Composite binder, columnar activated carbon, and method for preparing the same

Abstract

The application provides a composite binder, a columnar activated carbon and a preparation method thereof. The composite binder comprises starch, sodium hydroxide and water. The composite binder of the application has simple components, low price and is easy to prepare, thus solving the problems of complex components and high production cost of the binder in the prior art.

Description

Technical Field

[0001] This invention relates to the field of activated carbon preparation, and more specifically, to composite binders, columnar activated carbon, and methods for their preparation. Background Technology

[0002] In the production of coal-based briquetted activated carbon, a large amount of carbonized powder is generated during the oxygen carbonization process due to collisions and friction between materials. This carbonized powder lacks binding properties, making it difficult to recycle and reuse for activated carbon production. Coupled with its low price, tendency to spontaneously combust, and difficulty in processing, carbonized powder has long been a pressing problem for activated carbon manufacturers. However, since carbonized powder is a product of briquetted materials undergoing oxidation and carbonization, it has low volatile content and a certain porous structure. By adding a binder and pressing it into strips, columnar activated carbon with stronger adsorption properties can be produced.

[0003] To date, no patent literature has studied the process of forming columnar activated carbon from carbonized powder during the preparation of coal-based activated carbon; only research on the formulation of briquette forming binders exists. Existing research on briquette forming binders involves 3 to 8 types of binders, and most binders are prepared through thermal processing. This not only increases production costs and technological complexity but also negatively impacts production equipment and environmental remediation. Summary of the Invention

[0004] The main objective of this invention is to provide composite binders, columnar activated carbon, and their preparation methods to solve the problems of complex composition, high production cost, and ineffective recycling of carbonized powder in existing technologies.

[0005] To achieve the above objectives, according to one aspect of the present invention, a composite adhesive is provided, comprising starch, sodium hydroxide and water.

[0006] Furthermore, in the composite binder, the weight ratio of starch, sodium hydroxide and water is (3-4):(0.2-0.3):(10-20).

[0007] Furthermore, the starch is selected from one or more of potato starch, corn starch, and sweet potato starch.

[0008] According to another aspect of the present invention, a method for preparing columnar activated carbon by forming carbonized powder is provided, comprising the following steps:

[0009] Step S1: Mix the carbonized powder with the residue from direct coal liquefaction, then grind them to obtain a mixed dry material;

[0010] Step S2: Mix the dry mixture with the above-mentioned composite adhesive to obtain the wet mixture;

[0011] Step S3: Extrude the mixed wet material into shape, dry it, and obtain the shaped carbon column;

[0012] Step S4: Activate the formed carbon column to obtain columnar activated carbon.

[0013] Furthermore, the ash content of the carbonized powder shall not exceed 3%, and the volatile matter shall not exceed 23%.

[0014] Furthermore, the weight ratio of carbonized powder to coal direct liquefaction residue is (80-90):(10-20).

[0015] Further, in step S1, the 325-mesh passing rate of the mixed dry material is 90-98%; preferably, the 325-mesh passing rate of the mixed dry material is 95%.

[0016] Further, in step S2, the mixing process includes: kneading the mixed dry material and the composite adhesive for 15 to 25 minutes at a temperature of room temperature.

[0017] Furthermore, in step S3, the extrusion molding pressure is 0.2–10 MPa.

[0018] Furthermore, in step S4, the activation process includes:

[0019] The shaped carbon column is heated to 880-900℃, and then an activating agent is introduced to carry out the activation reaction to obtain columnar activated carbon; preferably, the reaction temperature of the activation reaction is 900-920℃, and the reaction time is 2-3h; preferably, the heating rate during the heating process is not greater than 20℃ / min.

[0020] Preferably, the activator is water vapor; more preferably, the activation reaction is carried out in an activation furnace, where the flow rate of water vapor is 115-125 drops / minute and the rotation speed of the central shaft is 40-50 rpm.

[0021] According to another aspect of the present invention, columnar activated carbon is provided, which is prepared by the method described above.

[0022] The present invention utilizes starch, sodium hydroxide, and water as a composite binder for preparing columnar activated carbon. This method is simple in composition, inexpensive, and easy to prepare, thus solving the problems of complex binder composition and high production costs in existing technologies. Simultaneously, the sodium hydroxide in the water provides an alkaline environment that promotes starch denaturation, transforming it into a viscous paste-like solution, thereby giving the composite binder provided by the present invention excellent binding properties. Carbonized powder, being a product of oxidization and carbonization of briquettes, possesses a porous structure and thus holds promise for applications in adsorption. However, carbonized powder lacks binding properties, making it difficult to recycle and prepare activated carbon. Based on the superior properties of the composite binder provided by the present invention, its application in pressing carbonized powder into columnar activated carbon can produce columnar activated carbon while also giving it excellent roller strength, achieving more effective recycling of carbonized powder. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0024] To address the problems in the prior art as described above, according to one aspect, the present invention provides a composite binder comprising starch, sodium hydroxide, and water. Using starch, sodium hydroxide, and water as the composite binder for preparing columnar activated carbon results in a simple composition, low cost, and ease of preparation, thus solving the problems of complex composition and high production costs in the prior art. Simultaneously, the sodium hydroxide in the water provides an alkaline environment that promotes starch denaturation, transforming it into a viscous paste-like solution, thereby giving the composite binder provided by the present invention excellent binding properties. Carbonized powder, being a product of oxidization and carbonization of briquettes, possesses a porous structure and thus holds promise for application in the adsorption field. However, carbonized powder lacks binding properties, making it difficult to recycle and prepare activated carbon. Based on the superior properties of the composite binder provided by the present invention, its application in the compression molding of carbonized powder can produce columnar activated carbon, while also giving it excellent roller strength, achieving more effective recycling of carbonized powder.

[0025] To further improve the bonding performance of the composite adhesive, in a preferred embodiment, the weight ratio of starch, sodium hydroxide, and water in the composite adhesive is (3-4):(0.2-0.3):(10-20). This preferred ratio better promotes starch gelatinization, allowing the composite adhesive to exhibit good adhesion over a wider temperature range, further simplifying the preparation process and reducing its production cost.

[0026] The type of starch can be conventional in the art, but for the purpose of further reducing production costs and improving the bonding performance of the composite adhesive, the starch is preferably selected from one or more of potato starch, corn starch, and sweet potato starch.

[0027] Preferably, the water is distilled water.

[0028] In practical operation, preferably, the above-mentioned composite adhesive can be prepared by the following method: Step a, mixing the first part of water and starch and stirring until there is no layering phenomenon to obtain a starch solution; Step b, mixing the second part of water and sodium hydroxide and stirring until the sodium hydroxide dissolves to obtain a sodium hydroxide solution; Step c, stirring the starch solution and the sodium hydroxide solution at room temperature for 1 to 3 minutes to obtain the composite adhesive.

[0029] According to another aspect of the present invention, a method for preparing columnar activated carbon by molding carbonized powder is also provided. The method includes the following steps: Step S1: mixing carbonized powder with coal direct liquefaction residue, and then grinding to obtain a mixed dry material; Step S2: mixing the mixed dry material with the above-mentioned composite binder to obtain a mixed wet material; Step S3: extruding the mixed wet material into shape, drying to obtain a shaped carbon column; Step S4: activating the shaped carbon column to obtain columnar activated carbon. This method uses starch, sodium hydroxide, and water as a composite binder for preparing columnar activated carbon. Its composition is simple, inexpensive, and easy to prepare, thus solving the problems of complex binder composition and high production cost in the prior art. At the same time, sodium hydroxide in the water provides an alkaline environment, which can promote starch denaturation, making it a viscous paste solution, thereby giving the composite binder provided by the present invention excellent bonding performance. Carbonized powder, as a product of oxidization and carbonization of briquetted material, has a porous structure and therefore has the potential for application in the adsorption field. However, carbonized powder lacks binding properties, making it difficult to recycle and prepare activated carbon. The composite binder provided by this invention is applied to carbonized powder, and then pressed into strips to prepare columnar activated carbon, which exhibits excellent roller strength. Coal direct liquefaction residue is a substance with extremely high carbon content, containing unconverted coal organic matter, conversion intermediates, inorganic minerals, and added liquefaction catalysts from the liquefaction raw materials. When used in conjunction with the carbonized powder of this invention, the numerous carbon-rich n-alkane branches in the coal direct liquefaction residue can form a stable carbon skeleton with the carbon atoms in the carbonized powder, facilitating polymerization or cross-linking reactions. This not only increases the hot strength of the product but also increases the number of micropores in the activated carbon product, improving its adsorption performance. The columnar activated carbon produced according to this invention has an iodine value >1100 mg / g, a carbon tetrachloride adsorption rate >60%, and maintains a strength >92% and ash content <13%.

[0030] To further improve the adsorption performance of columnar activated carbon, preferably, the ash content of the carbonized powder is no more than 3%, and the volatile matter content is no more than 23%. Carbonized powder with lower ash and volatile matter content is more conducive to preparing activated carbon with high adsorption performance.

[0031] To further enhance the overall performance of columnar activated carbon, in a preferred embodiment, the weight ratio of carbonized powder to direct coal liquefaction residue is (80-90):(10-20), for example, 85:15. This preferred weight ratio facilitates the further development of micropores in the formed carbon column during the activation reaction process, thereby increasing the iodine adsorption value and adsorption rate of the product. Simultaneously, this preferred weight ratio also enhances the cold strength of the formed carbon column, making it more suitable for industrial production requirements.

[0032] To further improve the efficiency of the activation reaction and to ensure more thorough mixing of the dry mixture and the composite binder in subsequent steps, in a preferred embodiment, the 325-mesh pass rate of the dry mixture in step S1 is 90-98%; preferably, the 325-mesh pass rate is 95%. In actual operation, preferably, the dry mixture is screened through a 325-mesh Taylor standard sieve.

[0033] To ensure a more uniform mixing of the dry mixture and the composite adhesive, in a preferred embodiment, step S2 includes kneading the dry mixture and the composite adhesive for 15-25 minutes at room temperature. Preferably, the kneading process is performed in a kneader.

[0034] To ensure that the columnar activated carbon possesses both high mechanical and adsorption properties, in a preferred embodiment, the extrusion molding pressure in step S3 is 0.2–10 MPa. Extrusion molding under this pressure yields columnar activated carbon that balances good roller strength, bulk density, and adsorption performance.

[0035] Preferably, in step S3, the drying conditions are room temperature and 1 to 3 days.

[0036] To further improve the adsorption performance of columnar activated carbon, in a preferred embodiment, step S4 includes the activation process comprising: heating the shaped carbon column to 880–900°C, and then introducing an activating agent to carry out an activation reaction to obtain columnar activated carbon; preferably, the reaction temperature of the activation reaction is 900–920°C, and the reaction time is 2–3 h; preferably, the heating rate during the heating process is not greater than 20°C / min; preferably, the activating agent is water vapor; more preferably, the activation reaction is carried out in an activation furnace, the flow rate of water vapor in the activation furnace is 115–125 drops / min, and the rotation speed of the central shaft is 40–50 rpm.

[0037] Preferably, the shaped charcoal column is cut into 1-2 cm charcoal strips before activation treatment; more preferably, in actual operation, the cutting method can be manual breaking.

[0038] According to another aspect of the present invention, columnar activated carbon is provided, which is prepared by the method described above. This columnar activated carbon uses starch, sodium hydroxide, and water as a composite binder for preparation. Its composition is simple, inexpensive, and easy to prepare, thus solving the problems of complex binder composition and high production costs in the prior art. Simultaneously, the sodium hydroxide in the water provides an alkaline environment, which promotes starch denaturation, making it a viscous paste solution, thereby giving the composite binder provided by the present invention excellent binding properties. Carbonized powder, being a product of oxidization and carbonization of briquettes, has a porous structure and therefore has potential for application in the adsorption field. However, carbonized powder lacks binding properties, making it difficult to recycle and prepare activated carbon. Applying the composite binder provided by the present invention to carbonized powder, followed by pressing into strips, yields columnar activated carbon with excellent roller strength. Coal direct liquefaction residue is a substance with extremely high carbon content, containing unconverted coal organic matter, conversion intermediates, inorganic minerals, and added liquefaction catalysts from the liquefaction feedstock. When used in conjunction with the carbonized powder of this invention, the numerous carbon-rich n-alkane branches in the coal direct liquefaction residue can form a stable carbon skeleton with the carbon atoms in the carbonized powder, which is conducive to polymerization or cross-linking reactions. This not only increases the hot strength of the product but also increases the number of micropores in the activated carbon product, thereby improving its adsorption performance. The columnar activated carbon produced according to this invention has an iodine value >1100 mg / g, a carbon tetrachloride adsorption rate >60%, and can guarantee a strength >92% and an ash content <13%.

[0039] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0040] Example 1:

[0041] 1. 1000g of carbonized powder produced during the production of activated carbon is mixed with 165g of coal direct liquefaction residue, and then ground to obtain a mixed dry material. The fineness of the powder reaches 325 mesh with a passing rate of more than 95%. The ash content of the carbonized powder is 2.1%, and the volatile matter is 19%.

[0042] 2. Weigh 100g of corn starch, add 300g of distilled water, and stir thoroughly until the starch and water do not separate into layers, thus obtaining a starch solution;

[0043] 3. Weigh 8g of sodium hydroxide solid, add 250g of distilled water, and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution;

[0044] 4. Add the sodium hydroxide solution obtained in step 3 to the starch solution obtained in step 2, and stir at room temperature for 3 minutes to obtain a composite adhesive;

[0045] 5. Add the dry mixture and composite binder to the kneader and mix thoroughly. Stir for 15 minutes at room temperature to obtain the wet mixture.

[0046] 6. Load the mixed wet material into the pressing machine, extrude it into shape under a pressure of 10 MPa, and then let it air dry at room temperature for 3 days to obtain the shaped carbon column;

[0047] 7. Break the shaped carbon column into carbon strips of about 1 cm, put them into a small experimental activation furnace, and activate them for 170 min at an experimental temperature of 920℃ and a distilled water flow rate of 120 drops / min to obtain columnar activated carbon.

[0048] Activated carbon test indicators: roller strength 92%, bulk density 328g / L, iodine adsorption value 1141mg / g, methylene blue adsorption value 250mg / g, carbon tetrachloride adsorption rate 69%.

[0049] Example 2:

[0050] The difference from Example 1 is that the amount of coal direct liquefaction residue used is 116g, and 50g of coal tar pitch is added, and the process is activated for 150min.

[0051] Activated carbon test indicators: drum strength 93%, bulk density 328g / L, iodine adsorption value 1129mg / g, methylene blue adsorption value 235mg / g, carbon tetrachloride adsorption rate 62%.

[0052] Comparative Example 1:

[0053] 1. 1000g of carbonized powder produced during the production of activated carbon is mixed with 165g of coal tar pitch and then ground to obtain a mixed dry material. The fineness of the powder reaches 325 mesh with a passing rate of more than 90%. The carbonized powder has an ash content of 2.1% and a volatile content of 19%. The coal tar pitch has an ash content of 0.32%, a volatile content of 50.35%, and a binding index of 91.

[0054] 2. Weigh 100g of corn starch, add 300g of distilled water, and stir thoroughly until the starch and water do not separate into layers, thus obtaining a starch solution;

[0055] 3. Weigh 8g of sodium hydroxide solid, add 250g of distilled water, and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution;

[0056] 4. Add the sodium hydroxide solution obtained in step 3 to the starch solution obtained in step 2, and stir at room temperature for 1 minute to obtain a composite adhesive;

[0057] 5. Add the dry mixture and composite binder to the kneader and mix thoroughly. Stir for 25 minutes at room temperature to obtain the wet mixture.

[0058] 6. Load the mixed wet material into the pressing machine, extrude it into shape under a pressure of 10 MPa, and then let it air dry at room temperature for 1 day to obtain the shaped carbon column;

[0059] 7. Break the shaped carbon column into carbon strips of about 1 cm, put them into a small experimental activation furnace, and activate them for 120 min at an experimental temperature of 920℃ and a distilled water flow rate of 120 drops / min to obtain columnar activated carbon.

[0060] Activated carbon test indicators: roller strength 94%, bulk density 365g / L, iodine adsorption value 990mg / g, methylene blue adsorption value 140mg / g, carbon tetrachloride adsorption rate 47%.

[0061] Comparative Example 2:

[0062] The difference from Comparative Example 1 is that the amount of coal tar pitch used is 50g.

[0063] Activated carbon testing indicators: roller strength 68%, bulk density 305g / L, iodine adsorption value 1291mg / g, methylene blue adsorption value 270mg / g.

[0064] Comparative Example 3:

[0065] The difference from Comparative Example 2 is that coal direct liquefaction residue was used instead of coal tar pitch.

[0066] Activated carbon testing indicators: roller strength 83%, bulk density 358g / L, iodine adsorption value 786mg / g, methylene blue adsorption value 100mg / g, carbon tetrachloride adsorption rate 30%.

[0067] Comparative Example 4:

[0068] The difference from Comparative Example 2 is that a different type of coal tar pitch was used, and the amount was 15%. The coal tar pitch used had an ash content of 2.64%, a volatile content of 37.31%, and a caking index of 98.

[0069] Activated carbon test indicators: drum strength 97%, bulk density 393g / L, iodine adsorption value 1090mg / g, methylene blue adsorption value 217mg / g, carbon tetrachloride adsorption rate 62%.

[0070] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0071] This invention uses starch, sodium hydroxide, and water as a composite binder for preparing columnar activated carbon. Its composition is simple, inexpensive, and easy to prepare, thus solving the problems of complex binder composition and high production costs in existing technologies. Simultaneously, the sodium hydroxide in the water provides an alkaline environment that promotes starch denaturation, turning it into a viscous paste solution, thereby giving the composite binder provided by this invention excellent binding properties. Carbonized powder, being a product of briquetting material undergoing oxidation and carbonization, possesses a porous structure and therefore shows promise for application in the adsorption field. However, carbonized powder lacks binding properties, making it difficult to recycle and prepare activated carbon. Applying the composite binder provided by this invention to carbonized powder, followed by compression molding, yields columnar activated carbon with excellent roller strength. Furthermore, coal direct liquefaction residue is a substance with extremely high carbon content, containing unconverted coal organic matter from the liquefaction feedstock, conversion intermediates, inorganic minerals, and added liquefaction catalysts. When used in conjunction with the carbonized powder of this invention, the large number of carbon atoms in the n-alkane branches contained in the coal direct liquefaction residue can form a stable carbon skeleton with the carbon atoms in the carbonized powder, which is conducive to polymerization or cross-linking reactions. This not only increases the hot strength of the product, but also increases the number of micropores in the activated carbon product and improves its adsorption performance.

[0072] In contrast, Comparative Examples 1 and 2 did not use, or used insufficient amounts of coal direct liquefaction residue, resulting in activated carbon with inferior performance compared to the present invention.

[0073] The columnar activated carbon produced according to the present invention has an iodine value >1100mg / g, a carbon tetrachloride adsorption rate >60%, and can guarantee a strength >92% and an ash content <13%.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing columnar activated carbon by molding carbonized powder, characterized in that, Includes the following steps: Step S1: Mix the carbonized powder with the residue from direct coal liquefaction, then grind them to obtain a mixed dry material; Step S2: Mix the dry mixture with the composite binder to obtain a wet mixture; Step S3: Extrude the mixed wet material into a molded shape and dry it to obtain a molded carbon column; Step S4: Activate the shaped carbon column to obtain columnar activated carbon; The composite binder comprises starch, sodium hydroxide, and water, wherein the weight ratio of starch, sodium hydroxide, and water is (3~4):(0.2~0.3):(10~20); the starch is selected from one or more of potato starch, corn starch, and sweet potato starch. The weight ratio of the carbonized powder to the coal direct liquefaction residue is (80~90):(10~20). The columnar activated carbon has an iodine value >1100 mg / g, a carbon tetrachloride adsorption rate >60%, a strength >92%, and an ash content <13%. In step S1, the 325-mesh passing rate of the mixed dry material is 90-98%. In step S2, the mixing process includes: kneading the mixed dry material and the composite adhesive, the kneading time being 15-25 minutes, and the kneading temperature being room temperature; In step S3, the extrusion molding pressure is 0.2~10MPa; In step S4, the activation process includes: heating the shaped carbon column to 880~900℃, and then introducing an activating agent to carry out an activation reaction to obtain the columnar activated carbon; the reaction temperature of the activation reaction is 900~920℃, and the reaction time is 2~3h; the activating agent is water vapor; the activation reaction is carried out in an activation furnace, and the flow rate of water vapor in the activation furnace is 115~125 drops / min, and the rotation speed of the central shaft is 40~50 rpm.

2. The method according to claim 1, characterized in that, The ash content of the carbonized powder is no higher than 3%, and the volatile matter content is no higher than 23%.

3. The method according to claim 1, characterized in that, In step S1, the 325-mesh pass rate of the mixed dry material is 95%.

4. The method according to claim 1, characterized in that, In step S4 The heating rate during the heating process shall not exceed 20℃ / min.

5. A columnar activated carbon, characterized in that, The columnar activated carbon is prepared by the method according to any one of claims 1 to 4.