A gas dynamic adsorption testing device and a testing method thereof

Abstract

The application discloses a kind of gas dynamic adsorption testing device and its testing method, belong to measurement and testing technical field.The device is by gas steel bottle, mass flow meter, adsorption reaction column, four-way valve, tubular resistance heating furnace, thermal conductivity detector, data logger and pipeline, valve and pressure gauge connected between them are constituted, the adsorption testing of adsorbent under dynamic condition can be carried out using the above structure, the breakthrough curve of adsorbent is measured, and the adsorption capacity of adsorbent is quantitatively calculated using external standard method.The application testing structure is simple, easy to operate, low in cost, and can efficiently and accurately detect the adsorption amount of sample to gas without changing the material properties of experimental sample.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of measurement and testing, and particularly relates to a gas dynamic adsorption testing device and a testing method thereof. BACKGROUND

[0002] Adsorption refers to the phenomenon of molecules of a substance adhering to the surface or interface of a solid. The solid surface has surface tension and surface Gibbs free energy, which can spontaneously attract gas molecules to the surface to reduce the degree of force asymmetry of the solid surface molecules, thereby reducing the surface tension and Gibbs free energy. Adsorption can be divided into physical adsorption and chemical adsorption. In physical adsorption, the intermolecular force is van der Waals force, while in chemical adsorption, the combination is through chemical bonds. Adsorption has a wide range of applications in many fields, such as catalysis, separation, sensors, etc.

[0003] Traditional gas adsorption testing devices usually use a static method for experiments, i.e. a certain amount of gas is left to stand for a period of time at a certain temperature, and then the amount of gas adsorbed on the surface of the material is measured. The accuracy of the measurement results of this method is limited by the experimental conditions, and the dynamic process of gas adsorption cannot be studied. In contrast, dynamic adsorption testing devices can measure the amount of gas adsorbed on the surface of the material and the adsorption rate in real time, providing more accurate data.

[0004] Dynamic adsorption testing devices are experimental instruments commonly used to study the adsorption properties of material surfaces. They control the flow and temperature of the gas to cause adsorption on the surface of the material, and then measure the amount of gas adsorbed on the surface of the material, the adsorption rate, and other parameters in real time. This technology has a wide range of applications in the study of various materials. For example, in the study of catalysts, dynamic adsorption testing devices can be used to measure the amount of a specific gas adsorbed by a catalyst to evaluate the activity and stability of the catalyst. In the study of various nanomaterials, dynamic adsorption testing devices can be used to measure parameters such as the pore structure and surface area of the material. Currently, chemical adsorption instruments generally include a gas inlet system, a catalytic reactor, and a gas analyzer, of which the gas analyzer is usually a mass spectrometer or a chromatograph. However, there are some problems when using a mass spectrometer as a gas analyzer. First, mass spectrometers are expensive, and most laboratories cannot afford them. Second, mass spectrometers need to work in a high vacuum environment, so the sample size is small, and a capillary flow splitting method is usually used. The actual sample size is easily affected by external factors such as flow rate and pressure, making it difficult to accurately quantify, so it is usually used for qualitative and semi-quantitative analysis. When using a gas chromatograph as a gas analyzer, a chromatographic column is needed for separation, which can cause the measured signal to have a lag. SUMMARY

[0005] In view of this, the purpose of the present application is to provide a dynamic adsorption testing device and a testing method thereof, which can measure the adsorption amount and adsorption rate of gas on the surface of a material in real time; the measured data is closer to the real adsorption-desorption process, and more accurate data is provided for the engineering design process; the testing device has a simple structure, is easy to operate, and has a low manufacturing cost.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The present application provides a gas dynamic adsorption testing device, which mainly comprises n (n is an integer greater than or equal to 1) gas cylinders containing different gases (for example, gas cylinder A, gas cylinder B and gas cylinder C), mass flow controllers (for example, MFC1, MFC2 and MFC3), a buffer tank, an adsorption reaction column, a four-way valve, a tubular resistance furnace, a thermal conductivity detector and a data recorder, the outlets of the gas cylinders containing different gases are connected to the buffer tank through pipelines, and a switch valve (for example, K1, K2 and K3) and a mass flow controller (for example, MFC1, MFC2 and MFC3) are sequentially arranged on the outlet pipeline of each gas cylinder, the outlet of the buffer tank is connected to the first port of the four-way valve through a pipeline, the second port of the four-way valve is connected to the inlet of the adsorption reaction column through a pipeline, the adsorbent to be measured is filled in the adsorption reaction column, the outlet of the adsorption reaction column is connected to the thermal conductivity detector through a pipeline, the thermal conductivity detector is connected to the data recorder, the adsorption reaction column is placed in the tubular resistance furnace, an auxiliary gas cylinder (gas D) is connected to a switch valve (K4) through a pipeline, the outlet end of the switch valve is branched into pipeline I and pipeline II, pipeline I is connected to a mass flow controller (MFC4), the outlet of the mass flow controller is connected to the reference gas inlet of the thermal conductivity detector, and pipeline II is connected to the fourth port of the four-way valve through a mass flow controller (MFC5).

[0008] The first port and the second port of the four-way valve are connected, and a sample injection mode is formed.

[0009] The second port and the fourth port of the four-way valve are connected, and a purge mode is formed.

[0010] Based on the above technical solution, the outlet end of each switch valve is provided with a pressure gauge.

[0011] Based on the above technical solution, n is equal to 2, and the gas cylinders containing different gases are high-purity CO2 gas cylinders and high-purity N2 gas cylinders.

[0012] Based on the above technical solution, when the adsorbent is filled in the adsorption reaction column, the upper and lower ends are supported by quartz wool or a stainless steel sieve plate.

[0013] Based on the above technical scheme, further, the temperature control range of the tubular resistance heating furnace is 30-500 DEG C.

[0014] Based on the above technical scheme, further, the adsorption reaction column has a fixed volume, and the material of the adsorption reaction column is one of stainless steel and quartz glass.

[0015] The application also provides a test method of the gas dynamic adsorption test device, comprising the following steps:

[0016] (5) the device is adjusted to a purge mode, the tubular resistance heating furnace is heated, and the gas adsorbed on the surface of the adsorption reaction column and the adsorbent is removed;

[0017] (6) the tubular resistance heating furnace is lowered to a test temperature, and the device is adjusted to a sample injection mode;

[0018] (7) the gas breakthrough curve is recorded by the thermal conductivity detector and the data recorder until the signal after breakthrough remains stable;

[0019] (8) the relationship between the thermal conductivity detector signal value and the gas concentration is obtained by using an external standard method, and the adsorption amount Q of the adsorbent to the adsorption gas is calculated by the following formula:

[0020]

[0021] In the formula, Q is the saturated adsorption amount of unit mass of the adsorbent to the gas, mmol / g; C0 is the inlet gas mass concentration, %; Ci is the outlet gas mass concentration after i minutes of adsorption start, %; F is the total gas flow, mL / min; t b is the adsorption breakthrough time (C i / C0=5%), min; t s is the adsorption saturation time (C i / C0=100%), min; m is the filling amount of the adsorbent (the mass difference before and after the adsorbent is filled into the glass tube and activated), g; T is the adsorption temperature (K); T0 is 273 K, and V m is the molar volume of the gas under standard conditions (mL / mmol).

[0022] Based on the above technical scheme, further, the heating temperature in step (1) is lower than the decomposition temperature of the adsorbent by 30-50 DEG C, and the maintenance time is more than 1 h.

[0023] Based on the above technical scheme, further, the purge gas used in step (1) is an inert gas that does not react with the adsorbent material, and is one or a combination of more than two of N2, He and Ar.

[0024] Based on the above technical scheme, further, the test temperature in step (2) is 30-100 DEG C.

[0025] Compared with the prior art, the device and method of the present application have the following advantages:

[0026] 1. The test device in the present application has simple structure, convenient operation and low manufacturing cost.

[0027] 2. The present application can measure the adsorption amount and adsorption rate of gas on the surface of a material in real time, and the measured data are closer to the real adsorption-desorption process, thereby providing more accurate data for engineering design. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application, the drawings involved in the embodiments will be briefly introduced as follows.

[0029] Figure 1 is a gas dynamic adsorption test device (sample injection mode) of the present application;

[0030] Figure 2 is a gas dynamic adsorption test device (purging mode) of the present application;

[0031] Figure 3 is a CO2 breakthrough curve of a mesoporous silica material modified with different proportions of polyethyleneimine tested by the gas dynamic adsorption test device of the present application;

[0032] Figure 4 is a CO2 breakthrough curve of a mesoporous silica material modified with 50wt.% polyethyleneimine at different adsorption temperatures;

[0033] In the figure, A: gas cylinder A, B: gas cylinder B, C: gas cylinder C, D: auxiliary gas cylinder, E: buffer tank, F: four-way valve, G: tubular resistance heating furnace, H: adsorption reaction column, I: thermal conductivity detector, J: data recorder, K1-K4: on-off valve. DETAILED DESCRIPTION

[0034] The present application will be described in detail below in combination with the embodiments, but the implementation of the present application is not limited thereto. Obviously, the embodiments described below are only some of the embodiments of the present application, and other similar embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0035] Example 1

[0036] A gas dynamic adsorption test device, comprising a cylinder containing different gases, a mass flow meter, an adsorption reaction column, a four-way valve, a tubular resistance heating furnace, a thermal conductivity detector, a data recorder and pipelines, valves and pressure gauges connected therebetween:

[0037] The gas cylinder, the on-off valve K, the mass flow meter and the pipeline connected between them constitute a gas supply unit, wherein the gas cylinder A, the gas cylinder B and the gas cylinder C (the number of gas cylinders can be adjusted according to actual use) are connected through the on-off valves (K1, K2, K3) and the mass flow controllers (MFC1, MFC2, MFC3) respectively, the flow is adjusted, and the sample gas is formed by uniform mixing in the buffer tank E; the gas cylinder D is divided into two paths through the on-off valve (K4), one path becomes the reference gas into the thermal conductivity detector (TCD) through the mass flow controller (MFC4), and the other path becomes the purge gas through the mass flow controller (MFC5); the sample gas path and the purge gas path are switched through the four-way valve (F) to enter the adsorption reaction column (H), Figure 1 is the sample gas mode, Figure 2 is the purge mode; the adsorbent to be tested is filled in the adsorption reaction column (H), the adsorption reaction column (H) has a fixed volume and is made of one of stainless steel and quartz glass, and the adsorbent is supported by quartz wool or a stainless steel sieve plate when filled in the adsorption reaction column H; the adsorption reaction column (H) is placed in the tubular resistance heating furnace (G) for temperature control, and the temperature control range of the tubular resistance heating furnace (G) is 30-500℃.

[0038] Example 2

[0039] The preparation method of the polyethyleneimine modified mesoporous silica material mainly includes the following steps:

[0040] (1) 10 g of Pluronic P123 is dissolved in 200 mL of 1.6M HCl aqueous solution at a temperature of 40℃, after complete dissolution, 13 g of mesitylene is added and stirred at 40℃ for 2 h, then 25 mL of tetraethyl orthosilicate is added dropwise to the solution, and then kept at a temperature of 40℃ for 20 h; 120 mg of NH4F is added, and aged in the reaction kettle at 140℃ for 24 h, the obtained precipitate is filtered and washed with deionized water and ethanol; finally, calcined at 700℃ in air for 7 h to obtain a foamed mesoporous silica material;

[0041] (2) A mixture of 5 g of the foamed mesoporous silica material obtained in step (1) and 10 g of (3-glycidyloxypropyl)triethoxysilane is dispersed in 20 mL of anhydrous toluene, heated to 120℃ under nitrogen protection for 6 hours of reflux, filtered and washed with anhydrous toluene and ethanol, and then the precipitate is dried at 100℃ for 5 hours;

[0042] (3) 2 g of polyethyleneimine is dissolved in 50 mL of a methanol / water mixture (the volume ratio of methanol to water is 1:1), 4 g of the epoxy-modified foamed mesoporous silica obtained in step (2) is added, and then the reaction is carried out at 80℃ for 6 h of reflux, and the obtained material is evaporated to obtain a polyethyleneimine modified mesoporous silica material.

[0043] Reference to the above preparation method to prepare different proportions (30%, 50%, 70%, 90%) of polyethyleneimine modified mesoporous silica material.

[0044] Example 3

[0045] The method for measuring the adsorption capacity of the polyethyleneimine modified mesoporous silica material prepared in Example 2 for CO2 using the gas dynamic adsorption test device of Example 1 includes the following steps:

[0046] (1) 1 g of adsorbent is packed in a quartz glass adsorption column H, and the upper and lower ends are supported with quartz wool;

[0047] (2) High-purity CO2 is adjusted to 5 mL / min by mass flow controller MCF1, high-purity N2 is adjusted to 20 mL / min by mass flow controller MCF2, and is uniformly mixed in buffer tank E to form a mixture of 20% vol. CO2 / 80% vol. N2; high-purity N2 is divided into two paths after passing through switch valve K4, one path is adjusted to 15 mL / min by mass flow controller MFC4 to become a reference gas entering the thermal conductivity detector TCD, and the other path is adjusted to 20 mL / min by mass flow controller MFC5 to become a purge gas;

[0048] (3) Adjust four-way valve F to the purge mode, and heat tube furnace G to 160°C and maintain for 1 h to remove the adsorbed gas from the device and the material;

[0049] (4) Reduce the temperature of tube furnace G to 50°C, switch four-way valve F to the sample injection mode, and measure and record the breakthrough curve signal by TCD and the recorder until the signal remains stable after breakthrough.

[0050] (5) The relationship between the TCD signal value and the gas concentration is obtained by external standard method, and the adsorption capacity of the sample for the adsorption gas is calculated by the following formula:

[0051]

[0052] Wherein, Q is the saturated adsorption capacity of unit mass of adsorbent for gas, mmol / g; Co is the mass concentration of inlet gas, %; Ci is the mass concentration of outlet gas after i minutes from the start of adsorption, %; F is the total flow rate of gas, mL / min; t b is the adsorption breakthrough time (C i / C0=5%), min; t s is the adsorption saturation time (C i / C0=100%), min; m is the amount of adsorbent loaded (the mass difference of the adsorbent before and after activation in the glass tube), g; T is the adsorption temperature (K); T0 is 273K, V m The value represents the molar volume of the gas under standard conditions (mL / mmol).

[0053] Example 4

[0054] The operation method in Example 3 is the same, except that in step (1), 1g of mesoporous silica material modified with different proportions (30%, 50%, 70%, 90%) of polyethyleneimine is loaded, and its breakthrough curve is as follows. Figure 3 As shown.

[0055] Example 5

[0056] The operation method in Example 3 is the same, except that in step (4), different adsorption temperatures (30, 40, 50, 60, 70, 80, 90, 100°C) are set to evaluate the performance of the mesoporous silica material modified with 50 wt.% polyethyleneimine. The breakthrough curve is shown in Figure 3. Figure 4 As shown.

[0057] In summary, this invention can measure the amount and rate of gas adsorption on the material surface in real time. The measured data is closer to the actual adsorption-desorption process, providing more accurate data for the engineering design process. Moreover, the testing device has a simple structure, is easy to operate, and has low manufacturing cost, and can be used in the laboratory to evaluate the performance of adsorbents.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas dynamic adsorption testing device, characterized in that, The gas dynamic adsorption testing device mainly includes n gas cylinders containing different gases, a mass flow controller, a buffer tank, an adsorption reaction column, a four-way valve, a tubular resistance heating furnace, a thermal conductivity detector, and a data logger. The outlets of the gas cylinders containing different gases are connected to the buffer tank via pipelines. Each gas cylinder's outlet pipeline is sequentially equipped with a switch valve and a mass flow controller. The outlet of the buffer tank is connected to the first port of the four-way valve via a pipeline. The second port of the four-way valve is connected to the inlet of the adsorption reaction column via a pipeline. The adsorbent to be tested is filled into the adsorption reaction column. The outlet of the adsorption reaction column is connected to the thermal conductivity detector via a pipeline. The thermal conductivity detector is connected to the data logger. The adsorption reaction column is placed in the tubular resistance heating furnace. An auxiliary gas cylinder is connected to the switch valve via a pipeline. The outlet of the switch valve branches into pipeline I and pipeline II. Pipeline I is connected to the mass flow controller. The outlet of the mass flow controller is connected to the reference gas inlet of the thermal conductivity detector. Pipeline II is connected to the fourth port of the four-way valve via the mass flow controller. The first and second ports of the four-way valve are connected to form the sample injection mode; The second and fourth ports of the four-way valve are connected to form a purging mode.

2. The gas dynamic adsorption testing device according to claim 1, characterized in that, A pressure gauge is installed at the outlet of each switching valve.

3. The gas dynamic adsorption testing device according to claim 1, characterized in that, n=2, the gas cylinders containing different gases are high-purity CO2 gas cylinders and high-purity N2 gas cylinders.

4. The gas dynamic adsorption testing device according to claim 1, characterized in that, When the adsorbent is packed into the adsorption reaction column, it is supported at the top and bottom by quartz wool or stainless steel sieve plates.

5. The gas dynamic adsorption testing device according to claim 1, characterized in that, The temperature control range of the tubular resistance heating furnace is 30~500℃.

6. The gas dynamic adsorption testing device according to claim 1, characterized in that, The adsorption reaction column has a fixed volume and is made of either stainless steel or quartz glass.

7. The test method of the gas dynamic adsorption test device according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Set the device to purge mode and heat it with a tubular resistance heating furnace to remove the gas adsorbed on the adsorption reaction column and the surface of the adsorbent. (2) Lower the tubular resistance heating furnace to the temperature to be measured and set the device to sample injection mode; (3) Record the gas breakthrough curve using a thermal conductivity detector and a data logger until the signal remains stable after the breakthrough. (4) The relationship between the thermal conductivity detector signal value and the gas concentration was obtained using the external standard method. The adsorption capacity Q of the adsorbent for the gas was then calculated using the following formula: In the formula, Q represents the saturated adsorption capacity of the adsorbent per unit mass of gas, in mmol / g; C0 represents the inlet gas concentration, in %; and Ci represents the outlet gas concentration after i minutes of adsorption, in % F represents the total gas flow rate, measured in mL / min; t b The adsorption breakthrough time is expressed in minutes (t). s , where m is the adsorption saturation time in minutes; m is the amount of adsorbent loaded, which is the mass difference of the adsorbent before and after activation in the glass tube, in grams. T is the adsorption temperature, in K; T0 is 273 K, V m This represents the molar volume of the gas under standard conditions, expressed in mL / mmol.

8. The test method according to claim 7, characterized in that, In step (1), the heating temperature should be 30-50°C lower than the decomposition temperature of the adsorbent, and the heating time should be more than 1 hour.

9. The test method according to claim 7, characterized in that, The purging gas used in step (1) is an inert gas, which is one or more of N2, He and Ar.

10. The test method according to claim 7, characterized in that, In step (2), the temperature to be measured is 30~100℃.

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