Biomass gasification tar-based porous carbon spheres and preparation method and application thereof

Abstract

The application discloses a biomass gasification tar-based porous carbon ball and a preparation method and application thereof, and belongs to the technical field of carbon materials. In order to realize high-value resource utilization of gasification tar and preparation of micro-mesoporous adjustable multi-level porous carbon material, the application provides a preparation method of a biomass gasification tar-based porous carbon ball, which comprises the following steps: mixing tar, gasification slag, polyacrylonitrile and an organic solvent to form a uniform tar gasification slag suspension, dropping the suspension into a receiving liquid to form a ball, and then performing polymerization and solidification; and then performing carbonization to form a microporous structure, and then performing alkali washing and acid washing to obtain a gasification tar-based micro-mesoporous carbon ball. The application utilizes the high-temperature thermal plasticity and medium-temperature crosslinking property of tar to realize pore forming and template-free regulation and control of the microporous structure; the gasification slag is used as a mesoporous template and a carbon precursor, the ratio of the tar to the gasification slag is adjusted, and the mesoporous structure is regulated and controlled, so that the gasification tar-based carbon ball with low cost, micro-mesoporous and convenient adjustment is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon materials, and in particular relates to a biomass gasification tar-based porous carbon ball and a preparation method and application thereof. Background Art

[0002] Biomass tar is a black or viscous paste-like solid produced during the biomass gasification process. Its composition is complex, primarily containing various pollutants, including benzene series, polycyclic aromatic hydrocarbons, nitrogen- and sulfur-containing heterocyclic compounds, and heavy metals. Tar processing methods include extraction and centrifugation, oil residue collection, brick-making fuel, and activated carbon production. Due to its high carbon content, rich content of cross-linkable phenolic compounds, and strong plasticity, it is an excellent precursor for the preparation of porous carbon materials.

[0003] Under pyrolysis conditions, tar undergoes a thermoplastic phase and a medium-temperature cross-linking and polycondensation phase. Increasing the pyrolysis rate weakens the cross-linking and polycondensation reaction, increasing the size and number of pores. Prolonging the dwell time at the final temperature gradually depolymerizes the macromolecular structure, making cracking more pronounced and promoting the formation of more micropores. Furthermore, the pyrolysis rate alters the release of volatiles, with the precipitates primarily consisting of CO2, CO, and CH4. As the pyrolysis rate increases, the volatiles' precipitation pattern changes from slow, long-term precipitation to rapid, short-term precipitation. This rapid release also promotes the formation of more micropores.

[0004] On the other hand, gasification slag is also a solid residue produced as a byproduct of the gasification process. It is mainly composed of carbon, silica, alumina, calcium oxide, and some other metal oxides. It can be divided into two components: inorganic minerals and residual carbon. It is cheap and easy to obtain, and has the same characteristics as tar. Inorganic minerals are mainly spherical particles, accounting for as much as 45% to 92%, and are good and abundant mesoporous templates. The residual carbon has a flocculent and porous form, has a certain degree of graphitization and a large specific surface area, and is also a good precursor for preparing porous carbon materials.

[0005] CN116199207B discloses a method for preparing coal tar pitch-based three-dimensional hierarchical porous carbon for lithium-ion battery negative electrodes, using sodium carbonate and silica as dual templates and coal tar pitch as a carbon source to prepare coal tar pitch-based three-dimensional hierarchical porous carbon. However, this method uses additional pore-forming agents such as sodium carbonate as a microporous template and silica as a mesoporous template to achieve pore structure regulation, and the pore-making cost is relatively high. Similarly, CN118373402A discloses a nitrogen-doped wood tar resin-based carbon material for supercapacitors and a preparation method thereof, using wood tar as a carbon source, a nitrogen-containing polymer precursor as a nitrogen source, small molecule aldehydes for cross-linking, and potassium hydroxide, potassium carbonate, oxalic acid, etc. as activators to prepare a high specific surface area memory carbon material.

[0006] The existing methods do not fully utilize the high-temperature thermoplasticity and medium-temperature cross-linking properties of tar to achieve pore formation, and a large amount of template agents are introduced to form pores, resulting in high pore formation costs. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention utilizes the high-temperature thermoplasticity and medium-temperature cross-linking properties of tar to achieve pore formation, and realizes convenient template-free regulation of the microporous structure through the heating rate, termination temperature, and holding time; by using the gasified slag with the same source and easy to obtain as the mesoporous template and carbon precursor, by adjusting the ratio of tar to gasified slag, convenient regulation of the mesoporous structure is achieved, and finally low-cost, micro-mesoporous and conveniently adjustable gasified tar-based carbon balls are prepared, which can be applied to N2 adsorption, CO2 adsorption, H2S adsorption, VOC adsorption, light hydrocarbon separation, hydrogen storage and other fields, realizing the coordinated resource utilization of gasified tar and gasified slag, and at the same time is expected to solve the problem of difficult separation of gasified tar and tar residue.

[0008] To achieve the above object, the present invention first provides a method for preparing biomass gasification tar-based porous carbon balls, which comprises the following steps:

[0009] A. Mixing tar, polyacrylonitrile and an organic solvent, dissolving them to obtain a mixed liquid, adding the gasified slag to the mixed liquid, and mixing them evenly to obtain a tar gasified slag suspension;

[0010] B. dropping the suspension obtained in step A into a receiving liquid to form pellets through polymerization and solidification, followed by filtration (usually by suction filtration), washing, drying and graded oxidation to obtain gasified tar-based carbon pellets;

[0011] C. Carbonizing the gasified tar-based carbon balls obtained in step B to form a microporous structure to obtain gasified tar-based microporous carbon balls, and then washing them with alkali solution and acid solution, and then washing and drying them to obtain gasified tar-based micro-mesoporous carbon balls;

[0012] In step A, the mass concentration of tar in the mixed liquid is 10 to 70 wt.%;

[0013] In step A, the mass concentration of polyacrylonitrile in the mixed solution is 0 to 10 wt.%;

[0014] In step A, the mass concentration of the gasified slag in the suspension is 10-20 wt.%.

[0015] In the present invention, polyacrylonitrile is added mainly to increase the strength of the subsequent carbon balls. Tar carbon balls are generally stronger than ordinary raw material carbon balls. Therefore, when the strength requirement is not high, polyacrylonitrile can be omitted.

[0016] In the present invention, the organic solvent used can be any type of organic solvent as long as its solubility in tar and its boiling point meet the dissolution temperature requirements and it does not chemically react with the raw materials in the system. Therefore, many types of organic solvents in the art are suitable for the present invention. Specifically, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step A, the organic solvent is at least one of ethanol, tetrahydrofuran, acetone, xylene, toluene, benzene, carbon disulfide, DMF or DMAc.

[0017] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step A, the dissolution conditions are stirring at 40-80° C. for 1-2 hours.

[0018] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step A, the gasification slag is at least one of biomass gasification slag or coal gasification slag.

[0019] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step A, the particle size of the gasification slag is 100-200 mesh (before use, it is first ground or ball-milled and sieved to obtain gasification slag with a particle size of 100-200 mesh).

[0020] In the above-mentioned method for preparing porous carbon balls based on biomass gasification tar, in step A, the mixing conditions are stirring at 40-80°C for 1-2 hours. Mixing at a preferred temperature avoids excessive tar viscosity at too low a temperature, which is not conducive to ball dripping.

[0021] Preferably, in the above-mentioned preparation method of biomass gasification tar-based porous carbon balls, when the micropore volume is 0.25 to 0.5 cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of tar in the mixed solution in step A is controlled to be 50-70wt.%; when the mesoporous volume is 0.4-0.8cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of the gasified slag in the suspension in step A is controlled to be 17-20wt.%; when the micropore volume is 0.25-0.5cm 3 / , and the mesopore volume is 0.4~0.8cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of tar in the mixed solution in step A is controlled to be 50-70wt.%, and the mass concentration of gasified slag in the suspension in step A is controlled to be 17-20wt.%.

[0022] In the present invention, the receiving liquid used only needs to satisfy the requirements of not dissolving tar and gasified slag, not chemically reacting with the raw materials in the system, and having good mutual solubility with the organic solvent. Therefore, more types of receiving liquids in this area are applicable to the present invention. Specifically, in the preparation method of the above-mentioned biomass tar-based porous carbon balls, in step b, the receiving liquid is at least one of water, ethanol aqueous solution or isopropanol aqueous solution. The concentration of ethanol aqueous solution and isopropanol aqueous solution can be 5% to 20vol.%. In the present invention, the amount of receiving liquid is not required, and generally 200 to 300mL of receiving liquid is used for 30 to 50mL of suspension.

[0023] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step B, the method of dropping the suspension obtained in step A into the receiving liquid is: the suspension obtained in step A is loaded into a syringe, the inner diameter of the syringe needle is controlled to be 0.5-3.0 mm, and the balls are dropped into the receiving liquid through the syringe.

[0024] In the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step B, during the ball dropping process, the dropping rate is controlled to be 1 to 5 seconds per drop.

[0025] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step B, during the ball dropping process, the receiving liquid is stirred at a rotation speed of 200 to 1000 revolutions per minute at room temperature.

[0026] In the present invention, after the suspension is dripped into the receiving liquid, it is polymerized and solidified to form relatively strong spherical or quasi-spherical particles.

[0027] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step B, the washing is: washing with water 2 to 10 times.

[0028] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step B, the drying is: heating to 100-120°C at a heating rate of 1-3°C / min and drying for 4-6 hours.

[0029] In the present invention, the strength of the carbon balls is improved by strictly controlling the graded oxidation. In the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step B, the graded oxidation is as follows: in an air atmosphere, the temperature is increased at a rate of 1-3°C / min to 170-190°C, and kept at this temperature for 1-3 hours; the temperature is further increased at a rate of 1-3°C / min to 210-220°C, and kept at this temperature for 1-3 hours; the temperature is further increased at a rate of 1-3°C / min to 230-240°C, and kept at this temperature for 1-3 hours; the temperature is further increased at a rate of 1-3°C / min to 250-260°C, and kept at this temperature for 1-3 hours; the temperature is further increased at a rate of 1-3°C / min to 280-300°C, and kept at this temperature for 1-3 hours.

[0030] Wherein, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the heating rate of the carbonization is 5 to 20°C / min.

[0031] Wherein, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the carbonization temperature is 600-950°C.

[0032] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the carbonization time is 1 to 4 hours.

[0033] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the alkali washing method is: adding the gasification tar-based microporous carbon balls into alkali solution, stirring at 70-90°C for 1-3 hours.

[0034] Among them, in the preparation method of the above-mentioned biomass gasification tar-based porous carbon balls, in step C, the alkali in the alkali solution is at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, potassium phosphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, potassium citrate or sodium citrate.

[0035] Wherein, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the concentration of the alkali solution is 5 to 20 wt.%.

[0036] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, during the alkali washing process, the mass ratio of alkali in the alkali solution to the gasification tar-based microporous carbon balls is 0.5 to 2:1.

[0037] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the acid washing method is: adding the carbon balls after alkali washing into acid solution, stirring at 70-90°C for 1-3 hours.

[0038] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the acid solution is at least one of sulfuric acid, hydrochloric acid, phosphoric acid or acetic acid.

[0039] Wherein, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the concentration of the acid solution is 1 to 2 mol / L.

[0040] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, during the acid process, the mass volume ratio of gasification tar-based microporous carbon balls and acid solution is 1g:20mL~50mL.

[0041] Among them, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the washing is: washing with water until neutral.

[0042] Wherein, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, in step C, the drying temperature is 100-120°C.

[0043] Among them, the preparation method of biomass gasification tar-based porous carbon balls, when the micropore volume is 0.25-0.5cm 3 / g of gasified tar-based micro-mesoporous carbon balls, in step C, the carbonization heating rate is controlled to be 10-20°C / min, the carbonization temperature is controlled to be 750-950°C, and the carbonization time is controlled to be 2-4h.

[0044] The present invention also provides a biomass gasification tar-based porous carbon ball, which is prepared by the above-mentioned preparation method of the biomass gasification tar-based porous carbon ball. The biomass gasification tar-based porous carbon ball is spherical or quasi-spherical particles with a size of 0.3 to 2.8 mm and a specific surface area of ​​900 to 1300 m 2 / g, micropore volume 0.25~0.5cm 3 / g, mesopore volume 0.4~0.8cm 3 / g, total pore volume 0.2~1.3cm 3 / g, and the average compressive strength is not less than 20N / grain.

[0045] The present invention also provides a method for preparing biomass tar-based porous carbon balls, which comprises the following steps:

[0046] a. mixing tar, polyacrylonitrile and an organic solvent, and dissolving them to obtain a mixed solution;

[0047] b. dropping the mixed solution obtained in step a into a receiving solution to form granules through polymerization and solidification, followed by filtration (usually by suction filtration), washing, drying and graded oxidation to obtain tar-based carbon granules;

[0048] c. carbonizing the tar-based carbon balls obtained in step b to form a microporous structure to obtain tar-based microporous carbon balls;

[0049] In step a, the mass concentration of tar in the mixed liquid is 10 to 70 wt.%;

[0050] In step a, the mass concentration of polyacrylonitrile in the mixed solution is 0 to 10 wt.%.

[0051] In the present invention, the organic solvent used can be any type of organic solvent as long as its solubility in tar and its boiling point meet the dissolution temperature requirements and it does not chemically react with the raw materials in the system. Therefore, many types of organic solvents in the art are suitable for the present invention. Specifically, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step a, the organic solvent is at least one of ethanol, tetrahydrofuran, acetone, xylene, toluene, benzene, carbon disulfide, DMF, or DMAc.

[0052] Among them, in the preparation method of the above-mentioned biomass tar-based porous carbon balls, in step a, the dissolution conditions are stirring at 40-80°C for 1-2 hours.

[0053] Preferably, the above-mentioned method for preparing biomass tar-based porous carbon balls is to prepare micropores with a pore volume of 0.25 to 0.5 cm 3 / g of tar-based microporous carbon balls, the mass concentration of tar in the mixed solution in step a is controlled to be 50-70wt.%.

[0054] In the present invention, the receiving liquid used only needs to satisfy the requirement of not dissolving tar, and at the same time, having good mutual solubility with the organic solvent, and not chemically reacting with the raw materials in the system, so the receiving liquid of more types in this area is applicable to the present invention. Specifically, in the preparation method of the above-mentioned biomass tar-based porous carbon balls, in step b, the receiving liquid is at least one of water, ethanol aqueous solution or isopropanol aqueous solution. The volume concentration of ethanol aqueous solution and isopropanol aqueous solution can be 5% to 20vol.%. In the present invention, the consumption of the receiving liquid is not required, and generally 200 to 300mL of receiving liquid is used for 30 to 50mL of mixed solution.

[0055] Among them, in the above-mentioned preparation method of biomass tar-based porous carbon balls, in step b, the method of dropping the mixed liquid obtained in step a into the receiving liquid is: the mixed liquid obtained in step a is loaded into a syringe, the inner diameter of the syringe needle is controlled to be 0.5-3.0 mm, and the balls are dropped into the receiving liquid through the syringe.

[0056] Among them, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step b, during the ball dropping process, the dropping rate is controlled to be 1 to 5 seconds per drop.

[0057] Among them, in the preparation method of the above-mentioned biomass tar-based porous carbon balls, in step b, during the ball dropping process, the receiving liquid is stirred at a rotation speed of 200 to 1000 revolutions per minute at room temperature.

[0058] Wherein, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step b, the washing is: washing with water 2 to 10 times.

[0059] Among them, in the preparation method of the above-mentioned biomass tar-based porous carbon balls, in step b, the drying is: heating to 100-120°C at a heating rate of 1-3°C / min and drying for 4-6 hours.

[0060] Among them, in the preparation method of the above-mentioned biomass tar-based porous carbon balls, in step b, the graded oxidation is: in an air atmosphere, the heating rate is 1-3°C / min, the temperature is raised to 170-190°C, and kept warm for 1-3 hours; the heating rate is continued to be 1-3°C / min, the temperature is raised to 210-220°C, and the temperature is kept warm for 1-3 hours; the heating rate is continued to be 1-3°C / min, the temperature is raised to 230-240°C, and the temperature is kept warm for 1-3 hours; the heating rate is continued to be 1-3°C / min, the temperature is raised to 250-260°C, and the temperature is kept warm for 1-3 hours; the heating rate is continued to be 1-3°C / min, the temperature is raised to 280-300°C, and the temperature is kept warm for 1-3 hours.

[0061] Wherein, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step c, the heating rate of the carbonization is 5 to 20°C / min.

[0062] Wherein, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step c, the carbonization temperature is 600-950°C.

[0063] Wherein, in the above-mentioned method for preparing biomass tar-based porous carbon balls, in step c, the carbonization time is 1 to 4 hours.

[0064] Preferably, the above-mentioned method for preparing biomass tar-based porous carbon balls is to prepare micropores with a pore volume of 0.25 to 0.5 cm 3 / g of tar-based microporous carbon balls, in step c, the carbonization heating rate is controlled to be 10-20°C / min, the carbonization temperature is controlled to be 750-950°C, and the carbonization time is controlled to be 2-4h.

[0065] The present invention also provides a biomass tar-based porous carbon ball, which is prepared by the above-mentioned preparation method of the biomass tar-based porous carbon ball. The biomass tar-based porous carbon ball is spherical or quasi-spherical particles with a size of 0.3 to 2.8 mm and a specific surface area of ​​200 to 800 m 2 / g, micropore volume 0.25~0.5cm 3 / g, mesopore volume 0.2~0.4cm 3 / g, total pore volume 0.2~1.0cm 3 / g, and the average compressive strength is not less than 15N / grain.

[0066] The present invention also provides the biomass gasification tar-based porous carbon balls prepared by the above-mentioned preparation method of the biomass gasification tar-based porous carbon balls, the above-mentioned biomass gasification tar-based porous carbon balls, the biomass tar-based porous carbon balls prepared by the above-mentioned preparation method of the biomass tar-based porous carbon balls, or the above-mentioned biomass tar-based porous carbon balls, and their use in N2 adsorption, CO2 adsorption, H2S adsorption, VOC adsorption, light hydrocarbon separation or hydrogen storage.

[0067] Beneficial effects of the present invention:

[0068] The present invention firstly uses the high-temperature thermoplasticity and medium-temperature cross-linking properties of tar to realize pore formation. During carbonization, the macromolecular structure of tar gradually depolymerizes, cracks significantly, and the volatile matter precipitates quickly in a short time to promote the formation of more micropores. Therefore, the microporous structure can be conveniently regulated without a template by adjusting the heating rate, the termination temperature, and the holding time. Secondly, the gasified slag with the same source and easy to obtain is used as the mesoporous template and carbon precursor. It is known that the ash content and metal oxides of the gasified slag account for 45% to 92%. Therefore, the convenient regulation of the micro-mesoporous structure can be achieved by adjusting the ratio of tar to gasified slag. It is proposed that when the preparation is mainly micropores (the pore volume of the micropores is 0.25 to 0.5 cm 3 / g) of porous carbon balls, the pore formation by tar self-cracking and volatilization is dominant, so the mass concentration of tar is 50-70wt.%; when the mesopores are the main ones (mesopore volume is 0.4-0.8cm 3 / g) of porous carbon balls, the gasified slag self-mesoporous template to achieve mesopore volume enhancement, the mass concentration is preferably 17-20wt.%, and finally low-cost, conveniently adjustable micro-mesoporous gasified tar-based carbon balls are prepared.

[0069] In addition, the present invention also utilizes the characteristics of tar that is rich in phenolic compounds with good cross-linkability, strong plasticity, and easy molding of soft carbon to achieve one-step cross-linking copolymerization molding, and prepares high-strength carbon balls through graded oxidation. When used in the fields of N2 adsorption, CO2 adsorption, H2S adsorption, VOC adsorption, light hydrocarbon separation, hydrogen storage, etc., compared with traditional powdered carbon materials, it has excellent characteristics such as easy transportation, easy filling, reduced bed pressure, no flying powder, and easy recycling.

[0070] The tar-based porous carbon balls prepared in the present invention have an average compressive strength of not less than 15N / particle and a specific surface area of ​​200 to 800m 2 / g, micropore volume 0.25~0.5cm 3 / g, mesopore volume 0.2~0.4cm 3 / g, total pore volume 0.2~1.0cm 3 / g; gasified tar-based porous carbon balls, with an average compressive strength of not less than 20N / particle and a specific surface area of ​​900-1300m 2 / g, micropore volume 0.25~0.5cm 3 / g, mesopore volume 0.4~0.8cm 3 / g, total pore volume 0.2~1.3cm 3 / g; the CO2 adsorption performance of gasification tar-based porous carbon balls was tested. Under the conditions of gravimetric adsorption test at 25℃ and 1bar CO2, the CO2 adsorption capacity reached 2.5mmol / g; under the conditions of gravimetric adsorption test at 30℃ and 1bar CO2, the CO2 adsorption capacity reached 1.3mmol / g. After 30 continuous adsorption and desorption cycles of the adsorbent, the CO2 adsorption capacity remained stable at 1.2mmol / g, which has the potential for large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is a physical picture of the tar-based microporous carbon balls obtained in Example 1.

[0072] Figure 2 This is a physical picture of the gasified tar-based micro-mesoporous carbon balls obtained in Example 2.

[0073] Figure 3 These are the N2 adsorption and desorption curves of the high-strength tar-based carbon balls and tar-based microporous carbon balls obtained in Example 1.

[0074] Figure 4 This is the mesopore size distribution diagram of the tar-based microporous carbon balls obtained in Example 1.

[0075] Figure 5 This is the pore size distribution diagram of the tar-based microporous carbon balls obtained in Example 1.

[0076] Figure 6 These are the N2 adsorption and desorption curves of the high-strength gasified tar-based carbon balls and gasified tar-based micro-mesoporous carbon balls obtained in Example 2.

[0077] Figure 7 These are the CO2 adsorption curves of the high-strength gasified tar-based carbon balls and gasified tar-based micro-mesoporous carbon balls obtained in Example 2.

[0078] Figure 8 This is the mesopore size distribution diagram of the gasified tar-based micro-mesoporous carbon balls obtained in Example 2.

[0079] Figure 9 This is the pore size distribution diagram of the gasified tar-based micro-mesoporous carbon balls obtained in Example 2. DETAILED DESCRIPTION

[0080] The present invention is further described in detail below through examples, but the protection scope of the present invention is not limited to the scope of the examples.

[0081] Example 1: Non-gasified slag microporous carbon balls

[0082] First, a tar-polyacrylonitrile solution was prepared by dissolving tar and polyacrylonitrile simultaneously in DMF at mass concentrations of 60 wt.% tar and 5 wt.% polyacrylonitrile, respectively. The tar solution was stirred and dissolved at 60°C for 1 hour to form a uniform tar solution. The tar solution was placed in a syringe with a 2 mm diameter and the tar droplets were dripped into the stirred aqueous solution at a rate of 3 to 5 seconds per drop, beginning the tar-carbon granulation experiment. Due to the principle of two-phase immiscibility, the tar solution gradually polymerized and solidified in the aqueous solution. As the DMF was gradually exchanged and dissolved, the tar droplets polymerized and solidified into relatively solid spherical particles. After granulation, the carbon granules were collected by filtration and washed 5 to 10 times with deionized water.

[0083] The carbon balls were placed in an oven and dried at a heating rate of 1°C / min to 100°C in an air atmosphere for 4 to 6 hours. Subsequently, the temperature was raised to 190°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 220°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 230°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 250°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 280°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 3 hours, and then naturally cooled to room temperature to obtain high-strength tar-based carbon balls.

[0084] Subsequently, the high-strength tar-based carbon balls were carbonized by heating the temperature from room temperature to 700°C at a rate of 10°C / min in a nitrogen atmosphere and maintaining the temperature at 700°C for 2 h to obtain high-strength tar-based microporous carbon balls. Figure 1 As shown (in this embodiment, mesopores were not formed by gasification slag, so acid washing and alkali washing were not performed).

[0085] Table 1 Strength of tar-based microporous carbon balls obtained in Example 1

[0086]

[0087] Example 2: Fumed slag tar micro-mesoporous carbon balls

[0088] First, a tar-polyacrylonitrile solution was prepared by dissolving tar and polyacrylonitrile simultaneously in DMF at mass concentrations of 60 wt.% tar and 5 wt.% polyacrylonitrile, respectively. The tar solution was stirred and dissolved at 60°C for 1 hour. Subsequently, fumed slag at a mass concentration of 17 wt.% was added and stirred and dispersed evenly at 60°C for 1 hour to form a uniform fumed slag-tar suspension. The fumed slag-tar suspension was loaded into a 2mm diameter syringe. Tar droplets were dripped into the stirring aqueous solution at a rate of 3-5 seconds per drop. This initiated the tar-carbon pelletization experiment. The tar droplets polymerized and solidified into relatively solid spherical particles. After pelletization, the carbon pellets were collected by filtration and washed 5-10 times with deionized water.

[0089] The carbon balls were placed in an oven and dried at a heating rate of 1°C / min to 100°C in an air atmosphere for 4 to 6 hours. Subsequently, the temperature was raised to 190°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 220°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 230°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 250°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 1 hour; the temperature was raised to 280°C in an air atmosphere at a heating rate of 1°C / min and kept at that temperature for 3 hours, and then naturally cooled to room temperature to obtain high-strength gasified tar-based carbon balls.

[0090] Subsequently, the high-strength gasified tar-based carbon balls were carbonized from room temperature at a heating rate of 10°C / min to 700°C in a nitrogen atmosphere and maintained at 700°C for 2 hours to prepare gasified tar-based microporous carbon balls. Then, the gasified tar-based microporous carbon balls were immersed in 100mL of 10wt.% KOH solution (carbon balls and potassium hydroxide mass ratio 1:1), and then activated in a magnetic stirrer at 80°C for 3 hours. Subsequently, the carbon balls after alkali activation were added to 1M dilute hydrochloric acid (HCl), stirred at 80-90°C for 1-3 hours, and then washed with water until neutral, and dried at 105°C to prepare high-strength gasified tar-based micro-mesoporous carbon balls, such as Figure 2 shown.

[0091] Table 2 Strength of gasified tar-based carbon balls obtained in Example 2

[0092]

[0093] Table 3 Carbon ball pore structure

[0094]

[0095] The strength, specific surface area and CO2 adsorption performance of the carbon balls were verified. The N2 adsorption and desorption curves of the high-strength tar-based carbon balls and tar-based microporous carbon balls obtained in Example 1 are shown in Figure 2. Figure 3As shown in the figure, the mesopore size distribution and micropore size distribution of the tar-based microporous carbon balls obtained in Example 1 are shown in the figure. Figure 4 and Figure 5 As shown; Example 2 obtained high strength gasification tar based carbon balls and gasification tar based micro-mesoporous carbon balls N2 adsorption and desorption curves are as shown Figure 6 As shown in Figure 2, the CO2 adsorption curves of the high-strength gasification tar-based carbon balls and gasification tar-based micro-mesoporous carbon balls obtained in Example 2 are as follows: Figure 7 As shown in the figure, the mesopore size distribution and micropore size distribution of the gasified tar-based micro-mesoporous carbon balls obtained in Example 2 are shown in the figure. Figure 8 and Figure 9 shown.

[0096] The strength tester showed that the average strength of the tar-based microporous carbon balls was 17.2N. The BET specific surface area test showed that the specific surface area of ​​the high-strength tar-based microporous carbon balls was 759.8 cm 2 / g, micropore volume reaches 0.295cm 3 / g; the specific surface area of ​​high-strength gasified tar-based micro-mesoporous carbon balls reaches 1188.9 cm 3 / g, micropore volume reaches 0.421cm 3 / g, and the mesopore volume reaches 0.591cm 3 / g.

[0097] Depend on Figure 3 It can be seen that the N2 adsorption isotherm (77K) of Example 1 shows a type I isotherm feature at a relative pressure of 0-0.1, and the N2 adsorption amount increases significantly, indicating that the sample has relatively developed micropores, V mico 0.295m 3 / g; no obvious return ring was formed during the desorption stage, indicating that the mesopore volume was small.

[0098] Depend on Figure 6 It can be seen that the N2 adsorption isotherm of Example 2 (77K) shows a type I isotherm feature at a relative pressure of 0-0.1, and the N2 adsorption amount increases significantly, indicating that the sample has relatively developed micropores, V mico 0.421m 3 / g; it shows type IV isotherm characteristics at a relative pressure of 0.4 to 1, and there is an obvious H4 type hysteresis in the desorption stage. The type IV isotherm is due to the capillary condensation phenomenon caused by multi-layer adsorption in the mesopores, and at the same time, a clear hysteresis loop is formed, indicating that the sample has a relatively developed mesopore. meso 0.591m 3 / g.

[0099] Under the conditions of volume adsorption test at 25℃ and 1bar CO2, the CO2 adsorption capacity of high-intensity gasification tar-based micro-mesoporous carbon balls reached 4.0mmol / g; Figure 7 In the gravimetric adsorption test at 30°C and 1 bar CO2, the CO2 adsorption capacity reached 1.6 mmol / g, indicating that it has good industrial application potential in the fields of flue gas purification and separation.

Claims

1. A method for preparing biomass gasification tar-based porous carbon balls, characterized by: The following steps are involved: A. Mixing tar, polyacrylonitrile and an organic solvent, dissolving them to obtain a mixed liquid, adding the gasified slag to the mixed liquid, and mixing them evenly to obtain a tar gasified slag suspension; B. dropping the suspension obtained in step A into a receiving liquid to form pellets through polymerization and solidification, and then filtering, washing, drying and graded oxidation to obtain gasified tar-based carbon pellets; C. Carbonizing the gasified tar-based carbon balls obtained in step B to form a microporous structure to obtain gasified tar-based microporous carbon balls, and then washing them with alkali solution and acid solution, and then washing and drying them to obtain gasified tar-based micro-mesoporous carbon balls; In step A, the mass concentration of tar in the mixed liquid is 10-70wt.%; In step A, the mass concentration of polyacrylonitrile in the mixed solution is 0-10wt.%; In step A, the mass concentration of the gasified slag in the suspension is 10-20 wt.%; In step A, the organic solvent is at least one of ethanol, tetrahydrofuran, acetone, xylene, toluene, benzene, carbon disulfide, DMF or DMAc; In step B, the receiving liquid is at least one of water, ethanol aqueous solution or isopropanol aqueous solution; In step B, the graded oxidation is as follows: in an air atmosphere, the temperature is raised to 170-190°C at a heating rate of 1-3°C / min, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 210-220°C, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 230-240°C, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 250-260°C, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 280-300°C, and kept warm for 1-3 hours; In step C, the carbonization heating rate is 5-20°C / min; In step C, the carbonization temperature is 600-950°C; In step C, the carbonization time is 1 to 4 hours.

2. The method for preparing biomass gasification tar-based porous carbon balls according to claim 1, characterized in that: At least one of the following must be met: In step A, the dissolution condition is stirring at 40-80° C. for 1-2 hours; In step A, the gasification slag is at least one of biomass gasification slag or coal gasification slag; In step A, the particle size of the gasified slag is 100-200 mesh; In step A, the mixing condition is stirring at 40-80° C. for 1-2 hours.

3. The method for preparing biomass gasification tar-based porous carbon balls according to claim 1, characterized in that: When the pore volume of the prepared micropores is 0.25~0.5cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of tar in the mixed solution in step A is controlled to be 50-70wt.%; when the mesoporous volume is 0.4-0.8cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of the gasified slag in the suspension in step A is controlled to be 17-20wt.%; when the micropore volume is 0.25-0.5cm 3 / g, and the mesopore volume is 0.4~0.8cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of tar in the mixed solution in step A is controlled to be 50-70wt.%, and the mass concentration of gasified slag in the suspension in step A is controlled to be 17-20wt.%.

4. The method for preparing biomass gasification tar-based porous carbon balls according to claim 1, characterized in that: At least one of the following must be met: In step B, the method of dropping the suspension obtained in step A into the receiving solution is as follows: the suspension obtained in step A is loaded into a syringe, the inner diameter of the syringe needle is controlled to be 0.5-3.0 mm, and the beads are dropped into the receiving solution through the syringe; In step B, during the ball dropping process, the dropping rate is controlled to be 1-5s / drop; In step B, during the ball dropping process, the receiving solution is stirred at a speed of 200 to 1000 rpm at room temperature; In step B, the washing is: washing with water 2 to 10 times; In step B, the drying is as follows: heating the mixture to 100-120° C. at a heating rate of 1-3° C. / min and drying the mixture for 4-6 hours.

5. The method for preparing biomass gasification tar-based porous carbon balls according to claim 1, characterized in that: At least one of the following must be met: In step C, the alkali washing method is: adding the gasified tar-based microporous carbon balls into alkali solution, stirring at 70-90° C. for 1-3 hours; In step C, the alkali in the alkali solution is at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, potassium phosphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, potassium citrate or sodium citrate; In step C, the concentration of the alkali solution is 5-20wt.%; In step C, during the alkaline washing process, the mass ratio of alkali to gasified tar-based microporous carbon balls in the alkaline solution is 0.5-2:1; In step C, the acid washing method is: adding the alkali-washed carbon balls into acid solution, stirring at 70-90° C. for 1-3 hours; In step C, the acid solution is at least one of sulfuric acid, hydrochloric acid, phosphoric acid or acetic acid; In step C, the concentration of the acid solution is 1-2 mol / L; In step C, during the acidic process, the mass volume ratio of gasified tar-based microporous carbon balls and acid solution is 1 g: 20 mL to 50 mL; In step C, the washing is: washing with water until neutral; In step C, the drying temperature is 100-120°C.

6. The method for preparing biomass gasification tar-based porous carbon balls according to any one of claims 1 to 5, characterized in that: When the pore volume of the prepared micropores is 0.25~0.5cm 3 / g of gasified tar-based micro-mesoporous carbon balls, in step C, the carbonization heating rate is controlled to be 10~20℃ / min, the carbonization temperature is controlled to be 750~950℃, and the carbonization time is controlled to be 2~4h.

7. The biomass gasification tar-based porous carbon balls prepared by the preparation method according to any one of claims 1 to 6 are characterized in that: The biomass gasification tar-based porous carbon balls are spherical or quasi-spherical particles with a size of 0.3-2.8 mm and a specific surface area of ​​900-1300 m 2 / g, and the average compressive strength is not less than 20N / grain.

8. A method for preparing biomass tar-based porous carbon balls, characterized by: The following steps are involved: a. mixing tar, polyacrylonitrile and an organic solvent, and dissolving them to obtain a mixed solution; b. dropping the mixed solution obtained in step a into a receiving solution to form granules through polymerization and solidification, and then filtering, washing, drying and graded oxidation to obtain tar-based carbon granules; c. carbonizing the tar-based carbon balls obtained in step b to form a microporous structure to obtain tar-based microporous carbon balls; In step a, the mass concentration of tar in the mixed liquid is 10-70wt.%; In step a, the mass concentration of polyacrylonitrile in the mixed solution is 0-10wt.%; In step a, the organic solvent is at least one of ethanol, tetrahydrofuran, acetone, xylene, toluene, benzene, carbon disulfide, DMF or DMAc; In step b, the receiving liquid is at least one of water, ethanol aqueous solution or isopropanol aqueous solution; In step b, the graded oxidation is as follows: in an air atmosphere, the temperature is raised to 170-190°C at a heating rate of 1-3°C / min, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 210-220°C, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 230-240°C, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 250-260°C, and kept warm for 1-3 hours; the temperature is further raised at a heating rate of 1-3°C / min to 280-300°C, and kept warm for 1-3 hours; In step c, the carbonization heating rate is 5-20°C / min; In step c, the carbonization temperature is 600-950°C; In step c, the carbonization time is 1 to 4 hours.

9. The method for preparing biomass tar-based porous carbon balls according to claim 8, characterized in that: When the pore volume of the prepared micropores is 0.25~0.5cm 3 / g of tar-based microporous carbon balls, the mass concentration of tar in the mixed solution in step a is controlled to be 50-70wt.%.

10. The method for preparing biomass tar-based porous carbon balls according to claim 8 or 9, characterized in that: When the pore volume of the prepared micropores is 0.25~0.5cm 3 / g of tar-based microporous carbon balls, in step c, the carbonization heating rate is controlled to be 10-20°C / min, the carbonization temperature is controlled to be 750-950°C, and the carbonization time is controlled to be 2-4h.

11. The biomass tar-based porous carbon balls prepared by the preparation method according to any one of claims 8 to 10 are characterized in that: The biomass tar-based porous carbon balls are spherical or quasi-spherical particles with a size of 0.3-2.8 mm and a specific surface area of ​​200-800 m 2 / g, and the average compressive strength is not less than 15N / grain.

12. Use of the biomass gasification tar-based porous carbon balls prepared by the preparation method according to any one of claims 1 to 6, the biomass gasification tar-based porous carbon balls according to claim 7, the biomass tar-based porous carbon balls prepared by the preparation method according to any one of claims 8 to 10, or the biomass tar-based porous carbon balls according to claim 11 in N2 adsorption, CO2 adsorption, H2S adsorption, VOC adsorption, light hydrocarbon separation or hydrogen storage.

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