Carbon dioxide adsorbent, method for preparing the same, and use thereof
By mixing carbide slag and fly ash and calcining at high temperature to generate Ca12Al14O33, a stable framework is constructed, which solves the problem of pore collapse of carbon dioxide adsorbents after multiple cycles, and realizes low-cost and high-efficiency CO2 capture and industrial solid waste resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 이너 몽골리아 일렉트릭 파워 그룹 컴퍼니 리미티드 이너 몽골리아 일렉트릭 파워 리서치 인스티튜트 브랜치
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-09
AI Technical Summary
In existing technologies, the pore structure of carbon dioxide adsorbents collapses after multiple cycles, resulting in a decrease in specific surface area and a reduction in cycle capture capacity. Furthermore, existing modification methods are costly or difficult to achieve the synergistic high-value utilization of various industrial solid wastes.
A mixture of calcium carbide slag and fly ash is calcined at high temperature to generate Ca12Al14O33, which forms a stable multiphase composite support framework, prevents calcium oxide particle agglomeration, reduces costs, and achieves synergistic effects of multi-component solid waste.
It improves the cycle stability and specific surface area of carbon dioxide adsorbents, reduces preparation costs, opens up a high-value utilization path for the large-scale resource utilization of carbide slag and fly ash, and enhances CO2 capture efficiency.
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Figure CN122164358A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon dioxide capture and resource utilization technology, specifically to a carbon dioxide adsorbent, its preparation method, and its application. Background Technology
[0002] Carbon dioxide capture, utilization, and storage (CCUS) is a key technology for achieving the "dual carbon" goal. Calcium recycling technology uses calcium-based adsorbents (such as carbide slag) to capture carbon dioxide through alternating carbonation and calcination reactions at high temperatures, offering advantages such as low cost and high activity.
[0003] Calcium carbide slag, a major byproduct of acetylene production, is high in calcium and exhibits rapid reactivity, making it an ideal raw material for calcium-based adsorbents. Current technologies typically utilize calcium carbide slag directly for high-temperature capture, or employ wet chemical modification (such as liquid-phase precipitation or spray drying), adding pure chemical reagents (such as nano-alumina, magnesium oxide, or zirconium oxide) as physical separators to inhibit calcium particle growth. Alternatively, pure alumina (Al₂O₃) can be used as a dopant modifier, followed by mechanical ball milling or mixing and calcination to form calcium aluminate (such as Ca²⁺) with high thermal stability. 12 Al 14 O 33 (or calcium silicate phase) to construct a framework support structure to prevent the aggregation of calcium oxide particles during high-temperature cycling.
[0004] However, existing methods still have many shortcomings: after multiple cycles, the internal pore structure of pure carbide slag adsorbents collapses and becomes blocked due to high-temperature sintering, leading to a sharp decrease in specific surface area, increased gas diffusion resistance, and a rapid decline in cyclic capture capacity. Although adding pure chemical reagents (such as high-purity alumina) can improve stability, these modifiers are relatively expensive, and the preparation process involves complex multi-step pretreatment (such as organic acid etching or liquid-phase synthesis), making it difficult to meet the low-cost requirements of large-scale industrial applications. Existing technologies typically use only single-component modification. Although aluminum components can form a stable framework, their ability to control the initial pore size distribution is limited. While silicon components can change pore characteristics, their contribution to improving cyclic adsorption capacity is small when used alone. Existing modification methods mostly focus on the treatment of single solid wastes, failing to achieve the synergistic high-value utilization of multiple bulk industrial solid wastes such as carbide slag and fly ash, and may generate secondary pollution or have high energy consumption during the treatment process.
[0005] Therefore, developing a low-cost, highly stable method for preparing carbon dioxide adsorbents that enables the synergistic resource utilization of various industrial solid wastes has become an urgent technical problem to be solved in this field. Summary of the Invention
[0006] This invention addresses the shortcomings of existing technologies by providing a carbon dioxide adsorbent with low preparation cost, high stability, and the ability to achieve synergistic effects on multi-component solid waste, as well as its preparation method.
[0007] Therefore, in a first aspect, the present invention provides a method for preparing a carbon dioxide adsorbent, comprising: Raw material pretreatment: The carbide slag and fly ash are screened and dried separately; Preparation of carbon dioxide adsorbent: Pretreated carbide slag and fly ash are dry-mixed in a mixing device at a mass ratio of (8~10):1 to obtain a mixture. The mixture is then placed in a high-temperature reactor and calcined at a constant temperature of 840℃~860℃ for 1h~3h to generate carbon dioxide adsorbent in situ. 12 Al 14 O 33 Carbon dioxide adsorbent for substances.
[0008] Furthermore, the chemical composition of the carbide slag, by mass fraction, includes: 75.0%~80.0% Ca(OH)2, 4.5%~6.0% SiO2, 2.0%~3.0% Al2O3, 0.5%~1.0% Na2O, 0.3%~0.6% Fe2O3, and 0.1%~0.5% MgO; The chemical composition of the fly ash, by mass fraction, includes: 2.5%~3.5% CaO, 38.0%~42.0% SiO2, 42.0%~50.0% Al2O3, 0.2%~0.4% Na2O, 1.0%~2.0% Fe2O3, and 0.3%~1.0% MgO.
[0009] Further, the screening process involves screening the carbide slag and the fly ash separately to a particle size of less than 200 mesh. The drying process involves placing the sieved carbide slag and fly ash separately in an oven at 100℃~150℃ for 10h~14h, then placing them in a muffle furnace and calcining them at 800℃~900℃ in air for 0.5h~1.5h, followed by cooling to room temperature at a rate of 20℃ / min~30℃ / min.
[0010] Furthermore, the calcination time is 100 min to 140 min.
[0011] Furthermore, the mass ratio of the pretreated carbide slag to fly ash is (8.8~9.2):1.
[0012] In a second aspect, the present invention provides a carbon dioxide adsorbent, which is prepared by the aforementioned preparation method.
[0013] Furthermore, the Ca in the carbon dioxide adsorbent 12 Al 14 O 33 The material is uniformly dispersed between CaO grains, and the CaO grains are physically isolated to form a thermally stable support framework.
[0014] A third aspect of the present invention provides an application of the aforementioned carbon dioxide adsorbent in carbon dioxide capture.
[0015] Furthermore, the carbon dioxide adsorbent is used for carbon dioxide capture at 650°C to 800°C.
[0016] Furthermore, after 20 cycles at 750°C, the carbonation conversion rate of the carbon dioxide adsorbent is increased by more than 22% compared to pure calcium carbide slag adsorbent, more than 7% compared to calcium carbide slag adsorbent mixed with alumina, and more than 13% compared to calcium carbide slag adsorbent mixed with silica.
[0017] Compared with the prior art, the present invention has at least the following beneficial effects: The carbon dioxide adsorbent provided by this invention involves dry mixing calcium carbide slag and fly ash, followed by high-temperature calcination. This causes a solid-phase reaction between the calcium component in the calcium carbide slag and the aluminum component in the fly ash, resulting in the in-situ directional generation of Ca. 12 Al 14 O 33 This substance does not participate in the carbonation reaction during the high-temperature cyclic reaction of carbon dioxide adsorption. It can form a stable mechanical support framework between CaO grains, effectively preventing the agglomeration and sintering of calcium oxide particles during high-temperature cycling. After 20 high-temperature adsorption-desorption cycles, it can still maintain a high specific surface area and porosity. The carbon dioxide adsorbent provided by this invention uses two industrial solid wastes, carbide slag and fly ash, as raw materials. It not only significantly reduces the cost of calcium recycling for CO2 capture, but also opens up a high-value-added path for the large-scale resource utilization of carbide slag and fly ash. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0019] Figure 1 The following are temperature-varying and isothermal adsorption curves of four adsorbents provided in the embodiments of the present invention, wherein... Figure 1 a is the CO2 adsorption rate diagram under varying temperature adsorption conditions. Figure 1 b is the CO2 adsorption rate diagram under varying temperature conditions. Figure 1c is the CO2 adsorption capacity diagram at a constant temperature of 650℃. Figure 1 d is the CO2 adsorption capacity diagram at a constant temperature of 700℃. Figure 1 e is a graph showing the CO2 adsorption capacity at a constant temperature of 750℃. Figure 1 f is a graph showing the CO2 adsorption capacity at a constant temperature of 800℃; Figure 2 The following are cycle stability test graphs of four adsorbents provided in the embodiments of the present invention. The left graph shows the relationship between the number of cycles and the adsorption amount of the four adsorbents, and the right graph shows the relationship between the number of cycles and the carbonation conversion rate of the four adsorbents. Figure 3 Microscopic characterization of four adsorbents provided in embodiments of the present invention at different cycle numbers, wherein, Figure 3 a represents the phase diagrams of pure carbide slag (C) before adsorption, after 5 cycles, after 10 cycles, and after 20 cycles. Figure 3 b shows the phase diagrams of carbide slag / fly ash (CF) before adsorption, after 5 cycles, after 10 cycles, and after 20 cycles. Figure 3 c represents the phase diagrams of carbide slag / alumina (CAL) before adsorption, after 5 cycles, after 10 cycles, and after 20 cycles. Figure 3 d represents the phase diagrams of carbide slag / silica (CSI) before adsorption, after 5 cycles, after 10 cycles, and after 20 cycles. Figure 4 These are electron microscope images of the four adsorbents provided in the embodiments of the present invention before 20 cycles; Figure 5 These are electron microscope images of the four adsorbents provided in the embodiments of the present invention after 20 cycles; Figure 6 The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of four adsorbents provided in the embodiments of the present invention are as follows: Figure 6 a is a pore size diagram of pure carbide slag (C) before and after 20 cycles. Figure 6 b shows the pore size diagram of carbide slag / fly ash (CF) before and after 20 cycles. Figure 6 c represents the pore size diagram of carbide slag / alumina (CAL) before and after 20 cycles. Figure 6 d shows the pore size diagram before and after 20 cycles of carbide slag / silica (CSI). Figure 6 e represents the pore size diagram of the four adsorbents in their initial state. Figure 6 f is the pore size diagram of the four adsorbents after 20 cycles; Figure 7 The adsorption performance diagrams of carbon dioxide adsorbents prepared at different calcination temperatures are provided for embodiments of the present invention. Figure 8 The graph shows the CO2 adsorption rate of calcium carbide slag and fly ash in the carbon dioxide adsorbent provided in the embodiments of the present invention during isothermal adsorption at different mass ratios. Detailed Implementation
[0020] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.
[0021] A first aspect of this invention provides a method for preparing a carbon dioxide adsorbent, comprising: Raw material pretreatment: The carbide slag and fly ash are screened and dried separately; Preparation of carbon dioxide adsorbent: Pretreated carbide slag and fly ash are dry-mixed in a mixing device at a mass ratio of (8~10):1 to obtain a mixture. The mixture is then placed in a high-temperature reactor and calcined at a constant temperature of 840℃~860℃ for 1h~3h to generate carbon dioxide adsorbent in situ. 12 Al 14 O 33 Carbon dioxide adsorbent for substances.
[0022] This invention changes the existing methods that use high-purity chemical reagents or single solid waste. By utilizing the high alumina and silicon content of fly ash, it mixes it with carbide slag in a specific ratio. The natural alumina and silicon oxide in fly ash are used as multi-component modification sources to construct a more stable multiphase composite support framework inside the adsorbent than a single component. This can effectively reduce the preparation cost of modified calcium-based adsorbents, realize the replacement of expensive high-purity chemical modification reagents with inexpensive industrial solid waste, and open up a high-value path for the large-scale resource utilization of carbide slag and fly ash.
[0023] Specifically, the mixture was calcined at 750℃, 850℃, and 950℃ respectively to obtain the corresponding carbon dioxide adsorbents. Then, isothermal adsorption experiments were conducted on the carbon dioxide adsorbents, such as... Figure 7 As shown, the adsorbents prepared at 850℃ and 950℃ have better adsorption effects, but from the perspective of energy saving, the preferred temperature for constant temperature calcination is 850℃, and the preferred calcination time is 2h.
[0024] In some embodiments, the chemical composition of carbide slag, by mass fraction, includes: 75.0%~80.0% Ca(OH)2, 4.5%~6.0% SiO2, 2.0%~3.0% Al2O3, 0.5%~1.0% Na2O, 0.3%~0.6% Fe2O3, and 0.1%~0.5% MgO; The chemical composition of fly ash, by mass fraction, includes: 2.5%~3.5% CaO, 38.0%~42.0% SiO2, 42.0%~50.0% Al2O3, 0.2%~0.4% Na2O, 1.0%~2.0% Fe2O3, and 0.3%~1.0% MgO.
[0025] The preferred chemical composition of carbide slag is: 78.65% Ca(OH)2, 5.30% SiO2, 2.48% Al2O3, 0.72% Na2O, 0.53% Fe2O3, and 0.30% MgO. The preferred chemical composition of fly ash is: 3.03% CaO, 40.48% SiO2, 46.12% Al2O3, 0.32% Na2O, 1.49% Fe2O3, and 0.67% MgO.
[0026] In some embodiments, the sieving process involves sieving the carbide slag and fly ash separately to a particle size of less than 200 mesh. The drying process involves placing the sieved carbide slag and fly ash separately in an oven at 100℃~150℃ for 10h~14h, then placing them in a muffle furnace and calcining them at 800℃~900℃ in air for 0.5h~1.5h, followed by cooling to room temperature at a rate of 20℃ / min~30℃ / min.
[0027] Preferably, drying is carried out in an oven at 120°C for 12 hours.
[0028] The preferred calcination temperature in the muffle furnace is 850℃, the preferred calcination time is 1h, and the preferred cooling rate is 25℃ / min.
[0029] In some embodiments, the calcination time is 100 min to 140 min.
[0030] During calcination, the calcination temperature of the mixture is precisely controlled at 850℃. Within this specific temperature range, the activity of CaO is ensured, and a solid-phase reaction is induced between the aluminum component in the fly ash and the calcium component released from the decomposition of carbide slag, resulting in the in-situ directional generation of CaO. 12 Al 14 O 33 The new phase exhibits the best adsorption performance and cycle stability.
[0031] In some embodiments, the mass ratio of pretreated carbide slag to fly ash is (8.8~9.2):1.
[0032] The preferred mass ratio of calcium carbide slag to fly ash is 9:1.
[0033] Isothermal adsorption experiments were conducted on samples with four mass ratios of calcium carbide slag to fly ash: 95:5, 9:1, 8:2, and 7:3, respectively. Figure 8 As shown, the adsorption capacity of the samples was lower at mass ratios of 8:2 and 7:3, while it was higher at 95:5 and 9:1, and the adsorption capacity of 95:5 and 9:1 was not significantly different. Therefore, considering both the full utilization of solid waste and the high CO2 capture rate, a mass ratio of 9:1 was ultimately selected.
[0034] In a second aspect, the present invention provides a carbon dioxide adsorbent, which is prepared by the above-described preparation method.
[0035] In some embodiments, the Ca in the carbon dioxide adsorbent 12 Al 14 O 33 The material is uniformly dispersed between CaO grains, physically isolating the CaO grains to form a thermally stable support framework.
[0036] Specifically, due to Ca 12 Al 14 O 33 The substance does not participate in the carbonation reaction during the high-temperature cyclic reaction, thus physically isolating the CaO grains and preventing grain growth and caking caused by high-temperature sintering during multiple "adsorption-desorption" cycles.
[0037] A third aspect of the present invention provides an application of a carbon dioxide adsorbent in carbon dioxide capture.
[0038] In some embodiments, the above-described carbon dioxide adsorbent is used for carbon dioxide capture at 650°C to 800°C.
[0039] In some embodiments, after 20 cycles at 750°C, the carbonation conversion rate of the above-mentioned carbon dioxide adsorbent is increased by more than 22% compared with pure calcium carbide slag adsorbent, more than 7% compared with calcium carbide slag adsorbent mixed with alumina, and more than 13% compared with calcium carbide slag adsorbent mixed with silica.
[0040] Based on Ca 12 Al 14 O 33 The support provided by the skeleton allows the adsorbent to maintain a high specific surface area and porosity even after 20 high-temperature adsorption-desorption cycles.
[0041] Compared with single doping (alumina or silica), multi-component modification of fly ash can construct a better hierarchical porous structure. Calculations using the double exponential model have shown that this structure reduces the diffusion resistance of CO2 inside the adsorbent, allowing the reaction rate to reach its peak at 750℃. After 20 cycles, the carbonation conversion rate is significantly improved compared with other adsorbents.
[0042] The optimal adsorption operating temperature of 750℃ was confirmed, providing a scientific theoretical basis for the temperature control parameter setting of subsequent industrial-scale collection equipment and ensuring that the adsorbent can exert its maximum efficiency under actual working conditions.
[0043] Example 1: Preparation and Performance Evaluation of Calcium Carbide Slag / Fly Ash Adsorbent (I) Preparation method Includes the following steps: The chemical composition of the carbide slag used in the experiment, by mass fraction, includes: 78.65% Ca(OH)2, 5.30% SiO2, 2.48% Al2O3, 0.72% Na2O, 0.53% Fe2O3, and 0.30% MgO; The chemical composition of the fly ash used, by mass fraction, includes: 3.03% CaO, 40.48% SiO2, 46.12% Al2O3, 0.32% Na2O, 1.49% Fe2O3, and 0.67% MgO.
[0044] (1) Raw material pretreatment: After screening the carbide slag and fly ash to a particle size of less than 200 mesh, the carbide slag and fly ash were transferred to clean and dry beakers and dried in an oven at 120℃ for 12 hours. In order to completely remove residual moisture, the dried carbide slag and fly ash were placed in a muffle furnace and calcined at 850℃ for 1 hour in air atmosphere, and then cooled to room temperature at a rate of 25℃ / min.
[0045] (2) Preparation of adsorbent: The pretreated carbide slag and fly ash were weighed at a mass ratio of 9:1. The two raw materials were placed in a mixing device for thorough dry mixing to ensure that the fly ash particles were evenly distributed in the carbide slag matrix. The uniformly mixed sample was placed in a high-temperature reactor and calcined at 850℃ for 2 hours to obtain the carbide slag / fly ash adsorbent, denoted as "CF".
[0046] (ii) Performance Evaluation (1) Temperature-switching adsorption experiment: The prepared adsorbent was placed in a thermogravimetric reactor and heated linearly from room temperature to 900℃ at a rate of 10℃ / min under a CO2 atmosphere. The change of adsorption amount with temperature was monitored in real time.
[0047] (2) Isothermal adsorption experiment: The prepared adsorbent was subjected to isothermal adsorption performance tests at four temperature gradients of 650℃, 700℃, 750℃ and 800℃.
[0048] (3) Cyclic stability test: The prepared adsorbent was subjected to 20 adsorption-desorption cycles.
[0049] The formula for carbonation conversion rate is as follows:
[0050] The carbonation conversion rate after N cycles is expressed in % (%). This represents the initial mass of the adsorbent, expressed in grams. This represents the mass of the sample after carbonation at time t following the Nth cycle, in grams. The mass of the sample after complete calcination in the Nth cycle is expressed in g. The percentage of CaO in the initial adsorbent, expressed in wt.%; and This represents the molecular weight of CaO and CO2.
[0051] (4) Calculation of kinetic rate: The adsorption process at different temperatures is kinetically fitted by a double exponential model, and the adsorption rate constant is calculated.
[0052] Comparative Example 1: Preparation of Pure Calcium Carbide Slag Adsorbent Unlike Example 1, the preparation method does not involve the addition of fly ash, resulting in a pure carbide slag adsorbent, denoted as "C".
[0053] Comparative Example 2: Preparation of Alumina-doped Adsorbent from Calcium Carbide Slag Unlike Example 1, in the preparation method, fly ash is replaced with alumina to obtain carbide slag-doped alumina adsorbent, denoted as "CAL".
[0054] The alumina used in the experiment was reagent grade, ≥99%, A800193-500g, batch number: C15217198, CAS: 1344-28-1, purchased from Shanghai Maclean Biochemical Co., Ltd. (Shanghai, China), and was in powder form.
[0055] Comparative Example 3: Preparation of Silica-Doped Adsorbent from Calcium Carbide Slag Unlike Example 1, in the preparation method, fly ash is replaced with silicon dioxide to obtain carbide slag-doped silicon dioxide adsorbent, denoted as "CSI".
[0056] The silica used in the experiment was analytical grade, 250g, batch number 20231215, purchased in December 2023, CAS: 7631-86-9, in powder form.
[0057] Results analysis: like Figure 1 As shown in Figure a, the adsorption capacity of all four adsorbents increased with increasing temperature. Among them, C, CF, and CAL showed better performance, while silicon-doped (CSI) showed poorer performance, and the optimal adsorption temperature range was 650℃~800℃.
[0058] like Figure 1 As shown in b, within the adsorption temperature range, among the four adsorbents, C and CF have the fastest adsorption rates as the temperature increases.
[0059] because Figure 1 The optimal adsorption temperature range for a is 650℃~800℃, therefore, isothermal adsorption was performed at 650℃, 700℃, 750℃, and 800℃ respectively. Figure 1 As shown in Figure c, at 650℃, except for carbide slag (C), the adsorption capacity of other adsorbents continued to increase with rising temperature, but did not reach the maximum adsorption capacity; for example... Figure 1 As shown in Figure d, at 700℃, other adsorbents still did not reach their maximum adsorption capacity; for example... Figure 1 As shown in Figure e, at 750℃, all four adsorbents exhibit a tendency to level off; for example... Figure 1 As shown in f, at 800℃, the four adsorbent samples showed almost no adsorption. Therefore, 750℃ was ultimately selected as the optimal adsorption temperature, and all subsequent experiments were conducted at 750℃.
[0060] like Figure 2 As shown in the left figure, the adsorption capacity of all four adsorbent samples decreased with increasing cycle number. This is because the adsorbents begin to sinter with increasing adsorption cycles, resulting in less porous material, smaller specific surface area, and poorer adsorption capacity. However, it can be seen that after 20 cycles, CF showed the lowest decrease rate, indicating that CF has the best anti-sintering effect. Figure 2 As shown in the right figure, the carbonation conversion rate from CaO to CaCO3 decreases with increasing cycle number, indicating a deteriorating adsorption effect. After 20 cycles, the carbonation conversion rate of CF (43.21%) was more than 22% higher than that of C (20.34%), more than 7% higher than that of CAL (35.93%), and more than 13% higher than that of CSI (29.90%), further demonstrating that CF has the best anti-sintering effect.
[0061] To further illustrate the experimental results above, microscopic characterization of the materials was conducted. For example... Figure 3 As shown in Figure a, as the adsorption process proceeds, CaO and Ca(OH)2 are gradually consumed, while CaCO3 is continuously generated; as shown in Figure a... Figure 3 As shown in b, CF generates a new substance—calcium aluminate Ca—as the adsorption process proceeds. 12 Al 14 O 33 This material has a high Taman temperature and will not collapse even after repeated calcination at high temperatures. Other literature has shown that it can act as a support structure, thus explaining the experimental phenomenon described above—CF exhibits the best cycling effect. For example... Figure 3 As shown in c, CAL also forms calcium aluminate Ca.12 Al 14 O 33 Therefore, in the above adsorption experiments, the aluminum-doped samples also exhibited good adsorption capacity; such as Figure 3 As shown in d, CSI forms silicates during the adsorption-desorption cycle. Since silicates cannot act as a framework, and the newly generated substances occupy the effective active sites of calcium, the adsorption performance is poor.
[0062] like Figure 4 and Figure 5 As shown in the diagrams, comparing the graphs before and after each adsorbent cycle, C20 shows obvious agglomeration and compaction compared to C20, while C has more pores. Compared to CAL20, CAL20 shows less agglomeration than C, but CAL20 has some narrow cracks after agglomeration, thus its adsorption effect is higher than that of C20. Compared to CF20, CF shows some agglomeration, but compared to C20 and CAL20, it has more pores and smaller agglomerates, thus its adsorption effect is the best.
[0063] The pore structure of carbide slag doped with different additives was characterized by nitrogen isothermal adsorption-desorption tests, and the results are as follows: Figure 6 As shown in Table 1.
[0064] Table 1. Pore size distribution of the four adsorbents before and after 20 cycles.
[0065] According to the classification of the International Union of Pure and Applied Chemistry (IUPAC), all samples exhibited type IV isotherms accompanied by type H3 hysteresis loops, which is due to capillary aggregation in the mesopores. The pore structure of the adsorbent is mainly mesoporous, and its pore shape is usually characterized by disordered slit-like pores formed by the stacking of plates or particles.
[0066] like Figure 6 As shown, before cycling, samples C and CSI had a higher proportion of pores in the 2nm-10nm range, while having fewer pores larger than 10nm. In contrast, samples CAL and CF had fewer micropores and more macropores. After 20 cycles, samples CF20 and CAL20 showed higher micropore counts and porosity than samples C20 and CSI20, which is beneficial for CO2 diffusion and mass transfer in the adsorbent.
[0067] The specific surface area and pore structure parameters of different adsorbents are listed in Table 1. Compared with sample C, the modified adsorbents showed increased specific surface area and pore volume, with sample CAL exhibiting the largest specific surface area. Samples CF and C had smaller average pore sizes, indicating that they possess mesoporous structures favorable for CO2 adsorption. In contrast, sample CSI had a larger average pore size and a more open pore structure, resulting in a lower initial adsorption capacity.
[0068] In a thermogravimetric reactor, with a temperature range of 650℃ to 750℃ and an atmosphere of 20% CO2 / 80% N2, the carbonation reaction rate was studied using thermogravimetric analysis (TGA), and a bi-exponential model was selected as the fitting model. This model can describe the two stages of the carbonation process: a rapid chemical reaction adsorption stage (surface-controlled) and a slower product diffusion stage (pore diffusion-limited).
[0069] The experimental data of four groups of original samples (C, CF, CAL, CSI) under adsorption conditions of 650℃, 700℃ and 750℃ were fitted to determine the optimal reaction temperature. The results are shown in Table 2.
[0070] Table 2 Calculation of the double exponential model
[0071] The results show that all fits have high goodness of fit (R0). 2 The applicability of the double-exponential model was verified by the k1 value being ≥0.991. Furthermore, k1 was significantly larger than k2 in all samples, indicating that the rapid chemisorption phase dominated, while diffusion limitation only gradually appeared in the later stages of the reaction. All adsorbent samples exhibited the highest reaction rate at 750 °C, thus confirming this temperature as the optimal carbonation temperature.
[0072] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments 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 technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.
Claims
1. A method for preparing a carbon dioxide adsorbent, characterized in that, include: Raw material pretreatment: The carbide slag and fly ash are screened and dried separately; Preparation of carbon dioxide adsorbent: Pretreated carbide slag and fly ash are dry-mixed in a mixing device at a mass ratio of (8~10):1 to obtain a mixture. The mixture is then placed in a high-temperature reactor and calcined at a constant temperature of 840℃~860℃ for 1h~3h to generate carbon dioxide adsorbent in situ. 12 Al 14 O 33 Carbon dioxide adsorbent for substances.
2. The preparation method according to claim 1, characterized in that, The chemical composition of the carbide slag, by mass fraction, includes: 75.0%~80.0% Ca(OH)2, 4.5%~6.0% SiO2, 2.0%~3.0% Al2O3, 0.5%~1.0% Na2O, 0.3%~0.6% Fe2O3, and 0.1%~0.5% MgO; The chemical composition of the fly ash, by mass fraction, includes: 2.5%~3.5% CaO, 38.0%~42.0% SiO2, 42.0%~50.0% Al2O3, 0.2%~0.4% Na2O, 1.0%~2.0% Fe2O3, and 0.3%~1.0% MgO.
3. The preparation method according to claim 1, characterized in that, The screening process involves screening the carbide slag and the fly ash separately to a particle size of less than 200 mesh. The drying process involves placing the sieved carbide slag and fly ash separately in an oven at 100℃~150℃ for 10h~14h, then placing them in a muffle furnace and calcining them at 800℃~900℃ in air for 0.5h~1.5h, followed by cooling to room temperature at a rate of 20℃ / min~30℃ / min.
4. The preparation method according to claim 1, characterized in that, The calcination time is 100 min to 140 min.
5. The preparation method according to claim 1, characterized in that, The mass ratio of the pretreated carbide slag to fly ash is (8.8~9.2):
1.
6. A carbon dioxide adsorbent, characterized in that, The carbon dioxide adsorbent is prepared by the preparation method according to any one of claims 1-5.
7. The carbon dioxide adsorbent according to claim 6, characterized in that, The Ca in the carbon dioxide adsorbent 12 Al 14 O 33 The material is uniformly dispersed between CaO grains, and the CaO grains are physically isolated to form a thermally stable support framework.
8. The application of the carbon dioxide adsorbent according to claim 6 or 7 in carbon dioxide capture.
9. The application according to claim 8, characterized in that, The carbon dioxide adsorbent is used for carbon dioxide capture at temperatures ranging from 650°C to 800°C.
10. The application according to claim 8 or 9, characterized in that, After 20 cycles at 750℃, the carbon dioxide adsorbent's carbonation conversion rate is more than 22% higher than that of pure carbide slag adsorbent, more than 7% higher than that of carbide slag adsorbent mixed with alumina, and more than 13% higher than that of carbide slag adsorbent mixed with silica.