048] In addition, the four crushing rollers 5 are arranged in a V-shape, forming a crushing channel that gradually narrows from top to bottom. Combined with the different directions of the crushing rollers 5, the material is continuously and irregularly pulled in different directions, forming a crushing effect of jumping, falling and jumping again, ensuring that the lumpy material can be continuously and fully crushed. Material that meets the size requirements falls from between the beam crushing rollers 5 into the feed inlet 21 to realize feeding.

[0049] Compared to traditional rollers with crushing teeth or grooves on their surface, the crushing roller 5 in this embodiment has a smooth roller surface and relies solely on impact and shearing to disperse the material. Its advantage lies in its gentler action, mainly relying on kinetic energy impact and tearing to deagglomerate the material rather than crushing and grinding. This minimizes the amount of fine powder generated by excessive crushing. This design is suitable for subsequent fluidized drying processes (because materials with uniform particle size and low fine powder content have better flowability and fluidization characteristics), avoiding dust and wall adhesion caused by excessive powder during the drying process, and preventing excessive loss and waste of material powder.

[0050] Furthermore, the four meshing gears 51 and the pulley set work together to form a transmission structure, which drives the rotation of the auger conveyor rod 3 as the drive for the four crushing rollers 5. No additional drive source is required. Moreover, the meshing transmission characteristics of the gears 51 not only serve as a transmission component between two adjacent crushing rollers 5, but also enable two adjacent crushing rollers 5 to move in opposite directions. Example 5

[0051] Please see Figure 17 The difference between this embodiment and embodiment 4 is that: Each air inlet 201 is fitted with a core 202. A vertical hole is opened in the middle of the core 202 and distributed along its axis. Several oblique holes are opened in a ring array around the vertical hole on the core 202. The distance between the bottom port of each oblique hole and the bottom port of the vertical hole is smaller than the distance between the top ports of the two. The top of the core 202 is an arc-shaped structure that matches the inner wall of the inner tank 2 and is in a movable fit with the outer edge of the auger conveying rod 3 to avoid obstructing or interfering with the rotation of the auger conveying rod 3.

[0052] The heat flow in the heating chamber is ejected upwards through each inclined hole, forming multiple inclined air jets. The coverage of adjacent inclined air jets complements each other. The heat flow is ejected upwards from the vertical hole, forming a vertical air jet, which makes up for the gas coverage in the middle position, ensuring that the heat flow covers the bottom of the tank without dead corners and in a three-dimensional manner, improving the effect of lifting and fluidizing the material, and enhancing the heat and mass transfer efficiency. Example 6

[0053] Please see Figure 8 , Figure 10 , Figure 12 and Figure 15 The difference between this embodiment and embodiment 5 is as follows: The portion of the discharge port 22 located within the heating clamping cavity has several inlet channels 221 arranged in a ring array around the axis of the discharge port 22. The inlet channels 221 are arranged inclined outwards and upwards to connect the discharge port 22 and the heating clamping cavity.

[0054] The bottom end of the discharge port 22 is connected to the pneumatic conveying system; the pneumatic conveying system includes a first conveying pipe 63, an air inlet box 7, an air outlet box 8, and a second conveying pipe 81; all four crushing rollers 5 are hollow; the air inlet box 7 is fixed on the side of the feeding box 4 away from the gear 51, and the air outlet box 8 is fixed on the other side of the feeding box 4 by a bracket (not marked in the figure); one end of the first conveying pipe 63 is connected to the bottom end of the discharge port 22, and the other end is connected to the air inlet box 7; one end of the second conveying pipe 81 is connected to the air outlet box 8, and the other end is connected to the subsequent process; the air inlet box 7 is rotatably connected to one end of each of the four crushing rollers 5, and the air outlet box 8 is rotatably connected to the other end of each of the four crushing rollers 5. The power source of the pneumatic conveying system adopts existing technology, which will not be described in detail in this embodiment.

[0055] The first conveying pipe 63, the air inlet box 7, the hollow crushing rollers 5, the air outlet box 8, and the second conveying pipe 81 form a pneumatic conveying pipeline. The hot flow in the heating chamber eventually flows into the discharge port 22 from the inlet channel 221, and converges with the hot flow flowing from the inner tank 2 into the discharge port 22. Together with the dried material, it is conveyed to the downstream process along the pneumatic conveying pipeline.

[0056] When the material and heat flow pass through the crushing roller 5, the heat of the material and heat flow is transferred to the crushing roller 5. At the same time, when the wet filter cake and crushed material come into contact with the crushing roller 5, heat exchange also occurs. On the one hand, it can provide a heating environment for the feeding box 4, realize crushing and heating at the same time, reduce the humidity of the material in advance, and prevent the crushed material from clumping again due to high humidity. On the other hand, it can cool down the material and heat flow, which is convenient for subsequent processes.

[0057] The material and heat flow that are just discharged after drying are at a temperature of about 80°C. After passing through the crushing roller 5 for heat exchange, the material temperature gradually decreases due to heat loss during transportation. When all the material is collected, it is mixed with methanol. At this time, the material still retains residual heat, which can play a preheating role in the mixing.

[0058] Furthermore, the multi-channel parallel system employed in this novel purification and hydrolysis method is based on the core process chain of pretreatment, esterification, purification, and hydrolysis. Each key equipment unit is designed as a multi-group parallel channel structure, with each channel sequentially connected to form multiple synchronously operating complete process flows. While ensuring that the operating parameters of each parallel channel strictly match the optimal process conditions of a single channel and guaranteeing product purity and yield, the simultaneous processing of fermentation raw materials through multiple channels increases the material throughput per unit time. This not only maintains the advantages of continuous and low-energy consumption of the original process but also solves the problem of limited single-channel capacity, meeting the needs of large-scale industrial production.

[0059] 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 present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

Claims

1. A novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method, characterized in that: Step 1: the fermentation broth is acid precipitated on line, and then solid-liquid separation and drying are performed to obtain technical grade crude substance of the material shown in formula I; Step 2: the technical grade crude substance of the material shown in formula I is continuously esterified with methanol and water is removed in a rectification system with a strong acid cation exchange resin catalytic section to obtain crude dimethyl octadecanedioate; Step 3: the crude dimethyl octadecanedioate is sequentially subjected to thin film evaporation and short path molecular distillation to obtain high purity material shown in formula II; Step 4: the material shown in formula II is subjected to micro-channel reaction with water, solvent and acid catalyst, continuously hydrolyzed at 120-160℃, 0.5-3.0MPa for 5-30min, and the generated methanol is removed on line, and then the hydrolysis liquid is cooled, acid precipitated, solid-liquid separated and dried to obtain the material shown in formula I with purity ≥99.0%. The crude product of octadecanedioic acid synthesized by fermentation is used as a starting material to generate a substance represented by Formula II by esterification in a rectifying column kettle. The substance represented by Formula II is purified by rectification, and the high-purity substance represented by Formula II is subjected to acid-catalyzed micro-channel hydrolysis to obtain a high-purity substance represented by Formula I. The specific steps include the following: 2.The novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method according to claim 1, characterized in that: the novel purification and hydrolysis method is realized by a multi-channel parallel system; the multi-channel parallel system comprises an on-line acid precipitation tank, a solid-liquid separation unit, a drying unit, a reaction rectification tower with a resin catalytic section, a thin film evaporator, a short path molecular distillation device and a micro-channel reactor which are sequentially connected; the solid-liquid separation unit is a plate and frame filter, and the drying unit is a fluidized dryer. 3.The novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method according to claim 2, characterized in that: the esterification reaction in step 2 is carried out at normal pressure and 50-90℃ for 2-4h, and the esterification reaction distillate is methanol / water azeotrope which is recycled by absorbing water with molecular sieve. 4.The novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method according to claim 1, characterized in that: in step 3, the feeding rate of thin film evaporation is 30-40kg / h, the evaporation rotor speed is 225-270rpm, the operating pressure is 1-10mbar, the heating temperature is 200-220℃, the top fraction temperature is 180-185℃, and the end fraction temperature is >190℃; in step 3, the operating pressure of short path molecular distillation is 0.01-0.1mbar, the heating surface temperature is 150-170℃, the condensing surface temperature is 80-100℃, the distance between the evaporation surface and the condensing surface is <2cm, the feeding speed is 0.5-2kg / h·m², the scraper speed is 80%-95% of the maximum design speed, and the material preheating temperature is 120-140℃. 5.The novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method according to claim 1, characterized in that: the purity of the material shown in formula II after thin film evaporation is >95%, and the purity after short path molecular distillation is >99%. 6.The novel purification and hydrolysis method for synthesizing octadecanedioic acid by fermentation method according to claim 1, characterized in that: the acid catalyst in step 4 is one or more of sulfuric acid, p-toluenesulfonic acid and phosphoric acid, and the usage amount is 0.05-1.0wt% of the mass of the material shown in formula II. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The solvent in step four is one of dioxane, acetic acid, DMF, NMP or a mixture of several thereof, the concentration of the reaction solution is 20-50wt%, the amount of water used is 0.1-1.0wt% of the mass of the substance shown in formula II, the reaction temperature is 110-130℃, and the retention time is 25-30min. 7.The novel purification and hydrolysis method of the fermentation synthesis of octadecanedioic acid according to claim 2, characterized in that: Step one adopts a fluidized dryer, which comprises a heat-insulating outer tank body (1), an inner tank body (2), a spiral conveying mechanism and a hot stream supply system; The heat-insulating outer tank body (1) is fixed outside the inner tank body (2), and a heating clamping cavity is formed between the heat-insulating outer tank body (1) and the inner tank body (2), and the hot stream supply system is used for supplying hot stream into the heating clamping cavity; The inner tank body (2) has a feeding port (21) penetrating upward to the outside of the heat-insulating outer tank body (1) on one side and a discharging port (22) penetrating downward to the outside of the heat-insulating outer tank body (1) on the other side; The spiral conveying mechanism is used for spirally conveying the material from the feeding port (21) side to the discharging port (22) side; A crushed material feeding mechanism is arranged above the heat-insulating outer tank body (1) and connected with the feeding port (21); The crushed material feeding mechanism comprises a feeding box (4) and four crushed material rollers (5) rotatably installed in the feeding box (4), and the bottom of the feeding box (4) is connected with the feeding port (21); The four crushed material rollers (5) are arranged along a V-shaped path, and there is a discharging gap between adjacent two crushed material rollers (5); One end of each crushed material roller (5) penetrates to the outside of the feeding box (4) and is fixedly sleeved with a gear (51), and the gears (51) on adjacent two crushed material rollers (5) are correspondingly meshed; One of the crushed material rollers (5) is connected with the spiral conveying mechanism. 8.The novel purification and hydrolysis method of the fermentation synthesis of octadecanedioic acid according to claim 7, characterized in that: The spiral conveying mechanism comprises an auger conveying rod (3) and a driving motor (32); The auger conveying rod (3) is coaxially and rotatably installed in the inner tank body (2), and the outer edge wall of the auger conveying rod (3) is movably attached to the inner wall of the inner tank body (2); Both ends of the auger conveying rod (3) penetrate to the outside of the heat-insulating outer tank body (1); One side of the heat-insulating outer tank body (1) is fixedly provided with a motor base (31), the driving motor (32) is fixedly installed on the motor base (31), and the output shaft of the driving motor (32) is fixedly connected with the end of the auger conveying rod (3); One end of one of the crushed material rollers (5) located outside the feeding box (4) is fixedly sleeved with a first belt pulley (52); The end of the auger conveying rod (3) away from the driving motor (32) is fixedly sleeved with a second belt pulley (53); The first belt pulley (52) and the second belt pulley (53) are jointly and transmissionally nested with a transmission belt (54). 9.The novel purification and hydrolysis method of the fermentation synthesis of octadecanedioic acid according to claim 8, characterized in that: The hot stream supply system comprises an air blower (6), a heater (61) and an air supply pipeline (62). The air blower (6) and the heater (61) are arranged beside the heat preservation outer tank body (1), and the air outlet end of the air blower (6) is connected with the air inlet end of the heater (61) through the air supply pipeline (601); The air outlet end of the heater (61) is connected with one end of the air supply pipeline (62), the other end of the air supply pipeline (62) is connected with one end of the heat preservation outer tank body (1) away from the driving motor (32), and is communicated with the heating clamp cavity; A plurality of annular support plates (11) are fixedly sleeved on the outer wall of the inner tank body (2) along the length direction at intervals, and the peripheral wall of each annular support plate (11) is fixed with the inner wall of the heat preservation outer tank body (1); Each annular support plate (11) is provided with a notch (111), and the notches (111) on the adjacent two annular support plates (11) are distributed in an up-down staggered manner. A plurality of air inlet holes (201) are arranged on the bottom of the inner tank body (2) along the length direction at intervals.

10. The novel purification and hydrolysis method of the fermentation synthesis of octadecanedioic acid according to claim 7, characterized in that: The part of the discharge port (22) in the heating clamp cavity is arranged with a plurality of inflow channels (221) around the discharge port (22) axis in an annular array, which are used for connecting the discharge port (22) and the heating clamp cavity.

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