A novel free-space controlled adsorption device and a method for calculating adsorption amount

Abstract

The application provides a novel free space controlled adsorption device and an adsorption amount calculation method, comprising: at least one test tube; at least one blank tube; a standard tube; a temperature sensor; a pressure sensor; a control system; a first free space control kit for adjusting the first free space of the test tube or the blank tube; and a second free space control kit for adjusting the second free space of the test tube or the blank tube. The application has the beneficial effect that the free space (the abbreviation of the first free space and the second free space) can be accurately adjusted and measured, the effective free space can be calculated and updated in real time throughout the whole process, the effective free space is not affected by environmental changes, advanced algorithms are used, the influence of non-ideal coefficients and complex background noise on the test can be effectively eliminated, the test is suitable for high and low temperature tests, and is also suitable for low pressure and high pressure tests, and the test repeatability and precision are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of analytical instruments, and in particular to a novel free-space controlled adsorption device and a method for calculating adsorption capacity. Background Technology

[0002] With the rapid development of materials science, including nanomaterials, energy storage materials, and catalytic materials, physical adsorption technology has been widely applied to the analysis of specific surface area, pore size distribution, and adsorption capacity of solid materials. Nitrogen and argon are commonly used analytical gases. To control the adsorption process step by step, the sample needs to be maintained at the phase transition temperature of the corresponding analytical gas. For example, when nitrogen is used as the analytical gas, the sample needs to be immersed in liquid nitrogen; when argon is used, the sample needs to be immersed in liquid argon. Throughout the analysis, the pressure needs to be continuously increased or decreased until adsorption equilibrium is reached. Using the gas equation, the adsorption capacity of the sample at different partial pressures at a constant temperature can be calculated, i.e., the isotherm. Then, different analytical models are used to analyze the isotherm to obtain information such as the specific surface area, pore size distribution, and adsorption capacity of the sample. Of course, physical adsorption includes both low-pressure and high-pressure physical adsorption, both requiring isotherms at the corresponding constant test temperature.

[0003] Unlike chemisorption, physical adsorption is a weak, non-selective adsorption process. Reaching adsorption equilibrium at each partial pressure requires a considerable amount of time, and isotherms often require data collection at multiple partial pressures. The more data collected, the more accurate the subsequent analysis results, but also the longer the analysis time. The volume of the test tube containing the sample, measured at room temperature, is the first free space; the volume measured at the test temperature (generally low, but can also be high), is the second free space. In this case, the test tube is partially submerged in the cryogenic liquid (such as liquid nitrogen or liquid argon) and partially above it. Calculating the amount of adsorption requires knowing the effective free space of the test tube, which is calculated from the first and second free spaces. Due to the lengthy analysis process and the gradual evaporation of the cryogenic liquid in the Dewar flask, the liquid level continuously drops, causing the second free space to change, which in turn affects the effective free space, introducing many uncertainties and difficulties into the calculation of the adsorption amount.

[0004] To address the aforementioned free space issue, existing main technologies include the porous material method and the constant-level method. Both methods require elevators and Dewar flasks. The porous material method involves wrapping a porous material around the test tube, with the elevator raising the Dewar flask to a fixed position. The cryogenic liquid inside the Dewar flask cools the test tube and the porous material. Because the cryogenic liquid evaporates, the liquid level drops. The porous material uses capillary action to draw the cryogenic liquid to its highest point, thus maintaining a constant second free space, and consequently, a constant effective free space. However, in practice, during long-term analysis, as the liquid level drops, more and more of the porous material inevitably detaches from the cryogenic liquid and becomes exposed, creating a temperature difference from top to bottom. This causes the actual second free space to shrink, resulting in a lower calculated adsorption capacity. The constant-level method uses a liquid level sensing system to control the elevator's movement, ensuring a constant volume of the test tube immersed in the cryogenic liquid. During the analysis, as the liquid level drops, the level sensor system cannot contact the liquid surface. The elevator slowly raises the Dewar flask until the level sensor contacts the cryogenic liquid surface, repeating this action to assume the second free space is fixed. However, in reality, as the Dewar flask rises, although the volume of the test tube immersed in the cryogenic liquid remains constant, the portion of the test tube extending into the Dewar flask but not submerged gradually increases. The temperature inside the Dewar flask is inevitably lower than room temperature, thus making the second free space actually larger and resulting in an overestimation of the adsorption capacity.

[0005] This invention aims to solve the problem that free space is easily affected by environmental factors such as liquid level position and room temperature changes. It can achieve precise adjustment and measurement of free space, and can calculate and update the effective free space in real time throughout the process. It is not affected by environmental changes on the effective free space. With the help of advanced algorithms, it can effectively eliminate the influence of non-ideal coefficients and complex background noise on the test. It is not only suitable for high and low temperature tests, but also for low and high pressure tests, which greatly improves the repeatability and accuracy of the test. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention discloses a novel free-space controlled adsorption device and a method for calculating the adsorption capacity. The technical solution of this invention is implemented as follows:

[0007] A novel free-space controlled adsorption device includes:

[0008] At least one test tube can be loaded with the sample to be tested and an adsorption experiment can be performed;

[0009] At least one blank tube is used to measure free space values ​​or calculate the amount of free gas;

[0010] The first free space control kit is used to adjust the first free space of the test tube or blank tube so that the first free space of the test tube and blank tube are consistent under normal temperature conditions.

[0011] The second free space control kit is used to adjust the second free space of the test tube or blank tube so that the second free space of the test tube and blank tube are consistent at the test temperature.

[0012] A standard tube, whose internal volume is known, is connected to a test tube and a blank tube via a valve to control the pressure inside the test tube and the blank tube.

[0013] Pressure sensors and temperature sensors are used to test pressure and temperature values;

[0014] The control system can receive information from temperature and pressure sensors, control the first free space control kit, the second free space control kit, and valves, and calculate the adsorption amount of the analyte based on the gas state equation and the received parameter information.

[0015] The test tube and the standard tube are connected by a pipe;

[0016] The blank tube is connected to the standard tube via a pipe;

[0017] The first free space control kit is connected to the test tube via a pipe;

[0018] The second free space control kit is connected to the test tube.

[0019] Preferably, the first free space control kit includes an adjustable space and an adjustment mechanism;

[0020] One end of the adjustable space is sealed and connected to the pipe that is connected to the blank tube or test tube, and the other end is connected to the adjustment mechanism;

[0021] The adjustment mechanism includes a power unit and a connecting device;

[0022] One end of the connecting device is connected to the adjustable space, and the other end is connected to the power device and controlled by the power device.

[0023] Preferably, the second free space control kit includes a slide and a motor;

[0024] The motor is connected to and controls the lifting and lowering of the slide, and the slide is connected to the test tube or the blank tube and controls the lifting and lowering of the test tube or the blank tube.

[0025] Preferably, the second free space control kit includes a slide table and a motor;

[0026] The motor is connected to and controls the lifting and lowering of the slide table;

[0027] A first magnetic body is provided on the slide table;

[0028] The test tube or the blank tube is provided with a filling rod inside, a second magnetic body is provided at the top of the filling rod, and a third magnetic body is provided above the top of the filling rod and is fixed to the second magnetic body by magnetic force.

[0029] The slide table controls the third magnetic body via the first magnetic body to drive the filling rod to rise and fall.

[0030] Preferably, the standard pipe is provided with a space control kit, the space control kit having the same structure as the first free space control kit, and the standard pipe and the space control kit are connected by a pipe.

[0031] A method for calculating adsorption capacity includes the following steps:

[0032] A1. Under normal temperature conditions, adjust the first free space of the test tube and the blank tube to be consistent;

[0033] A2. At the test temperature, adjust the second free space of the test tube and the blank tube to be consistent;

[0034] A3. Establish a gas volume of Qin_st in the standard tube;

[0035] A4. The gas diffuses into the test tube and reaches equilibrium. At this time, the amount of gas remaining in the standard tube is Qleft_st, and the amount of free gas in the test tube is Qfree_t.

[0036] A5. Re-establish the gas volume Qin_bl in the standard tube;

[0037] A6. The gas diffuses into the blank tube, and the pressure of the blank tube is adjusted to be consistent with that of the test tube through the needle valve or proportional valve. At this time, the amount of free gas in the blank tube is Qfree_bl, and the amount of remaining gas in the standard tube is Qleft_bl. Qfree_bl = Qfree_t = Qin_bl - Qleft_bl.

[0038] A7. Calculate the amount of gas adsorbed by the sample in the test tube, Qamount. According to the law of conservation of mass, the amount of gas adsorbed by the sample, Qamount, is equal to the amount of gas reduced in the standard tube (Qin_st - Qleft_st) minus the amount of free gas in the test tube, Qfree_t. Since Qfree_bl = Qfree_t, Qamount = Qin_st - Qleft_st - Qfree_bl.

[0039] A method for calculating adsorption capacity includes the following steps:

[0040] B1. Under normal temperature conditions, adjust the first free space of the test tube and the blank tube to be consistent, denoted as Vfs_ST;

[0041] B2. At the test temperature, adjust the second free space of the test tube and the blank tube to be the same, denoted as Vfs_AT;

[0042] B3. The effective free space Vfs of the test tube can be calculated based on the values ​​of Vfs_ST and Vfs_AT.

[0043]

[0044] In the formula: T at To test the temperature, T st The standard tube temperature is denoted by α, and α is a non-ideal coefficient.

[0045] B4. Establish a gas pressure of Pin_st in the standard tube;

[0046] B5. The gas diffuses into the test tube and reaches equilibrium. At this time, the gas pressure in the standard tube is Pleft_st, and the free gas pressure in the test tube is Pfree_t.

[0047] B6. The control system calculates the real-time second free space value Vfs_AT_va of the blank tube based on the real-time pressure value inside the blank tube. At this time, the second free space value inside the test tube is equal to the second free space value inside the blank tube. Based on the values ​​of Vfs_ST and Vfs_AT_va, the real-time effective free space Vfs_va of the test tube can be calculated according to the formula in step B3.

[0048] B7. The adsorption amount of the sample can be calculated based on the gas law and the law of conservation of mass. The adsorption amount Qamount equals the decrease in gas in the standard tube minus the amount of free gas in the test tube. The decrease in gas in the standard tube equals (Pin_st - Pleft_st) * Vm / (R * T) st The amount of free gas in the test tube is equal to Pfree_t*Vfs_va / (R*T). st ), so Qamount={(Pin_st-Pleft_st)*Vm-Pfree_t*Vfs_va} / (R*T st );

[0049] In the above formula: Vm is the volume of the standard tube; R is the gas constant; T st The temperature of the standard tube is Qamount; Qamount is the amount of adsorption on the sample.

[0050] By implementing the technical solution of this invention, through precise adjustment of the free space and real-time updating of the effective free space, coupled with an advanced adsorption capacity algorithm, adsorption testing can be made unaffected by environmental changes. Furthermore, it can effectively eliminate interference from non-ideal coefficients and complex background noise. It is suitable not only for high and low temperature testing, but also for low and high pressure testing, greatly improving the technical effect of test repeatability and accuracy. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Identical parts are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "bottom surface," "top surface," "inner," and "outer" refer to directions toward or away from the geometric center of a specific part, respectively.

[0053] Figure 1 This is a simplified structural diagram of Example 1 under test conditions;

[0054] Figure 2 This is a connection structure diagram of the second free space control kit and the test tube in Example 1;

[0055] Figure 3 This is a simplified structural diagram of Example 2 under test conditions;

[0056] Figure 4 This is a connection diagram of the second free space control kit and the test tube or blank tube in Example 2;

[0057] Figure 5 This is a cross-sectional view of the connection structure between the second free space control kit and the test tube or blank tube in Example 2;

[0058] Figure 6 This is a schematic diagram of the structure of the first free space control kit.

[0059] In the above figures, the figure numbers indicate the following:

[0060] 1. Test tube

[0061] 1-1, First connector

[0062] 2. Blank tube

[0063] 2-1, Second connector

[0064] 3. First Free Space Control Kit

[0065] 3-1, Extended Wall

[0066] 3-2, Sealing ring

[0067] 3-3, Rotating rod

[0068] 3-4, Adapter

[0069] 3-5, Threaded parts

[0070] 3-6, Fasteners

[0071] 4. Second Free Space Control Kit

[0072] 4-1, Motor

[0073] 4-2, slide

[0074] 4-3, First Magnetic Body

[0075] 4-4, Third Magnetic Body

[0076] 5. Standard pipe

[0077] 6. Air intake

[0078] 7. Cryogenic liquid storage device

[0079] 8. Filler rod

[0080] 8-1, Second Magnetic Body

[0081] Ptest, the first pressure sensor

[0082] Pblk, second pressure sensor

[0083] Pm, the third pressure sensor

[0084] Vt, the first valve

[0085] Vb, the second valve

[0086] Vout, the third valve

[0087] Vin, the fourth valve

[0088] Vratio, proportional valve Detailed Implementation

[0089] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0090] Example 1

[0091] In a specific embodiment 1, such as Figure 1 and Figure 2 As shown,

[0092] A novel free-space controlled adsorption device includes:

[0093] A test tube 1 can be loaded with the sample to be tested and an adsorption experiment can be performed;

[0094] A blank tube 2, unloaded with a sample, is used to measure free space values ​​or calculate the amount of free gas;

[0095] The first free space control kit is used to adjust the first free space of test tube 1 or blank tube 2 so that the first free space of test tube 1 and blank tube 2 are consistent under normal temperature conditions.

[0096] The second free space control kit is used to adjust the second free space of test tube 1 or blank tube 2 so that the second free space of test tube 1 and blank tube 2 are consistent at the test temperature.

[0097] The standard tube 5, whose internal volume is known, is connected to the test tube 1 and the blank tube 2 via a valve to control the pressure inside the test tube 1 and the blank tube 2; a temperature sensor is installed inside the standard tube 5 to test the temperature value.

[0098] The control system can receive information from temperature and pressure sensors, control the first free space control kit, the second free space control kit, and valves, and calculate the adsorption amount of the analyte based on the gas state equation and the received parameter information. In this embodiment, the control system is a computer connected to the adsorption device of this embodiment via a communication line.

[0099] Test tube 1 is connected to standard tube 5 via a pipe. A first valve Vt is installed on the pipe, and a first pressure sensor Ptest is installed below the first valve Vt to detect the internal pressure value of test tube 1. A first connector 1-1 is installed at the opening of test tube 1 to seal and connect test tube 1.

[0100] Blank tube 2 and standard tube 5 are connected by a pipeline. A proportional valve Vratio and a second valve Vb are installed on the pipeline in sequence. A second pressure sensor Pblk is installed below the second valve Vb to detect the internal pressure value of blank tube 2. A second connector 2-2 is installed at the opening of blank tube 2 to seal and connect blank tube 2.

[0101] Standard pipe 5 is connected to an external vacuum pump via a pipeline. A third valve Vout is installed on the pipeline. One end of standard pipe 5 is equipped with an air inlet 6 for connecting to an external gas tank. A fourth valve Vin is installed on the air inlet 6.

[0102] The third pressure sensor Pm is connected to the standard pipe 5 through a pipe and tests its internal pressure value.

[0103] The first free space control kit includes adjustable space and adjustment mechanisms;

[0104] One end of the adjustable space is sealed and connected to the pipe connecting the test tube 1 and the standard tube 5, and the other end is connected to the adjustment mechanism;

[0105] The regulating mechanism includes a power unit and a connecting device;

[0106] One end of the connecting device is connected to the adjustable space, and the other end is connected to the power device and controlled by the power device.

[0107] In this embodiment, the adjustable space is the area composed of the extension wall 3-1 and the sealing ring 3-2, the power device is a stepper motor (setting the step position through a stepper motor is a conventional technology, so it is not shown), and the connecting device includes a rotating rod 3-3, an adapter 3-4 and a threaded part 3-5.

[0108] The sealing ring 3-2 is disposed inside the extension wall 3-1;

[0109] The extension wall 3-1 is equipped with a fastener 3-6 inside;

[0110] Fixing element 3-6 defines the position of sealing ring 3-2;

[0111] The sealing ring 3-2 is limited by the fastener 3-6, adheres tightly to the extension wall 3-1, and is pressed by the adapter 3-4;

[0112] One side of the threaded part 3-5 is connected to one end of the rotating rod 3-3 by a thread; the inner wall of the other side of the threaded part 3-5 is provided with an internal thread, and the outer wall of the extension wall 3-1 is provided with a matching external thread; the threaded part 3-5 and the outer extension wall are connected by a thread.

[0113] The rotating rod 3-3 passes through the threaded part 3-5, the adapter 3-4, and the sealing ring 3-2 in sequence and is inserted into the inner wall of the outer extension.

[0114] The steps for using the first free space control kit are as follows:

[0115] By rotating the threaded part 3-5, the adapter 3-4 is subjected to force and enters the interior of the extension wall 3-1, and compresses the sealing ring 3-2 to achieve a seal.

[0116] Meanwhile, when the volume needs to be adjusted, the volume can be adjusted by twisting or pulling out the rotating rod 3-3.

[0117] The volume change value of the adjustable space is the volume change value when the rotating rod 3-3 is extended or pulled out.

[0118] The distance the rotating rod 3-3 can move, and whether it extends or extends out, can also be determined based on the required pressure value in the enclosed space.

[0119] Of course, this embodiment can also be implemented without using a stepper motor and instead use manual rotation. When using manual rotation, the user needs to observe the rotation distance.

[0120] Sealing rings 3-2 include, but are not limited to, rubber and polytetrafluoroethylene.

[0121] However, due to the friction between the rotating rod 3-3 and the threaded part 3-5, when adjusting the volume, the threaded part 3-5 may also rotate, causing the compressive force on the adapter 3-4 to change, and the compressive force on the sealing ring 3-2 to change, which may affect the sealing effect. Therefore, the adapter 3-4 is provided with an external thread, and the extension wall 3-1 is provided with an internal thread. The adapter 3-4 is connected to the extension wall 3-1 through the thread.

[0122] The advantage of this design is that even if the threaded part 3-5 and the rotating rod 3-3 rotate simultaneously, the compressive force on the adapter 3-4 will not change, so the compressive force applied to the sealing ring 3-2 will not change, thus maintaining the sealing effect of the sealing ring 3-2.

[0123] The second free space control kit includes a slide 4-2 and a motor 4-1;

[0124] Motor 4-1 connects to and controls the lifting and lowering of slide 4-2. Slide 4-2 connects to the first connector 1-1 on test tube 1 and controls the lifting and lowering of test tube 1.

[0125] The steps for calculating the adsorption amount using the device in this embodiment are as follows:

[0126] A1. Adjust the first free space of test tube 1 and blank tube 2 to be consistent under normal temperature conditions;

[0127] A1.1 Turn on the vacuum pump and evacuate the standard tube 5, test tube 1 and blank tube 2 for t1 time or to a certain pressure value. The evacuation time t1 can be set by the control system.

[0128] A1.2. Open the air inlet 6 and introduce inert gas that will not be adsorbed. Establish a certain pressure in the standard tube 5. After the pressure stabilizes, the pressure reading of the third pressure sensor Pm is Pst1, and the temperature sensor reading is T. st The volume of standard tube 5 has been calibrated before testing and is recorded as Vm;

[0129] A1.3. Open the second valve Vb and introduce inert gas into the blank tube 2 for a certain period of time. Then close the second valve Vb. When the reading of the second pressure sensor Pblk stabilizes, the pressure reading of the second pressure sensor Pblk is P. b1 The pressure reading of the third pressure sensor Pm is Pst2;

[0130] A1.4, Pst1, T st Vm, Pst2 and P b1 Substituting into the gas law and combining it with the law of conservation of mass, calculate the first free space Vfs_ST_bl in blank tube 2 at room temperature: Vfs_ST_bl=(Pst1-Pst2) / P b1 *Vm;

[0131] A1.5 Reopen the air inlet 6 and introduce inert gas to establish the same pressure Pst1 as in step A1.1 in the standard tube 5;

[0132] A1.6. Open the first valve Vt and let the inert gas flow into the test tube 1 for a certain period of time. Then close the first valve Vt. When the reading of the first pressure sensor Ptest stabilizes, the pressure reading of the first pressure sensor Ptest is P. t1 The pressure reading of the third pressure sensor Pm is Pst3;

[0133] A1.7, Pst1, T st Vm, Pst3 and P t1 Substituting into the gas law and the law of conservation of mass, calculate the first free space Vfs_ST_t of test tube 1 at room temperature: Vfs_ST_t = (Pst1 - Pst3) / P t1 *Vm;

[0134] A1.8 If Vfs_ST_t and Vfs_ST_bl are the same, proceed to the next step; if Vfs_ST_t and Vfs_ST_bl are not the same, control the first free space control kit on test tube 1, and the control system issues a command to make the stepper motor drive the rotating rod 3-3 to rotate, thereby changing the adjustable space and the reading of the first pressure sensor Ptest also changes accordingly. When the reading of the first pressure sensor Ptest is (P t1When *Vfs_ST_t / Vfs_ST_bl), the first free space value of test tube 1 is made consistent with that of blank tube 2.

[0135] A2. Adjust the second free space of test tube 1 and blank tube 2 to be consistent at the test temperature;

[0136] A2.1 Place test tube 1 and blank tube 2 into the cryogenic liquid storage device 7 corresponding to the test temperature;

[0137] A2.2 After the reading of the second pressure sensor Pblk stabilizes, record the pressure reading P at this moment. b2 Calculate the second free space Vfs_AT_bl of blank tube 2 under low temperature conditions: Vfs_AT_bl = Vfs_ST_bl * P b1 / P b2 ;

[0138] A2.3 Record the reading P of the first pressure sensor Ptest at this time. t2 Calculate the second free space Vfs_AT_t of test tube 1 under low temperature conditions: Vfs_AT_t = P t1 *Vfs_ST_t / P t2 ;

[0139] A2.4 If Vfs_AT_t and Vfs_AT_bl are consistent, proceed to the next step; if they are inconsistent, the control system controls the second free space control kit on test tube 1, causing motor 4-1 to control slide 4-2 to rise or fall, thus raising or lowering test tube 1 and achieving pressure change in test tube 1. When the reading of the first pressure sensor Ptest is (P t2 When *Vfs_AT_t / Vfs_AT_bl), the second free space of test tube 1 and blank tube 2 are made consistent.

[0140] A3. Establish a test gas volume of Qin_st into standard tube 5;

[0141] A3.1. Turn on the vacuum pump to evacuate the standard tube 5, test tube 1 and blank tube 2;

[0142] A3.2. Open the air inlet 6 to introduce adsorbed gas, establishing a certain pressure of adsorbed gas in the standard tube 5; at this time, the pressure reading of the third pressure sensor Pm is Pst4, and the gas volume in the standard tube 5 is Qin_st=Pst4*Vm / (R*T) st );

[0143] A4. Gas is introduced into test tube 1 through standard tube 5;

[0144] Open the first valve Vt and allow the adsorbed gas to pass through test tube 1 for a period of time, then close the first valve Vt. Once the reading of the first pressure sensor Ptest stabilizes, the pressure reading of the first pressure sensor Ptest will be P. t3 The pressure reading of the third pressure sensor Pm is Pst5. At this time, the amount of gas remaining in the standard tube 5 is Qleft_st = Pst5 * V. m / (R*T st The amount of free gas in test tube 1 is Qfree_t;

[0145] A5. Re-establish the gas volume Qin_bl in standard tube 5;

[0146] A5.1. Open the air inlet 6 to establish a pressure of Pm equal to Pbl1 in the standard tube 5. At this time, the gas volume in the standard tube 5 is Qin_bl = Pbl1 * Vm / (R * T). st )

[0147] A5.2. Open the second valve Vb, and by adjusting the proportional valve Vratio to a certain degree of opening, slowly diffuse the adsorbed gas from the standard tube 5 to the blank tube 2, so that the pressure in the blank tube 2 is consistent with that in the test tube 1.

[0148] Another way to implement this step is to add a space control kit to the standard tube 5. The added space control kit has the same structure as the first free space control kit. The implementation method is that when the second valve Vb is opened, the standard tube 5 and the blank tube 2 are connected. The space control kit is used to adjust the space of the standard tube so that the gas pressure in the standard tube 5 and the blank tube 2 is adjustable, so that the pressure in the blank tube 2 is consistent with that in the test tube 1.

[0149] When the pressure reading of the second pressure sensor Pblk matches the pressure reading of the first pressure sensor Ptest, the second valve Vb is closed. At this time, the gas volume in the blank tube 2 is Qfree_bl, the remaining gas volume in the standard tube 5 is Qleft_bl, and the pressure reading of the third pressure sensor Pm is Pbl2. Qleft_bl = Pbl2 * Vm / (R * T) st According to the law of conservation of mass, Qfree_bl = Qin_bl - Qleft_bl

[0150] Since the equilibrium pressure in blank tube 2 and test tube 1 is the same, and their free space is the same, the amount of free gas in blank tube 2 (Qfree_bl) is equal to the amount of free gas in test tube 1 (Qfree_t), that is, Qfree_t = Qfree_bl.

[0151] A6. Calculate the adsorption amount Qamount of the sample in test tube 1, which is equal to Qin_st - Qleft_st - Qfree_t.

[0152] According to the data in A5, since Qfree_t = Qfree_bl, Qamount = Qin_st - Qleft_st - Qfree_bl.

[0153] A7. Repeat steps A3 to A6 above to calculate the adsorption amount corresponding to different equilibrium pressures in test tube 1.

[0154] This example demonstrates the adsorption capacity test of a low-temperature sample.

[0155] The free space of test tube 1 and blank tube 2 can be kept consistent, eliminating the need for unrealistic assumptions. For low-temperature testing, the requirement to maintain a constant liquid level is no longer necessary, as this is impossible. The requirements for the Dewar flask can be relaxed, reducing costs. Low-temperature liquid can be added midway to increase the testing time, and the calculation of adsorption amount does not need to consider non-ideal coefficients. Regardless of whether it is a low-pressure or high-pressure test, the influence of changes in the surrounding environment on the test results will be subtracted by blank tube 2, thereby improving the anti-interference ability.

[0156] Example 2

[0157] In a specific embodiment 2, such as Figure 3 , Figure 4 and Figure 5 As shown,

[0158] A novel free-space controlled adsorption device includes:

[0159] A test tube 1 can be loaded with the sample to be tested and an adsorption experiment can be performed;

[0160] A blank tube 2, unloaded with a sample, is used to measure free space values ​​or calculate the amount of free gas;

[0161] The first free space control kit is used to adjust the first free space of test tube 1 or blank tube 2 so that the first free space of test tube 1 and blank tube 2 are consistent under normal temperature conditions.

[0162] The second free space control kit is used to adjust the second free space of test tube 1 or blank tube 2 so that the second free space of test tube 1 and blank tube 2 are consistent at the test temperature.

[0163] The standard tube 5, whose internal volume is known, is connected to the test tube 1 and the blank tube 2 via a valve to control the pressure inside the test tube 1 and the blank tube 2; a temperature sensor is installed inside the standard tube 5 to test the temperature value.

[0164] The control system can receive information from temperature and pressure sensors, control the first free space control kit, the second free space control kit, and valves, and calculate the adsorption amount of the analyte based on the gas state equation and the received parameter information. In this embodiment, the control system is a computer connected to the adsorption device of this embodiment via a communication line.

[0165] Test tube 1 is connected to standard tube 5 by a pipe. A first valve Vt is installed on the pipe. A first pressure sensor Ptest is installed below the first valve Vt to detect the internal pressure value of test tube 1. A first connector 1-1 is installed at the opening of test tube 1 to seal test tube 1.

[0166] Blank tube 2 and standard tube 5 are connected by a pipe. A second valve Vb is installed on the pipe. A second pressure sensor Pblk is installed below the second valve Vb to detect the internal pressure value of blank tube 2. A second connector 2-2 is installed at the opening of blank tube 2 to seal and connect blank tube 2.

[0167] Standard pipe 5 is connected to an external vacuum pump via a pipeline. A third valve Vout is installed on the pipeline. One end of standard pipe 5 is equipped with an air inlet 6 for connecting to an external gas tank. A fourth valve Vin is installed on the air inlet 6.

[0168] The third pressure sensor Pm is connected to the standard pipe 5 through a pipe and tests its internal pressure value.

[0169] The first free space control kit includes adjustable space and adjustment mechanisms;

[0170] One end of the adjustable space is sealed and connected to the pipe connecting the test tube 1 and the standard tube 5, and the other end is connected to the adjustment mechanism;

[0171] The regulating mechanism includes a power unit and a connecting device;

[0172] One end of the connecting device is connected to the adjustable space, and the other end is connected to the power device and controlled by the power device.

[0173] In this embodiment, the adjustable space is the area composed of the extension wall 3-1 and the sealing ring 3-2, the power device is a stepper motor (not shown in conventional technology), and the connecting device includes a rotating rod 3-3, an adapter 3-4 and a threaded part 3-5;

[0174] The sealing ring 3-2 is disposed inside the extension wall 3-1;

[0175] The extension wall 3-1 is equipped with a fastener 3-6 inside;

[0176] Fixing element 3-6 defines the position of sealing ring 3-2;

[0177] The sealing ring 3-2 is limited by the fastener 3-6, adheres tightly to the extension wall 3-1, and is pressed by the adapter 3-4;

[0178] One side of the threaded part 3-5 is connected to one end of the rotating rod 3-3 by a thread; the inner wall of the other side of the threaded part 3-5 is provided with an internal thread, and the outer wall of the extension wall 3-1 is provided with a matching external thread; the threaded part 3-5 and the outer extension wall are connected by a thread.

[0179] The rotating rod 3-3 passes through the threaded part 3-5, the adapter 3-4, and the sealing ring 3-2 in sequence and is inserted into the inner wall of the outer extension.

[0180] The steps for using the first free space control kit are as follows:

[0181] By rotating the threaded part 3-5, the adapter 3-4 is subjected to force and enters the interior of the extension wall 3-1, and compresses the sealing ring 3-2 to achieve a seal.

[0182] Meanwhile, when the volume needs to be adjusted, the volume can be adjusted by twisting or pulling out the rotating rod 3-3.

[0183] The volume change value of the adjustable space is the volume change value when the rotating rod 3-3 is extended or pulled out.

[0184] The distance the rotating rod 3-3 can move, and whether it should be inserted or withdrawn, can also be determined based on the required pressure value in the enclosed space.

[0185] Of course, this embodiment can also be implemented without using a stepper motor and instead use manual rotation. When using manual rotation, the user needs to observe the rotation distance.

[0186] The sealing rings 3-2 include, but are not limited to, rubber or polytetrafluoroethylene materials.

[0187] However, due to the friction between the rotating rod 3-3 and the threaded part 3-5, when adjusting the volume, the threaded part 3-5 may also rotate, causing the compressive force on the adapter 3-4 to change, and the compressive force on the sealing ring 3-2 to change, which may affect the sealing effect. Therefore, the adapter 3-4 is provided with an external thread, and the extension wall 3-1 is provided with an internal thread. The adapter 3-4 is connected to the extension wall 3-1 through the thread.

[0188] The advantage of this design is that even if the threaded part 3-5 and the rotating rod 3-3 rotate simultaneously, the compressive force on the adapter 3-4 will not change, so the compressive force applied to the sealing ring 3-2 will not change, thus maintaining the sealing effect of the sealing ring 3-2.

[0189] The second free space control kit includes a slide 4-2 and a motor 4-1;

[0190] A first magnetic body 4-3 is provided on the slide table 4-2;

[0191] A filling rod 8 is provided inside the test tube 1 or the blank tube 2. A second magnetic body 8-1 is provided at the top of the filling rod 8. A third magnetic body 4-4 is provided above the top of the filling rod 8 and is fixed to the second magnetic body 8-1 by magnetic force.

[0192] The slide table 4-2 controls the third magnetic body 4-4 through the first magnetic body 4-3 to drive the filling rod 8 to rise and fall.

[0193] In this embodiment, a second free space control kit is also provided on the blank tube 2, and a filling rod 8 is also provided inside. The motor 4-1 and the slide 4-2 are not shown in the figure. Its connection structure is completely consistent with the structure of the second free space control kit in the test tube 1.

[0194] In this embodiment, the first magnetic body 4-3, the second magnetic body 8-1, and the third magnetic body 4-4 are all magnets. In this invention, the first magnetic body 4-3, the second magnetic body 8-1, and the third magnetic body 4-4 can also be iron or other materials that can be attracted by other magnetic bodies. The main effect is to allow the filling rod to move up and down under the control of the first magnetic body 4-3.

[0195] The steps for calculating the adsorption amount using the device in this embodiment are as follows:

[0196] B1. Adjust the first free space of test tube 1 and blank tube 2 to be consistent under normal temperature conditions;

[0197] B1.1 Turn on the vacuum pump and evacuate the standard tube 5, test tube 1 and blank tube 2 for t1 time or to a certain pressure value. The evacuation time t1 can be set by the control system.

[0198] B1.2. Open the air inlet 6 and introduce inert gas that will not be adsorbed. Establish a certain pressure in the standard tube 5. After the pressure stabilizes, the pressure reading of the third pressure sensor Pm is Pst1, and the temperature sensor reading is T. st The volume of standard tube 5 has been calibrated before testing and is recorded as Vm;

[0199] B1.3. Open the second valve Vb and introduce inert gas into the blank tube 2 for a certain period of time. Then close the second valve Vb. When the reading of the second pressure sensor Pblk stabilizes, the pressure reading of the second pressure sensor Pblk is P. b1 The pressure reading of the third pressure sensor Pm is Pst2;

[0200] B1.4, Pst1, T st Vm, Pst2 and P b1Substituting into the gas law and combining it with the law of conservation of mass, calculate the first free space Vfs_ST_bl in blank tube 2 at room temperature: Vfs_ST_bl=(Pst1-Pst2) / P b1 *Vm;

[0201] B1.5. Reopen the air inlet 6 and introduce inert gas to establish the same pressure Pst1 as in step A1.1 in the standard tube 5.

[0202] B1.6. Open the first valve Vt and let the inert gas flow into the test tube 1 for a certain period of time. Then close the first valve Vt. When the reading of the first pressure sensor Ptest stabilizes, the pressure reading of the first pressure sensor Ptest is P. t1 The pressure reading of the third pressure sensor Pm is Pst3;

[0203] B1.7, Pst1, T st Vm, Pst3 and P t1 Substituting into the gas law and the law of conservation of mass, the first free space Vfs_ST_t of test tube 1 at room temperature is calculated as follows: Vfs_ST_t=(Pst1-Pst3) / P t1 *Vm;

[0204] B1.8 If Vfs_ST_t and Vfs_ST_bl are the same, proceed to the next step; if Vfs_ST_t and Vfs_ST_bl are not the same, control the first free space control kit on test tube 1, and the control system issues a command to make the stepper motor drive the rotating rod 3-3 to rotate, thereby changing the adjustable space and the reading of the first pressure sensor Ptest also changes accordingly. When the reading of the first pressure sensor Ptest is (P t1 *Vfs_ST_t / Vfs_ST_bl), thereby ensuring that the first free space values ​​of test tube 1 and blank tube 2 are consistent.

[0205] B2. Adjust the second free space of test tube 1 and blank tube 2 to be consistent at the test temperature;

[0206] B2.1 Place test tube 1 and blank tube 2 into the cryogenic liquid storage device 7 corresponding to the test temperature;

[0207] B2.2 After the reading of the second pressure sensor Pblk stabilizes, record the pressure reading P at this moment. b2 Calculate the second free space Vfs_AT_bl of blank tube 2 under low temperature conditions: Vfs_AT_bl = Vfs_ST_bl * P b1 / P b2 ;

[0208] B2.3 Record the reading P of the first pressure sensor Ptest at this time. t2 Calculate the second free space Vfs_AT_t of test tube 1 under low temperature conditions, where Vfs_AT_t = P t1 *Vfs_ST_t / P t2 ;

[0209] B2.4 If Vfs_AT_t and Vfs_AT_bl are consistent, proceed to the next step; if they are inconsistent, the control system controls the second free space control kit on test tube 1, causing motor 4-1 to control the slide 4-2 to rise or fall, thereby causing the filling rod 8 inside test tube 1 to rise or fall, thus achieving pressure change in test tube 1. When the reading of the first pressure sensor Ptest is (P t2 *Vfs_AT_t / Vfs_AT_bl), thereby ensuring that the second free space of test tube 1 and blank tube 2 are consistent;

[0210] B3. The effective free space Vfs of the test tube can be calculated based on the values ​​of Vfs_ST and Vfs_AT.

[0211]

[0212] In the formula: T at To test the temperature, T st The standard tube temperature is denoted by α, and α is a non-ideal coefficient.

[0213] B4. Establish a gas flow rate of Qin_st into standard tube 5;

[0214] B4.1. Turn on the vacuum pump to evacuate the standard tube 5 and test tube 1, while keeping the blank tube 2 at the current pressure.

[0215] B4.2. Open the air inlet 6 to introduce adsorbed gas, establishing a certain pressure of adsorbed gas in the standard tube 5; at this time, the pressure reading of the third pressure sensor Pm is Pin_st, and the gas volume in the standard tube 5 is Qin_st = Pin_st * Vm / (R * T) st );

[0216] B5. Inject gas into test tube 1 through standard tube 5;

[0217] After opening the first valve Vt and introducing the adsorbed gas into test tube 1 for a period of time, the first valve Vt is closed. When the reading of the first pressure sensor Ptest stabilizes, the pressure reading of the first pressure sensor Ptest is Pfree_t; the pressure reading of the third pressure sensor Pm is Pleft_st. At this time, the amount of gas remaining in the standard tube 5 is Qleft_st = Pleft_st * V. m / (R*T stThe amount of free gas in test tube 1 is Qfree_t;

[0218] B6. The control system calculates the second free space value of blank tube 2 in real time based on the real-time pressure value of blank tube 2, denoted as Vfs_AT_va. At this time, the second free space value in test tube 1 is equal to the second free space value in blank tube 2. According to the values ​​of Vfs_ST, Vfs_AT_va and the formula at B3, the real-time effective free space Vfs_va of the test tube can be calculated. Therefore, the amount of free gas in test tube 1 is Qfree_t=(P t3 *Vfs_va) / (R*T st );

[0219] B7. Calculate the adsorption amount Qamount of the sample;

[0220] After air intake, the total air volume (Qdose) from standard tube 5 to test tube 1 is: Qin_st - Qleft_st

[0221] According to the equation of state for gases and the law of conservation of mass, we know that:

[0222] Qamount=Qdose-Qfree_t={(Pin_st-Pleft_st)*Vm-Pfree_t*Vfs_va} / (R*T st )

[0223] In the above formula: Vm is the volume of standard tube 5; R is the gas constant; T st The temperature of standard tube 5.

[0224] B8. Repeat steps B3 to B7 above to calculate the adsorption amount corresponding to different equilibrium pressures in test tube 1.

[0225] This example demonstrates the adsorption capacity test of a low-temperature sample.

[0226] The free space of test tube 1 and blank tube 2 can be kept consistent, eliminating the need for unrealistic assumptions. For low-temperature testing, the requirement to maintain a constant liquid level is no longer necessary, as this is impossible. The requirements for the Dewar flask can be relaxed, reducing costs. Low-temperature liquid can also be added midway through the test, increasing the testing time. Regardless of whether it is a low-pressure or high-pressure test, the impact of changes in the surrounding environment on the effective free volume will be subtracted by blank tube 2, thereby improving the anti-interference capability.

[0227] This invention includes two second free space control kits for test tubes, which can realize two second free space adjustment methods and can be selected according to actual needs.

[0228] This invention allows for the addition of multiple test tubes and multiple blank tubes according to actual testing needs. When there are multiple test tubes, the sample to be tested can be taken out from a certain test tube according to actual needs. At this time, the test tube can also be used as a blank tube, and the structure of the blank tube is exactly the same as that of the test tube.

[0229] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating adsorption capacity, employing a novel free-space controlled adsorption device, characterized in that, The novel free-space controlled adsorption device includes: At least one test tube can be loaded with the sample to be tested and an adsorption experiment can be performed; At least one blank tube is used to measure free space values ​​or calculate the amount of free gas; The first free space control kit is used to adjust the first free space of the test tube or blank tube so that the first free space of the test tube and blank tube are consistent under normal temperature conditions. The second free space control kit is used to adjust the second free space of the test tube or blank tube so that the second free space of the test tube and blank tube are consistent at the test temperature. A standard tube, whose internal volume is known, is connected to a test tube and a blank tube via a valve to control the pressure inside the test tube and the blank tube. Pressure sensors and temperature sensors are used to test pressure and temperature values; The control system can receive information from temperature and pressure sensors, control the first free space control kit, the second free space control kit, and valves, and calculate the adsorption amount of the analyte based on the gas state equation and the received parameter information. The test tube and the standard tube are connected by a pipe; The blank tube is connected to the standard tube via a pipe; The first free space control kit is connected to the test tube via a pipe; The second free space control kit is connected to the test tube; The method for calculating the adsorption capacity includes the following steps: A1. Under normal temperature conditions, adjust the first free space of the test tube and the blank tube to be consistent; A2. At the test temperature, adjust the second free space of the test tube and the blank tube to be consistent; A3. Establish a gas volume of Qin_st in the standard tube; A4. The gas diffuses into the test tube and reaches equilibrium. At this time, the amount of gas remaining in the standard tube is Qleft_st, and the amount of free gas in the test tube is Qfree_t. A5. Re-establish the gas volume Qin_bl in the standard tube; A6. The gas diffuses into the blank tube, and the pressure in the blank tube is adjusted to match that in the test tube via a valve. At this point, the amount of free gas in the blank tube is Qfree_bl, and the amount of residual gas in the standard tube is Qleft_bl. Qfree_bl=Qfree_t=Qin_bl-Qleft_bl; A7. Calculate the amount of gas adsorbed in the test tube, Qamount, which is equal to the amount of gas reduced in the standard tube, Qin_st - Qleft_st, minus the amount of free gas in the test tube, Qfree_t. Since Qfree_bl = Qfree_t, Qamount = Qin_st - Qleft_st - Qfree_bl. or, B1. Under normal temperature conditions, adjust the first free space of the test tube and the blank tube to be consistent, denoted as Vfs_ST; B2. At the test temperature, adjust the second free space of the test tube and the blank tube to be the same, denoted as Vfs_AT; B3. The effective free space Vfs of the test tube can be calculated based on the values ​​of Vfs_ST and Vfs_AT. B4. Establish a gas pressure of Pin_st in the standard tube; B5. The gas diffuses into the test tube and reaches equilibrium. At this time, the gas pressure in the standard tube is Pleft_st, and the free gas pressure in the test tube is Pfree_t. B6. The control system calculates the real-time second free space value Vfs_AT_va of the blank tube based on the real-time pressure value inside the blank tube. At this time, the second free space value inside the test tube is equal to the second free space value inside the blank tube. The real-time effective free space Vfs_va of the test tube can be calculated based on the values ​​of Vfs_ST and Vfs_AT_va. B7. The adsorption amount of the sample can be calculated based on the gas law and the law of conservation of mass. The adsorption amount Qamount equals the decrease in gas in the standard tube minus the amount of free gas in the test tube. The decrease in gas in the standard tube equals (Pin_st - Pleft_st) * Vm / (R * T) st The amount of free gas in the test tube is equal to Pfree_t*Vfs_va / (R*T). st ), so Qamount={(Pin_st-Pleft_st)*Vm-Pfree_t*Vfs_va} / (R*T st ); In the above formula: Vm is the volume of the standard tube; R is the gas constant; T st The temperature of the standard tube is Qamount; Qamount is the amount of adsorption on the sample.

2. The method according to claim 1, characterized in that, The first free space control kit includes an adjustable space and an adjustment mechanism; One end of the adjustable space is sealed and connected to the pipe connected to the blank tube or test tube, and the other end is connected to the adjustment mechanism; The adjustment mechanism includes a power unit and a connecting device; One end of the connecting device is connected to the adjustable space, and the other end is connected to the power device and controlled by the power device.

3. The method according to claim 2, characterized in that, The second free space control kit includes a slide and a motor; The motor is connected to and controls the lifting and lowering of the slide, and the slide is connected to the test tube or the blank tube and controls the lifting and lowering of the test tube or the blank tube.

4. The method according to claim 2, characterized in that, The second free space control kit includes a slide and a motor; The motor is connected to and controls the lifting and lowering of the slide table; A first magnetic body is provided on the slide table; The test tube or the blank tube is provided with a filling rod inside, a second magnetic body is provided at the top of the filling rod, and a third magnetic body is provided above the top of the filling rod and is fixed to the second magnetic body by magnetic force. The slide table controls the third magnetic body via the first magnetic body to drive the filling rod to rise and fall.

5. The method according to any one of claims 3 or 4, characterized in that, The standard pipe is equipped with a space control kit, which has the same structure as the first free space control kit. The standard pipe and the space control kit are connected by a pipe.

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