Desulfurization and denitrification columnar activated carbon prepared from fibrous plant raw materials and preparation method of desulfurization and denitrification columnar activated carbon

Abstract

The preparation method comprises the following steps: shredding a light fibrous plant raw material which is difficult to process to 1-5mm, adding a certain amount of lignin, fully mixing with diammonium hydrogen phosphate or ammonium dihydrogen phosphate, carrying out hot press molding at 130-190 DEG C by using a pelletizer to prepare heavy particles with the particle size of 8-10mm, and carrying out high-temperature sintering to obtain the columnar activated carbon for desulfurization and denitrification of the fibrous plant raw material, thereby obtaining the columnar activated carbon for desulfurization and denitrification of the fibrous plant raw material and the columnar activated carbon for desulfurization and denitrification of the fibrous plant raw material. Heating the heavy particles to 400-700 DEG C in a rotary furnace, carbonizing for 1-3 hours, introducing a mixed gas of water vapor and air, and carrying out segmented activation at 850-950 DEG C-1000 DEG C to prepare high-quality activated carbon with the iodine value of more than or equal to 950 mg / g; crushing activated carbon to 140-325 meshes, mixing the crushed activated carbon with the composite glue solution, adding a proper amount of water for kneading, and forming the mixture into 2-8mm columnar particles by a hydraulic granulator or a screw extrusion granulator; through drying at the temperature of 100-300 DEG C and heat treatment at the temperature of 700-900 DEG C in a nitrogen, water vapor or anaerobic atmosphere, a basic group generated by the binder in the heat treatment has a very strong chemical adsorption effect on acid gas, later-stage modification is not needed, and excellent desulfurization and denitrification performance is achieved.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a desulfurization and denitrification columnar activated carbon made from fibrous plant materials and its preparation method. Background Technology

[0002] Fiberous plant materials such as hemp fiber, palm fiber, corn husk, cottonseed hulls, and coconut fiber, due to their fine filamentous structure and low density, have a large volume for the same weight in the industrial production of activated carbon, making them difficult to transport. Furthermore, during the carbonization and activation process in the rotary kiln, they are easily carried into the exhaust gas system by activation gases, fuel gas, and other gases generated during the process, hindering normal production. These types of raw materials are only used in activated carbon experiments in university laboratories and cannot be used in activated carbon factories.

[0003] Columnar activated carbon is formed by adding a binder to powdered activated carbon as the base carbon. Two common binders are used: one is organic binders such as CMC, but this process results in columnar activated carbon that is not resistant to high temperatures or acids and alkalis. The other is inorganic binders such as clay, but this process results in columnar activated carbon with high ash content and low adsorption capacity.

[0004] Common desulfurization and denitrification columnar activated carbon is mostly produced by physical methods. It is obtained by adding active substances such as potassium hydroxide in the later stage and then drying it. The process is complicated and costly. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a desulfurization and denitrification columnar activated carbon made from fibrous plant materials and its preparation method.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant materials, comprising:

[0008] The fibrous plant material is shredded to a length of 1mm to 5mm, and the moisture content is adjusted to 15% to 25%. 5% to 15% of lignin and 1% to 3% of diammonium hydrogen phosphate or diammonium dihydrogen phosphate are added to the fibrous plant material and mixed thoroughly. The mixture is then hot-pressed at 130 to 190℃ using a granulator to produce heavy granules of 8mm to 10mm.

[0009] Heavy granules are placed in a rotary kiln and carbonized at 400℃~700℃ for 1h~3h under a nitrogen atmosphere. Then, a mixture of water vapor and air is introduced, and the oxygen content is controlled to be ≤15%. The temperature is raised to 850℃→950℃→1000℃ for segmented activation, and each segment is held for 15min~30min to obtain activated carbon with an iodine value ≥950mg / g.

[0010] Activated carbon is crushed to 140-325 mesh and mixed with a composite adhesive solution containing 60%-140% of the dry weight of activated carbon. An appropriate amount of water is added and kneaded. The composite adhesive solution is prepared by mixing sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water in a mass ratio of 1:0.05-0.2:0.01-0.02:1. The mixture is then formed into columnar granules with a diameter of 2mm-8mm by a hydraulic granulator or screw extrusion granulator.

[0011] The columnar granules are dried in a rotary kiln at 100℃~300℃ until the moisture content is ≤6%, and the material layer thickness is maintained at more than 20cm. Then, they are heat-treated at 700℃~900℃ for 0.5h~2h in a nitrogen, water vapor or oxygen-free atmosphere to obtain desulfurization and denitrification columnar activated carbon containing alkaline groups.

[0012] In some embodiments, fibrous plant materials include hemp fiber, palm fiber, corn wool, cottonseed hulls, and coconut fiber.

[0013] In some embodiments, the columnar particles are subjected to surface rounding treatment before drying to control the aspect ratio of the particles to 1.2 to 2.5.

[0014] In some embodiments, the composite adhesive is prepared by mixing sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water, and stirring at a temperature of 50°C to 80°C for 0.5 to 1 hour.

[0015] In some embodiments, the heat treatment stage employs programmed temperature rise, including:

[0016] First, heat to 500℃, hold for 30 minutes, and then heat to the preset target temperature.

[0017] In some embodiments, the heat treatment is carried out in a nitrogen, water vapor, or oxygen-free atmosphere.

[0018] In a second aspect, the present invention also provides a columnar activated carbon for desulfurization and denitrification from fibrous plant material, wherein the activated carbon is prepared by the preparation method described in the first aspect.

[0019] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0020] The above technical solution involves cutting lightweight, difficult-to-process fibrous plant materials into 1mm-5mm shreds, then thoroughly mixing them with 5%-15% lignin (by dry weight of the fibrous plant materials) and 1%-3% diammonium hydrogen phosphate or ammonium dihydrogen phosphate. The mixture is then hot-pressed at 130-190℃ using a granulator to produce heavy granules of 8mm-10mm. This solves the problems of difficult transportation of fibrous raw materials in industrial production and the ease with which they are carried into the tail gas system by gases from the converter during the carbonization and activation processes. After carbonization in a rotary kiln at 400℃-700℃ for 1-3 hours, with the oxygen content controlled to ≤15%, the granules undergo segmented activation at 850℃→950℃→1000℃ to obtain iodine values ​​≥9. High-quality activated carbon with a concentration of 50 mg / g is prepared by crushing the activated carbon to 140-325 mesh and mixing it with a composite adhesive solution (sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water in a mass ratio of 1:0.05-0.2:0.01-0.02:1). A suitable amount of water is added and the mixture is kneaded. The resulting granules are then formed into 2-8 mm columnar particles using a hydraulic granulator or screw extruder. Finally, the granules are dried at 100-300℃ and heat-treated at 700-900℃ in a nitrogen, steam, or oxygen-free atmosphere to obtain columnar activated carbon containing alkaline groups. This activated carbon forms alkaline active sites during the preparation process, requiring no subsequent modification and exhibiting excellent desulfurization and denitrification performance. Detailed Implementation

[0021] 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.

[0022] In a first aspect, the present invention provides a method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant materials, comprising:

[0023] The fibrous plant material is shredded to a length of 1mm to 5mm, and the moisture content is adjusted to 15% to 25%. 5% to 15% of lignin and 1% to 3% of diammonium hydrogen phosphate or diammonium dihydrogen phosphate are added to the fibrous plant material and mixed thoroughly. The mixture is then hot-pressed at 130 to 190℃ using a granulator to produce heavy granules of 8mm to 10mm.

[0024] Heavy granules are placed in a rotary kiln and carbonized at 400℃~700℃ for 1h~3h under a nitrogen atmosphere. Then, a mixture of water vapor and air is introduced, and the oxygen content is controlled to be ≤15%. The temperature is raised to 850℃→950℃→1000℃ for segmented activation, and each segment is held for 15min~30min to obtain activated carbon with an iodine value ≥950mg / g.

[0025] Activated carbon is crushed to 140-325 mesh and mixed with a composite adhesive solution containing 60%-140% of the dry weight of activated carbon. An appropriate amount of water is added and kneaded. The composite adhesive solution is prepared by mixing sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water in a mass ratio of 1:0.05-0.2:0.01-0.02:1. The mixture is then formed into columnar granules with a diameter of 2mm-8mm by a hydraulic granulator or screw extrusion granulator.

[0026] The columnar granules are dried in a rotary kiln at 100℃~300℃ until the moisture content is ≤6%, and the material layer thickness is maintained at more than 20cm. Then, they are heat-treated at 700℃~900℃ for 0.5h~2h in a nitrogen, water vapor or oxygen-free atmosphere to obtain desulfurization and denitrification columnar activated carbon containing alkaline groups.

[0027] In this embodiment, fibrous plant material is shredded and then 5%–15% lignin is added as an auxiliary binder. The mixture is then hot-pressed in a granulator at 130–190°C to form heavy granules of 8 mm–10 mm. This temperature range ensures that the lignin naturally present in the plant material and the added lignin soften and bind together, while also preventing premature decomposition of diammonium hydrogen phosphate or diammonium dihydrogen phosphate. The added lignin improves the strength and granulation smoothness of the heavy granules.

[0028] The composite adhesive consists of sodium humate, a thermosetting water-soluble resin, and sodium carboxymethyl cellulose.

[0029] Prepare the mixture with a mass ratio of 1:0.05~0.2:0.01~0.02:1, and stir at 50℃~80℃ for 0.5~1h to ensure that all components are fully dissolved and compounded. This ratio ensures that the adhesive has suitable bonding properties and rheological characteristics, effectively bonding activated carbon particles without completely blocking their pore structure.

[0030] Cylindrical granules with a diameter of 2mm to 8mm are produced using a hydraulic granulator or a screw extruder. Surface rounding treatment controls the aspect ratio of the granules to 1.2 to 2.5, and this regular shape is beneficial for subsequent filling applications.

[0031] The segmented activation process (850℃→950℃→1000℃) combined with a holding time of 15min to 30min for each segment can gradually expand the pores without destroying the carbon skeleton structure, thus obtaining high-quality activated carbon with an iodine value ≥950mg / g.

[0032] After drying at 100℃~300℃ until the moisture content is ≤6%, heat treatment is performed. A programmed temperature rise process (first heating to 500℃ and holding for 30 minutes, then heating to 700℃~900℃) ensures stable formation of alkaline groups and curing of the binder. Heat treatment in a nitrogen, steam, or oxygen-free atmosphere prevents oxidation and burn-off of the activated carbon.

[0033] In this embodiment, the addition of diammonium hydrogen phosphate or diammonium dihydrogen phosphate corresponds to the subsequent decomposition and solidification of sodium humate during heat treatment, thereby constructing abundant alkaline groups on the surface of activated carbon, giving it both physical and chemical adsorption capabilities, and demonstrating excellent performance in desulfurization and denitrification applications.

[0034] In some embodiments, fibrous plant materials include hemp fiber, palm fiber, corn wool, cottonseed hulls, and coconut fiber.

[0035] In this embodiment, fibrous plant materials (including hemp fiber, palm fiber, corn fuzz, cottonseed hulls, or coconut fiber) are shredded, and a small amount of lignin is added before being granulated and compacted to produce heavy granules. This facilitates transportation by conveying equipment during the production process and enables the use of rotary kilns for carbonization and activation in the factory. Further carbonization of the heavy granules can increase the specific gravity of the carbonized material to a limited extent, thereby improving the strength of the later-bonded columnar granules.

[0036] In some embodiments, the oxygen content of the mixture of water vapor and air does not exceed 15%.

[0037] In some embodiments, the columnar particles are subjected to surface rounding treatment before drying to control the aspect ratio of the particles to 1.2 to 2.5.

[0038] In some embodiments, the composite adhesive is prepared by mixing sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water, and stirring at a temperature of 50°C to 80°C for 0.5 to 1 hour.

[0039] In some embodiments, the heat treatment stage employs programmed temperature rise, including:

[0040] First, heat to 500℃, hold for 30 minutes, and then heat to the preset target temperature.

[0041] In some embodiments, the heat treatment is carried out in a nitrogen, water vapor, or oxygen-free atmosphere.

[0042] In a second aspect, this embodiment also provides a desulfurization and denitrification columnar activated carbon made from fibrous plant material, which is prepared by the preparation method described in the first aspect.

[0043] To facilitate understanding, the following examples are provided:

[0044] A method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials includes the following steps:

[0045] (1) After cutting the fibrous plant material into shreds, adjust the moisture content to 15% to 25%, add a small amount of lignin and 1% to 3% of diammonium hydrogen phosphate or diammonium dihydrogen phosphate, and use the heating and crushing of the granulator to soften the lignin and make heavy granules with a diameter of 8mm to 10mm.

[0046] (2) The obtained particles are carbonized in a rotary kiln and activated at high temperature in a steam and air atmosphere to produce activated carbon.

[0047] (3) Preparation of composite adhesive: 1 part sodium humate, 0.05-0.2 parts thermosetting water-soluble resin, 0.01-0.02 parts sodium carboxymethyl cellulose are added to 1 part water and stirred at 50℃-80℃ for 0.5-1h to obtain composite adhesive.

[0048] (3) After the activated carbon is pulverized, a composite adhesive solution is added, along with an appropriate amount of water. The mixture is kneaded at 50℃~60℃ and then granulated into columnar particles of 2mm~8mm using a granulator.

[0049] (4) The columnar particles are dried in a rotary kiln, and during the rotation of the rotary kiln, the material is turned into short particles of dried material through tumbling and compression. The dried material is then heat-treated at high temperature in a nitrogen, steam or oxygen-free atmosphere to obtain columnar activated carbon.

[0050] The fibrous plant material mentioned in step (1) can be hemp fiber, palm fiber, corn wool, cottonseed hulls, coconut fiber, etc., and the amount of lignin added is 5% to 15% of the dry weight of the plant material.

[0051] The carbonization heating time in step (2) is 1-3 hours, the carbonization temperature is 400℃-700℃, and the holding time is 10-60 minutes. The activation temperature is 850℃-1000℃, and the activation is carried out until the iodine value of the activated carbon is ≥950mg / g.

[0052] The amount of composite adhesive solution added in step (3) is 60% to 140% of the dry weight of activated carbon.

[0053] The rotary kiln drying temperature in step (4) is 100℃~300℃, the material layer thickness is ≥20cm, and the moisture content is ≤6%. The high-temperature heat treatment temperature is 700℃~900℃, and the time is 0.5h~2h.

[0054] The above examples have the following advantages:

[0055] (1) After fibrous plant raw materials are shredded, a small amount of lignin is added and the granulation process is heated and crushed to produce heavy granules with high compressive strength. This facilitates transportation by conveying equipment during the production process and can meet the anti-crushing requirements in the carbonization and activation processes. Carbonization of heavy granules can effectively increase the specific gravity of carbonized materials, thereby improving the strength of the later-stage bonded columnar granules.

[0056] (2) Using self-made composite adhesive as a binder and high-temperature heat treatment, the resulting column carbon is resistant to high temperature and acid and alkali. Various additives play a synergistic role in increasing the strength and adsorption performance of the finished activated carbon.

[0057] (3) The basic groups generated by the binder during heat treatment do not require additional basic groups. These basic groups have a strong chemical adsorption effect on acidic substances and can be applied in the field of desulfurization and denitrification.

[0058] The above technical solution involves cutting lightweight, difficult-to-process fibrous plant materials into 1mm-5mm shreds, then thoroughly mixing them with 5%-15% lignin (by dry weight of the fibrous plant materials) and 1%-3% diammonium hydrogen phosphate or ammonium dihydrogen phosphate. The mixture is then hot-pressed at 130℃-190℃ using a granulator to produce heavy granules of 8mm-10mm. This solves the problems of difficult transportation of fibrous raw materials in industrial production and the ease with which they are carried into the tail gas system by gases from the rotary kiln during the carbonization and activation processes. After carbonization in the rotary kiln at 400℃-700℃ for 1-3 hours, a mixture of water vapor and air with an oxygen content ≤15% is introduced, followed by staged activation at 850℃→950℃→1000℃. High-quality activated carbon with an iodine value ≥950mg / g was prepared. The activated carbon was crushed to 140-325 mesh and mixed with a composite adhesive solution (sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water in a mass ratio of 1:0.05-0.2:0.01-0.02:1). An appropriate amount of water was added and kneaded. The mixture was then formed into columnar particles of 2mm-8mm using a hydraulic granulator or screw extruder. Finally, the particles were dried at 100℃-300℃ and heat-treated at 700℃-900℃ in a nitrogen, steam, or oxygen-free atmosphere to obtain columnar activated carbon containing alkaline groups. This activated carbon forms alkaline active sites during the preparation process and does not require subsequent modification, exhibiting excellent desulfurization and denitrification performance.

[0059] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0060] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods of various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials, characterized in that, include: The fibrous plant material is shredded to a length of 1mm to 5mm, and the moisture content is adjusted to 15% to 25%. 5% to 15% of lignin and 1% to 3% of diammonium hydrogen phosphate or diammonium dihydrogen phosphate are added to the fibrous plant material and mixed thoroughly. The mixture is then hot-pressed at 130 to 190℃ using a granulator to produce heavy granules of 8mm to 10mm. Heavy granules are placed in a rotary kiln and carbonized at 400℃~700℃ for 1h~3h under a nitrogen atmosphere. Then, a mixture of water vapor and air is introduced, and the oxygen content is controlled to be ≤15%. The temperature is raised to 850℃→950℃→1000℃ for segmented activation, and each segment is held for 15min~30min to obtain activated carbon with an iodine value ≥950mg / g. Activated carbon is crushed to 140-325 mesh and mixed with a composite adhesive solution containing 60%-140% of the dry weight of activated carbon. An appropriate amount of water is added and kneaded. The composite adhesive solution is prepared by mixing sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water in a mass ratio of 1:0.05-0.2:0.01-0.02:

1. The mixture is then formed into columnar granules with a diameter of 2mm-8mm by a hydraulic granulator or screw extrusion granulator. The columnar granules are dried in a rotary kiln at 100℃~300℃ until the moisture content is ≤6%, and the material layer thickness is maintained at more than 20cm. Then, they are heat-treated at 700℃~900℃ for 0.5h~2h in a nitrogen, water vapor or oxygen-free atmosphere to obtain desulfurization and denitrification columnar activated carbon containing alkaline groups.

2. The method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials according to claim 1, characterized in that, The fibrous plant materials include hemp fiber, palm fiber, corn fuzz, cottonseed hulls, and coconut fiber.

3. The method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials according to claim 1, characterized in that, The columnar particles are rounded before drying to control the aspect ratio of the particles to 1.2 to 2.

5.

4. The method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials according to claim 1, characterized in that, The composite adhesive is prepared by mixing sodium humate, thermosetting water-soluble resin, sodium carboxymethyl cellulose, and water, and stirring at a temperature of 50℃~80℃ for 0.5~1h.

5. The method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials according to claim 1, characterized in that, The heat treatment stage employs programmed temperature rise, including: First, heat to 500℃, hold for 30 minutes, and then heat to the preset target temperature.

6. The method for preparing desulfurization and denitrification columnar activated carbon from fibrous plant raw materials according to claim 1, characterized in that, The heat treatment is carried out in a nitrogen, water vapor, or oxygen-free atmosphere.

7. A columnar activated carbon for desulfurization and denitrification from fibrous plant raw materials, characterized in that, The activated carbon is prepared by the preparation method according to any one of claims 1-7.