JP2003240743A - Apparatus for measuring adsorption energy of adsorbing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for easily measuring the adsorption energy of an adsorbing material. <P>SOLUTION: A sample cell 11 for accommodating an adsorbing material 14 and a vacuum apparatus are connected by a connecting hose 13. Three switchgears 17, 18, and 19 are provided in the connecting hose. A branch pipe 21 is provided in the connecting hose between the first switch gear 17 that is provided at a vacuum device 12 in the three switchgears 17, 18, and 19, and the vacuum device 12. An adsorption gas supply section 22 is provided at the end section. A pressure gauge 27 is provided between the third switch gear 19 that is provided at the side of the sample cell in the three switchgears 17, 18, and 19, and the second switchgear 18 that is provided between the first switchgear 17 and the third switchgear 19 in the three switchgears. Then, an amount-of-heat measuring means is provided to measure an change in the amount of heat in the sample cell 11. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an apparatus for measuring the adsorption energy of an adsorbent.

[0002]

2. Description of the Related Art The adsorption energy of an adsorbent such as zeolite or activated carbon is calculated from the amount of adsorption and the change in heat at that time. At this time, the adsorption energy of the adsorbent changes depending on the pressure of the atmosphere.

For this reason, it is necessary to calculate the adsorption energy while changing the pressure of the atmosphere. However, repeating the operation of setting and measuring the pressure is a serious task.

[0004] Therefore, an object of the present invention is to provide an apparatus for easily measuring the adsorption energy of an adsorbent.

[0005]

According to the present invention, a sample cell for accommodating an adsorbent and a vacuum device are connected by a connecting pipe, and the connecting pipe is provided with three opening / closing devices. A branch pipe is provided in a connecting pipe between the first switching device provided on the vacuum device side of the device and the vacuum device, and an adsorbed gas supply unit is provided at an end thereof, and a sample among the above three switching devices is provided. A third switching device provided on the cell side;
A calorimeter for measuring a change in calorific value of the sample cell by providing a pressure gauge in a connecting pipe between the first switchgear and the second switchgear provided between the first switchgear and the third switchgear of the three switchgears. The problem has been solved by using an adsorbent adsorption energy measuring device provided with means.

In the adsorption energy measuring device, first, an adsorbent is stored in a sample cell, the sample cell and the connection pipe are depressurized by a vacuum device, three opening and closing devices are closed, and the first opening and closing device is supplied by an adsorption gas supply unit. A predetermined pressure is applied to the adsorption gas supply section. Thereafter, the first switchgear is opened and then closed, the second switchgear is opened and then closed and the pressure is read from the pressure gauge, and then the third switchgear is opened and the pressure is read from the pressure gauge. At the same time, the calorie change in the sample cell is read from the calorie measuring means, and after the pressure and calorie change disappear, the third switchgear is closed, and then the first switchgear, the second switchgear and the third switchgear are opened. By repeatedly performing opening and closing, it is possible to measure the amount of adsorption and the change in the amount of heat under each pressure while changing the pressure, and from this, it is possible to calculate the adsorption energy of the adsorbent under each pressure.

Further, by automatically operating the first switching device, the second switching device, and the third switching device, and reading from the pressure gauge and the thermo module, the calculation of the adsorption energy of the adsorbent can be performed by the operator. You can get it without any hassle.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As shown in FIG. 1, a device for measuring the adsorption energy of an adsorbent according to the present invention includes a sample cell 1
1, a vacuum device 12, and a connecting pipe 13 connecting the sample cell 11 and the vacuum device 12.

The sample cell 11 is a cell for storing the adsorbent 14 and is connected to the connecting pipe 13. The sample cell 11 is installed in a calorie measuring unit, and the calorific value of the adsorbent 14 is measured by measuring a change in calorific value in the sample cell with the calorimetric unit.

As the calorie measuring means, an isothermal calorimeter,
Any means such as various calorimeters such as a heat flux calorimeter can be used.

As a specific example of the calorie measuring means, there is a calorie measuring means shown in FIG. 1 which includes a thermostat 23, a heat sink 24, a thermo module 15a and a thermo module 15b. This is because the sample cell 11 and the reference cell 16 are kept at a constant temperature during the measurement, and the heat transfer (heat flow rate) from the sample cell 11 and the reference cell 16 to the heat sink 24 is performed by each operation described later.
Detected by the thermo modules 15a and 15b,
It is to be calculated. The thermo module 15a electrically detects heat transfer from the sample cell 11 to the heat sink 24, and the thermo module 15b electrically detects heat transfer from the reference cell 16 to the heat sink 24. Thermo module 15
a, 15b, the adsorbent 14 in the sample cell 11
Can be measured.

It is desirable that the thermostatic chamber 23 can maintain a constant temperature for a long time, and the heat sink 24 is generated inside the sample cell 11 and the reference cell 16.
The heat transmitted through the thermo modules 15a and 15b is quickly diffused, and serves to keep the temperature around the sample cell 11 and the reference cell 16 constant. For these reasons, it is desirable that the heat sink 24 be made of aluminum or the like having good heat conductivity.

The adsorbent 14 is an object for obtaining adsorption energy, and any adsorbent such as zeolite and activated carbon can be used.

The connecting pipe 13 has three opening / closing devices 1
7, 18, and 19 are provided in series. Of the three switching devices, the switching device provided on the vacuum device 12 side is the first switching device.
The switchgear provided on the sample cell 11 side is referred to as a third switchgear 19, and the switchgear provided between the first switchgear 17 and the third switchgear 19 is referred to as a second switchgear. It will be referred to as a switchgear 18. The types of the first to third opening / closing devices 17 to 19 are not particularly limited as long as the operations described below can be performed. Examples include valves and the like.

A branch pipe 21 is provided in the connecting pipe 13 between the first opening / closing device 17 and the vacuum device 12, and an adsorbing gas supply unit 22 is connected to an end of the connecting pipe 13 through an adsorbing gas opening / closing device 25.
Is provided. The adsorbing gas supply unit 22 is for supplying a gaseous substance of the adsorbed substance adsorbed by the adsorbent 14.

As shown in FIG. 1, a pressure gauge 27 is provided in the connecting pipe 13 between the second switching device 18 and the third switching device 19. Thereby, the pressure change can be read.

Further, a pressure adjusting cell 26 may be provided in the connecting pipe 13 between the second switching device 18 and the third switching device 19 as needed. This is because, when introducing the adsorption gas into the sample cell 11 by a method described later, if the amount of the introduced gas is too small, the number of measurement points becomes enormous, and a long measurement time is required. The amount of heat and the amount of adsorption may be reduced, and measurement accuracy may be reduced. In such a case, it is used to adjust the introduced gas amount to an appropriate value. In FIG. 1, two pressure adjusting cells 26 are provided, but this number may be 0 depending on the amount of the adsorbent to be measured, the size of the adsorption energy measuring device, the size of the pressure adjusting cell 26 itself, and the like. Well one
Or a plurality of two or more.

Next, a method for measuring the adsorption energy of an adsorbent using the adsorption energy measuring apparatus according to the present invention will be described.
This will be described using the adsorption energy measuring device shown in FIG.

As a preparation before measurement, a predetermined amount of adsorbent 14
The calibration heater 28 is attached to the sample cell 11 in which is stored, and is heated. Then, the voltage change sensed by the thermo modules 15a and 15b at that time is measured. Then, an integral value (Va-Vb) from the start to the end of the voltage change generated by applying heat is calculated, and the calibration factor (F) is calculated from these values and the added heat amount by the following equation (1). ). Q = F (Va−Vb) (1) In the above equation (1), Q is the total amount of heat added, Va is an integrated value of a voltage change detected by the thermo module 15a, and Vb is detected by the thermo module 15b. The integral value of the voltage change, F indicates a calibration factor. This calibration factor is used to calculate the amount of change in calorific value due to the adsorbent from the measured values of Va and Vb in the measurement described later.

Next, a measuring method will be described. This measurement is composed of two kinds of operations, an initial operation and an opening and closing operation of the opening and closing device. First, the initial operation will be described. First, an adsorbent to be measured is stored in the sample cell 11 to form a sample cell portion including the sample cell 11, the reference cell 16, and the sample cell communication opening / closing device 20.

Next, as shown in FIG.
This sample cell portion (portion surrounded by a broken line in FIG. 2) is installed in a pretreatment constant temperature bath 31 to form a pretreatment portion. Further, the sample cell communication opening / closing device 20 is connected to the pretreatment open end 30 (FIG. 1).

Then, the first switching device 17 and the adsorption gas switching device 25 are closed, and the sample cell communication switching device 2 is closed.
0, and the opening / closing device 29 for pretreatment is opened, and the vacuum device 12
To reduce the pressure, raise the temperature of the pretreatment constant temperature bath 31, and perform the pretreatment at the target temperature. The pretreatment time and temperature at this time differ depending on the purpose. In addition, it is preferable to open the pretreatment opening / closing device 29 little by little in order to prevent scattering of the adsorbent in the sample cell 11 due to reduced pressure. By this pretreatment, it is possible to remove attached substances and the like on the surface of the adsorbent 14.

After the pretreatment, the sample cell connecting switchgear 2
0 is closed, and the sample cell part is removed from the pretreatment constant temperature bath 31 and placed inside the heat sink 24 in the constant temperature bath 23 of the calorimetric measurement unit which has been adjusted to a constant temperature in advance.
Then, after closing the opening / closing device 29 for pretreatment, the first opening / closing device 17, the second opening / closing device 18, and the third opening / closing device 19 are opened, and the inside of the connecting pipe 13 is depressurized by the vacuum device 12. Next, the sample cell communication switchgear 20 is opened, and the inside of the sample cell 11 and the inside of the reference cell 16 are reduced in pressure.

Then, the temperatures of the sample cell 11 and the reference cell 16 become the same as those of the calorie measuring section, and the thermo modules 15a, 15 attached in the calorie measuring section.
After the change in the heat flow rate detected from 5b has ceased, the first
-The entrances of the third opening / closing devices 17, 18, 19 and the vacuum device 12 are closed. Next, the adsorption gas supply unit 22 is opened, and the adsorption gas is supplied to the connecting pipe 13 and the branch pipe 21 extending from the adsorption gas supply unit 22 to the first opening / closing device to apply a predetermined pressure. At this time, when the feed-containing gas is in a condensed liquid state, the connecting pipe 13 and the branch pipe 2 at that time are used.
The pressure in 1 is the saturated vapor pressure of the adsorbed gas at that temperature. The predetermined pressure is set to a third opening / closing device 1 described later.
In opening 9, there is no particular limitation as long as the pressure change applied inside sample cell 11 is not too large. This is because if the pressure change applied to the sample cell 11 is too large, it is impossible to obtain data at fine pressure increments. The following operation is performed while the adsorption gas supply unit is kept open.

Next, the opening and closing operation of the above opening and closing device will be described. First, the first opening / closing device 17 is opened and then closed. Thereby, pressure is applied to the communication pipe 13 between the first switching device 17 and the second switching device 18 as compared with the initial state. Then, the second opening / closing device is opened and then closed. Thereby, the second switching device 18 and the third switching device 1
9, that is, pressure is applied to the area VG shown in FIG. 1 as compared with the initial state. At this time, the pressure is read by the pressure gauge 27.

When the pressure gauge 27 does not show a value equal to or higher than a predetermined pressure when the second switch 18 is opened, the second
After closing the opening and closing device 18, the first opening and closing device 17
Repeat the operation from opening and closing. That is, the second switchgear 1
After closing 8, the first opening / closing device 17 is opened and then closed. Then, the second opening / closing device is opened and then closed. In this way, the pressure of the communication pipe 13 between the second switching device 18 and the third switching device 19 is set to a value equal to or higher than a predetermined pressure.

The predetermined pressure is the amount of change in pressure applied between the third switching device 19 and the sample cell 11 when the third switching device 19 is opened in the next step, that is, the pressure applied to the area VC in FIG. Is enough pressure. If the change in pressure applied to the sample cell 11 is too small, the adsorbent 1
This is because sufficient adsorption of the adsorbed substance to No. 4 does not occur, and data may not be obtained. The predetermined pressure varies depending on the adsorption behavior of the adsorbent 14, the purpose of measurement, and the sample amount. This predetermined pressure is set according to the amount of the adsorbed gas to be introduced. For example, when the amount of the adsorbent 14 is small or when it is desired to measure a small pressure change, the predetermined pressure is set to be small.

When it is desired to adjust the amount of the adsorbed gas to be larger, the pressure adjusting cell 26 may be used. When the amount of the adsorbent 14 is large, the volume of the connecting pipe 13 between the second opening / closing device 18 and the third opening / closing device 19 is small, and even if the set pressure is increased, the amount of gas introduced becomes small. At this time, if the pressure adjustment cell 26 is used, the volume of the space between the second switching device 18 and the third switching device 19 can be increased, and a large amount of gas can be introduced at one time.

Next, the third switching device is opened. Then
The adsorption gas is introduced into the sample cell 11 and the adsorbent 14
The adsorbate gas is adsorbed on the substrate, and an adsorption equilibrium state at the equilibrium pressure occurs. The equilibrium pressure at this time is read from the pressure gauge 27. In addition, a change in the amount of heat from the time immediately after the introduction of the adsorption gas until the adsorption equilibrium is reached (the difference between the integrated values of the heat velocities detected by the thermo modules 15a and 15b) is measured and calculated. After reaching equilibrium, the third switching device is closed. In determining the equilibrium state, a point in time at which the pressure decrease due to the adsorption and the change in the heat flow rate due to the adsorption have disappeared is regarded as the equilibrium state.

In this case, the adsorbed gas between the first opening / closing device 17 and the second opening / closing device 18 spreads over the area VC and the area VG. The degree of occurrence is small.

Next, the opening / closing operation of the opening / closing device, that is, the opening / closing operation of the first opening / closing device 17, the second opening / closing device 18 and the third opening / closing device 19 is repeatedly performed. Thus, the pressure can be gradually increased, and a change in the amount of heat in the sample cell 11 under the pressure can be obtained.

The adsorbed amount of the adsorbent 14 is obtained from the pressure before opening the third switching device 19 and the pressure after equilibrating after opening the third switching device 19 using the following equation (2). The obtained adsorption amount and the sample cell 1
The adsorption energy can be calculated from the change in the amount of heat within 1. ν _n = [P _{in, n} × V _g + P _{eq, n-1} × V _c −P _eq , _n × (V _g + V _c )] / RT (2) where n is the number of measurement repetitions and v _n is The adsorption amount in the n-th measurement, V _g is the internal volume of the area VG, V _c is the internal volume of the area VC, and Pin _{, n} is the introduction pressure (that is, the third opening / closing device 19 is opened in the n-th measurement). The pressure in the immediately preceding area VG), P _{eq, n} is the third in the n-th measurement.
The opening / closing device 19 is opened, the equilibrium pressure when the adsorption equilibrium is reached, R is the gas constant, and T is the temperature.

In the adsorption energy measuring apparatus according to the present invention, it is preferable that at least the sample cell 11 and the reference cell 16 in the area VC are thermostated in the thermostat 23. In addition, it is preferable that portions other than the vacuum device 12 that are the portion of the area VG and the portion other than the area VG and the area VC are also disposed in a constant temperature system at a constant temperature. At this time, the temperature of this part is the area V
The temperature is preferably about the same as the temperature of area C. In particular, when the adsorbed gas is a condensed liquid, the temperature is preferably about 5 to 10 ° C. higher than the area VC. This is because the connecting pipe 13 and the branch pipe 21
This is to prevent condensation from occurring in the interior. Thereby, the value of T in the above equation (2) can be treated as a constant value.

The determination of V _g and V _c is performed under the same conditions as the temperature at the time of measurement. The number of repetitions of the above measurement is not particularly limited, but it is preferable to perform the measurement more than 10 times, because finer data of adsorption energy under each pressure can be obtained.

The first switching device 17 and the second switching device 1 described above.
8 and the operation of the third switching device 19 and the pressure gauge 2
Reading of 7 may be performed manually, but is preferably performed automatically by an automatic control device such as a computer. This is because, as described above, since many repetitive operations are performed, the labor of the operator can be saved, and the accuracy of the operation can be maintained.

It is to be noted that the operations of the first opening / closing device 17, the second opening / closing device 18 and the third opening / closing device 19, the operation of the pressure gauge 27 and the thermo module 15 are automated.
The operation is not limited to the reading from the a and 15b, but the operation prior to them, such as the decompression operation of the inside of the sample cell 11 and the connection pipe 13 by the vacuum device 12 and the connection pipe 13 from the first opening and closing device to the adsorption gas supply unit 22 The operation of supplying the adsorbed gas to the branch pipe 21 and the like may be automated.

[0037]

According to the present invention, since the pressure applied to the area VC can be gradually increased, it is possible to obtain the adsorbing energy of the adsorbent under each pressure by a series of measurements in small increments of pressure. It is a target.

Further, since the third switching device is controlled based on data including not only the pressure gauge but also the calorimeter, more efficient and accurate measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an adsorption energy measuring device according to the present invention.

FIG. 2 is a schematic diagram showing an example of a preprocessing unit connected to the preprocessing open end 30 in FIG. 1;

[Explanation of symbols]

11 sample cells 12 Vacuum equipment 13 Connecting pipe 14 Adsorbent 15a, 15b Thermo module 16 Reference Cell 17 First switchgear 18 Second switchgear 19 Third switchgear 20 Switchgear for sample cell communication 21 Branch pipe 22 Adsorption gas supply section 23 constant temperature bath 24 heat sink 25 Adsorption gas switching device 26 Pressure adjustment cell 27 Pressure gauge 28 Calibration heater 29 Switchgear for pretreatment 30 Open end for pretreatment 31 Pretreatment thermostat

Claims (4)

[Claims] 1. A sample cell for accommodating an adsorbent and a vacuum device are connected by a connecting pipe, and the connecting pipe is provided with three opening / closing devices, and is provided on the vacuum device side among the three opening / closing devices. A branch pipe is provided in a connecting pipe between the first opening / closing device and the vacuum device, and an adsorbing gas supply unit is provided at an end thereof. A pressure gauge is provided in a connecting pipe between the switchgear and a second switchgear provided between the first switchgear and the third switchgear among the three switchgears, and the calorie change of the sample cell is provided. An adsorbent adsorption energy measuring apparatus provided with a calorimetric measuring means for measuring the adsorbent. 2. The sample cell contains the adsorbent, the vacuum device decompresses the sample cell and the connecting pipe, closes the three opening / closing devices, and the first opening / closing device by the adsorption gas supply unit. After applying a predetermined pressure to the adsorption gas supply unit from above, the first switching device is opened and then closed, and the second switching device is opened and then closed to read the pressure from the pressure gauge. The third switchgear is opened to read the pressure from the pressure gauge, and at the same time, the calorimetric change in the sample cell is read from the calorie measuring means. After the pressure and calorie change disappear, the third switchgear is closed. The adsorption energy of the adsorbent according to claim 1, wherein the adsorption energy of the adsorbent is measured by repeatedly opening and closing the first switching device, the second switching device, and the third switching device. Constant apparatus. 3. When the second switchgear is closed after being opened, if the pressure gauge does not indicate a value equal to or higher than a predetermined pressure, the second switchgear is closed and the first switchgear is closed. The apparatus for measuring the adsorption energy of an adsorbent according to claim 2, wherein the operation is repeated from the opening and closing. 4. The operation of the first switchgear, the second switchgear and the third switchgear, and the reading from the pressure gauge and the thermo module are automatically performed.
The adsorption energy measuring device for an adsorbent according to any one of the above.