Method for improving carbon dioxide adsorption performance of activated carbon

Abstract

The application discloses a method for improving carbon dioxide adsorption performance of activated carbon, and relates to the technical field of activated carbon preparation.The method comprises the following steps: obtaining initial activated carbon-based carbon; soaking the initial activated carbon-based carbon in a monovalent inorganic strong acid with a concentration of 3-7% for 7-9 hours to enhance the functional groups in the initial activated carbon-based carbon, and obtaining target activated carbon-based carbon; sequentially performing rinsing and drying on the target activated carbon-based carbon, and obtaining modified activated carbon; wherein raw coal is mixed and stirred in proportion to obtain a mixture; the mixture is added into an activated carbon forming machine to extrude the mixture, and columnar material is obtained; the columnar material is carbonized through a static temperature control carbonization technology, and carbonized material is obtained; in a high-temperature and anaerobic environment, the carbonized material is slowly activated by a mixed gas of carbon dioxide and water vapor for 2-3 hours, and initial activated carbon-based carbon is obtained. Through the method, the carbon dioxide adsorption performance of activated carbon can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of activated carbon preparation technology, and in particular to a method for improving the carbon dioxide adsorption performance of activated carbon. Background Technology

[0002] Carbon dioxide is the most common greenhouse gas and a crucial emission indicator in the environmental protection field. International climate conventions have set specific limits on carbon dioxide emissions for all countries. Current carbon dioxide recovery technologies typically include solvent absorption, pressure swing adsorption (PSA), membrane separation, and catalytic combustion. Among these, PSA, which utilizes activated carbon adsorption technology, is the most effective method for recovering and purifying carbon dioxide. It features simple processing, high recovery efficiency, and no secondary pollution, and enjoys broad market demand.

[0003] Among related technologies, the pressure swing adsorption (PSA) technology for recovering carbon dioxide uses activated carbon specifically designed for carbon dioxide adsorption. However, the adsorption capacity of this activated carbon is only about 50 ml / g, and the adsorption effect is still relatively poor. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a method for improving the carbon dioxide adsorption performance of activated carbon, which can effectively improve the adsorption performance of activated carbon for carbon dioxide.

[0005] This application provides a method for improving the carbon dioxide adsorption performance of activated carbon, including:

[0006] Obtain initial activated carbon-based carbon;

[0007] The initial activated carbon-based carbon is soaked in a monobasic inorganic strong acid with a concentration between 3% and 7% for 7 to 9 hours to enhance the functional groups in the initial activated carbon-based carbon, thereby obtaining the target activated carbon-based carbon; the target activated carbon-based carbon is then rinsed and dried sequentially to obtain modified activated carbon.

[0008] The process of obtaining the initial activated carbon-based carbon includes:

[0009] Obtain raw coal and mix it in a certain proportion to obtain a mixture;

[0010] The mixture is added to an activated carbon molding machine to extrude the mixture and obtain columnar material;

[0011] The columnar material is carbonized using static temperature-controlled carbonization technology to obtain carbonized material;

[0012] Under high temperature and oxygen-free environment, the carbonized material is slowly activated for 2 to 3 hours by a mixture of carbon dioxide and water vapor to obtain the initial activated carbon-based carbon.

[0013] According to some embodiments of this application, the monoprotic inorganic strong acid is nitric acid, and the initial activated carbon-based carbon is soaked in a monoprotic inorganic strong acid with a concentration between 3% and 7% for 7 to 9 hours to enhance the functional groups in the initial activated carbon-based carbon, thereby obtaining the target activated carbon-based carbon, comprising:

[0014] The initial activated carbon-based carbon was soaked in 5% nitric acid for 8 hours to enhance the functional groups in the initial activated carbon-based carbon, thereby obtaining the target activated carbon-based carbon.

[0015] According to some embodiments of this application, the raw material coal has the following raw material mass percentages: 25% to 30% Taixi coal powder, 5% to 10% coking coal powder, 5% to 15% tar, 15% to 25% auxiliary binder, and 30% to 40% bamboo charcoal powder.

[0016] According to some embodiments of this application, the mass percentage of the mixed gas of carbon dioxide and water vapor is 25% to 35% carbon dioxide and 65% to 75% water vapor.

[0017] According to some embodiments of this application, the Taixi coal powder is obtained by grinding Taixi coal after dry distillation at 580°C to 620°C for 50 to 70 minutes.

[0018] According to some embodiments of this application, the auxiliary binder is one of phenolic residue or lignin.

[0019] According to some embodiments of this application, after sequentially rinsing and drying the target activated carbon-based carbon to obtain modified activated carbon, the process includes:

[0020] The functional groups in the initial activated carbon-based carbon and the modified activated carbon are quantitatively detected to obtain the detection results of the first functional group corresponding to the initial activated carbon-based carbon and the detection results of the second functional group corresponding to the modified activated carbon.

[0021] The adsorption performance of the initial activated carbon-based carbon and the modified activated carbon on carbon dioxide was tested respectively to obtain a first adsorption performance test result corresponding to the initial activated carbon-based carbon and a second adsorption performance test result corresponding to the modified activated carbon.

[0022] The first functional group detection result and the second functional group detection result are compared to obtain the first comparison result;

[0023] The first adsorption performance test result and the second adsorption performance test result are compared to obtain a second comparison result;

[0024] Based on the first comparison result and the second comparison result, the effect of the number of functional groups on the carbon dioxide adsorption performance is determined.

[0025] The beneficial effects of this invention are reflected in the following: by obtaining initial activated carbon-based carbon, the initial activated carbon-based carbon is soaked in a monobasic inorganic strong acid with a concentration between 3% and 7% for 7 to 9 hours to enhance the functional groups in the initial activated carbon-based carbon, thereby obtaining the target activated carbon-based carbon. The initial activated carbon-based carbon is obtained through the following steps: obtaining raw coal and mixing and stirring the raw coal in a certain proportion to obtain a mixture; adding the mixture to an activated carbon forming machine to extrude the mixture to obtain columnar material; carbonizing the columnar material using static temperature-controlled carbonization technology to obtain carbonized material; and slowly activating the carbonized material for 2 to 3 hours in a high-temperature, oxygen-free environment using a mixture of carbon dioxide and water vapor to obtain the initial activated carbon-based carbon. This application, through this setup, uses a monobasic inorganic strong acid to impregnate the initial activated carbon-based carbon to enhance the functional groups in the initial activated carbon-based carbon, thereby improving the adsorption performance of carbon dioxide and enhancing the adsorption performance of modified activated carbon for carbon dioxide, which has a positive effect on environmental protection.

[0026] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0027] Additional aspects and advantages of this application will become apparent and readily understood in conjunction with the following description of the embodiments, in which:

[0028] Figure 1 A schematic flowchart illustrating a method for improving the carbon dioxide adsorption performance of activated carbon provided in an embodiment of this application;

[0029] Figure 2 A schematic diagram of the process for obtaining initial activated carbon-based carbon provided in an embodiment of this application;

[0030] Figure 3 A schematic diagram of the process for obtaining target activated carbon-based carbon provided in an embodiment of this application;

[0031] Figure 4 This is a flowchart illustrating the effect of the number of functional groups on carbon dioxide adsorption performance, provided as an embodiment of this application. Detailed Implementation

[0032] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0033] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0034] In the description of this application, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0035] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0036] Carbon dioxide is the most common greenhouse gas and a crucial emission indicator in the environmental protection field. International climate conventions have set specific limits on carbon dioxide emissions for all countries. Currently, China's carbon dioxide recovery and utilization technology is still in its early stages. Current carbon dioxide recovery technologies typically include solvent absorption, pressure swing adsorption (PSA), membrane separation, and catalytic combustion. However, PSA, which utilizes activated carbon adsorption technology, is the most effective method for recovering and purifying carbon dioxide. It features simple processing, high recovery efficiency, and no secondary pollution, and enjoys broad market demand.

[0037] Among related technologies, the pressure swing adsorption (PSA) technology for recovering carbon dioxide uses activated carbon specifically designed for carbon dioxide adsorption. However, the adsorption capacity of this activated carbon is only about 50 ml / g, and the adsorption effect is still relatively poor.

[0038] To address the aforementioned problems, this application proposes a method for improving the carbon dioxide adsorption performance of activated carbon. The embodiments of this application will be further described below with reference to the accompanying drawings.

[0039] This application provides a method for improving the carbon dioxide adsorption performance of activated carbon, such as... Figure 1 As shown, the method includes the following steps:

[0040] Step S100: Obtain initial activated carbon-based carbon;

[0041] Step S200: The initial activated carbon-based carbon is soaked in a monobasic inorganic strong acid with a concentration between 3% and 7% for 7h to 9h to enhance the functional groups in the initial activated carbon-based carbon and obtain the target activated carbon-based carbon.

[0042] In step S300, the target activated carbon-based carbon is rinsed and dried sequentially to obtain modified activated carbon.

[0043] Among them, reference Figure 2 Step 100 includes, but is not limited to, the following steps: Step S110, obtaining raw coal and mixing it in proportion to obtain a mixture; Step S120, adding the mixture to an activated carbon forming machine to extrude it to obtain columnar material; Step S130, carbonizing the columnar material using static temperature-controlled carbonization technology to obtain carbonized material; Step S140, under high temperature and oxygen-free environment, slowly activating the carbonized material for 2 to 3 hours using a mixture of carbon dioxide and water vapor to obtain initial activated carbon-based carbon.

[0044] It should be noted that the static temperature-controlled carbonization technology used in the carbonization process allows for more thorough separation of volatile organic compounds, thereby creating more porous structures, which is more conducive to activation, making the activated carbon more porous, and further improving its CO2 adsorption capacity.

[0045] It should be noted that the modified activated carbon is prepared by rinsing the activated carbon base carbon thoroughly and then drying it. This method of improving the carbon dioxide adsorption performance of activated carbon results in modified activated carbon with pore sizes between 0.5 nm and 1 nm, achieving a CO2 adsorption capacity of approximately 60 ml / g. This improves the adsorption performance of carbon dioxide, enhances the adsorption capacity of carbon dioxide-specific activated carbon, and has a positive effect on environmental protection.

[0046] It should be noted that, under certain conditions of activated carbon pore distribution, when the pore size of activated carbon is between 0.5 nm and 1 nm, it has a good adsorption capacity for CO2.

[0047] It should be noted that the target activated carbon base carbon is rinsed with water until it is nearly neutral, and then dried in an oven at 150±10℃ until constant weight to obtain modified activated carbon.

[0048] It should be noted that the target activated carbon-based carbon is oxidized by acid washing with a monobasic inorganic strong acid for 7 to 9 hours to increase or decrease the content of functional groups in the activated carbon and change its adsorption performance. Since carbon dioxide is the main cause of global warming, the modified activated carbon can effectively adsorb and remove carbon dioxide, which has a positive effect on environmental protection.

[0049] It should be noted that monoprotic inorganic strong acids include nitric acid and hydrochloric acid. Nitric acid is a strong acid with strong oxidizing and corrosive properties, and its chemical formula is HNO3. Hydrochloric acid is the common name for hydrochloric acid, which is an aqueous solution of hydrogen chloride (HCl) gas. The oxygen-containing functional groups of activated carbon are generally considered to mainly include eight types: carboxyl, acid anhydride, carbonyl, quinone, lactone, hydroxyl, ether, and phenolic hydroxyl.

[0050] Specifically, the total basicity, phenolic hydroxyl groups, lactone groups, and carboxyl groups of the initial activated carbon base, activated carbon obtained by impregnation with 5% HCl (hydrochloric acid, an aqueous solution of hydrogen chloride), activated carbon obtained by impregnation with 5% HNO3 (nitric acid), activated carbon obtained by impregnation with 5% H2O2 (hydrogen peroxide, an inorganic compound), activated carbon obtained by impregnation with 1% HNO3, activated carbon obtained by impregnation with 3% HNO3, and activated carbon obtained by impregnation with 7% HNO3 were measured. The results are shown in Table 1. The adsorption rates of the above base carbon and activated carbon for CCl4 (carbon tetrachloride, an organic compound), CO2 (carbon dioxide, a carbon oxide), and NH3 (ammonia, a nitrogen oxide) were measured. The results are shown in Table 2.

[0051] Table 1:

[0052] Initial activated carbon-based carbon 0.7787 0.992 0.0088 -0.0371 5% HCl 0.3183 0.1415 0.0140 0.0561 <![CDATA[5%HNO3]]> 0.2972 0.2695 0.0571 0.0462 <![CDATA[5%H2O2]]> 0.7617 0.1461 0.0143 -0.0078 <![CDATA[1%HNO3]]> 0.3972 0.1276 0.0105 0.0109 <![CDATA[3%HNO3]]> 0.3174 0.1926 0.0386 0.0328 <![CDATA[7%HNO3]]> 0.1476 0.2717 0.0594 0.0497

[0053] Table 2:

[0054] Initial activated carbon-based carbon 70.77 5.21 5.09 5% HCl 70.38 5.21 5.86 <![CDATA[5%HNO3]]> 70.71 5.93 8.53 <![CDATA[5%H2O2]]> 69.15 5.66 5.86 <![CDATA[1%HNO3]]> 70.82 5.39 7.03 <![CDATA[3%HNO3]]> 70.76 5.76 8.14 <![CDATA[7%HNO3]]> 70.49 5.20 8.76

[0055] The experimental data above show that soaking the initial activated carbon base in 5% nitric acid results in the best adsorption effect on carbon dioxide. Furthermore, this application modifies activated carbon using only one acid, employing a one-step method to obtain modified activated carbon. This avoids the use of multiple elements or multi-step processes, resulting in a simple and low-cost operation. The obtained modified activated carbon is inexpensive, pollution-free, has low requirements for adsorption conditions, is widely applicable, and has a low cost.

[0056] Understandably, referring to Figure 3 The monoprotic inorganic strong acid is nitric acid. Step S200 includes, but is not limited to, the following steps:

[0057] Step S210: Soak the initial activated carbon-based carbon in 5% nitric acid for 8 hours to enhance the functional groups in the initial activated carbon-based carbon and obtain the target activated carbon-based carbon.

[0058] In this embodiment, the monoprotic inorganic strong acid selected is nitric acid, specifically nitric acid with a concentration of 5%. The initial activated carbon-based carbon is soaked in nitric acid with a concentration of 5% for 8 hours to enhance the functional groups in the initial activated carbon-based carbon, thereby obtaining the target activated carbon-based carbon. In other embodiments, hydrochloric acid with a concentration of 5% and hydrogen peroxide, or nitric acid with a concentration between 3% and 7% can also be selected, and the method is not limited to the embodiments of this application.

[0059] Understandably, the raw material mass percentage of the coal is: 25%–30% Taixi coal powder, 5%–10% coking coal powder, 5%–15% tar, 15%–25% auxiliary binder, and 30%–40% bamboo charcoal powder.

[0060] In this embodiment, the raw material mass percentage of the coal is: 28% Taixi coal powder, 7% coking coal powder, 10% tar, 20% auxiliary binder, and 35% bamboo charcoal powder. In other embodiments, the raw material mass percentage of the coal may also be: 25% to 30% of Taixi coal powder, 5% to 10% of coking coal powder, 5% to 15% of tar, 15% to 25% of auxiliary binder, and 30% to 40% of bamboo charcoal powder, and the sum of these percentages shall be 100%, and is not limited to the embodiments of this application.

[0061] It is understandable that the mass percentage of the mixture of carbon dioxide and water vapor is 25%–35% carbon dioxide and 65%–75% water vapor.

[0062] In some embodiments, the mass percentage of the mixed gas of carbon dioxide and water vapor is 30% carbon dioxide and 70% water vapor.

[0063] It should be noted that the high-temperature environment refers to a temperature environment above 900℃.

[0064] It is understandable that Taixi coal powder is produced by grinding Taixi coal after dry distillation at 580℃ to 620℃ for 50 to 70 minutes.

[0065] It should be noted that the improved charcoal production process involves adding a dry distillation process before grinding Taixi coal. The Taixi coal is dry distilled at 580℃ to 620℃ for 50 to 70 minutes before grinding. During this process, some of the volatile organic compounds in the coal can be separated, making the coal purer. It can also form some pores in the process, achieving the purpose of pore formation.

[0066] In this embodiment, Taixi coal powder is obtained by grinding Taixi coal after dry distillation at 600°C for 60 minutes; in other embodiments, Taixi coal powder can also be obtained by grinding Taixi coal after dry distillation at any temperature between 580°C and 620°C for any time between 50 minutes and 70 minutes, and is not limited to the embodiments of this application.

[0067] It is understandable that the auxiliary binder is either phenolic residue or lignin.

[0068] It should be noted that when selecting auxiliary binders, Taixi coal powder was used as raw material, and a certain amount of phenolic residue was added. The product was prepared using activated carbon processing technology to form a special product. The CO2 adsorption test results are shown in Table 3. The CO2 adsorption performance was improved, reaching 43 ml / g, which is a significant improvement. The experiment shows that this method does indeed improve CO2 adsorption and can be further improved in the future. The addition of phenolic residue can improve the CO2 adsorption effect, but it also carries the risk of reducing strength. Therefore, it is not advisable to completely replace binders such as tar; the ratio should be appropriate. Table 3:

[0069]

[0070] Specifically, the raw materials selected for the raw coal are Taixi coal, coking coal, and bamboo charcoal powder. The selected binder is a combination of coal tar and phenolic residue, or a binder formed by a combination of coal tar and lignin. The raw coal is then mixed evenly using a mixing device. During mixing, a certain pressure is required to force the binder to mix evenly, resulting in a mixture. The mixture is then extruded to obtain columnar material. The columnar material is then slowly carbonized at low temperature using a carbonization device according to a temperature gradient, resulting in a carbonized material with a uniform structure and high basic strength. The oxygen content is strictly controlled. Under high temperature and oxygen-free environment, the carbonized material is slowly activated for 2 to 3 hours using an activation device with a mixed gas of 30% carbon dioxide and 70% water vapor to obtain activated carbon-based carbon. The water vapor content used for activation is reduced by 30%, with only 70% of the water vapor being used by mass, extending the activation time and avoiding overburning. Protective gas can be added if necessary. Finally, the activated carbon-based carbon is rinsed and dried to obtain activated carbon.

[0071] Understandably, referring to Figure 4 Following step S300, the following steps are also included, but are not limited to:

[0072] Step S410: Quantitatively detect the functional groups in the initial activated carbon-based carbon and the modified activated carbon to obtain the detection results of the first functional group corresponding to the initial activated carbon-based carbon and the detection results of the second functional group corresponding to the modified activated carbon.

[0073] Step S420: The adsorption performance of the initial activated carbon-based carbon and the modified activated carbon on carbon dioxide is tested respectively to obtain the first adsorption performance test result corresponding to the initial activated carbon-based carbon and the second adsorption performance test result corresponding to the modified activated carbon.

[0074] Step S430: Compare the detection results of the first functional group and the detection results of the second functional group to obtain the first comparison result;

[0075] Step S440: Compare the first adsorption performance test result and the second adsorption performance test result to obtain the second comparison result;

[0076] Step S450: Determine the effect of the number of functional groups on the carbon dioxide adsorption performance based on the first comparison result and the second comparison result.

[0077] For example, the detection results of the first functional group and the detection results of the second functional group are shown in the table below:

[0078] Initial activated carbon-based carbon 0.7787 0.0992 0.0088 -0.0371 Modified activated carbon 0.2972 0.2695 0.0571 0.0462

[0079] Based on the experimental data above, it can be seen that the functional group content of the modified activated carbon after oxidation with 5% nitric acid is significantly improved compared to the initial activated carbon. The results of the first and second adsorption performance tests are shown in the table below:

[0080] Initial activated carbon-based carbon 70.77 5.21 Modified activated carbon 70.71 5.93

[0081] The experimental data above show that the modified activated carbon after oxidation with 5% nitric acid has almost the same adsorption rate for carbon tetrachloride as the original activated carbon, but the CO2 adsorption rate of the modified activated carbon is significantly increased. It meets the experimental objectives.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

[0084] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for improving the carbon dioxide adsorption performance of activated carbon, characterized in that, include: Obtain initial activated carbon-based carbon; The initial activated carbon-based carbon was soaked in 5% nitric acid for 8 hours to enhance the functional groups in the initial activated carbon-based carbon, thereby obtaining the target activated carbon-based carbon. The target activated carbon-based carbon is sequentially rinsed and dried to obtain modified activated carbon; The process of obtaining the initial activated carbon-based carbon includes: Raw coal is obtained and mixed in a certain proportion to obtain a mixture. The raw coal has the following mass percentages: 25%–30% Taixi coal powder, 5%–10% coking coal powder, 5%–15% tar, 15%–25% auxiliary binder, and 30%–40% bamboo charcoal powder. The Taixi coal powder is obtained by grinding Taixi coal after dry distillation at 580℃ to 620℃ for 50 min to 70 min. The auxiliary binder is either phenolic residue or lignin. The mixture is added to an activated carbon molding machine to extrude the mixture and obtain columnar material; The columnar material is carbonized using static temperature-controlled carbonization technology to obtain carbonized material; Under conditions of above 900°C and oxygen-free environment, the carbonized material is slowly activated for 2 to 3 hours by a mixture of carbon dioxide and water vapor to obtain the initial activated carbon-based carbon; the mass percentage of the mixture of carbon dioxide and water vapor is 25% to 35% carbon dioxide and 65% to 75% water vapor.

2. The method for improving the carbon dioxide adsorption performance of activated carbon according to claim 1, characterized in that, After sequentially rinsing and drying the target activated carbon-based carbon to obtain modified activated carbon, the process includes: The functional groups in the initial activated carbon-based carbon and the modified activated carbon are quantitatively detected to obtain the detection results of the first functional group corresponding to the initial activated carbon-based carbon and the detection results of the second functional group corresponding to the modified activated carbon. The adsorption performance of the initial activated carbon-based carbon and the modified activated carbon on carbon dioxide was tested respectively to obtain a first adsorption performance test result corresponding to the initial activated carbon-based carbon and a second adsorption performance test result corresponding to the modified activated carbon. The first functional group detection result and the second functional group detection result are compared to obtain the first comparison result; The first adsorption performance test result and the second adsorption performance test result are compared to obtain a second comparison result; Based on the first comparison result and the second comparison result, the effect of the number of functional groups on the carbon dioxide adsorption performance is determined.

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