Biomass gasification tar-based porous carbon ball as well as preparation method and application thereof

Abstract

The invention discloses a biomass gasification tar-based porous carbon ball as well as a preparation method and application thereof, and belongs to the technical field of carbon materials. In order to realize high-value resource utilization of gasified tar and prepare a micro-mesoporous adjustable hierarchical porous carbon material, the invention provides a preparation method of biomass gasified tar-based porous carbon spheres, which comprises the following steps: mixing tar, gasified slag, polyacrylonitrile and an organic solvent to form a uniform tar gasified slag suspension, dripping the suspension into a receiving liquid, and drying to obtain the biomass gasified tar-based porous carbon spheres. And after polymerization and curing, carbonizing to form a microporous structure, and then carrying out alkali washing and acid washing to obtain the gasified tar-based micro-mesoporous carbon spheres. According to the invention, the high-temperature thermoplasticity and medium-temperature crosslinking property of tar are utilized to realize pore forming, and template-free regulation and control of a microporous structure are realized; the gasified slag is used as a mesoporous template and a carbon precursor, the proportion of tar to the gasified slag is adjusted, regulation and control of a mesoporous structure are achieved, and the gasified tar-based carbon spheres which are low in cost and convenient and adjustable in micro-mesopores are prepared.

Description

Technical Field

[0001] The 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. The tar composition is complex, mainly containing various pollutants such as benzene series, polycyclic aromatic hydrocarbons, nitrogen-containing and sulfur-containing heterocyclic compounds, heavy metals, etc. The treatment methods of tar mainly include extraction centrifugation-oil residue collection, brick burning fuel, and preparation of activated carbon. Due to its high carbon content, rich in phenolic compounds with good cross-linking properties, and strong plasticity, it is a good precursor for the preparation of porous carbon materials.

[0003] Under pyrolysis conditions, tar will go through a thermoplastic stage and a medium-temperature cross-linking polycondensation stage. Increasing the pyrolysis rate can weaken the cross-linking polycondensation reaction and increase the size and number of pores. Prolonging the final temperature residence time can gradually depolymerize the macromolecular structure, making the cracking more obvious and promoting the formation of more micropores. In addition, the pyrolysis rate changes the release of volatiles, and the precipitates are mainly CO2, CO and CH4. As the pyrolysis rate increases, the precipitation form of volatiles changes from long-term slow precipitation to short-term rapid precipitation. The extremely rapid release process will also promote the formation of more micropores.

[0004] On the other hand, gasification slag is also a solid residue produced as a by-product of the gasification process. It is mainly composed of carbon, silicon dioxide, aluminum oxide, 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 is homologous to 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 the preparation of porous carbon materials.

[0005] CN116199207B discloses a method for preparing coal tar pitch-based three-dimensional hierarchical porous carbon for lithium ion battery negative electrode, using sodium carbonate and silicon dioxide 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 silicon dioxide 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, and 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 a high pore formation cost. Summary of the invention

[0007] In view of the shortcomings of the prior art, 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 by adjusting 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, and 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 used in 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 the 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. Mix tar, polyacrylonitrile and an organic solvent, dissolve to obtain a mixed liquid, add the gasified slag to the mixed liquid, mix well, and obtain a tar gasified slag suspension;

[0010] B. dropping the suspension obtained in step A into a receiving liquid, polymerizing and solidifying to form particles, and then filtering (usually by suction filtration), washing, drying and graded oxidation to obtain gasified tar-based carbon balls;

[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 solution is 10-70wt.%;

[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 gasified slag in the suspension is 10-20wt.%.

[0015] In the present invention, polyacrylonitrile is added mainly to increase the strength of 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 selected without adding.

[0016] In the present invention, the organic solvent used only needs to have a solubility in tar and a boiling point that meets the dissolution temperature requirements and does not chemically react with the raw materials in the system, so 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 preparation method of the above-mentioned 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 preparation method of the above-mentioned biomass gasification tar-based porous carbon balls, in step A, the particle size of the gasified slag is 100-200 mesh (before use, it is first ground or ball-milled and sieved to obtain gasified slag with a particle size of 100-200 mesh).

[0020] Among them, in the preparation method of biomass gasification tar-based porous carbon balls, in step A, the mixing condition is stirring at 40-80°C for 1-2 hours. Mixing is carried out at a better temperature to avoid excessive viscosity of tar when the temperature is too low, which is not conducive to ball dripping.

[0021] Preferably, in the above-mentioned method for preparing biomass gasification tar-based porous carbon balls, when the prepared 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 pore volume is 0.4-0.8cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of 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 organic solvents. Therefore, many types of receiving liquids in this field are suitable for 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, there is no requirement for the amount of receiving liquid, generally 30 to 50mL of suspension corresponds to the use of 200 to 300mL of receiving liquid.

[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: loading the suspension obtained in step A into a syringe, controlling the inner diameter of the syringe needle to 0.5-3.0 mm, and dropping the balls into the receiving liquid through the syringe.

[0024] 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 dropping rate is controlled to be 1 to 5 s / drop.

[0025] Among them, in the preparation method of the above-mentioned biomass gasification tar-based porous carbon balls, in step B, during the ball dropping process, the receiving liquid is stirred at a speed of 200 to 1000 revolutions / min 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 firm spherical or quasi-spherical particles.

[0027] Wherein, 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 preparation method of the above-mentioned 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 4-6h.

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

[0030] Among them, 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 method for preparing the above-mentioned 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 preparation method of the above-mentioned 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 1-3h.

[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 preparation method of the above-mentioned 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 preparation method of the above-mentioned 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 1-3h.

[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 method for preparing the above-mentioned 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 acidic process, the mass volume ratio of the gasification tar-based microporous carbon balls and the 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 method for preparing the above-mentioned biomass gasification tar-based porous carbon balls, in step C, the drying temperature is 100-120°C.

[0043] Among them, the preparation method of the biomass gasification tar-based porous carbon balls, when the prepared 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 750-950°C, and the carbonization time is 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 a spherical or quasi-spherical particle 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. Mix tar, polyacrylonitrile and an organic solvent and dissolve them to obtain a mixed solution;

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

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

[0049] In step a, the mass concentration of tar in the mixed solution 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 only needs to have a solubility in tar and a boiling point that meets the dissolution temperature requirements and does not chemically react with the raw materials in the system, so 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 method for preparing the biomass tar-based porous carbon balls has a micropore 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, having good mutual solubility with organic solvents, and not chemically reacting with the raw materials in the system. Therefore, many types of receiving liquids in this field are suitable for 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, there is no requirement for the amount of receiving liquid, generally 30 to 50mL of mixed liquid corresponds to the use of 200 to 300mL of receiving liquid.

[0055] Among them, in the preparation method of the above-mentioned 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: loading the mixed liquid obtained in step a into a syringe, controlling the inner diameter of the syringe needle to 0.5-3.0 mm, and dropping the balls into the receiving liquid through the syringe.

[0056] 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 dropping rate is controlled to be 1 to 5 s / 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 speed of 200 to 1000 revolutions / min at room temperature.

[0058] Wherein, in the preparation method of the above-mentioned 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 1-3h; 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 1-3h; 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 1-3h; 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 1-3h; 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 1-3h.

[0061] Wherein, in the method for preparing the above-mentioned 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 method for preparing the above-mentioned 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 method for preparing the biomass tar-based porous carbon balls has a micropore 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 750-950°C, and the carbonization time is 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 a spherical or quasi-spherical particle 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 biomass gasification tar-based porous carbon balls prepared by the above-mentioned preparation method of 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 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, cracking is obvious, and the volatile matter is quickly precipitated in a short time to promote the formation of more micropores. Therefore, the microporous structure can be conveniently regulated without a template by the heating rate, termination temperature, and holding time. Secondly, the gasified slag with the same source and cheap 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 mesoporous pore 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 was still 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] Fig. 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 by way of 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, prepare a tar polyacrylonitrile solution, dissolve tar and polyacrylonitrile in DMF at the same time, with mass concentrations of tar: 60wt.%; polyacrylonitrile: 5wt.%. Stir and dissolve the tar solution at 60℃ for 1h to form a uniform tar solution. Load the above tar solution into a syringe with a diameter of 2mm, and drip the tar droplets into the stirred aqueous solution at a rate of 3-5s / drop, and start the tar carbon ball granulation experiment. Due to the principle of two-phase immiscibility, the tar solution gradually polymerizes and solidifies in the aqueous solution. As DMF is gradually exchanged and dissolved, the tar droplets polymerize and solidify into relatively solid spherical particles. After the granulation is completed, filter and collect the carbon balls, and wash the carbon balls with deionized water for 5-10 times.

[0083] The carbon balls were placed in an oven, heated at a rate of 1°C / min in an air atmosphere, and heated to 100°C for drying for 4 to 6 hours. Then, the temperature was raised to 190°C in an air atmosphere at a rate of 1°C / min, and kept warm for 1 hour; the temperature was raised to 220°C in an air atmosphere at a rate of 1°C / min, and kept warm for 1 hour; the temperature was raised to 230°C in an air atmosphere at a rate of 1°C / min, and kept warm for 1 hour; the temperature was raised to 250°C in an air atmosphere at a rate of 1°C / min, and kept warm for 1 hour; the temperature was raised to 280°C in an air atmosphere at a rate of 1°C / min, and kept warm 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 in a nitrogen atmosphere at a heating rate of 10°C / min from room temperature to 700°C and maintained at 700°C for 2 h to prepare 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: Gasification slag tar micro-mesoporous carbon balls

[0088] First, prepare a tar polyacrylonitrile solution. Dissolve tar and polyacrylonitrile in DMF at the same time. The mass concentrations are tar: 60wt.%; polyacrylonitrile: 5wt.%. The tar solution is stirred and dissolved at 60℃ for 1h, and then the gasified slag with a mass concentration of 17wt.% is added and stirred and evenly dispersed at 60℃ for 1h to form a uniform gasified slag tar suspension. The aforementioned gasified slag tar suspension is loaded into an injection tube with a diameter of 2mm. The tar droplets are dripped into the stirred aqueous solution at a speed of 3-5s / drop, and the tar carbon ball granulation experiment is started. The tar droplets are polymerized and solidified into relatively solid spherical particles. After the granulation is completed, the carbon balls are collected by filtration and washed with deionized water for 5-10 times.

[0089] The carbon balls were placed in an oven, heated at a rate of 1°C / min in an air atmosphere, heated to 100°C for drying, and the drying time was 4 to 6 hours. Then, in an air atmosphere, the temperature was raised to 190°C at a rate of 1°C / min, and kept warm for 1 hour; in an air atmosphere, the temperature was raised to 220°C at a rate of 1°C / min, and kept warm for 1 hour; in an air atmosphere, the temperature was raised to 230°C at a rate of 1°C / min, and kept warm for 1 hour; in an air atmosphere, the temperature was raised to 250°C at a rate of 1°C / min, and kept warm for 1 hour; in an air atmosphere, the temperature was raised to 280°C at a rate of 1°C / min, and kept warm 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 heated from room temperature to 700°C at a heating rate of 10°C / min in a nitrogen atmosphere, and maintained at 700°C for 2 hours to be carbonized 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 ball and potassium hydroxide mass ratio 1:1), and then activated in a magnetic stirrer at 80°C for 3 hours, and then the carbon balls activated by alkali solution were added to 1M dilute hydrochloric acid (HCl), stirred at 80-90°C for 1-3 hours, and then washed with water to neutrality, 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 3As shown, the mesopore size distribution diagram and micropore size distribution diagram of the tar-based microporous carbon balls obtained in Example 1 are shown in Figure 4 and Figure 5 As shown; the N2 adsorption and desorption curves of the high-strength gasification tar-based carbon balls and gasification tar-based micro-mesoporous carbon balls obtained in Example 2 are as shown Figure 6 As shown, 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, the mesopore pore size distribution diagram and micropore pore size distribution diagram of the gasified tar-based micro-mesoporous carbon balls obtained in Example 2 are shown in Figure 8 and Fig. 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 reached 759.8cm 2 / g, micropore volume up to 0.295cm 3 / g; the specific surface area of ​​high-strength gasification tar-based micro-mesoporous carbon balls is 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 the characteristics of type I isotherm 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 (77K) of Example 2 shows the characteristics of type I isotherm 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 the characteristics of type IV isotherm 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 an obvious hysteresis loop is formed at the same time, indicating that the sample has a relatively developed mesopore, V 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 conditions of weight adsorption test at 30℃ and 1bar CO2, the CO2 adsorption amount reached 1.6mmol / 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 in that: The following steps are involved: A. Mix tar, polyacrylonitrile and an organic solvent, dissolve to obtain a mixed liquid, add the gasified slag to the mixed liquid, mix well, and obtain a tar gasified slag suspension; B. dropping the suspension obtained in step A into a receiving liquid, forming particles through polymerization and solidification, and then filtering, washing, drying and graded oxidation to obtain gasified tar-based carbon balls; 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 solution is 10-70wt.%; In step A, the mass concentration of polyacrylonitrile in the mixed solution is 0 to 10 wt.%; In step A, the mass concentration of gasified slag in the suspension is 10-20wt.%.

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 is met: In step A, the organic solvent is at least one of ethanol, tetrahydrofuran, acetone, xylene, toluene, benzene, carbon disulfide, DMF or DMAc; In step A, the dissolving condition is stirring at 40-80° C. for 1-2 hours; In step A, the gasified slag is at least one of biomass gasified slag or coal gasified slag; In step A, the particle size of the gasified slag is 100-200 mesh; In step A, the uniform 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 0.25-0.5 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 pore volume is 0.4-0.8cm 3 / g of gasified tar-based micro-mesoporous carbon balls, the mass concentration of 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.%.

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 is met: In step B, the receiving solution is at least one of water, ethanol aqueous solution or isopropanol aqueous solution; 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 to 3.0 mm, and the ball is dropped into the receiving liquid through the syringe; In step B, during the ball dropping process, the dropping rate is controlled to be 1 to 5 seconds per 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: heating the temperature to 100-120° C. and drying for 4-6 hours at a heating rate of 1-3° C. / min; In step B, the graded oxidation is as follows: in an air atmosphere, the temperature is increased to 170-190°C at a heating rate of 1-3°C / min, and kept warm for 1-3h; the temperature is continued to be increased at a rate of 1-3°C / min to 210-220°C, and kept warm for 1-3h; the temperature is continued to be increased at a rate of 1-3°C / min to 230-240°C, and kept warm for 1-3h; the temperature is continued to be increased at a rate of 1-3°C / min to 250-260°C, and kept warm for 1-3h; the temperature is continued to be increased at a rate of 1-3°C / min to 280-300°C, and kept warm for 1-3h.

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 is met: In step C, the heating rate of the carbonization is 5 to 20°C / min; In step C, the carbonization temperature is 600-950°C; In step C, the carbonization time is 1 to 4 hours; In step C, the alkali washing method is: adding 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 to 20 wt.%; 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 to 2:1; In step C, the acid washing method is: adding the alkali-washed carbon balls into an acid solution, stirring at 70 to 90° C. for 1 to 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 acid process, the mass volume ratio of the gasified tar-based microporous carbon balls and the 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 0.25-0.5 cm 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 750-950°C, and the carbonization time is 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 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.

8. A method for preparing biomass tar-based porous carbon balls, characterized in that: The following steps are involved: a. Mix tar, polyacrylonitrile and an organic solvent and dissolve them to obtain a mixed solution; b. dropping the mixed solution obtained in step a into a receiving solution, forming particles through polymerization and solidification, and then filtering, washing, drying and graded oxidation to obtain tar-based carbon balls; c. carbonizing the tar-based carbon balls obtained in step b to form a microporous structure, thereby obtaining tar-based microporous carbon balls; In step a, the mass concentration of tar in the mixed solution is 10 to 70 wt.%; In step a, the mass concentration of polyacrylonitrile in the mixed solution is 0 to 10 wt.%.

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 0.25-0.5 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.%.

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 0.25-0.5 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 750-950°C, and the carbonization time is 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 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.

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

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