Catalyst for catalytic cracking of biomass tar and preparation method thereof

Abstract

The invention relates to the technical field of metal materials, in particular to a catalyst for catalytic cracking of biomass tar and a preparation method of the catalyst, and the catalyst is prepared from the following raw materials in percentage by mass: 5%-30% of NiO, 0.05%-15% of SiO2, 0.05%-10% of IVA group metal oxide and 45%-94.9% of Al2O3. The nickel-based catalyst is a shell catalyst, the active components are uniformly distributed on the surface of the alumina carrier, the core-shell structure effectively inhibits the generation of carbon deposition of the catalyst, and the carbon deposition resistance of the catalyst is improved. The catalyst has high activity, the tar catalytic cracking reaction temperature is reduced, the carbon deposition speed of the catalyst is correspondingly reduced, and the reaction stability of the catalyst is improved.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, and in particular to a catalyst for the catalytic cracking of biomass tar and its preparation method. Background Technology

[0002] During biomass gasification, tar is inevitably generated due to the high volatile content of biomass. Under normal operating conditions, tar in biogas easily clogs delivery pipelines, preventing downstream equipment from operating properly and significantly increasing operating costs. Tar in biomass gas limits the commercialization of biomass gasification. Therefore, finding efficient tar removal methods is of great significance for the development of biomass gasification technology.

[0003] Methods for removing biomass tar are divided into physical and chemical methods. Physical methods mainly include washing, filtration, and cyclone separation. While physical methods have advantages such as low cost and ease of operation, they only separate tar from biomass gas, failing to fully utilize the energy contained in the tar, and can cause secondary environmental pollution. Chemical methods include high-temperature pyrolysis and catalytic pyrolysis. High-temperature pyrolysis requires temperatures above 1000℃ to convert most of the tar, resulting in high energy consumption. Catalytic pyrolysis, at 700-900℃, can break down most of the tar into smaller molecule compounds. Catalytic pyrolysis not only improves fuel gas quality but also reduces secondary pollution.

[0004] In the catalytic cracking process of tar, the catalyst is crucial. Nickel-based catalysts are a commonly used type of tar cracking catalyst. However, existing commercial nickel-based catalysts have the following disadvantages: (1) high production cost, (2) easy carbon deposition at high temperatures, (3) easy sintering at high temperatures, and (4) short lifespan. Patent CN101693204A discloses a method for preparing a catalyst using γ-Al2O3 as a support, NiO as the active component, and La2O3, CeO2, and MgO as promoters. This catalyst uses rare earth elements, resulting in high cost and making it difficult to promote. CN101485989A discloses a method for preparing a coal gas tar cracking catalyst using Ni as the active component, alkaline earth metals or alkali metals as promoters, and Ce and Zr modified γ-Al2O3 as a support. This catalyst lacks high-temperature stability data, making it impossible to determine whether it meets the requirements for industrial application. CN102179247A discloses a method for preparing a hollow spherical nickel-based catalyst for tar catalytic cracking. The catalyst support preparation process of this method is complex and not conducive to industrial application.

[0005] The catalysts described above suffer from high preparation costs, complex preparation processes, and a lack of stability data, which hinders their industrial application. Therefore, developing a low-cost, highly active, highly stable catalyst with a simple preparation process is of great significance. Summary of the Invention

[0006] The technical problem that this invention aims to solve is that existing catalysts have high preparation costs, are prone to carbon deposition and sintering deactivation at high temperatures, and have poor high-temperature stability.

[0007] To address the aforementioned technical problems, in a first aspect, the present invention provides a catalyst for the catalytic cracking of biomass tar, wherein the raw materials for preparing the catalyst comprise, by mass percentage: NiO of 5% to 30% (e.g., 5%, 6%, 10%, 20%, 25%, or 30%), SiO2 of 0.05% to 15% (e.g., 0.05%, 0.1%, 1%, 5%, 10%, or 15%), Group IVA metal oxides of 0.05% to 10% (e.g., 0.05%, 1%, 2%, 8%, or 10%), and Al2O3 of 45% to 94.9% (e.g., 45%, 50%, 70%, 80%, or 94.9%).

[0008] The catalyst provided by this invention is modified with silica and IVA metal oxide. Silica modifies the alumina support, increasing the acidity of the weakly acidic alumina surface, which is beneficial for the catalytic cracking of tar; in addition, the hydrothermal stability of the silica-modified alumina support is enhanced, giving the catalyst anti-sintering ability. The modification effect of IVA metal oxide is: (1) the interaction between IVA metal oxide and nickel oxide can improve the thermal stability and anti-sintering ability of the active metal Ni; (2) the addition of IVA metal oxide improves the dispersion of the active metal Ni, thereby improving the catalyst activity. The modified nickel-based catalyst of this invention effectively improves the catalyst activity and enhances the catalyst's high-temperature stability and anti-sintering ability.

[0009] Preferably, the raw materials for preparing the catalyst, by mass percentage, comprise: 10%~20% NiO, 1%~10% SiO2, 1%~5% Group IVA metal oxides, and 65%~88% Al2O3. In this invention, the content of the active component, nickel oxide, is generally below 30% and above 20%, which increases cost; furthermore, to ensure sufficient catalyst activity, the NiO content must be no less than 10%. Group IVA metal oxides, as co-activating components, should not be too high in content, thus narrowing the preferred range. Excessive SiO2 content can cause carbon deposition on the catalyst.

[0010] Preferably, the crystal phase of Al2O3 is any one or a combination of at least two of γ-Al2O3, δ-Al2O3 and η-Al2O3, with γ-Al2O3 being the most preferred.

[0011] In this invention, the crystal phase depends on the calcination temperature. Calcination temperatures of 300–600°C result in γ-Al₂O₃, while calcination temperatures of 600–900°C result in δ-Al₂O₃ and η-Al₂O₃. γ-Al₂O₃ is preferred because it has a moderate specific surface area, which is beneficial for the dispersion of active components. Furthermore, γ-Al₂O₃ has a moderate specific surface acidity, while δ-Al₂O₃ and η-Al₂O₃ have low surface acidity, which is unfavorable for pyrolysis; their low specific surface area is also unfavorable for the distribution of active components.

[0012] Preferably, the Group IVA metal oxide is any one of tin oxide, germanium oxide, or lead oxide. Tin oxide or lead oxide is preferred in this invention.

[0013] This invention provides a method for preparing the catalyst for catalytic cracking of biomass tar as described above, the method comprising: (1) Alumina raw material, silica raw material, IVA group metal oxide and extrusion aid are kneaded together, then acetic acid aqueous solution is added, kneading is continued, and then the mixture is extruded, dried and calcined to obtain catalyst support; (2) The catalyst support obtained in step (1) is impregnated with sodium carbonate solution, then dried, then sprayed with nickel nitrate solution, washed with hot water, and then dried to obtain the catalyst precursor; (3) The precursor obtained in step (2) is roasted to obtain the catalyst for catalytic cracking of biomass tar.

[0014] Preferably, the mass ratio of the extrusion aid to the alumina raw material in step (1) is 0.04 to 0.08, for example, it can be 0.04, 0.05, 0.06, 0.07 or 0.08, etc.; the extrusion aid is guar gum powder.

[0015] Preferably, in step (1), the mass ratio of silicon dioxide in the silicon dioxide raw material to alumina in the alumina raw material is 0.01~0.16, for example, it can be 0.01, 0.05, 0.08, 0.1, 0.13 or 0.16, etc., and the silicon dioxide raw material is silica sol.

[0016] Preferably, in step (1), the mass ratio of group IVA metal oxide to alumina in the alumina raw material is 0.01 to 0.08, for example, it can be 0.01, 0.02, 0.03, 0.05, 0.07 or 0.08.

[0017] Preferably, the ratio of the amount of acetic acid in the acetic acid aqueous solution to the mass of alumina in the alumina raw material in step (1) is 0.01~0.02, for example, it can be 0.01, 0.02, etc.

[0018] Preferably, the drying temperature in step (1) is 60~150℃, for example, 60℃, 80℃, 100℃, 120℃ or 150℃, and the drying time is 6~12h, for example, 6h, 8h, 10h or 12h. After drying, the catalyst support is obtained by calcination at 300~750℃ for 3~8h.

[0019] Preferably, the soaking time of sodium carbonate solution in step (2) is 3-5 hours, for example, 3 hours, 4 hours or 5 hours, the drying time is 3-6 hours, for example, 3 hours, 4 hours, 5 hours or 6 hours, and the nickel nitrate spraying time is 10-50 minutes, for example, 10 minutes, 20 minutes, 30 minutes, 40 minutes or 50 minutes.

[0020] Preferably, the re-drying temperature in step (2) is 120~180℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, etc., and the drying time is 3~6h, for example, it can be 3h, 4h, 5h or 6h, etc.

[0021] Preferably, the roasting temperature in step (3) is 300~500℃, for example, 300℃, 400℃ or 500℃, and the roasting time is 3~5h, for example, 3h, 4h or 5h.

[0022] Implementing this invention has the following beneficial effects: The catalyst provided by this invention is modified with silica and IVA metal oxide. Silica modifies the alumina support, increasing the acidity of the weakly acidic alumina surface, which is beneficial for the catalytic cracking of tar; in addition, the hydrothermal stability of the silica-modified alumina support is enhanced, giving the catalyst anti-sintering ability. The modification effect of IVA metal oxide is: (1) the interaction between IVA metal oxide and nickel oxide can improve the thermal stability and anti-sintering ability of the active metal Ni; (2) the addition of IVA metal oxide improves the dispersion of the active metal Ni, thereby improving the catalyst activity. The modified nickel-based catalyst of this invention effectively improves the catalyst activity and enhances the catalyst's high-temperature stability and anti-sintering ability.

[0023] The nickel-based catalyst of this invention is a shell catalyst, with the active components uniformly distributed on the surface of an alumina support. Tar in biomass gas undergoes catalytic cracking in the shell to generate small-molecule products. Most of these small-molecule products detach from the catalyst surface in time, while the remaining small portion passes through the catalyst shell into the interior and further catalytically cracks with the silicon-modified alumina to generate small-molecule hydrocarbons. The core-shell structure effectively inhibits catalyst coking and improves the catalyst's resistance to coking. The high activity of this catalyst lowers the tar catalytic cracking reaction temperature, correspondingly reduces the catalyst coking rate, and improves the catalyst's reaction stability.

[0024] The catalyst preparation method provided by this invention is simple, has low raw material cost, good catalytic performance, and high reaction stability, which is conducive to industrial promotion. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a catalyst for the catalytic cracking of biomass tar. The specific composition is: 12.0 wt% NiO, 5.0 wt% SiO2, 3.0 wt% SnO2 and 80.0 wt% Al2O3.

[0028] The preparation process is as follows: 115.6 g of pseudoboehmite powder (containing 80.0 g of alumina), silica sol containing 5.0 g of silica, 3.0 g of tin oxide, and 4.8 g of guar gum powder were mixed evenly and poured into a kneader. Then, an acidic mixed solution (containing 109.7 g of deionized water and 1.4 g of acetic acid) was added all at once. After kneading for 60 min, the mixture was extruded into 2 mm strips using an extruder. After drying at 120℃ for 5 h, it was calcined at 550℃ for 4 h to obtain the catalyst support. The support was impregnated with an equal volume of 5.0 wt% sodium carbonate solution for 4 h, and then dried in an oven at 150.0℃ for 4 h. The dried support was then placed in a vacuum desiccator to cool for later use. The support was then impregnated with an equal volume of a solution containing 46.72 g of nickel nitrate hexahydrate by spraying for 30 min. After impregnation with nickel nitrate, the support was washed 5 times with hot water to remove residual sodium salts. The washed catalyst precursor was then dried in an oven at 150.0℃ for 5 h to remove surface moisture, thus obtaining the catalyst precursor. The dried catalyst precursor was calcined at 400.0℃ for 4 h to obtain a nickel-based shell catalyst.

[0029] Example 2

[0030] This embodiment provides a catalyst for the catalytic cracking of biomass tar. The specific composition is: 15.0 wt% NiO, 7.0 wt% SiO2, 2.0 wt% PbO and 76.0 wt% Al2O3.

[0031] The preparation process is as follows: 109.8 g of boehmite powder (containing 76.0 g of alumina), silica sol containing 7.0 g of silica, 2.0 g of lead oxide, and 4.6 g of guar gum powder were mixed evenly and poured into a kneader. Then, an acidic mixed solution (containing 98.9 g of deionized water and 1.3 g of acetic acid) was added all at once, and kneaded for 70 min. The mixture was then extruded into 2 mm strips using an extruder. After drying at 150.0 °C for 3 h, it was calcined at 600 °C for 4 h to obtain the catalyst support. The support was impregnated with an equal volume of 7.0 wt% sodium carbonate solution for 3 h, and then dried in an oven at 150.0℃ for 5 h. The dried support was then removed and placed in a vacuum desiccator for cooling. The support was then impregnated with an equal volume of 58.4 g nickel nitrate hexahydrate solution by spraying for 40 min. The impregnated support was washed five times with hot water to remove residual sodium salts. The catalyst precursor was then dried in an oven at 150.0℃ for 5 h to remove surface moisture, yielding the catalyst precursor. The dried catalyst precursor was calcined at 400.0℃ for 4 h to obtain a nickel-based shell catalyst.

[0032] Example 3

[0033] This embodiment provides a catalyst for the catalytic cracking of biomass tar. The specific composition is: 18.0 wt% NiO, 6.0 wt% SiO2, 4.0 wt% SnO2 and 72.0 wt% Al2O3.

[0034] 104.1 g of pseudoboehmite powder (containing 72.0 g of alumina), silica sol containing 6.0 g of silica, 4.0 g of tin oxide, and 4.3 g of guar gum powder were mixed evenly and poured into a kneader. Then, an acidic mixed solution (containing 95.3 g of deionized water and 1.3 g of acetic acid) was added all at once, and kneaded for 50 min. The mixture was then extruded into 2 mm strips using an extruder. After drying at 120.0 °C for 5 h, it was calcined at 600 °C for 4 h to obtain the catalyst support. The support was impregnated with an equal volume of 6.0 wt% sodium carbonate solution for 4 h, and then dried in an oven at 150.0℃ for 5 h. The dried support was then removed and placed in a vacuum desiccator for cooling. The support was then impregnated with an equal volume of 70.08 g nickel nitrate hexahydrate solution by spraying for 50 min. After impregnation with nickel nitrate, the support was washed 6 times with hot water to remove residual sodium salts. The washed catalyst precursor was then dried in an oven at 150.0℃ for 5 h to remove surface moisture, thus obtaining the catalyst precursor. The dried catalyst precursor was calcined at 300.0℃ for 5 h to obtain a nickel-based shell catalyst.

[0035] Example 4

[0036] This embodiment provides a catalyst for the catalytic cracking of biomass tar. The specific composition is: 10.0 wt% NiO, 9.0 wt% SiO2, 2.0 wt% PbO and 79.0 wt% Al2O3.

[0037] 114.2 g of pseudoboehmite powder (containing 79.0 g of alumina), silica sol containing 9.0 g of silica, 2.0 g of lead oxide, and 4.7 g of guar gum powder were mixed evenly and poured into a kneader. Then, an acidic mixed solution (containing 98.9 g of deionized water and 1.4 g of acetic acid) was added all at once, and kneaded for 60 min. The mixture was then extruded into 2 mm strips using an extruder. After drying at 150.0 ℃ for 4 h, it was calcined at 700 ℃ for 4 h to obtain the catalyst support. The support was impregnated with an equal volume of 5.0 wt% sodium carbonate solution for 4 h, and then dried in an oven at 150.0 ℃ for 3 h. The dried support was then removed and placed in a vacuum desiccator for cooling. The support was then impregnated with an equal volume of 38.9 g nickel nitrate hexahydrate solution by spraying for 40 min. After impregnation with nickel nitrate, the support was washed 5 times with hot water to remove residual sodium salts. The catalyst precursor was then dried in an oven at 150.0 ℃ for 5 h to remove surface moisture, thus obtaining the catalyst precursor. The dried catalyst precursor was calcined at 350.0 °C for 4 h to obtain a nickel-based shell catalyst.

[0038] Example 5

[0039] This embodiment provides a catalyst for the catalytic cracking of biomass tar. The specific composition is: 20.0 wt% NiO, 2.0 wt% SiO2, 1.0 wt% SnO2 and 77.0 wt% Al2O3.

[0040] 111.3 g of boehmite powder (containing 77.0 g of alumina), silica sol containing 2.0 g of silica, 1.0 g of tin oxide, and 4.62 g of guar gum powder were mixed evenly and poured into a kneader. Then, an acidic mixed solution (containing 112.2 g of deionized water and 1.4 g of acetic acid) was added all at once, and the mixture was kneaded for 80 min. The mixture was then extruded into 2 mm strips using an extruder. After drying at 150.0 °C for 4 h, it was calcined at 600 °C for 4 h to obtain the catalyst support.

[0041] The support was impregnated with an equal volume of 8.0 wt% sodium carbonate solution for 4 h, and then dried in an oven at 150.0 ℃ for 3 h. The dried support was then removed and placed in a vacuum desiccator for cooling. The support was then impregnated with an equal volume of a solution containing 77.9 g of nickel nitrate hexahydrate by spraying for 40 min. After impregnation with nickel nitrate, the support was washed 6 times with hot water to remove residual sodium salts. The catalyst precursor was then dried in an oven at 150.0 ℃ for 6 h to remove surface moisture, thus obtaining the catalyst precursor. The dried catalyst precursor was calcined at 500.0 °C for 4 h to obtain a nickel-based shell catalyst.

[0042] Example 6

[0043] The difference between this embodiment and Embodiment 4 is that the specific composition of this embodiment is: 5 wt% NiO, 12 wt% SiO2, 7.0 wt% PbO, and 76.0 wt% Al2O3. The preparation process is the same as in Embodiment 4.

[0044] Example 7

[0045] The difference between this embodiment and Embodiment 4 is that the specific composition of this embodiment is: 25 wt% NiO, 15 wt% SiO2, 10.0 wt% PbO and 55.0 wt% Al2O3. The preparation process is the same as in Embodiment 4.

[0046] Example 8

[0047] The difference between this embodiment and embodiment 4 is that PbO is replaced with GeO2, while the rest are the same as in embodiment 4.

[0048] Comparative Example 1 Referring to the catalyst preparation process in Example 4, the difference is that no modifying substances are added during the support preparation process, resulting in an unmodified catalyst support. The catalyst prepared in the comparative example has the following composition: 10.0 wt% NiO and 90.0 wt% Al2O3.

[0049] Comparative Example 2 Referring to the catalyst preparation process in Example 4, the difference is that no silicon oxide is added during the support preparation process, resulting in a catalyst support modified with group IVA metal oxides. The catalyst prepared in Comparative Example 2 has the following composition: 10.0 wt% NiO, 2.0 wt% PbO, and 88.0 wt% Al2O3.

[0050] Comparative Example 3 Referring to the catalyst preparation process in Example 1, the difference is that no Group IVA metal oxides are added during the support preparation process, resulting in a silicon-modified catalyst support. The catalyst prepared in Comparative Example 2 has the following composition: 10.0 wt% NiO, 9.0 wt% SiO2, and 81.0 wt% Al2O3.

[0051] Comparative Example 4: A catalyst with NiO loading of 10.0 wt%, La2O3 loading of 8.0 wt%, CeO2 loading of 5.4 wt%, and MgO loading of 1.8 wt% was prepared according to the preparation steps of Example 4 of CN101693204B.

[0052] The catalytic performance of the catalysts provided in Examples 1-8 and Comparative Examples 1-4 was evaluated. Specifically, toluene was used as a biomass tar model compound to evaluate the catalysts of this invention. The experimental conditions were as follows: catalyst reduction temperature: 500.0~800.0℃, reaction temperature: 600.0~800.0℃, space velocity: 1~3h⁻¹. -1 The composition of the experimental raw gas was: water vapor 19.0%, N2 0.0%, C7H8 1.0%. The catalyst needed to be reduced in a hydrogen atmosphere for 6 hours before use. The results are shown in Table 1 below.

[0053] Table 1 catalyst Reduction temperature (°C) Reaction temperature (°C) <![CDATA[Heavy space velocity (h -1 )]]> Toluene conversion rate (%) Example 1 550.0 650.0 1.5 93.4 Example 2 550.0 700.0 1.5 96.1 Example 3 600.0 700.0 2.0 99.5 Example 4 600.0 600.0 2.0 92.3 Example 5 700.0 650.0 1.5 95.2 Example 6 600.0 600.0 2.0 91.5 Example 7 600.0 600.0 2.0 98.0 Example 8 600.0 600.0 2.0 91.8 Comparative Example 1 600.0 600.0 2.0 85.2 Comparative Example 2 600.0 600.0 2.0 88.6 Comparative Example 3 600.0 600.0 2.0 88.3 Comparative Example 4 600.0 600.0 2.0 90.6 As can be seen from Table 1, the hourly space velocity is 2.0 h. -1The reaction temperature was 700.0℃. The catalyst in Example 3 exhibited extremely high activity, with almost complete conversion of toluene. Compared to Comparative Example 1, the catalyst in Example 4 showed a higher toluene conversion rate, indicating that modified nickel-based catalysts can improve catalyst activity. Compared to Comparative Example 1, the catalyst modified with IVA metal oxide in Comparative Example 2 showed a certain improvement in activity. The addition of IVA metal oxide can make the active component Ni more uniformly distributed, improving the dispersion of the active component. Furthermore, the activity data of the catalyst in Comparative Example 3 shows that silicon modification helps to improve catalyst activity. Since the addition of silicon not only enhances the acidity of the catalyst surface but also improves the pore structure and thermal stability of the catalyst, the addition of silicon to the unmodified nickel-based catalyst formulation further improves the catalyst activity and thermal stability. As shown in Example 4, silicon and IVA metal oxide modification can enhance the acidity of the catalyst surface, improve the distribution of the active component, and further improve the thermal stability and anti-carbon deposition ability of the catalyst. The catalysts in Examples 1-5 are all core-shell structure catalysts, with modified alumina as the core and nickel oxide as the active component as the shell. In biomass gas, tar undergoes catalytic cracking in the shell layer to generate small molecule products. Most of these small molecule products can detach from the catalyst surface in time, while the remaining small molecule products enter the interior through the catalyst shell layer and undergo further catalytic cracking with silicon-modified alumina to generate small molecule hydrocarbons. The core-shell structure effectively inhibits the formation of carbon deposits on the catalyst and improves the catalyst's resistance to carbon deposition.

[0054] In Comparative Example 4, the catalyst with NiO loading of 10.0 wt%, La2O3 loading of 8.0 wt%, CeO2 loading of 5.4 wt%, and MgO loading of 1.8 wt% achieved a toluene conversion rate of only 90.6%, which is less active than the silicon-IVA metal oxide modified catalyst in Example 4.

[0055] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst for the catalytic cracking of biomass tar, characterized in that, The raw materials for preparing the catalyst include, by mass percentage: 5%~30% NiO, 0.05%~15% SiO2, 0.05%~10% Group IVA metal oxides, and 45%~94.9% Al2O3.

2. The catalyst according to claim 1, characterized in that, The raw materials for preparing the catalyst include, by mass percentage: 10%~20% NiO, 1%~10% SiO2, 1%~5% Group IVA metal oxides, and 65%~88% Al2O3.

3. The catalyst according to claim 1 or 2, characterized in that, The crystal phase of Al2O3 is any one or a combination of at least two of γ-Al2O3, δ-Al2O3 and η-Al2O3, preferably γ-Al2O3; Preferably, the IVA group metal oxide is any one of tin oxide, germanium oxide, or lead oxide.

4. The method for preparing the catalyst for catalytic cracking of biomass tar according to claim 1 or 2, characterized in that, The preparation method includes: (1) Alumina raw material, silica raw material, IVA group metal oxide and extrusion aid are kneaded together, then acetic acid aqueous solution is added, kneading is continued, then extruded and calcined to obtain catalyst support; (2) The catalyst support obtained in step (1) is impregnated with sodium carbonate solution, then dried, then sprayed with nickel nitrate solution, washed with hot water, and then dried to obtain the catalyst precursor; (3) The precursor obtained in step (2) is roasted to obtain the catalyst for catalytic cracking of biomass tar.

5. The preparation method according to claim 4, characterized in that, The mass ratio of the extrusion aid to the alumina raw material in step (1) is 0.04~0.08; the extrusion aid is guar gum powder.

6. The preparation method according to claim 4, characterized in that, In step (1), the mass ratio of silicon dioxide in the silicon dioxide raw material to aluminum oxide in the aluminum oxide raw material is 0.01~0.16, and the silicon dioxide raw material is silica sol.

7. The preparation method according to claim 4, characterized in that, In step (1), the mass ratio of IVA group metal oxide to alumina in the alumina raw material is 0.01~0.

08.

8. The preparation method according to claim 4, characterized in that, The mass ratio of acetic acid in the acetic acid aqueous solution to the mass of alumina in the alumina raw material in step (1) is 0.01~0.

02.

9. The preparation method according to claim 4, characterized in that, The drying temperature in step (1) is 60~150℃ and the drying time is 6~12h; after drying, the catalyst support is obtained by calcination at 300~750℃ for 3~8h.

10. The preparation method according to claim 4, characterized in that, The sodium carbonate solution immersion time in step (2) is 3-5 hours, the drying time is 3-6 hours, and the nickel nitrate spraying time is 10-50 minutes. Preferably, the re-drying temperature in step (2) is 120~180℃, and the re-drying time is 3~6h; Preferably, the roasting temperature in step (3) is 300~500℃ and the roasting time is 3~5h.