A method for evaluating the performance of porous carbon materials in capturing CO2

Abstract

This invention discloses a method for evaluating the performance of porous carbon materials in capturing CO2, comprising: obtaining the specific surface area, pore volume, and average pore diameter of the porous carbon material; conducting CO2 adsorption experiments under different pressure and temperature conditions, and recording the pressure, temperature, and CO2 adsorption amount during CO2 capture by the porous carbon material; performing multivariate regression using a dichotomy method and fitting the regression curve to determine the weight ratios θ1, θ2, θ3, θ4, and θ5 of the specific surface area, pore volume, average pore diameter, pressure, and temperature of the porous carbon material on the CO2 adsorption effect; and calculating the comprehensive evaluation index δ. This method for evaluating the performance of porous carbon materials in capturing CO2 can comprehensively and effectively evaluate the CO2 adsorption performance of porous carbon materials, thereby accurately measuring the CO2 capture effect of porous carbon materials. It can provide a theoretical basis and data support for optimizing the preparation process of porous carbon materials and improving their adsorption efficiency.

Description

Technical Field

[0001] This invention relates to a material performance evaluation method, specifically a performance evaluation method for capturing CO2 using porous carbon materials, belonging to the field of CO2 capture technology. Background Technology

[0002] With the rapid development of modern industry, CO2 emissions are constantly increasing, causing serious environmental impacts such as global warming, sea-level rise, and ecosystem destruction. Therefore, developing efficient CO2 capture materials has become an important research direction. Currently, the research focus of adsorption-based CO2 capture technology is on adsorbents and adsorption processes, with adsorbents being of paramount importance. An ideal CO2 adsorbent should possess characteristics such as high adsorption capacity, fast adsorption rate, high selectivity for CO2, low cost, simple preparation method, excellent cyclic adsorption performance, and strong tolerance to moisture and other impurities. Porous carbon materials, namely carbon-based materials with high specific surface area and abundant pore structure, provide a large number of adsorption sites and rapid diffusion channels for CO2 due to their high porosity, surface area, and suitable pore size, thus ensuring efficient adsorption capacity and selectivity. This characteristic makes porous carbon materials promising for widespread application in CO2 capture and storage, especially in power plants, oil refineries, and other locations that generate large amounts of CO2. Coal gasification slag is an industrial waste with abundant carbonaceous components and a complex chemical structure. After being processed through specific processes, coal gasification slag can be transformed into porous carbon materials with high specific surface area and porous characteristics.

[0003] To evaluate the CO2 adsorption performance of porous carbon materials, specialized evaluation methods are typically required. Commonly used evaluation indicators include specific surface area, pore volume, pore size distribution, and pore morphology. Specific surface area is the total surface area per unit mass of a substance. Materials with larger specific surface areas provide more reaction and adsorption sites, resulting in more significant surface effects such as surface activity, surface adsorption capacity, and catalytic activity. Pore volume is the total volume of pores per unit mass or volume of material. In applications such as catalysis, drug delivery, energy storage, and conversion, pore volume directly relates to the material's storage capacity and mass transport efficiency. Pore size distribution refers to the variation or distribution of pore volume with pore size; this characterization indicator is helpful in determining the applicability of porous powders. Pore morphology refers to the geometry, connectivity, and arrangement of pores within or on the surface of a material, and it also significantly influences the adsorption, filtration, storage, and catalytic properties of porous carbon materials.

[0004] However, existing methods for evaluating the CO2 adsorption performance of porous carbon materials mostly focus on a single indicator, such as specific surface area or pore volume. There is no comprehensive and effective evaluation method to assess and optimize the CO2 adsorption performance of porous carbon materials under different pressure and temperature conditions. Researchers and developers cannot accurately measure the CO2 capture effect of porous carbon materials, and cannot determine whether the performance of porous carbon materials has met expectations. This is a problem that urgently needs to be solved in the industry. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for evaluating the performance of porous carbon materials in capturing CO2. This method can comprehensively and effectively evaluate the adsorption performance of porous carbon materials for CO2, thereby accurately measuring the CO2 capture effect of porous carbon materials. It can provide a theoretical basis and data support for optimizing the preparation process of porous carbon materials and improving their adsorption efficiency.

[0006] To achieve the above objectives, the performance evaluation method for CO2 capture using porous carbon materials specifically includes the following steps:

[0007] Step 1: Obtain the specific surface area, pore volume, and average pore diameter of the porous carbon material.

[0008] Step 2: Conduct CO2 adsorption experiments under different pressure and temperature conditions, and record the pressure, temperature and CO2 adsorption amount when the porous carbon material captures CO2.

[0009] Step 3: Based on the data from Step 1 and Step 2, perform multivariate regression using the dichotomy method and fit the regression curve to determine the weight ratios θ1, θ2, θ3, θ4, and θ5 of the specific surface area, pore volume, average pore size, pressure, and temperature of the porous carbon material on the CO2 adsorption effect.

[0010] Step 4: Calculate the comprehensive evaluation index δ. The larger the comprehensive evaluation index δ, the better the CO2 adsorption effect. The specific calculation formula is as follows:

[0011] δ=θ1×S+θ2×V+θ3×P+θ4×T+θ5×d+α

[0012] In the formula: S is the specific surface area, in m². 2 / kg; V is the pore volume, in cm³. 3 / kg; P is pressure, in kPa; T is temperature, in °C; d is average pore size, in nm; α is correction factor.

[0013] Furthermore, the formula for calculating the correction factor α in Step 4 is as follows:

[0014] α = β × (specific surface area / pore volume) × average pore diameter

[0015] In the formula: β is a constant.

[0016] Furthermore, in Step 3, when performing multiple regression using the bisection method and fitting the regression curve, the regression curve is fitted and the fitting error is calculated. If the fitting error meets the preset accuracy requirements, the curve is determined to be the best-fit curve; otherwise, the fitting parameters are adjusted, and the regression curve is fitted and the fitting error is calculated repeatedly until the fitting error meets the accuracy requirements.

[0017] Furthermore, in Step 1, the specific surface area and pore volume are determined by nitrogen adsorption-desorption isotherms, the specific surface area is calculated using the BET method, and the pore volume and average pore diameter are calculated using the BJH method.

[0018] Furthermore, when calculating specific surface area using the BET method, the BET formula is as follows:

[0019]

[0020] In the formula: V is the amount of nitrogen adsorbed, V m P is the monolayer adsorption capacity, P is the partial pressure of nitrogen, P0 is the saturated vapor pressure of nitrogen, and C is the BET constant.

[0021] Based on the adsorption isotherm data, select an appropriate relative pressure range and calculate the pressure for each data point. and Then, a linear fit was performed, and the monolayer adsorption capacity V was calculated by using the slope and intercept of the fitted line. m and the BET constant C;

[0022] The formula for calculating specific surface area is as follows:

[0023]

[0024] In the formula: S is the specific surface area, N is Avogadro's constant, σ is the cross-sectional area of ​​nitrogen molecules, and m is the mass of the sample.

[0025] Furthermore, when calculating the pore volume and average pore size using the BJH method, data points from adsorption or desorption isotherms are selected and arranged in order of decreasing pressure. The pore size D corresponding to each data point is then calculated using the Kelvin equation.

[0026]

[0027] In the formula: γ is the surface tension of nitrogen, θ is the contact angle, R is the gas constant, ρ is the density of nitrogen, P is the partial pressure of nitrogen, and P0 is the saturated vapor pressure of nitrogen.

[0028] The average aperture d is calculated using the following formula:

[0029]

[0030] In the formula: n is the number of apertures;

[0031] Calculate the pore volume increment ΔV for each pore diameter:

[0032] ΔV=V ads (P i )-V ads (P i+1 )

[0033] In the formula: V ads (P i ) and V ads (P i+1 ) represent the adsorption amounts of the i-th and i+1-th data points, respectively;

[0034] Calculate the sum of the pore volume increments V corresponding to all pore diameters. total :

[0035] V total =∑ΔV.

[0036] Furthermore, in Step 2, the selection of different pressure and temperature conditions is based on the changing trend of the adsorption performance of porous carbon materials under different pressure and temperature conditions. The specific pressure and temperature conditions are selected according to experimental requirements and the characteristics of porous carbon materials.

[0037] Furthermore, for porous carbon materials prepared by different preparation processes, the optimal preparation process for porous carbon materials is selected based on the calculation results of the comprehensive evaluation index δ.

[0038] Furthermore, for porous carbon materials with different pressures and temperatures, the optimal pressure and temperature operating environment is selected based on the calculation results of the comprehensive evaluation index δ to be applied to the adsorption of CO2 by porous carbon materials.

[0039] Furthermore, the porous carbon material is prepared from coal gasification slag.

[0040] Compared with existing technologies, the performance evaluation method for CO2 capture using porous carbon materials presented in this paper has the following advantages:

[0041] 1. This method for evaluating the CO2 capture performance of porous carbon materials comprehensively considers five key factors: specific surface area, pore volume, average pore size, pressure, and temperature. It establishes a more comprehensive evaluation system that can more accurately reflect the adsorption performance of porous carbon materials under different conditions.

[0042] 2. Porous carbon materials prepared from coal gasification slag possess unique physicochemical properties. Existing evaluation methods for porous carbon materials are not entirely applicable to them. This performance evaluation method for CO2 capture by porous carbon materials fully considers the characteristics of porous carbon materials prepared from coal gasification slag, enabling a more accurate assessment of their adsorption performance. It can provide a theoretical basis and data support for the efficient utilization of coal gasification slag, not only reducing the amount of coal gasification slag landfill and lowering environmental pollution, but also promoting the application of environmentally friendly materials in the field of CO2 capture, resulting in considerable environmental benefits.

[0043] 3. The performance evaluation method for CO2 capture by porous carbon materials can provide a scientific basis for production decisions of porous carbon materials, help optimize the production process of porous carbon materials, improve the product quality of porous carbon materials, and also help accelerate the industrialization process of CO2 capture technology of porous carbon materials in coal gasification slag, and promote the development of related industries. Attached Figure Description

[0044] Figure 1 This is a flowchart of the present invention;

[0045] Figure 2 This is a comparison chart of CO2 adsorption capacity of sample 1 in embodiment of the present invention under a temperature environment of 25°C and under different pressure conditions;

[0046] Figure 3 This is a comparison chart of CO2 adsorption capacity of samples 1 to 9 in the embodiments of the present invention under a temperature environment of 25°C and a pressure of 100kPa.

[0047] Figure 4 This is a comparison chart of the comprehensive evaluation index δ of samples 1 to 5 of the present invention under 100 kPa pressure and different temperature conditions;

[0048] Figure 5 This is a radar chart showing the weighted ratios of specific surface area, pore volume, average pore diameter, temperature, and pressure in an embodiment of the present invention. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings, taking porous carbon materials prepared from coal gasification slag as an example.

[0050] like Figure 1As shown, the performance evaluation method for CO2 capture using porous carbon materials first obtains the specific surface area, pore volume, and average pore diameter of the porous carbon material; then, it collects adsorption data by combining CO2 adsorption experiments under different pressure and temperature conditions; next, it uses a bisection method to find the best fitting curve, which reflects the influence of pressure and temperature on adsorption performance, thereby determining the weight ratio at different pressures and temperatures. Finally, these weights are used to calculate the comprehensive evaluation index δ, thereby evaluating the CO2 adsorption capacity of the porous carbon material under actual working conditions. The details are as follows:

[0051] Step 1: Obtain the specific surface area, pore volume, and average pore diameter of the porous carbon material. The specific surface area and pore volume were determined by nitrogen adsorption-desorption isotherms. The specific surface area was calculated using the BET method, and the pore volume and average pore diameter were calculated using the BJH method.

[0052] The BET method was used to calculate the specific surface area of ​​porous carbon materials: Based on multilayer adsorption theory, the BET method calculates the specific surface area of ​​a sample by measuring the amount of nitrogen adsorbed on the sample surface. Details are as follows:

[0053] a. Pretreatment of porous carbon material samples at 200℃ and a vacuum degree of 10 -3 ~10 -5 The sample was treated at Pa for 10 hours to remove impurities (such as water molecules, other volatile substances, etc.) adsorbed on the sample surface.

[0054] b. Nitrogen (N2) was chosen as the adsorbate gas because it is chemically inert, readily available, and has suitable adsorption characteristics at liquid nitrogen temperature (77K).

[0055] c. Place the pretreated sample into the adsorbent apparatus. At 77 K, gradually increase the relative pressure of the adsorbate gas (P / P0, where P is the actual adsorption pressure and P0 is the saturated vapor pressure of the adsorbate at that temperature). Measure the amount of adsorbate adsorbed on the sample surface (V) at different relative pressures using the gravimetric method (measuring the weight change of the sample after adsorption).

[0056] d. Calculate using the BET equation:

[0057]

[0058] In the formula: V is the amount of nitrogen adsorbed, V m denoted as monolayer adsorption capacity, P as partial pressure of nitrogen, P0 as saturated vapor pressure of nitrogen, and C as BET constant.

[0059] Based on the adsorption isotherm data, select an appropriate relative pressure range (usually 0.05–0.35) and calculate the relative pressure for each data point. and Then, a linear fit was performed, and the monolayer adsorption capacity V was calculated by using the slope and intercept of the fitted line. m And the BET constant C.

[0060] e. Specific surface area calculation:

[0061]

[0062] In the formula: S is the specific surface area, N is Avogadro's constant, and σ is the cross-sectional area of ​​a nitrogen molecule (taken as 0.162 nm). 2 ), where m is the mass of the sample.

[0063] The BJH method was used to calculate the pore volume and average pore size of porous carbon materials. Based on the Kelvin equation, the BJH method uses nitrogen adsorption-desorption isotherm data to calculate the pore size distribution and pore volume of porous carbon materials. The BJH method assumes that the pores are rigid and have a regular shape (e.g., cylindrical). Data points from adsorption or desorption isotherms are selected and arranged in order of decreasing pressure. Details are as follows:

[0064] a. Obtain representative samples from porous carbon material samples and perform necessary pretreatment, such as grinding and sieving, to obtain a suitable particle size for testing. Then, dry the representative samples to remove moisture and volatile substances.

[0065] b. Place the pretreated sample in the adsorption apparatus and conduct an adsorption experiment at a constant temperature of 77K. Gradually increase the relative pressure of the adsorbate gas (P / P0, where P is the actual adsorption pressure and P0 is the saturated vapor pressure of the adsorbate at that temperature), and record the adsorption amount of the sample under different pressures. Record the adsorption isotherm data, including the relative pressure P / P0 and the corresponding adsorption amount V.

[0066] c. Plot the adsorption isotherm with relative pressure P / P0 on the x-axis and adsorption amount V on the y-axis.

[0067] d. Based on the adsorption isotherm data, the BJH model is applied for data processing, and the pore size D corresponding to each data point is calculated according to the Kelvin equation:

[0068]

[0069] In the formula: γ is the surface tension of nitrogen, θ is the contact angle, R is the gas constant, ρ is the density of nitrogen, P is the partial pressure of nitrogen, and P0 is the saturated vapor pressure of nitrogen.

[0070] The average aperture d is calculated using the following formula:

[0071]

[0072] In the formula: n is the number of apertures.

[0073] Calculate the pore volume increment ΔV for each pore diameter:

[0074] ΔV=V ads (P i )-V ads (P i+1 )

[0075] In the formula: V ads (P i ) and V ads (P i+1 ) represent the adsorption amounts of the i-th and i+1-th data points, respectively.

[0076] Calculate the sum of the pore volume increments V corresponding to all pore diameters. total :

[0077] V total =∑ΔV.

[0078] Step 2: Conduct CO2 adsorption experiments under different pressure and temperature conditions, and record the pressure, temperature, and CO2 adsorption amount when the porous carbon material captures CO2. The selection of different pressure and temperature conditions is based on the changing trend of the adsorption performance of the porous carbon material under different pressure and temperature conditions. The specific pressure and temperature conditions are selected according to the experimental requirements and the characteristics of the porous carbon material.

[0079] Step 3: Based on the adsorption data from the adsorption experiment, perform multivariate regression using the dichotomy method to find the best fitting curve and determine the weight ratios θ1, θ2, θ3, θ4, and θ5 of the specific surface area, pore volume, average pore diameter, pressure, and temperature of the porous carbon material for the CO2 adsorption effect.

[0080] When searching for the best-fitting curve, the regression curve is fitted and the fitting error is calculated. If the fitting error meets the preset accuracy requirements, the curve is determined to be the best-fitting curve; otherwise, the fitting parameters are adjusted, the regression curve is fitted and the fitting error is calculated repeatedly until the fitting error meets the accuracy requirements.

[0081] Step 4: Calculate the comprehensive evaluation index δ. The larger the comprehensive evaluation index δ, the better the CO2 adsorption effect. The specific calculation formula is as follows:

[0082] δ=θ1×S+θ2×V+θ3×P+θ4×T+θ5×d+α

[0083] In the formula: S is the specific surface area, in m². 2 / kg; V is the pore volume, in cm³. 3 / kg; P is pressure, in kPa; T is temperature, in °C; d is average pore size, in nm; α is a correction factor used to adjust the accuracy of the model.

[0084] The formula for calculating the correction factor α is as follows:

[0085] α = β × (specific surface area / pore volume) × average pore diameter

[0086] In the formula: β is a constant used to adjust the magnitude of the correction factor to ensure the accuracy of the model.

[0087] The porous carbon material prepared from coal gasification slag used in the examples is a finished porous carbon material prepared through a specific process, possessing excellent pore structure and adsorption properties. The following statistical results of nine groups of porous carbon material samples further illustrate this invention.

[0088] Sample 1: Grind, dry, and sieve Sample 1 to a particle size of less than 3 mm. Select a general-purpose SSA-4000 analyzer and check that all components are functioning properly, ensuring the gas adsorption system, temperature control system, and pressure measurement system are all in good working order. Accurately weigh 150 mg of the prepared sample and place it into a sample tube. Place the sample tube containing the sample into the degassing station. Then, place a heating sleeve on the sample tube and set the degassing temperature to 200℃. Turn on the vacuum pump and begin heating and vacuum degassing the sample for 10 hours to fully remove the impurity gases adsorbed on the material surface. After degassing, remove the sample tube from the degassing station and quickly place it in liquid nitrogen to cool to liquid nitrogen temperature. At liquid nitrogen temperature, introduce nitrogen into the sample tube through an automatic control device and measure the amount of nitrogen adsorbed in the sample to obtain the adsorption isotherm of Sample 1. Based on the adsorption isotherm of Sample 1, the specific surface area of ​​Sample 1 is calculated to be 1296 m². 2 / kg, pore volume is 0.92cm³ 3 / kg, with an average pore size of 19.23nm. Two pretreated samples of sample 1 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption apparatus under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 1 under different pressures and temperatures was obtained. The comparison graph of CO2 adsorption capacity of sample 1 at 25℃ and under different pressure conditions is shown in the figure. Figure 2 As shown.

[0089] Sample 2: The pretreatment process and adsorption isotherm acquisition process of Sample 1 were the same. Based on the adsorption isotherm of Sample 2, the specific surface area of ​​Sample 2 was calculated to be 10¹⁸ m². 2 / kg, pore volume is 0.823cm³ 3 / kg, with an average pore size of 29.57nm. Two pretreated samples 2 were placed at 25℃ and 50℃ respectively, and CO2 was continuously introduced into the sample using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa to conduct adsorption experiments, and the CO2 adsorption capacity of sample 2 under different pressures and temperatures was obtained.

[0090] Sample 3: Following the same pretreatment process and adsorption isotherm acquisition process as Sample 1, the specific surface area of ​​Sample 3 was calculated to be 1107 m². 2 / kg, pore volume is 0.821cm³ 3 / kg, with an average pore size of 20.61nm. Two pretreated samples 3 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 3 under different pressures and temperatures was obtained.

[0091] Sample 4: Following the same pretreatment process and adsorption isotherm acquisition process as Sample 1, the specific surface area of ​​Sample 4 was calculated to be 852 m². 2 / kg, pore volume is 0.871cm³ 3 / kg, with an average pore size of 6.131nm. Two pretreated samples 4 were placed at 25℃ and 50℃ respectively, and CO2 was continuously introduced into the samples using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa to conduct adsorption experiments, and the CO2 adsorption capacity of sample 4 under different pressures and temperatures was obtained.

[0092] Sample 5: The pretreatment process and adsorption isotherm acquisition process of Sample 1 were the same. Based on the adsorption isotherm of Sample 5, the specific surface area of ​​Sample 5 was calculated to be 925 m². 2 / kg, pore volume is 0.675cm³ 3 / kg, with an average pore size of 3.796nm. Two pretreated samples 5 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 5 under different pressures and temperatures was obtained.

[0093] Sample 6: The pretreatment process and adsorption isotherm acquisition process of Sample 1 were the same. Based on the adsorption isotherm of Sample 6, the specific surface area of ​​Sample 6 was calculated to be 10¹⁷ m². 2 / kg, pore volume is 0.816cm³ 3 / kg, with an average pore size of 4.469nm. Two pretreated samples 6 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 6 under different pressures and temperatures was obtained.

[0094] Sample 7: Following the same pretreatment process and adsorption isotherm acquisition process as Sample 1, the specific surface area of ​​Sample 7 was calculated to be 156 m². 2 / kg, pore volume is 0.194cm³ 3 / kg, with an average pore size of 50.1nm. Two pretreated samples 7 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 7 under different pressures and temperatures was obtained.

[0095] Sample 8: The pretreatment process and adsorption isotherm acquisition process of Sample 1 were the same. Based on the adsorption isotherm of Sample 8, the specific surface area of ​​Sample 8 was calculated to be 144 m². 2 / kg, pore volume is 0.186cm³ 3 / kg, with an average pore size of 19.17nm. Two pretreated samples 8 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 8 under different pressures and temperatures was obtained.

[0096] Sample 9: The pretreatment process and adsorption isotherm acquisition process of Sample 1 were the same. Based on the adsorption isotherm of Sample 9, the specific surface area of ​​Sample 9 was calculated to be 119 m². 2 / kg, pore volume is 0.176cm³ 3 / kg, with an average pore size of 94.43nm. Two pretreated samples 9 were placed at 25℃ and 50℃ respectively, and adsorption experiments were conducted using a physical adsorption instrument under pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa and 50kPa by continuously introducing CO2. The CO2 adsorption capacity of sample 9 under different pressures and temperatures was obtained.

[0097] The specific surface area, pore volume, and average pore diameter data of samples 1 to 9 are summarized in Table 1 below.

[0098] Table 1. Specific surface area, pore volume, and average pore diameter data for samples 1 to 9.

[0099] <![CDATA[Specific surface area (m 2 / kg)]]> <![CDATA[Pore volume (cm 3 / kg)]]> Average pore size (nm) Sample 1 1295 0.92 19.23 Sample 2 1018 0.823 29.57 Sample 3 1107 0.821 20.61 Sample 4 852 0.871 6.131 Sample 5 925 0.675 3.796 Sample 6 1017 0.816 4.469 Sample 7 156 0.194 50.1 Sample 8 144 0.186 19.17 Sample 9 119 0.176 94.43

[0100] The CO2 adsorption results of samples 1 to 9 under a pressure of 100 kPa and at different temperatures are summarized in Table 2 below. A comparison of CO2 adsorption capacity of samples 1 to 9 under a temperature of 25℃ and a pressure of 100 kPa is shown in the figure below. Figure 3 As shown.

[0101] Table 2 shows the CO2 adsorption results of samples 1 to 9 under a pressure of 100 kPa and at different temperatures.

[0102] Temperature (°C) Pressure (kPa) <![CDATA[CO2 adsorption capacity (mol / kg)]]> Sample 1 25 100 2.65 Sample 2 25 100 2.08 Sample 3 25 100 2.54 Sample 4 25 100 1.98 Sample 5 25 100 2.14 Sample 6 25 100 2.28 Sample 7 25 100 0.68 Sample 8 25 100 0.62 Sample 9 25 100 0.47 Sample 1 50 100 1.01 Sample 2 50 100 0.59 Sample 3 50 100 0.95 Sample 4 50 100 0.61 Sample 5 50 100 0.58 Sample 6 50 100 0.69 Sample 7 50 100 0.12 Sample 8 50 100 0.11 Sample 9 50 100 0.09

[0103] The CO2 adsorption results of samples 1 to 9 under different temperature and pressure conditions at 25℃ are summarized in Table 3 below.

[0104] Table 3 shows the CO2 adsorption results of samples 1 to 9 at 25℃ and under different pressure conditions.

[0105]

[0106]

[0107] As shown in Tables 1, 2, and 3, the porous carbon materials prepared from coal gasification slag through different processes exhibit different physical properties and varying CO2 adsorption effects. Specifically, a larger specific surface area, larger pore volume, and smaller average pore size result in more adsorption sites and better adsorption performance. Adsorption data at different pressures and temperatures reveal that pressure and temperature significantly influence adsorption performance. As pressure increases, the CO2 adsorption capacity of the porous carbon materials typically increases, while as temperature increases, the CO2 adsorption capacity typically decreases. This is because the adsorption process is largely exothermic, and high temperatures are unfavorable for adsorption.

[0108] After combining and normalizing the data from Tables 1, 2, and 3, a binary regression was performed to obtain the weighting ratios (θ1, θ2, θ3, θ4, θ5) of the specific surface area, pore volume, average pore size, pressure, and temperature of the porous carbon material for CO2 adsorption. The radar chart showing these weighting ratios is shown below. Figure 5 As shown, the comprehensive evaluation index δ was calculated, and the comprehensive evaluation indices δ for samples 1 to 5 under 100 kPa and 25℃ and 100 kPa and 50℃ conditions are shown in Table 4 below. A comparison graph of the comprehensive evaluation index δ for samples 1 to 5 under 100 kPa pressure and different temperature conditions is shown below. Figure 4 As shown.

[0109] Table 4 shows the comprehensive evaluation index δ of samples 1 to 5 under conditions of 100 kPa and 25℃ and 100 kPa and 50℃.

[0110]

[0111] As shown in Table 4, Sample 1 exhibits the highest comprehensive evaluation index δ at 100 kPa and 25℃, indicating the best CO2 adsorption effect. In other words, when preparing porous carbon materials from coal gasification slag, the porous carbon material prepared using the process described for Sample 1 demonstrates the best CO2 adsorption effect at 100 kPa and 25℃.

[0112] This method for evaluating the CO2 capture performance of porous carbon materials can comprehensively and effectively assess the CO2 adsorption performance of porous carbon materials, thereby accurately measuring the CO2 capture effect of porous carbon materials. It can provide a theoretical basis and data support for optimizing the preparation process of porous carbon materials and improving their adsorption efficiency.

Claims

1. A method for evaluating the performance of porous carbon materials in capturing CO2, characterized in that, Specifically, the following steps are included: Step 1: Obtain the specific surface area, pore volume, and average pore diameter of the porous carbon material. Step 2: Conduct CO2 adsorption experiments under different pressure and temperature conditions, and record the pressure, temperature and CO2 adsorption amount when the porous carbon material captures CO2. Step 3: Based on the data from Step 1 and Step 2, perform multivariate regression using the dichotomy method and fit the regression curve to determine the weight ratios θ1, θ2, θ3, θ4, and θ5 of the specific surface area, pore volume, average pore size, pressure, and temperature of the porous carbon material on the CO2 adsorption effect. Step 4: Calculate the comprehensive evaluation index δ. The larger the comprehensive evaluation index δ, the better the CO2 adsorption effect. The specific calculation formula is as follows: δ=θ1×S+θ2×V+θ3×P+θ4×T+θ5×d+α In the formula: S is the specific surface area, in m². 2 / kg; V is the pore volume, in cm³. 3 / kg; P is pressure, in kPa; T is temperature, in °C; d is average pore size, in nm; α is correction factor.

2. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, The formula for calculating the correction factor α in Step 4 is as follows: α = β × (specific surface area / pore volume) × average pore diameter In the formula: β is a constant.

3. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, In Step 3, when performing multiple regression using the bisection method and fitting the regression curve, the regression curve is fitted and the fitting error is calculated. If the fitting error meets the preset accuracy requirements, the curve is determined to be the best-fit curve; otherwise, the fitting parameters are adjusted, and the regression curve is fitted and the fitting error is calculated repeatedly until the fitting error meets the accuracy requirements.

4. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, In Step 1, the specific surface area and pore volume were determined by nitrogen adsorption-desorption isotherms. The specific surface area was calculated using the BET method, and the pore volume and average pore diameter were calculated using the BJH method.

5. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 4, characterized in that, When calculating specific surface area using the BET method, the BET formula is as follows: In the formula: V is the amount of nitrogen adsorbed, V m P is the monolayer adsorption capacity, P is the partial pressure of nitrogen, P0 is the saturated vapor pressure of nitrogen, and C is the BET constant. Based on the adsorption isotherm data, select an appropriate relative pressure range and calculate the pressure for each data point. and Then, a linear fit was performed, and the monolayer adsorption capacity V was calculated by using the slope and intercept of the fitted line. m and the BET constant C; The formula for calculating specific surface area is as follows: In the formula: S is the specific surface area, N is Avogadro's constant, σ is the cross-sectional area of ​​nitrogen molecules, and m is the mass of the sample.

6. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 4, characterized in that, When calculating pore volume and average pore size using the BJH method, data points from adsorption or desorption isotherms are selected and arranged in order of decreasing pressure. The pore size D corresponding to each data point is then calculated using the Kelvin equation. In the formula: γ is the surface tension of nitrogen, θ is the contact angle, R is the gas constant, ρ is the density of nitrogen, P is the partial pressure of nitrogen, and P0 is the saturated vapor pressure of nitrogen. The average aperture d is calculated using the following formula: In the formula: n is the number of apertures; Calculate the pore volume increment ΔV for each pore diameter: ΔV=V ads (P i )-V ads (P i+1 ) In the formula: V ads (P i ) and V ads (P i+1 ) represent the adsorption amounts of the i-th and i+1-th data points, respectively; Calculate the sum of the pore volume increments V corresponding to all pore diameters. total : In total = ∑ΔV.

7. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, In Step 2, the selection of different pressure and temperature conditions is based on the trend of the adsorption performance of porous carbon materials under different pressure and temperature conditions. The specific pressure and temperature conditions are selected according to the experimental requirements and the characteristics of porous carbon materials.

8. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, For porous carbon materials prepared by different preparation processes, the optimal preparation process for porous carbon materials is selected based on the calculation results of the comprehensive evaluation index δ.

9. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, For the adsorption operation environment of porous carbon materials under different pressures and temperatures, the optimal pressure and temperature operation environment is selected based on the calculation results of the comprehensive evaluation index δ to be applied to the adsorption of CO2 by porous carbon materials.

10. The method for evaluating the performance of porous carbon materials in capturing CO2 according to claim 1, characterized in that, Porous carbon materials are prepared from coal gasification slag.

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