Preparation method and application of carbon-based solid acid catalyst
By preparing carbon-based solid acid catalysts from biomass waste, the problems of waste liquid pollution and low efficiency in the traditional diosgenin preparation have been solved, achieving high-yield, low-cost, and green extraction of diosgenin, and the catalyst can be reused.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2026-03-13
AI Technical Summary
Traditional methods for preparing diosgenin generate large amounts of acidic waste liquid, leading to environmental pollution and equipment corrosion, and are also inefficient, failing to meet the growing market demand.
Carbon-based solid acid catalysts are prepared using biomass waste. Sulfonated carbon-based solid acids containing -SO3H groups are prepared through calcination and sulfonation processes for the extraction of diosgenin, avoiding waste liquid discharge and improving yield.
This process achieves a green extraction process with no waste liquid discharge, improves the yield of diosgenin, reduces preparation costs, and allows for catalyst reuse, resulting in significant economic benefits.
Smart Images
Figure CN121648940A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a method for preparing and applying a carbon-based solid acid catalyst, which belongs to the field of biomedicine. Background Technology
[0002] Diosgenin is a plant secondary metabolite and a steroid compound, composed of 27 carbon atoms and a derivative of isosspirol sterane. It is mainly found in plants of the genus *Dioscorea* (such as *Curcuma longa*, *Dioscorea nipponica*, and *Fenugreek*). Due to the presence of the 3β-OH structure, it readily introduces a ketone group at this site, transforming into pregnanediol acetate, androstenedione, 9-hydroxyandrostenedione, etc., which can then be used to synthesize downstream steroid hormone drugs. Therefore, diosgenin is a crucial starting material for the synthesis of steroid hormone drugs; most steroid drugs are obtained through modification and transformation of diosgenin, hence it is also known as the "mother of hormones" and "medicinal gold." Currently, the global annual demand for diosgenin exceeds 4,000 tons and is still increasing at a rate of 8% per year. Furthermore, diosgenin itself has certain pharmacological activity and has shown some efficacy in treating asthma, diabetes, osteoporosis, and arteriosclerosis.
[0003] Steroidal saponins are the main form of diosgenin found in plants. Different sugar groups (mainly rhamnose and glucose) are linked by glycosidic bonds at the C-3 and C-26 positions to form different saponins. Saponins are primarily found in the vascular bundle cell walls of plants, encapsulated by large amounts of lignocellulose and pectin, making them mechanically strong and difficult to break down. Therefore, the key to preparing diosgenin is to first release the saponins from the cell walls, and then hydrolyze them to break the glycosidic bonds to obtain diosgenin.
[0004] The increasing incidence of chronic diseases has led to a continuous increase in market demand for steroid hormone drugs. This increased demand for downstream drugs has also resulted in a surge in demand for diosgenin, a starting material for upstream drug synthesis. In traditional industry, the preparation of diosgenin is typically achieved by treating Dioscorea plants with strong inorganic acids. However, this method often generates large amounts of difficult-to-treat acidic waste liquid, causes severe corrosion to production equipment, and has relatively low efficiency in the preparation of diosgenin.
[0005] Given this situation, developing a green, efficient, and convenient method for preparing diosgenin is a key research focus. Solid acids, due to their ease of separation from the reaction system and non-corrosiveness to reaction equipment, are widely used in alkylation, esterification, biodiesel / glycerol acetylation, polymerization, and other reactions. Summary of the Invention
[0006] The purpose of this application is to provide a method for extracting diosgenin that produces no waste liquid, allows for the complete recycling of the alcohol solvent and solid acid catalyst used, achieves higher yield, is more environmentally friendly, and has higher economic benefits. Furthermore, the method utilizes carbon-based solid acid prepared from biomass waste, thereby reducing the preparation cost of solid acid and providing a new approach for the conversion and utilization of biomass waste.
[0007] Low-cost and environmentally friendly biomass-based carbon-based solid acids have attracted widespread attention for the high-value utilization of biomass waste due to their simple preparation process and abundant precursor resources required for synthesis. Among them, sulfonated carbon-based solid acids containing the -SO3H group are a novel class of metal-free solid protic acids, possessing a unique carbon structure and properties comparable to concentrated sulfuric acid. Acidic (-H0 = 8-11). These carbon supports are covalently linked via C-PhSO3H or C-SO3H with -SO3H groups. Due to their good adaptability in various solvents, unique surface chemistry, high chemical and thermal stability, and customizable pore structure, they are considered a good alternative to H2SO4. They are significantly superior to traditional solid acid catalysts (cation exchange resins, sulfuric acid oxides, and acidic zeolites) in catalyzing biomass conversion, especially in macromolecular catalysis.
[0008] According to one aspect of this application, a method for preparing a carbon-based solid acid catalyst is provided, the method comprising the following steps:
[0009] S1: Under an inactive atmosphere, biomass residue is calcined, acid-washed, and dried to obtain a carbon support;
[0010] S2: Sulfonate and dry the mixture containing carbon support, chlorosulfonic acid and solvent to obtain the carbon-based solid acid catalyst.
[0011] Optionally, in step S1, the biomass residue is selected from at least one of corn stalks, ginger residue, and rice husks.
[0012] Optionally, the particle size of the biomass residue is 0.001 to 0.075 mm.
[0013] Optionally, the calcination temperature is 600–900°C, and the calcination time is 4–6 hours.
[0014] Optionally, the acid used in the pickling process is hydrochloric acid.
[0015] Optionally, the inactive atmosphere is selected from at least one of nitrogen, argon, and helium.
[0016] Optionally, in step S2, the solvent is selected from at least one of dichloromethane, chloroform, and acetic acid.
[0017] Optionally, the mass-to-volume ratio of the carbon support to the solvent is 1:15-30 g / mL.
[0018] Optionally, the mass-to-volume ratio of the carbon support to the chlorosulfonic acid is 1:10-20 g / mL.
[0019] Optionally, the sulfonation temperature is 0–5°C, and the sulfonation time is 2–6 hours.
[0020] Optionally, the sulfonation temperature is independently selected from any value of 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, or a range between any two of the above.
[0021] Optionally, the sulfonation time is independently selected from any value of 2h, 3h, 4h, 5h, 6h or a range between any two of the above.
[0022] Optionally, the temperatures of drying I and drying II are independently selected from 40 to 50°C, and the times of drying I and drying II are independently selected from 8 to 12 hours.
[0023] According to another aspect of this application, a carbon-based solid acid catalyst prepared by the preparation method described above is provided.
[0024] According to another aspect of this application, the application of the above-described carbon-based solid acid catalyst in the preparation of diosgenin is provided, wherein the method for preparing diosgenin includes the following steps:
[0025] (1) Extract the turmeric powder by reflux with an alcohol solvent, dry it to obtain crude saponin mother liquor;
[0026] (2) In a closed reactor, a mixture containing crude saponin mother liquor and carbon-based solid acid catalyst is reacted to obtain diosgenin.
[0027] Optionally, in step (2), the volume-to-mass ratio of the crude saponin mother liquor to the carbon-based solid acid catalyst is (2-5 mL): (0.025-0.125) g.
[0028] Optionally, in step (2), the reaction temperature is 100-160°C and the reaction time is 2-7 hours.
[0029] Optionally, in step (2), the carbon-based solid acid catalyst is recovered by filtration after the reaction is completed.
[0030] Optionally, in step (1), the alcohol solvent is selected from at least one of methanol, ethanol, isopropanol, n-propanol, n-butanol, and isobutanol.
[0031] Optionally, the solid-liquid ratio of the turmeric powder to the alcohol solvent is 1:10-20 g / mL.
[0032] Optionally, in step (1), the reflux extraction temperature is 90-120°C, and the reflux extraction time is 6-10 hours.
[0033] Optionally, the reflux extraction temperature is independently selected from any value of 90°C, 100°C, 110°C, 120°C, or a range between any two of the above.
[0034] Optionally, the reflux extraction time is independently selected from any value among 6h, 7h, 8h, 9h, and 10h, or a range between any two of the above.
[0035] Optionally, the temperature of the drying process III is 40–55°C, and the drying time is 8–12 hours.
[0036] Optionally, in step (1), the alcohol solvent is recovered after the reflux extraction is completed.
[0037] Optionally, the particle size of the turmeric powder is less than 0.075 mm.
[0038] As an optional implementation, this application is achieved through the following technical solution:
[0039] (1) Use physical methods to crush turmeric into particles, and after sieving, obtain turmeric powder.
[0040] (2) Crude saponins were extracted from the turmeric powder obtained in step (1) by heating and refluxing with an alcohol solvent. After the reflux was completed, the reaction solution was filtered and the alcohol solvent was recovered by vacuum distillation. The crude saponins were dried under vacuum overnight and then dissolved and diluted with methanol to prepare a crude saponin mother liquor.
[0041] (3) After the biomass residue is crushed into powder, it is placed in an Al2O3 quartz boat and calcined in a tube furnace to obtain a carbon carrier, which is then sulfonated with chlorosulfonic acid to obtain a carbon-based solid acid.
[0042] (4) Use a pipette to transfer the crude saponin solution obtained in step (2) to the reaction vessel, add the carbon-based solid acid catalyst obtained in step (3), and then put it into an oil bath for heating and pressurization reaction. After the reaction is completed, filter to recover the solid acid catalyst, and after the reaction solution is diluted with methanol, the yield of diosgenin is determined by high performance liquid chromatography.
[0043] As one specific implementation method, the method includes:
[0044] Fresh ginger rhizomes were washed, dried, and then crushed using a high-speed crusher. After sieving, refined ginger powder was obtained. A certain amount of ginger powder was weighed and transferred to a round-bottom flask. A certain amount of alcohol solvent was added, and the flask was heated under reflux in an oil bath. After reflux, the reaction solution was filtered. The alcohol solvent was recovered by vacuum distillation. The crude saponins obtained were dried under vacuum overnight and then dissolved in methanol and diluted to a volumetric flask of 100 mL.
[0045] A precise amount of crude saponin mother liquor was transferred using a pipette to a 15 mL stainless steel reaction vessel equipped with a magnetic stirrup. A certain amount of the prepared solid acid catalyst was added, and the reaction vessel was sealed. The gas inside the reaction vessel was purged five times with high-purity nitrogen. Once the oil bath reached the specified temperature, the reaction vessel was placed in the oil bath, and timing was started. After the reaction was complete, the reaction vessel was immediately placed in an ice-water bath to cool, and solid-liquid separation was performed using a Buchner funnel. The resulting reaction solution was transferred to a 25 mL volumetric flask and diluted to volume with methanol. After filtration through a membrane filter, the solution was analyzed using high-performance liquid chromatography (HPLC), and the yield of diosgenin was calculated.
[0046] The beneficial effects that this application can produce include:
[0047] This application provides a method for extracting crude saponin powder using an alcohol solvent, and then using a carbon-based solid acid catalyst prepared from biomass waste to catalyze the alcoholysis of the crude saponin powder to prepare diosgenin. The entire process generates no waste liquid, avoiding the environmental pollution and equipment corrosion problems caused by the use of inorganic strong acids such as sulfuric acid and hydrochloric acid in traditional industrial processes. Furthermore, the reusability of the solid acid catalyst greatly increases the economic benefits of the entire process. Preparing carbon-based solid acids from biomass waste reduces the cost of solid acid production and provides a new approach for the conversion of other biomass wastes. Attached Figure Description
[0048] Figure 1 The image shows the FT-IR spectrum of the carbon-based solid acid prepared in Example 1 of this application.
[0049] Figure 2 The XPS spectra of the carbon-based solid acid prepared in Example 1 of this application are shown in Figure (Figure (a) is the full XPS spectrum before and after sulfonation, Figure (b) is the C1s spectrum, Figure (c) is the O1s spectrum, and Figure (d) is the S2p spectrum).
[0050] Figure 3 This is the external standard working curve of diosgenin in Example 3 of this application. Detailed Implementation
[0051] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0052] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0053] This application utilizes Fourier transform infrared spectroscopy to characterize the functional group structure on the sample surface. Sample preparation was performed using the KBr pellet method. The sample was mixed with potassium bromide (m:m = 1:100), ground clockwise in an agate mortar until no particles remained. The ground powder was then poured into a mold and pressed into translucent sheets using a pellet press. The instrument was set to transmission mode, with wavenumbers ranging from 400 to 4000 cm⁻¹. -1 Signals are collected within a certain range.
[0054] The elemental composition and chemical valence state of the prepared carbon-based solid acid were detected by X-ray photoelectron spectroscopy, using monochromatic Al Kα radiation as the excitation source, and the elements were corrected according to the peak shifts of C1s, O1s, and S2p.
[0055] Example 1: Preparation of carbon-based solid acids
[0056] Accurately weigh 5.0 g of the remaining ginger residue after diosgenin extraction, with a particle size of 0.02 mm, and transfer it to an Al₂O₃ quartz boat placed in a tube furnace. The tube furnace was set with a heating rate of 5 °C / min, a calcination temperature of 800 °C, and a calcination time of 2 h. The calcination process was carried out under a nitrogen atmosphere with a gas flow rate of 20 mL / min. After calcination, the resulting solid was acid-washed with 1 M HCl, then washed with water until neutral, and dried in an oven at 105 °C for 10 h to obtain the carbon support.
[0057] Accurately weigh 2.0 g of the calcined and activated carbon support and ultrasonically disperse it in 30 mL of dichloromethane. Use a pipette to transfer 1.0 mL of chlorosulfonic acid to 30 mL of dichloromethane to prepare a chlorosulfonic acid / dichloromethane solution. Under stirring conditions in an ice-water bath, slowly add the chlorosulfonic acid solution dropwise to the dichloromethane suspension of the carbon support and sulfonate for 4 h. After filtration, wash with dichloromethane and ethanol until neutral, and dry in an oven at 105 °C overnight to obtain a carbon-based solid acid catalyst.
[0058] Depend on Figure 1 and Figure 2 It can be seen that the sulfonation process successfully loaded the -SO3H group onto the carbon support, and the loading was carried out in a covalent manner of C-SO3H.
[0059] like Figure 2 As shown, the chemical states of C, O, and S in C-800 and C-800-SO3H were analyzed using XPS. Figure 2 As shown in (a), in the XPS full spectrum, the intensity of the S2p peak of C-800-SO3H is significantly stronger than that of C-800, indicating that an S-containing group is grafted onto the surface of the C-800 support. Figure 2(b) High-resolution XPS spectra of C1s for C-800 and C-800-SO3H. Four fitting peaks are observed in C-800: C=C (284.8 eV), CC (285.7 eV), CO (286.3 eV), and π-π* (293.6 eV). Similarly, four fitting peaks are observed in C-800-SO3H: C=C (284.8 eV), CC (285.7 eV), CO (286.3 eV), and OC=O (289.3 eV). The disappearance of the π-π* fitting peak indicates that chlorosulfonic acid altered the carbon framework layer of the original carbon support, while the appearance of the OC=O fitting peak suggests that chlorosulfonic acid may have oxidized -OH to -COOH during the sulfonation process. For the O1s energy level ( Figure 2 (c) In addition to the presence of C=O (531.6 eV) and CO (533.4 eV), a fitting peak of -SO3H (532.2 eV) also appeared in C-800-SO3H, indicating that the -SO3H group was successfully loaded onto the C-800 support. In the S2p high-resolution XPS spectrum ( Figure 2 (d) has two fitting peaks at 167.9 eV and 169.1 eV, corresponding to S2p3 / 2 and S2p1 / 2, respectively.
[0060] Example 2: Preparation of carbon-based solid acids
[0061] Accurately weigh 5.0 g of corn stalk powder (0.01 mm particle size) and transfer it to an Al₂O₃ quartz boat placed in a tube furnace. The tube furnace was set to a heating rate of 5 °C / min, a calcination temperature of 750 °C, and a calcination time of 2 h. The calcination process was carried out under a nitrogen atmosphere at a gas flow rate of 20 mL / min. After calcination, the resulting solid was acid-washed with 1 M HCl, then washed with water until neutral, and dried in a 105 °C oven for 12 h to obtain the carbon support.
[0062] Accurately weigh 2.0 g of the calcined and activated carbon support and ultrasonically disperse it in 30 mL of dichloromethane. Use a pipette to transfer 1.0 mL of chlorosulfonic acid to 30 mL of dichloromethane to prepare a chlorosulfonic acid / dichloromethane solution. Under stirring conditions in an ice-water bath, slowly add the chlorosulfonic acid solution dropwise to the dichloromethane suspension of the carbon support and sulfonate for 4 h. After filtration, wash with dichloromethane and ethanol until neutral, and dry in an oven at 105 °C overnight to obtain a carbon-based solid acid catalyst.
[0063] Example 3: Preparation of diosgenin from crude saponins via carbon-based solid acid-catalyzed alcoholysis
[0064] Accurately weigh 5.0 g of washed, dried, and pulverized turmeric powder (particle size 0.001 mm), add 75 mL of methanol, and reflux at 100 °C for 6 h. Collect the remaining solid after filtration, and repeat the above steps for a second extraction. Combine the reaction solutions from the two extractions, distill under reduced pressure to obtain crude saponins, and dry under vacuum at 40 °C overnight for later use. Dissolve the crude saponins in methanol and dilute to 100 mL in a volumetric flask to prepare a crude saponin mother liquor.
[0065] Accurately transfer 5 mL of crude saponin mother liquor to a 15 mL stainless steel reactor equipped with a magnetic stirrup using a pipette. Add 0.1 g of the carbon-based solid acid catalyst prepared in Example 1 and seal the reactor. Replace the gas inside the reactor five times with high-purity nitrogen to purge the air. Once the oil bath reaches the specified temperature, place the reactor in the oil bath and start timing. Set the reaction temperature to 140 °C, the reaction time to 6 h, and the stirring speed to 500 rpm / min. After the reaction is complete, immediately place the reactor in an ice-water bath to cool it down, and use a Buchner funnel for solid-liquid separation. Transfer the obtained reaction solution to a 25 mL volumetric flask and dilute to volume with methanol. After filtration through a filter membrane, analyze using high-performance liquid chromatography (HPLC). Calculate the yield of diosgenin using the external standard curve method (external standard curve shown in Figure 1). Figure 3 As shown in the figure, the diosgenin yield was 3.87%.
[0066] Example 4: Preparation of diosgenin from crude saponins via carbon-based solid acid-catalyzed alcoholysis
[0067] Accurately weigh 5.0 g of washed, dried, and pulverized turmeric powder (particle size 0.05 mm), add 75 mL of methanol, and reflux at 100 °C for 6 h. Collect the remaining solid after filtration, and repeat the above steps for a second extraction. Combine the reaction solutions from the two extractions, distill under reduced pressure to obtain crude saponins, and dry under vacuum at 40 °C overnight for later use. Dissolve the crude saponins in methanol and dilute to 100 mL in a volumetric flask to prepare the crude saponin mother liquor.
[0068] Accurately transfer 5 mL of crude saponin mother liquor to a 15 mL stainless steel reactor equipped with a magnetic stirrup using a pipette. Add 0.05 g of the carbon-based solid acid catalyst prepared in Example 2, and seal the reactor. Replace the gas inside the reactor five times with high-purity nitrogen to purge the air. Once the oil bath reaches the specified temperature, place the reactor in the oil bath and start timing. Set the reaction temperature to 140 °C, the reaction time to 6 h, and the stirring speed to 500 rpm / min. After the reaction is complete, immediately place the reactor in an ice-water bath to cool, and perform solid-liquid separation using a Buchner funnel. Transfer the obtained reaction solution to a 25 mL volumetric flask and dilute to volume with methanol. After filtration through a filter membrane, analyze using high-performance liquid chromatography (HPLC). Calculate the yield of diosgenin using the external standard curve method; the yield of diosgenin was 2.83%.
[0069] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing a carbon-based solid acid catalyst, characterized in that, The preparation method includes the following steps: S1: Under an inactive atmosphere, biomass residue is calcined, acid-washed, and dried to obtain a carbon support; S2: Sulfonate and dry the mixture containing carbon support, chlorosulfonic acid and solvent to obtain the carbon-based solid acid catalyst.
2. The preparation method according to claim 1, characterized in that, In step S1, the biomass residue is selected from at least one of corn stalks, ginger residue, and rice husks; Preferably, the particle size of the biomass residue is 0.001–0.075 mm; Preferably, the calcination temperature is 600–900°C, and the calcination time is 4–6 hours; Preferably, the acid used in the pickling is hydrochloric acid; Preferably, the inactive atmosphere is selected from at least one of nitrogen, argon, and helium.
3. The preparation method according to claim 1, characterized in that, In step S2, the solvent is selected from at least one of dichloromethane, chloroform, and acetic acid; Preferably, the mass-to-volume ratio of the carbon support to the solvent is 1:15-30 g / mL; Preferably, the mass-to-volume ratio of the carbon support to the chlorosulfonic acid is 1:10-20 g / mL; Preferably, the sulfonation temperature is 0–5°C, and the sulfonation time is 2–6 hours; Preferably, the temperatures of drying I and drying II are independently selected from 40 to 50°C, and the times of drying I and drying II are independently selected from 8 to 12 hours.
4. The carbon-based solid acid catalyst prepared by the preparation method according to any one of claims 1 to 3.
5. The application of the carbon-based solid acid catalyst according to claim 4 in the preparation of diosgenin, characterized in that, The method for preparing diosgenin includes the following steps: (1) Extract the turmeric powder by reflux with an alcohol solvent, dry it to obtain crude saponin mother liquor; (2) In a closed reactor, a mixture containing crude saponin mother liquor and carbon-based solid acid catalyst is reacted to obtain diosgenin.
6. The application according to claim 5, characterized in that, In step (2), the volume-to-mass ratio of the crude saponin mother liquor to the carbon-based solid acid catalyst is (2-5 mL): (0.025-0.125) g.
7. The application according to claim 5, characterized in that, In step (2), the reaction temperature is 100-160°C and the reaction time is 2-7 hours. Preferably, in step (2), the carbon-based solid acid catalyst is recovered by filtration after the reaction is completed.
8. The application according to claim 5, characterized in that, In step (1), the alcohol solvent is selected from at least one of methanol, ethanol, isopropanol, n-propanol, n-butanol, and isobutanol; Preferably, the solid-liquid ratio of the turmeric powder to the alcohol solvent is 1:10-20 g / mL.
9. The application according to claim 5, characterized in that, In step (1), the reflux extraction temperature is 90-120℃ and the reflux extraction time is 6-10h; Preferably, the temperature of the drying process III is 40–55°C, and the drying time is 8–12 hours.
10. The application according to claim 5, characterized in that, In step (1), the alcohol solvent is recovered after the reflux extraction is completed; Preferably, the particle size of the turmeric powder is less than 0.075 mm.