Performance evaluation method for capturing CO2 by porous carbon material

Abstract

The invention discloses a method for evaluating the CO2 trapping performance of a porous carbon material. The method comprises the following steps: acquiring the specific surface area, pore volume and average pore size of the porous carbon material; cO2 adsorption experiments are carried out under different pressure intensity and temperature conditions, and the pressure intensity, the temperature and the CO2 adsorption capacity when the porous carbon material captures CO2 are recorded; performing multiple regression by using a dichotomy, fitting a regression curve, and determining the weight ratios theta1, theta2, theta3, theta4 and theta5 of the specific surface area, the pore volume, the average pore size, the pressure intensity and the temperature of the porous carbon material to the CO2 adsorption effect; and calculating a comprehensive evaluation index delta. The method for evaluating the performance of the porous carbon material for capturing CO2 can comprehensively and effectively evaluate the adsorption performance of the porous carbon material on CO2, so that the capturing effect of the porous carbon material on CO2 is accurately measured, and a theoretical basis and data support can be provided for optimizing the preparation process of the porous carbon material and improving the adsorption efficiency of the porous carbon material.

Description

Technical Field

[0001] The present invention relates to a material performance evaluation method, in particular to a method for capturing CO2 using porous carbon materials. 2 Performance evaluation method for CO 2 Capture technology field. Background Art

[0002] With the rapid development of modern industry, CO 2 The increasing emissions have caused serious impacts on the environment, such as global warming, rising sea levels, and ecosystem destruction. Therefore, it is necessary to develop efficient CO 2 Capture materials have become an important research direction. At present, the adsorption method is used to capture CO 2 The research focus of the technology is on adsorbents and adsorption processes, among which adsorbents are the top priority. 2 The adsorbent should have high adsorption capacity, fast adsorption rate and good CO 2 The porous carbon material, that is, the carbon-based material with high specific surface area and rich pore structure, has high porosity and surface area and suitable pore size, which can be used for CO 2 Providing a large number of adsorption sites and fast diffusion channels, thus ensuring efficient adsorption capacity and selectivity, this feature makes porous carbon materials very suitable for CO 2 The capture and storage field has broad application prospects, especially in power plants, refineries, etc. where large amounts of CO are generated. 2 Coal gasification slag is an industrial waste with rich carbonaceous components and complex chemical structure. After being treated by a specific process, coal gasification slag can be converted into porous carbon materials with high specific surface area and porous properties.

[0003] In order to evaluate the porous carbon materials against CO 2 The adsorption performance of a material usually requires a professional evaluation method. Common evaluation indicators include specific surface area, pore volume, pore size distribution, pore morphology, etc. Specific surface area is the total surface area per unit mass of a substance. A material with a larger specific surface area can provide more reaction sites and adsorption sites, and its surface effects such as surface activity, surface adsorption capacity and catalytic ability are more significant. Pore volume is the total volume of pores per unit mass or volume of a material. In applications such as catalysis, drug delivery, energy storage and conversion, pore volume is directly related to the storage capacity of the material and the efficiency of material transfer. Pore size distribution refers to the change 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 inside or on the surface of a material, which also has an important influence on the adsorption, filtration, storage, catalysis and other properties of porous carbon materials.

[0004] However, the existing technology for porous carbon materials to react with CO 2 The evaluation methods of the adsorption performance of porous carbon materials mainly focus on a single indicator, such as only considering the specific surface area or pore volume, and there is no comprehensive and effective evaluation method to evaluate and optimize the adsorption performance of porous carbon materials on CO under different pressure and temperature conditions. 2 Adsorption performance: Researchers and developers have been unable to accurately measure the CO adsorption performance of porous carbon materials. 2 The capture effect of porous carbon materials and the inability to determine whether the performance of porous carbon materials meets expectations are urgent issues to be solved in the industry. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a porous carbon material for capturing CO 2 The performance evaluation method can comprehensively and effectively evaluate the performance of porous carbon materials in CO 2 The adsorption performance of porous carbon materials can be accurately measured. 2 The capture effect can provide a theoretical basis and data support for optimizing the preparation process of porous carbon materials and improving the adsorption efficiency of porous carbon materials.

[0006] To achieve the above purpose, the porous carbon material captures CO 2 The performance evaluation method 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: CO 2 Adsorption experiments, recording CO capture by porous carbon materials 2 The pressure, temperature and CO 2 Adsorption capacity;

[0009] Step 3, based on the data of Step 1 and Step 2, use the dichotomy method to perform multiple regression and fit the regression curve to determine the specific surface area, pore volume, average pore size, pressure, and temperature of the porous carbon material for CO 2 Weight ratio of adsorption effect θ 1 ,θ 2 ,θ 3 ,θ 4 ,θ 5 ;

[0010] Step 4, calculate the comprehensive evaluation index δ. If the comprehensive evaluation index δ is the largest, then CO 2 The better the adsorption effect, the specific calculation formula is as follows:

[0011] δ=θ 1 ×S+θ 2 ×V+θ3 ×P+θ 4 ×T+θ 5 ×d+α

[0012] Where: S is the specific surface area, unit: m 2 / kg; V is the pore volume, unit is cm 3 / kg; P is pressure, unit is kPa; T is temperature, unit is ℃; d is average pore size, unit is nm; α is correction factor.

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

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

[0015] Where: β is a constant.

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

[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 by the BET method, and the pore volume and average pore size are calculated by the BJH method.

[0018] Furthermore, when the BET method is used to calculate the specific surface area, the BET formula is as follows:

[0019]

[0020] Where: V is the adsorption amount of nitrogen, V m is the monolayer adsorption capacity, P is the partial pressure of nitrogen, P 0 is the saturated vapor pressure of nitrogen, C is the BET constant;

[0021] According to the adsorption isotherm data, select the appropriate relative pressure range and calculate the and Then a linear fit is performed, and the monolayer adsorption capacity V is calculated by the slope and intercept of the fitting line. m and BET constant C;

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

[0023]

[0024] Where: S is the specific surface area, N is the Avogadro constant, σ is the cross-sectional area of ​​the nitrogen molecule, and m is the mass of the sample.

[0025] Furthermore, when the BJH method is used to calculate the pore volume and average pore diameter, the data points of the adsorption isotherm or desorption isotherm are selected and arranged in order of decreasing pressure, and the pore diameter D corresponding to each data point is calculated according to the Kelvin equation:

[0026]

[0027] Where: 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, P 0 is the saturated vapor pressure of nitrogen;

[0028] The average pore diameter d is calculated by the following formula:

[0029]

[0030] Where: n is the number of apertures;

[0031] Calculate the pore volume increment ΔV corresponding to each pore size:

[0032] ΔV=V ads (P i )-V ads (P i+1 )

[0033] Where: V ads (P i ) and V ads (P i+1 ) are the adsorption amounts of the i-th and i+1-th data points respectively;

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

[0035] V total =∑ΔV.

[0036] Furthermore, in Step 2, the selection of different pressure and temperature conditions is based on the change 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.

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

[0038] Furthermore, for the porous carbon material adsorption operating environment with different pressures and temperatures, the optimal pressure and temperature operating environment is selected through the calculation results of the comprehensive evaluation index δ to be applied to the porous carbon material adsorption of CO 2 .

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

[0040] Compared with the existing technology, the porous carbon material can capture CO 2 The performance evaluation method has the following beneficial effects:

[0041] 1. This porous carbon material captures CO 2 The performance evaluation method comprehensively considers the five key factors of the specific surface area, pore volume, average pore size, pressure and temperature of porous carbon materials, and establishes a more comprehensive comprehensive evaluation system, which can more accurately reflect the adsorption performance of porous carbon materials under different conditions.

[0042] 2. The porous carbon material prepared from coal gasification slag has unique physical and chemical properties. The evaluation methods for porous carbon materials in the prior art cannot be fully applied to the porous carbon material. The porous carbon material captures CO 2 The performance evaluation method of the porous carbon material prepared from coal gasification slag fully considers the characteristics of the porous carbon material prepared from coal gasification slag, and can more accurately evaluate its adsorption performance. It can provide a theoretical basis and data support for the efficient utilization of coal gasification slag, which can not only reduce the landfill volume of coal gasification slag and reduce environmental pollution, but also promote the utilization of environmentally friendly materials in CO 2 Its application in the capture field has considerable environmental benefits.

[0043] 3. This porous carbon material captures CO 2 The performance evaluation method can provide a scientific basis for the production decision 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 capture of CO by porous carbon materials in coal gasification slag. 2 The industrialization process of technology will promote the development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flow chart of the present invention;

[0045] Figure 2 The CO of sample 1 of the embodiment of the present invention at 25°C temperature and different pressure conditions is 2 Comparison chart of adsorption amount;

[0046] Figure 3 The CO of samples 1 to 9 of the present invention at 25°C and 100 kPa 2 Comparison chart of adsorption amount;

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

[0048] Figure 5 It is a radar chart of the weighted ratios of specific surface area, pore volume, average pore diameter, temperature and pressure of the embodiments of the present invention. DETAILED DESCRIPTION

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

[0050] like Figure 1 As shown, the porous carbon material captures CO 2 The performance evaluation method of the porous carbon material is to first obtain the specific surface area, pore volume and average pore size of the porous carbon material; then combine the CO 2 The adsorption experiment collects the adsorption data; then the dichotomy method is used to find the best fitting curve, which can reflect the influence of pressure and temperature on the adsorption performance, so as to determine the weight ratio under different pressures and temperatures. Finally, these weights are used to calculate the comprehensive evaluation index δ, and then evaluate the CO absorption performance of porous carbon materials under actual working conditions. 2 Adsorption capacity. 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 are measured by nitrogen adsorption-desorption isotherms, the specific surface area is calculated by the BET method, and the pore volume and average pore diameter are calculated by the BJH method.

[0052] The specific surface area of ​​porous carbon materials is calculated using the BET method: The BET method is based on the multi-molecular layer adsorption theory and calculates the specific surface area of ​​the sample by measuring the amount of nitrogen adsorbed on the sample surface. The details are as follows:

[0053] a. Pre-treat the porous carbon material sample at 200°C and vacuum degree 10 -3 ~10 -5 The samples were treated at 400 °C for 10 h to remove impurities adsorbed on the sample surface (such as water molecules and other volatile substances).

[0054] b. Select nitrogen (N 2 ) is used as the adsorbate gas, which is chemically inert, readily available and has suitable adsorption characteristics at liquid nitrogen temperature (77K).

[0055] c. Place the pretreated sample into the adsorption instrument and gradually increase the relative pressure of the adsorbate gas (P / P 0 , P is the actual adsorption pressure, P 0is the saturated vapor pressure of the adsorbate at that temperature), and the adsorption amount (V) of the adsorbate on the sample surface at different relative pressures is measured by the gravimetric method (measuring the weight change of the sample adsorbate).

[0056] d. Calculated by BET equation:

[0057]

[0058] Where: V is the adsorption amount of nitrogen, V m is the monolayer adsorption capacity, P is the partial pressure of nitrogen, P 0 is the saturated vapor pressure of nitrogen, and C is the BET constant.

[0059] According to the adsorption isotherm data, select an appropriate relative pressure range (usually 0.05-0.35) and calculate the relative pressure of each data point. and Then a linear fit is performed, and the monolayer adsorption capacity V is calculated by the slope and intercept of the fitting line. m and BET constant C.

[0060] e. Calculation of specific surface area:

[0061]

[0062] Where: S is the specific surface area, N is the Avogadro constant, σ is the cross-sectional area of ​​the nitrogen molecule (take 0.162nm 2 ), m is the mass of the sample.

[0063] The BJH method is used to calculate the pore volume and average pore size of porous carbon materials: The BJH method is based on the Kelvin equation and calculates the pore size distribution and pore volume of porous carbon materials through nitrogen adsorption-desorption isotherm data. The BJH method assumes that the pores are rigid and have a regular shape (such as a cylinder), and selects the data points of the adsorption isotherm or desorption isotherm and arranges them in order of decreasing pressure. The details are as follows:

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

[0065] b. Place the pretreated sample in the adsorption instrument and conduct an adsorption experiment at a constant temperature of 77K, gradually increasing the relative pressure of the adsorbate gas (P / P 0 , P is the actual adsorption pressure, P 0 is the saturated vapor pressure of the adsorbate at that temperature), and record the adsorption amount of the sample at different pressures, and record the adsorption isotherm data, including the relative pressure P / P 0 and the corresponding adsorption amount V.

[0066] c. Relative pressure P / P 0 The adsorption isotherm is drawn with V as the horizontal axis and the adsorption amount V as the vertical axis.

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

[0068]

[0069] Where: 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, P 0 is the saturated vapor pressure of nitrogen.

[0070] The average pore diameter d is calculated by the following formula:

[0071]

[0072] Where: n is the number of apertures.

[0073] Calculate the pore volume increment ΔV corresponding to each pore size:

[0074] ΔV=V ads (P i )-V ads (P i+1 )

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

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

[0077] V total =∑ΔV.

[0078] Step 2: CO 2 Adsorption experiments, recording CO capture by porous carbon materials 2 The pressure, temperature and CO 2 Adsorption amount. The selection of different pressure and temperature conditions is based on the change 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.

[0079] Step 3, according to the adsorption data of the adsorption experiment, use the dichotomy method to perform multiple regression and find the best fitting curve to determine the specific surface area, pore volume, average pore size, pressure, and temperature of the porous carbon material for CO 2 Weight ratio of adsorption effect θ 1 ,θ 2 ,θ 3 ,θ 4 ,θ 5 .

[0080] When searching for the best fitting curve, fit the regression curve and calculate the fitting error. If the fitting error meets the preset accuracy requirements, the curve is determined to be the best fitting curve; otherwise, adjust the fitting parameters, repeatedly fit the regression curve and calculate the fitting error until the fitting error meets the accuracy requirements.

[0081] Step 4, calculate the comprehensive evaluation index δ. If the comprehensive evaluation index δ is the largest, then CO 2 The better the adsorption effect, the specific calculation formula is as follows:

[0082] δ=θ 1 ×S+θ 2 ×V+θ 3 ×P+θ 4 ×T+θ 5 ×d+α

[0083] Where: S is the specific surface area, unit: m 2 / kg; V is the pore volume, unit is cm 3 / kg; P is pressure, unit is kPa; T is temperature, unit is ℃; d is the average pore size, unit is nm; α is the correction factor, which is used to adjust the accuracy of the model.

[0084] The calculation formula of the correction factor α is as follows:

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

[0086] Where: β is a constant, which is used to adjust the amplitude of the correction factor to ensure the accuracy of the model.

[0087] The porous carbon material prepared from coal gasification slag used in the embodiment is a finished porous carbon material prepared by a specific process, and has good pore structure and adsorption properties. The present invention is further described below through the statistical results of 9 groups of porous carbon material samples.

[0088] Sample 1: Grind, dry and sieve sample 1 to a particle size of less than 3 mm. Select a general-purpose SSA-4000 tester, check whether all components of the instrument are normal, and ensure that the gas adsorption system, temperature control system and pressure measurement system are in good working condition. Accurately weigh 150 mg of the prepared sample and put it into the sample tube, and install the sample tube containing the sample into the degassing station. Then put the heating pack on the sample tube and set the degassing temperature to 200°C. Turn on the vacuum pump and start heating and vacuum degassing the sample for 10 hours to fully remove the impurity gas adsorbed on the surface of the material. After degassing is completed, take the sample tube out of the degassing station and quickly put it into liquid nitrogen to cool to liquid nitrogen temperature. At liquid nitrogen temperature, nitrogen is introduced into the sample tube through an automatic control device, and the nitrogen adsorption amount of the sample is measured to obtain the adsorption isotherm of sample 1. According to the adsorption isotherm of sample 1, the specific surface area of ​​sample 1 is calculated to be 1296m 2 / kg, pore volume is 0.92cm 3 / kg, the average pore size is 19.23nm. Take two pre-treated samples 1 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 1 at different pressures and temperatures. 2 Adsorption amount. CO adsorption of sample 1 at 25°C and different pressures 2 Comparison of adsorption capacity Figure 2 shown.

[0089] Sample 2: Following the same pretreatment process and adsorption isotherm acquisition process as sample 1, the specific surface area of ​​sample 2 was calculated to be 1018m based on the adsorption isotherm of sample 2. 2 / kg, pore volume is 0.823cm 3 / kg, the average pore size is 29.57nm. Take two pre-treated samples 2 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 2 at different pressures and temperatures. 2 Adsorption amount.

[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 m 2 / kg, pore volume is 0.821cm 3 / kg, the average pore size is 20.61nm. Take two pre-treated samples 3 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 3 at different pressures and temperatures. 2 Adsorption amount.

[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 m 2 / kg, pore volume is 0.871cm 3 / kg, the average pore size is 6.131nm. Take two pre-treated samples 4 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 4 at different pressures and temperatures. 2 Adsorption amount.

[0092] Sample 5: Following the same pretreatment process and adsorption isotherm acquisition process as sample 1, the specific surface area of ​​sample 5 was calculated to be 925 m 2 / kg, pore volume is 0.675cm 3 / kg, the average pore size is 3.796nm. Take two pre-treated samples 5 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 5 at different pressures and temperatures. 2 Adsorption amount.

[0093] Sample 6: Following the same pretreatment process and adsorption isotherm acquisition process as sample 1, the specific surface area of ​​sample 6 was calculated to be 1017m based on the adsorption isotherm of sample 6. 2 / kg, pore volume is 0.816cm 3 / kg, the average pore size is 4.469nm. Take two pre-treated samples 6 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 6 at different pressures and temperatures. 2 Adsorption amount.

[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 m 2 / kg, pore volume is 0.194cm 3 / kg, the average pore size is 50.1nm. Take two pre-treated samples 7 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO of sample 7 at different pressures and temperatures. 2 Adsorption amount.

[0095] Sample 8: Following the same pretreatment process and adsorption isotherm acquisition process as sample 1, the specific surface area of ​​sample 8 was calculated to be 144 m 2 / kg, pore volume is 0.186cm 3 / kg, the average pore size is 19.17nm. Take two pre-treated samples 8 and place them at 25℃ and 50℃ respectively. Use a physical adsorption instrument to continuously introduce CO at 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa pressure environments. 2 Adsorption experiments were carried out to obtain the CO content of sample 8 at different pressures and temperatures. 2 Adsorption amount.

[0096] Sample 9: Following the same pretreatment process and adsorption isotherm acquisition process as sample 1, the specific surface area of ​​sample 9 was calculated to be 119 m 2 / kg, pore volume is 0.176cm 3 / kg, the average pore size is 94.43nm. Two pre-treated samples 9 were placed at 25℃ and 50℃ respectively, and a physical adsorption instrument was used to continuously introduce CO at pressures of 100kPa, 90kPa, 80kPa, 70kPa, 60kPa, and 50kPa respectively. 2 Adsorption experiments were carried out to obtain the CO of sample 9 at different pressures and temperatures. 2 Adsorption amount.

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

[0098] Table 1 Specific surface area, pore volume and average pore size data of 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 above samples 1 to 9 were placed in a 100 kPa pressure environment and CO at different temperatures.2 The adsorption results are summarized in Table 2. CO adsorption of samples 1 to 9 at 25°C and 100 kPa 2 Comparison of adsorption capacity Figure 3 shown.

[0101] Table 2 CO2 of samples 1 to 9 at 100 kPa pressure and different temperatures 2 Adsorption results

[0102] Temperature(℃) Pressure(kPa) <![CDATA[CO 2 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 above samples 1 to 9 were placed in a 25°C temperature environment and CO 2 The adsorption results are summarized in Table 3.

[0104] Table 3 CO2 concentration of samples 1 to 9 at 25°C temperature and different pressures 2 Adsorption results

[0105]

[0106]

[0107] It can be seen from Tables 1, 2 and 3 that the physical properties of porous carbon materials prepared from coal gasification slag by different processes are different, and the adsorption of CO 2 The effect is also different. Specifically, the larger the specific surface area, the larger the pore volume, the smaller the average pore size, the more adsorption sites the material provides, and the better the adsorption performance. The adsorption data at different pressures and temperatures show that pressure and temperature also have a significant effect on adsorption performance. As the pressure increases, the porous carbon material has a stronger adsorption capacity for CO 2 The adsorption of CO by porous carbon materials usually increases with increasing temperature. 2 The adsorption amount usually decreases because the adsorption process is mostly an exothermic process and high temperature is not conducive to adsorption.

[0108] The data in Tables 1, 2, and 3 were combined and normalized, and the dichotomy method was used for multiple regression to obtain the specific surface area, pore volume, average pore size, pressure, and temperature of porous carbon materials for CO 2 Weight ratio of adsorption effect θ 1 ,θ 2 ,θ 3 ,θ 4 ,θ 5 , the weighted radar chart of specific surface area, pore volume, average pore diameter, temperature and pressure is as follows: Figure 5As shown, the comprehensive evaluation index δ is calculated, and the comprehensive evaluation index δ of samples 1 to 5 under 100 kPa, 25 ° C environment and 100 kPa, 50 ° C environment is shown in Table 4. The comparison chart of the comprehensive evaluation index δ of samples 1 to 5 under 100 kPa pressure conditions and different temperature conditions is shown in Table 4. Figure 4 shown.

[0109] Table 4 Comprehensive evaluation index δ of samples 1 to 5 under 100 kPa, 25 °C environment and 100 kPa, 50 °C environment

[0110]

[0111] It can be seen from Table 4 that the comprehensive evaluation index δ of sample 1 is the largest under the environment of 100 kPa and 25 °C. 2 That is to say, when the porous carbon material is prepared from coal gasification slag, the porous carbon material prepared by the preparation process of sample 1 is subjected to CO adsorption at 100 kPa and 25 °C. 2 The adsorption effect is the best.

[0112] Porous carbon material captures CO 2 The performance evaluation method can comprehensively and effectively evaluate the performance of porous carbon materials in CO 2 The adsorption performance of porous carbon materials can be accurately measured. 2 The capture effect can provide a theoretical basis and data support for optimizing the preparation process of porous carbon materials and improving the adsorption efficiency of porous carbon materials.

Claims

1. A method for evaluating the performance of porous carbon materials in capturing CO2, characterized in that: The specific steps include: 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 of Step 1 and Step 2, use the dichotomy method to perform multiple regression and fit the regression curve to determine the weight 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 the CO2 adsorption effect; Step 4, calculate the comprehensive evaluation index δ. The larger the comprehensive evaluation index δ is, the better the CO2 adsorption effect is. The specific calculation formula is as follows: δ=θ1×S+θ2×V+θ3×P+θ4×T+θ5×d+α Where: S is the specific surface area, unit: m 2 / kg; V is the pore volume, unit is cm 3 / kg; P is pressure, unit is kPa; T is temperature, unit is ℃; d is average pore size, unit is 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 calculation formula of the correction factor α in Step 4 is as follows: α=β×(specific surface area / pore volume)×average pore diameter Where: 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 the binary method is used for multiple regression and the regression curve is fitted, the regression curve is fitted and the fitting error is calculated. If the fitting error meets the preset accuracy requirement, the curve is determined to be the best fitting curve; otherwise, the fitting parameters are adjusted, and the regression curve is repeatedly fitted and the fitting error is calculated until the fitting error meets the accuracy requirement.

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 by the BET method, and the pore volume and average pore size were calculated by 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 the BET method is used to calculate the specific surface area, the BET formula is as follows: Where: V is the adsorption amount of nitrogen, V m 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; According to the adsorption isotherm data, select the appropriate relative pressure range and calculate the and Then a linear fit is performed, and the monolayer adsorption capacity V is calculated by the slope and intercept of the fitting line. m and BET constant C; The specific surface area calculation formula is as follows: Where: S is the specific surface area, N is the Avogadro constant, σ is the cross-sectional area of ​​the nitrogen molecule, 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 the BJH method is used to calculate the pore volume and average pore diameter, the data points of the adsorption isotherm or desorption isotherm are selected and arranged in order of decreasing pressure. The pore diameter D corresponding to each data point is calculated according to the Kelvin equation: Where: 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 pore diameter d is calculated by the following formula: Where: n is the number of apertures; Calculate the pore volume increment ΔV corresponding to each pore diameter: ΔV=V ads (P i )-V ads (P i+1 ) Where: V ads (P i ) and V ads (P i+1 ) are the adsorption amounts of the i-th and i+1-th data points respectively; Calculate the sum of the pore volume increments corresponding to all pore diameters V 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 change 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.

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 of the porous carbon materials is selected through 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: According to the porous carbon material adsorption operating environment with different pressures and temperatures, the optimal pressure and temperature operating environment is selected through the calculation results of the comprehensive evaluation index δ to be applied to the porous carbon material adsorption of CO2.

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

Images