A method for preparing a sulfur-doped porous carbon-based carbon dioxide adsorbent

Abstract

The present application relates to a kind of preparation methods of sulfur-doped porous carbon-based carbon dioxide adsorbent, the method is with coconut shell as carbon source, with pollution-free potassium thiosulfate as activator and sulfur source, using one-step method (carbonization and activation simultaneously) High sulfur content, high carbon dioxide selectivity and adsorption of sulfur-doped porous carbon-based carbon dioxide adsorbent.The preparation method of the present application is simple, easy to operate, saves resources, and has high preparation efficiency.A new heating temperature system is used to obtain a high selectivity, high cycle performance sulfur-doped porous carbon product that meets the requirements of industrial carbon dioxide adsorption.In the present application, the compound potassium thiosulfate can be used as a sulfur source and an activator to achieve a one-step preparation process, and the compound is environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide adsorbent preparation technology, and in particular to a method for preparing a sulfur-doped porous carbon-based carbon dioxide adsorbent. Background Technology

[0002] Carbon dioxide (CO2) is the leading greenhouse gas contributing to global warming and climate change. Carbon capture and storage (CFS) technology has become a promising approach to reducing CO2 emissions. Porous carbon materials possess high surface area and porosity, and heteroatom-doped carbon materials further enhance their CO2 adsorption performance and selectivity, enabling them to effectively capture CO2. Sulfur-doped porous carbon materials have attracted considerable attention due to their excellent performance, and their preparation typically involves two processes: carbonization and activation. Existing literature indicates that using sodium thiosulfate as an activator and various biomass products (glucose, sucrose, and gelatin) as carbon sources, porous carbon with a sulfur content of 2-3 wt% can be prepared, but its CO2 adsorption capacity and selectivity are generally moderate. Using low-cost phenolic resin and sodium thiosulfate as carbon and sulfur sources respectively, porous carbon prepared using nanocasting technology has a sulfur content of 2.89 wt% and a CO2 adsorption capacity of 1.35–2.10 mmol / g. -1 Anthracite was selected as the carbon source, and Na2S2O3 and NaNH2 were used as activating and functionalizing reagents. The resulting porous carbon had a sulfur content of 2.5 wt% and a CO2 adsorption capacity of 3.73 mmol g. -1 It exhibits a certain degree of adsorption selectivity for binary CO2 / CH4 mixtures. The methods for preparing sulfur-doped porous carbon materials vary, but all involve two steps: carbonization and activation. Furthermore, the raw materials used are not environmentally friendly, such as anthracite and phenolic resin. The sulfur content of porous carbon has a significant impact on its performance, especially on its carbon dioxide adsorption capacity and selectivity. The sulfur content of porous carbon prepared by existing technologies needs to be improved. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a sulfur-doped porous carbon-based carbon dioxide adsorbent, which uses a one-step method (simultaneous carbonization and activation) to prepare a sulfur-doped porous carbon-based carbon dioxide adsorbent with high sulfur content, high carbon dioxide selectivity and adsorption capacity.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for preparing a sulfur-doped porous carbon-based carbon dioxide adsorbent, using coconut shell as a carbon source and non-polluting potassium thiosulfate as both an activator and a sulfur source, employs a one-step method (simultaneous carbonization and activation) to prepare the sulfur-doped porous carbon-based carbon dioxide adsorbent. The specific steps include the following:

[0006] 1) Use a grinder to grind the dried coconut shells into powder. The particle size of the crushed coconut shells should be 80-120 mesh.

[0007] 2) Prepare a saturated potassium thiosulfate solution using a mixer.

[0008] 3) Mix the crushed coconut shells with a saturated potassium thiosulfate solution at a mass ratio of 1:(1-2). Stir vigorously under microwave heating conditions; the microwave heating temperature is 60-90℃, and the stirring time is 5-8 hours.

[0009] 4) After dehydrating the mixture obtained in step 1) in a centrifuge for 1-2 hours, it is then simultaneously activated and carbonized in a one-step process under a nitrogen atmosphere, heated to 650-750℃. The nitrogen flow rate is 400-500 ml / min. Based on theoretical analysis and experimental exploration, the preferred heating temperature regime is as follows:

[0010] Heat from room temperature to 300-400℃ at a rate of 3-5℃ / minute, and hold for 1-2 hours;

[0011] Continue heating to 500–550℃ at a rate of 2–4℃ / minute, and hold for 0.5–2 hours;

[0012] Continue heating to 650–750℃ at a heating rate of 3–5℃ / minute, and hold for 1–2 hours;

[0013] 5) After cooling the material obtained in step 4), rinse it in a washing tower until the pH value of the filtrate is 6.8 to 7.2. Then send it to a drying oven to dry and obtain the final product, which is a powdered carbon dioxide adsorbent.

[0014] The highest sulfur content in the adsorbent obtained by this invention is 12.86 wt%; in a CO2-N2 binary gas mixture, the CO2 / N2 adsorption selectivity of the adsorbent is 100.

[0015] Compared with existing technologies, the beneficial effects of this invention are:

[0016] 1) This invention uses a one-step method (simultaneous carbonization and activation) to prepare sulfur-doped porous carbon-based carbon dioxide adsorbents. The preparation method is simple, easy to operate, resource-saving, and highly efficient.

[0017] 2) Applying a one-step method, through theoretical analysis and experimental exploration, and employing a novel heating temperature regime, a highly selective and high-cycle-performance sulfur-doped porous carbon product meeting the requirements for industrial carbon dioxide adsorption was obtained. The product specifications are as follows:

[0018] The sulfur content can reach up to 12.86 wt%, and the optimal S-doped porous carbon exhibits an adsorption capacity of up to 4.38 mmol g under conditions of 25 °C and one atmosphere. -1 The adsorption capacity can reach up to 6.35 mmol g under conditions of 0°C and one atmosphere of pressure. -1 Stable cycling performance; the adsorbent's adsorption capacity remained unchanged after 112 consecutive adsorption-desorption cycles. Excellent CO2 / N2 adsorption selectivity; in a CO2-N2 binary gas mixture (where nitrogen volume percentage is 90% and CO2 volume percentage is 10%), the product's CO2 / N2 adsorption selectivity is up to 100.

[0019] 3) The compound potassium thiosulfate can be used as both a sulfur source and an activator. Moreover, this compound is green and environmentally friendly, which is a necessary condition for implementing the one-step preparation of sulfur-doped porous carbon dioxide adsorbent. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the present invention.

[0021] Figure 2 This is the carbon dioxide adsorption curve for Example 1.

[0022] Figure 3 This is a CO2 / N2 adsorption selectivity curve for Example 1.

[0023] Figure 4 This is a graph showing the carbon dioxide adsorption curve for Example 2.

[0024] Figure 5 This is a CO2 / N2 adsorption selectivity curve for Example 2.

[0025] Figure 6 This is the carbon dioxide adsorption curve for Example 3.

[0026] Figure 7 This is the CO2 / N2 adsorption selectivity curve for Example 3. Detailed Implementation

[0027] The present invention will be described in detail below with reference to specific embodiments, but the scope of the present invention is not limited to the following embodiments.

[0028] Example 1:

[0029] like Figure 1 As shown, a method for preparing a sulfur-doped porous carbon-based carbon dioxide adsorbent is as follows:

[0030] The dried coconut shells were crushed to a particle size of 100 mesh using a pulverizer. A saturated potassium thiosulfate solution was prepared using a mixer. The crushed coconut shells and the saturated potassium thiosulfate solution were mixed at a mass ratio of 1:1 and vigorously stirred for 8 hours under constant temperature conditions of microwave heating to 80°C. The material was filtered out and dehydrated in a centrifuge for 2 hours. Then, it was simultaneously activated and carbonized in a one-step process under a nitrogen flow rate of 500 ml / min. The heating temperature regime was as follows:

[0031] Heat from room temperature to 300℃ at a heating rate of 5℃ / minute and hold for 1 hour; continue heating to 500℃ at a heating rate of 3℃ / minute and hold for 0.5 hours; continue heating to 650℃ at a heating rate of 5℃ / minute and hold for 1 hour.

[0032] After completion, the cooled material is rinsed in a washing tower until the pH of the filtrate is approximately 7. After drying in a drying oven for 10 hours, the final product, a powdered carbon dioxide adsorbent, is obtained. Its main indicators are shown in Sample 1 of Table 1, and the carbon dioxide adsorption curve is shown in [Table data missing]. Figure 2 The CO2 / N2 adsorption selectivity curves are shown below. Figure 3 .

[0033] Example 2:

[0034] Preparation process as follows Figure 1 As shown, dried coconut shells were pulverized to a particle size of 90 mesh using a pulverizer. A saturated potassium thiosulfate solution was prepared using a mixer. The pulverized coconut shells and the saturated potassium thiosulfate solution were mixed at a mass ratio of 1:1.5 and vigorously stirred for 6 hours under microwave heating at a constant temperature of 70°C. The material was filtered out and dehydrated in a centrifuge for 2 hours. Then, it was simultaneously activated and carbonized in a one-step process under a nitrogen flow rate of 450 ml / min. The heating temperature regime was as follows:

[0035] Heat from room temperature to 320℃ at a heating rate of 4℃ / minute and hold for 1 hour; continue heating to 530℃ at a heating rate of 4℃ / minute and hold for 0.5 hours; continue heating to 680℃ at a heating rate of 5℃ / minute and hold for 1 hour.

[0036] After completion, the cooled material is rinsed in a washing tower until the pH of the filtrate is approximately 7. After drying in a drying oven for 10 hours, the final product, a powdered carbon dioxide adsorbent, is obtained. Its main indicators are shown in Sample 2 of Table 1, and the carbon dioxide adsorption curve is shown in [Table data missing]. Figure 4 The CO2 / N2 adsorption selectivity curves are shown below. Figure 5 .

[0037] Example 3:

[0038] Preparation process as follows Figure 1As shown, dried coconut shells were pulverized to a particle size of 100 mesh using a pulverizer. A saturated potassium thiosulfate solution was prepared using a mixer. The pulverized coconut shells and the saturated potassium thiosulfate solution were mixed at a mass ratio of 1:2 and vigorously stirred for 8 hours under microwave heating at a constant temperature of 65°C. The material was filtered out, dehydrated in a centrifuge for 2 hours, and then simultaneously activated and carbonized in a one-step process under a nitrogen flow rate of 480 ml / min. The heating temperature regime was as follows:

[0039] Heat from room temperature to 350℃ at a heating rate of 5℃ / min, and hold for 1 hour. Continue heating to 510℃ at a heating rate of 3℃ / min, and hold for 1 hour. Heat to 720℃ at a heating rate of 4℃ / min, and hold for 2 hours.

[0040] After completion, the cooled material is rinsed in a washing tower until the pH of the filtrate is approximately 7. After drying in a drying oven for 10 hours, the final product, a powdered carbon dioxide adsorbent, is obtained. Its main indicators are shown in Table 1 (Sample 3), and the carbon dioxide adsorption curve is shown in [Table 1]. Figure 6 The CO2 / N2 adsorption selectivity curves are shown below. Figure 7 .

[0041] Table 1. Key Product Indicators for Examples 1-3

[0042]

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a sulfur-doped porous carbon-based carbon dioxide adsorbent, characterized by, The method is to prepare the sulfur-doped porous carbon-based carbon dioxide adsorbent by using coconut shell as carbon source, using pollution-free potassium thiosulfate as activator and sulfur source, and adopting one-step method, and specifically comprises the following method steps: 1) mixing the crushed coconut shell with saturated potassium thiosulfate solution, and stirring under the condition of microwave heating; 2) dehydrating the mixture obtained in step 1) in a centrifuge, and then simultaneously activating and carbonizing under the nitrogen atmosphere by adopting one-step method, and the heating temperature system is as follows: heating from room temperature to 300-400℃ at a heating rate of 3-5℃ / min, and keeping warm for 1-2 hours; continuing to heat to 500-550℃ at a heating rate of 2-4℃ / min, and keeping warm for 0.5-2 hours; continuing to heat to 650-750℃ at a heating rate of 3-5℃ / min, and keeping warm for 1-2 hours; 3) washing the material obtained in step 2) in a washing tower until the pH value of the filtrate is 6.8-7.2, and then drying in a drying box to obtain the final product, which is a powdered carbon dioxide adsorbent; The crushing particle size of the crushed coconut shell is 80-120 mesh; The mixing mass ratio of the crushed coconut shell to the saturated potassium thiosulfate solution is 1:(1-2); The microwave heating temperature in step 1) is 60-90℃, and the stirring time is 5-8 hours; The carbon dioxide adsorbent prepared by the above method has a CO2 / N2 adsorption selectivity of 97-100 in CO2-N2 binary mixed gas.

2. The method of claim 1, wherein the porous carbon-based carbon dioxide adsorbent is sulfur-doped. The nitrogen flow rate in step 2) is 400-500ml / min.

3. A carbon dioxide adsorbent produced by a production method of a carbon dioxide adsorbent using the sulfur-doped porous carbon-based carbon dioxide adsorbent according to claim 1 or 2, characterized by, The highest sulfur content in the adsorbent is 12.86wt%.

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