Gravimetric isothermal adsorption device and method

Abstract

The invention relates to the technical field of petroleum geology testing equipment, in particular to a gravimetric method isothermal adsorption device and method.The gravimetric method isothermal adsorption device comprises a constant-temperature box, a plurality of weighing balances, a distribution pipe, a gas injection module, a plurality of sample containing modules, a gas exhaust module and a control module, and the gas injection module comprises a gas source, a booster pump and an air compressor; the air source is communicated with the booster pump through a pipeline, the air compressor is communicated with the booster pump through a pipeline, and a first valve is arranged on the pipeline between the air compressor and the booster pump; the booster pump is communicated with the distribution pipe through a pipeline, and a second valve is arranged on the pipeline between the booster pump and the distribution pipe; according to the invention, the plurality of sample placement modules correspond to different target pressure points respectively, so that multi-pressure-point testing is completed at one time, and accumulative errors caused by progressive pressure injection are avoided.

Description

Technical Field

[0001] This invention relates to the field of petroleum geological testing equipment technology, and in particular to a gravimetric isothermal adsorption device and method. Background Technology

[0002] Currently, the measurement of gas isothermal adsorption and desorption curves falls into two main categories: volumetric methods and gravimetric methods. The volumetric method calculates the adsorption amount based on Boyle's law and the law of conservation of mass, while the gravimetric method calculates the adsorption amount based on the weight change of the sample before and after adsorption.

[0003] Chinese patent CN106644819A, "A Large-Scale Shale Isothermal Adsorption and Desorption Device," requires increasing the sample weight to improve measurement accuracy, thereby increasing the total adsorbed gas volume and reducing experimental errors. Chinese patent CN202502025U, "High-Pressure Isothermal Adsorption Experimental Device for Coal," mainly consists of a relatively independent electronic balance and a vacuum dryer, as well as an isothermal adsorption equilibrium system and a data acquisition system that are interconnected by signal.

[0004] Both of the above patents employ a method of injecting adsorption target pressure from low to high, and then calculating the adsorption isotherm. As the adsorption target pressure increases, the cumulative error also increases, resulting in a large deviation between the obtained isothermal adsorption curve and the actual isothermal adsorption curve. Summary of the Invention

[0005] The purpose of this invention is to provide a gravimetric isothermal adsorption device and method, which solves the problem that existing gravimetric isothermal adsorption devices inject adsorption target pressure from low to high and calculate adsorption isotherms. As the adsorption target pressure increases, the accumulated error also increases, resulting in a large deviation between the obtained isothermal adsorption curve and the actual isothermal adsorption curve.

[0006] To achieve the above objectives, the present invention provides a gravimetric isothermal adsorption device and method, comprising a constant temperature chamber, multiple weighing balances, a distribution tube, a gas injection module, multiple sample placement modules, a gas extraction module, and a control module. The multiple weighing balances are disposed inside the constant temperature chamber, the multiple sample placement modules are disposed on the multiple weighing balances, the distribution tube is respectively connected to the multiple sample placement modules, the gas injection module is used to deliver gas to the distribution tube, the gas extraction module is used to extract gas from the distribution tube, and the control module is connected to the gas extraction module, the sample placement modules, and the gas injection module.

[0007] The air injection module includes an air source, a booster pump, and an air compressor. The air source and the booster pump are connected by a pipeline, and the air compressor and the booster pump are connected by a pipeline. A first valve is installed on the pipeline between the air compressor and the booster pump. The booster pump is connected to the distribution pipe by a pipeline, and a second valve is installed on the pipeline between the booster pump and the distribution pipe.

[0008] The sample placement module includes a reference container, a sample container, a third valve, and a temperature and pressure sensor. The sample container is connected to the weighing balance. The two sides of the reference container are respectively connected to the distribution pipe and the sample container through pipelines. The third valve and the temperature and pressure sensor are installed on the pipeline between the reference container and the sample container.

[0009] The vacuum pump module includes a vacuum pump and a fourth valve. The vacuum pump is connected to the distribution pipe via a pipeline. The fourth valve is located on the pipeline between the vacuum pump and the distribution pipe.

[0010] The gravimetric isothermal adsorption device further includes a pressure relief pipeline and a fifth valve, wherein the pressure relief pipeline is connected to the distribution pipe; and the fifth valve is located on the pressure relief pipeline.

[0011] The control module includes a computer and multiple data lines. The computer is electrically connected to the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and multiple weighing balances via the multiple data lines.

[0012] On the other hand, the present invention also includes a gravimetric isothermal adsorption measurement method, employing the aforementioned gravimetric isothermal adsorption device, characterized by comprising the following steps:

[0013] The sample to be tested is crushed to the target particle size, weighed, and then placed into a sample container.

[0014] Place the sample container and reference container into the constant temperature chamber and connect the distribution pipe. Turn on the booster pump to fill the reference container and sample container with helium to the maximum experimental pressure. Monitor the pressure data. If the pressure is stable within 1 hour, the system is considered to be sealed.

[0015] Each sample container corresponds to a target pressure. Multiple sample containers are filled with helium at no less than 6 different target pressures. The mass, temperature and pressure data of the sample containers at each pressure point are recorded. Based on the linear relationship between the mass and density of free gas, the free space volume of each sample container is calculated using the slope.

[0016] Turn on the vacuum pump to evacuate the reference tank, sample tank and pipeline to remove the gas, and inject methane and nitrogen into each sample tank to the preset target pressure. After the adsorption is balanced, weigh the total mass of the sample tank and calculate the adsorbed gas mass based on the difference between the total mass and the free gas mass.

[0017] Summarize the adsorption data under different target pressures and plot the isothermal adsorption curves of adsorption capacity as a function of pressure.

[0018] The present invention discloses a gravimetric isothermal adsorption device and method. By employing a design where one sample vessel corresponds to one target pressure adsorption point, n sample vessels and n reference vessels can be used simultaneously to test the adsorption amount under n different target pressure conditions. The previous pressure point is independent of the next pressure point, completely eliminating cumulative errors and effectively solving the problem of error accumulation caused by the gradual increase of pressure in the prior art. Combined with a high-precision lifting balance, a high-precision temperature and pressure sensor, and a constant temperature device, the testing accuracy is further improved, and fully automatic operation is achieved, avoiding human operation errors, thereby obtaining a more accurate isothermal adsorption curve. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 This is a schematic diagram of the gravimetric isothermal adsorption device according to the first embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the sample container according to the second embodiment of the present invention.

[0022] Figure 3 This is a flowchart of the gravimetric isothermal adsorption measurement method of the present invention.

[0023] In the diagram: 101-Constant Temperature Chamber, 102-Weighing Balance, 103-Distribution Pipe, 104-Gas Injection Module, 105-Sample Placement Module, 106-Gas Extraction Module, 107-Control Module, 108-Gas Source, 109-Booster Pump, 110-Air Compressor, 111-Reference Tank, 112-Sample Tank, 113-Third Valve, 114-Temperature and Pressure Sensor, 115-Vacuum Pump, 116-Fourth Valve, 117-Pressure Relief Pipeline, 118-Fifth Valve, 119-Computer, 120-Data Cable, 121-First Pressure Gauge, 122-First Valve, 123-Second Valve, 124-Second Pressure Gauge, 201-Sample Tank Lid, 202-Tank Body, 203-Stainless Steel Pipe, 204-Piston, 205-Filter Head, 206-Stainless Steel Pipeline, 207-Sealing Ring. Detailed Implementation

[0024] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0025] First embodiment:

[0026] Please see Figure 1 ,in Figure 1 This is a schematic diagram of a gravimetric isothermal adsorption device.

[0027] This invention provides a gravimetric isothermal adsorption device, comprising a constant temperature chamber 101, multiple weighing balances 102, a distribution pipe 103, a gas injection module 104, multiple sample placement modules 105, a vacuum module 106, a control module 107, a pressure relief pipeline 117, and a fifth valve 118. The sample placement module 105 includes a reference container 111, a sample container 112, a third valve 113, and a temperature and pressure sensor 114. The vacuum module 106 includes a vacuum pump 115 and a fourth valve 116. The control module 107 includes a computer 119 and multiple data lines 120. By employing a design where one sample container 112 corresponds to one target pressure adsorption point, n sample containers 112 and n reference containers 111 can simultaneously test the adsorption amount under n different target pressure conditions. The preceding pressure point is independent of the following pressure point, eliminating cumulative errors. It is understood that the aforementioned scheme can be used to reduce testing errors and can also be used to adjust the capacity of the sample container 112 to reduce free space volume, further reducing testing errors.

[0028] In this specific embodiment, multiple weighing balances 102 are disposed inside the constant temperature chamber 101, multiple sample placement modules 105 are disposed on the multiple weighing balances 102, and the distribution pipes 103 are respectively connected to the multiple sample placement modules 105. The gas injection module 104 is used to supply gas to the distribution pipes 103, and the gas extraction module 106 is used to extract gas from the distribution pipes 103. The control module 107 is connected to the gas extraction module 106, the sample placement modules 105, and the gas injection module 104. The gas injection module 104 includes a gas source 108 and a pressurization unit. Pump 109 and air compressor 110 are provided. The air source 108 is connected to the booster pump 109 through a pipeline, and a first pressure gauge 121 is provided on the pipeline between the air source 108 and the booster pump 109. The air compressor 110 is connected to the booster pump 109 through a pipeline, and a first valve 122 is provided on the pipeline between the air compressor 110 and the booster pump 109. The booster pump 109 is connected to the distribution pipe 103 through a pipeline, and a second valve 123 and a second pressure gauge 124 are provided on the pipeline between the booster pump 109 and the distribution pipe 103.

[0029] The accuracy of the temperature and pressure sensor 114 is not less than ±0.1% FS, the temperature control accuracy of the constant temperature box 101 is not less than ±0.5 °C, and the accuracy of the weighing balance 102 is not less than ±0.001 g.

[0030] Secondly, the sample tank 112 is connected to the weighing balance 102; both sides of the reference tank 111 are respectively connected to the distribution pipe 103 and the sample tank 112 through pipelines; the third valve 113 and the temperature and pressure sensor 114 are arranged on the pipeline between the reference tank 111 and the sample tank 112.

[0031] At the same time, the air extraction module 106 includes a vacuum pump 115 and a fourth valve 116, and the vacuum pump 115 is connected to the distribution pipe 103 through a pipeline; the fourth valve 116 is arranged on the pipeline between the vacuum pump 115 and the distribution pipe 103.

[0032] Before the experiment starts, samples with a particle size of 0.25 mm to 0.18 mm are loaded into the sample tank 112, and then the sample placement module 105 composed of the sample tank 112 and the reference tank 111 is placed on the weighing balance 102 in the constant temperature box 101. The gas injection module 104 and the air extraction module 106 are connected through the distribution pipe 103; first, the airtightness is checked. Helium is filled into the reference tank 111 and the sample tank 112 by the booster pump 109 of the gas injection module 104 until the highest test pressure. The pressure is monitored by the temperature and pressure sensor 114. If the pressure is stable within 1 hour, the seal is qualified; then the free space volume is measured. The corresponding valves are opened, and helium with different pressures is filled into the system by the booster pump 109 (the number of pressure points is not less than 6). The free gas mass at each pressure point is recorded by the weighing balance 102. Combining the temperature and pressure data collected by the temperature and pressure sensor 114, the free space volume is calculated through the linear fitting slope of the free gas mass and density; then the adsorption test is carried out. The vacuum pump 115 of the air extraction module 106 evacuates the system for not less than 1 hour, and then methane and nitrogen are injected into each sample tank 112 to the corresponding target pressure by the gas injection module 104. The constant temperature box 101 maintains a stable temperature environment. After the adsorption equilibrium, the weighing balance 102 obtains the total mass of the sample tank 112, and the adsorbed gas mass is calculated by the difference between the total mass and the free gas mass. Finally, based on the adsorption amount data under different target pressures, an isothermal adsorption curve is drawn; during the whole process, one sample tank 112 corresponds to one target pressure point, and n sample tanks 112 and the reference tank 111 are tested synchronously, eliminating the cumulative error caused by the traditional step-by-step pressure increase, and realizing fast and accurate isothermal adsorption measurement.

[0033] In addition, the gravimetric isothermal adsorption device also includes a pressure relief pipe 117 and a fifth valve 118. The pressure relief pipe 117 is connected to the distribution pipe 103. The fifth valve 118 is installed on the pressure relief pipe 117. The pressure relief pipe 117 and the fifth valve 118 can be quickly opened after the experiment or when the system pressure is abnormal, so as to safely discharge the residual gas in the distribution pipe 103 and each of the sample placement modules 105, avoid high-pressure gas retention that may damage the equipment or affect subsequent operations, and ensure the safety and stability of the experimental system.

[0034] Finally, the computer 119 is electrically connected to the first valve 122, the second valve 123, the third valve 113, the fourth valve 116, the fifth valve 118, and the multiple weighing balances 102 via multiple data lines 120. The computer 119 automatically controls the first valve 122, the second valve 123, the third valve 113, the fourth valve 116, and the fifth valve 118. At the same time, the computer 119 collects the free gas mass data of the weighing balances 102 and the temperature and pressure data of the temperature and pressure sensors 114 at each pressure point. It automatically performs linear fitting through a built-in algorithm to calculate the free space volume. The entire process requires no manual intervention, which not only reduces human error but also greatly improves experimental efficiency and data consistency.

[0035] Second embodiment:

[0036] Based on the first embodiment, please refer to Figure 2 , Figure 2 This is a schematic diagram of the sample container structure of the second embodiment. The sample container 112 in this embodiment includes a sample container lid 201, a container body 202, a stainless steel tube 203, a piston 204, a filter head 205, and a stainless steel pipeline 206.

[0037] In this specific embodiment, the sample container lid 201 is connected to the weighing balance 102; the container body 202 is threadedly connected to the sample container lid 201; the stainless steel tube 203 is fixedly connected to the sample container lid 201 and extends into the container body 202; the piston 204 is fixedly connected to the stainless steel tube 203 and is located inside the container body 202; the filter head 205 is fixedly connected to the container body 202, located at the top of the container body 202, and communicates with the container body 202; the stainless steel pipeline 206 is fixedly connected to the filter head 205 and communicates with the filter head 205 and the sample container 112; an external thread is provided at the bottom of the container body 202. The sample container lid 201 is provided with an internal thread, which allows the container body 202 to be threadedly connected to the sample container lid 201. In use, the inner wall of the container body 202 is cleaned, and then the sample to be tested is placed in the container body 202. The piston 204 is inserted into the container body 202, and then the internal thread of the sample container lid 201 is screwed onto the external thread of the container body 202, thereby pushing the stainless steel tube 203 and the piston 204, so that the piston 204 presses the test sample. Then the container body 202 is placed in the constant temperature chamber 101, and the stainless steel pipeline 206 and the reference container 111 are connected through a quick connector. After the parameters stabilize, the isothermal adsorption test is performed.

[0038] The sample container 112 further includes a sealing ring 207, which is connected to the piston 204 and sleeved on the piston 204, located between the piston 204 and the container body 202. The sealing ring 207 is made of a high-pressure resistant and aging-resistant elastic material, and it fits tightly against the inner wall of the container body 202. During the process of the piston 204 pressing the test sample, it can effectively enhance the sealing performance of the container body 202, prevent gas from leaking from the gap between the piston 204 and the inner wall of the container body 202, ensure the pressure inside the container body 202 is stable, and avoid test errors caused by gas leakage.

[0039] On the other hand, the present invention also includes a gravimetric isothermal adsorption measurement method, which uses the aforementioned gravimetric isothermal adsorption device and includes the following steps:

[0040] S100: Crush the sample to be tested to the target particle size, weigh it, and then put it into the sample container.

[0041] Specifically, a coal sample with a particle size of 0.25mm to 0.18mm (60-80 mesh) is prepared. After the prepared coal sample is accurately weighed, it is quickly put into the container. The lid of the sample container is screwed on, so that the piston is at the top of the sample, reducing the free space volume inside the sample container.

[0042] S200: Place the sample container and reference container into the constant temperature chamber and connect the distribution pipe. Turn on the booster pump to fill the reference container and sample container with helium to the maximum experimental pressure. Monitor the pressure data. If the pressure is stable within 1 hour, the system is considered to be sealed successfully.

[0043] Specifically, based on the reservoir temperature or experimental requirements, the temperature of the constant temperature chamber is set and adjusted, and helium is filled into the reference tank and the sample tank through the booster pump to the maximum test pressure of the experiment; the pressure data of the reference tank and the sample tank are collected through the temperature and pressure sensor, and the pressure of the reference tank and the sample tank should remain stable for at least 1 hour, which is considered to be a good system airtightness.

[0044] S300: Each sample container corresponds to a target pressure. Multiple sample containers are filled with helium at no less than 6 different target pressures. The mass, temperature and pressure data of the sample container at each pressure point are recorded. Based on the linear relationship between the mass and density of free gas, the free space volume of each sample container is calculated by the slope.

[0045] Specifically, after zeroing the weighing balance, the first and second valves are opened, and the fourth and fifth valves are closed. Helium gas at the corresponding target pressure is then pumped into the reference tank and the sample tank from low to high pressure using the booster pump. Based on the highest adsorption pressure, the mass of free gas (m³) in the sample tank at each pressure point is measured. f ), temperature (T) f ) and pressure (P) f The pressure points should be no fewer than 6. The mass of free gas (m³) measured at each pressure point... f ) and density (ρ f To create an intersection plot, set the intercept of the linear fitting curve to zero; the slope of the curve represents the free space volume (V). f ).

[0046] Free gas mass calculation:

[0047] m f =V f ·ρ f

[0048] Where: m f ρ represents the mass of free gas, expressed in grams (g). f This refers to the density of free gas, expressed in grams per cubic centimeter (g / cm³).

[0049] S400: Turn on the vacuum pump to evacuate the reference tank, sample tank and pipeline to remove the gas, and inject methane and nitrogen into each sample tank to the preset target pressure. After the adsorption is balanced, weigh the total mass of the sample tank and calculate the adsorbed gas mass based on the difference between the total mass and the free gas mass.

[0050] Specifically, after the free space volume measurement is completed, the first valve and the fifth valve are closed, and the second valve and the fourth valve are opened. The vacuum pump is used to evacuate the gas from the reference container, the sample container, and the pipeline for at least one hour. Then, the weighing balance is zeroed. The fourth valve and the fifth valve are closed, and the first valve and the second valve are opened. The booster pump is used to inject adsorbed gases (methane and nitrogen) into the reference container and the sample container until the adsorption target pressure is reached. After adsorption equilibrium is achieved, the samples are weighed, and the pressure (P) of the sample container is recorded. r ), temperature (T) r ) and sample container mass (m r At this point, the weighing value is the sum of the mass of free gas and the mass of adsorbed gas corresponding to that pressure point.

[0051] Calculation of adsorbed gas mass m1:

[0052] m1 = m r -m f

[0053] In the formula: m1 is the mass of the adsorbed gas, in grams (g); m r It is the sum of the mass of free gas and the mass of adsorbed gas, expressed in grams (g).

[0054] Conversion between absolute adsorption capacity and relative adsorption capacity:

[0055]

[0056] In the formula: n is the molar volume of the gas, usually taken as a fixed value of 22.4, in liters per mole (L / mol); M is the molar mass of the gas, in grams per mole (g / mol); ρ f ρ is the density of the adsorbed gas at the current pressure point. s V is the density of the adsorbed gas phase; g V represents the volume of the adsorbed gas under standard conditions, in cubic centimeters (cm³); m represents the mass of the corresponding reference sample, in grams (g); ad This is the absolute adsorption capacity, expressed in cubic centimeters per gram (cm³ / g).

[0057] S500: Summarize the adsorption data under different target pressures and plot the isothermal adsorption curve of adsorption capacity as a function of pressure.

[0058] Specifically, one sample vessel corresponds to one target pressure adsorption point, and n sample vessels and n reference vessels can test the adsorption amount under n different target pressure conditions, thus obtaining the adsorption isotherm in one go.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) Compared with the volumetric isothermal adsorption device, the present invention does not involve the selection of gas state equation and the calculation of compressibility factor. Its test accuracy depends only on the accuracy of the balance, and the test error is easier to control.

[0061] (2) The sample container of the present invention can be freely adjusted in terms of capacity, thereby reducing free space volume and reducing test error.

[0062] (3) Compared with the existing gravimetric isothermal adsorption experimental apparatus, this experimental apparatus has the characteristics of being disposable, having a short testing time, and high precision;

[0063] (4) Compared with the gravimetric isothermal adsorption experimental apparatus, this experimental apparatus eliminates cumulative error, and one sample container is used to measure one adsorption target pressure point, thus eliminating the influence of the previous adsorption target pressure point on the next adsorption target pressure point.

[0064] (5) The present invention can realize fully automatic and high-precision isothermal adsorption, avoiding complex manual operation, making the test more accurate, convenient and fast.

[0065] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A gravimetric isothermic adsorption apparatus, characterized by, The device includes a constant temperature chamber, multiple weighing balances, a distribution tube, a gas injection module, multiple sample placement modules, a gas extraction module, and a control module. The multiple weighing balances are disposed inside the constant temperature chamber, the multiple sample placement modules are disposed on the multiple weighing balances, the distribution tube is connected to the multiple sample placement modules respectively, the gas injection module is used to deliver gas to the distribution tube, the gas extraction module is used to extract gas from the distribution tube, and the control module is connected to the gas extraction module, the sample placement modules, and the gas injection module. The air injection module includes an air source, a booster pump, and an air compressor. The air source and the booster pump are connected by a pipeline, and the air compressor and the booster pump are connected by a pipeline. A first valve is installed on the pipeline between the air compressor and the booster pump. The booster pump is connected to the distribution pipe by a pipeline, and a second valve is installed on the pipeline between the booster pump and the distribution pipe.

2. The gravimetric isothermal adsorption device as described in claim 1, characterized in that, The sample placement module includes a reference container, a sample container, a third valve, and a temperature and pressure sensor. The sample container is connected to the weighing balance. The two sides of the reference container are respectively connected to the distribution pipe and the sample container through pipelines. The third valve and the temperature and pressure sensor are installed on the pipeline between the reference container and the sample container.

3. The gravimetric isothermal adsorption device as described in claim 2, characterized in that, The air extraction module includes a vacuum pump and a fourth valve. The vacuum pump is connected to the distribution pipe via a pipeline. The fourth valve is located on the pipeline between the vacuum pump and the distribution pipe.

4. The gravimetric isothermal adsorption device as described in claim 3, characterized in that, The gravimetric isothermal adsorption device also includes a pressure relief pipeline and a fifth valve, wherein the pressure relief pipeline is connected to the distribution pipe; and the fifth valve is located on the pressure relief pipeline.

5. The gravimetric isothermal adsorption device as described in claim 4, characterized in that, The control module includes a computer and multiple data lines. The computer is electrically connected to the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and multiple weighing balances via the multiple data lines.

6. A gravimetric isothermal adsorption measurement method, employing the gravimetric isothermal adsorption apparatus as described in any one of claims 1-5, characterized in that, Includes the following steps: The sample to be tested is crushed to the target particle size, weighed, and then placed into a sample container. Place the sample container and reference container into the constant temperature chamber and connect the distribution pipe. Turn on the booster pump to fill the reference container and sample container with helium to the maximum experimental pressure. Monitor the pressure data. If the pressure is stable within 1 hour, the system is considered to be sealed. Each sample container corresponds to a target pressure. Multiple sample containers are filled with helium at no less than 6 different target pressures. The mass, temperature and pressure data of the sample containers at each pressure point are recorded. Based on the linear relationship between the mass and density of free gas, the free space volume of each sample container is calculated using the slope. Turn on the vacuum pump to evacuate the reference tank, sample tank and pipeline to remove the gas, and inject methane and nitrogen into each sample tank to the preset target pressure. After the adsorption is balanced, weigh the total mass of the sample tank and calculate the adsorbed gas mass based on the difference between the total mass and the free gas mass. Summarize the adsorption data under different target pressures and plot the isothermal adsorption curves of adsorption capacity as a function of pressure.

Images