A method for preparing a hydrotalcite-derived hollow catalyst and its application in CO2 tar reforming

Abstract

The application relates to a water-sliding-hill derived hollow catalyst preparation method and CO2 tar reforming application; glucose and an aqueous solution are configured, centrifugation and drying are carried out to obtain carbon sphere powder; a mixed nitrate solution of nickel nitrate hexahydrate, cobalt nitrate hexahydrate and aluminum nitrate nonahydrate is configured; an alkali solution is configured; a sodium carbonate precipitant solution is configured; the carbon sphere solid powder is dispersed in the aqueous solution and is ultrasonically treated; the mixed nitrate solution, the precipitant solution and the alkali solution are added into the ultrasonically treated solution, the alkali solution controls the pH value to be 9.5-10.5, and a layered double hydroxide is obtained through aging, centrifugation, drying and calcination; the double hydroxide is reduced by hydrogen to obtain a catalyst. The catalyst is applied to a tar and CO2 reforming reaction; the conversion rate is 75.88% for C7H8 and 74.04% for CO2; the selectivity is 85.44% for H2 and 86.58% for CO; the performance of the catalyst is stable, and there is no deactivation phenomenon.

Description

Technical Field

[0001] This invention relates to the preparation and application of a hydrotalcite-derived nickel-cobalt catalyst, a method for preparing a hydrotalcite-derived hollow catalyst, and its application in CO2 tar reforming. Specifically, it relates to the preparation method of a hollow-structure hydrotalcite-derived nickel-cobalt alloy catalyst and its application in tar and CO2 reforming reactions. Background Technology

[0002] With the escalating crisis of fossil fuel reserves and the worsening of environmental pollution, the utilization of renewable energy has received widespread attention. Biomass, as a clean and renewable energy source, is currently the world's fourth largest energy source after coal, oil, and natural gas. It has advantages such as low carbon emissions, recyclability, huge reserves, and ease of storage, and holds promise for solving the fossil fuel crisis.

[0003] Currently, gasification technology is an effective way to realize the high-value utilization of biomass, converting biomass into syngas rich in H2 and CO. However, tar byproducts are inevitably generated during biomass gasification. Tar production not only reduces the overall energy efficiency of the gasification system, causes pollution and blockage of downstream equipment and pipelines, and affects the safe and stable operation of the system, but also seriously limits the development of biomass gasification technology. Tar contains a large amount of polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic and have environmental impacts. Therefore, tar removal is crucial for biomass gasification technology. Toluene is one of the main compounds in biomass tar. Currently, various methods have been researched and tested to eliminate tar produced by biomass gasification. Physical tar removal methods mainly include water washing, filtration, and electrostatic precipitators, the principle of which is to physically separate tar from the product gas. Water washing and filtration processes are simple, relatively easy to establish, and have low technical requirements. However, industrial applications are increasingly reluctant to use water washing to remove tar because treating wastewater from scrubbers is challenging and costly; using filtration devices (such as sand beds, fabric filters, ceramic filters, etc.) inevitably increases system pressure and interferes with normal operation; and electrostatic precipitators are expensive and inconvenient to operate. In contrast, chemical tar removal methods are the preferred approach and have broad application prospects. Thermal cracking can effectively decompose tar compounds into permanent gases and solid dust, but it requires increased temperature or oxygen injection. Therefore, thermocatalytic reforming appears to be the most effective and economical means of eliminating tar. Catalytic tar reforming can convert tar into syngas rich in H2 and CO through catalysts, while increasing the gas's calorific value, thereby improving the efficiency of gasification technology. Furthermore, in addition to tar, the presence of a large amount of CO2 during gasification significantly reduces the calorific value of the syngas, thus affecting its quality. Depending on the gasification conditions and biomass type, the CO2 content in the gas produced during biomass gasification ranges from 10-30 vol%. Therefore, using CO2 as the atmosphere for tar reforming can simultaneously convert tar, avoiding the introduction of other gasifying agents and generating additional energy consumption, making it an effective and clean technology.

[0004] Catalyst selection is crucial for developing efficient catalytic tar reforming systems. Over the past few decades, numerous catalysts have been used in tar reforming reactions. Tar reforming catalysts can be broadly categorized into natural minerals and synthetic materials. Natural minerals, such as dolomite and olivine, are inexpensive and widely available, but they exhibit poor reactivity, severe carbon deposition, and poor stability. Most synthetic catalysts include non-precious metals (Fe, Ni, Co, etc.) or precious metals (such as Pt, Rh, Pd, etc.). Precious metals possess good catalytic activity and resistance to carbon deposition, but their high cost, especially for large-scale production, limits their industrial applications. Nickel-based catalysts among non-precious metals are inexpensive and exhibit strong reactivity in the cleavage of C, C, CH, and OH bonds, leading to extensive research on their application in tar removal processes. However, a major drawback of conventional supported nickel-based catalysts is their susceptibility to deactivation, thus shortening their lifespan. The primary causes of deactivation are carbon deposition and metal sintering at high temperatures. Carbon deposition on catalysts can encapsulate active metal particles, preventing reactants from entering the metal. Sintering, on the other hand, can lead to metal particle agglomeration, reducing the available surface area of ​​active metal and thus decreasing catalyst activity. Therefore, developing efficient, carbon-resistant, and highly stable nickel-based catalysts is a crucial issue that urgently needs to be addressed to achieve the industrialization of tar CO2 reforming. Summary of the Invention

[0005] Currently, to improve the quality of gasification technology, most research focuses on steam reforming of tar, with few reports on using CO2 as a reforming agent. This invention reforms CO2 byproducts and tar byproducts, avoiding the introduction of other gasifying agents and the resulting additional energy consumption.

[0006] Existing nickel-based catalysts for tar reforming are inexpensive, but they are prone to metal sintering and carbon deposition. There is an urgent need to improve the performance of nickel-based tar conversion catalysts, primarily in terms of catalyst stability and activity.

[0007] This invention provides a method for preparing a non-precious metal alloy encapsulated in a hollow structure derived from hydrotalcite. The outer shell acts as a protective barrier for the metal nanoparticles, effectively preventing metal sintering and agglomeration. The porous shell structure promotes the reaction between gaseous reactants and the core active components. The cavity promotes reactant enrichment, increases reactant concentration, and accelerates the rapid conversion of carbon intermediates, exhibiting anti-carbon deposition properties. Furthermore, the cavity structure can inhibit carbon deposition growth. Therefore, nickel catalysts with hollow structures can be considered as feasible catalysts for tar conversion.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing a hydrotalcite-derived hollow catalyst includes the following steps:

[0010] (1) Mix glucose and aqueous solution, heat in a hydrothermal reactor, and obtain carbon ball powder by centrifugation and drying.

[0011] (2) Add nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and aluminum nitrate nonahydrate to deionized water to obtain a mixed nitrate solution;

[0012] (3) Dissolve sodium hydroxide in deionized water to obtain an alkaline solution;

[0013] (4) Dissolve sodium carbonate in deionized water to obtain a precipitant solution;

[0014] (5) Disperse the carbon ball solid powder obtained in step (1) in an aqueous solution and sonicate for 10-30 min;

[0015] (6) The nitrate mixture, precipitant solution and alkaline solution are added dropwise to step (5) at the same time. The pH of the reaction solution is controlled to be 9.5-10.5 by sodium hydroxide solution. Stirring is continued during the dropwise addition until the metal precursor is completely added. Then, the stirring is stopped. After aging, centrifugation, drying and calcination, layered double hydroxide is obtained.

[0016] (7) The layered double hydroxide obtained in step (6) is reduced with hydrogen to obtain a catalyst.

[0017] In step (1), the glucose concentration is 160-190 g / L, the hydrothermal temperature is 175℃-185℃, and the hydrothermal time is 8-11 h; the centrifugal washing speed is 4000-6000 rpm, the drying temperature is 50-70℃, and the drying time is 20-25 h.

[0018] In step (2), the concentration of nickel nitrate hexahydrate is 85.5-89 g / L; the mass ratio of cobalt nitrate hexahydrate to water is 43.1-44.4 g / L; and the mass ratio of aluminum nitrate nonahydrate to water is 55.5-57 g / L.

[0019] The concentration of the sodium hydroxide solution in step (3) is 1.7-2.3 mol / L.

[0020] In step (4), the concentration of the sodium carbonate precipitant solution is 0.7-1.3 mol / L, or 74.2-137.8 g / L.

[0021] In step (5), the concentration of carbon ball solid powder dispersed in water is 17-25 g / L.

[0022] The mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate, and carbon spheres in step (6) is 85.5-89:43.1-44.4:55.5-57:74.2-137.8:17-25.

[0023] In step (6), the titration temperature is 55-65℃, the stirring speed is 450-650rpm, the aging temperature is 55-65℃, the aging time is 15-19h, the washing speed is 5000-7000rpm, the drying temperature is 70-90℃, and the drying time is 20-25h. The calcination step is carried out in an air atmosphere, the calcination temperature is 490-520℃, the calcination time is 3.7-5h, and the calcination rate is 5-10℃ / min, to obtain layered double hydroxides.

[0024] In step (7), the layered double hydroxide is reduced in a hydrogen atmosphere at a temperature of 680-720℃, a reduction heating rate of 8-12℃ / min, and a reduction time of 0.9-1.5h, finally yielding the catalyst.

[0025] The hydrotalcite-derived hollow catalyst prepared by the method of this invention is applied to the tar and CO2 reforming reaction. Toluene feed gas and CO2 gas are passed into a furnace containing the catalyst, and the catalytic reforming reaction is carried out in the presence of the catalyst. The conversion rate of C7H8 (tar model compound) reaches 75.88%, the CO2 conversion rate reaches 74.04%, the H2 selectivity reaches 85.44%, and the CO selectivity reaches 86.58%. Furthermore, the catalyst performance remains stable after 700 min of reaction, without any deactivation.

[0026] The following process conditions can be used for specific applications:

[0027] (1) C7H8 was used as a model tar compound and was injected into the reaction system at a rate of 5.08 μL / min using an injection pump.

[0028] (2) The syringe pump is LSPO1-1A, Longer Pump, Baoding, China.

[0029] (3) The amount of catalyst used is 0.05g.

[0030] (4) The reforming reaction temperature is 700℃ and the CO2 flow rate is 7.5mL / min.

[0031] (5) The carrier gas is N2, and the flow rate is 41.4 mL / min.

[0032] The advantages and superior effects of this invention are as follows:

[0033] (1) This invention provides a method for preparing syngas (H2 and CO) by catalytic reforming of carbon dioxide and toluene. Using CO2 as the atmosphere for tar reforming can simultaneously convert tar, avoiding the introduction of other gasifying agents and generating additional energy consumption, which is an effective and clean technology.

[0034] (2) The precipitate formed during the preparation of the catalyst is a layered double hydroxide after washing and drying. The layered double hydroxide can make the active metal cations uniformly mixed at the atomic level, and produce highly stable and dispersed metals during calcination and reduction. In the subsequent calcination stage, there can be a strong interaction between the metal and the support, which helps to accelerate the reaction process.

[0035] (3) Hydrotalcite-derived catalysts exhibit excellent catalytic activity and stability in the thermocatalytic toluene and CO2 reforming reactions. The cavity promotes reactant enrichment, increases reactant concentration, accelerates the rapid conversion of carbon intermediates, and exhibits resistance to carbon deposition. Furthermore, the cavity structure can inhibit carbon deposition. In addition, non-precious metal catalysts are inexpensive and hold promise for industrial-scale applications. Attached Figure Description

[0036] Figure 1 TEM image of the catalyst prepared in Example 1

[0037] Figure 2 : Reactivity test diagram of the catalyst prepared in Example 1

[0038] Figure 3 : Reactivity test graph of the catalyst prepared in Example 2

[0039] Figure 4 : Reactivity test graph of the catalyst prepared in Example 3

[0040] Figure 5 : Reactivity test graph of the catalyst prepared in Example 4

[0041] Figure 6 : Reactivity test diagram of the catalyst prepared in Example 5 Detailed Implementation

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention.

[0043] Example 1

[0044] (1) 18g of glucose was dissolved in 100mL of deionized water to prepare a 180g / L solution, which was then transferred to a polytetrafluoroethylene liner and hydrothermally heated at 180℃ for 10h. The precipitate was washed with deionized water at 4000rpm and dried at 60℃ for 20h to obtain carbon spheres.

[0045] (2) 8.72g of Ni(NO3)2·6H2O, 4.36g of Co(NO3)·6H2O, and 5.63g of Al(NO)3·9H2O were dissolved in 100mL of deionized water and stirred evenly to obtain a nitrate mixture.

[0046] (3) Disperse 2g of carbon balls in 100mL of water, sonicate for 10min, and prepare a 20g / L solution.

[0047] (4) Dissolve 10.6g of sodium carbonate in 100mL of water to prepare a 1mol / L sodium carbonate solution.

[0048] (5) Dissolve 8g of sodium hydroxide in 100mL of water to prepare a 2mol / L sodium hydroxide solution.

[0049] (6) The nitrate mixture, 1 mol / L sodium carbonate solution and 2 mol / L sodium hydroxide solution are simultaneously added dropwise to the aqueous solution in step (3) (the mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and carbon balls is 8.72:4.36:5.63:10.6:2), and magnetic stirring is performed. The reaction temperature is 60℃, the magnetic stirring speed is 500 rpm, and the pH value of the reaction solution is controlled to be 10 by controlling the sodium hydroxide solution. After the nitrate mixture was added dropwise, stirring was stopped, and the mixture was allowed to stand at 60°C for 18 hours. The aged precipitate was washed with deionized water at 6000 rpm until neutral. The washed precipitate was dried at 80°C for 24 hours, and then calcined in a muffle furnace at 500°C for 4 hours in an air atmosphere at 10°C / min. The calcined product was then reduced from room temperature to 700°C for 1 hour in a hydrogen atmosphere at a heating rate of 10°C / min to obtain the catalyst.

[0050] The catalyst obtained in this embodiment shows, as can be seen from the TEM transmission image, that an internal cavity is formed, resulting in a hollow structure. Figure 1 The catalyst achieved a conversion rate of 75.88% for C7H8 (a tar model compound), a CO2 conversion rate of 74.04%, a H2 selectivity of 85.44%, and a CO selectivity of 86.58%. Furthermore, the catalyst's performance remained stable after 700 min of reaction, showing no signs of deactivation. Figure 2 ).

[0051] Example 2

[0052] (1) 16g of glucose was dissolved in 100mL of deionized water to prepare a 160g / L solution, which was then transferred to a polytetrafluoroethylene liner and hydrothermally heated at 175℃ for 9h. The precipitate was washed with deionized water at 5000rpm and dried at 55℃ for 22h to obtain carbon spheres.

[0053] (2) 8.90g of Ni(NO3)2·6H2O, 4.37g of Co(NO3)·6H2O, and 5.63g of Al(NO)3·9H2O were dissolved in 100mL of deionized water and stirred evenly to obtain a nitrate mixture.

[0054] (3) Disperse 2.5g of carbon balls into 100mL of water, sonicate for 20min, and prepare a 25g / L solution.

[0055] (4) Dissolve 7.42g of sodium carbonate in 100mL of water to prepare a 0.7mol / L sodium carbonate solution.

[0056] (5) Dissolve 8g of sodium hydroxide in 100mL of water to prepare a 2mol / L sodium carbonate solution.

[0057] (6) The nitrate mixture, 0.7 mol / L sodium carbonate solution and 2 mol / L sodium hydroxide solution were simultaneously added dropwise to the aqueous solution in step (3) (the mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and carbon balls was 8.9:4.37:5.63:7.42:2.5), and magnetic stirring was performed. The reaction temperature was 55℃, the magnetic stirring speed was 450 rpm, and the pH of the reaction solution was controlled to be 10.5 by controlling the amount of sodium hydroxide solution added. After the nitrate mixture was added dropwise, stirring was stopped, and the mixture was allowed to stand at 60°C for 15 hours. The aged precipitate was washed with deionized water at 5000 rpm until neutral. The washed precipitate was dried at 80°C for 24 hours, and then calcined in a muffle furnace at 500°C for 4 hours in an air atmosphere at 8°C / min. The calcined product was then reduced from room temperature to 700°C for 1.2 hours in a hydrogen atmosphere at a heating rate of 10°C / min to obtain the catalyst.

[0058] In this embodiment, the catalyst achieved a conversion rate of 80.16% for C7H8 (the tar model compound), a CO2 conversion rate of 76.67%, a H2 selectivity of 85.56%, and a CO selectivity of 84.30%. Furthermore, the catalyst's performance remained stable after 700 min of reaction, showing no signs of deactivation. Figure 3 )

[0059] Example 3

[0060] (1) 19g of glucose was dissolved in 100mL of deionized water to prepare a 190g / L solution, which was then transferred to a polytetrafluoroethylene liner and hydrothermally heated at 180℃ for 10h. The precipitate was washed with deionized water at 4500rpm and dried at 50℃ for 25h to obtain carbon spheres.

[0061] (2) 8.55g of Ni(NO3)2·6H2O, 4.37g of Co(NO3)·6H2O, and 5.63g of Al(NO)3·9H2O were dissolved in 100mL of deionized water and stirred evenly to obtain a nitrate mixture.

[0062] (3) Disperse 1.7g of carbon balls into 100mL of water and sonicate for 15min to prepare a 17g / L solution.

[0063] (4) Dissolve 13.78g of sodium carbonate in 100mL of water to prepare a 1.3mol / L sodium carbonate solution.

[0064] (5) Dissolve 8g of sodium hydroxide in 100mL of water to prepare a 2mol / L sodium carbonate solution.

[0065] (6) The nitrate mixture, 1.3 mol / L sodium carbonate solution and 2 mol / L sodium hydroxide solution were simultaneously added dropwise to the aqueous solution in step (3) (the mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and carbon balls was 8.55:4.37:5.63:13.78:1.7), and magnetic stirring was performed. The reaction temperature was 65℃, the magnetic stirring speed was 650 rpm, and the pH value of the reaction solution was controlled to be 10.3 by controlling the amount of sodium hydroxide solution added. After the nitrate mixture was added dropwise, stirring was stopped, and the mixture was allowed to stand at 55°C for 19 hours. The aged precipitate was washed with deionized water at 7000 rpm until neutral. The washed precipitate was dried at 70°C for 25 hours, and then calcined in a muffle furnace at 520°C for 3.7 hours in an air atmosphere at 10°C / min. The calcined product was then reduced from room temperature to 720°C for 0.9 hours in a hydrogen atmosphere at a heating rate of 12°C / min to obtain the catalyst.

[0066] In this embodiment, the catalyst achieved a conversion rate of 66.73% for C7H8 (the tar model compound), a CO2 conversion rate of 67.66%, a H2 selectivity of 78.88%, and a CO selectivity of 85.07%. Furthermore, the catalyst's performance remained stable after 700 min of reaction, showing no signs of deactivation. Figure 4 )

[0067] Example 4

[0068] (1) 17g of glucose was dissolved in 100mL of deionized water to prepare a 170g / L solution, which was then transferred to a polytetrafluoroethylene liner and hydrothermally heated at 185℃ for 8h. The precipitate was washed with deionized water at 5500rpm and dried at 65℃ for 21h to obtain carbon spheres.

[0069] (2) 8.67g of Ni(NO3)2·6H2O, 4.44g of Co(NO3)·6H2O, and 5.70g of Al(NO)3·9H2O were dissolved in 100mL of deionized water and stirred evenly to obtain a nitrate mixture.

[0070] (3) Disperse 2.3g of carbon spheres into 100mL of water and sonicate for 30min to prepare a 23g / L solution.

[0071] (4) Dissolve 10.60g of sodium carbonate in 100mL of water to prepare a 1mol / L sodium carbonate solution.

[0072] (5) Dissolve 6.8g of sodium hydroxide in 100mL of water to prepare a 1.7mol / L sodium carbonate solution.

[0073] (7) The nitrate mixture, 1 mol / L sodium carbonate solution and 1.7 mol / L sodium hydroxide solution were simultaneously added dropwise to the aqueous solution in step (3) (the mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and carbon balls was 8.67:4.44:5.70:10.60:2.3), and magnetic stirring was performed. The reaction temperature was 60℃ and the magnetic stirring speed was 550 rpm. The pH value of the reaction solution was controlled to be 9.5 by controlling the amount of sodium hydroxide solution added. After the nitrate mixture was added dropwise, stirring was stopped, and the mixture was allowed to stand at 65°C for 16 hours. The aged precipitate was washed with deionized water at 6000 rpm until neutral. The washed precipitate was dried at 90°C for 20 hours, and then calcined in a muffle furnace at 490°C for 5 hours in an air atmosphere at 10°C / min. The calcined product was then reduced from room temperature to 700°C for 1 hour in a hydrogen atmosphere at a heating rate of 10°C / min to obtain the catalyst.

[0074] In this embodiment, the catalyst achieved a conversion rate of 75.56% for C7H8 (the tar model compound), a CO2 conversion rate of 68.35%, a H2 selectivity of 77.17%, and a CO selectivity of 78.54%. Furthermore, the catalyst's performance remained stable after 700 min of reaction, showing no signs of deactivation. Figure 5 )

[0075] Example 5

[0076] (1) 17.5 g of glucose was dissolved in 100 mL of deionized water to prepare a 175 g / L solution, which was then transferred to a polytetrafluoroethylene liner and hydrothermally heated at 178 °C for 11 h. The precipitate was washed with deionized water at 6000 rpm and dried at 70 °C for 20 h to obtain carbon spheres.

[0077] (2) 8.61g of Ni(NO3)2·6H2O, 4.31g of Co(NO3)·6H2O, and 5.55g of Al(NO)3·9H2O were dissolved in 100mL of deionized water and stirred evenly to obtain a nitrate mixture.

[0078] (3) Disperse 2g of carbon balls in 100mL of water and sonicate for 20min to prepare a 20g / L solution.

[0079] (4) Dissolve 10.6g of sodium carbonate in 100mL of water to prepare a 1mol / L sodium carbonate solution.

[0080] (5) Dissolve 9.2g of sodium hydroxide in 100mL of water to prepare a 2.3mol / L sodium carbonate solution.

[0081] (6) The nitrate mixture, 1 mol / L sodium carbonate solution and 2.3 mol / L sodium hydroxide solution were simultaneously added dropwise to the aqueous solution in step (3) (the mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and carbon balls was 8.61:4.31:5.55:10.60:2), and magnetic stirring was performed. The reaction temperature was 55℃ and the magnetic stirring speed was 550 rpm. The pH value of the reaction solution was controlled to 10 by controlling the amount of sodium hydroxide solution added. After the nitrate mixture was added dropwise, stirring was stopped, and the mixture was allowed to stand at 60°C for 18 hours. The aged precipitate was washed with deionized water at 6000 rpm until neutral. The washed precipitate was dried at 80°C for 24 hours, and then calcined in a muffle furnace at 500°C for 4 hours in an air atmosphere at a rate of 5°C / min. The calcined product was then reduced from room temperature to 680°C for 1.5 hours in a hydrogen atmosphere at a heating rate of 8°C / min to obtain the catalyst.

[0082] In this embodiment, the catalyst achieved a conversion rate of 60.35% for C7H8 (the tar model compound), a CO2 conversion rate of 62.91%, a H2 selectivity of 70.45%, and a CO selectivity of 73.82%. Furthermore, the catalyst's performance remained stable after 700 min of reaction, showing no signs of deactivation. Figure 6 )

[0083] test:

[0084] The catalyst prepared by the method in the above examples was used in the tar and CO2 reforming reaction, and the test method is as follows:

[0085] 0.05 g of catalyst was weighed and placed in the middle of a quartz tube (600 mm long, 25 mm in diameter) supported by 0.03 g of quartz wool (80-100 mesh). The quartz tube was then placed in the heating zone of a vertical furnace. The CO2 flow rate was 7.5 mL / min and the N2 flow rate was 41.4 mL / min. C7H8, as a model tar compound, was injected into the reaction system via a syringe pump at a rate of 5.08 μL / min. After being vaporized by the heating device (approximately 1.08 mL / min as a gaseous component), it entered the reactor along with a mixture of CO2 and N2 (total flow rate 50 mL / min). The molar ratio of C7H8 to CO2 was 1:7.

[0086] The products were determined by online gas chromatography. The product analysis system was an online gas chromatograph (GC, 7890A, Agilent Technologies, USA) equipped with a Carboxen 1000 packed column and a DB-5 capillary column. The packed column inlet temperature was maintained at 250°C, the column temperature at 80°C, and the capillary column inlet temperature at 300°C. Small molecule gaseous products, including H2, CO, and CO2, were analyzed using a Carboxen 1000 packed column and a TCD detector, while light hydrocarbons (LHC) and toluene were measured using a DB-5 capillary column and a flame ionization detector (FID). The test results are shown in Figure 1.

[0087] Example <![CDATA[Conversion rate of C7H8(%)]]> <![CDATA[CO2 conversion rate (%)]]> <![CDATA[H2 Selectivity (%)]]> CO selectivity (%) 1 75.88 74.04 85.44 86.58 2 80.16 76.67 85.56 84.30 3 66.73 67.66 78.88 85.07 4 75.56 68.35 77.17 78.54 5 60.35 62.91 70.45 73.82

[0088] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. The application of a hydrotalcite-derived hollow catalyst in the tar and CO2 reforming reaction, characterized in that, The hydrotalcite-derived hollow catalyst was prepared by the following method: (1) Mix glucose and aqueous solution, heat in a hydrothermal reactor, and obtain carbon ball powder by centrifugation and drying. (2) Add nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and aluminum nitrate nonahydrate to deionized water to obtain a mixed nitrate solution; (3) Dissolve sodium hydroxide in deionized water to obtain an alkaline solution; (4) Dissolve sodium carbonate in deionized water to obtain a precipitant solution; (5) Disperse the carbon ball solid powder obtained in step (1) in an aqueous solution and sonicate for 10-30 min; (6) Add the nitrate mixed solution, precipitant solution and alkaline solution dropwise to (5) at the same time. Control the pH of the reaction solution to 9.5-10.5 by sodium hydroxide solution. Stir continuously during the dropwise addition until the metal precursor solution is completely added. Stop stirring and obtain the metal oxide after aging, centrifugation, drying and calcination. (7) The metal oxide obtained in step (6) is reduced with hydrogen to obtain a catalyst; Toluene, used as a feedstock for the tar model compound, and CO2 gas are introduced into a furnace containing the catalyst to carry out a catalytic reforming reaction in the presence of the catalyst.

2. The application as described in claim 1, characterized in that, In step (1), the glucose concentration is 160-190 g / L, the hydrothermal temperature is 175 ℃-185 ℃, and the hydrothermal time is 8-11 h; the centrifugal washing speed is 4000-6000 rpm, the drying temperature is 50-70 ℃, and the drying time is 20-25 h.

3. The application as described in claim 1, characterized in that, In step (2), the concentration of nickel nitrate hexahydrate is 85.5-89 g / L; the mass ratio of cobalt nitrate hexahydrate to water is 43.1-44.4 g / L; and the mass ratio of aluminum nitrate nonahydrate to water is 55.5-57 g / L.

4. The application as described in claim 1, characterized in that, The concentration of sodium hydroxide solution in step (3) is 68-92 g / L.

5. The application as described in claim 1, characterized in that, The concentration of the sodium carbonate precipitant solution in step (4) is 74.2-137.8 g / L.

6. The application as described in claim 1, characterized in that, In step (5), the concentration of carbon ball solid powder dispersed in water is 17-25 g / L.

7. The application as described in claim 1, characterized in that, The mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate, and carbon spheres in step (6) is 85.5-89:43.1-44.4:55.5-57:74.2-137.8:17-25.

8. The application as described in claim 1, characterized in that, In step (6), the dropping temperature is 55-65 ℃, the stirring speed is 450-650 rpm, the aging temperature is 55-65 ℃, the aging time is 15-19 h, the centrifugation speed is 5000-7000 rpm, the drying temperature is 70-90 ℃, and the drying time is 20-25 h. The calcination step is carried out in an air atmosphere, the calcination temperature is 490-520 ℃, the calcination time is 3.7-5 h, and the calcination rate is 5-10 ℃ / min.

9. The application as described in claim 8, characterized in that, In step (7), the metal oxide is reduced in a hydrogen atmosphere at a temperature of 680-720 °C, a heating rate of 8-12 °C / min, and a reduction time of 0.9-1.5 h.

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