Process for producing high ignition point plant-based columnar activated carbon

Abstract

The application discloses a production method of high ignition point plant-based columnar activated carbon, and in the process of preparing the plant-based columnar activated carbon, carbonization flue gas generated by carbonization treatment is subjected to cascade condensation recovery to obtain bio-oil, the bio-oil can be refined into light liquid, heavy oil and plant pitch through secondary fractionation, the three fractionation products can be fully utilized in different production links of the columnar activated carbon, and through reasonable utilization of physical properties, the processing by-products can improve the performance of the activated carbon products, so that the prepared activated carbon has the advantages of high ignition point, high bulk density, low ash content and high adsorption performance; meanwhile, the production process fully utilizes the self-produced light liquid, heavy oil and plant pitch, so that there is no need to additionally purchase a binder, the physical properties of the production product are stable due to the specific temperature, the self-produced biochar has good affinity, the strength and porosity of the formed material before activation can be improved, and the performance of the product after activation is enhanced.

Description

Technical Field

[0001] This invention relates to the field of activated carbon adsorption material production technology, and in particular to a method for producing high ignition point plant-based columnar activated carbon. Background Technology

[0002] Most common columnar activated carbon is physical coal-based activated carbon, which is mainly produced by extruding coal powder with binders such as coal tar and pitch into granules, followed by physical carbon activation. Physically produced coal-based activated carbon products have a strength of up to 98% and a specific gravity of 0.45–0.55 g / ml. However, due to the difficulty in activating coal-based physical activated carbon, products commonly available on the market have a CTC (carbon tetrachloride adsorption value) of 40%, while products with a CTC of over 60% require secondary activation, resulting in low product yield. Commonly used phosphoric acid-based plant-based columnar activated carbon is produced by kneading biomass powder with phosphoric acid, forming granules, and then carbon activation. It has high adsorption performance, but suffers from low strength (90–95%) and low specific gravity (0.3–0.4 g / ml). Furthermore, due to the low activation temperature, phosphoric acid-based columnar activated carbon experiences severe pore shrinkage during high-temperature regeneration after use, leading to a significant decrease in adsorption performance. There are few plant-based columnar activated carbons on the market with an ignition point of over 400℃, strength of over 98%, CTC greater than 60%, specific gravity of over 0.4g / ml, and high adsorption capacity, and their production cost is relatively high.

[0003] For example, Chinese patent application CN201510065083.7 discloses a process for producing wood-based columnar activated carbon, which uses lignin, carboxymethyl cellulose, kaolin, and bentonite as binders, making it difficult to produce high-purity, low-ash columnar activated carbon. Chinese patent application CN201811363973.6 discloses a macroporous granular activated carbon and its preparation method, while Chinese patent application CN201410219043.9 discloses a chemical method for preparing granular activated carbon. Both methods use added inorganic agents as catalysts or binders, increasing the cost of agent recovery and the possibility of environmental pollution. They also require highly corrosive equipment and are difficult to produce columnar activated carbon with high ignition point, high purity, and low ash content. Furthermore, Chinese patent application CN201710823764.4 discloses a bamboo-based columnar activated carbon, its preparation method, and its application. This method uses bamboo charcoal as the carbonization material and bamboo tar or bamboo pulp black liquor as the binder, and also adds asphalt and carboxymethyl cellulose as binders. It also suffers from the aforementioned problems. Therefore, how to prepare a plant-based columnar activated carbon with a high ignition point and high adsorption capacity is a research topic of practical significance. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for producing high ignition point plant-based columnar activated carbon with high ignition point, high bulk density and good adsorption performance.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows:

[0006] A method for producing high ignition point plant-based columnar activated carbon includes: processing agricultural and forestry residues into biomass raw materials, then carbonizing them in an oxygen-deficient environment at 350–800°C to obtain carbonized material and carbonized flue gas; the carbonized flue gas is condensed and fractionated in multiple stages to obtain light oil, heavy oil, and asphalt, respectively; the carbonized material is cooled, crushed, and sieved to obtain biochar powder; the biochar powder is then mixed with light oil and water in a predetermined ratio and stirred, and the pH is adjusted to neutral using an acid solution. A carbonized modified slurry is prepared. After dehydration and drying, the carbonized modified slurry forms a carbonized modified dry material. The carbonized modified dry material is then mixed with asphalt in a preset ratio and pulverized to obtain a carbonized modified powder. The carbonized modified powder is then mixed with heavy oil and water in a preset ratio, and after heating, kneading, molding, and drying, a carbonized modified molded material is obtained. Finally, the carbonized modified molded material is placed in an oxygen-deficient environment at 500-950℃ for pore expansion treatment to obtain high ignition point plant-based columnar activated carbon.

[0007] As one possible implementation, this solution further includes the following steps:

[0008] S01. After initial screening and drying of agricultural and forestry residues to a moisture content of less than 15%, iron is removed to obtain biomass raw materials.

[0009] S02. The biomass raw material is carbonized in an oxygen-deficient environment of 350-800℃ to obtain carbonized material and carbonized flue gas. The carbonized flue gas is recovered by indirect stepwise condensation to obtain bio-oil. The carbonized material is cooled, crushed and screened to obtain biochar powder.

[0010] S03. The bio-oil is first fractionated at 160-180℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 180-300℃, and the resulting gas is condensed to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt.

[0011] S04. The biochar powder, light oil and hot water are added to a mixing tank in a mass ratio of 100:1 to 5:1000 to 1500 and stirred. The pH of the mixture is adjusted to neutral using a 1% to 10% acid solution to obtain a carbonized modified slurry.

[0012] S05. The carbonized modified slurry is dehydrated using a filter. After dehydration, it is washed evenly with hot water in the filter in a countercurrent manner, then filtered, dehydrated, and dried by airflow to obtain carbonized modified dry material.

[0013] S06. The carbonized modified dry material and the solid plant asphalt are mixed in a mass ratio of 100:20-30, and then pulverized to obtain carbonized modified powder.

[0014] S07. The carbonized modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:10-15:35-40, and kneaded by heating at 70-100°C, extruded into strips with a specification of 3-6mm, and then dried by mesh belt at 100-160°C until the moisture content is within 10% to obtain the carbonized modified molding material.

[0015] S08. The carbonized modified molding material is put into a rotary furnace with carbon activation at a temperature of 500-950℃. It is first subjected to oxygen-deficient deep carbonization at a temperature range of 500-850℃ for 1-3 hours to achieve preliminary pore expansion. Then, it is subjected to oxygen-deficient activation at a temperature range of 850-950℃ with the addition of water vapor for 1-4 hours to achieve deep pore expansion, and finally, high ignition point columnar activated carbon is obtained.

[0016] As a preferred implementation option, preferably, in this scheme S01, the agricultural and forestry residues are a mixture of one or more of wood chips, bamboo chips, fruit shells, and coconut shells; after iron removal, the agricultural and forestry residues are further subjected to crushing and hot pressing molding.

[0017] As a preferred implementation option, in S02 of this scheme, the carbonization flue gas is further condensed in an indirect stepwise manner to obtain wood gas, which is used as one of the heating fuels in the carbon activation integrated rotary kiln in S08.

[0018] As a preferred implementation option, in this scheme S02, the carbonization temperature is 350-800℃, and the oxygen content in the carbonization atmosphere is less than 1%. The obtained carbonization flue gas is used for indirect cascade condensation to recover bio-oil, and wood gas is obtained and used for activation heating in S08. The carbonized material is crushed by roller crushing and then passed through a 30-mesh sieve.

[0019] As a preferred implementation option, in this scheme S03, the bio-oil fractionation adopts a two-stage temperature-controlled fractionation, with the first-stage fractionation temperature range being 160-180℃ and the second-stage fractionation temperature range being 180-300℃. The gas after fractionation is condensed in a stirred tank with indirect heat exchange.

[0020] As a preferred implementation option, preferably, in this scheme S04, the acid solution is either hydrochloric acid or sulfuric acid.

[0021] As a preferred implementation option, in S05 of this scheme, the carbonized modified slurry is filtered and washed simultaneously using a filter machine, wherein the washing is performed using hot water at 50-80℃ in a countercurrent manner.

[0022] As a preferred implementation option, preferably, in this scheme S06, the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

[0023] As a preferred implementation option, in this scheme S07, the heating and kneading time is 30-60 minutes and the kneading temperature is 70-100℃.

[0024] As a preferred implementation option, preferably, in this scheme S08, the oxygen content of the carbon activation atmosphere in the integrated carbon activation rotary furnace is less than 1%.

[0025] Based on the above, the present invention also provides a high ignition point plant-based columnar activated carbon, which is prepared by the production method described above.

[0026] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0027] (1) In terms of improving product performance, in the process of preparing plant-based columnar activated carbon, the carbonized flue gas generated by carbonization treatment is condensed and recovered in stages to obtain bio-oil. The bio-oil can be refined into light liquid, heavy oil and plant asphalt through two-stage fractionation. These three fractionation products can be fully utilized in different production stages of columnar activated carbon. Through the rational utilization of physical properties, the processing by-products can play the role of improving the performance of activated carbon products, thereby increasing the ignition point, bulk density, ash content and adsorption performance of the obtained activated carbon.

[0028] (2) In terms of production cost and intermediate product resource utilization, the production process of this scheme makes full use of self-produced light liquid, heavy oil and plant asphalt, so that there is no need to purchase additional binders. At the same time, since it is a production product at a specific temperature, its physical properties are stable and it has a good affinity with self-produced biochar, which can improve the strength and porosity of the pre-activated molding material and enhance the performance of the activated product.

[0029] (3) The modifier and binder in this scheme are products of the reuse production process. They can be produced and used by themselves, and can realize the production of high-purity, high-ignition-point plant-based columnar activated carbon. Unlike other columnar activated carbons on the market, it has low organic salt content and low ash content. At the same time, it has the characteristics of high purity, high specific gravity, high ignition point, high strength and high adsorption performance. It is a high-quality activated carbon and has market competitiveness in the fields of solvent recovery, liquid phase purification and gas phase adsorption. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a simplified implementation flowchart of the present invention. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below with reference to the embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment describes a method for producing high ignition point plant-based columnar activated carbon, which includes the following steps:

[0035] S01. Agricultural and forestry residues (a mixture of wood chips, bamboo chips, fruit shells, coconut shells, etc.) are initially screened, dried to a moisture content of less than 15%, then iron is removed, crushed, and hot-pressed to obtain biomass raw materials.

[0036] S02. The biomass raw material is carbonized in an oxygen-deficient environment at 350℃ and with an oxygen content of less than 1% to obtain carbonized material and carbonized flue gas. The carbonized flue gas is recovered by indirect stepwise condensation to obtain bio-oil and wood gas. The carbonized material is cooled, crushed, and screened to obtain biochar powder. The carbonized material is crushed by roller crushing and then screened through a 30-mesh sieve.

[0037] S03. The bio-oil is first fractionated at 160-165℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 180-190℃, and the resulting gas is condensed in an indirect heat exchange stirred tank to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt.

[0038] S04. The biochar powder, light oil and hot water are added to a mixing tank in a mass ratio of 100:5:1000 and stirred. The pH of the mixture is adjusted to neutral using a 1% hydrochloric acid solution to obtain a carbonized modified slurry.

[0039] S05. The carbonized modified slurry is dewatered using a filter. After dewatering, it is washed evenly in the filter with hot water in a countercurrent manner. Then it is filtered, dewatered, and dried by airflow to obtain carbonized modified dry material. The washing is done with hot water at 50-55℃ in a countercurrent manner.

[0040] S06. The carbonized modified dry material and the solid plant asphalt are mixed in a mass ratio of 100:20, and then pulverized to obtain carbonized modified powder, wherein the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

[0041] S07. The carbonized modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:15:35, and then kneaded at 70-75°C for 60 minutes. The mixture is then extruded into 3mm strips and dried on a mesh belt at 100-110°C until the moisture content is below 10%, thus obtaining the carbonized modified molding material.

[0042] S08. The carbonized modified molding material is fed into a rotary kiln for carbon activation at a temperature of 500-950℃. It is first subjected to oxygen-deficient (oxygen content less than 1%) deep carbonization at a temperature of 500℃ for 3 hours to achieve preliminary pore expansion. Then, it is subjected to oxygen-deficient (oxygen content less than 1%) activation at a temperature of 850℃ with the addition of water vapor for 4 hours to achieve deep pore expansion, and finally, high ignition point columnar activated carbon is obtained. Among them, the wood gas obtained in S02 is used as one of the heating fuels in the rotary kiln for carbon activation.

[0043] Example 2

[0044] This embodiment describes a method for producing high ignition point plant-based columnar activated carbon, which includes the following steps:

[0045] S01. Agricultural and forestry residues (a mixture of wood chips, bamboo chips, fruit shells, coconut shells, etc.) are initially screened, dried to a moisture content of less than 15%, then iron is removed, crushed, and hot-pressed to obtain biomass raw materials.

[0046] S02. The biomass raw material is carbonized in an oxygen-deficient environment at 550℃ and with an oxygen content of less than 1% to obtain carbonized material and carbonized flue gas. The carbonized flue gas is recovered by indirect stepwise condensation to obtain bio-oil and wood gas. The carbonized material is cooled, crushed, and screened to obtain biochar powder. The carbonized material is crushed by roller crushing and then screened through a 30-mesh sieve.

[0047] S03. The bio-oil is first fractionated at 165-170℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 230-240℃, and the resulting gas is condensed in an indirect heat exchange stirred tank to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt.

[0048] S04. The biochar powder, light oil and hot water are added to a mixing tank in a mass ratio of 100:3:1300 and stirred. The pH of the mixture is adjusted to neutral using a 5% hydrochloric acid or sulfuric acid solution to obtain a carbonized modified slurry.

[0049] S05. The carbonized modified slurry is dewatered using a filter. After dewatering, it is washed evenly in the filter with hot water in a countercurrent manner. Then it is filtered, dewatered, and dried by airflow to obtain carbonized modified dry material. The washing is carried out in a countercurrent manner with hot water at 60-70℃.

[0050] S06. The carbonized modified dry material and the solid plant asphalt are mixed in a mass ratio of 100:25, and then pulverized to obtain carbonized modified powder, wherein the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

[0051] S07. The carbonized modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:13:37, and then kneaded at 80-85°C for 40 minutes. The mixture is then extruded into 4mm strips and dried on a mesh belt at 130-140°C until the moisture content is below 10%, thus obtaining the carbonized modified molding material.

[0052] S08. The carbonized modified molding material is fed into a rotary kiln for carbon activation at a temperature of 500-950℃. It is first subjected to oxygen-deficient (oxygen content less than 1%) deep carbonization at a temperature of 650℃ for 2 hours to achieve preliminary pore expansion. Then, it is subjected to oxygen-deficient (oxygen content less than 1%) activation at a temperature of 900℃ with the addition of water vapor for 2 hours to achieve deep pore expansion, and finally, high ignition point columnar activated carbon is obtained. Among them, the wood gas obtained in S02 is used as one of the heating fuels in the rotary kiln for carbon activation.

[0053] Example 3

[0054] This embodiment describes a method for producing high ignition point plant-based columnar activated carbon, which includes the following steps:

[0055] S01. Agricultural and forestry residues (a mixture of wood chips, bamboo chips, fruit shells, coconut shells, etc.) are initially screened, dried to a moisture content of less than 15%, then iron is removed, crushed, and hot-pressed to obtain biomass raw materials.

[0056] S02. The biomass raw material is carbonized in an oxygen-deficient environment at 800℃ and with an oxygen content of less than 1% to obtain carbonized material and carbonized flue gas. The carbonized flue gas is recovered by indirect stepwise condensation to obtain bio-oil and wood gas. The carbonized material is cooled, crushed, and screened to obtain biochar powder. The carbonized material is crushed by roller crushing and then screened through a 30-mesh sieve.

[0057] S03. The bio-oil is first fractionated at 175-180℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 290-300℃, and the resulting gas is condensed in an indirect heat exchange stirred tank to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt.

[0058] S04. The biochar powder, light oil and hot water are added to a mixing tank in a mass ratio of 100:1:1500 and stirred. The pH of the mixture is adjusted to neutral using a 10% hydrochloric acid solution to obtain a carbonized modified slurry.

[0059] S05. The carbonized modified slurry is dewatered using a filter. After dewatering, it is washed evenly in the filter with hot water in a countercurrent manner, then filtered, dewatered, and dried by airflow to obtain carbonized modified dry material. The washing is carried out in a countercurrent manner with hot water at 50-80℃.

[0060] S06. The carbonized modified dry material and the solid plant asphalt are mixed in a mass ratio of 100:30, and then pulverized to obtain carbonized modified powder, wherein the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

[0061] S07. The carbonized modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:10:40, and then kneaded at 100°C for 30 minutes. The mixture is then extruded into 5mm strips and dried on a mesh belt at 150-160°C until the moisture content is below 10% to obtain the carbonized modified molding material.

[0062] S08. The carbonized modified molding material is fed into a rotary kiln for carbon activation at a temperature of 500-950℃. It is first subjected to oxygen-deficient (oxygen content less than 1%) deep carbonization at a temperature of 850℃ for 1 hour to achieve preliminary pore expansion. Then, it is subjected to oxygen-deficient (oxygen content less than 1%) activation at a temperature of 950℃ with the addition of water vapor for 1 hour to achieve deep pore expansion, and finally, high ignition point columnar activated carbon is obtained. Among them, the wood gas obtained in S02 is used as one of the heating fuels in the rotary kiln for carbon activation.

[0063] Example 4

[0064] This embodiment describes a method for producing high ignition point plant-based columnar activated carbon, which includes the following steps:

[0065] S01. Agricultural and forestry residues (a mixture of wood chips, bamboo chips, fruit shells, coconut shells, etc.) are initially screened, dried to a moisture content of less than 15%, then iron is removed, crushed, and hot-pressed to obtain biomass raw materials.

[0066] S02. The biomass raw material is carbonized in an oxygen-deficient environment at 500℃ and with an oxygen content of less than 1% to obtain carbonized material and carbonized flue gas. The carbonized flue gas is recovered by indirect stepwise condensation to obtain bio-oil and wood gas. The carbonized material is cooled, crushed, and screened to obtain biochar powder. The carbonized material is crushed by roller crushing and then screened through a 30-mesh sieve.

[0067] S03. The bio-oil is first fractionated at 170-175℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 250-280℃, and the resulting gas is condensed in an indirect heat exchange stirred tank to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt.

[0068] S04. The biochar powder, light oil and hot water are added to a mixing tank in a mass ratio of 100:2:1500 and stirred. The pH of the mixture is adjusted to neutral using a 6% hydrochloric acid solution to obtain a carbonized modified slurry.

[0069] S05. The carbonized modified slurry is dewatered using a filter. After dewatering, it is washed evenly in the filter with hot water in a countercurrent manner, then filtered, dewatered, and dried by airflow to obtain carbonized modified dry material. The washing is carried out in a countercurrent manner with hot water at 50-80℃.

[0070] S06. The carbonized modified dry material and the solid plant asphalt are mixed in a mass ratio of 100:28, and then pulverized to obtain carbonized modified powder, wherein the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

[0071] S07. The carbonized modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:10:40, and then kneaded at 100°C for 30 minutes. The mixture is then extruded into 4mm strips and dried on a mesh belt at 150-160°C until the moisture content is below 10%, thus obtaining the carbonized modified molding material.

[0072] S08. The carbonized modified molding material is fed into a rotary kiln for carbon activation at a temperature of 500-950℃. It is first subjected to oxygen-deficient (oxygen content less than 1%) deep carbonization at a temperature of 500℃ for 2 hours to achieve preliminary pore expansion. Then, it is subjected to oxygen-deficient (oxygen content less than 1%) activation at a temperature of 950℃ with the addition of water vapor for 1 hour to achieve deep pore expansion, and finally, high ignition point columnar activated carbon is obtained. Among them, the wood gas obtained in S02 is used as one of the heating fuels in the rotary kiln for carbon activation.

[0073] Comparative Example 1

[0074] This comparative example describes a method for producing high ignition point plant-based columnar activated carbon, which includes the following steps:

[0075] S01. Agricultural and forestry residues (a mixture of wood chips, bamboo chips, fruit shells, coconut shells, etc.) are initially screened and dried to a moisture content of less than 15%. Then, they are carbonized in an oxygen-deficient environment at 500°C with an oxygen content of less than 1% to obtain carbonized material and carbonized flue gas. The carbonized flue gas is indirectly condensed and recovered to obtain bio-oil and wood gas. The carbonized material is cooled, crushed, and screened to obtain biochar powder. The carbonized material is crushed by roller crushing and then screened through a 30-mesh sieve.

[0076] S03. The bio-oil is first fractionated at 170-175℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 250-280℃, and the resulting gas is condensed in an indirect heat exchange stirred tank to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt.

[0077] S04. The biochar powder and the solid plant asphalt are mixed in a mass ratio of 100:28, and then pulverized to obtain carbonized modified powder, wherein the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

[0078] S07. The biochar modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:10:40, and then kneaded at 100°C for 30 minutes. The mixture is then extruded into 4mm strips and dried on a mesh belt at 150-160°C until the moisture content is below 10%, thus obtaining the carbonized modified molding material.

[0079] S08. The carbonized briquettes are fed into a rotary kiln for carbon activation at a temperature of 500-950℃. First, they are subjected to oxygen-deficient (oxygen content less than 1%) deep carbonization at a temperature of 500℃ for 2 hours to achieve preliminary pore expansion. Then, they are subjected to oxygen-deficient (oxygen content less than 1%) activation at a temperature of 950℃ with the addition of steam for 1 hour to achieve deep pore expansion, finally producing columnar activated carbon with a high ignition point. Among them, the wood gas obtained in S02 is used as one of the heating fuels in the rotary kiln for carbon activation.

[0080] Comparative Test

[0081] According to the test methods for determining carbon tetrachloride adsorption rate (activity) of wood-based activated carbon (GB / T 12496.1-1999), apparent density (GB / T 12496.1-1999), ash content (GB / T 12496.1-1999), ignition point test method for activated carbon (GB / T 20450-2006), and strength test method for coal-based granular activated carbon (GB / T 7702.3-2008), the high ignition point columnar activated carbons prepared in Examples 1, 2, and 3 were subjected to carbon tetrachloride adsorption tests, particle strength tests, ash content tests, ignition point tests, and bulk density tests. The results are as follows:

[0082]

[0083] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for producing high ignition point plant-based columnar activated carbon, characterized in that, It includes the following steps: S01. After initial screening and drying of agricultural and forestry residues to a moisture content of less than 15%, iron is removed to obtain biomass raw materials; wherein, the agricultural and forestry residues are a mixture of one or more of sawdust, bamboo shavings, fruit shells, and coconut shells. S02. The biomass raw material is carbonized in an oxygen-deficient environment of 350-800 ℃ to obtain carbonized material and carbonized flue gas. The carbonized flue gas is recovered by indirect stepwise condensation to obtain bio-oil. The carbonized material is cooled, crushed and screened to obtain biochar powder. S03. The bio-oil is first fractionated at 160-180 ℃, and the resulting gas is condensed to obtain light oil. The remaining liquid oil after the first fractionation is then fractionated at 180-300 ℃, and the resulting gas is condensed to obtain heavy oil. Finally, the remaining liquid oil after the second fractionation is condensed to room temperature to obtain solid plant asphalt. S04. The biochar powder, light oil and hot water are added to a mixing tank in a mass ratio of 100:1 to 5:1000 to 1500 and stirred. The pH of the mixture is adjusted to neutral using a 1% to 10% acid solution to obtain a carbonized modified slurry. S05. The carbonized modified slurry is dehydrated using a filter. After dehydration, it is washed evenly with hot water in the filter in a countercurrent manner, then filtered, dehydrated, and dried by airflow to obtain carbonized modified dry material. S06. The carbonized modified dry material and the solid plant asphalt are mixed in a mass ratio of 100:20-30, and then pulverized to obtain carbonized modified powder. S07. The carbonized modified powder, the heavy oil, and hot water are mixed in a mass ratio of 100:10-15:35-40, and then kneaded by heating at 70-100 ℃, extruded into strips of 3-6 mm specifications, and then dried by mesh belt at 100-160 ℃ until the moisture content is within 10% to obtain the carbonized modified molding material. S08. The carbonized modified molding material is put into a rotary furnace with carbon activation at a temperature of 500-950 ℃. First, it is subjected to oxygen-deficient deep carbonization at a temperature range of 500-850 ℃ for 1-3 hours to achieve preliminary pore expansion. Then, it is subjected to oxygen-deficient activation at a temperature range of 850-950 ℃ with the addition of water vapor for 1-4 hours to achieve deep pore expansion. Finally, high ignition point columnar activated carbon is obtained.

2. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S01, after iron removal, the agricultural and forestry residues are further processed by crushing and hot pressing. In S02, the carbonized flue gas is indirectly condensed in stages to obtain wood gas, which is used as one of the heating fuels in the carbon activation rotary kiln in S08.

3. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S02, the carbonization temperature is 350~800℃, and the oxygen content in the carbonization atmosphere is less than 1%. The obtained carbonization flue gas is indirectly condensed and the bio-oil is recovered. At the same time, wood gas is obtained and used for activation heating in S08. The carbonized material is crushed by roller crushing and then passed through a 30-mesh sieve.

4. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S03, bio-oil fractionation adopts two-stage temperature-controlled fractionation. The temperature range of the first-stage fractionation is 160-180℃, and the temperature range of the second-stage fractionation is 180-300℃. The gas after fractionation is condensed in a stirred tank with indirect heat exchange.

5. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S04, the acid solution is either hydrochloric acid or sulfuric acid; In S05, the carbonized modified slurry is filtered and washed simultaneously using a filter press. The washing process uses hot water at 50–80 °C for countercurrent washing.

6. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S06, the particle size of the carbonized modified powder obtained after pulverization is less than 200 mesh.

7. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S07, the heating and kneading time is 30 to 60 minutes, and the kneading temperature is 70 to 100℃.

8. The method for producing high ignition point plant-based columnar activated carbon as described in claim 1, characterized in that, In S08, the oxygen content of the carbon activation atmosphere in the integrated carbon activation rotary furnace is less than 1%.

9. A high ignition point plant-based columnar activated carbon, characterized in that, It is produced by the production method described in any one of claims 1 to 8.

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