Niobium-silicon-carbon metal catalyst, preparation method and application of niobium-silicon-carbon metal catalyst in production of aromatic hydrocarbon products from lignin oil

Abstract

The invention discloses a niobium-silicon-carbon metal catalyst, a preparation method and application of the niobium-silicon-carbon metal catalyst in production of aromatic hydrocarbon products from lignin oil, the niobium-silicon-carbon metal catalyst takes niobium-silicon-carbon as a carrier, the surface of the niobium-silicon-carbon metal catalyst is loaded with metal ruthenium, the niobium-silicon-carbon has a layered porous structure, and Nb-TiO2 nanoparticles are uniformly distributed in a porous carbon matrix. According to the invention, lignin oil is adopted as a raw material, and selective hydrodeoxygenation is carried out under the action of a niobium-silicon-carbon metal catalyst so as to obtain aromatic hydrocarbon products mainly containing propylbenzene and ethylbenzene. The niobium-silicon-carbon metal catalyst disclosed by the invention can be used for catalyzing hydrodeoxygenation of lignin oil to generate aromatic hydrocarbon with high selectivity, and has the advantages of good performance, stable structure, low cost, single product, few byproducts, simplicity in separation and capability of reducing the energy consumption of separation. Particularly, the problem of low selectivity of propylbenzene generated by hydrodeoxygenation of lignin oil can be effectively solved. In addition, the aromatic hydrocarbon compound is an important chemical product, is wide and diversified in application range, and promotes sustainable development in the fields of chemical industry, medicine, materials and the like.

Description

Technical Field

[0001] The present invention relates to a niobium-silicon-carbon metal catalyst, a preparation method thereof, and an application in the production of aromatic hydrocarbons from lignin oil, and particularly relates to a catalyst in which ruthenium metal is supported on niobium-silicon-carbon, a preparation method thereof, and an application in the hydrodeoxygenation reaction of lignin oil, belonging to the research field of synthesizing chemicals from lignin. Background Art

[0002] The predatory exploitation and utilization of fossil energy by humans not only lead to the increasing depletion of energy, but also cause a series of severe environmental problems such as global warming, ocean acidification, and ecological damage. Biomass exists abundantly in nature. Currently, common renewable energy sources mainly include: wind energy, water energy, solar energy, tidal energy, geothermal energy, and biomass energy. Among them, biomass energy is the only renewable organic carbon source in nature, which can be directly converted into important chemical products and liquid fuels, and has important potential value for supplementing and replacing traditional fossil energy. Lignin, as one of the most abundant biomass resources in nature, second only to cellulose in content, is the component with the highest energy density in biomass, accounting for about 10-20% of the mass of lignocellulose. However, the structure of lignin is complex, mainly composed of stubborn C-C and C-O bond crosslinks, and its high-value utilization faces great challenges.

[0003] Traditional hydrodeoxygenation catalysts usually use noble metals (such as palladium, platinum) or transition metals (such as nickel, cobalt) supported on oxide carriers. However, these catalysts have problems such as low activity, poor selectivity, insufficient stability, and high noble metal costs. Traditional catalytic methods usually depolymerize lignin into complex phenolic monomers, and these products are difficult to separate and purify, which limits their application in downstream industries. Therefore, developing a new type of efficient catalytic system to achieve the high-value utilization of lignin, especially converting it into directly utilizable aromatic hydrocarbons or biofuels, has important theoretical value and practical significance. Summary of the Invention

[0004] Object of the Invention: The first object of the present invention is to provide a niobium-silicon-carbon metal catalyst, the second object of the present invention is to provide a preparation method of the niobium-silicon-carbon metal catalyst, and the third object of the present invention is to provide an application of the niobium-silicon-carbon metal catalyst in the preparation of aromatic hydrocarbons by the hydrodeoxygenation reaction of lignin oil.

[0005] Technical Solution: The niobium-silicon-carbon metal catalyst described in the present invention includes niobium-silicon-carbon as a carrier, and ruthenium metal is supported on the surface. Among them, the niobium-silicon-carbon has a hierarchical porous structure, and Nb-TiO2 nanoparticles are uniformly distributed in the porous carbon matrix.

[0006] Further, the preparation of the niobium-silicon-carbon carrier includes the following steps:

[0007] Dissolve glucose, tetrabutyl titanate, niobium oxide, and hydrochloric acid in water, carry out hydrothermal reaction, and carbonize.

[0008] Furthermore, the mass ratio of glucose, tetrabutyl titanate, niobium oxide to hydrochloric acid is (1 - 10):(1 - 10):(0.5 - 10):(0.5 - 10).

[0009] Furthermore, the temperature of the hydrothermal reaction is 100 - 200 °C, and the time of the hydrothermal reaction is 10 - 20 h.

[0010] Furthermore, carbonization is carried out in a nitrogen atmosphere, the carbonization temperature is 600 - 1000 °C, the carbonization time is 1 - 5 h, and the heating rate is 5 - 8 °C / min.

[0011] The preparation method of the niobium silicon carbon metal catalyst of the present invention includes the following steps:

[0012] Prepare a niobium silicon carbon carrier, and load ruthenium metal by the equal-volume impregnation method, the excess impregnation method, or the deposition precipitation method.

[0013] Further, when using the equal-volume impregnation method, the precursor of ruthenium is RuCl3 solution. After impregnation, it is dried at 80 - 100 °C, and then the ruthenium species are reduced by calcination at 400 - 500 °C for more than 4 h in a hydrogen-argon atmosphere with a heating rate of 5 - 8 °C / min to obtain the niobium silicon carbon metal catalyst.

[0014] The present invention also includes the application of the niobium silicon carbon metal catalyst of the present invention in the preparation of aromatics by the hydrodeoxygenation reaction of lignin oil.

[0015] A green catalytic method for the preparation of aromatics by the hydrodeoxygenation reaction of lignin oil includes the following steps:

[0016] Using lignin oil as a raw material, carry out selective hydrodeoxygenation under the action of the niobium silicon carbon metal catalyst of the present invention to obtain aromatic hydrocarbon products.

[0017] Further, the aromatic hydrocarbon products are propylbenzene, ethylbenzene, etc.

[0018] Further, lignin oil is obtained by depolymerizing a substance containing lignin components, and its main chemical composition is a mixture of aromatic compounds mainly composed of syringyl, guaiacyl, and p-hydroxyphenyl.

[0019] Further, the weight ratio of lignin oil to the niobium silicon carbon metal catalyst of the present invention is 1:(0.02 - 1), and preferably, the weight ratio of lignin oil to the catalyst is 1:(0.02 - 0.5).

[0020] Further, the reaction medium includes one or more of water, ionic liquid, and organic solvent, and preferably water.

[0021] Furthermore, the organic solvent is one or more of p-xylene, pentadecane, dodecane, cyclopentane, ethyl acetate, and ethanol. Preferably, the organic solvent is ethyl acetate.

[0022] Further, the weight ratio of lignin oil to the reaction medium is 1:(1 - 50). Preferably, the weight ratio of lignin oil to the reaction medium is 1:(1 - 20).

[0023] Further, the reaction temperature is 200 - 300 °C. Preferably, the reaction temperature is 250 - 300 °C, and the reaction time is 1 - 15 h. Preferably, the reaction time is 4 - 10 h.

[0024] Further, the hydrogen filling pressure is 0.2 - 5 Mpa. Preferably, the pressure of hydrogen filling is 0.5 - 3 MPa.

[0025] Further, the reaction kettle used in the reaction is a four-connected parallel reaction kettle, which can conduct multiple experiments simultaneously and accelerate the R & D process.

[0026] Furthermore, before filling hydrogen into the reaction kettle, the "three-filling and three-releasing" principle is adopted, and hydrogen is used to displace the air in the kettle three times repeatedly.

[0027] The niobium silicon carbon carrier of the present invention has excellent stability and a unique electronic structure. As a carrier, it is used to load ruthenium metal to prepare a catalyst. Among them, ruthenium is an efficient hydrogenation catalyst, and the doping of niobium and carbon increases the oxygen defect vacancy concentration of the carrier, showing excellent activity and selectivity in the deoxygenation reaction. Loading ruthenium on the niobium silicon carbon carrier can not only effectively disperse the active sites and improve the catalytic efficiency, but also optimize the reaction path through the synergistic effect between the two, reduce the generation of by-products, and thus realize the efficient conversion of lignin oil. In addition, this method conforms to the principles of green chemistry, reduces energy consumption and environmental pollution, and has important application prospects. Based on this, it is of great significance and application value to develop a green catalytic method using ruthenium supported on niobium silicon carbon carrier as a catalyst for the hydrodeoxygenation of lignin oil to produce aromatics. This method can not only efficiently convert lignin oil into high-value-added aromatics, but also reduce the impact on the environment, meet the requirements of sustainable development, and provide a new way for the green and efficient utilization of lignin oil.

[0028] The niobium silicon carbon metal catalytic system of the present invention realizes the preparation of aromatic products such as propylbenzene and ethylbenzene with high added value from lignin oil, and has a high yield. The lignin oil source of the present invention is very wide. Using water as the reaction solvent is very friendly to the environment and saves costs. The hydrogen pressure is only 0.5 - 1 Mpa, and the reaction conditions are relatively mild, having broad application prospects and belonging to the category of green chemistry.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0030] (1) In the niobium-silicon-carbon metal catalyst of the present invention, glucose is used as the carbon source. Glucose is a common and inexpensive organic compound with a wide source. It can decompose and transform into carbon relatively uniformly during the hydrothermal and carbonization processes, providing a rich and stable carbon source for the formation of the carbon support, which is beneficial to controlling the structure and performance of the carbon support.

[0031] (2) The niobium-silicon-carbon metal catalyst of the present invention exhibits excellent performance in the hydrodeoxygenation reaction of catalytic biomass lignin oil, and can selectively generate aromatics with a high selectivity. The yield of aromatics can exceed 90%, and the selectivity for aromatics is as high as 98%. In addition, the catalyst shows excellent cyclic stability, and its activity does not decrease significantly during 5 consecutive reactions, making it suitable for large-scale industrial production and having important practical application prospects.

[0032] (3) In the preparation of aromatics from the hydrodeoxygenation reaction of lignin oil in the present invention, water is used as the reaction medium. As an excellent green solvent, water has the characteristics of being non-toxic, harmless, inexpensive, and having simple and fast post-treatment, and is more in line with the requirements of "green chemistry" as an organic reaction medium.

[0033] (4) The niobium-silicon-carbon metal catalyst of the present invention can selectively catalyze lignin oil to generate aromatics, and has good performance, stable structure, low cost. At the same time, the product is single, the by-products are few, the separation is simple, the safety is high, the energy consumption is low, and it has environmental protection advantages. In particular, it can effectively solve the problem of low selectivity in the hydrodeoxygenation of lignin oil to generate propylbenzene. In addition, aromatic compounds are important chemical products with a wide range of applications, which promotes the sustainable development of chemical, pharmaceutical, material and other fields. Detailed implementation manners

[0034] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0035] Example 1

[0036] The niobium-silicon-carbon composite material was synthesized by the hydrothermal method. 5 g of glucose, 5 g of tetrabutyl titanate, 0.5 g of niobium oxide and 0.5 g of hydrochloric acid were respectively dissolved in 40 ml of water and stirred until homogeneous. The above mixed solution was transferred to a hydrothermal autoclave and maintained at a temperature of 100 °C for 10 h. After the hydrothermal reaction was completed, the obtained product was carbonized under a nitrogen atmosphere at a temperature of 600 °C for 1 h with a heating rate of 5 °C / min to obtain the niobium-silicon-carbon metal catalyst.

[0037] Example 2

[0038] Different niobium silicon carbon carriers were prepared by the hydrothermal method of Example 1, except that the mass ratios of glucose, tetrabutyl titanate, niobium oxide to hydrochloric acid were different, which were 5:5:4:0.5, 5:5:6:0.5, 5:5:8:0.5, 5:5:10:0.5, 5:5:20:0.5, 2:2:1:1, 3:3:2:0.8, 5:5:8:1, 5:5:8:0.8, 5:5:8:5, 10:10:10:0.5, 10:10:10:1, 10:5:10:0.5, 10:5:10:1, 10:5:0.5:1, 1:1:1:1, 1:1:20:20, 0.5:0.5:0.2:0.2.

[0039] Example 3

[0040] The 5% Ru / Nb2O5-SiO2 catalyst was prepared by the equal-volume impregnation method. Specifically, 0.13 g of ruthenium(III) chloride trihydrate solid was added to 1.9 L of water to form an impregnation solution. After stirring with the niobium-silicon-carbon supports prepared in Examples 1-2 respectively, it was dried in an oven at 100 °C for 12 h. Then the catalyst was placed in a tubular furnace and calcined at 400 °C for 4 h in a hydrogen-argon atmosphere with a heating rate of 5 °C / min. Sixteen groups of 5% Ru / Nb2O5-SiO2-C were obtained and denoted as: 5% Ru / Nb2O5-SiO2-C(5:5:0.5:0.5), 5% Ru / Nb2O5-SiO2-C(5:5:4:0.5), 5% Ru / Nb2O5-SiO2-C(5:5:6:0.5), 5% Ru / Nb2O5-SiO2-C(5:5:8:0.5), 5% Ru / Nb2O5-SiO2-C(5:5:10:0.5), 5% Ru / Nb2O5-SiO2-C(5:5:20:0.5), 5% Ru / Nb2O5-SiO2-C(2:2:1:1), 5% Ru / Nb2O5-SiO2-C(3:3:2:0.8), 5% Ru / Nb2O5-SiO2-C(5:5:8:1), 5% Ru / Nb2O5-SiO2-C(5:5:8:0.8), 5% Ru / Nb2O5-SiO2-C(5:5:8:5), 5% Ru / Nb2O5-SiO2-C(10:10:10:0.5), 5% Ru / Nb2O5-SiO2-C(10:10:10:1), 5% Ru / Nb2O5-SiO2-C(10:5:10:0.5), 5% Ru / Nb2O5-SiO2-C(10:5:10:1), 5% Ru / Nb2O5-SiO2-C(10:5:0.5:1), 5% Ru / Nb2O5-SiO2-C(1:1:1:1), 5% Ru / Nb2O5-SiO2-C(1:1:20:20) and 5% Ru / Nb2O5-SiO2-C(0.5:0.5:0.2:0.2).

[0041] Comparative Example 1

[0042] Catalysts with different supported ruthenium on supports were prepared according to the method of Example 1, except that the supports were titanium dioxide, cerium dioxide, niobium pentoxide, niobium phosphate, niobium-silicon composite (10% Nb2O5 / SiO2), niobium-carbon composite (10% Nb2O5 / C), and niobium-nitrogen composite (10% Nb2O5 / N).

[0043] Among them, the specific process for preparing the niobium-silicon composite material: impregnate the niobium tartrate solution on silica by the equal-volume impregnation method, and the impregnation amount is calculated according to the mass ratio of Nb2O5-SiO2 being 1:9. After drying in an oven at 100 °C for 12 h, it is calcined in a muffle furnace at 500 °C for 3 h to obtain a 10% Nb2O5 / SiO2 support.

[0044] Prepare other supports loaded with 10% Nb2O5 according to the preparation process of the 10% Nb2O5 / SiO2 support, the difference being that silica is changed to activated carbon and o-phenylenediamine respectively, and finally catalysts 10% Nb2O5 / C and 10% Nb2O5 / N are obtained.

[0045] The Ru loading is 5 wt%, impregnate the ruthenium chloride solution on the support by equal volume, and obtain the catalyst precursor after drying in an oven at 100 °C for 12 h. Place the catalyst precursor in a tubular furnace for reduction. The specific process is as follows: 1 g of the catalyst precursor is heated from room temperature of 20 °C to 400 °C in a tubular furnace under a hydrogen-argon atmosphere and kept for 4 h, and finally catalysts 5% Ru / TiO2, 5% Ru / CeO2, 5% Ru / Nb2O5, 5% Ru / NbPO4, 5% Ru / Nb2O5-SiO2, 5% Ru / Nb2O5-C, and 5% Ru / Nb2O5-N are obtained respectively.

[0046] Example 4

[0047] 1. Prepare lignin oil

[0048] The preparation of lignin oil refers to Example 7 in CN109942378A.

[0049] 2. Carry out hydrodeoxygenation to prepare aromatics under the action of a catalyst

[0050] Use the catalysts prepared in Example 3 and Comparative Example 1 to carry out hydrodeoxygenation of lignin oil to prepare aromatics, specifically as follows:

[0051] 0.2 g of lignin oil, 0.01 g of catalyst and 10 mL of ultrapure water were respectively added into a 25 mL four-parallel reactor, and the reaction was carried out for 8 hours under the conditions of a hydrogen partial pressure of 0.5 MPa and a temperature of 250 °C. The reaction products were analyzed qualitatively by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitatively by gas chromatography (GC Agilent 7890A). An HP-5 chromatographic column was used, and the programmed temperature conditions of the chromatographic column were: maintaining at 50 °C for 10 min, rising to 250 °C at a heating rate of 10 °C / min, and maintaining at 250 °C for 5 min. Among them, the calculation formula for the yield is: mass yield of aromatic hydrocarbon mixture (%) = (mass of aromatic hydrocarbon mixture in the product / mass of lignin oil before reaction) × 100%; the calculation formula for the conversion rate of the aromatic hydrocarbon mixture is: mass conversion rate of lignin oil = (1 - mass of lignin oil in the product / mass of lignin oil raw material before reaction) × 100%; the results are shown in Table 1.

[0052] Table 1 Comparison of conversion rates and yields of different supported catalysts

[0053]

[0054]

[0055] As can be seen from Table 1, when the mass ratio of glucose, tetrabutyl titanate, niobium oxide and hydrochloric acid is in the range of (1 - 10):(1 - 10):(0.5 - 10):(0.5 - 10), the conversion rate of the catalyst to lignin oil and the yield of aromatic hydrocarbons are generally high, which can effectively promote the reaction; while outside this range, such as when the mass ratio is too small or too large, the conversion rate of lignin oil and the yield of aromatic hydrocarbons decrease significantly, and the catalytic effect is not good. This indicates that this mass ratio range plays a key role in improving the performance of the catalyst and optimizing the reaction effect. It can also be seen that 5% Ru / Nb2O5-SiO2-C has an advantage in selectively generating aromatic hydrocarbons from lignin oil compared with other catalysts.

[0056] The above specific embodiments are only explanations of the present application, and they do not limit the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A niobium-silicon-carbon metal catalyst, characterized in that, The niobium-silicon-carbon metal catalyst includes niobium-silicon-carbon as the carrier, with metallic ruthenium loaded on the surface. Among them, the niobium-silicon-carbon has a hierarchical porous structure, and Nb-TiO2 nanoparticles are evenly distributed in the porous carbon matrix.

2. The niobium-silicon-carbon metal catalyst according to claim 1, wherein The preparation of the niobium-silicon-carbon carrier includes the following steps: Dissolve glucose, tetrabutyl titanate, niobium oxide, and hydrochloric acid in water, carry out hydrothermal reaction, and carbonize.

3. The niobium silicon carbon metal catalyst according to claim 2, wherein The mass ratio of glucose, tetrabutyl titanate, niobium oxide to hydrochloric acid is (1-10):(1-10):(0.5-10):(0.5-10).

4. The niobium-silicon-carbon metal catalyst according to claim 2, characterized in that, The temperature of the hydrothermal reaction is 100-200 °C, and the time of the hydrothermal reaction is 10-20 h.

5. The niobium-silicon-carbon metal catalyst according to claim 2, characterized in that, Carbonization is carried out in a nitrogen atmosphere, the carbonization temperature is 600-1000 °C, the carbonization time is 1-5 h, and the heating rate is 5-8 °C / min.

6. The preparation method of the niobium-silicon-carbon metal catalyst according to any one of claims 1 to 5, characterized in that, It includes the following steps: Prepare the niobium-silicon-carbon carrier, and load metallic ruthenium by the equal-volume impregnation method, the excess impregnation method or the deposition precipitation method.

7. The preparation method according to claim 6, characterized in that, When using the equal-volume impregnation method, the precursor of ruthenium is RuCl3 solution. After impregnation, it is dried at 80-100 °C, and the ruthenium species are reduced by calcination at 400-500 °C for more than 4 h under a hydrogen-argon atmosphere with a heating rate of 5-8 °C / min to obtain the niobium-silicon-carbon metal catalyst.

8. Application of the niobium-silicon-carbon metal catalyst according to any one of claims 1-5 in the preparation of aromatics by hydrodeoxygenation of lignin oil.

9. A green catalytic method for preparing aromatic hydrocarbons by hydrodeoxygenation reaction of lignin oil, characterized in that, It includes the following steps: Using lignin oil as the raw material, selective hydrodeoxygenation is carried out under the action of the niobium-silicon-carbon metal catalyst according to any one of claims 1-5 to obtain aromatic hydrocarbon products.

10. The catalytic method according to claim 9, characterized in that, The weight ratio of lignin oil to the niobium-silicon-carbon metal catalyst according to any one of claims 1-5 is 1:(0.02-1). The reaction medium includes one or several of water, ionic liquid, and organic solvent. The weight ratio of lignin oil to the reaction medium is 1:(1-50). The reaction temperature is 200-300 °C, the reaction time is 1-15 h, and the filling hydrogen pressure is 0.2-5 MPa.

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