Process for the catalytic conversion of xylose to diols
The preparation of 1,2-propanediol from xylose using the metal oxide catalyst NiZn@TiO2 in a high-pressure autoclave solves the problem of high energy consumption and high cost in the traditional method, achieving efficient and economical conversion of biomass into diol. The catalyst is readily available and has good stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2023-12-29
- Publication Date
- 2026-08-04
AI Technical Summary
In existing technologies, traditional 1,2-propanediol production processes use petroleum or coal resources as raw materials, which have problems such as high pollution, high cost and high energy consumption. However, the production of 1,2-propanediol through biomass is more green, economical and highly renewable. However, existing methods have not yet effectively solved the technical problem of efficiently converting xylose into diol.
Using the metal oxide catalyst NiZn@TiO2, ethylene glycol, 1,2-propanediol, and 1,2-butanediol were prepared by mixing NiZn@TiO2 with xylose and deionized water in a high-pressure reactor and reacting at 200-270℃ for 1-5 h using exogenous hydrogen as a hydrogen donor. The reaction conditions included a hydrogen pressure of 1-10 MPa and a temperature of 200-250℃. The catalyst was prepared from Ni(NO3)2·6H2O, Zn(NO3)2·6H2O, and TiO2, and was used after calcination and reduction treatment.
The method achieves efficient catalytic conversion of xylose into diols with high yield and low preparation cost. The catalyst is readily available, the reaction system is safe, the product separation is simple, and the catalyst has good stability and reusability.
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Figure CN117820077B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fine chemical technology, specifically relating to a method for preparing diols from xylose via catalytic conversion, and more specifically to a method for preparing diols from xylose via a metal oxide catalyst. Background Technology
[0002] With the continuous exploitation and extensive use of fossil resources, the deterioration of the ecological environment and the depletion of fossil resources are becoming increasingly apparent, making the development of renewable and clean energy to replace traditional energy sources an inevitable trend. Among numerous renewable resources, biomass resources have the advantages of wide availability, abundant reserves, and low price. It is the only renewable organic carbon resource in nature and can be converted into various fuels and high-value-added chemicals. Hemicellulose-based biomass is the second most abundant natural carbohydrate in biomass, including xylose, arabinose, and galactose. Hemicellulose can be depolymerized to obtain xylose, xylitol, and other pentoses, as well as various phenolic chemicals. These chemicals can be catalytically converted to prepare high-value-added platform chemicals, such as ethylene glycol, 1,2-propanediol, and 1,2-butanediol, which are among the most promising bio-based platform compounds. Ethylene glycol is a high-value-added chemical raw material, used as an antifreeze and coolant. 1,2-Propanediol, as an important value-added chemical, is widely used in pharmaceuticals, food, and tobacco industries. Traditional 1,2-propanediol production processes use petroleum or coal resources as raw materials, resulting in high pollution, high costs, and high energy consumption. In contrast, biomass-based 1,2-propanediol production is greener, more economical, and renewable, making it a research hotspot and focus. 1,2-Butanediol, due to its low freezing point and low viscosity, has important applications in the modification of polyesters and polyurethanes, as well as in the preparation of PVC films with low volatility, alkali resistance, migration resistance, and solvent resistance. It can also be used in pharmaceuticals, food additives, fuels, and solvents. Summary of the Invention
[0003] The purpose of this invention is to overcome the defects of the prior art and provide a method for preparing diols from xylose by catalytic conversion.
[0004] To achieve the above objectives, the technical solution of the present invention is as follows:
[0005] A method for preparing diols from xylose via catalytic conversion specifically includes: loading xylose, a catalyst, and a solvent into a high-pressure reactor, mixing them thoroughly, sealing the reactor, and carrying out a closed reaction at 200-270°C for 1-5 hours with a stirring rate of 800 rpm. The mixture is then cooled to room temperature to obtain the diol. The cooled solution is detected by liquid chromatography and gas chromatography-mass spectrometry. The diols include ethylene glycol, 1,2-propanediol, and 1,2-butanediol.
[0006] The preparation method of the above catalyst includes the following steps: Dissolve metal nitrate solutions Ni(NO3)2·6H2O and Zn(NO3)2·6H2O in an appropriate amount of deionized water at room temperature, then add an appropriate amount of nano-TiO2 and sonicate for 30-60 min. Subsequently, under magnetic stirring, slowly add a precipitant Na2CO3 solution to adjust the pH value of the mother liquor to the required value (pH 8). Then, continuously stir and age at 353 K for 3 h. Separate the precipitate from the mother liquor using a vacuum filtration device, and thoroughly wash the resulting filter cake with deionized water. Dry the washed precipitate at 393 K for 12 h, cool to room temperature, grind thoroughly in a mortar and pestle, and pass through a 100-mesh sieve. Then, calcine in air at 673 K for 4 h. Finally, reduce the calcined catalyst in a tube furnace at 773 K and 5% H2–N2 (v / v) for 5 h. Before exposure to air, the catalyst is passivated by purging with 1% O2–N2 (v / v) at room temperature for 5 h.
[0007] In a preferred embodiment of the present invention, the mass ratio of the catalyst to xylose is 0.05-0.25g:0.5g, preferably 0.15g:0.5g; the ratio of xylose to deionized water solvent is 3.3mmol:30mL; the reaction temperature is 200-250℃, preferably 230-250℃; the reaction time is 1-5h, preferably 2-3h; and the hydrogen pressure in the reaction system is 1-10MPa, preferably 6-8MPa.
[0008] In a preferred embodiment of the present invention, the calcination operation in the tubular furnace is carried out by calcining at 400-500°C for 4-5 hours in the tubular furnace, preferably calcining at 500°C for 5 hours in a tubular furnace with a volume fraction of 5% H2–N2.
[0009] In a preferred embodiment of the present invention, the active nickel precursor, the active zinc precursor and the TiO2 particles are in a molar ratio of 3:8:4 based on Ni, Zn and TiO2.
[0010] In a preferred embodiment of the present invention, the active nickel precursor is Ni(NO3)2·6H2O; and the active zinc precursor is Zn(NO3)2·6H2O.
[0011] The beneficial effects of this invention are:
[0012] 1. The materials used in this invention are simple and readily available, the preparation method is simple, the preparation cost is low, and the economy is strong.
[0013] 2. This invention uses exogenous hydrogen as a hydrogen donor and deionized water as a solvent, without the need for other organic solvents. The reaction system is relatively simple and safe, which is beneficial for the separation and purification of the product. Attached Figure Description
[0014] Figure 1 XRD patterns of NiZn@TiO2 catalysts with different metal ratios. Detailed Implementation
[0015] The invention is further illustrated with examples. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products. Specific implementation examples are as follows:
[0016] Examples 1-10
[0017] Accurately weigh 0.012 mol Ni(NO3)2·6H2O and 0.032 mol Zn(NO3)2·6H2O and dissolve them in 20 mL of deionized water at room temperature. Then, weigh 0.016 mol TiO2 particles and disperse them in the mixed solution, and sonicate for 30 min. Subsequently, under magnetic stirring, slowly add Na2CO3 precipitant solution to adjust the pH of the mother liquor to the required value (pH 8). Then, age the solution at 353 K with continuous stirring for 3 h. Separate the precipitate from the mother liquor using a vacuum filter and thoroughly wash the resulting filter cake with deionized water. Dry the washed precipitate at 393 K for 12 h, cool it to room temperature, grind it thoroughly in a mortar and pestle, and pass it through a 100-mesh sieve. Then, calcine it in air at 673 K for 4 h. Finally, reduce the calcined catalyst in a tube furnace at 773 K and 5% H2–N2 (v / v) for 5 h. Before being exposed to air, the catalyst was passivated by purging with 1% O2–N2 at room temperature for 5 hours to obtain the corresponding catalyst, which was then stored in a desiccator for later use.
[0018] Add 0.5g xylose and 30mL deionized water to a 100mL high-pressure reactor, then add 0.15g catalyst (NiZn@TiO2, with a molar ratio of active metals Ni, Zn, and TiO2 of 3:8:4). Replace the air in the reactor with nitrogen three to four times, then seal the reactor and stir at 800rpm. Heat to 245℃ and maintain at 1-10MPaH2 pressure for 2h. After the reaction is completed and cooled to room temperature, separate the reaction mixture, take the supernatant, and prepare standard solutions of xylose, glycol, etc. Quantitative analysis is performed using liquid chromatography, and qualitative analysis is performed using gas chromatography-mass spectrometry. The results are listed in Table 1, serial numbers 1-10.
[0019] The effect of hydrogen pressure on catalytic activity was investigated. At 245℃, a reaction time of 2 h, and a hydrogen pressure of 6 MPa, the xylose conversion rate was 100%, and the diol yield was 64.18%. When the hydrogen pressure was increased to 8 MPa, the diol conversion rate remained at 100%, and the diol yield increased to 69.8%. This indicates that increasing the hydrogen pressure improves the catalytic efficiency. However, when the hydrogen pressure was increased to 10 MPa at 245℃, the diol yield dropped to a low of 64.39%.
[0020] Examples 11-16
[0021] The corresponding catalysts were prepared according to the methods in Examples 1-10 for later use.
[0022] Add 0.5g xylose and 30mL deionized water to a 100mL high-pressure reactor, then add 0.15g catalyst (NiZn@TiO2, with a molar ratio of active metals Ni, Zn, and TiO2 of 3:8:4). After replacing the air in the reactor with nitrogen three to four times, seal the reactor and stir at 800rpm. Under a hydrogen pressure of 8MPa H2, react for 2 hours at temperatures of 265, 255, 235, 225, 215, and 205℃, respectively. After the reaction is completed and cooled to room temperature, separate the reaction mixture, take the supernatant, and prepare standard solutions of xylose, glycol, etc. Quantitative analysis is performed using liquid chromatography, and qualitative analysis is performed using gas chromatography-mass spectrometry. The results are listed in Table 1, serial numbers 11-16.
[0023] The effect of reaction temperature on catalytic activity was investigated.
[0024] Examples 17-23
[0025] The corresponding catalysts were prepared according to the methods in Examples 1-10 for later use.
[0026] Add 0.5g xylose and 30mL deionized water to a 100mL high-pressure reactor, then add 0.15g catalyst (NiZn@TiO2, with a molar ratio of active metals Ni, Zn, and TiO2 of 3:8:4). After replacing the air in the reactor with nitrogen three to four times, seal the reactor and stir at 800rpm. Heat to 255℃ under 8MPa H2 hydrogen pressure and maintain for 5, 4, 3, 2.5, 1.5, 1, and 0.5h respectively. After the reaction is completed and cooled to room temperature, separate the reaction mixture, take the supernatant, and prepare standard solutions of xylose, glycol, etc. Quantitative analysis is performed using liquid chromatography, and qualitative analysis is performed using gas chromatography-mass spectrometry. The results are listed in Table 1, serial numbers 17-23.
[0027] The effect of reaction time on catalytic activity was investigated.
[0028] Examples 24-27
[0029] The corresponding catalysts were prepared according to the methods in Examples 1-10 for later use.
[0030] Add 0.5 g xylose and 30 mL deionized water to a 100 mL high-pressure reactor, then add 0.25, 0.2, 0.1, and 0.05 g of catalyst (NiZn@TiO2, with a molar ratio of active metals Ni, Zn, and TiO2 of 3:8:4), respectively. After purging the reactor with nitrogen three to four times, seal the reactor and stir at 800 rpm. Heat to 255 °C under 8 MPa H2 hydrogen pressure and maintain for 2 h. After the reaction is completed and cooled to room temperature, separate the reaction mixture, take the supernatant, and prepare standard solutions of xylose, glycol, etc. Quantitative analysis is performed using liquid chromatography, and qualitative analysis is performed using gas chromatography-mass spectrometry. The results are listed in Table 1, serial numbers 24-27.
[0031] The effect of catalyst dosage on catalytic activity was investigated.
[0032] Examples 28-33
[0033] Accurately weigh 0.008 and 0.016 mol Ni(NO3)2·6H2O and 0.028 and 0.036 mol Zn(NO3)2·6H2O, respectively, and dissolve them in 20 mL of deionized water at room temperature. Then, weigh 0.012 and 0.020 mol TiO2 particles, respectively, and disperse them in the mixed solution, followed by sonication for 30 min. Subsequently, under magnetic stirring, a Na2CO3 precipitant solution was slowly added dropwise to adjust the pH of the mother liquor to the required value (pH 8). The solution was then continuously stirred and aged at 353 K for 3 h. The precipitate was then separated from the mother liquor using a vacuum filtration device, and the resulting filter cake was thoroughly washed with deionized water. The washed precipitate was then dried at 393 K for 12 h, cooled to room temperature, thoroughly ground in a mortar, and passed through a 100-mesh sieve. Finally, it was calcined in air at 673 K for 4 h. Finally, the calcined catalyst was reduced in a tube furnace at 773 K and 5% H2–N2 (v / v) for 5 h. Before exposure to air, the catalyst was passivated by purging with 1% O2–N2 (v / v) at room temperature for 5 h, thus obtaining the corresponding NiZn@TiO2 catalyst (by adjusting the amount of Ni(NO3)2·6H2O and Zn(NO3)2·6H2O added, catalysts with molar ratios of active metals Ni, Zn, and Ti of 4:8:4, 2:8:4, 3:9:4, 3:7:4, 3:8:5, and 3:8:3 were prepared).
[0034] Add 0.5g xylose and 30mL deionized water to a 100mL high-pressure reactor, then add 0.15g catalyst. Replace the air in the reactor with nitrogen three to four times, then seal the reactor and stir at 800rpm. Heat to 255℃ under 8MPa H2 hydrogen pressure and maintain for 2h. After the reaction is completed and cooled to room temperature, separate the reaction mixture, take the supernatant, and prepare standard solutions of xylose, glycol, etc. Quantitative analysis is performed using liquid chromatography, and qualitative analysis is performed using gas chromatography-mass spectrometry. The results are listed in Table 1, serial numbers 28-33.
[0035] The effect of different metal molar ratios on the catalytic activity of catalysts was investigated.
[0036] Examples 34-39
[0037] Ni3Zn8O x For example: Accurately weigh 0.012 mol of Ni(NO3)2·6H2O and 0.032 mol of Zn(NO3)2·6H2O, dissolve them in 100 mL of deionized water at room temperature, and add 0 TiO2 particles. Sonicate for 30 min. Then, under magnetic stirring, slowly add a Na2CO3 precipitant solution to adjust the pH of the mother liquor to the required value (pH 8). Then, continuously stir and age at 353 K for 3 h. Separate the precipitate from the mother liquor using a vacuum filtration device, and thoroughly wash the resulting filter cake with deionized water. Dry the washed precipitate at 393 K for 12 h, cool to room temperature, grind thoroughly in a mortar and pestle, and pass through a 100-mesh sieve. Then, calcine in air at 673 K for 4 h. Finally, reduce the calcined catalyst in a tube furnace at 773 K and 5% H2–N2 (v / v) for 5 h. Before exposure to air, the catalyst was passivated by purging with 1% O2–N2 by volume for 5 h at room temperature to obtain the corresponding NiZnO. x catalyst.
[0038] Taking Ni@TiO2 (3:4) as an example: 0.012 mol of Ni(NO3)2·6H2O was accurately weighed and dissolved in 100 mL of deionized water at room temperature. Then, 0.016 mol of TiO2 particles were weighed and dispersed in the prepared solution, and sonicated for 30 min. Subsequently, under magnetic stirring, a Na2CO3 precipitant solution was slowly added dropwise to adjust the pH value of the mother liquor to the required value (pH 8). The solution was then continuously stirred and aged at 353 K for 3 h. The precipitate was then separated from the mother liquor using a vacuum filtration device, and the resulting filter cake was thoroughly washed with deionized water. The washed precipitate was then dried at 393 K for 12 h, cooled to room temperature, thoroughly ground in a mortar, and passed through a 100-mesh sieve. Finally, the calcined catalyst was calcined in air at 673 K for 4 h. Finally, the calcined catalyst was reduced in a tube furnace at 773 K and 5% H2–N2 (v / v) for 5 h. Before exposure to air, the catalyst was passivated by purging with 1% O2–N2 by volume for 5 h at room temperature to obtain the corresponding NiZnO. x catalyst.
[0039] Taking ZnO@TiO2 (2:1) as an example: 0.032 mol of Zn(NO3)2·6H2O was accurately weighed and dissolved in 100 mL of deionized water at room temperature. Then, 0.016 mol of TiO2 particles were weighed and dispersed in the prepared solution, and sonicated for 30 min. Subsequently, under magnetic stirring, a Na2CO3 precipitant solution was slowly added dropwise to adjust the pH value of the mother liquor to the required value (pH 8). The solution was then continuously stirred and aged at 353 K for 3 h. The precipitate was then separated from the mother liquor using a vacuum filtration device, and the resulting filter cake was thoroughly washed with deionized water. The washed precipitate was then dried at 393 K for 12 h, cooled to room temperature, thoroughly ground in a mortar, and passed through a 100-mesh sieve. Finally, the calcined catalyst was calcined in air at 673 K for 4 h. Finally, the calcined catalyst was reduced in a tube furnace at 773 K and 5% H2–N2 (by volume) for 5 h. Before exposure to air, the catalyst was passivated by purging with 1% O2–N2 by volume for 5 h at room temperature to obtain the corresponding NiZnO. x catalyst.
[0040] Add 0.5g xylose and 30mL deionized water to a 100mL high-pressure reactor, then add 0.15g catalyst. Replace the air in the reactor with nitrogen three to four times, then seal the reactor and stir at 800rpm. Heat to 255℃ under 8MPa H2 hydrogen pressure and maintain for 2h. After the reaction is completed and cooled to room temperature, separate the reaction mixture, take the supernatant, and prepare standard solutions of xylose, glycol, etc. Quantitative analysis is performed using liquid chromatography, and qualitative analysis is performed using gas chromatography-mass spectrometry. The results are listed in Table 1, serial numbers 34-39.
[0041] Examples 40-44
[0042] The corresponding magnetic catalysts were prepared according to the methods in Examples 1-10 for later use.
[0043] Add 0.5g xylose and 30mL deionized water to a 100mL high-pressure reactor, then add 0.15g catalyst. Replace the air in the reactor with nitrogen three to four times, then seal the reactor and stir at 800rpm. Heat to 245℃ under 6MPa H2 hydrogen pressure and maintain for 2h. After the reaction is complete, cool to room temperature, separate the reaction mixture, and dry under vacuum at 60℃ for 4h. Then, repeat the experiment five times. Use the supernatant to prepare standard solutions of xylose, glycol, etc., for quantitative analysis using liquid chromatography and qualitative analysis using gas chromatography-mass spectrometry. The results are listed in Table 1, numbers 40-44. The first to fifth cycles correspond to Examples 40-44, respectively.
[0044] The reusability of the catalyst was investigated. The reusability of the NiZn@TiO2 (3:8:4) catalyst was examined under the conditions of 245℃, 2h, and 6MPa H2. After each test, the catalyst was separated from the reaction mixture, dried under vacuum at 60℃ for 4h, and directly used for the next test. Over five consecutive uses, the catalytic activity of NiZn@TiO2 (3:8:4) continuously decreased, while the xylose conversion remained unchanged at 100%, and the diol yield decreased to some extent. After the fifth cycle, the diol yield decreased to 58.86%. The results show that after five cycles, the xylose conversion of the fresh catalyst remained unchanged at 100%, while the diol yield decreased slightly by about 5.3% (from 64.18% to 58.86%), indicating that the catalyst has excellent stability.
[0045] Table 1. Detection results of Examples 1–40
[0046]
[0047]
[0048] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.
Claims
1. A method for the catalytic conversion of xylose to diols, characterized in that: Xylose, catalyst, and deionized water were placed in a high-pressure reactor. The air in the reactor was replaced with nitrogen, and after thorough mixing, the reactor was sealed. The reaction was carried out in a closed system at 245°C and in the presence of hydrogen, with a stirring rate of 800 rpm, and then cooled to room temperature to obtain the diol. In the xylose-to-deionized water conversion process, the ratio of xylose to deionized water was 3.3 mmol:30 mL; the mass ratio of catalyst to xylose was 0.15 g:0.5 g; the hydrogen pressure in the reaction system was 8 MPa; and the diol included ethylene glycol, 1,2-propanediol, and 1,2-butanediol. The catalyst preparation method includes the following steps: 0.012 mol Ni(NO3)2·6H2O and 0.032 mol Zn(NO3)2·6H2O are dissolved in 20 mL of deionized water at room temperature, and then 0.016 mol of nano-TiO2 is added and sonicated for 30 min; subsequently, under magnetic stirring, a precipitant Na2CO3 solution is slowly added dropwise to adjust the pH of the mother liquor to 8, and then the mixture is continuously stirred and aged at 353 K for 3 h. The precipitate is then separated from the mother liquor by a vacuum filtration device, and the resulting filter cake is thoroughly washed with deionized water; the washed precipitate is then dried at 393 K for 12 h, cooled to room temperature, thoroughly ground in a mortar and passed through a 100-mesh sieve, and then calcined in air at 673 K for 4 h; finally, the calcined catalyst is reduced in a tube furnace at 773 K and 5% H2–N2 for 5 h; and before exposure to air, the catalyst is purged with 1% O2–N2 at room temperature for 5 h. h is passivated; wherein, Ni(NO3)2·6H2O, Zn(NO3)2·6H2O and nano TiO2 are in a molar ratio of 3:8:4 based on Ni, Zn and TiO2.