Method for preparing 4-propenyl eugenol by self-hydrogen-supply catalysis of lignocellulose by using monatomic alloy catalyst

Abstract

The invention provides a method for preparing 4-propenyl eugenol by self-hydrogen-supply catalysis of lignocellulose by using a monatomic alloy catalyst, which comprises the following steps: reacting lignocellulose in a water medium at 120-180 DEG C under the action of a catalyst in the absence of exogenous hydrogen to obtain 4-propenyl eugenol, and separating reaction products to obtain cellulose and lignin oil (containing 4-propenyl eugenol, 4-propyl eugenol and the like). The 4-propenyl eugenol can be used for producing bioactive molecules, medicines and materials, and has a wide market prospect. According to the method, an external hydrogenation source is not needed, the loading amount of the noble metal catalyst is low, lignocellulose (hardwood, cork and herbaceous plants) can be stripped and depolymerized in water, and 4-propenyl eugenol with a high additional value and cellulose with an intact structure are obtained.

Description

Technical Field

[0001] The present application relates to the technical field of waste carbon resource utilization, and in particular to a method for preparing 4-propenyl syringol from lignocellulose by using a single-atom alloy catalyst to self-supply hydrogen. Background Art

[0002] Lignocellulose, comprising cellulose (30%–50%), hemicellulose (20%–35%), and lignin (15%–35%), is the most abundant renewable carbon resource on Earth. Efficient and rational fractionation, depolymerization, and upgrading of lignocellulose to produce high-value chemicals, fuels, and functional materials is of paramount importance. Traditionally, lignocellulose fractionation is a carbohydrate-oriented process designed to utilize and protect cellulose, often neglecting the lignin component. The lignin obtained from these processes often possesses a large number of condensed C–C structures, making these inert industrial lignins difficult to further convert and utilize. Lignin is composed of coumarin, coniferyl, and sinapyl alcohols. Utilizing these aromatic compounds to produce high-value downstream chemicals can reduce the consumption of fossil resources. Therefore, the high-value utilization of lignin is crucial in the comprehensive utilization of lignocellulose.

[0003] Current methods for depolymerizing lignocellulose typically require hydrogen (CN107840783A, CN112209975A, CN110511116A), resulting in a waste of hydrogen energy. Furthermore, the reaction temperature is typically above 200°C (CN107840783A), resulting in high energy consumption. Furthermore, the catalyst required for the reaction must contain a high loading of precious metals, resulting in low precious metal utilization efficiency and high costs.

[0004] Therefore, there is an urgent need for a more economical, simple, mild and environmentally friendly method for the comprehensive utilization of lignocellulose. Summary of the Invention

[0005] In view of this, the purpose of this application is to propose a method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst to self-supply hydrogen, so as to achieve the comprehensive utilization of lignocellulose.

[0006] Based on the above objectives, the present application provides a method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst to self-supply hydrogen. The method comprises:

[0007] In the absence of exogenous hydrogen, the wood cellulose dispersed in the water medium reacts at 120-180°C under the action of a catalyst;

[0008] separating the reaction products to obtain cellulose and lignin oil (containing 4-propenyl eugenol, 4-propyl eugenol, 4-ethyl eugenol, 4-propenyl guaiacol, and 4-propyl guaiacol);

[0009] The catalyst comprises a carrier and an active component supported on the carrier, wherein the active component is selected from at least one of platinum, nickel and their alloys; the carrier is selected from at least one of niobium oxide, zirconium oxide, aluminum oxide and titanium oxide, magnesium-aluminum composite material, cobalt-aluminum composite material, zinc-aluminum composite material, iron-aluminum composite material and nickel-aluminum composite material;

[0010] The catalyst is prepared in a step-by-step manner, that is, the carrier is first prepared and then the metal is loaded. The metal is loaded by using an excess impregnation method, a deposition precipitation method, an equal volume impregnation method, etc., preferably an equal volume impregnation method.

[0011] The wood cellulose is selected from at least one of woody plants and herbaceous plants, the woody plants are selected from at least one of birch, beech, poplar, camphor, oak, nanmu, schima superba, walnut, oak, ironwood, maple, teak, pine, fir and cypress; the herbaceous plants are selected from at least one of switchgrass, bamboo, wheat straw, rice straw and corn stalks.

[0012] Furthermore, the active component of the catalyst is at least one of platinum, nickel and platinum-nickel alloy, preferably platinum-nickel alloy.

[0013] Furthermore, in the platinum-nickel alloy catalyst, the mass fraction of nickel in the total amount of the catalyst is 5%, the mass fraction of platinum in the total amount of the catalyst is 0.1-2%, and the mass fraction of platinum is preferably 0.2%.

[0014] Furthermore, the carrier is selected from at least one of niobium oxide, zirconium oxide, aluminum oxide and titanium oxide, magnesium aluminum composite material, cobalt aluminum composite material, zinc aluminum composite material, iron aluminum composite material and nickel aluminum composite material, preferably nickel aluminum composite material.

[0015] Furthermore, the reaction temperature is 120-180°C, preferably 140°C.

[0016] Furthermore, the reaction time is 2-24 hours, preferably 16 hours.

[0017] Furthermore, the weight ratio of the lignocellulose to the catalyst is 1:0.2 to 0.6, preferably 1:0.4.

[0018] The present application prepares a single-atom platinum-nickel alloy catalyst that can selectively reform hemicellulose in an aqueous phase, retaining cellulose and converting lignin into high-value-added 4-propenyl syringol. This process does not require an additional hydrogen source, has warm reaction conditions, high precious metal utilization efficiency, and low catalyst cost, thereby efficiently achieving the comprehensive utilization of wood cellulose. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in this application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 Schematic diagram of the process of preparing 4-propenylsyringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0022] It should be noted that, unless otherwise defined, technical or scientific terms used in the embodiments of this application should have the same ordinary meaning as those understood by persons of ordinary skill in the art to which this application belongs. Words such as "include" or "comprising" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects.

[0023] See also Figure 1 A method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst to self-supply hydrogen comprises:

[0024] Step A: Reaction of lignocellulose dispersed in an aqueous medium at 120-180° C. under the action of a catalyst. The lignocellulose dispersed in an aqueous medium may generally include the following sub-steps:

[0025] A1, crushing the lignocellulose; and

[0026] A2, dispersing the crushed lignocellulose in an aqueous medium.

[0027] Then, in step B, the reaction product is separated to obtain cellulose and lignin oil (containing 4-propenyl eugenol, 4-propyl eugenol, etc.). Usually, ethyl acetate can be used to extract the reaction solution to obtain lignin oil. And gas chromatography-mass spectrometry is performed on the lignin oil to obtain the composition and content of each lignin oil monomer in the lignin oil. Usually, the reaction solution is centrifuged, and the precipitate is a mixture of cellulose and a catalyst, and the catalyst in the mixture can be separated by screening. In this way, the method for preparing 4-propenyl eugenol from cellulose by catalyzing self-hydrogenation of a single-atom alloy catalyst in the embodiment of the present application, for the reaction product, lignin oil can be obtained by simple extraction, cellulose and catalyst can be obtained by centrifugation, and the catalyst can be obtained by further screening, which has the advantages of convenient operation.

[0028] In some embodiments, the resulting catalyst can be reused. It can be calcined, for example, at 500° C., to remove carbon deposits on the catalyst surface, allowing the catalyst to be regenerated, extending its service life, reducing catalyst costs, and improving catalyst efficiency.

[0029] The technical solution of the present invention is further described below with reference to specific implementation methods.

[0030] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0031] Unless otherwise specified, the test materials used in the following examples were purchased from conventional biochemical reagent stores.

[0032] Example 1

[0033] Test materials: lignocellulose: birch; lignocellulose: 0.5 g; solvent: water; solvent mass: 10 g; substrate concentration: 5%;

[0034] Catalyst: 0.2Pt5Ni / NiAl2O4, where the active ingredient is Pt and the carrier is NiAl2O4, with a catalyst mass of 0.2g;

[0035] Experimental conditions: batch reactor; atmospheric pressure nitrogen; reaction temperature: 140℃; reaction time: 12h;

[0036] Experimental method: 0.5g of waste PET plastic was dispersed in 10g of water, and then the dispersion and 0.2g of 0.2Pt5Ni / NiAl2O4 catalyst were respectively put into a 50mL stainless steel high-pressure reactor, sealed, filled with normal pressure nitrogen, and heated to the required temperature of 140°C under rapid stirring. The reaction was stopped after 12 hours, cooled, and lignin oil was extracted. The solid was collected by centrifugation and sieved to obtain the catalyst. The remaining solid part was cellulose.

[0037] Example 2

[0038] The only difference from Example 1 is that the catalyst is 5Ni / NiAl2O4.

[0039] Example 3

[0040] The only difference from Example 1 is that the catalyst is 2Pt / NiAl2O4.

[0041] Example 4

[0042] The only difference from Example 1 is that the catalyst is 0.1Pt5Ni / NiAl2O4.

[0043] Example 5

[0044] The only difference from Example 1 is that the catalyst is 0.5Pt5Ni / NiAl2O4.

[0045] Example 6

[0046] The only difference from Example 1 is that the catalyst is 1Pt5Ni / NiAl2O4.

[0047] Example 7

[0048] The difference from Example 1 is that the catalyst is 2Pt5Ni / NiAl2O4.

[0049] Example 8

[0050] The only difference from Example 1 is that the reaction temperature is 120°C.

[0051] Example 9

[0052] The only difference from Example 1 is that the reaction temperature is 160°C.

[0053] Example 10

[0054] The only difference from Example 1 is that the reaction temperature is 180°C.

[0055] Example 11

[0056] The only difference from Example 1 is that the reaction time is 2 h.

[0057] Example 12

[0058] The only difference from Example 1 is that the reaction time is 4 h.

[0059] Example 13

[0060] The only difference from Example 1 is that the reaction time is 8 h.

[0061] Example 14

[0062] The only difference from Example 1 is that the reaction time is 16 h.

[0063] Example 15

[0064] The only difference from Example 1 is that the reaction time is 24 h.

[0065] Example 16

[0066] The only difference from Example 1 is that the amount of catalyst used is 0.1 g.

[0067] Example 17

[0068] The only difference from Example 1 is that the amount of catalyst used is 0.3 g.

[0069] Results Analysis: Lignin oil was qualitatively and quantitatively analyzed by GC-MS (Agilent 7890A) and GC (Agilent 7890B). The detector was a flame ionization detector (both equipped with an HP-5 capillary column), and tridecane was used as an internal standard for the quantification of the liquid product.

[0070] The test results are shown in Table 1.

[0071] Table 1 The mass yield of lignin oil from depolymerization of lignocellulose without exogenous hydrogen under the action of different catalysts

[0072]

[0073] It can be seen that in Examples 1 to 3, when the wood cellulose is birch, the catalyst carrier is a nickel-aluminum composite material, and the active ingredient is selected from at least one of platinum, nickel and platinum-nickel alloy, preferably a single-atom platinum-nickel alloy is used as the catalyst active ingredient, the selectivity of 4-propenyleugenol in the product can reach 50.5%.

[0074] Furthermore, in the platinum-nickel alloy catalyst, the mass fraction of platinum in the total amount of the catalyst is 0.1-2%, preferably the mass fraction of platinum is 0.2%, and the mass yield of 4-propenylsyringol can reach 19.5%.

[0075] Furthermore, the reaction temperature is 120-180° C., preferably 140° C., the mass yield of lignin oil can reach 38.6%, the mass yield of 4-propenyl syringol can reach 19.5%, and the cellulose retention rate can reach 92%.

[0076] Furthermore, the weight ratio of the lignocellulose to the catalyst is 1:0.3 to 0.6, preferably 1:0.4.

[0077] Furthermore, when the reaction time is 2 to 24 hours, preferably 16 hours, the mass yield of 4-propenyl syringol can reach 23.5%, and the retention rate of cellulose can reach 91%.

[0078] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Within the scope of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0079] While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art in light of the foregoing description.

[0080] The embodiments of the present disclosure are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation, characterized in that: The method comprises: In the absence of exogenous hydrogen, the wood cellulose dispersed in the water medium reacts at 120-180°C under the action of a catalyst; separating the reaction products to obtain cellulose and lignin oil (containing 4-propenyl eugenol, 4-propyl eugenol, 4-ethyl eugenol, 4-propenyl guaiacol, and 4-propyl guaiacol); The catalyst includes a carrier and an active component loaded on the carrier, the active component is selected from at least one of platinum, nickel and platinum-nickel alloy; the carrier is selected from at least one of niobium oxide, zirconium oxide, aluminum oxide and titanium oxide, magnesium-aluminum composite material, cobalt-aluminum composite material, zinc-aluminum composite material, iron-aluminum composite material and nickel-aluminum composite material.

2. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: The wood cellulose is selected from at least one of woody plants and herbaceous plants, the woody plants are selected from at least one of birch, beech, poplar, camphor, oak, nanmu, schima superba, walnut, oak, ironwood, maple, teak, pine, fir and cypress; the herbaceous plants are selected from at least one of switchgrass, bamboo, wheat straw, rice straw and corn stalks.

3. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: The active component of the catalyst is at least one of platinum, nickel and platinum-nickel alloy, preferably platinum-nickel alloy.

4. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: In the platinum-nickel alloy catalyst, the mass fraction of nickel in the total amount of the catalyst is 5%, the mass fraction of platinum in the total amount of the catalyst is 0.1-2%, and the mass fraction of platinum is preferably 0.2%.

5. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: The carrier is selected from at least one of niobium oxide, zirconium oxide, aluminum oxide and titanium oxide, magnesium aluminum composite material, cobalt aluminum composite material, zinc aluminum composite material, iron aluminum composite material and nickel aluminum composite material, preferably nickel aluminum composite material.

6. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: The reaction temperature is 120-180°C, preferably 140°C.

7. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: The reaction time is 2-24 hours, preferably 16 hours.

8. The method for preparing 4-propenyl syringol from lignocellulose using a single-atom alloy catalyst for self-hydrogenation according to claim 1, characterized in that: The weight ratio of the lignocellulose to the catalyst is 1:0.2 to 0.6, preferably 1:0.4.

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