Process for the hydrogenation of furfural and its derivatives to polyols

Abstract

The present application belongs to the technical field of biomass catalytic conversion, and particularly relates to a method for preparing polyols by hydrogenation of furfural and its derivatives. The method comprises the following steps: taking furfural and its derivatives as raw materials, hydrogen as hydrogen source, and simultaneously adding a catalyst La2CuO4 / Cu to perform ring-opening reaction to obtain polyols. The catalyst La2CuO4 / Cu has excellent catalytic activity in the reaction of hydrogenation conversion of furfural and its derivatives into polyols, has high activity and selectivity for the rupture of C-O bonds of reactants, improves the yield of polyols, and has mild reaction conditions, realizes recovery and long-time use without deactivation of the catalyst, and reduces the utilization cost.

Description

Technical Field

[0001] This invention belongs to the field of biomass catalytic conversion technology, specifically relating to a method for preparing polyols by hydrogenation of furanaldehyde and its derivatives. Background Technology

[0002] Furanaldehyde and its derivatives are currently mostly obtained from agricultural and forestry waste rich in hemicellulose through processes such as acid catalysis and dehydration. Since furanaldehyde and its derivatives have unsaturated C=C and C=O bonds, they can be further synthesized into high-value-added fine chemical polyols through catalytic hydrogenolysis. Polyols (such as 1,2-pentanediol) can not only be used in the production of moisturizers, crop protectants and pesticides in cosmetics and pharmaceuticals, but also in the synthesis of polyester fibers, antifreeze and fine chemicals, etc., realizing the conversion of renewable biomass raw materials into chemicals and fuels, which can alleviate the current increasingly serious environmental pollution and resource scarcity problems.

[0003] Currently, while noble metal catalysts, especially Pt, exhibit excellent catalytic performance in the hydrogenolysis of furan aldehydes and their derivatives to polyols, their high cost limits their large-scale application. Addressing this bottleneck, non-noble metal catalysts, primarily composed of abundant transition metals such as copper and nickel, have become a research focus in the hydrogenolysis of furan aldehydes and their derivatives to polyols. Current research aims to systematically improve their intrinsic activity and selectivity through strategies such as support regulation, alloying, and interface engineering. However, challenges remain, including demanding reaction conditions, poor selectivity for target products, and limited catalyst reusability. Summary of the Invention

[0004] To address the shortcomings of existing methods, this invention provides a method for preparing polyols by hydrogenation of furanaldehyde and its derivatives.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing polyols by hydrogenation of furanaldehyde and its derivatives includes the following steps: Using furanaldehyde and its derivatives as raw materials, hydrogen as the hydrogen source, and the catalyst La2CuO4 / Cu, a ring-opening reaction is carried out to obtain polyols.

[0006] Preferably, the furfural and its derivatives are at least one selected from furfural, furfuryl alcohol, 5-hydroxymethylfurfural, 5-methylfurfural and 5-methylfurfural.

[0007] Preferably, the mass ratio of furanaldehyde and its derivatives to the catalyst La2CuO4 / Cu is 50-150 mg: 10-100 mg; the ring-opening reaction temperature is 130-170℃, the reaction time is 4-12 h, and the hydrogen pressure is 3-6 MPa.

[0008] Preferably, the ring-opening reaction process further includes the addition of an organic solvent, which is at least one of methanol, ethanol, isopropanol, tetrahydrofuran, and 1,4-dioxane.

[0009] Preferably, the catalyst La2CuO4 / Cu is prepared by dissolving copper salt and lanthanum salt in deionized water, stirring until completely dissolved, and then adding it dropwise to a mixed alkaline solution. The process is then carried out in sequence, including aging, filtration, drying, calcination, and reduction, to obtain the catalyst.

[0010] Preferably, the total molar amount of the lanthanum salt and copper salt, the volume of deionized water, and the volume ratio of the mixed alkaline solution are 0.01 mol: 20-40 mL: 20-40 mL, and the molar percentage of the lanthanum salt in the total salt is 2%-40%.

[0011] Preferably, the copper salt is at least one of copper nitrate trihydrate, anhydrous copper chloride, and copper acetate; the lanthanum salt is at least one of lanthanum nitrate hexahydrate, lanthanum carbonate, and lanthanum chloride; and the concentration of sodium hydroxide in the mixed alkaline solution is 0.8-2 mol / L, and the concentration of sodium carbonate is 0.1-0.5 mol / L.

[0012] Preferably, the aging temperature is 30-120℃ and the aging time is 2-12h.

[0013] Preferably, the calcination temperature is 300-700℃ and the calcination time is 2-6h.

[0014] Preferably, the reduction conditions are: in-situ reduction at 130-150°C for 1-3 hours in a reactor or reduction at 280-320°C for 1-3 hours in a hydrogen tubular furnace.

[0015] The positive and beneficial effects of this invention are as follows: 1. The catalyst of this invention, La2CuO4 / Cu, is a reverse copper-lanthanide metal catalyst. La and Cu interact to form La2CuO4 composite oxide. Cu and La species have good composite and dispersion states. The La-O sites and related defect structures in La2CuO4 are conducive to the adsorption and activation of substrate molecules. The interaction with Cu sites makes the catalyst more active and stable, promoting the hydrogenation ring-opening conversion of furan aldehyde and its derivatives. Moreover, it uses inexpensive transition metals as catalyst raw materials, and the preparation method is simple and low-cost, which is conducive to large-scale production.

[0016] 2. The catalyst La2CuO4 / Cu of this invention exhibits excellent catalytic activity in the hydrogenation conversion of furan aldehyde and its derivatives into polyols. It has high activity and selectivity in breaking the CO bonds of the reactants, thereby improving the yield of polyols. Moreover, the reaction conditions are mild, enabling catalyst recovery and long-term use without deactivation, thus reducing its utilization cost. Attached Figure Description

[0017] Figure 1 Here is a SEM image of the La2CuO4 / Cu catalyst of this invention; Figure 1 In the middle: (a) 90La / Cu, (b) 40La / Cu, (c) 20La / Cu, (d) 10La / Cu, (e) 2La / Cu; (fi) is the EDS spectrum of Cu, La and O in the 10La / Cu catalyst.

[0018] Figure 2 This is a TEM image of the La2CuO4 / Cu catalyst of the present invention; Figure 2 In the middle: (a) 20La / Cu, (b) 10La / Cu, (c) 2La / Cu; (dg) is the EDS spectrum of Cu, La and O in the 10La / Cu catalyst.

[0019] Figure 3 This is the EPR diagram of the La2CuO4 / Cu catalyst of the present invention.

[0020] Figure 4 This is a diagram showing the cycling effect of the La2CuO4 / Cu catalyst of this invention; Figure 4 In this context, FFA stands for furfuryl alcohol; THFA stands for tetrahydrofurfuryl alcohol; 1,2-PeD stands for 1,2-pentanediol; 1,5-PeD stands for 1,5-pentanediol; 1-PeOH stands for 1-pentanol; and 2-MF stands for 2-methylfuran. Detailed Implementation

[0021] The present invention will be further described below with reference to some specific embodiments.

[0022] The preparation method of the catalyst La2CuO4 / Cu of the present invention includes the following steps: S1, copper nitrate trihydrate and lanthanum nitrate hexahydrate are dissolved in 60 mL of deionized water as metal salt solution A. The total molar amount of copper salt and lanthanum salt is 0.02 mol, and the molar percentage of lanthanum nitrate hexahydrate in the total salt is 2%-90%. S2, 2.4g NaOH and 1.908g Na2CO3 are dissolved in 60mL of deionized water to form mixed alkaline solution B. The concentration of sodium hydroxide in the mixed alkaline solution is 1mol / L and the concentration of sodium carbonate is 0.3mol / L. S3. Slowly add metal salt solution A to mixed alkaline solution B and age at 70℃ for 4 hours; S4. The sample obtained in step S3 is filtered multiple times. The precursor is dried in an oven at 80°C for 12 hours, calcined in a muffle furnace at 500°C for 4 hours, and finally calcined in a hydrogen tube furnace at 300°C. oC is reduced for 2 hours to obtain the product.

[0023] SEM images of the La2CuO4 / Cu catalyst of this invention are shown below. Figure 1 Samples with different La contents exhibited significant morphological differences. At high La proportions, the material was dominated by amorphous aggregates with severe particle accumulation. As the La content decreased, plate-like and rod-like structures gradually appeared, interspersed with fine particles. The 10La / Cu catalyst (where 10 indicates a 10% molar percentage of lanthanum salt in the total salt, similar for other catalysts) showed a more pronounced nanorod-like interwoven structure. The rod-like units interweave to form a loose three-dimensional network, while a certain number of irregular particles adhere to the surface, indicating a good composite and dispersion state between Cu and La species. When the La content was too low, the rod-like structure further coarsens and stacked, with more pronounced local particle aggregation. Figure 1 ae). EDS map ( Figure 1 The results showed that Cu, La and O elements were relatively uniformly distributed in the overall particles of the 10La / Cu catalyst, indicating that Cu and La species can coexist well in the catalyst structure.

[0024] TEM image of the catalyst La2CuO4 / Cu of this invention is shown below. Figure 2 Transmission electron microscopy (TEM) analysis was performed on La₂CuO₄ / Cu catalysts with ratios of 20La / Cu, 10La / Cu, and 2La / Cu. The images confirmed that La primarily exists in the forms of La₂O₂CO₅ and La₂CuO₄, with lattice spacings of 0.302 nm and 0.287 nm corresponding to the (130) plane of La₂O₂CO₅ and the (113) plane of La₂CuO₄. Figure 2 ac). EDS map ( Figure 2 The dg results showed that the La species in the 10La / Cu catalyst mainly existed in the form of La2CuO4, and the TEM-EDS pattern further confirmed the uniform distribution of Cu and La.

[0025] The EPR test results of the catalyst La2CuO4 / Cu of this invention are shown below. Figure 3 The spectral results showed that all samples exhibited typical oxygen vacancy (g=2.003) characteristic signals, and the signal intensity showed a clear volcano-like trend with the change of La ratio. Among them, the 10La / Cu catalyst had the highest oxygen vacancy signal intensity, indicating that the sample surface contained the most abundant oxygen vacancy defect sites, which is related to the La2CuO4 phase and the Cu-O-La interface induced by it, thereby better enhancing the adsorption and activation of reactants and improving the catalytic reaction performance.

[0026] Example 1

[0027] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: In a 50 mL stainless steel high-pressure reactor, 5 mL of isopropanol, 100 mg of furfuryl alcohol, 50 mg of catalyst with different lanthanum / copper salt molar ratios, and 100 mg of tridecane internal standard were added. After stirring, the reactor was sealed and purged five times with 1 MPa hydrogen gas. Then, 6 MPa hydrogen gas was introduced into the reactor, and the reaction was carried out at 140 °C for 9 h. After the reaction was completed, the reaction solution was filtered through a 0.45 μm filter to remove the solid catalyst. The conversion rate of furfuryl alcohol and the selectivity of each product were calculated using the standard curve method with gas chromatography-mass spectrometry and gas chromatography. The reaction results are shown in Table 1.

[0028] Table 1 Catalytic effects of catalysts with different lanthanum / copper salt ratios As shown in Table 1, with the increase of copper content, the conversion of reactants first increases and then decreases. For the selectivity of the target product 1,2-pentanediol, it shows a trend of first increasing and then decreasing. When the molar proportion of lanthanum salt in the total salt is 10% (10La / Cu), furfuryl alcohol achieves a conversion of 90.1%, and the selectivity of 1,2-pentanediol is 72.5%.

[0029] Example 2

[0030] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: In a 50 mL stainless steel high-pressure reactor, 5 mL of different organic solvents, 100 mg of furfuryl alcohol, 50 mg of catalyst, and 100 mg of tridecane internal standard were added respectively. After stirring, the reactor was sealed and purged with 1 MPa hydrogen five times. Then, 6 MPa hydrogen was introduced into the reactor, and the reaction was carried out at 140 °C for 9 h. After the reaction was completed, the reaction solution was filtered through a 0.45 μm filter to remove the solid catalyst. The conversion rate of furfuryl alcohol and the selectivity of each product were calculated by standard curve method using gas chromatography-mass spectrometry and gas chromatography. The reaction results are shown in Table 2.

[0031] Table 2 Catalytic effect under different solvents As shown in Table 2, the solvent has a significant impact on the reverse 10La / Cu catalytic furfuryl alcohol reaction. When the solvent is an alcohol, the main product 1,2-pentanediol is produced in greater quantities. The reaction is most effective when the solvent is isopropanol, with a furfuryl alcohol conversion rate of 90.1% and a selectivity of 72.5% for the target product 1,2-pentanediol.

[0032] Example 3

[0033] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: In a 50 mL stainless steel high-pressure reactor, 5 mL of isopropanol, 100 mg of furfuryl alcohol, 50 mg of catalyst, and 100 mg of tridecane internal standard were added. After stirring, the reactor was sealed and purged five times with 1 MPa hydrogen gas. Then, 6 MPa of hydrogen gas was introduced into the reactor. The reaction was carried out at different temperatures of 130-170 °C for 9 h. After the reaction was completed, the reaction solution was filtered through a 0.45 μm filter to remove the solid catalyst. The conversion rate of furfuryl alcohol and the selectivity of each product were calculated using the standard curve method with gas chromatography-mass spectrometry and gas chromatography. The reaction results are shown in Table 3.

[0034] Table 3 Catalytic effect at different reaction temperatures As shown in Table 3, the conversion rate of reactants generally shows a gradual increasing trend with the increase of reaction temperature. The selectivity of the target product 1,2-pentanediol first increases and then decreases with the increase of temperature. The selectivity of 1,2-pentanediol reaches the maximum of 72.5% at 140℃. Further increases in temperature will lead to an increase in the selectivity of 1,5-pentanediol and other products.

[0035] Example 4

[0036] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: In a 50 mL stainless steel high-pressure reactor, add 5 mL isopropanol, 100 mg furfuryl alcohol, 50 mg catalyst, and 100 mg tridecane internal standard. After stirring, seal the reactor and purge it five times with 1 MPa hydrogen. Then, introduce 1-6 MPa hydrogen into the reactor and react at 140 °C for 9 h. After the reaction is complete, filter the reaction solution through a 0.45 μm filter to remove the solid catalyst. Calculate the conversion rate of furfuryl alcohol and the selectivity of each product using the standard curve method with gas chromatography-mass spectrometry and gas chromatography. The reaction results are shown in Table 4.

[0037] Table 4 Catalytic effect under different reaction pressures As shown in Table 4, the conversion rate of the reactants generally shows a gradual increasing trend with the increase of reaction pressure. The selectivity of the target product 1,2-pentanediol also generally increases slightly with the increase of pressure. The selectivity of 1,2-pentanediol reaches the maximum of 72.5% at 6 MPa. Meanwhile, for safety reasons, the hydrogen pressure of this invention is selected as 3-6 MPa.

[0038] Example 5

[0039] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: In a 50 mL stainless steel high-pressure reactor, add 5 mL isopropanol, 100 mg furfuryl alcohol, 50 mg catalyst, and 100 mg tridecane internal standard. After stirring, seal the reactor and purge it five times with 1 MPa hydrogen gas. Then, introduce 6 MPa hydrogen gas into the reactor and react at 140 °C for 1-12 h. After the reaction is complete, filter the reaction solution through a 0.45 μm filter to remove the solid catalyst. Calculate the conversion rate of furfuryl alcohol and the selectivity of each product using the standard curve method with gas chromatography-mass spectrometry and gas chromatography. The reaction results are shown in Table 5.

[0040] Table 5 Catalytic effect at different reaction times As shown in Table 5, the conversion rate of the reactants gradually increases with the increase of reaction time. When the reaction time is extended to 12 h, the substrate is completely converted. At this time, the selectivity for the target product 1,2-pentanediol is 72.8%.

[0041] Example 6

[0042] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: Different concentrations of furfuryl alcohol were added to a 50 mL stainless steel high-pressure reactor. The total amount of solvent and substrate furfuryl alcohol was 2 g. No internal standard was added, and the furfuryl alcohol concentration ranged from 5% to 100%. A catalyst was added, with the catalyst mass being one-tenth of the furfuryl alcohol mass. After stirring, the reactor was sealed, and the reactor was purged five times with 1 MPa hydrogen gas. The reactor was then charged with 6 MPa hydrogen gas and reacted at 140 °C for 9 h. After the reaction was completed, the reaction solution was filtered through a 0.45 μm filter to remove the solid catalyst. The conversion rate of furfuryl alcohol and the selectivity of each product were calculated using the peak area method with gas chromatography-mass spectrometry and gas chromatography. The reaction results are shown in Table 6.

[0043] Table 6 Catalytic effect at different concentrations of furfuryl alcohol As shown in Table 6, the conversion rate of furfuryl alcohol gradually increases with increasing substrate concentration. The selectivity for the target product, 1,2-pentanediol, remains relatively stable at around 70%, while the selectivity for other non-target products (1-pentanol, 2-methylfuran, tetrahydrofurfuryl alcohol) decreases accordingly. This indicates that the reactivity of the target product in this catalytic system is largely unaffected by substrate concentration, demonstrating promising prospects for industrial application.

[0044] Example 7

[0045] A method for preparing 1,2-pentanediol by hydrogenation of furanaldehyde and its derivatives includes the following steps: In a 50 mL stainless steel high-pressure reactor, add 5 mL isopropanol, 100 mg furfuryl alcohol, 50 mg catalyst, and 100 mg tridecane internal standard. After stirring, seal the reactor and purge it five times with 1 MPa hydrogen gas. Then, introduce 6 MPa hydrogen gas into the reactor and react at 140 °C for 9 hours. Centrifuge the catalyst and solution after the reaction, and take the supernatant for product analysis. Add isopropanol to the remaining mixture of reaction solution and catalyst, wash and centrifuge three times, and then place it in a vacuum oven at 60 °C. o The catalyst was dried at C for 12 hours to obtain the recovered catalyst. The above steps were then repeated five times. Each time, the conversion rate of furfuryl alcohol and the selectivity of each product were calculated using gas chromatography-mass spectrometry and the standard curve method. The reaction results are shown in [Figure number missing]. Figure 4 .

[0046] Depend on Figure 4 It is evident that the catalyst of this invention maintains high activity after five cycles of use, and there is no significant decrease in the conversion rate of furfuryl alcohol and the selectivity for the target product 1,2-pentanediol, proving that it has good reusability. This invention achieves catalyst recovery and long-term use without deactivation, reducing its utilization cost.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing polyols by hydrogenation of furanaldehyde and its derivatives, characterized in that, Includes the following steps: Using furanaldehyde and its derivatives as raw materials, hydrogen as the hydrogen source, and the catalyst La2CuO4 / Cu, a ring-opening reaction is carried out to obtain polyols.

2. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 1, characterized in that, The furfural and its derivatives are at least one of furfural, furfuryl alcohol, 5-hydroxymethylfurfural, 5-methylfurfural and 5-methylfurfural.

3. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 1, characterized in that, The mass ratio of furanaldehyde and its derivatives to the catalyst La2CuO4 / Cu is 50-150 mg: 10-100 mg; the ring-opening reaction temperature is 130-170℃, the reaction time is 4-12 h, and the hydrogen pressure is 3-6 MPa.

4. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 1, characterized in that, The ring-opening reaction process also involves the addition of an organic solvent, which is at least one of methanol, ethanol, isopropanol, tetrahydrofuran, and 1,4-dioxane.

5. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 1, characterized in that, The catalyst La2CuO4 / Cu is prepared by dissolving copper salt and lanthanum salt in deionized water, stirring until completely dissolved, and then adding it dropwise to a mixed alkaline solution. The process is then carried out in sequence, including aging, filtration, drying, calcination, and reduction, to obtain the catalyst.

6. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 5, characterized in that, The total molar amount of lanthanum salt and copper salt, the volume of deionized water, and the volume ratio of the mixed alkaline solution are 0.01 mol: 20-40 mL: 20-40 mL, and the molar percentage of lanthanum salt in the total salt is 2%-40%.

7. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 5, characterized in that, The copper salt is at least one of copper nitrate trihydrate, anhydrous copper chloride, and copper acetate; the lanthanum salt is at least one of lanthanum nitrate hexahydrate, lanthanum carbonate, and lanthanum chloride; the concentration of sodium hydroxide in the mixed alkaline solution is 0.8-2 mol / L, and the concentration of sodium carbonate is 0.1-0.5 mol / L.

8. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 5, characterized in that, The aging temperature is 30-120℃, and the aging time is 2-12h.

9. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 5, characterized in that, The calcination temperature is 300-700℃, and the calcination time is 2-6h.

10. The method for preparing polyols by hydrogenation of furanaldehyde and its derivatives according to claim 5, characterized in that, The reduction conditions are: in-situ reduction at 130-150℃ for 1-3 hours in a reactor or reduction at 280-320℃ for 1-3 hours in a hydrogen tubular furnace.

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