Application of bimetal organic framework material in production of high-added-value organic acid through hydrothermal catalysis of synergistic conversion of biomass and carbon dioxide

Abstract

The invention relates to application of a bimetal organic framework material in production of high-added-value organic acid through hydrothermal catalysis of synergistic conversion of biomass and carbon dioxide. Transition metal Cu is introduced through an element substitution method to synthesize the bimetal organic framework material MIL-53 (Fe, Cu), and the bimetal organic framework material MIL-53 (Fe, Cu) is applied to hydrothermal catalytic biomass and CO2 synergistic conversion to produce high-added-value organic acid. On one hand, the bimetal organic framework material MIL-53 (Fe, Cu) accelerates hydrolysis of biomass derived carbohydrate-cellulose into glucose, and then promotes isomerization of glucose into fructose, reverse aldol condensation of fructose to glyceraldehyde and glyceraldehyde bond breaking to produce formaldehyde and glyceraldehyde in the cascade reaction process; further carrying out oxidation reduction with a CO2 solid source, namely NaHCO3 to produce high-added-value organic acid; on the other hand, NaHCO3 is reduced into formic acid through hydrogen production by splitting water from glucose; and finally, synergistic catalytic conversion of biomass and CO2 to high-added-value organic acid is realized.

Description

Technical Field

[0001] The invention relates to the technical field of hydrothermal catalytic biomass and CO2 synergistic conversion to produce high value-added organic acids, and in particular to the application of a bimetallic organic framework material MIL-53 (Fe, Cu) in hydrothermal catalytic biomass and CO2 synergistic conversion to produce high value-added organic acids. Background Art

[0002] With the rapid development of economy and modern industry, the demand for energy in human activities has increased rapidly. At present, traditional fossil energy accounts for about 80% of the global energy structure. The over-reliance on fossil fuels has put humans in the face of the crisis of energy depletion. At the same time, the combustion of fossil fuels is accompanied by the emission of a large amount of CO2, which has caused environmental problems including global warming. Therefore, the rational use of widely distributed resources in nature and the development of clean and sustainable energy have become one of the problems that humans urgently need to solve. Biomass and CO2, as the two main carbon-based substances on the earth, are green, clean, widely distributed and abundant in reserves, and are ideal carbon resources. The resource utilization of the two to prepare high-value-added chemicals will help establish a healthy earth carbon cycle and make an important contribution to the realization of sustainable development of mankind.

[0003] Metal-organic frameworks are essentially organic-inorganic porous complexes. They are porous materials with a periodic skeleton structure formed by self-assembly of metal centers and organic ligands. They have the advantages of rich and adjustable morphology, high specific surface area, porosity, mild synthesis conditions and simple steps. Therefore, they have certain potential in the synergistic catalytic conversion of biomass and CO2. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an application technology of a simply synthesized bimetallic organic framework material MIL-53 (Fe, Cu) for the synergistic catalytic conversion of biomass and CO2 to produce high value-added organic acids.

[0005] The object of the present invention is to provide an application of a bimetallic organic framework material MIL-53 (Fe, Cu) in the synergistic conversion of biomass and CO2 to produce high value-added organic acids through hydrothermal catalysis.

[0006] The bimetallic organic framework material MIL-53 (Fe, Cu) is synthesized by the following method:

[0007] The iron salt, the copper salt and the organic ligand are mixed and ultrasonicated until they are completely dissolved in the organic solvent to obtain a mixed solution;

[0008] The mixed solution is subjected to a solvothermal reaction to obtain the bimetallic organic framework material MIL-53 (Fe, Cu).

[0009] In some embodiments of the present invention, the iron salt is selected from one or more of ferric chloride, ferric nitrate and ferric sulfate.

[0010] In some embodiments of the present invention, the copper salt is selected from one or more of copper chloride, copper nitrate, and copper sulfate.

[0011] In some embodiments of the present invention, the organic ligand is selected from terephthalic acid; and the organic solvent is selected from N,N-methyleneformamide.

[0012] In some embodiments of the present invention, the molar ratio of the iron salt to the copper salt is 1:(0.2-0.3). Adding too much or too little copper salt will result in a significant reduction in the yield of high value-added organic acid.

[0013] In some embodiments of the present invention, the molar ratio of the sum of the iron salt and the copper salt to terephthalic acid is 1:(0.5-1.5).

[0014] In some embodiments of the present invention, the solvothermal reaction is carried out at a temperature of 120° C.-180° C. and for a time of 12 h-18 h.

[0015] In some embodiments of the present invention, the bimetallic organic framework material MIL-53 (Fe, Cu) is further included in the steps of washing and drying, wherein the washing method is to use detergents - N,N-methyleneformamide, anhydrous ethanol, and deionized water for 2-4 times respectively in sequence; and the drying method is vacuum drying at a temperature of 60°C-100°C and a time of 9h-15h.

[0016] In some embodiments of the present invention, the biomass includes one or more of glucose, cellulose, and cotton straw.

[0017] In some embodiments of the present invention, the CO2 is NaHCO3 as a solid source.

[0018] In some embodiments of the present invention, the addition amount of the bimetallic organic framework material MIL-53 (Fe, Cu) is 20 mg-80 mg.

[0019] The mass ratio of the biomass to NaHCO3 is 1:(1-6);

[0020] The temperature of the hydrothermal reaction is 220° C.-280° C.; and the time is 0 h-5 h.

[0021] In some embodiments of the present invention, the high value-added organic acid includes formic acid, acetic acid, and lactic acid.

[0022] The bimetallic organic framework material MIL-53 (Fe, Cu) was synthesized by introducing transition metal Cu by element substitution method and applied to the hydrothermal catalysis of biomass and CO2 synergistic conversion to produce high value-added organic acids. The bimetallic organic framework material MIL-53 (Fe, Cu) accelerates the hydrolysis of biomass-derived carbohydrates-cellulose into glucose, and then promotes the isomerization of glucose into fructose, the reverse alcohol condensation of fructose to glyceraldehyde, and the cleavage of glyceraldehyde to produce formaldehyde and ethanolaldehyde in the cascade reaction process, and then oxidizes and reduces with CO2 solid source-NaHCO3 to produce high value-added organic acids; on the other hand, NaHCO3 is reduced to formic acid by hydrogen production through glucose cracking water; finally, the synergistic catalytic conversion of biomass and CO2 into high value-added organic acids is achieved.

[0023] The above technical solution of the present invention has the following advantages compared with the prior art:

[0024] The present invention provides a simple method for synthesizing a bimetallic organic framework material MIL-53 (Fe, Cu). The method is easy to operate, low in cost, has conditions close to large-scale production and application, and has important practical significance.

[0025] The bimetallic organic framework material MIL-53 (Fe, Cu) synthesized by the method of the present invention is applied to the hydrothermal catalytic conversion of biomass and CO2 to produce high value-added organic acids. The bimetallic organic framework material MIL-53 (Fe, Cu) accelerates the hydrolysis of biomass-derived carbohydrates-cellulose into glucose, and then promotes the isomerization of glucose into fructose, the reverse alcohol-aldehyde condensation of fructose to glyceraldehyde, and the cleavage of glyceraldehyde to produce formaldehyde and ethanolaldehyde in the cascade reaction process, and then oxidizes and reduces with the CO2 solid source-NaHCO3 to produce high value-added organic acids; on the other hand, NaHCO3 is reduced to formic acid by hydrogen production through the decomposition of glucose into water; finally, the synergistic catalytic conversion of biomass and CO2 into high value-added organic acids is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 The figure is a simplified process flow chart for synthesizing the bimetallic organic framework material MIL-53 (Fe, Cu) according to the present invention.

[0028] Figure 2 This is the morphology and element distribution diagram of the bimetallic organic framework material MIL-53 (Fe, Cu) obtained in Example 1 of the present invention.

[0029] Figure 3This is the effect of the addition amount of the organic framework material MIL-53 (Fe, Cu) on the yield of high value-added organic acids during the hydrothermal catalytic synergistic conversion of cellulose and NaHCO3 in the present invention.

[0030] Figure 4 It is a time series diagram of the yield of high value-added organic acid under the action of the bimetallic organic framework material MIL-53 (Fe, Cu) during the hydrothermal catalytic synergistic conversion of cellulose and NaHCO3 in the present invention.

[0031] Figure 5 This is a time gradient diagram of the concentration of key intermediate products under the action of the bimetallic organic framework material MIL-53 (Fe, Cu) during the hydrothermal catalytic synergistic conversion of cellulose and NaHCO3 in the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0033] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] Example 1

[0038] This embodiment provides a method for synthesizing a bimetallic organic framework material MIL-53 (Fe, Cu), the steps of which are as follows:

[0039] Step 1: 2 mmol of ferric chloride, 0.5 mmol of copper chloride and 2.5 mmol of terephthalic acid were mixed and sonicated until completely dissolved in 50 mL of N,N-methyleneformamide.

[0040] Step 2: Place the above mixed solution in a stainless steel reactor lined with 100 mL polytetrafluoroethylene liner and perform solvent thermal reaction at 150° C. for 15 h.

[0041] Step 3: After cooling to room temperature, wash with N,N-methyleneformamide, anhydrous ethanol, and deionized water three times in sequence and vacuum dry at 80°C for 12 hours to obtain the bimetallic organic framework material MIL-53 (Fe, Cu). The obtained bimetallic organic framework material MIL-53 (Fe, Cu) was structurally characterized. Figure 2 .like Figure 2 As shown in (a), the bimetallic organic framework material MIL-53(Fe,Cu) exhibits a spindle-shaped structure with a smooth surface. Figure 2 (bd) Figures show that the Cu element is integrated into the framework and is evenly distributed with the Fe element throughout the structure, indicating the successful synthesis of the bimetallic organic framework material MIL-53(Fe,Cu).

[0042] Example 2

[0043] This embodiment provides an application method of a bimetallic organic framework material MIL-53 (Fe, Cu) hydrothermally catalyzing the synergistic conversion of biomass and CO2 to produce high value-added organic acids, the steps of which are as follows:

[0044] Step 1: Ultrasonicate 50 mg-250 mg of bimetallic organic framework material MIL-53 (Fe, Cu) and 81 mg-324 mg of biomass until they are uniformly dispersed in 10 mL of 0.1 M-0.5 M NaHCO3 solution.

[0045] Step 2: Transfer the above mixed system to a stainless steel reactor lined with a 50 mL polytetrafluoroethylene liner, and perform a hydrothermal reaction at 190° C.-250° C. for 0 h-5 h.

[0046] Step 3: After the reaction is completed, the mixture is immediately quenched in an ice-water bath. After cooling to room temperature, the supernatant is diluted and filtered through a 0.22 μm aqueous filter membrane and stored in a brown liquid vial.

[0047] Step 4: Use high performance liquid chromatography to perform quantitative testing of high value-added organic acids and key intermediates.

[0048] Application Example 1

[0049] Effect of the addition amount of bimetallic organic framework material MIL-53 (Fe, Cu) on the yield of high value-added organic acids during the hydrothermal catalytic synergistic conversion of cellulose and NaHCO3:

[0050] The bimetallic organic framework material MIL-53 (Fe, Cu) with different addition amounts obtained in Example 1 and 81 mg of cellulose were ultrasonically dispersed in 10 mL of 0.4 mol / L NaHCO3 solution, and then transferred to a stainless steel reactor lined with 50 mL of polytetrafluoroethylene liner for hydrothermal reaction at 250°C for 2 h. After cooling to room temperature, the mixture was centrifuged and the supernatant was analyzed by liquid chromatography. The yield of the obtained high value-added organic acid varied with the addition amount of the bimetallic organic framework material MIL-53 (Fe, Cu) as shown in FIG. Figure 3 shown.

[0051] from Figure 3 It can be seen that the yield of high value-added organic acids gradually decreases with the increase of the addition amount of bimetallic organic framework material MIL-53 (Fe, Cu). When the addition amount is 50 mg, the total yield of high value-added organic acids is the highest, which is 54.7%, including 10.6% formic acid, 23.0% acetic acid, and 23.5% lactic acid. The results show that the bimetallic organic framework material MIL-53 (Fe, Cu) exhibits the best catalytic effect at low addition amount, indicating that it has strong catalytic performance in catalyzing the synergistic conversion of biomass and CO2; and with the increase of the addition amount of bimetallic organic framework material MIL-53 (Fe, Cu), the yield of high value-added organic acids gradually decreases, which is attributed to the fact that too much bimetallic organic framework material MIL-53 (Fe, Cu) is not conducive to the uniform and sufficient contact between the reaction substrate and the catalytic active sites, thereby inhibiting the catalytic reaction and resulting in a decrease in the yield of organic acids.

[0052] Application Example 2

[0053] Changes in the yield of high value-added organic acids with reaction time during the hydrothermal catalytic synergistic conversion of cellulose and NaHCO3 under the action of the bimetallic organic framework material MIL-53 (Fe, Cu):

[0054] 50 mg of the bimetallic organic framework material MIL-53 (Fe, Cu) obtained in Example 1 and 81 mg of cellulose were ultrasonically dispersed in 10 mL of 0.4 mol / L NaHCO3 solution, and transferred to a stainless steel reactor lined with 50 mL of polytetrafluoroethylene, and hydrothermally reacted at 250°C for 0 h-5 h (except that the bimetallic organic framework material MIL-53 (Fe, Cu) was not added to the control group, and other reaction conditions were the same as those of this group). After cooling to room temperature, centrifugation was performed and the supernatant was analyzed by liquid chromatography. The yield of the obtained high value-added organic acid changed with the reaction time as shown in the following figure: Figure 4 shown.

[0055] from Figure 4 It can be seen that with the extension of reaction time, the yield of high value-added organic acids showed an increasing trend with or without the action of catalytic materials; however, after the bimetallic organic framework material MIL-53 (Fe, Cu) was introduced into the catalytic reaction system, the yield of high value-added organic acids was significantly improved, and the yield of acetic acid reached a maximum of 26.4% at 3 hours, and the yields of formic acid, lactic acid and the total yield of high value-added organic acids all reached a maximum at 4 hours. At this time, compared with the absence of catalytic materials, the yield of high value-added organic acids was significantly improved, and the total yield of high value-added organic acids was 77.4%, of which the yield of formic acid was 15.9%, the yield of acetic acid was 23.9%, and the yield of lactic acid was 37.6%, indicating that the bimetallic organic framework material MIL-53 (Fe, Cu) promoted the synergistic catalytic conversion of cellulose and NaHCO3 into high value-added organic acids.

[0056] Application Example 3

[0057] The concentration of key intermediates changes with reaction time during the hydrothermal catalytic synergistic conversion of cellulose and NaHCO3 under the action of the bimetallic organic framework material MIL-53 (Fe, Cu).

[0058] 50 mg of the bimetallic organic framework material MIL-53 (Fe, Cu) obtained in Example 1 and 81 mg of cellulose were ultrasonically dispersed in 10 mL of 0.4 mol / L NaHCO3 solution, and transferred to a stainless steel reactor lined with 50 mL of polytetrafluoroethylene liner, and hydrothermally reacted at 250°C for 0 h-5 h (except that the bimetallic organic framework material MIL-53 (Fe, Cu) was not added to the control group, and other reaction conditions were the same as those of this group). After cooling to room temperature, centrifugation was performed and the supernatant was analyzed by liquid chromatography. The concentration of the obtained key intermediate product changed with the reaction time as shown in the following figure: Figure 5 shown.

[0059] Depend on Figure 5 As shown in Figure (a), when the reaction time is 0h and no catalytic material is added, no glucose is produced in the reaction solution. However, after the bimetallic organic framework material MIL-53 (Fe, Cu) is introduced into the catalytic reaction system, glucose is produced in the reaction solution at a high concentration, indicating that the bimetallic organic framework material MIL-53 (Fe, Cu) accelerates the hydrolysis process of cellulose to glucose. Figure 5 (a) with Figure 5(b) Under the action of the bimetallic organic framework material MIL-53 (Fe, Cu), the overall glucose concentration was at a low level while the overall fructose concentration was at a high level, indicating that the bimetallic organic framework material MIL-53 (Fe, Cu) promoted the isomerization of glucose into fructose. In addition, it was observed that the fructose concentration dropped sharply within the reaction time period of 1h-3h. Combined with the increase in lactic acid yield, it was proved that the bimetallic organic framework material MIL-53 (Fe, Cu) promoted the retro-aldol condensation of fructose to glyceraldehyde. Figure 5 (c) Compared with the case without adding catalytic materials, after adding the bimetallic organic framework material MIL-53(Fe,Cu), the concentration of ethanolaldehyde in the reaction solution was higher throughout the reaction process, indicating that the bimetallic organic framework material MIL-53(Fe,Cu) broke the bonds of glyceraldehyde into formaldehyde and ethanolaldehyde, and then synergistically transformed with NaHCO3 to produce high value-added organic acids.

[0060] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. Application of a bimetallic organic framework material MIL-53 (Fe, Cu) in the hydrothermal catalytic conversion of biomass and CO2 to produce high value-added organic acids; The bimetallic organic framework material MIL-53 (Fe, Cu) is synthesized by the following method: The iron salt, the copper salt and the organic ligand are mixed and ultrasonicated until they are completely dissolved in the organic solvent to obtain a mixed solution; The mixed solution is subjected to a solvothermal reaction to obtain the bimetallic organic framework material MIL-53 (Fe, Cu).

2. The use according to claim 1, characterized in that: The iron salt includes one or more of ferric chloride, ferric nitrate and ferric sulfate.

3. The use according to claim 1, characterized in that: The copper salt includes one or more of copper chloride, copper nitrate and copper sulfate.

4. The use according to claim 1, characterized in that: The organic ligand is selected from terephthalic acid; The organic solvent is selected from N,N-methyleneformamide.

5. The use according to claim 1, characterized in that: The molar ratio of the iron salt to the copper salt is 1:(0.2-0.3).

6. The use according to claim 1, characterized in that: The molar ratio of the sum of the iron salt and the copper salt to terephthalic acid is 1:(0.5-1.5).

7. The use according to claim 1, characterized in that: The temperature of the solvent thermal reaction is 120° C.-180° C., and the time is 12 h-18 h.

8. The use according to claim 1, characterized in that: The biomass includes one or more of glucose, cellulose, and cotton straw; The CO2 uses NaHCO3 as a solid source.

9. The use according to claim 1, characterized in that: The addition amount of the bimetallic organic framework material MIL-53 (Fe, Cu) is 20mg-80mg; The mass ratio of the biomass to NaHCO3 is 1:(1-6); The temperature of the hydrothermal reaction is 220° C.-280° C.; and the time is 0 h-5 h.

10. The use according to claim 1, characterized in that: The high value-added organic acids include formic acid, acetic acid and lactic acid.

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