Nickel-based catalyst for preparing hydrocarbon-rich bio-oil through hydrothermal liquefaction and preparation method of nickel-based catalyst

Abstract

The invention relates to a nickel-based catalyst for preparing hydrocarbon-rich bio-oil through hydrothermal liquefaction and a preparation method of the nickel-based catalyst. The nickel-based catalyst comprises a carrier and a nickel-containing active component loaded on the carrier, the carrier comprises a molecular sieve and biomass charcoal; the nickel-containing active component comprises metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel. According to the nickel-based catalyst provided by the invention, the molecular sieve and the biomass charcoal are used as carriers, the active components of the nickel-based catalyst not only comprise metallic nickel, but also comprise the nickel oxide layer formed on the surface of the metallic nickel, and the nickel oxide layer can remarkably improve the catalytic durability of the nickel-based catalyst; finally, the nickel-based catalyst has good stability and catalytic activity when the hydrocarbon-rich bio-oil is prepared through high-pressure hydrothermal liquefaction, so that the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass conversion, and in particular to a nickel-based catalyst for producing hydrocarbon-rich bio-oil by hydrothermal liquefaction and a preparation method thereof. Background Art

[0002] Using hydrothermal liquefaction technology to produce bio-oil as a replacement for traditional gasoline and diesel is a key approach to achieving efficient utilization of biomass resources and reducing dependence on fossil fuels. Hydrothermal liquefaction effectively converts carbon from biomass into liquid fuel. However, conventional bio-oil chemical compositions contain a large number of oxygenated compounds, such as phenols, aldehydes, ketones, esters, and organic acids. This results in an overly complex and easily deteriorating bio-oil composition, complicating downstream separation and purification of the target components and significantly increasing the costs of transporting and applying the bio-oil, thus hindering its industrial application.

[0003] Increasing the content of target hydrocarbon components in bio-oil is an effective means of improving the quality of bio-oil. However, relying on an external hydrogen source or a homogeneous catalyst as a hydrogen donor not only increases the production cost of hydrocarbon-rich bio-oil, but also increases the difficulty of separating the target components after the reaction.

[0004] CN112844466A discloses a green biomass carbon modified molecular sieve supported metal catalyst and its preparation method and application. The preparation method comprises the following steps: (1) adding biochar and molecular sieve to a mixed solvent of ethanol and water, stirring and mixing uniformly to obtain a mixed solution; wherein the biochar is at least one of pine nut shell biochar, rice husk biochar, eucalyptus sawdust biochar and chlorella biochar; (2) adding nickel salt and vanadium salt to the mixed solution obtained in step (1), stirring and mixing uniformly, ultrasonically treating, standing at room temperature for aging, and drying to obtain a catalyst precursor; (3) grinding and sieving the catalyst precursor obtained in step (2), and then reducing it at 450-550°C in a reducing gas atmosphere for 3-5 hours, then heating it to 600-700°C for reduction for 2-4 hours, and cooling it to obtain a green biomass carbon modified molecular sieve supported metal catalyst, which can increase the content of the target product aromatic hydrocarbon BTX.

[0005] In summary, it is necessary to develop an efficient and inexpensive nickel-based catalyst suitable for the hydrothermal liquefaction reaction process, couple the hydrothermal and upgrading processes into a "one-step" production process of in situ catalytic hydrothermal coupled upgrading, and realize the efficient refining of hydrocarbon-rich bio-oil from biomass waste. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a nickel-based catalyst for producing hydrocarbon-rich bio-oil by hydrothermal liquefaction and a preparation method thereof. The nickel-based catalyst uses molecular sieves and biochar as carriers, and its active components include not only metallic nickel but also a nickel oxide layer formed on the surface of the metallic nickel. The nickel oxide layer can significantly improve the catalytic durability of the nickel-based catalyst, ultimately enabling the nickel-based catalyst to have good stability and catalytic activity when preparing hydrocarbon-rich bio-oil by high-pressure hydrothermal liquefaction, thereby increasing the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a nickel-based catalyst comprising a carrier and a nickel-containing active component supported on the carrier;

[0009] The carrier includes molecular sieve and biochar;

[0010] The nickel-containing active component includes metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel.

[0011] The present invention uses molecular sieves and biochar as carriers, and while retaining the rich oxygen-containing functional groups on the surface of the biochar, utilizes the confinement effect of the molecular sieve to inhibit the agglomeration of nano-nickel during high-pressure sintering, thereby improving the stability of the nickel-based catalyst in the high-pressure hydrothermal liquefaction reaction. At the same time, the metallic nickel in its active component serves as a catalytic active center, which can adsorb and activate reactants, reduce the reaction energy barrier, and thus improve the catalytic performance of the catalyst. The nickel oxide layer formed on the surface of the metallic nickel can significantly improve the catalytic durability of the nickel-based catalyst. The metallic nickel and the nickel oxide layer formed on the surface of the metallic nickel have a synergistic effect, ultimately enabling the nickel-based catalyst to have good stability and catalytic activity when preparing hydrocarbon-rich bio-oil through high-pressure hydrothermal liquefaction, thereby increasing the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil.

[0012] It should be noted that the hydrocarbon-rich bio-oil in the present invention refers to bio-oil with a hydrocarbon compound content higher than 50%.

[0013] As a preferred technical solution of the present invention, the mass ratio of the molecular sieve and the biochar is (0.25-4):1, for example, it can be 0.25:1, 0.5:1, 1:1, 2:1, 3:1 or 4:1, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0014] The present invention can balance the acidity and porosity of the carrier by limiting the mass ratio of molecular sieve and biochar (0.25-4):1, and the two can synergistically load nickel, wherein the molecular sieve loads highly dispersed Ni through ion exchange. 2+Biochar anchors nickel through surface oxygen-containing groups, and by limiting the mass ratio of the two, it can be ensured that nickel is both dispersed and stable. Furthermore, when using biomass as raw material to prepare hydrocarbon-rich bio-oil, if the nickel-based catalyst of the present invention is used as a catalyst, the acidic sites of the molecular sieve can promote the deoxygenation reaction of biomass-derived intermediates, reduce the oxygen-containing components (carboxylic acids, ketones) in bio-oil, and improve hydrocarbon selectivity. At the same time, the molecular sieve can selectively adsorb small molecular polar compounds, prolong the residence time of hydrocarbon precursors at the active sites, and promote condensation reactions. Biochar provides a large number of nano-nickel loading sites, disperses nano-Ni particles, and prevents nano-nickel sintering. The mesopores of biochar are conducive to the diffusion of large molecules (such as lignin derivatives), and biochar The surface oxygen-containing functional groups can promote the adsorption of polar intermediates through hydrogen bonds or electrostatic effects, and transfer them to the Ni site for hydrodeoxygenation in a directional manner, thereby ultimately increasing the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil. If the mass ratio is less than 0.25:1, that is, the content of the molecular sieve is too low, it will lead to insufficient acidity, reduced nickel dispersibility, and reduced structural stability. When preparing hydrocarbon-rich bio-oil, the oxygen-containing groups on the surface of the nickel-based catalyst will be lost, resulting in a decrease in the adsorption capacity for polar intermediates, and ultimately a decrease in the hydrodeoxygenation efficiency. If the mass ratio is greater than 4:1, that is, the content of the biochar is too low, this will cause the microporous structure of the molecular sieve to dominate, so that the diffusion of the reactants is hindered, the adsorption of the products is difficult, and the risk of carbon deposition increases. At the same time, the thermal stability of the nickel-based catalyst is reduced.

[0015] Preferably, the silicon-to-aluminum ratio of the molecular sieve is 3 to 4, for example, 3, 3.2, 3.4, 3.6, 3.8 or 4, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0016] The present invention uses molecular sieve and biochar as carriers to prepare a nickel-based catalyst, and limits the silicon-aluminum ratio of the molecular sieve to 3-4 to provide more anchoring points, thereby promoting the uniform dispersion of nickel nanoparticles. At the same time, using the molecular sieve with a silicon-aluminum ratio of 3-4 as the carrier skeleton can prevent the collapse of the high-pressure biochar meso / porous structure, improve the mass transfer performance of the high-pressure reaction substrate, and utilize the confinement effect of the molecular sieve to inhibit the high-pressure sintering and agglomeration of nano-nickel, thereby maintaining the catalytic activity of the nickel-based catalyst in the hydrothermal liquefaction reaction.

[0017] Preferably, the mass ratio of the nickel-containing active component to the carrier in the nickel-based catalyst is (0.1-0.2):1, for example, it can be 0.1:1, 0.12:1, 0.14:1, 0.16:1, 0.18:1 or 0.2:1, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0018] In a second aspect, the present invention provides a method for preparing the nickel-based catalyst according to the first aspect, the preparation method comprising the following steps:

[0019] (1) acid washing the molecular sieve to obtain a modified molecular sieve;

[0020] (2) performing a first mixing of the modified molecular sieve, biomass, and solvent to obtain a mixed material A;

[0021] (3) performing a second mixing of the mixed material A and the nickel salt to obtain a mixed material B, and performing a hydrothermal synthesis reaction on the mixed material B to obtain a mixed material C;

[0022] (4) performing solid-liquid separation on the mixed material C to obtain a solid phase product, and sequentially performing drying, calcining, reducing and passivating treatments on the solid phase product to obtain the nickel-based catalyst.

[0023] The present invention uses molecular sieve and biomass as carrier raw materials to prepare a nickel-based catalyst. First, the molecular sieve is acid-washed to remove part of the aluminum in the molecular sieve to obtain a modified molecular sieve with a silicon-aluminum ratio of 3-4 as a skeleton of the nickel-based catalyst. The biomass, the modified molecular sieve and a solvent are mixed to form a carrier, which is then mixed with an active component nickel salt. Then, a corresponding nickel-based catalyst precursor is prepared through a hydrothermal synthesis reaction. The precursor is sequentially subjected to drying treatment, calcination treatment, reduction treatment and passivation treatment. The drying treatment is performed to remove the solvent in the precursor to prevent structural collapse during subsequent high-temperature treatment. The calcination treatment is performed to convert the nickel salt into nickel oxide to form an active phase skeleton. The nickel oxide is then reduced to metallic nickel through a reduction treatment to give it catalytic activity. Finally, the passivation treatment is performed to form an oxide layer only on the surface of the reduced metallic nickel to prevent spontaneous combustion or deactivation when in contact with air, while retaining most of the nickel element in the form of nickel elemental substance to ensure catalytic activity. Finally, a nickel-based catalyst that can be used for hydrothermal liquefaction to prepare hydrocarbon-rich bio-oil is prepared.

[0024] As a preferred technical solution of the present invention, the molecular sieve includes 3A molecular sieve.

[0025] Preferably, the silicon-to-aluminum ratio of the molecular sieve is 1.5 to 2.5, for example, 1.5, 1.7, 2, 2.3 or 2.5, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0026] Preferably, the acidic solution used in the pickling process includes hydrochloric acid solution and / or sulfuric acid solution.

[0027] Preferably, the molar concentration of the acidic solution is 0.05 to 0.2 mol / L, for example, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L or 0.2 mol / L, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0028] Preferably, the pickling temperature is 50-80°C, for example, 50°C, 60°C, 65°C, 70°C or 80°C, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0029] Preferably, the pickling time is 3 to 5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0030] Preferably, the silicon-aluminum ratio of the modified molecular sieve is 3 to 4, for example, 3, 3.2, 3.5, 3.7 or 4, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0031] As a preferred technical solution of the present invention, the preparation method further comprises pretreating the biomass.

[0032] Preferably, the biomass comprises any one of switchgrass, alfalfa, rice straw, sesbania, corn straw, ginger stalks, wood chips or rice husks, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of switchgrass and rice straw, a combination of switchgrass and corn straw, a combination of wood chips and rice husks, a combination of switchgrass, corn straw and rice husks, a combination of switchgrass, sesbania and corn straw, and a combination of alfalfa, ginger stalks and wood chips.

[0033] Preferably, the pretreatment includes a pulverization process and a drying process performed sequentially.

[0034] Preferably, the pulverization process includes ball milling and / or grinding.

[0035] Preferably, the particle size of the biomass obtained by the pulverization process is 3 to 5 mm, for example, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0036] The present invention grinds the biomass to a particle size of 3 to 5 mm, which can increase the specific surface area of ​​the biomass to provide more anchoring points and promote the uniform dispersion of nickel nanoparticles. At the same time, the surface functional group density of the biomass with a particle size of 3 to 5 mm is high, which can fix Ni through complexation. 2+ , and then metallic nickel is formed through a reduction reaction to improve the loading rate and dispersion of metallic nickel.

[0037] Preferably, the temperature of the drying treatment is 60-100°C, for example, 60°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0038] Preferably, the drying treatment time is 10 to 15 hours, for example, it can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0039] As a preferred technical solution of the present invention, the mass ratio of the modified molecular sieve, biomass and solvent in the first mixing process is (0.25~4):1:(1~5), for example, it can be 0.25:1:1, 0.5:1:5, 1:1:2, 2:1:1, 3:1:5 or 4:1:1, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0040] Preferably, the solvent comprises water.

[0041] Preferably, the first mixing includes a first stirring process and a first ultrasonic process performed sequentially.

[0042] Preferably, the mass ratio of the mixed material A to the nickel salt in the second mixing process is (0.2-0.3):1, for example, it can be 0.2:1, 0.22:1, 0.24:1, 0.26:1, 0.28:1 or 0.3:1, but is not limited to the listed values. Other unlisted values ​​within the above numerical range are also applicable.

[0043] Preferably, the nickel salt comprises nickel nitrate and / or nickel chloride.

[0044] Preferably, the second mixing comprises a second stirring process and a second ultrasonic process performed sequentially.

[0045] Preferably, the rotation speed of the first stirring process and the second stirring process is independently 300 to 500 rpm, for example, it can be 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0046] Preferably, the time for the first stirring treatment and the second stirring treatment is independently 10 to 30 minutes, for example, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0047] Preferably, the power of the first ultrasonic treatment and the second ultrasonic treatment is independently 200-400W, for example, 200W, 250W, 300W, 350W or 400W, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0048] Preferably, the time of the first ultrasonic treatment and the second ultrasonic treatment is independently 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0049] As a preferred technical solution of the present invention, the temperature of the hydrothermal synthesis reaction is 160-200°C, for example, it can be 160°C, 170°C, 180°C, 190°C or 200°C, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0050] Preferably, the pressure of the hydrothermal synthesis reaction is 1.5-2.5 MPa, for example, 1.5 MPa, 1.7 MPa, 2 MPa, 2.3 MPa or 2.5 MPa, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0051] Preferably, the hydrothermal synthesis reaction time is 10 to 15 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0052] Preferably, the solid-liquid separation treatment includes centrifugation and / or filtration.

[0053] Preferably, the rotation speed of the centrifugal treatment is 6000-10000 r / min, for example, it can be 6000 r / min, 7000 r / min, 8000 r / min, 9000 r / min or 10000 r / min, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0054] Preferably, the drying temperature is 60-100°C, for example, 60°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values. Other values ​​not listed within the above range are also applicable.

[0055] Preferably, the drying time is 8 to 16 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours or 16 hours, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0056] Preferably, the calcination temperature is 450-550°C, for example, 450°C, 470°C, 490°C, 510°C, 530°C or 550°C, but is not limited to the listed values. Other values ​​not listed within the above range are also applicable.

[0057] Preferably, the calcination treatment time is 0.5 to 1.5 h, for example, 0.5 h, 0.7 h, 1 h, 1.2 h or 1.5 h, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0058] Preferably, the atmosphere of the calcination treatment includes any one or a combination of at least two of nitrogen, helium or argon, wherein typical but non-limiting combinations include: a combination of nitrogen and helium, a combination of nitrogen and argon, a combination of helium and argon, and a combination of nitrogen, helium and argon.

[0059] As a preferred technical solution of the present invention, the temperature of the reduction treatment is 350-450°C, for example, it can be 350°C, 370°C, 390°C, 410°C, 430°C or 450°C, but is not limited to the listed values. Other unlisted values ​​within the above numerical range are also applicable.

[0060] Preferably, the reduction treatment time is 2.5 to 3.5 hours, for example, 2.5 hours, 2.7 hours, 3 hours, 3.2 hours or 3.5 hours, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0061] Preferably, the reducing atmosphere of the reduction treatment includes hydrogen and a first inert gas.

[0062] Preferably, the volume ratio of the hydrogen to the first inert gas is (0.5-1):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0063] Preferably, the temperature of the passivation treatment is 20-25°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C or 25°C, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0064] Preferably, the passivation treatment time is 0.5 to 1.5 h, for example, 0.5 h, 0.7 h, 1 h, 1.2 h or 1.5 h, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0065] Preferably, the passivation atmosphere of the passivation treatment includes oxygen and a second inert gas.

[0066] Preferably, the volume ratio of the oxygen and the first inert gas is (0.01-0.02):1, for example, it can be 0.01:1, 0.012:1, 0.014:1, 0.016:1, 0.018:1 or 0.02:1, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0067] Preferably, the first inert gas and the second inert gas each independently include any one or a combination of at least two of nitrogen, helium or argon, wherein typical but non-limiting combinations include: a combination of nitrogen and helium, a combination of nitrogen and argon, a combination of helium and argon, and a combination of nitrogen, helium and argon.

[0068] Preferably, the flow rates of the reducing atmosphere and the passivating atmosphere are each independently 80 to 120 mL / min, for example, 80 mL / min, 90 mL / min, 100 mL / min, 110 mL / min or 120 mL / min, but are not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0069] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0070] (1) acid washing the molecular sieve to obtain a modified molecular sieve with a silicon-aluminum ratio of 3 to 4;

[0071] (2) pulverizing and drying the biomass in sequence to obtain processed biomass with a particle size of 3 to 5 mm;

[0072] (3) performing a first mixing of the modified molecular sieve, the treated biomass, and the solvent in a mass ratio of (0.25-4):1:(1-5) to obtain a mixed material A;

[0073] (4) performing a second mixing of the mixed material A and the nickel salt in a mass ratio of (0.2-0.3):1 to obtain a mixed material B, and subjecting the mixed material B to a hydrothermal synthesis reaction at 160-200° C. and 1.5-2.5 MPa for 10-15 hours to obtain a mixed material C;

[0074] (5) performing solid-liquid separation on the mixed material C to obtain a solid phase product, and sequentially performing drying, calcining, reducing and passivating on the solid phase product to obtain the nickel-based catalyst;

[0075] There is no particular order in which steps (1) and (2) are performed.

[0076] In a third aspect, the present invention provides a use of the nickel-based catalyst according to the first aspect in the preparation of hydrocarbon-rich bio-oil.

[0077] The nickel-based catalyst provided by the present invention has good stability under high-pressure hydrothermal liquefaction reaction conditions and can be used in the preparation of hydrocarbon-rich bio-oil to increase the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil.

[0078] Compared with the prior art, the present invention has at least the following beneficial effects:

[0079] (1) The nickel-containing active component of the nickel-based catalyst provided by the present invention includes metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel, so that the nickel-based catalyst has good stability and catalytic activity during the hydrothermal liquefaction reaction, and can preferably achieve a hydrocarbon compound content of 83.6% or more in the hydrocarbon-rich bio-oil during the preparation process of the hydrocarbon-rich bio-oil;

[0080] (2) The nickel-based catalyst provided by the present invention is prepared using renewable biomass waste as raw materials, and has the advantages of a wide range of raw material sources, significant cost-effectiveness, and environmental friendliness.

[0081] (3) The preparation method of the nickel-based catalyst provided by the present invention allows an oxide layer to be formed only on the surface of the reduced metallic nickel, thereby preventing spontaneous combustion or deactivation when in contact with air, and retaining most of the nickel element in the form of nickel element to ensure catalytic activity. The preparation method of the present invention is simple and easy to operate, and ultimately produces a nickel-based catalyst that can be used for hydrothermal liquefaction to prepare hydrocarbon-rich bio-oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 This is the XRD spectrum of the nickel-based catalyst provided in Example 1 of the present invention.

[0083] Figure 2 The nickel-based catalyst provided in Example 1 of the present invention is subjected to argon ion (Ar + ) Sputtering etching, XPS change diagram obtained with changing etching time.

[0084] Figure 3 This is the FT-IR graph of the nickel-based catalyst provided in Example 1 of the present invention.

[0085] Figure 4 This is a total ion current diagram of hydrocarbon-rich bio-oil obtained by hydrothermal liquefaction reaction using the nickel-based catalyst provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0086] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0087] Example 1

[0088] This embodiment provides a nickel-based catalyst, which includes a carrier with a mass ratio of 1:0.15 and a nickel-containing active component loaded on the carrier; the carrier includes a molecular sieve (HX-3A-P) and biochar with a mass ratio of 3:1; the molar ratio of silicon oxide to aluminum oxide in the molecular sieve is 3.5, and the nickel-containing active component includes metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel.

[0089] The nickel-based catalyst was subjected to XRD test, XPS test and FT-IR test respectively, and the XRD spectrum, XPS change diagram and FT-IR diagram were obtained as shown in FIG. Figure 1 、 Figure 2 and Figure 3 As shown, from Figure 1 It can be seen that the nickel-based catalyst has peaks corresponding to the 111, 200 and 220 crystal plane indices, that is, the nickel-based catalyst has a crystalline structure. Figure 2 It can be seen that the nickel in the nickel-based catalyst contains not only 0-valent nickel but also +2-valent nickel. Figure 3 It can be seen that nickel-based catalysts have abundant oxygen-containing functional groups such as -OH and -CO.

[0090] This embodiment also provides a method for preparing the nickel-based catalyst, which comprises the following steps:

[0091] (1) Using 0.1 mol / L hydrochloric acid solution at 65 ° C for 4 h, a 3A molecular sieve with a silicon-aluminum ratio of 2 was acid washed in a water bath to obtain a modified molecular sieve with a silicon-aluminum ratio of 3.5;

[0092] (2) ball-milling the rice husk to obtain pulverized rice husk with a particle size of 4 mm, drying the pulverized rice husk at 80° C. for 12 hours to obtain treated rice husk, wherein the moisture content of the treated rice husk is 7.4%;

[0093] (3) mixing the modified molecular sieve, the treated rice husk, and water in a mass ratio of 3:1:2 at a rotation speed of 400 rpm, stirring for 20 minutes, and then performing a first ultrasonic treatment at a power of 300 W for 2 hours to obtain a mixed material A;

[0094] (4) Mixing the mixed material A with nickel nitrate in a mass ratio of 0.25:1 at a rotation speed of 400 rpm and stirring for 20 minutes, then performing a second ultrasonic treatment at a power of 300 W for 2 hours to obtain a mixed material B, and performing a hydrothermal synthesis reaction on the mixed material B at 180° C. and 2 MPa for 12 hours to obtain a mixed material C;

[0095] (5) The mixed material C is centrifuged at a speed of 8000 r / min to obtain a solid phase product, the solid phase product is dried at 80°C for 12 h, the dried sample is calcined at 500°C in a nitrogen atmosphere for 1 h, the calcined sample is reduced at 400°C for 3 h, wherein the reducing atmosphere of the reduction treatment is a mixture of hydrogen and nitrogen with a volume ratio of 0.7:1, and the flow rate of the reducing atmosphere is 100 mL / min, the sample after the reduction treatment is passivated at 25°C for 1 h, wherein the passivation atmosphere of the passivation treatment is a mixture of oxygen and nitrogen with a volume ratio of 0.015:1, and the flow rate of the passivation atmosphere is 100 mL / min, and the nickel-based catalyst is obtained after the passivation treatment;

[0096] There is no particular order in which steps (1) and (2) are performed.

[0097] Example 2

[0098] This embodiment provides a nickel-based catalyst, which includes a carrier with a mass ratio of 1:0.1 and a nickel-containing active component loaded on the carrier; the carrier includes a molecular sieve (HY-3A-P) and biochar with a mass ratio of 0.25:1; the molar ratio of silicon oxide to aluminum oxide in the molecular sieve is 3, and the nickel-containing active component includes metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel.

[0099] This embodiment also provides a method for preparing the nickel-based catalyst, which comprises the following steps:

[0100] (1) Using 0.05 mol / L sulfuric acid solution at 50 ° C for 5 h, a 3A molecular sieve with a silicon-aluminum ratio of 1.5 was acid washed in a water bath to obtain a modified molecular sieve with a silicon-aluminum ratio of 3;

[0101] (2) grinding and crushing the corn straw to obtain crushed corn straw with a particle size of 3 mm, drying the crushed corn straw at 60° C. for 15 hours to obtain processed corn straw, wherein the moisture content of the processed corn straw is 6.5%;

[0102] (3) mixing the modified molecular sieve, the treated corn straw, and water at a mass ratio of 0.25:1:1 at a rotation speed of 300 rpm, stirring for 30 min, and then performing a first ultrasonic treatment at a power of 400 W for 1 h to obtain a mixture A;

[0103] (4) Mixing the mixed material A with nickel chloride in a mass ratio of 0.2:1 at a rotation speed of 500 rpm and stirring for 10 minutes, then performing a second ultrasonic treatment at a power of 200 W for 3 hours to obtain a mixed material B, and performing a hydrothermal synthesis reaction on the mixed material B at 160° C. and 1.5 MPa for 15 hours to obtain a mixed material C;

[0104] (5) The mixed material C is centrifuged at a speed of 6000 r / min to obtain a solid phase product, the solid phase product is dried at 100° C. for 8 h, the dried sample is calcined at 450° C. in a helium atmosphere for 1.5 h, the calcined sample is reduced at 450° C. for 2.5 h, wherein the reducing atmosphere of the reduction treatment is a mixture of hydrogen and helium with a volume ratio of 0.5:1, and the flow rate of the reducing atmosphere is 80 mL / min, the sample after the reduction treatment is passivated at 25° C. for 0.5 h, wherein the passivation atmosphere of the passivation treatment is a mixture of oxygen and argon with a volume ratio of 0.01:1, and the flow rate of the passivation atmosphere is 120 mL / min, and the nickel-based catalyst is obtained after the passivation treatment;

[0105] There is no particular order in which steps (1) and (2) are performed.

[0106] Example 3

[0107] This embodiment provides a nickel-based catalyst, which includes a carrier with a mass ratio of 1:0.2 and a nickel-containing active component loaded on the carrier; the carrier includes a molecular sieve (SQ-3A-P) and biochar with a mass ratio of 4:1; the molar ratio of silicon oxide to aluminum oxide in the molecular sieve is 4, and the nickel-containing active component includes metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel.

[0108] This embodiment also provides a method for preparing the nickel-based catalyst, which comprises the following steps:

[0109] (1) Using 0.2 mol / L hydrochloric acid solution at 80 ° C for 3 h, a 3A molecular sieve with a silicon-aluminum ratio of 2.5 was acid washed in a water bath to obtain a modified molecular sieve with a silicon-aluminum ratio of 4;

[0110] (2) ball milling the switchgrass to obtain a pulverized switchgrass having a particle size of 5 mm, drying the pulverized switchgrass at 100° C. for 10 hours to obtain a processed switchgrass, wherein the processed switchgrass has a moisture content of 8.9%;

[0111] (3) mixing the modified molecular sieve, the treated switchgrass, and water in a mass ratio of 4:1:5 at a rotation speed of 500 rpm, stirring for 10 minutes, and then performing a first ultrasonic treatment at a power of 200 W for 3 hours to obtain a mixed material A;

[0112] (4) Mixing the mixture A with nickel nitrate in a mass ratio of 0.3:1 at a rotation speed of 300 rpm and stirring for 30 min, then performing a second ultrasonic treatment at a power of 400 W for 1 h to obtain a mixture B, and performing a hydrothermal synthesis reaction on the mixture B at 200° C. and 2.5 MPa for 10 h to obtain a mixture C;

[0113] (5) The mixed material C is filtered to obtain a solid phase product, and the solid phase product is dried at 60°C for 16 hours. The dried sample is calcined at 550°C in an argon atmosphere for 0.5 hours. The calcined sample is reduced at 350°C for 3.5 hours, wherein the reducing atmosphere of the reduction treatment is a mixture of hydrogen and argon with a volume ratio of 1:1, and the flow rate of the reducing atmosphere is 120 mL / min. The sample after the reduction treatment is passivated at 20°C for 1.5 hours, wherein the passivation atmosphere of the passivation treatment is a mixture of oxygen and helium with a volume ratio of 0.02:1, and the flow rate of the passivation atmosphere is 80 mL / min. After the passivation treatment, the nickel-based catalyst is obtained;

[0114] There is no particular order in which steps (1) and (2) are performed.

[0115] Example 4

[0116] This embodiment provides a nickel-based catalyst, which differs from Example 1 only in that the mass ratio of the molecular sieve (HX-3A-P) and the biochar is adjusted from 3:1 to 0.1:1, that is, step (3) in the preparation method of the nickel-based catalyst is adjusted to mixing the modified molecular sieve, the treated rice husk and water in a mass ratio of 0.1:1:2 at a rotation speed of 400 rpm, and the rest is the same as Example 1.

[0117] Example 5

[0118] This embodiment provides a nickel-based catalyst, which differs from Example 1 only in that the mass ratio of the molecular sieve (HX-3A-P) and the biochar is adjusted from 3:1 to 5:1, that is, step (3) in the preparation method of the nickel-based catalyst is adjusted to mixing the modified molecular sieve, the treated rice husk and water in a mass ratio of 5:1:2 at a rotation speed of 400 rpm, and the rest is the same as Example 1.

[0119] Example 6

[0120] This embodiment provides a nickel-based catalyst, which is the same as Example 1 except that step (1) is not included and an unmodified molecular sieve with a silicon-aluminum ratio of 2 is directly used in step (3).

[0121] Example 7

[0122] This embodiment provides a nickel-based catalyst, which differs from Example 1 only in that, except that the silicon-aluminum ratio of the modified molecular sieve used in step (3) is 5, that is, step (1) in the preparation method of the nickel-based catalyst is adjusted to use 0.2 mol / L hydrochloric acid solution to water bath pickle 3A molecular sieve (JLOX-3A-P) with a silicon-aluminum ratio of 2 at 65°C for 6 hours to obtain a modified molecular sieve with a silicon-aluminum ratio of 5. The rest is the same as Example 1.

[0123] Example 8

[0124] This embodiment provides a nickel-based catalyst, which differs from Example 1 only in that, except for the ball milling treatment in step (2) of the preparation method to obtain pulverized rice husks with a particle size of 2 mm, the rest is the same as Example 1.

[0125] Example 9

[0126] This embodiment provides a nickel-based catalyst, which differs from Example 1 only in that, except for the pulverization of rice husks with a particle size of 8 mm obtained by ball milling in step (2) of the preparation method, the rest is the same as Example 1.

[0127] Comparative Example 1

[0128] This comparative example provides a nickel-based catalyst, which differs from Example 1 only in that the carrier of the nickel-based catalyst only includes molecular sieve (HX-3A-P) but not biochar, and the mass ratio of the nickel-containing active component to the carrier is kept unchanged, that is, the preparation method of the nickel-based catalyst does not include step (2), and step (3) is adjusted to mixing the modified molecular sieve and water in a mass ratio of 2:1 at a rotation speed of 400 rpm. The rest is the same as Example 1.

[0129] Comparative Example 2

[0130] This comparative example provides a nickel-based catalyst, which differs from Example 1 only in that the carrier of the nickel-based catalyst only includes biochar and does not include molecular sieve (HX-3A-P), and the mass ratio of the nickel-containing active component to the carrier remains unchanged, that is, the preparation method of the nickel-based catalyst does not include step (1), and step (3) is adjusted to mixing the treated rice husks and water in a mass ratio of 2:1 at a rotation speed of 400 rpm. The rest is the same as Example 1.

[0131] Comparative Example 3

[0132] This comparative example provides a nickel-based catalyst, which differs from Example 1 only in that, except that the nickel-containing active component of the nickel-based catalyst only includes metallic nickel but does not include the nickel oxide layer formed on the surface of the metallic nickel, that is, the preparation method of the nickel-based catalyst does not include the passivation treatment in step (5), the rest is the same as Example 1.

[0133] Comparative Example 4

[0134] This comparative example provides a nickel-based catalyst, which differs from Example 1 only in that, except for step (5) of the preparation method of the nickel-based catalyst being adjusted to: the dried sample is calcined at 500°C in a reducing atmosphere for 1 hour, wherein the reducing atmosphere is a mixture of hydrogen and nitrogen with a volume ratio of 0.7:1 and a flow rate of the reducing atmosphere is 100 mL / min; the calcined sample is passivated at 25°C for 1 hour, and the rest is the same as Example 1.

[0135] Comparative Example 5

[0136] This comparative example provides a nickel-based catalyst, which is the same as Example 1 except that the preparation method of the nickel-based catalyst does not include reduction treatment and passivation treatment.

[0137] The characteristics of the nickel-based catalysts corresponding to Examples 4 to 9 of the present invention and Comparative Examples 1 to 5 are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141] Corn straw is used as a raw material to prepare hydrocarbon-rich bio-oil through a hydrothermal liquefaction reaction. 10 g of corn straw is added to a hydrothermal liquefaction reactor, and 0.1 g of the nickel-based catalyst prepared in Examples 1 to 9 and Comparative Examples 1 to 5 and 30 g of water are added respectively. The mixture is purged 6 times under the conditions of a pressure of 1 MPa and a nitrogen purge atmosphere for a total of 48 minutes. After the pressure is released to 0.1 MPa, the temperature is increased to 300° C. at a heating rate of 15° C. / min in a nitrogen atmosphere and maintained for 0.5 hour to perform hydrothermal liquefaction treatment. The stirring speed during the hydrothermal liquefaction treatment is 500 rpm. The mixture is then cooled at a cooling rate of 9° C. / min to 25° C., and the pressure is reduced to 0.1 MPa. A mixture containing hydrocarbon-rich bio-oil is obtained. The mixture containing the hydrocarbon-rich bio-oil obtained above was extracted with toluene at 150° C. to obtain the hydrocarbon-rich bio-oil. The hydrocarbon-rich bio-oil obtained above was analyzed by gas chromatography-mass spectrometry (instrument model: Agilent 7890A). The total ion chromatogram of the hydrocarbon-rich bio-oil in Example 1 is as follows: Figure 4 As shown, the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil was obtained.

[0142] Hydrothermal liquefaction was also performed under the same conditions without the use of a nickel-based catalyst to produce hydrocarbon-rich bio-oil, which was recorded as a blank group. The hydrocarbon compound content in the hydrocarbon-rich bio-oil was calculated. The test results are shown in Table 2.

[0143] Table 2

[0144] Hydrocarbon compound content (%) Blank group 13.5％ Example 1 89.3％ Example 2 83.6％ Example 3 92.5％ Example 4 58.5％ Example 5 67.3％ Example 6 73.2％ Example 7 62.5％ Example 8 72.2％ Example 9 53.5％ Comparative Example 1 34.2％ Comparative Example 2 18.1％ Comparative Example 3 27.4％ Comparative Example 4 19.3％ Comparative Example 5 23.5％

[0145] The test results show that:

[0146] (1) It can be seen from Examples 1 to 3 that the nickel-based catalyst provided by the present invention uses molecular sieves and biochar as carriers, and its active components include not only metallic nickel but also a nickel oxide layer formed on the surface of the metallic nickel. The nickel-based catalyst has good stability and catalytic activity when preparing hydrocarbon-rich bio-oil by high-pressure hydrothermal liquefaction, and can make the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil reach more than 83.6%, which is at least 70% higher than the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil without using a catalyst.

[0147] (2) It can be seen from Examples 1 and 4-5 that the carrier of the nickel-based catalyst in Example 1 includes molecular sieve and biochar in a mass ratio of 3:1, and its corresponding nickel-based catalyst can make the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil reach 89.3% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil; while the carrier of the nickel-based catalyst in Example 4 includes molecular sieve and biochar in a mass ratio of 0.1:1, and its corresponding nickel-based catalyst can make the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil reach 89.3% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil. The content of hydrocarbon compounds in the medium is 58.5%. The carrier of the medium nickel-based catalyst includes molecular sieve and biochar in a mass ratio of 5:1. When the corresponding nickel-based catalyst catalyzes a hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil, the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil can be 67.3%. This shows that the present invention can balance the acidity and porosity of the carrier by limiting the mass ratio of molecular sieve and biochar to 0.25-4:1, and the two can synergistically load nickel, wherein the molecular sieve loads highly dispersed Ni through ion exchange. 2+ Biochar anchors nickel through surface oxygen-containing groups. By limiting the mass ratio of the two, it can ensure that nickel is both dispersed and stable, ultimately increasing the content of hydrocarbon compounds in hydrocarbon-rich bio-oil.

[0148] (3) It can be seen from Examples 1 and 6-7 that the silicon-aluminum ratio of the molecular sieve in the support of the nickel-based catalyst in Example 1 is 3.5, and the corresponding nickel-based catalyst can make the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil reach 89.3% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil; while the silicon-aluminum ratio of the molecular sieve in the support of the nickel-based catalyst in Example 6 is 2, and the corresponding nickel-based catalyst can make the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil reach 73.2% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil; the silicon-aluminum ratio of the molecular sieve in the support of the nickel-based catalyst in Example 7 is 5, and the corresponding nickel-based catalyst can make the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil reach 89.3% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil. When hydrocarbon-rich bio-oil is prepared through a hydrothermal liquefaction reaction, the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil can be made to be 62.5%. This shows that the present invention, by using a molecular sieve with a silicon-aluminum ratio of 3 to 4 as the skeleton of the nickel-based catalyst carrier, can provide more anchoring points and promote the uniform dispersion of nickel nanoparticles. At the same time, using a molecular sieve with a silicon-aluminum ratio of 3 to 4 as the carrier skeleton can prevent the collapse of the meso / porous structure of high-pressure biochar, improve the mass transfer performance of the high-pressure reaction substrate, and utilize the confinement effect of the molecular sieve to inhibit the high-pressure sintering and agglomeration of nano-nickel, thereby maintaining the catalytic activity of the nickel-based catalyst in the hydrothermal liquefaction reaction, and ultimately increasing the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil.

[0149] (4) It can be seen from Examples 1 and 8-9 that, in Example 1, the rice husks obtained after ball milling treatment in step (2) have a particle size of 4 mm, and the corresponding nickel-based catalyst can make the hydrocarbon compound content in the hydrocarbon-rich bio-oil reach 89.3% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil; while in Example 8, the rice husks obtained after ball milling treatment in step (2) have a particle size of 2 mm, and the corresponding nickel-based catalyst can make the hydrocarbon compound content in the hydrocarbon-rich bio-oil reach 72.2% when catalyzing the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil. In Example 9, the rice husks obtained by ball milling in step (2) have a particle size of 8 mm. When the corresponding nickel-based catalyst is used to catalyze the hydrothermal liquefaction reaction to prepare hydrocarbon-rich bio-oil, the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil can be 53.5%. This shows that the present invention can increase the specific surface area of ​​the biomass by pulverizing the biomass to make the particle size of the biomass 3 to 5 mm, thereby providing more anchoring points and promoting the uniform dispersion of nickel nanoparticles. At the same time, the surface functional group density of the biomass with a particle size of 3 to 5 mm is high, and Ni can be fixed by complexation. 2+ , and subsequently metallic nickel is formed through a reduction reaction to increase the loading rate and dispersibility of metallic nickel, ultimately increasing the content of hydrocarbon compounds in hydrocarbon-rich bio-oil.

[0150] (5) It can be seen from Example 1 and Comparative Examples 1-2 that the present invention uses molecular sieves and biochar as carriers, while retaining the rich oxygen-containing functional groups on the surface of the biochar, and utilizes the confinement effect of the molecular sieve to inhibit the agglomeration of nano-nickel during high-pressure sintering, thereby improving the stability of the nickel-based catalyst in the high-pressure hydrothermal liquefaction reaction, and ultimately increasing the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil.

[0151] (6) It can be seen from Example 1 and Comparative Examples 3 to 5 that the nickel-containing active component of the nickel-based catalyst of the present invention contains not only metallic nickel, but also a nickel oxide layer on the surface of the metallic nickel, wherein the metallic nickel serves as a catalytically active center and can adsorb and activate reactants, thereby reducing the reaction energy barrier and improving the catalytic performance of the catalyst. The nickel oxide layer formed on the surface of the metallic nickel can significantly improve the catalytic durability of the nickel-based catalyst. The metallic nickel and the nickel oxide layer formed on the surface of the metallic nickel have a synergistic effect, which ultimately enables the nickel-based catalyst to have good stability and catalytic activity when preparing hydrocarbon-rich bio-oil by high-pressure hydrothermal liquefaction, thereby increasing the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil.

[0152] In summary, the present invention prepares a nickel-based catalyst using molecular sieves and biochar as carriers. At the same time, the active components of the nickel-based catalyst include not only metallic nickel but also a nickel oxide layer formed on the surface of the metallic nickel. The metallic nickel and nickel oxide synergistically improve the catalytic performance of the catalyst, ultimately making the nickel-based catalyst have good stability and catalytic activity when preparing hydrocarbon-rich bio-oil by high-pressure hydrothermal liquefaction, and the content of hydrocarbon compounds in the hydrocarbon-rich bio-oil can reach more than 83.6%.

[0153] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A nickel-based catalyst, characterized in that The nickel-based catalyst comprises a carrier and a nickel-containing active component supported on the carrier; The carrier includes molecular sieve and biochar; The nickel-containing active component includes metallic nickel and a nickel oxide layer formed on the surface of the metallic nickel.

2. The nickel-based catalyst according to claim 1, characterized in that The mass ratio of the molecular sieve and the biochar is (0.25-4):1; Preferably, the silicon to aluminum ratio of the molecular sieve is 3 to 4; Preferably, the mass ratio of the nickel-containing active component to the carrier in the nickel-based catalyst is (0.1-0.2):

1.

3. A method for preparing a nickel-based catalyst according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: (1) acid washing the molecular sieve to obtain a modified molecular sieve; (2) performing a first mixing of the modified molecular sieve, biomass, and solvent to obtain a mixed material A; (3) performing a second mixing of the mixed material A and the nickel salt to obtain a mixed material B, and performing a hydrothermal synthesis reaction on the mixed material B to obtain a mixed material C; (4) performing solid-liquid separation on the mixed material C to obtain a solid phase product, and sequentially performing drying, calcining, reducing and passivating treatments on the solid phase product to obtain the nickel-based catalyst.

4. The preparation method according to claim 3, characterized in that The molecular sieve includes 3A molecular sieve; Preferably, the silicon to aluminum ratio of the molecular sieve is 1.5 to 2.5; Preferably, the acidic solution used in the pickling process includes hydrochloric acid solution and / or sulfuric acid solution; Preferably, the molar concentration of the acidic solution is 0.05 to 0.2 mol / L; Preferably, the pickling temperature is 50-80°C; Preferably, the pickling time is 3 to 5 hours; Preferably, the silicon-aluminum ratio of the modified molecular sieve is 3-4.

5. The preparation method according to claim 3 or 4, characterized in that The preparation method further comprises pretreating the biomass; Preferably, the biomass comprises any one or a combination of at least two of switchgrass, alfalfa, rice grass, sesbania, corn straw, ginger stalks, wood chips or rice husks; Preferably, the pretreatment includes a crushing process and a drying process performed in sequence; Preferably, the pulverization process includes ball milling and / or grinding; Preferably, the particle size of the biomass obtained by the pulverization process is 3 to 5 mm; Preferably, the temperature of the drying treatment is 60-100°C; Preferably, the drying treatment time is 10 to 15 hours.

6. The preparation method according to any one of claims 3 to 5, characterized in that In the first mixing process, the mass ratio of the modified molecular sieve, the biomass and the solvent is (0.25-4):1:(1-5); Preferably, the solvent comprises water; Preferably, the first mixing comprises a first stirring process and a first ultrasonic treatment performed sequentially; Preferably, the mass ratio of the mixed material A to the nickel salt in the second mixing process is (0.2-0.3):1; Preferably, the nickel salt comprises nickel nitrate and / or nickel chloride; Preferably, the second mixing comprises a second stirring process and a second ultrasonic process performed sequentially; Preferably, the rotation speed of the first stirring process and the second stirring process are independently 300 to 500 rpm; Preferably, the time of the first stirring treatment and the second stirring treatment is independently 10 to 30 minutes; Preferably, the power of the first ultrasonic treatment and the second ultrasonic treatment is independently 200-400W; Preferably, the time for the first ultrasonic treatment and the second ultrasonic treatment is independently 1 to 3 hours.

7. The preparation method according to any one of claims 3 to 6, characterized in that The temperature of the hydrothermal synthesis reaction is 160-200°C; Preferably, the pressure of the hydrothermal synthesis reaction is 1.5 to 2.5 MPa; Preferably, the hydrothermal synthesis reaction time is 10 to 15 hours; Preferably, the solid-liquid separation process includes centrifugation and / or filtration; Preferably, the rotation speed of the centrifugal treatment is 6000-10000 r / min; Preferably, the drying temperature is 60-100°C; Preferably, the drying time is 8 to 16 hours; Preferably, the calcination temperature is 450-550°C; Preferably, the calcination treatment time is 0.5 to 1.5 hours; Preferably, the calcination atmosphere includes any one of nitrogen, helium or argon, or a combination of at least two of them.

8. The preparation method according to any one of claims 3 to 7, characterized in that The temperature of the reduction treatment is 350-450°C; Preferably, the reduction treatment time is 2.5 to 3.5 hours; Preferably, the reducing atmosphere of the reduction treatment comprises hydrogen and a first inert gas; Preferably, the volume ratio of the hydrogen gas to the first inert gas is (0.5-1):1; Preferably, the temperature of the passivation treatment is 20-25°C; Preferably, the passivation treatment time is 0.5 to 1.5 hours; Preferably, the passivation atmosphere of the passivation treatment comprises oxygen and a second inert gas; Preferably, the volume ratio of the oxygen and the first inert gas is (0.01-0.02):1; Preferably, the first inert gas and the second inert gas each independently include any one of nitrogen, helium or argon, or a combination of at least two thereof; Preferably, the flow rates of the reducing atmosphere and the passivating atmosphere are each independently 80 to 120 mL / min.

9. The preparation method according to any one of claims 3 to 8, characterized in that The preparation method comprises the following steps: (1) acid washing the molecular sieve to obtain a modified molecular sieve with a silicon-aluminum ratio of 3 to 4; (2) pulverizing and drying the biomass in sequence to obtain processed biomass with a particle size of 3 to 5 mm; (3) performing a first mixing of the modified molecular sieve, the treated biomass, and the solvent in a mass ratio of (0.25-4):1:(1-5) to obtain a mixed material A; (4) performing a second mixing of the mixed material A and the nickel salt in a mass ratio of (0.2-0.3):1 to obtain a mixed material B, and subjecting the mixed material B to a hydrothermal synthesis reaction at 160-200° C. and 1.5-2.5 MPa for 10-15 hours to obtain a mixed material C; (5) performing solid-liquid separation on the mixed material C to obtain a solid phase product, and sequentially performing drying, calcining, reducing and passivating on the solid phase product to obtain the nickel-based catalyst; There is no particular order in which steps (1) and (2) are performed.

10. Use of the nickel-based catalyst according to claim 1 or 2 in the preparation of hydrocarbon-rich bio-oil.

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