Method for preparing bio-based furan chemical from Juncao

Abstract

The invention provides a method for preparing a bio-based furan chemical from Juncao, which comprises the following specific steps of: firstly, carrying out hydrolysis and dehydration reaction on a Juncao hemicellulose component by using an acid catalyst to obtain furfural; then, furfural reacts in a hydrogen atmosphere under a high-temperature condition, and is converted into various bio-based furan chemicals through different metal catalysts; solid residues obtained after furfural is prepared from the recycled Juncao are Juncao cellulose and can be used for preparing pulp, plates and high-added-value chemicals, and the comprehensive added value of the Juncao is increased. The method has the advantages that the full-component utilization rate of the biomass is high, the bio-based furan chemicals can be derived from the biomass Juncao, and the method has both economic benefits and social benefits and has industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of bio-based furans, and specifically provides a method for preparing bio-based furan chemicals from Juncao (a kind of grass). Background Art

[0002] Juncao is a perennial herbaceous plant with high photosynthetic efficiency, large biomass, developed root system, high yield, strong biological stress resistance, cold tolerance, drought tolerance, waterlogging tolerance, salt-alkali tolerance, and fast forestation speed, with a yield of up to 25 tons per mu. Juncao has a high content of total cellulose and is easy to extract, and is one of the potential biomass raw materials for producing bio-based chemicals. At present, Juncao is mainly used for the cultivation of edible fungi, animal feed, sand fixation, etc., and there are few reports in the field of chemical production. Furan-based bio-based materials have been particularly popular recently. Furan is widely used in organic synthesis and pharmaceutical production to manufacture various chemical raw materials and drugs, such as pyrrole, thiophene, tetrahydrofuran, and benzofuran. Bio-based tetrahydrofuran is used to produce bio-based spandex, and the carbon emissions throughout the process can be reduced by more than 70%. Producing furan chemicals from biomass Juncao resources via furfural intermediates has broad industrial application prospects.

[0003] The present application aims to provide a method for preparing bio-based furan chemicals from Juncao. The hemicellulose component of Juncao is used to prepare furan, tetrahydrofuran, 2-methylfuran and other furan chemicals via furfural intermediates. The recovered solid residue, Juncao cellulose, can be used to prepare pulp, boards, and high-value-added chemicals, improving the comprehensive added value of Juncao, expanding the industrial chain of Juncao, and having cost advantages and environmental protection advantages. Summary of the Invention

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing bio-based furan chemicals from Juncao, which is carried out in three steps: (a) The hemicellulose component of Juncao is converted into furfural through dehydration and hydrolysis reactions. The conversion of the hemicellulose component of Juncao to furfural preferably occurs in the catalyst defined below. Preferably, it is sulfuric acid, and the furfural yield provided by it is greater than 55%; (b) At least a part of furfural is catalytically converted into bio-based furan chemicals, and furfural undergoes a hydrogenation reaction on the metal catalyst defined below to be converted into bio-based furan chemicals; (b) After producing furfural from Juncao, the solid residue is recovered as Juncao cellulose, and the Juncao cellulose can obtain natural-colored pulp of Juncao through alkali cooking, with a yield exceeding 30%.

[0006] Step (a) includes the hydrolysis and dehydration reactions of Juncao by contacting it with an acidic catalyst and water; the acidic catalyst is a group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, citric acid, and their components; the mass ratio of the acidic catalyst to Juncao is 1% - 10%.

[0007] In step (b), at least a portion of the furfural is hydrogenated into a biomass-based furan chemical by contacting the furfural with a catalyst, wherein the catalyst comprises a metal selected from the group consisting of Pd, Pt, Ru, Rh, Fe, Ni, Cu, and combinations thereof. The biomass-based furan chemical comprises one or more of furan, tetrahydrofuran, 2-methylfuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol.

[0008] Step (b) occurs at a temperature of 100-400°C and a pressure of 0.1 to 6.0 MPa.

[0009] In step (c), the hemicellulose content of the Juncao cellulose is less than 2%, and the cellulose content is >50%; the Juncao cellulose can be used to prepare pulp, boards, and high-value chemicals.

[0010] This invention first uses an acidic catalyst to hydrolyze and dehydrate the hemicellulose component of Juncao grass to obtain furfural. Then, furfural is reacted under hydrogen atmosphere and high temperature conditions, and different metal catalysts are used to convert furfural into different kinds of high-value-added bio-based furan chemicals. The solid residue after furfural production from Juncao grass is recycled as Juncao cellulose, which can be used to prepare pulp, boards, and high-value-added chemicals, thereby increasing the overall added value of Juncao grass.

[0011] Compared with existing technologies, this application has at least the following advantages: using biomass-based fungal grass as raw material avoids the difficulties in reusing cellulose and lignin from corn cobs; the recovered solid residue can be used to prepare high-value-added chemicals, pulp, and boards, offering both cost and environmental advantages. The method also boasts high utilization of all biomass components, and bio-based furan chemicals can be derived from biomass-based fungal grass, combining economic and social benefits and showing promise for industrial application. Detailed Implementation

[0012] The invention can be better understood through the following examples. However, the description is for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0013] All raw materials used in this invention are not subject to any particular purity restrictions, and all reagents used in the following examples are commercially available. Step (a) Qualitative and quantitative analysis of furfural: High-performance liquid chromatography (HPLC) was performed using an Agilent 1260, with an 87-H ion-exchange column at 65°C and a parallax refractive index detector at 50°C; mobile phase: 5 Mm H₂SO₄, flow rate: 0.6 ml / min, injection volume: 25 μL. Step (b) Qualitative analysis of the reactants and liquid products furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol was conducted using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument. Confirmation was achieved through mass spectrometry library searches combined with standard retention time comparisons. Quantitative analysis: The products were quantitatively analyzed using an Agilent gas chromatograph (HP-5 capillary column, FID flame ionization detector) with an internal standard method. The internal standard was n-heptanol. Construction of the internal standard working curve: Accurately weigh 0.6 g of furfural, 2.5 g of furan, 0.1 g of 2-methylfuran, 0.1 g of tetrahydrofuran, 0.1 g of 2-methyltetrahydrofuran, 0.2 g of furfuryl alcohol, and 0.1 g of tetrahydrofurfuryl alcohol standards, mix them, and dilute with ethanol to a final volume of 5.0 g to obtain the standard stock solution. Then, transfer 0.02 g, 0.05 g, 0.15 g, 0.25 g, 0.45 g, 0.65 g, 0.85 g, and 1.0 g of the stock solution, respectively, and dissolve 0.05 g of n-heptanol. Add 1.5 mL of ethanol to make up the volume, and then perform gas chromatography analysis. Record the values ​​of the analytes (furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, tetrahydrofurfuryl alcohol) and the standard n-heptanol. The peak area ratio (Ai / As, where Ai represents the peak area of ​​the analyte and As represents the peak area of ​​the standard) was used as the abscissa. The mass ratios (mi / ms) of furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, tetrahydrofurfuryl alcohol, and n-heptanol in each solution were calculated as the ordinate. A standard working curve of raw materials and products was plotted, and the amount of products was calculated. Quantitative analysis of reaction gaseous products: A Pannolog gas chromatograph connected online to a fixed-bed reactor (with a TCD / FID flame ionization detector) was used to quantitatively analyze CO, C2, C3, C4, furan, 2-methylfuran, tetrahydrofuran, and 2-methyltetrahydrofuran products using the external standard method, and the amount of products was calculated.

[0014] Example A (Standard furfural decarbonylation to furan)

[0015] Step (a): 1000g of Juncao "Oasis No. 1" (produced in Fengqiu, Henan) was mixed evenly with 500g of sulfuric acid solution with a mass concentration of 2.8wt% and placed in a hydrolysis kettle. 180℃ water vapor was continuously passed into the hydrolysis kettle for 4 hours. The condensed steam was collected and purified by distillation to obtain furfural with a yield of 65%.

[0016] Step (b): The catalytic conversion of furfural to furan was carried out in a fixed-bed reactor at atmospheric pressure and a temperature of 260-300℃. The mass hourly space velocity (MSV) of the furfural feed was 3.48 h⁻¹, the molar ratio of hydrogen to furfural was 2.46, and the run time was 8 hours. The evaluation results are shown in Table 1. The metal mass loading in the catalyst (purchased from Shaanxi Ruike) ranged from 0.25% to 1.0%.

[0017] Step (c): After the furfural is produced from Juncao (step (a)), the solid residue is recovered and mixed with 5wt% NaOH solution at a solid-liquid ratio of 1:5 (g / mL). The mixture is then cooked at 160℃ for 2 hours. After cooking, Juncao colored pulp and black liquor are separated using a pulp bag. The yield of Juncao colored pulp is 31%, and the mass content of cellulose A is 82%.

[0018]

[0019] Example B (Hydrogenation of furfural to tetrahydrofurfural)

[0020] Step (a): 1000g of Juncao "Oasis No. 1" (produced in Fengqiu, Henan) and 500g of 2.8wt% sulfuric acid solution were sprayed evenly into a hydrolysis reactor. 180℃ steam was continuously passed through the reactor for 4 hours. The condensed steam was collected and purified by distillation to obtain furfural with a yield of 65%. Step (b): The catalytic conversion of furfural to tetrahydrofurfuryl alcohol was carried out in a fixed-bed reactor. The hydrogen pressure was 2.0MPa, the reaction temperature was 120℃, the hydrogen-aldehyde molar ratio was 20:1, the liquid hourly space velocity (LHSV) of furfural was 0.2h⁻¹, and the running time was 8 hours. The evaluation results are shown in Table 2. The catalyst preparation method refers to Chinese Patent CN2022114376414, with metal content ranging from 10% to 30%. Step (c): After furfural is produced from Juncao, the recovered solid residue is mixed with 5wt% NaOH solution at a solid-liquid ratio of 1:5 (g / mL) and cooked at 160℃ for 2 hours. After cooking, Juncao colored pulp and black liquor are separated using a pulp bag. The yield of Juncao colored pulp is 31%, and the content of methyl cellulose is 82%.

[0021]

[0022]

[0023] Example C (Furfural hydrogenation to furfuryl alcohol)

[0024] Step (a): 1000g of Juncao "Oasis No. 1" (produced in Fengqiu, Henan) and 500g of 2.8wt% sulfuric acid solution were sprayed evenly into a hydrolysis reactor. 180℃ steam was continuously passed through the reactor for 4 hours. The condensed steam was collected and purified by distillation to obtain furfural with a yield of 65%. Step (b): The catalytic conversion of furfural to furfuryl alcohol was carried out in a fixed-bed reactor at a pressure of 0.1-5MPa, a temperature of 120-200℃, a mass hourly space velocity (MSV) of 1.6h⁻¹ for the furfural feed, a hydrogen-to-furfural molar ratio of 10, and a running time of 8 hours. The evaluation results are shown in Table 3. The catalyst preparation process is referenced (Catal. Sci. Technol., 2021021, 11, 297–311; Journal of Fuel Chemistry, 2024, 52, 1045-1054). Step (c): After furfural is produced from Juncao, the recovered solid residue is mixed with 5wt% NaOH solution at a solid-liquid ratio of 1:5 (g / mL) and cooked at 160℃ for 2 hours. After cooking, Juncao colored pulp and black liquor are separated using a pulp bag. The yield of Juncao colored pulp is 31%, and the content of methyl cellulose is 82%.

[0025]

[0026] Example D (Hydrogenation of furfural to 2-methylfuran)

[0027] Step (a): 1000g of Juncao "Oasis No. 1" (produced in Fengqiu, Henan) and 500g of 2.8wt% sulfuric acid solution were sprayed evenly into a hydrolysis reactor. 180℃ steam was continuously passed through the reactor for 4 hours. The condensed steam was collected and purified by distillation to obtain furfural with a yield of 65%. Step (b): The catalytic conversion of furfural to 2-methylfuran was carried out in a fixed-bed reactor at atmospheric pressure, a reaction temperature of 160-250℃, a furfural feed mass hourly space velocity of 0.5 h⁻¹, a hydrogen to furfural molar ratio of 8.0, and a running time of 8 hours. The evaluation results are shown in Table 4. Raney copper was purchased from Dalian General Chemical. The preparation process of other catalysts is as follows (Journal of Molecular Catalysis A: Chemical, 2015, 398, 140-148, Journal of Fuel Chemistry, 2024, 52, 1045-1054): Step (c) is as follows: After furfural is produced from Juncao, the recovered solid residue is mixed with 5wt% NaOH solution at a solid-liquid ratio of 1:5 (g / mL) and cooked at 160℃ for 2 hours. After cooking, Juncao colored pulp and black liquor are separated by a pulp bag. The yield of Juncao colored pulp is 31%, and the content of methyl cellulose is 82%.

[0028]

[0029]

[0030] Example E (Hydrogenation of furfural to tetrahydrofuran)

[0031] Step (a): 1000g of Juncao "Oasis No. 1" (produced in Fengqiu, Henan) and 500g of 2.8wt% sulfuric acid solution were sprayed evenly into a hydrolysis reactor. 180℃ steam was continuously passed through the hydrolysis reactor for 4 hours. The condensed steam was collected and purified by distillation to obtain furfural with a yield of 65%. Step (b): The reaction of furfural to tetrahydrofuran via catalytic conversion was carried out in two series-connected fixed-bed reactors. In the first stage, furfural reacted at 300℃ and atmospheric pressure with a mass hourly space velocity (MHSV) of 3.48 h⁻¹, and the molar ratio of hydrogen to furfural was 2.46. The product from the first stage entered the second stage reactor with a MHSV of 1.0 h⁻¹, a reaction pressure of 3.0 MPa, a reaction temperature of 140℃, and a running time of 8 hours. The evaluation results are shown in Table 5. The catalyst was purchased from Shaanxi Ruike and Dalian General Chemical. Step (c): After furfural was produced from Juncao, the solid residue was recovered and mixed with 5wt% NaOH solution at a solid-liquid ratio of 1:5 (g / mL). The mixture was then cooked at 160℃ for 2 hours. After cooking, Juncao colored pulp and black liquor were separated using a pulp bag. The yield of Juncao colored pulp was 31%, and the content of methyl cellulose was 82%.

[0032]

Claims

1. A method for producing bio-based furan chemicals from Juncao grass, the specific process including: (a) The hemicellulose component of Juncao grass is converted into furfural; (b) To catalytically convert at least some or all of furfural into bio-based furan chemicals.

2. The method according to claim 1, wherein, Step (a) involves the hydrolysis and dehydration of the Juncao grass through contact with an acidic catalyst and water.

3. The method according to claim 2, wherein, The acidic catalyst is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid.

4. The method according to claim 2 or 3, wherein, The mass ratio of the acidic catalyst to the Juncao grass is 0.1%-5%, preferably 0.5%-2%; The solid-liquid ratio of Juncao to the aqueous solution is 10:1 to 1:10, preferably 5:1; the reaction temperature is 150-200 degrees Celsius, preferably 160-180 degrees Celsius; and the reaction time is 1 hour to 8 hours, preferably 2-4 hours.

5. The method according to claim 1, wherein, In step (b), in a hydrogen atmosphere, at least some or all of the furfural is hydrogenated into biomass-based furan chemicals by contacting the furfural with a catalyst. The active components of the catalyst include one or more selected from Pd, Pt, Ru, Rh, Fe, Ni, and Cu.

6. The method according to claim 5, wherein the active component of the catalyst accounts for 0.01% to 50% of the mass content of the catalyst, preferably 0.2% to 30%.

7. The method according to claim 1 or 5, wherein the biomass-based furan chemical comprises one or more of furan, tetrahydrofuran, 2-methylfuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol.

8. The method according to claim 1 or 5, wherein, Step (b) occurs at a temperature of 100-400°C and a pressure of 0.1 to 6.0 MPa.

9. The method according to claim 1, characterized in that, It also includes step (c), in which the solid residue after furfural production from Juncao is recovered as Juncao cellulose, wherein the hemicellulose content is less than 2% and the cellulose content is >50%, and the Juncao cellulose can be used to prepare pulp, boards or high-value chemicals.

10. The method according to claim 9, characterized in that, The process of preparing Juncao pulp by alkali boiling Juncao cellulose is as follows: the solid residue is mixed with 2wt%-10wt% NaOH solution at a solid-liquid ratio of 1:2-1:10 (g / mL) and boiled at 100-200℃ for 0.5-6 hours. The solid and liquid are separated to obtain Juncao colored pulp and black liquor.

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