JP2779913B2 - Pore distribution measuring device and metering injector - Google Patents

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 pore distribution, surface area and the like of the physical properties of the solid by the displacement of the amount of adsorption.

[0002]

2. Description of the Related Art Conventionally, as a pore distribution measuring apparatus which is used by measuring an equilibrium pressure at the time of adsorption, Japanese Patent Publication No. 53-31 is publicly known.
5 Automatic adsorption / desorption 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 apparatus, Japanese Patent Publication No. 6-23676
There are two types, a constant volume method or a constant volume method which has long been known based on the principle used in an adsorption amount measuring device, and 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 based on the constant flow rate method described in Japanese Patent Publication No. 4-5341, a mass flow controller having a mass flow meter stabilizes the flow rate of an adsorbed gas and continuously flows the adsorbed gas into a sample cell for measurement. The purpose is to do. Therefore, according to the prior art described in the publication, there is a problem that the reliability of the adsorption result is poor because the adsorption pressure is measured at a non-equilibrium pressure. In addition, there is a problem that the production cost is increased due to the provision of an expensive mass flow controller and a control signal system.

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

Therefore, when the adsorption amount Vn is determined by the constant volume method described in the official gazette, iterative calculation represented by the following equation 1 is required.

[0006]

(Equation 1)

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

In the configuration of the measuring apparatus based on the volumetric method, since the volume chamber Vs is a thermostat and the sample cell is arranged in a Dewar bottle, the temperature of the thermostat in the volume chamber is usually about 30 to 40 degrees higher than room temperature. After communicating with the environment of extremely low temperature such as liquid nitrogen from, store to equilibrium pressure and measure. According to this, first, it is necessary to provide a stabilization time for the adsorbed gas introduced into the volume chamber Vs to expand until the temperature of the chamber reaches the temperature of the constant temperature chamber. Must be stored until This is because if the internal pressure of the sample cell is still changing after closing the on-off valve in order to start the next adsorption measurement, not only the accurate adsorption amount cannot be obtained, but also the measurement error This is because they are accumulated and become extremely poor in reliability. Furthermore, in physical adsorption phenomena such as nitrogen gas adsorption, although the adsorption phenomena occur almost instantaneously, the main member who takes a long time until the adsorption equilibrium in the volumetric method is the main member of the volume chamber Vs and the sample cell Vd. The main factors are distance, volume, and temperature difference. Therefore, the conventional volumetric method has a problem that a measurement time is required.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method for performing measurement based on complete adsorption equilibrium, 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, there is provided a constant temperature chamber in which the temperature in the bath is controlled to a predetermined temperature, and a constant temperature chamber provided outside the constant temperature chamber by an adsorption gas source and a non-adsorption gas source. The gas introduced into the chamber is regulated to a constant pressure by a precision regulator, and is provided switchably with an on-off valve. The adsorbed gas or non-adsorbed gas is injected by a quantitative injector into the upper piping of the sample cell that is detachably installed outside the constant temperature chamber. It has a system to do. Further, there is provided a system in which a plurality of open / close valves and a volume pipe provided between the open / close valves are provided on a pipe led from the upper pipe of the sample cell to a vacuum pump provided outside the constant temperature chamber. Further, there is provided a system in which a plurality of open / close valves are provided in an upper pipe of a reference cell detachably provided outside the constant temperature chamber so as to be able to switch between the adsorbed gas or the non-adsorbed gas and the vacuum pump. 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 a pipe led to the vacuum pump, and control means for controlling the on-off valve and the metering injector and detecting a pressure signal. A pore size measuring apparatus comprising: a calculation means for monitoring and controlling a control means and data analysis; and an output means for outputting a result of analysis and control.

According to the second aspect of the present invention, there is provided a diaphragm which is closely attached so as to cover a surface of the injector head in which one of a gas inlet and a gas outlet is opened penetrating the injector head in parallel. The periphery is closely 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. A metering injector used in the invention according to claim 1, comprising:

[0012]

According to the first aspect of the present invention, there is provided a constant temperature chamber in which the temperature in the bath is controlled to a predetermined temperature, and a gas guided from an adsorption gas source and a non-adsorption gas source provided outside the constant temperature chamber to the constant temperature chamber. It has a system that is set to a constant pressure by a precision regulator and is switchable by an on-off valve, and is injected into the upper piping of the sample cell by a quantitative injector. According to this, the sample cell and the upper pipe are a single container having an extremely low volume and communicating with almost the same inner diameter. The standard state (P = 760To)
(rr, T = 273 ° K) The fixed amount of the adsorbed gas is injected by a fixed amount injector with a known injection amount. The gas injected by the metering injector at a time is extremely small, so that high-resolution measurement is possible.In addition, adsorption occurs instantaneously and has a short time to reach equilibrium pressure in a low-volume sample cell. It is a pore distribution measuring device.

The metering injector according to the second aspect of the present invention is provided in a constant temperature chamber in which the temperature in the bath is controlled to a predetermined temperature, and a gas regulated to a constant pressure by a precision regulator is led to a gas inlet. The guided 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 open, 2: gas suction, 3: airtight, 4: outlet valve open. , 5: gas injection, 6:
The operation of sealing is repeated to inject gas into the sample cell. The gas collected by the airtightness of 3 is always a constant amount due to the environment that is precisely adjusted in both temperature and pressure.
The inside of the sample cell to be injected has the effect of being quickly injected because of the pressure lower than the injection pressure (precision regulator set pressure).

According to the present invention described above, the measurement based on the complete adsorption equilibrium can be performed, and the measurement can be performed to shorten the measurement time.

[0015]

Embodiments of the present invention will be described below in detail.

FIG. 1 shows an embodiment of the first aspect of the present invention. According to this embodiment, a constant temperature chamber (35) in which the temperature in a bath is controlled to a predetermined temperature is provided, and an adsorption gas source provided outside the constant temperature chamber The gas introduced from (1) and the non-adsorbed gas source (2) to the constant temperature chamber is adjusted to a constant pressure by the precision regulators (8) and (9), and provided to be switchable by the on-off valves (10) and (11). The adsorbed gas (1) or the non-adsorbed gas (2) is placed in the upper pipe of the sample cell (20) detachably provided in
Is injected by a quantitative injector (19). Further, a volume provided between a plurality of on-off valves (15), (16), (17) and a plurality of on-off valves is provided on a pipe leading from an upper pipe of the sample cell (20) to a vacuum pump (28) provided outside the constant temperature chamber. There is a system provided with a pipe (18). Furthermore, a plurality of on-off valves () can be switched between the adsorbed gas (1) or the non-adsorbed gas (2) and the vacuum pump (28) in an upper pipe of a reference cell (21) detachably provided outside the constant temperature chamber. 12) There is a system provided with (13) and (14). Further, pressure transducers (24) and (25) are provided respectively in the sample cell upper pipe and the reference cell upper pipe.
And a vacuum gauge (2
6), a control means (32) for controlling the on-off valve and the fixed-quantity injector (19) and detecting a pressure signal, and a calculation means (33) for monitoring and controlling the control means and analyzing data, and analyzing and controlling results. A pore distribution measuring device comprising an output means (34) for outputting.

Further, in the embodiment, gas or air guided from the driving gas source (3) for driving the on-off valve is regulated by the regulator (6), and is controlled via the solenoid valve unit (7) driven by the control means. And 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 for adjusting the cells (20) and (21) to the adsorption temperature. The vertical unit (29) of the embodiment has a configuration in which vertical movement is realized by a feed screw (31) and a forward / reverse rotation motor (30). Further, regulators (4) and (5) provided when there are pressure fluctuations of the adsorbing gas source (1) and the non-adsorbing gas source (2) which cause error of the precision regulators (8) and (9), and HK
A vacuum booster pump (27) such as an oil diffusion pump or a turbo-molecular pump provided when a high vacuum is required for precise micropore analysis by a method is also described.
It should be noted that the adsorption amount measuring apparatus does not include a mantle heater, a temperature control system thereof, and a temperature control system of a constant temperature chamber, which are necessarily used for pretreatment vacuum degassing.

FIG. 4 shows another example of the embodiment of the present invention, in which precision regulators (8) and (9) for adjusting the pressures of the adsorption gas source (1) and the non-adsorption gas source (2) are used in common. This is an application example of the pore distribution measuring device according to claim 1 of the present invention, in which one of the on-off valve (13) and the on-off valve (17) is omitted.

FIG. 2 shows an embodiment of the invention according to claim 2, in which one of a gas inlet (53) and a gas outlet (54) passing through the injector head (51) in parallel. A diaphragm (52) is disposed in close contact with the opening of the injector head so as to cover the plane of the injector head. The diaphragm is tightly fixed to the injector head all around by a fixing ring (67), and a diaphragm lot (56) is provided in the center. It is provided.
A gas introduction pipe (61) led from the adsorption gas source (1) or the non-adsorption gas source (2) is provided at the other end of the gas inlet (53).
A gas injection pipe (62) led to the upper pipe of the sample cell (20) is connected to the other end of the gas outlet (54) by the insertion joint (65).
6). Further, the gas inlet (5
3) an inlet valve lot (55) for closing one side by pressing the outer surface of the diaphragm (52) and the gas outlet (54).
An outlet valve lot (57) for closing one of the two is pressed from the outer surface of the diaphragm (52), and an actuator (58) (59) (60) for driving the inlet valve lot, the diaphragm lot and the outlet valve lot respectively. A metering injector used in the invention according to claim 1. 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 frame (52) in order to make the diaphragm lot (56) detachable. A set screw or an actuator (58) (59) (6) for detachably fixing the fixing ring (67).
The configuration of the drive system of 0) is omitted.

In order to use the pore distribution measuring device of the present invention described above, a sample cell (20) into which a sample (22) has been charged is mounted, and on-off valves (15) and (16) are opened and closed as necessary. The valve (17) is alternately opened and closed alternately, the inside of the sample cell (20) is evacuated while being careful not to suck the sample (22), and heating vacuum degassing is sufficiently performed by a mantle heater.

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

Next, all the on-off valves are closed, and the thermostatic vessel (23)
Is slowly lifted by the upper and lower 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 store the adsorbed gas in the reference cell (2).
The liquid is introduced into 1) for about 3 to 5 minutes to generate liquefied gas inside the reference cell (21), and the on-off valve (14)
Close and seal. The inside of the sealed container is provided with a pressure transducer (25) to provide an accurate saturated vapor pressure Ps of the adsorbed gas throughout the subsequent measurement.

Next, the on-off valve (12), on-off valve (13), and on-off valve (17) are opened from a state in which all on-off valves are closed, and gas in the piping is purged, and all on-off valves are closed. Here, the on-off valve (11) is opened, and a non-adsorbed gas typified by helium gas is introduced.
A predetermined amount of gas is injected at 0), and after a predetermined time, measurement is performed by a pressure transducer (24). This operation is performed at least ten or more times, and the slope of the pressure rise is obtained by the least square method. This measured data provides the apparent or dead volume value at the refrigerant temperature of the strict sample cell (20) with the sample volume subtracted.

Next, the on-off valves (15) and (16) and the on-off valve (17) are alternately opened and closed alternately as necessary, and the non-adsorbed gas inside the sample cell (20) is taken care not to suck the sample (22). After sufficient purging of on-off valves, the on-off valves (12) and (13) are changed from the state in which all on-off valves are closed.
Open (17) to purge residual gas in the piping and close all on-off valves. Here, the on-off valve (10) is opened to introduce the adsorbed gas, and the gas is injected into the sample cell (20) in a fixed amount by the fixed amount injector (19). By performing the measurement, adsorption isothermal data can be obtained. At this time, the fixed quantity injector (19)
If the injection is measured once each time, an analysis result with a large number of measurement points and high resolution accuracy can be obtained, and if the measurement is performed after performing multiple injections, it will be a simple measurement in a short time, and the resolution and measurement time according to the purpose Is obtained. In order to use the pore distribution measuring device of the present invention most effectively, the measuring mode according to the analysis purpose is set as a program in advance by the arithmetic means (3
It is desirable to register in 3) and use them appropriately.

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

Next, in order to obtain desorption isotherm data according to the embodiment described in the present application, the data is started near the saturated vapor pressure at the end of the adsorption measurement. In this case, the on-off valves (15) and (17) are opened, the inside of the volume tube (18) is evacuated in advance, and then the on-off valves (15) and (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) reaches an adsorption equilibrium. In this case, the amount of desorbed gas is determined based on Equation 1 by the constant volume method.

Conventionally, analysis of the pore distribution by the BJH method or the DH method has generally been carried out by the desorption isotherm. However, the literature (Yoshio Morioka, Surface, Vol. 28, 598/1990) describes "fine porous materials. As shown in “Pore size distribution and network structure of pores”, it is clear that the adsorption measurement method according to the measurement method described in the present application is useful because the analysis by the adsorption isotherm is suitable for the analysis of the pore distribution. It is. Therefore, the case of performing the desorption measurement according to the present invention is limited to the case of using the analysis of the hysteresis characteristic of the adsorption / desorption isotherm by the pot-shaped pore. However, according to the embodiment of the present invention, the measurement by perfect adsorption equilibrium is possible. .

The pore distribution measuring apparatus according to the present invention can be particularly noted in that a highly accurate and flexible measurement pattern can be selected in the adsorption measurement. However, to determine the adsorption gas amount Vn by the adsorption measurement method described in the present application, the following method is used. It can be obtained very simply as in Equation 2.

[0029]

(Equation 2)

According to this, when the amount of adsorption at an arbitrary relative pressure is obtained, the amount of adsorption can be obtained instantaneously without performing a complicated repetitive calculation as shown in Expression 1. In addition, a measurement error due to the measurement method is small, and a highly accurate measurement can be performed by a synergistic action that does not generate a cumulative error due to the adsorption calculation.

[0031]

According to the present invention described in detail, the following effects can be obtained by adopting the above configuration.

The adsorption measurement method of the present invention is not a method in which the measurement is carried out while flowing an adsorption gas, but a method in which a complete adsorption equilibrium pressure is measured and obtained. Further, since an expensive mass flow controller and a control signal system are not required, the manufacturing cost is reduced.

Since the communication operation with the volume chamber Vs is not required as in the constant volume method, the volume is reduced to only the sample cell volume Vd, the arrival time of the adsorption equilibrium pressure is shortened, and the skip operation for executing the fixed quantity injector plural times. , A flexible measurement pattern that does not generate an error is possible. Similarly, the measurement accuracy is high because the absolute pressure measurement method measures only the adsorption equilibrium pressure instead of the measurement by the differential pressure measurement. Similarly, a higher measurement accuracy can be obtained by a measurement method that does not cause a cumulative error in the calculation of the amount of adsorption.

Further, as shown in the embodiment of the present invention, both the driving method of the on-off valve and the driving method of the fixed quantity injector are ON-O.
Because of the FF control, there is also an effect that it can be manufactured at low cost without requiring an analog control signal such as a mass flow controller or a leak valve.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram showing a first embodiment of the present invention.

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

FIG. 3 is a sectional view showing the operation of the second aspect of the present invention.

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adsorption gas source 2 Non-adsorption gas source 3 Driving gas source 4 Regulator 5 Regulator 6 Regulator 7 Solenoid valve unit 8 Precision regulator 9 Precision regulator 10 On-off valve 11 On-off valve 12 On-off valve 13 On-off valve 14 On-off valve 15 On-off valve 16 On-off valve Reference Signs List 17 ON / OFF valve 18 Volume tube 19 Metering injector 20 Sample cell 21 Reference cell 22 Sample 23 Constant temperature vessel 24 Pressure transducer 25 Pressure transducer 26 Pressure transducer 27 Vacuum booster pump 28 Vacuum pump 29 Vertical unit 30 Forward / reverse motor 31 Feed screw 32 Control means 33 arithmetic 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 Cheetah 59 Actuator 60 Actuator 61 Gas introduction pipe 62 Gas injection pipe 63 Buffer member 64 Connecting member 65 Insertion joint 66 Insertion joint 67 Fixing ring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 15/08

Claims (2)

(57) [Claims] 1. A constant temperature chamber in which the temperature in a bath is controlled to a predetermined temperature, a gas introduced from an adsorbing gas source and a non-adsorbing gas source is provided at a constant pressure by a precision regulator, and is switchable by an on-off valve. The adsorbed gas or non-adsorbed gas into the upper pipe of the sample cell detachably provided,
Actuator to control inlet valve lot and diaphragm lock
And the outlet valve lot are driven in sequence and injected into the sample cell.
A plurality of open / close valves and a volume pipe provided between open / close valves in a pipe leading from the upper pipe of the sample cell to a vacuum pump provided outside the constant temperature chamber. A system provided with an on-off valve so that the adsorption gas or the non-adsorption gas and the vacuum pump can be switched between upper and lower pipes of a reference cell detachably provided outside the room,
Control means and control means for providing a pressure transducer in each of the sample cell upper pipe and the reference cell upper pipe, providing a vacuum gauge in a pipe led to the vacuum pump, controlling the on-off valve and the metering injector, and detecting a pressure signal. A pore distribution measuring device comprising: an arithmetic means for monitoring and controlling data and an output means for outputting an analysis and control result. 2. A diaphragm, which is closely mounted so as to cover a surface of an injector head in which one of a gas inlet and a gas outlet that opens in parallel with the injector head is open, wherein the diaphragm is formed by a fixed ring around the entire periphery of the injector. A diaphragm lot is provided in the center part in close contact with the head and a diaphragm lot is provided, and 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. 2. The metering injector according to claim 1, further comprising an actuator for driving each of the diaphragm lot and the outlet valve lot.