A method for catalytic depolymerization of lignin into phenolic compounds using RuNiZn / Nb2O5 catalyst.

Abstract

This invention belongs to the field of high-value utilization technology of biomass resources, and discloses a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst. The method includes: uniformly mixing the RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water; stirring under hydrogen atmosphere to carry out the depolymerization reaction; after the reaction, cooling to room temperature and performing solid-liquid separation; evaporating the solvent to obtain the hydrogenated depolymerization product containing monophenols. In this invention, the RuNiZn / Nb2O5 catalyst employs a technique of replacing precious metals with various non-precious metals, which improves the catalyst's reactivity and reduces the amount of precious metals used. This increases the yield of lignin depolymerization products, provides milder depolymerization reaction conditions, and ultimately significantly reduces the catalyst preparation cost and the energy cost of the lignin depolymerization process.

Description

Technical Field

[0001] This invention belongs to the field of high-value utilization technology of biomass resources, and specifically relates to a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst. Background Technology

[0002] Biomass is primarily composed of three types of biopolymers: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose, due to their relatively homogeneous structures, have been efficiently converted using advanced technologies to produce fuels such as ethanol, water, and methane, as well as small-molecule chemicals like acetic acid, furfural, and hydroxymethylfurfural. In contrast, lignin exhibits a heterogeneous structure and stable chemical form, making its processing and utilization difficult. Depolymerizing lignin and converting it into high-value chemicals is a challenging process. However, successful utilization of lignin can expand the range of renewable resources for producing chemicals, fuels, and materials, and increase the economic viability of the entire biomass value-added industry.

[0003] From the perspectives of cost, efficiency, and technical reliability, thermochemical methods have greater potential for industrial application in the high-value utilization of lignin. Depending on the processing technology, thermochemical methods can be divided into several types, including high-temperature pyrolysis, hydrogenolysis, gasification, solvent pyrolysis, oxidation, and combustion. Among these, high-temperature pyrolysis and catalytic depolymerization mainly produce liquid phenol monomer products.

[0004] Specifically, high-temperature pyrolysis typically does not require a catalyst. Under high temperature and air conditions, biomass is converted into products such as gas, pyrolysis oil, and coke. Factors affecting the distribution and composition of lignin pyrolysis products include heating rate, pyrolysis temperature, reaction time, reaction pressure, and feedstock characteristics. Based on the heating rate, pyrolysis liquefaction can be classified into slow pyrolysis, medium-speed pyrolysis, and fast pyrolysis. Slow pyrolysis mainly produces coke, medium-speed pyrolysis yields roughly equal amounts of gas, liquid, and solid products, while fast pyrolysis can achieve a liquid product yield of up to 80 wt% at 500℃–600℃. The obtained gas, liquid, and coke can all be used as fuel. For example, Canada developed a pressurized fluidized bed pyrolysis process in the 1980s and conducted research on wood-based biomass. Many research institutions in China are also researching new technologies for high-temperature pyrolysis and liquefaction of biomass.

[0005] To further explain, lignin hydrogenopolymerization is an emerging and promising biorefining method that combines biomass fractionation with the depolymerization and upgrading of lignin, breaking it down into usable fragments. Currently, catalysts used for lignin hydrogenopolymerization consist of both noble and non-noble metals. Noble metals exhibit excellent activation and adsorption properties for hydrogen molecules and are typically supported on high-surface-area and highly dispersed carbon-based catalysts, such as Pd / C, Ru / C, Pt / C, and Ru-ZnO / C. However, noble metals are expensive, and the extensive use of these catalysts significantly increases the cost of lignin depolymerization, thereby reducing the utilization value and potential of lignin conversion. Summary of the Invention

[0006] The purpose of this invention is to provide a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, thereby solving one or more of the aforementioned technical problems. In the technical solution provided by this invention, the RuNiZn / Nb2O5 catalyst employs a technique of replacing precious metals with various non-precious metals, which improves the catalyst's reactivity and reduces the amount of precious metals used. This increases the yield of lignin depolymerization products, moderates the reaction conditions of the depolymerization reaction, and ultimately significantly reduces the catalyst preparation cost and the energy cost of the lignin depolymerization process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, comprising:

[0009] The RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and stirred in a hydrogen atmosphere to carry out a depolymerization reaction.

[0010] After the reaction was completed, the mixture was cooled to room temperature and subjected to solid-liquid separation. After evaporating the solvent, a hydrogenated depolymerization product containing monophenols was obtained.

[0011] A further improvement of the present invention is that,

[0012] In the RuNiZn / Nb2O5 catalyst, the loading of ruthenium is 0.1wt% to 5wt%, the loading of nickel is 0.2wt% to 10wt%, and the loading of zinc is 0.2wt% to 10wt%.

[0013] A further improvement of the present invention is that, in the step of uniformly mixing the RuNiZn / Nb2O5 catalyst, the lignin-containing biomass feedstock, and water,

[0014] Each 30 mL of water corresponds to 0.005 g to 0.1 g of RuNiZn / Nb2O5 catalyst and 0.5 g of lignin-containing biomass feedstock.

[0015] A further improvement of the present invention is that, in the step of carrying out the depolymerization reaction in a hydrogen atmosphere,

[0016] The hydrogen environment is characterized by a hydrogen pressure of 1 MPa to 3 MPa and a temperature of 200°C to 280°C.

[0017] A further improvement of the present invention is that, in the step of carrying out the depolymerization reaction in a hydrogen atmosphere,

[0018] The hydrogen environment is characterized by a hydrogen pressure of 1 MPa to 3 MPa and a temperature of 220°C to 240°C.

[0019] A further improvement of the present invention is that the preparation steps of the RuNiZn / Nb2O5 catalyst include:

[0020] A RuNiZn trimetallic catalyst precursor was obtained by impregnating a pre-prepared impregnation solution on a Nb2O5 support using a wet impregnation method; wherein the impregnation solution was a methanol solution containing RuCl3, Zn(NO3)2 and Ni(NO3)2.

[0021] The obtained RuNiZn trimetallic catalyst precursor was dried and then reduced with hydrogen to obtain the RuNiZn / Nb2O5 catalyst.

[0022] A further improvement of the present invention is that the preparation step of the impregnation solution includes:

[0023] The nickel precursor Ni(NO3)2·6H2O, the ruthenium precursor RuCl3·3H2O, and the zinc precursor Zn(NO3)2·6H2O were placed in methanol solvent to prepare an impregnation solution.

[0024] The impregnation solution contains RuCl3·3H2O at a concentration of 1.3 mg / mL to 64.7 mg / mL, Ni(NO3)2·6H2O at a concentration of 9.9 mg / mL to 495.5 mg / mL, and Zn(NO3)2·6H2O at a concentration of 9.9 mg / mL to 495.5 mg / mL.

[0025] A further improvement of the present invention is that, in the step of impregnating the Nb2O5 support with the pre-prepared impregnation solution using the initial wet impregnation method,

[0026] The mass ratio of the wetting solution to the Nb2O5 support is (1-2):1.

[0027] A further improvement of the present invention is that, in the step of drying the obtained RuNiZn trimetallic catalyst precursor and then reducing it with hydrogen,

[0028] Drying is carried out at a temperature range of 80℃ to 120℃; hydrogen reduction is carried out at a temperature range of 300℃ to 500℃.

[0029] A further improvement of the present invention is that the hydrogenation depolymerization product containing monophenols includes one or more of the following: phenol, 4-ethylguaiacol, 4-propylguaiacol, vanillinone, dihydropineol, dihydrosinol, 4-propyl-2,6-dimethoxyphenol, and 4-ethyl-2,6-dimethoxyphenol.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, specifically a highly efficient scheme for catalyzing the depolymerization of lignin into small molecule compounds. The core of this invention is the use of RuNiZn / Nb2O5 as a catalyst to catalyze the conversion of lignin in primary biomass feedstocks into small molecule compounds. The RuNiZn / Nb2O5 catalyst designed in this invention is a multi-metal catalyst, which enhances the catalyst's acidity and reducing power, thereby improving the catalyst's reactivity and reducing the amount of precious metals used.

[0032] The technical solution of this invention can improve the yield of lignin depolymerization products (specifically, up to 40.6 wt%). The mild depolymerization reaction conditions can avoid the harsh conditions of lignin hydrogenolysis reaction in traditional pyrolysis process, and ultimately greatly reduce the preparation cost of catalyst and the energy cost of lignin depolymerization process. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram illustrating the principle of a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, as provided in an embodiment of the present invention.

[0035] Figure 2 These are XRD patterns of different Nb₂O₅-based catalysts and corresponding XPS patterns of Ru₃p, Ni₂p, and Zn₂p catalysts in embodiments of the present invention; wherein, Figure 2 In the middle (a), the XRD patterns of different Nb2O5-based catalysts are shown. Figure 2 (b) shows the XPS spectrum of Ru3p in the RuNiZn / Nb2O5 catalyst. Figure 2 Image (c) shows the XPS spectrum of Ni2p in the RuNiZn / Nb2O5 catalyst. Figure 2 Image (d) shows the XPS spectrum of Zn2p in the RuNiZn / Nb2O5 catalyst;

[0036] Figure 3 This is a gas phase spectrum of the product after poplar powder depolymerization catalyzed by the catalyst RuNiZn / Nb2O5 in an embodiment of the present invention;

[0037] Figure 4 This is a GCMS mass spectrum of the poplar wood powder depolymerization product catalyzed by the catalyst RuNiZn / Nb2O5 in an embodiment of the present invention; wherein, Figure 4 (a) shows the GCMS mass spectrum of phenol. Figure 4 (b) shows the GCMS mass spectrum of 4-ethylguaiacol. Figure 4 (c) shows the GCMS mass spectrum of 4-propylguaiacol. Figure 4 The middle (d) image shows the GCMS mass spectrum of vanillin. Figure 4 Image (e) shows the GCMS mass spectrum of dihydropinene. Figure 4 (f) is the GCMS mass spectrum of dihydrosinin. Figure 4 (g) is the GCMS mass spectrum of 4-propyl-2,6-dimethoxyphenol. Figure 4 The GCMS mass spectrum of 4-ethyl-2,6-dimethoxyphenol is shown in (h). Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] The present invention will now be described in further detail with reference to the accompanying drawings:

[0041] Please see Figure 1 This invention provides a method for lignin depolymerization catalyzed by a Nb2O5-supported ruthenium-nickel-zinc catalyst, specifically a RuNiZn / Nb2O5 catalyst-catalyzed depolymerization of lignin into phenolic compounds, comprising the following steps:

[0042] The prepared RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and subjected to a depolymerization reaction in a hydrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the solid and liquid were separated. The solvent was evaporated to obtain a hydrogenated depolymerization product containing monophenols.

[0043] The technical solution provided by the embodiments of the present invention uses RuNiZn / Nb2O5 as a catalyst to catalyze the conversion of lignin in primary biomass raw materials into small molecule compounds; wherein, the RuNiZn / Nb2O5 catalyst designed in the present invention is a multi-metal catalyst, which enhances the acidity and reduction ability of the catalyst, can improve the reaction activity of the catalyst and reduce the amount of precious metals used (specifically, for example, the amount of Ru used in commercial Ru / C can be reduced from 5 wt% to 1 wt%).

[0044] In a further preferred embodiment of the present invention, the ratio of RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water is as follows: 0.005g to 0.1g of RuNiZn / Nb2O5 catalyst and 0.5g of lignin-containing biomass feedstock per 30mL of water. Further exemplary, catalytic depolymerization is preferably carried out in a stainless steel high-pressure reactor; wherein, after purging hydrogen three times to replace air, hydrogen is continuously introduced to reach the required pressure, preferably 1MPa to 3MPa; the reaction temperature range is 200℃ to 280℃, more preferably 220℃ to 240℃; and the reaction time is 0.5h to 6h, preferably 4h to 6h.

[0045] In this embodiment of the invention, the RuNiZn / Nb2O5 catalyst has a ruthenium loading of 0.1wt% to 5wt%, a nickel loading of 0.2wt% to 10wt%, and a zinc loading of 0.2wt% to 10wt%.

[0046] Further, optionally, the mixing reaction of the biomass raw material, reaction solvent and RuNiZn / Nb2O5 catalyst of the present invention is preferably carried out under stirring conditions, wherein the stirring speed is 600 rpm.

[0047] The technical solution provided by the embodiments of the present invention can improve the yield of lignin depolymerization products (specifically, it can be increased to 40.6 wt%). The mild depolymerization reaction conditions can avoid the harsh conditions of lignin hydrogenolysis reaction in traditional pyrolysis process, and ultimately greatly reduce the preparation cost of catalyst and the energy cost of lignin depolymerization process.

[0048] Specifically, as exemplified in this embodiment of the invention, the method for preparing the RuNiZn / Nb2O5 catalyst includes:

[0049] A RuNiZn trimetallic catalyst precursor was obtained by impregnating Nb2O5 with a methanol solution containing appropriate amounts of RuCl3, Zn(NO3)2 and Ni(NO3)2 using the initial wet impregnation method.

[0050] The RuNiZn trimetallic catalyst precursor was dried at 80℃~120℃ for 12h~36h, and then reduced with hydrogen to obtain RuNiZn / Nb2O5. The hydrogen reduction temperature was 300℃~500℃, and the reaction time was 0.5h~3h. More preferably, the reduction temperature was 400℃, the reaction time was 2h, the hydrogen flow rate was preferably 20mL / min, and the heating rate was preferably 5℃ / min.

[0051] In this embodiment of the invention, the nickel precursor is Ni(NO3)2·6H2O, the ruthenium precursor is RuCl3·3H2O, and the zinc precursor is Zn(NO3)2·6H2O; the solvent of the impregnation solution is preferably methanol; when used, the mass ratio of the impregnation solution to the carrier is (1~2):1; in the impregnation solution, the concentration of RuCl3·3H2O is 1.3mg / mL~64.7mg / mL, the concentration of Ni(NO3)2·6H2O is 9.9mg / mL~495.5mg / mL, and the concentration of Zn(NO3)2·6H2O is 9.9mg / mL~495.5mg / mL.

[0052] The method of this invention prepares products including one or more of phenol, 4-ethylguaiacol, 4-propylguaiacol, vanillinone, dihydropinene, dihydrosinol, 4-propyl-2,6-dimethoxyphenol, and 4-ethyl-2,6-dimethoxyphenol. Explanatoryly, the depolymerization product can be extracted with ethyl acetate, and an internal standard can be added for quantitative and qualitative analysis using GC-MS and GC-FID; the analytical procedure is not particularly limited and can be performed according to procedures well known in the art.

[0053] In summary, the embodiments of the present invention disclose a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, which is a method for lignin catalytic hydrogenation depolymerization. In this method, biomass raw materials, catalyst, and aqueous solvent are mixed and depolymerization is carried out. The designed catalyst enhances the acidity and reducing power of the catalyst, enabling the depolymerization reaction to proceed at a lower temperature and further improving the depolymerization efficiency of lignin.

[0054] Example 1

[0055] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, comprising:

[0056] The RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and stirred in a hydrogen atmosphere to carry out a depolymerization reaction. After the reaction was completed, the mixture was cooled to room temperature and subjected to solid-liquid separation. After evaporating the solvent, a hydrogenated depolymerization product containing monophenols was obtained.

[0057] in,

[0058] In the RuNiZn / Nb2O5 catalyst, the loading of ruthenium is 0.1 wt%, the loading of nickel is 0.2 wt%, and the loading of zinc is 0.2 wt%.

[0059] In the step of uniformly mixing RuNiZn / Nb2O5 catalyst, lignin-containing biomass raw material and water, each 30mL of water corresponds to 0.005g RuNiZn / Nb2O5 catalyst and 0.5g lignin-containing biomass raw material;

[0060] In the step of carrying out the depolymerization reaction in a hydrogen environment, the hydrogen environment is defined as a hydrogen pressure of 1 MPa and a temperature of 200°C.

[0061] Example 2

[0062] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, comprising:

[0063] The RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and stirred in a hydrogen atmosphere to carry out a depolymerization reaction. After the reaction was completed, the mixture was cooled to room temperature and subjected to solid-liquid separation. After evaporating the solvent, a hydrogenated depolymerization product containing monophenols was obtained.

[0064] In the RuNiZn / Nb2O5 catalyst, the loading of ruthenium is 3 wt%, the loading of nickel is 5 wt%, and the loading of zinc is 5 wt%.

[0065] In the step of uniformly mixing RuNiZn / Nb2O5 catalyst, lignin-containing biomass raw material and water, each 30mL of water corresponds to 0.05g RuNiZn / Nb2O5 catalyst and 0.5g lignin-containing biomass raw material;

[0066] In the step of carrying out the depolymerization reaction in a hydrogen environment, the hydrogen environment is defined as a hydrogen pressure of 2 MPa and a temperature of 220°C.

[0067] Example 3

[0068] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, comprising:

[0069] The RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and stirred in a hydrogen atmosphere to carry out a depolymerization reaction. After the reaction was completed, the mixture was cooled to room temperature and subjected to solid-liquid separation. After evaporating the solvent, a hydrogenated depolymerization product containing monophenols was obtained.

[0070] in,

[0071] In the RuNiZn / Nb2O5 catalyst, the loading of ruthenium is 5 wt%, the loading of nickel is 10 wt%, and the loading of zinc is 10 wt%.

[0072] In the step of uniformly mixing RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock and water, each 30mL of water corresponds to 0.1g RuNiZn / Nb2O5 catalyst and 0.5g lignin-containing biomass feedstock;

[0073] In the step of carrying out the depolymerization reaction in a hydrogen environment, the hydrogen environment is defined as a hydrogen pressure of 3 MPa and a temperature of 230°C.

[0074] Example 4

[0075] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, comprising:

[0076] The RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and stirred in a hydrogen atmosphere to carry out a depolymerization reaction. After the reaction was completed, the mixture was cooled to room temperature and subjected to solid-liquid separation. After evaporating the solvent, a hydrogenated depolymerization product containing monophenols was obtained.

[0077] in,

[0078] In the RuNiZn / Nb2O5 catalyst, the loading of ruthenium is 4 wt%, the loading of nickel is 8 wt%, and the loading of zinc is 3 wt%.

[0079] In the step of uniformly mixing RuNiZn / Nb2O5 catalyst, lignin-containing biomass raw material and water, each 30mL of water corresponds to 0.05g RuNiZn / Nb2O5 catalyst and 0.5g lignin-containing biomass raw material;

[0080] In the step of carrying out the depolymerization reaction in a hydrogen environment, the hydrogen environment is defined as a hydrogen pressure of 3 MPa and a temperature of 240°C.

[0081] Example 5

[0082] This invention provides a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst, comprising:

[0083] The RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water were mixed evenly and stirred in a hydrogen atmosphere to carry out a depolymerization reaction. After the reaction was completed, the mixture was cooled to room temperature and subjected to solid-liquid separation. After evaporating the solvent, a hydrogenated depolymerization product containing monophenols was obtained.

[0084] in,

[0085] In the RuNiZn / Nb2O5 catalyst, the loading of ruthenium is 4 wt%, the loading of nickel is 8 wt%, and the loading of zinc is 3 wt%.

[0086] In the step of uniformly mixing RuNiZn / Nb2O5 catalyst, lignin-containing biomass raw material and water, each 30mL of water corresponds to 0.05g RuNiZn / Nb2O5 catalyst and 0.5g lignin-containing biomass raw material;

[0087] In the step of carrying out the depolymerization reaction in a hydrogen environment, the hydrogen environment is defined as a hydrogen pressure of 3 MPa and a temperature of 280°C.

[0088] Example 6

[0089] In this embodiment of the invention, the preparation steps of the RuNiZn / Nb2O5 catalyst include:

[0090] A RuNiZn trimetallic catalyst precursor was obtained by impregnating a pre-prepared impregnation solution on a Nb2O5 support using a wet impregnation method; wherein the impregnation solution was a methanol solution containing RuCl3, Zn(NO3)2 and Ni(NO3)2; the obtained RuNiZn trimetallic catalyst precursor was dried and then reduced with hydrogen to obtain a RuNiZn / Nb2O5 catalyst;

[0091] The impregnation solution preparation steps include: placing the nickel precursor Ni(NO3)2·6H2O, the ruthenium precursor RuCl3·3H2O, and the zinc precursor Zn(NO3)2·6H2O in a methanol solvent to prepare the impregnation solution; in the impregnation solution, the concentration of RuCl3·3H2O is 1.3 mg / mL, the concentration of Ni(NO3)2·6H2O is 9.9 mg / mL, and the concentration of Zn(NO3)2·6H2O is 9.9 mg / mL;

[0092] In the step of impregnating the Nb2O5 support with the pre-obtained impregnation solution using the initial wet impregnation method, the mass ratio of the impregnation solution to the Nb2O5 support is 1:1.

[0093] In the step of drying the obtained RuNiZn trimetallic catalyst precursor and then reducing it with hydrogen, the drying is carried out at 80°C and the hydrogen reduction is carried out at 300°C.

[0094] Example 7

[0095] In this embodiment of the invention, the preparation steps of the RuNiZn / Nb2O5 catalyst include:

[0096] A RuNiZn trimetallic catalyst precursor was obtained by impregnating a pre-prepared impregnation solution on a Nb2O5 support using a wet impregnation method; wherein the impregnation solution was a methanol solution containing RuCl3, Zn(NO3)2 and Ni(NO3)2; the obtained RuNiZn trimetallic catalyst precursor was dried and then reduced with hydrogen to obtain a RuNiZn / Nb2O5 catalyst;

[0097] The impregnation solution is prepared by placing nickel precursor Ni(NO3)2·6H2O, ruthenium precursor RuCl3·3H2O, and zinc precursor Zn(NO3)2·6H2O in methanol solvent to obtain the impregnation solution; in the impregnation solution, the concentration of RuCl3·3H2O is 50 mg / mL, the concentration of Ni(NO3)2·6H2O is 200 mg / mL, and the concentration of Zn(NO3)2·6H2O is 300 mg / mL.

[0098] In the step of impregnating the Nb2O5 support with the pre-obtained impregnation solution using the initial wet impregnation method, the mass ratio of the impregnation solution to the Nb2O5 support is 1.5:1.

[0099] In the step of drying the obtained RuNiZn trimetallic catalyst precursor and then reducing it with hydrogen, the drying is carried out at a temperature of 105°C, and the hydrogen reduction is carried out at a temperature of 400°C.

[0100] Example 8

[0101] In this embodiment of the invention, the preparation steps of the RuNiZn / Nb2O5 catalyst include:

[0102] A RuNiZn trimetallic catalyst precursor was obtained by impregnating a pre-prepared impregnation solution on a Nb2O5 support using a wet impregnation method; wherein the impregnation solution was a methanol solution containing RuCl3, Zn(NO3)2 and Ni(NO3)2; the obtained RuNiZn trimetallic catalyst precursor was dried and then reduced with hydrogen to obtain a RuNiZn / Nb2O5 catalyst;

[0103] The impregnation solution preparation steps include: placing the nickel precursor Ni(NO3)2·6H2O, the ruthenium precursor RuCl3·3H2O, and the zinc precursor Zn(NO3)2·6H2O in a methanol solvent to prepare the impregnation solution; in the impregnation solution, the concentration of RuCl3·3H2O is 64.7 mg / mL, the concentration of Ni(NO3)2·6H2O is 495.5 mg / mL, and the concentration of Zn(NO3)2·6H2O is 495.5 mg / mL;

[0104] In the step of impregnating the Nb2O5 support with the pre-obtained impregnation solution using the initial wet impregnation method, the mass ratio of the impregnation solution to the Nb2O5 support is 2:1.

[0105] In the step of drying the obtained RuNiZn trimetallic catalyst precursor and then reducing it with hydrogen, the drying is carried out at a temperature of 120°C; and the hydrogen reduction is carried out at a temperature of 500°C.

[0106] Example 9

[0107] In this embodiment of the invention,

[0108] The preparation of RuNiZn / Nb2O5, RuNiZn / TiO2, RuNiZn / ZSM-5 and RuNiZn / ZrO2 catalysts includes:

[0109] A RuNiZn-based catalyst was prepared by impregnating 0.5 g of Nb2O5 support with 1 mL of methanol solvent containing 12.9 mg RuCl3·3H2O, 49.5 mg Zn(NO3)2·6H2O, and 49.5 mg Ni(NO3)2·6H2O. The impregnated sample was dried at 105 °C for 24 h and then reduced in H2 stream at 400 °C for 2 h.

[0110] RuNiZn / TiO2, RuNiZn / ZSM-5, and RuNiZn / ZrO2 were prepared using the same method.

[0111] The preparation of Ru / Nb₂O₅, RuNi / Nb₂O₅, RuZn / Nb₂O₅, NiZn / Nb₂O₅, 0.1wt% RuNiZn / Nb₂O₅, and 5wt% RuNiZn / Nb₂O₅ catalysts includes:

[0112] Ru / Nb₂O₅ catalysts were prepared by impregnating 12.9 mg RuCl₃ onto 0.5 g support using the initial wet method; RuNi / Nb₂O₅ catalysts were prepared by impregnating 12.9 mg RuCl₃·3H₂O and 91.0 mg Ni(NO₃)₂·6H₂O; RuZn / Nb₂O₅ catalysts were prepared by impregnating 12.9 mg RuCl₃·3H₂O and 91.0 mg Zn(NO₃)₂·6H₂O; NiZn / Nb₂O₅ catalysts were prepared by impregnating 49.5 mg Zn(NO₃)₂ and 49.5 mg Ni(NO₃)₂; 0.1 wt% RuNiZn / Nb₂O₅ was prepared by impregnating 1.3 mg RuCl₃·3H₂O, 49.5 mg Zn(NO₃)₂·6H₂O, and 49.5 mg Ni(NO₃)₂·6H₂O; and 0.1 wt% RuNiZn / Nb₂O₅ was prepared by impregnating 64.5 mg RuCl₃·3H₂O and 49.5 mg Zn(NO₃)₂·6H₂O. 5wt% RuNiZn / Nb2O5 was prepared by using Zn(NO3)2·6H2O and 49.5 mg Ni(NO3)2·6H2O. The impregnated sample was dried at 105 °C for 24 h and then reduced in H2 at 400 °C for 2 h.

[0113] In this embodiment of the invention, the structures of the prepared Ru / Nb2O5, RuNi / Nb2O5, RuZn / Nb2O5, and RuNiZn / Nb2O5 catalysts were characterized by X-ray diffraction, and the results are as follows: Figure 2As shown in (a), 2θ represents the characteristic diffraction peaks at 22.7° and 46.2°, which are attributed to the characteristic derived peaks of Nb₂O₅. The Nb₂O₅ support in the prepared sample remained unchanged during the metal loading process. Furthermore, the structures of the prepared Ru / Nb₂O₅, RuNi / Nb₂O₅, RuZn / Nb₂O₅, and RuNiZn / Nb₂O₅ catalysts were characterized by X-ray photoelectron spectroscopy, and the results are shown below. Figure 2 As shown in (b) to (d), the Ru 3p, Ni 2p, and Zn 2p spectra demonstrate that Ru, Ni, and Zn exist on the catalyst surface in the forms of elemental Ru, NiO, and ZnO.

[0114] Example 10

[0115] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0116] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The distribution spectrum of the lignin depolymerization products was obtained by gas chromatography as shown in the figure. Figure 3 As shown in the figure. Simultaneously, the reaction solution was analyzed by gas chromatography-mass spectrometry (GC-MS) to detect phenolic compounds in the lignin depolymerization products, and their mass spectra are shown in the figure. Figure 4 As shown in the figure, the yield of phenolic compounds was 40.1 wt%, as detected by gas chromatography.

[0117] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / ZrO2 catalyst includes:

[0118] Poplar wood powder (0.5 g), RuNiZn / ZrO2 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 29.5 wt%.

[0119] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / TiO2 catalyst includes:

[0120] Poplar wood powder (0.5 g), RuNiZn / TiO2 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 32.3 wt%.

[0121] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / ZSM-5 catalyst includes:

[0122] Poplar wood powder (0.5 g), RuNiZn / ZSM-5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 18.8 wt%.

[0123] In this embodiment of the invention, the step of depolymerizing lignin using the Ru / Nb2O5 catalyst includes:

[0124] Poplar wood powder (0.5 g), Ru / Nb₂O₅ catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H₂ to remove air. Finally, 3.0 MPa H₂ was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 19.6 wt%.

[0125] In this embodiment of the invention, the step of depolymerizing lignin using the RuNi / Nb2O5 catalyst includes:

[0126] Poplar wood powder (0.5 g), RuNi / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 27.4 wt%.

[0127] In this embodiment of the invention, the step of depolymerizing lignin using the RuZn / Nb2O5 catalyst includes:

[0128] Poplar wood powder (0.5 g), RuZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 21.0 wt%.

[0129] In this embodiment of the invention, the step of depolymerizing lignin using a Ru / C catalyst includes:

[0130] Poplar wood powder (0.5 g), Ru / C catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 39.0 wt%.

[0131] Based on the above embodiments, it can be seen that the RuNiZn / Nb2O5 technical solution provided by the present invention exhibits better catalytic activity compared to traditional bimetallic catalysts and catalysts with different supports; in addition, it also exhibits better catalytic activity compared to the traditional commercial catalyst Ru / C, and the Ru loading decreases from 5 wt% of Ru / C to 1 wt% of RuNiZn / Nb2O5.

[0132] Example 11

[0133] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0134] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 0.5 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 11.1 wt%.

[0135] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0136] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 1 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 23.9 wt%.

[0137] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0138] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 2 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 33.5 wt%.

[0139] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0140] Catalytic depolymerization of lignin: Poplar powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 40.1 wt%.

[0141] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0142] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 6 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 42.6 wt%.

[0143] Based on the above embodiments, it can be seen that the lignin monomer yield of the reaction system containing RuNiZn / Nb2O5 catalyst will increase with the extension of reaction time, reaching the highest value at 4h. Further extension of reaction time will further increase the monomer yield, but to a limited extent. Considering energy costs, the reaction time can be preferably 4h.

[0144] Example 12

[0145] In this embodiment of the invention, the step of depolymerizing lignin using the NiZn / Nb2O5 catalyst includes:

[0146] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 7.6 wt%.

[0147] In this embodiment of the invention, the step of depolymerizing lignin using a 0.1 wt% RuNiZn / Nb2O5 catalyst includes:

[0148] Catalytic depolymerization of lignin: Poplar powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 27.8 wt%.

[0149] In this embodiment of the invention, the step of depolymerizing lignin using a 5wt% RuNiZn / Nb2O5 catalyst includes:

[0150] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 35.4 wt%.

[0151] Based on the above embodiments, it is evident that the Ru content of the noble metal Ru in the RuNiZn / Nb2O5 catalyst has a significant impact on the lignin monomer yield. The Ru content reaches its highest value at 1 wt%, and then decreases at 5 wt%. Therefore, a Ru content of 1 wt% is preferred.

[0152] Example 13

[0153] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5-0.2wt%Ni catalyst includes:

[0154] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 24.7 wt%.

[0155] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5-10wt%Ni catalyst includes:

[0156] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 29.8 wt%.

[0157] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5-0.2wt%Zn catalyst includes:

[0158] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 33.7 wt%.

[0159] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5-10wt%Zn catalyst includes:

[0160] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 40.5 wt%.

[0161] Based on the above embodiments, it is evident that the Ni and Zn contents in the RuNiZn / Nb2O5 catalyst have a significant impact on the lignin monomer yield. The Ni content decreases when it reaches 10 wt%, while the Zn content shows a slight increase when it reaches 10 wt%. Considering the raw material cost of metals, the Ni and Zn contents are preferably 0.2 wt%.

[0162] Example 14

[0163] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0164] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.005 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 16.7 wt%.

[0165] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0166] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.025 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 31.5 wt%.

[0167] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0168] Poplar wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.1 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 43.0 wt%.

[0169] Based on the above embodiments, it is evident that the amount of RuNiZn / Nb2O5 catalyst significantly promotes the yield of lignin monomers; however, the yield only increases slightly when the catalyst amount increases from 10 wt% to 20 wt%. Considering the catalyst preparation cost, the preferred amount of RuNiZn / Nb2O5 is 10 wt%.

[0170] Example 15

[0171] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0172] Beech wood powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 43.6 wt%.

[0173] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0174] Eucalyptus powder (0.5 g), RuNiZn / Nb2O5 catalyst (0.05 g), and water (30 mL) were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was replaced three times with 1.0 MPa H2 to purge the air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 44.5 wt%.

[0175] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0176] 0.5 g of birch powder, 0.05 g of RuNiZn / Nb2O5 catalyst, and 30 mL of water were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 43.4 wt%.

[0177] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0178] 0.5 g of spruce wood powder, 0.05 g of RuNiZn / Nb2O5 catalyst, and 30 mL of water were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 13.2 wt%.

[0179] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0180] 0.5 g of camphor wood powder, 0.05 g of RuNiZn / Nb2O5 catalyst, and 30 mL of water were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 14.1 wt%.

[0181] In this embodiment of the invention, the step of depolymerizing lignin using the RuNiZn / Nb2O5 catalyst includes:

[0182] 0.5 g of straw powder, 0.05 g of RuNiZn / Nb2O5 catalyst, and 30 mL of water were weighed and added to a 100 mL high-pressure reactor. The reactor was sealed, and the gas inside was purged three times with 1.0 MPa H2 to remove air. Finally, 3.0 MPa H2 was introduced, and the reaction was carried out at 240 °C for 4 h. After the reaction was completed, the reaction solution was removed, an internal standard (naphthalene) was added, and the reaction mixture was filtered. The yield of phenolic compounds was detected by gas chromatography at 24.2 wt%.

[0183] Based on the above examples, it is evident that the RuNiZn / Nb2O5 catalyst significantly promotes the lignin depolymerization reaction of different biomass feedstocks. Therefore, RuNiZn / Nb2O5 demonstrates a significant promoting effect on various biomass feedstocks.

[0184] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method of catalyzing depolymerization of lignin into phenolic compounds by a RuNiZn / Nb2O5 catalyst, characterized in that, The application relates to a method for preparing a monophenol-containing hydrogenolysis depolymerization product from a lignin-containing biomass raw material. The RuNiZn / Nb2O5 catalyst, the lignin-containing biomass raw material and water are uniformly mixed, and a depolymerization reaction is carried out under a hydrogen environment through stirring; After the reaction is completed, cooling is carried out to room temperature, and solid-liquid separation treatment is carried out; after the solvent is evaporated, a monophenol-containing hydrogenolysis depolymerization product is obtained; The RuNiZn / Nb2O5 catalyst has a ruthenium loading of 0.1wt%-5wt%, a nickel loading of 0.2wt%-10wt% and a zinc loading of 0.2wt%-10wt%; In the step of uniformly mixing the RuNiZn / Nb2O5 catalyst, the lignin-containing biomass raw material and water, 0.005g-0.1g of the RuNiZn / Nb2O5 catalyst, 0.5g of the lignin-containing biomass raw material and 30mL of water are used. In the step of carrying out the depolymerization reaction under a hydrogen environment, the hydrogen environment is characterized by a hydrogen pressure of 1MPa-3MPa and a temperature of 200 DEG C-280 DEG C. The preparation step of the RuNiZn / Nb2O5 catalyst comprises the following steps: a preliminary impregnation solution is impregnated on a Nb2O5 carrier by using a preliminary wet impregnation method, so as to obtain a RuNiZn three-metal catalyst precursor; the impregnation solution is a methanol solution containing RuCl3, Zn(NO3)2 and Ni(NO3)2; the obtained RuNiZn three-metal catalyst precursor is dried and treated, and then hydrogen reduction is carried out, so as to obtain the RuNiZn / Nb2O5 catalyst. The monophenol-containing hydrogenolysis depolymerization product comprises one or more of phenol, 4-ethyl guaiacol, 4-propyl guaiacol, vanillylacetone, dihydroconiferyl alcohol, dihydroberberol, 4-propyl-2, 6-dimethoxyphenol and 4-ethyl-2, 6-dimethoxyphenol. In the step of carrying out the depolymerization reaction under a hydrogen environment, 2. The method of claim 1, wherein the RuNiZn / Nb205catalyst catalyzes depolymerization of lignin into phenolic compounds. The hydrogen environment is characterized by a hydrogen pressure of 1MPa-3MPa and a temperature of 220 DEG C-240 DEG C. The preparation step of the impregnation solution comprises the following steps:

3. The method of claim 1, wherein the RuNiZn / Nb2O5catalyst is used to catalyze the depolymerization of lignin into phenolic compounds. The nickel precursor Ni(NO3)2.6H2O, the ruthenium precursor RuCl3.3H2O and the zinc precursor Zn(NO3)2.6H2O are placed in a methanol solvent, and the impregnation solution is obtained by configuration; The concentration of the RuCl3.3H2O in the impregnation solution is 1.3mg / mL-64.7mg / mL, the concentration of the Ni(NO3)2.6H2O is 9.9mg / mL-495.5mg / mL, and the concentration of the Zn(NO3)2.6H2O is 9.9mg / mL-495.5mg / mL. In the step of impregnating the preliminary impregnation solution on the Nb2O5 carrier by using the preliminary wet impregnation method, 4. The method of claim 3, wherein the RuNiZn / Nb2O5catalyst is used to catalyze the depolymerization of lignin into phenolic compounds. The mass ratio of the impregnation solution to the Nb2O5 carrier is (1-2):

1. In the step of drying the obtained RuNiZn three-metal catalyst precursor and then carrying out hydrogen reduction, 5. The method of claim 1, wherein the RuNiZn / Nb2O5catalyst catalyzes depolymerization of lignin into phenolic compounds. Drying is carried out at a temperature of 80 DEG C-120 DEG C, and hydrogen reduction is carried out at a temperature of 300 DEG C-500 DEG C. ​

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