JPH08201266A - Pore distribution measuring instrument and constant-quantity injector - Google Patents

Abstract

PURPOSE: To provide a measuring method by which measuring time can be shortened and measurement errors are not accumulated. CONSTITUTION: A pore distribution measuring instrument is provided with a system which is provided so that gases introduced to a thermostatic chamber 35 from an adsorbed gas source 1 and non-adsorbed gas source 2 can be switched to each other by means of stops valves 10 and 11 after the pressure of the gases are adjusted to a constant pressure by means of precision regulators 8 and 9 and injects the gases into the upper piping of a sample cell 20 by means of a constant-quantity injector 19, second system in which a plurality of stop valves and volume pipes 18 are provided in the piping connecting the upper piping of the cell 20 to a vacuum pump 28, and third system in which a stop valve is provided in the upper piping of a reference cell 21 removably provided on the outside of the chamber 35 so that the gases and pump 28 can be switched to each other. The measuring instrument is also provided with pressure tranducers 24, 25, and 26 provided in the upper piping of the cell 20 and that of the cell 21, a vacuum gauge provided in the piping led to the pump 28, control means 32 which controls the valves 10 and 11 and injector 19 and detects pressure signals, arithmetic means 33 which performs monitoring control and data analysis, and output means 34 which outputs results.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pore distribution measuring apparatus for adsorbing a gas on a solid sample and measuring the distribution of the physical properties of the solid by varying the adsorption amount.

[0002]

2. Description of the Related Art Conventionally, as a pore distribution measuring device used for measuring equilibrium pressure during adsorption, Japanese Patent Publication No. 53-31
5 Adsorption / desorption amount automatic measuring device, Japanese Patent Publication No. 5-19096 Adsorption method using fully automatic adsorption device, Japanese Patent Publication No. 5-394
27 sample analysis method and device, Japanese Patent Publication No. 6-23676
A method known as a constant volume method or a constant volume method, which has been known for a long time based on a principle used for an adsorption amount measuring device, and two types called a constant flow method using a mass flow meter according to Japanese Patent Publication No. 4-5341. The method is known.

According to the measuring method by the constant flow rate method described in Japanese Patent Publication No. 4-5341, the adsorbed gas flow rate is stabilized by a mass flow controller having a mass flow meter, and the adsorbed gas is continuously flown into the sample cell for measurement. There is a purpose to do. Therefore, according to the conventional technique described in the publication, since the adsorption pressure is measured at the non-equilibrium pressure, there is a problem that the reliability of the adsorption result is poor. Further, there is also a problem that the manufacturing cost rises because an expensive mass flow controller and control signal system are provided.

Japanese Patent Publication No. 53-315, Automatic adsorption / desorption amount measuring device, Japanese Patent Publication No. 5-19096 Adsorption method using fully automatic adsorption device, Japanese Patent Publication No. 5-39427, Sample analysis method and device, Japanese Patent Publication No. 6- The measurement method by the constant volume method described in the 23676 adsorption amount measuring device will be described with reference to FIG. 5 showing the operation of the conventional technique. Adsorption of a predetermined pressure to a volume chamber (volume Vs) partitioned by a sample cell (volume Vd) and an on-off valve. The purpose is to measure the equilibrium pressure of the sample cell and the volume chamber (volume Vd + Vs) after opening the on-off valve after filling and sealing the gas.

Therefore, when the adsorption amount Vn is obtained by the constant volume method described in the publication, iterative calculation represented by the following formula 1 is required.

[0006]

[Equation 1]

According to this, since the previous adsorption amount Vn-1 is added every time, even a numerical value including a measurement error is added, and there is a problem of cumulative error that greatly affects the measurement accuracy.

Further, in the construction of the measuring device by the volume method, since the volume chamber Vs is used as a constant temperature chamber and the sample cell is arranged in the Dewar bottle, the temperature in the volume chamber is about 30 to 40 degrees higher than the room temperature, which is usually higher than room temperature. After communicating with an environment of extremely low temperature such as liquid nitrogen, store at the equilibrium pressure and measure. According to this, first, it is necessary to provide a stable time for the adsorbed gas introduced into the volume chamber Vs to expand until the temperature of the thermostatic chamber is reached, and further the adsorption equilibrium is reached after the communication with the sample cell Vd by the on-off valve. Must be stored until. The reason is that if the internal pressure of the sample cell was still changing after closing the on-off valve to start the next adsorption measurement, not only an accurate adsorption amount could not be obtained, but also the measurement error as described above. This is because they are accumulated and become extremely unreliable. Further, in the physical adsorption phenomenon such as nitrogen gas adsorption, although the adsorption phenomenon occurs almost instantaneously, it takes a lot of time to reach adsorption equilibrium in the volumetric method. The main members are the volume chamber Vs and the sample cell Vd. The main factors are distance, volume, and temperature difference. Therefore, the volumetric method of the prior art has a problem that it takes a long time for measurement.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a measurement method for performing measurement by perfect adsorption equilibrium and shortening the time required for adsorption equilibrium, and not accumulating measurement errors. The purpose is to propose.

[0010]

According to the first aspect of the present invention, a thermostatic chamber in which the temperature inside the tank is controlled to a predetermined temperature is provided, and a constant temperature is maintained from the adsorption gas source and the non-adsorption gas source provided outside the thermostatic chamber. The gas introduced into the chamber is regulated to a constant pressure by a precision regulator and can be switched by an on-off valve, and the adsorbed gas or non-adsorbed gas is injected into the upper pipe of the sample cell detachably installed outside the temperature-controlled room by a fixed quantity injector. Have a system to do. Further, it has a system in which a pipe leading from the sample cell upper pipe to a vacuum pump provided outside the temperature-controlled room is provided with a plurality of open / close valves and a volume pipe provided between the open / close valves. Furthermore, the system has a system in which a plurality of open / close valves are provided in an upper pipe of a reference cell detachably provided outside the thermostatic chamber so that the adsorption gas or the non-adsorption gas and the vacuum pump can be switched. Further, a pressure transducer is provided in each of the sample cell upper pipe and the reference cell upper pipe, a vacuum gauge is provided in the pipe guided to the vacuum pump, and control means for controlling the on-off valve and the quantitative injector and detecting a pressure signal. It is an apparatus for measuring pore size distribution, which comprises an arithmetic means for monitoring and controlling the control means and data analysis and an output means for outputting the analysis and control results.

According to the second aspect of the present invention, a diaphragm is provided so as to be closely arranged so as to cover the surface of the injector head in which one of the gas inlet and the gas outlet penetrating the injector head in parallel is open, and the diaphragm is entirely formed. The circumference is tightly fixed to the injector head by a fixing ring, and a diaphragm lot is provided at the center. Further, an inlet valve lot for pressing and closing the gas inlet from the outer surface of the diaphragm and an outlet valve lot for pressing and closing the gas outlet from the outer surface of the diaphragm are provided, and an actuator for driving the inlet valve lot, the diaphragm lot and the outlet valve lot, respectively. The metered dose injector for use in the invention of claim 1, further comprising:

[0012]

According to the first aspect of the present invention, a temperature-controlled room in which the temperature inside the tank is controlled to a predetermined temperature is provided, and the gas introduced into the temperature-controlled room from the adsorbed gas source and the non-adsorbed gas source provided outside the temperature-controlled room is supplied. The system has a system that injects a fixed amount of pressure into the upper pipe of the sample cell by means of a fixed-quantity injector, which is regulated to a constant pressure by a precision regulator and can be switched by an on-off valve. According to this, the sample cell and the upper pipe are a single container of an extremely low volume, which communicates with each other with substantially the same inner diameter. Standard state (P = 760To
In this configuration, the adsorption gas is quantitatively injected by a constant quantity injector whose injection quantity is known at rr, T = 273 ° K). Since the amount of gas injected by the constant-quantity injector at one time is extremely small, it is possible to measure with high resolution. Furthermore, adsorption occurs instantly and the time to reach equilibrium pressure in a low-volume sample cell is short. It is a pore distribution measuring device.

The metered dose injector according to the second aspect of the present invention is provided in a thermostatic chamber in which the temperature inside the tank is controlled to a predetermined temperature, and a gas regulated to a constant pressure by a precision regulator is introduced to the gas inlet. The introduced gas is sequentially driven by an actuator using a solenoid or an air cylinder as shown in FIG. 3 showing the operation of the present invention, 1: inlet valve opening, 2: gas suction, 3: air tightness, 4: outlet valve opening. 5, gas injection, 6:
The operation of closing is repeated and gas is injected into the sample cell. The gas collected by the airtightness of 3 is always a constant amount due to the environment where the temperature and pressure are precisely adjusted,
The inside of the sample cell to be injected has a function of being rapidly injected because of a pressure lower than the injection pressure (precision regulator setting pressure).

According to the invention of the present application described above, it is possible to carry out the measurement by a complete adsorption equilibrium and to shorten the measurement time.

[0015]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 shows an embodiment of the invention according to claim 1, according to which an adsorbed gas source provided outside the thermostatic chamber is provided with a thermostatic chamber (35) whose internal temperature is controlled to a predetermined temperature. The gas introduced from (1) and the non-adsorbed gas source (2) to the temperature-controlled room is regulated to a constant pressure by the precision regulators (8) and (9), and the switching valves (10) and (11) are provided so as to be switchable. The adsorbed gas (1) or the non-adsorbed gas (2) is attached to the upper pipe of the sample cell (20) detachably attached to
Has a system for injecting the sucrose with a metered dose injector (19). Furthermore, the volume provided between the plurality of on-off valves (15) (16) (17) and the on-off valves in the pipe leading from the upper pipe of the sample cell (20) to the vacuum pump (28) provided outside the temperature-controlled room. It has a system provided with a pipe (18). Further, a plurality of on-off valves () that can switch between the adsorbed gas (1) or the non-adsorbed gas (2) and the vacuum pump (28) are provided in an upper pipe of a reference cell (21) detachably provided outside the temperature-controlled room. 12) (13) (14) is provided. Further, pressure transducers (24) and (25) are respectively provided in the sample cell upper pipe and the reference cell upper pipe.
And a vacuum gauge (2
6) is provided, and the control means (32) for controlling the on-off valve and the fixed quantity injector (19) and for detecting the pressure signal, the arithmetic means (33) for monitoring and controlling the control means and the analysis and control results are displayed. The pore distribution measuring apparatus is characterized by comprising an output means (34) for outputting.

Further, in the embodiment, the gas or air introduced from the driving gas source (3) for driving the on-off valve is conditioned by the regulator (6), and the electromagnetic valve unit (7) driven by the control means is used. Has a system for driving the on-off valve. It also has a vertical unit (29) for vertically moving a constant temperature container (23) such as a Dewar bottle for adjusting the cells (20) (21) to an adsorption temperature. The vertical unit (29) of the embodiment is configured to realize vertical movement by the feed screw (31) and the forward / reverse rotation motor (30). Furthermore, regulators (4) and (5) provided when there are pressure fluctuations of the adsorbed gas source (1) and the non-adsorbed gas source (2) that cause error in the precision regulators (8) and (9), and HK
A vacuum booster pump (27) such as an oil diffusion pump or a turbo molecular pump, which is provided when a high vacuum is required for accurate analysis of micropores by the method, is also described.
The adsorption amount measuring device does not include the mantle heater and its temperature control system and the temperature control system of the temperature-controlled room, which are always used in the vacuum degassing in the pretreatment.

FIG. 4 shows another embodiment of the present invention, in which precision regulators (8) and (9) for adjusting the pressures of the adsorbed gas source (1) and the non-adsorbed gas source (2) are common. It is an application example of the pore size distribution measuring apparatus according to claim 1 of the present invention, which is configured by omitting one of the on-off valve (13) and the on-off valve (17).

FIG. 2 shows an embodiment of the invention as claimed in claim 2, according to which one of the gas inlet (53) and the gas outlet (54) passing through the injector head (51) in parallel. A diaphragm (52) which is closely arranged so as to cover the plane of the opened injector head is provided, and the entire circumference of the diaphragm is closely fixed to the injector head by a fixing ring (67), and a diaphragm lot (56) is provided at the central portion. It is provided.
A gas introduction pipe (61) led from the adsorbed gas source (1) or the non-adsorbed gas source (2) to the other of the gas inlets (53).
A gas injection pipe (62), which is communicated with the insertion joint (65) and is guided to the upper pipe of the sample cell (20), is connected to the other end of the gas outlet (54).
It is communicated by 6). Furthermore, the gas inlet (5
3) An inlet valve lot (55) for pressing and closing one side from the outer surface of the diaphragm (52) and the gas outlet (54)
An outlet valve lot (57) for pressing and closing one side from the outer surface of the diaphragm (52) is provided, and actuators (58) (59) (60) for driving the inlet valve lot, the diaphragm lot and the outlet valve lot are provided. The metered dose injector for use in the invention according to claim 1, wherein Further, in the embodiment, the diaphragm (5) is provided at the tip of the inlet valve lot (55) and the tip of the outlet valve lot (57).
A buffer member (63) is provided so as not to damage 2), and a connecting member (64) is provided at the center of the diaphragm (52) so that the diaphragm lot (56) can be attached and detached. In addition, a set screw or an actuator (58) (59) (6) for fixing the fixing ring (67) detachably.
The configuration of the drive system of 0) is omitted.

To use the pore distribution measuring apparatus of the present invention described above, the sample cell (20) charged with the sample (22) is mounted, and the opening / closing valves (15) (16) are opened and closed as necessary. The valve (17) is alternately opened and closed, the inside of the sample cell (20) is evacuated while being careful not to suck the sample (22), and further the heating vacuum deaeration is sufficiently performed by the mantle heater.

Next, a reference cell (21) which can be replaced by an empty sample cell is attached, and the on-off valves (13) (1) are attached.
4) Open (17) and evacuate. Here, the constant temperature container (23) is filled with the refrigerant corresponding to the adsorbed gas. The refrigerant can be applied to various adsorbed gases by using liquid nitrogen for nitrogen gas adsorption and liquid argon for argon gas adsorption.

Next, all the on-off valves are closed and the constant temperature container (23)
Is slowly raised by the vertical unit (29) to immerse the sample cell (20) and the reference cell (21) in the refrigerant. Here, the on-off valve (10) (1
2) Open (14) and set the adsorbed gas to the reference cell (2
It is introduced into 1) for about 3 to 5 minutes to generate a liquefied gas inside the reference cell (21) to open / close the valve (14).
To close and seal. The pressure transducer (25) provides an accurate saturated vapor pressure Ps of the adsorbed gas throughout the subsequent measurement inside the sealed vessel.

Next, the open / close valve (12), the open / close valve (13) and the open / close valve (17) are opened from the state where all the open / close valves are closed to purge the gas in the pipe and close all the open / close valves. Here, the on-off valve (11) is opened, a non-adsorbed gas represented by helium gas is introduced, and the sample cell (2
Gas is quantitatively injected into 0), and after a predetermined time, measurement is performed by the pressure transducer (24). This operation is performed at least ten times and the slope of the pressure rise is obtained by the least square method. This metrology data provides the apparent or dead volume value at the refrigerant temperature of the authentic sample cell (20) with the sample volume also subtracted.

Next, the open / close valves (15) and (16) and the open / close valve (17) are alternately opened and closed repeatedly as necessary, taking care not to suck the sample (22), and the non-adsorbed gas inside the sample cell (20). After performing sufficient purging of the on-off valves (12) (13)
Open (17) to purge residual gas in the pipe and close all on-off valves. Here, the on-off valve (10) is opened to introduce the adsorbed gas, the gas is quantitatively injected into the sample cell (20) by the fixed quantity injector (19), and after the time when the adsorption equilibrium is reached, the pressure transducer (24) is used. By measuring, adsorption isotherm data can be obtained. At this time, a fixed quantity injector (19)
If you measure each injection once, you can get the analysis result with high number of measurement points and high resolution accuracy, and if you measure after multiple injections, it will be a simple measurement in a short time, and the resolution and measurement time according to your purpose. Has the function to obtain. In order to use the pore size distribution measuring apparatus of the present invention most effectively, the calculation mode (3
It is desirable to register in 3) and use the appropriate flight properly.

For example, in order to obtain the measurement data of the micropore analysis by the HK method, the adsorption equilibrium pressure is measured for each injection to obtain the maximum resolution, and the BET is measured.
For the analysis of the specific surface area by the method, it is sufficient to have a resolution of several points up to a relative pressure of 0.35, so that it is sufficient to measure every tens of times. Furthermore, in order to obtain a resolution of at least 20 points or more for obtaining analysis data of macropore distribution from mesopores by the BJH method or DH method, it is possible to obtain sufficient resolution even if the measurement is performed several times to several tens of times.

Next, in order to obtain the desorption isotherm data according to the embodiment described in the present application, it is started near the saturated vapor pressure at the end of the adsorption measurement. In this case, the on-off valves (15) (17) are opened, the inside of the volume tube (18) is evacuated in advance, and then the on-off valves (15) (17) are closed. Here, the on-off valve (16) is opened and the pressure is measured after storage until the inside of the sample cell (20) is in adsorption equilibrium. The amount of desorption gas in this case is calculated according to the mathematical formula 1 by the constant volume method.

Conventionally, the desorption isotherm was generally used for the pore distribution analysis by the BJH method or the DH method. However, according to the literature (Yoshio Morioka, Surface, Vol 28, 598/1990), As shown in "Pore size distribution and pore network structure", it is clear that the adsorption measurement method according to the present invention is useful because the analysis by the adsorption isotherm is suitable for the analysis of the pore distribution. Is. Therefore, the desorption measurement according to the present invention is limited to the case where it is used for the analysis of the hysteresis characteristic of the adsorption / desorption isotherm due to the pot-shaped pores, but according to the examples of the present invention, the measurement by the complete adsorption equilibrium is possible. .

The pore size distribution measuring apparatus according to the present invention can be particularly noted in that a highly precise and flexible measurement pattern can be selected in the adsorption measurement. Further, the adsorption gas amount Vn can be obtained by the adsorption measurement method described in the present invention as follows. It can be obtained very easily as in the formula 2.

[0029]

[Equation 2]

According to this, when the adsorption amount at an arbitrary relative pressure is obtained, it can be instantly obtained without performing a complicated repetitive calculation such as Equation 1. In addition, there are few measurement errors due to the measurement method, and highly accurate measurement is possible due to the synergistic effect that does not cause cumulative errors due to adsorption calculation.

[0031]

According to the present invention which has been described in detail, the following effects are obtained by the above-mentioned configuration.

Since the adsorption measuring method of the present invention is a method of measuring the complete adsorption equilibrium pressure instead of measuring while flowing the adsorption gas, the measured value is highly reliable. Further, since an expensive mass flow controller and control signal system are unnecessary, the manufacturing cost is low.

Since the communication operation with the volume chamber Vs is not required unlike the constant volume method, only the sample cell volume Vd becomes a small volume, and the arrival time of the adsorption equilibrium pressure is shortened, and the skip operation for executing the quantitative injection device a plurality of times is performed. A flexible measurement pattern that does not generate an error even when performing is possible. Similarly, the measurement accuracy is high because it is an absolute pressure measurement method that measures only the adsorption equilibrium pressure, not the measurement by differential pressure measurement. Similarly, a higher measurement accuracy can be obtained by a measurement method that does not cause a cumulative error in the adsorption amount calculation.

Further, as shown in the embodiment of the present invention, both the on-off valve driving method and the metering device driving method are ON-O.
Since the FF control is used, there is no effect that an analog control signal such as a mass flow controller or a leak valve is not required and the device can be manufactured at a low cost.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an embodiment of claim 1 of the present invention.

FIG. 2 is a sectional view showing an embodiment of claim 2 of the present invention.

FIG. 3 is a cross-sectional view showing the operation of claim 2 of the present invention.

FIG. 4 is a device configuration diagram showing another example of the embodiment of claim 1 of the present invention.

FIG. 5 is a device configuration diagram showing an operation of a conventional technique.

[Explanation of symbols]

 1 Adsorbed gas source 2 Non-adsorbed gas source 3 Driving gas source 4 Regulator 5 Regulator 6 Regulator 7 Electromagnetic valve unit 8 Precision regulator 9 Precision regulator 10 Open / close valve 11 Open / close valve 12 Open / close valve 13 Open / close valve 14 Open / close valve 15 Open / close valve 16 Open / close valve 17 Opening / closing valve 18 Volume tube 19 Quantitative injector 20 Sample cell 21 Reference cell 22 Sample 23 Constant temperature container 24 Pressure transducer 25 Pressure transducer 26 Pressure transducer 27 Vacuum boost pump 28 Vacuum pump 29 Vertical unit 30 Forward / reverse motor 31 Feed screw 32 Control means 33 computing means 34 output means 35 constant temperature chamber 51 injector head 52 diaphragm 53 gas inlet 54 gas outlet 55 inlet valve lot 56 diaphragm lot 57 outlet valve lot 58 ac Cheater 59 Actuator 60 Actuator 61 Gas introduction pipe 62 Gas injection pipe 63 Buffer member 64 Connecting member 65 Insert joint 66 Insert joint 67 Fixing ring

Claims (2)

[Claims] 1. A thermostatic chamber in which the temperature inside the tank is controlled to a predetermined temperature is provided so that the gas introduced from the adsorbing gas source and the non-adsorbing gas source is kept at a constant pressure by a precision regulator and can be switched by an on-off valve. Has a system for injecting the adsorbed gas or the non-adsorbed gas into the upper pipe of the sample cell detachably attached to the upper pipe of the sample cell through a pipe introduced from the sample cell upper pipe to a vacuum pump provided outside the temperature-controlled room. It has a system in which a volume pipe is provided between a plurality of on-off valves and an on-off valve, and the adsorbed gas or non-adsorbed gas and the vacuum pump are attached to the upper pipe of a reference cell detachably provided outside the temperature-controlled room. It has a system with an open / close valve that can be switched, and a pressure transducer is installed in each of the sample cell upper pipe and the reference cell upper pipe, and the pressure transducer is connected to the vacuum pump. A vacuum gauge is provided in the pipe to be provided, and control means for controlling the on-off valve and fixed quantity injector and detecting a pressure signal and control means for monitoring and controlling the control means and output means for outputting the analysis and control result are provided. A pore size distribution measuring device characterized by: 2. A diaphragm, which is closely arranged so as to cover the surface of the injector head in which one of a gas inlet and a gas outlet penetrating through the injector head in parallel is provided, and the diaphragm is provided with a fixing ring all around the injector. It is tightly fixed to the head and a diaphragm lot is provided in the central part, and an inlet valve lot that presses and closes the gas inlet from the outer surface of the diaphragm and an outlet valve lot that presses and closes the gas outlet from the outer surface of the diaphragm are provided. The metered dose injector for use in the invention of claim 1, further comprising actuators for driving the diaphragm lot and the outlet valve lot, respectively.