Activated carbon for propane adsorption and preparation method thereof

Abstract

The invention relates to activated carbon for propane adsorption and a preparation method thereof.The method comprises the steps that S1, activated carbon makes contact with an alkali solution for alkali treatment, a first solid product is taken out, and alkali modified activated carbon is obtained; s2, contacting the alkali modified activated carbon with a solution containing metal ions for metal modification, and taking out a second solid product; wherein the metal ions comprise one or more of magnesium ions, calcium ions and zinc ions. The modified activated carbon prepared by the method disclosed by the invention has relatively high adsorption capacity when being used for propane adsorption.

Description

Activated carbon for propane adsorption and its preparation method Technical Field

[0001] This application relates to an activated carbon for propane adsorption and a method for preparing the same. Background Technology

[0002] Short-chain low-carbon alkanes (C1-C3) are more difficult to adsorb than large, polar gas molecules. Therefore, the removal of small-molecule hydrocarbon components encountered in the purification of motor vehicle exhaust, the purification of hydrogen sources, the removal of impurities from natural gas, and the treatment of volatile organic compounds (VOCs) is a technical problem of great concern.

[0003] Activated carbon, due to its high specific surface area, abundant pore structure, and simple industrial production, is a widely used adsorption material for gas molecules, heavy metal ions, and organic matter. Modification of activated carbon can regulate its pore structure and surface chemical properties, thereby further enhancing its physical and chemical adsorption of small molecule hydrocarbons. CN105251444A discloses a method for modifying activated carbon-based propane adsorbent with trace amounts of potassium hydroxide. A simple process is used to impregnate coal-based activated carbon in a dilute potassium hydroxide solution and then dry it to obtain an activated carbon-based propane adsorbent with improved performance. CN103990434A discloses a propane adsorbent, its preparation method, and its application. This method involves impregnating coconut shell activated carbon in a hydrofluoric acid solution at 120-180°C. o After hydrothermal treatment for 1-7 days, the propane adsorbent is dried to improve the purification efficiency and adsorption capacity of propane. CN116328720A discloses a carbonaceous adsorbent with poor propane desorption properties, its preparation method, dynamic pore optimization technology and application. A benzoxazine-based polymer is used as a raw material for carbonization treatment to obtain microporous carbon with a pore size distribution of 0.5 nm. By spatially confining the adsorbed propane, the purpose of poor propane desorption is achieved. Summary of the Invention

[0004] The purpose of this disclosure is to provide activated carbon for propane adsorption and its preparation method. The method disclosed herein is simple and easy to implement, and the modified activated carbon prepared has a high adsorption capacity when used for propane adsorption.

[0005] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing modified activated carbon for propane adsorption, the method comprising: S1, contacting activated carbon with an alkaline solution for alkaline treatment, and removing a first solid product to obtain alkaline-modified activated carbon; S2, contacting the alkaline-modified activated carbon with a solution containing metal ions for metal modification, and removing a second solid product; wherein the metal ions include one or more of magnesium ions, calcium ions, and zinc ions.

[0006] Optionally, in step S1, the conditions for the alkali treatment include: a temperature of 20-25°C and a time of 1-6 hours.

[0007] Optionally, in step S1, the amount of alkaline solution used relative to 1g of activated carbon is 4-10mL, calculated as alkali metal hydroxide, and the concentration of the alkaline solution is 4-8% by weight; preferably, the amount of alkaline solution used is 6-10mL, calculated as alkali metal hydroxide, and the concentration of the alkaline solution is 4-6% by weight.

[0008] Optionally, in step S2, the conditions for metal modification include: a temperature of 20-25°C and a time of 1-6 hours.

[0009] Optionally, the amount of the metal ion-containing solution, calculated as a metal salt, is 0.2-1 mmol relative to 1 g of the activated carbon, preferably 0.4-1 mmol.

[0010] Optionally, the activated carbon has a particle size of 10-24 mesh; the activated carbon is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, coal-derived activated carbon and wood-based activated carbon, preferably coconut shell activated carbon.

[0011] Optionally, the alkaline solution contains one or more of potassium hydroxide, sodium hydroxide, barium hydroxide, and calcium hydroxide, preferably potassium hydroxide; the solution containing metal ions contains one or more of magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium chloride, and zinc chloride.

[0012] Optionally, step S1 includes: ultrasonically cleaning the activated carbon and then contacting it with the alkaline solution for alkaline treatment; the conditions for ultrasonic treatment include: temperature of 20-30℃, time of 2-3h, ultrasonic frequency of 30-50kHz, and power of 500-1300W.

[0013] Optionally, step S2 includes: cleaning and drying the alkali-modified activated carbon, and then contacting it with the magnesium-containing solution to perform the metal modification; the drying conditions include: a temperature of 60-100°C. o C, the time is 3-6 hours.

[0014] The second aspect of this disclosure provides a modified activated carbon prepared by the method provided in the first aspect of this disclosure.

[0015] Optionally, based on the dry weight of the modified activated carbon, the content of modified metal in the modified activated carbon is 0.14-3.10% by weight.

[0016] Through the above technical solution, the method disclosed herein can significantly improve the adsorption capacity of the prepared modified activated carbon by alkali treatment and metal modification, and it has a good adsorption effect when used for propane adsorption.

[0017] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 shows the N2 adsorption isotherms of the modified activated carbon and the unmodified activated carbon of the present disclosure. Detailed Implementation

[0019] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0020] The first aspect of this disclosure provides a method for preparing modified activated carbon for propane adsorption, the method comprising: S1, contacting activated carbon with an alkaline solution for alkaline treatment, and removing a first solid product to obtain alkaline-modified activated carbon; S2, contacting the alkaline-modified activated carbon with a solution containing metal ions for metal modification, and removing a second solid product; wherein the metal ions include one or more of magnesium ions, calcium ions and zinc ions.

[0021] The method disclosed herein, through alkali treatment and metal modification of activated carbon, can regulate the adsorption sites on the surface of activated carbon, which is beneficial to improving the adsorption performance of activated carbon for short-chain low-carbon alkanes. The modified activated carbon prepared has a high adsorption capacity and exhibits good adsorption effect when used in the propane adsorption process.

[0022] According to this disclosure, alkali treatment can be carried out at room temperature. Preferably, the alkali treatment is carried out under stirring conditions, such as electromagnetic stirring, to ensure that the activated carbon is fully dispersed and in full contact with the alkali solution, thus promoting thorough alkali treatment. This disclosure does not impose specific limitations on the stirring speed, as long as it achieves sufficient mixing between the activated carbon and the alkali solution. In one specific embodiment of this disclosure, in step S1, the alkali treatment conditions include: a temperature of 20-25°C and a time of 1-6 hours. By subjecting activated carbon to alkali treatment under the above conditions, the pore size distribution of the activated carbon, especially the mesopore size distribution, can be further improved, which is beneficial for preparing modified carbon materials with higher adsorption capacity.

[0023] According to this disclosure, the amount and concentration of the alkaline solution can vary within a wide range. In one specific embodiment of this disclosure, in step S1, the amount of the alkaline solution, calculated as alkali metal hydroxide, relative to 1g of the activated carbon is 4-10mL, preferably 6-10mL, and the concentration of the alkaline solution is 4-8% by weight, preferably 4-6% by weight. In this embodiment, the appropriate concentration and amount of the alkaline solution can effectively improve the pore distribution and surface active site distribution of the activated carbon, which is beneficial for preparing modified carbon materials with higher adsorption capacity.

[0024] According to this disclosure, alkali treatment can be carried out at room temperature. Preferably, metal modification is carried out under stirring conditions, such as electromagnetic stirring, to ensure that the activated carbon is fully dispersed and in full contact with the metal ion-containing solution, thereby promoting thorough metal modification. This disclosure does not impose specific limitations on the stirring speed, as long as it can achieve sufficient mixing between the activated carbon and the metal ion-containing solution. In one specific embodiment, in step S2, the conditions for metal modification include: a temperature of 20-25°C and a time of 1-6 hours.

[0025] According to this disclosure, the concentration of metal ions in the solution containing metal ions is not specifically limited, as long as the target amount of metal can be loaded onto the alkali-modified activated carbon. In one specific embodiment of this disclosure, the concentration of metal ions in the solution containing metal ions can be 20-100 mmol / L. According to this disclosure, the amount of metal ion-containing solution can vary within a wide range; relative to 1 g of activated carbon, the amount of metal ion-containing solution, calculated as metal salt, is 0.2-1 mmol, preferably 0.4-1 mmol. In this embodiment, an appropriate amount of metal can be loaded onto the alkali-modified activated carbon, resulting in modified activated carbon with superior adsorption capacity.

[0026] According to this disclosure, there are no specific limitations on the method for removing the first solid product and the second solid product. Any method known to those skilled in the art can be used, as long as the solid can be removed. For example, it can be centrifugation, filtration, static sedimentation, etc.

[0027] According to this disclosure, the activated carbon can be biological activated carbon, such as one or more selected from, but not limited to, coconut shell activated carbon, fruit shell activated carbon, coal-derived activated carbon, and wood-based activated carbon, preferably coconut shell activated carbon. The particle size of the activated carbon can vary within a wide range. In one embodiment, the particle size of the activated carbon is 10-24 mesh, preferably 15-20 mesh.

[0028] In one specific embodiment of this disclosure, the alkaline solution contains one or more of potassium hydroxide, sodium hydroxide, barium hydroxide, and calcium hydroxide, preferably potassium hydroxide; the solution containing metal ions may contain alkaline earth metal salts, calcium salts, zinc salts, etc. In one embodiment, the solution containing metal ions contains one or more of magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium chloride, and zinc chloride, preferably magnesium chloride and / or calcium chloride.

[0029] To remove impurities from the surface of activated carbon, physical cleaning methods can be used. In one specific embodiment of this disclosure, step S1 includes: ultrasonically cleaning the activated carbon followed by contacting it with an alkaline solution for alkaline treatment. The solution used for ultrasonic treatment can be any solution that does not react with activated carbon, such as deionized water, ethanol, methanol, etc. In one embodiment, the conditions for ultrasonic treatment include: a temperature of 20-30°C, a time of 2-3 hours, an ultrasonic frequency of 30-50 kHz, preferably 40 kHz, and a power of 500-1300 W. In this embodiment, impurities on the surface of activated carbon can be removed relatively completely, which is beneficial for preparing modified activated carbon with better adsorption capacity.

[0030] In one specific embodiment of this disclosure, step S2 includes: cleaning and drying the alkali-modified activated carbon, and then contacting it with the magnesium-containing solution to perform the metal modification; in this disclosure, deionized water can be used to rinse the alkali-modified activated carbon to remove residual alkali metal ions on its surface. Drying can be performed in an apparatus well known to those skilled in the art, such as a constant temperature drying oven, and the drying conditions may include a temperature of 60-100°C. o C, the time is 3-6 hours.

[0031] The second aspect of this disclosure provides a modified activated carbon prepared using the method provided in the first aspect of this disclosure. The modified activated carbon of this disclosure has a slightly reduced specific surface area, but due to the loading of metal ions, the surface of the activated carbon is rich in adsorption sites, resulting in a high adsorption capacity for propane.

[0032] In one specific embodiment of this disclosure, the modified activated carbon has an adsorption capacity of 0.25-0.43 mg / g for propane at 25°C.

[0033] In one specific embodiment of this disclosure, based on the dry weight of the modified activated carbon, the content of modified metal in the modified activated carbon is 0.14-3.10 by weight.

[0034] In one specific embodiment of this disclosure, the metal ion is magnesium ion, and the content of magnesium ion in the modified activated carbon is 0.14-0.64% by weight, based on the dry weight of the modified activated carbon.

[0035] In one specific embodiment of this disclosure, the metal ion is calcium ion, and the calcium ion content in the modified activated carbon is 0.15-5.16% by weight, based on the dry weight of the modified activated carbon.

[0036] In one specific embodiment of this disclosure, the metal ion is zinc ion, and the zinc ion content in the modified activated carbon is 0.06-5.56% by weight, based on the dry weight of the modified activated carbon.

[0037] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0038] The activated carbon used in the examples and comparative examples was purchased from Inokai, a petrochemical-grade activated carbon with a particle size of 10-24 mesh, derived from fruit shells and coconut shells. The anhydrous MgCl2 had a purity of 99% by weight. KOH was electronic grade, 99.99% metal-based, excluding sodium.

[0039] Example 1S1: Coconut shell activated carbon was ultrasonically cleaned with deionized water at 25°C three times, for a total treatment time of 2 hours. The ultrasonic frequency was 40kHz and the power was 1300W. 15g of dried, washed coconut shell activated carbon was then immersed in a 6% by weight, 100mL KOH solution at 25°C with electromagnetic stirring for 6 hours. The solution was filtered and rinsed with deionized water. o Drying at C yields alkali-modified activated carbon.

[0040] S2. Weigh 5g of the alkali-modified activated carbon prepared in step S1 and impregnate it in an aqueous solution of 0.09g MgCl2 (containing 1mmol of MgCl2). Stir magnetically at 25℃ for 6h, filter, and 80 o The modified activated carbon was obtained by drying at C for 3 hours.

[0041] Example 2 uses the same method as Example 1 to prepare modified activated carbon, except that in step S2, 5g of the alkali-modified activated carbon prepared in step S1 is weighed and impregnated in an aqueous solution of 0.19g MgCl2 (where the content of MgCl2 is 2mmol).

[0042] Example 3 uses the same method as Example 1 to prepare modified activated carbon, except that in step S2, 5g of the alkali-modified activated carbon prepared in step S1 is weighed and impregnated in 0.285g of MgCl2 aqueous solution (where the content of MgCl2 is 3mmol).

[0043] Example 4 uses the same method as Example 1 to prepare modified activated carbon, except that in step S2, 5g of the alkali-modified activated carbon prepared in step S1 is weighed and impregnated in 0.475g of MgCl2 aqueous solution (where the content of MgCl2 is 5mmol).

[0044] Example 5 uses the same method as Example 1 to prepare modified activated carbon, except that in step S2, 5g of the alkali-modified activated carbon prepared in step S1 is weighed and impregnated in 0.222g of CaCl2 aqueous solution (where the content of CaCl2 is 2mmol).

[0045] Example 6 uses the same method as Example 1 to prepare modified activated carbon, except that in step S2, 5g of the alkali-modified activated carbon prepared in step S1 is weighed and impregnated in 0.272g of ZnCl2 aqueous solution (where the content of ZnCl2 is 2mmol).

[0046] Example 7 uses the same method as Example 1 to prepare modified activated carbon, except that in step S1, 5g of dried washed coconut shell activated carbon is immersed in 4% by weight, 20mL of KOH solution at 25°C and electromagnetic stirring is turned on for 6h.

[0047] Comparative Example 1: Coconut shell activated carbon was ultrasonically cleaned with deionized water at 25°C, repeated three times for a total treatment time of 2 hours. The dried, washed coconut shell activated carbon was then immersed in a 6% (w / w) KOH solution with electromagnetic stirring for 6 hours. It was then filtered and rinsed with deionized water at 80°C. o After drying at C, modified activated carbon is obtained.

[0048] Comparative Example 2: 5g of activated carbon was impregnated in a 0.09g MgCl2 aqueous solution (containing 1mmol of MgCl2), and stirred electromagnetically at 25℃ for 6h. The mixture was then filtered. o After drying at C, modified activated carbon is obtained.

[0049] Comparative Example 3: 5g of activated carbon was impregnated in a 0.09g MgCl2 aqueous solution (containing 1mmol of MgCl2), and stirred electromagnetically at 25℃ for 6h. The mixture was then filtered. o Dry at 80°C for 3 hours. Then, impregnate the dried activated carbon in a 6% (w / w) 33 mL KOH solution and stir electromagnetically for 6 hours. Filter and rinse with deionized water. o After drying at C, modified activated carbon is obtained.

[0050] Test Example (1): The surface area and pore volume characteristics of the activated carbon and unmodified activated carbon prepared in the examples and comparative examples were characterized by N2 isothermal adsorption-desorption technology using an ASAP2020 analyzer manufactured by Micro-meritics, USA. The samples were pretreated by vacuum degassing before the test.

[0051] (2) The propane adsorption performance of the modified activated carbon and unmodified activated carbon prepared in the examples and comparative examples was detected by gas chromatography-flame ionization-thermal conductivity detector.

[0052] (3) The content of metal ions in the modified activated carbon and unmodified activated carbon prepared in the examples and comparative examples was analyzed by semi-quantitative SEM-EDS, and the results were normalized semi-quantitative results.

[0053] Table 1

[0054] As shown in Table 1, the modified activated carbon prepared in this embodiment exhibits a significantly improved propane adsorption capacity compared to the activated carbon prepared in the comparative example. Comparative example 3 employed a method of first loading metal and then impregnating with alkali; the modified activated carbon prepared by this method had a lower metal content and a relatively lower adsorption capacity.

[0055] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0056] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0057] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing modified activated carbon for propane adsorption, the method comprising: S1. Activated carbon is contacted with an alkaline solution for alkaline treatment, and the first solid product is taken out to obtain alkaline modified activated carbon. S2. The alkali-modified activated carbon is contacted with a solution containing metal ions to perform metal modification, and a second solid product is taken out; wherein the metal ions include one or more of magnesium ions, calcium ions and zinc ions.

2. The method according to claim 1, wherein, In step S1, the conditions for alkali treatment include: a temperature of 20-25°C and a time of 1-6 hours.

3. The method according to claim 1, wherein, In step S1, relative to 1g of activated carbon, the amount of alkaline solution used is 4-10mL based on alkali metal hydroxide, and the concentration of the alkaline solution is 4-8% by weight; preferably, the amount of alkaline solution used is 6-10mL based on alkali metal hydroxide, and the concentration of the alkaline solution is 4-6% by weight.

4. The method according to claim 1, wherein, In step S2, the conditions for metal modification include: a temperature of 20-25°C and a time of 1-6 hours.

5. The method according to claim 1, wherein, The amount of the metal ion-containing solution, calculated as metal salt, is 0.2-1 mmol relative to 1 g of activated carbon, preferably 0.4-1 mmol.

6. The method according to claim 1, wherein, The activated carbon has a particle size of 10-24 mesh; the activated carbon is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, coal-derived activated carbon and wood-derived activated carbon, preferably coconut shell activated carbon.

7. The method according to claim 1, wherein, The alkaline solution contains one or more of potassium hydroxide, sodium hydroxide, barium hydroxide, and calcium hydroxide, preferably potassium hydroxide; the solution containing metal ions contains one or more of magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium chloride, and zinc chloride.

8. The method according to claim 1, wherein, Step S1 includes: ultrasonically cleaning the activated carbon and then contacting it with the alkaline solution for alkaline treatment; the conditions for ultrasonic treatment include: temperature of 20-30℃, time of 2-3h, ultrasonic frequency of 30-50kHz, and power of 500-1300W.

9. The method according to claim 1, wherein, Step S2 includes: cleaning and drying the alkali-modified activated carbon, and then contacting it with the magnesium-containing solution to perform the metal modification; the drying conditions include: a temperature of 60-100°C. o C, the time is 3-6 hours.

10. Modified activated carbon prepared by the method according to any one of claims 1-9.

11. The modified activated carbon according to claim 10, wherein, Based on the dry weight of the modified activated carbon, the content of modified metal in the modified activated carbon is 0.14-3.10% by weight.

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