JPS61205843A - Method and apparatus for measuring fine pore size of porous body - Google Patents

Abstract

PURPOSE:To measure even a micron order fine pore size with good accuracy, by calculating the available diameter of a porous body on the basis of data obtained by applying volumetric variation to the gas in the cell receiving the porous body. CONSTITUTION:A combination of a porous body 1 and a cell 2, a gas volume detection means 3, a gas pressure detection means 4, an operation means 5, a display means 6 and a gas volume varying means 15 are provided. The cell 2 is filled with a specimen and heated and evacuated to once bring the cell 2 and the bellows 8 cooperated with said cell 2 to a vacuum state and, thereafter, the cell 2 is filled with inert gas so as to obtain predetermined pressure. Next, the motor in the means 15 is driven to apply volumetric variation to the gas in the cell 1 at an angular speed omega. The data of the volumetric variation value is inputted to an operation part 10 from an operation table 14 and the means 15 is controlled on the basis of said data. Next, sampling data with respect to the volume of gas is outputted to the operation part 10 as a displacement detection signal from the means 3. The pressure of the gas is detected by the means 14 to be outputted to the operation part 10. The operation part 10 transmits the data outputted from the means 3, 4 to a data memory part 11 to store the same therein.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for measuring the pore diameter of a porous body and a measuring device thereof, and more specifically, a method and a measuring device for measuring the micro pore diameter in a porous body. Regarding the measuring device.

[Prior art and its problems] Conventionally, as a simple method for measuring the pore diameter in a porous body,
There are mercury intrusion method and nitrogen adsorption method [Catalyst Engineering Account 4.
[Catalyst Basic Measurement Method JP51. (1964), Tominaga Kei, “Adsorption”, Kyoritsu Zensho.

pH5 (1965), “Porous Materials”, by Ren Komaki,
See Gihodo, p. 45 (1975), etc.].

However, these methods cannot easily and accurately measure micro pore diameters of 2 nm or less. Therefore, the above methods cannot also measure micro pore diameter distribution, and X-ray diffraction etc. complex measurement methods had to be used.

This invention was made based on the above circumstances,
It is an object of the present invention to provide a method and apparatus that can measure micro pore diameters smaller than 2 nm with high accuracy and, therefore, can also measure pore diameter distribution.

[Means for solving the above problems] The outline of the present invention for solving the above problems is to apply periodic volume fluctuations to a gas in a cell housing a porous body, and to control the volume fluctuations and pressure of the gas. The phase difference and amplitude of the fluctuation are detected, and this phase difference, each amplitude, and the data regarding the particle size determined in advance are used as basic data, and from this basic data, according to the simulation formula obtained from the diffusion theory formula, A parameter that is a function of the gas diffusion coefficient and the particle diameter of the porous body is calculated, and the calculated parameter is applied to a calibration curve between the parameter and the effective pore diameter to calculate the effective pore diameter of the porous body. A method for measuring the pore diameter of a porous body, which includes a porous body and a cell into which a gas is inscribed, a gas volume varying means for varying the volume of the gas in the cell, and a gas volume detecting means for detecting the volume of the gas. , using the gas pressure detection means for detecting the pressure of the gas, the data obtained from the gas volume detection means and the gas pressure detection means, and the data regarding the particle diameter obtained in advance as basic data, from this basic data, the diffusion theory is According to the simulator 1 formula obtained from the formula, a parameter that is a function of the gas diffusion coefficient in the pore and the particle diameter of the porous body is calculated, and the calculated parameter is applied to a calibration curve between the parameter and the effective pore diameter. A device for measuring the pore diameter of a porous body, comprising a calculation means for calculating the effective pore diameter of the porous body, and a display means for outputting and displaying the calculation result output from the calculation means.

The basic principle of this invention is to apply physical perturbation to the gas that is the atmosphere of the porous body, detect the phase difference between the volume fluctuation and pressure fluctuation of the gas, and their respective amplitudes. Using the particle size of the prepared porous material as basic data, parameters are calculated by the nonlinear least squares method using a simulation formula derived from a diffusion theory formula according to the frequency response method, and then the parameters are calculated using the previously determined parameters and the effective pore diameter. The effective pore diameter is determined by applying the calculated parameters to the calibration curve. In addition,
In this invention, if the effective pore diameter corresponding to the frequency corresponding to the pore volume, which can be determined by the above-mentioned simulation formula, is determined, this is equivalent to determining the pore size distribution.

In other words, according to the method and apparatus of the present invention, when the pore diameters of a porous body have a distribution, it is also possible to measure the pore diameter distribution.

Next, the measuring method of the present invention will be explained in detail together with the measuring device of the present invention using the drawings.

FIG. 1 is an explanatory diagram showing a measuring device of the present invention for implementing the method of the present invention.

As shown in FIG. 1, the apparatus for measuring the pore diameter of a porous material consists of a cell 2 that houses a porous material 1 and seals in gas;
a gas volume varying means 15 for varying the gas volume therein;
a gas volume detection means 3 that measures the volume of the gas and outputs the measurement result as an electrical signal; a gas pressure detection means 4 that detects the gas pressure in the cell 2; and the gas volume detection means 3 and the gas pressure. Using the data output from the detection means 4 and the data regarding the particle diameter of the porous body l obtained in advance using an electron microscope, etc. as basic data, predetermined parameters are calculated from the simulation formula described later from this basic data, and these parameters are a calculation means 5 that calculates the pore diameter of the porous body 1 by applying it to a calibration curve, and outputs the calculation result;
The display unit 6 is configured to include a display unit 6 for displaying the calculation result outputted from the calculation unit 5.

The cell 2 has a gas exhaust means such as a gas exhaust valve 1.
6, a combination of a vacuum pump, etc., a combination of gas introduction means such as a gas cylinder, a pipe, a gas introduction valve 17, etc., a constant temperature means for cooling or heating the cell 2 and maintaining the inside of the cell z at a constant temperature, such as a cooler and a heater. The gas volume varying means 1
5 and is made of heat-resistant and pressure-resistant material. In the method of the present invention, a porous body 1 is loaded into a cell 2, and a gas such as an inert gas such as krypton or xenon, nitrogen, hydrogen, or various hydrocarbons is sealed into the cell 2 through the gas introduction means. , the temperature at the time of measurement is -273~100
°C, preferably -196 to 30 °C, and the gas pressure during measurement is 0.1 to 1,000 Torr, preferably 3 to 30 °C.
It is set to 20 Torr.

If the temperature at the time of measurement is too high, the amount of gas stored in the porous body 1 may be too small, making it difficult to obtain a response to pressure fluctuations. Furthermore, if the pressure at the time of measurement is too high or too low, it may be difficult to obtain a response to pressure fluctuations.

The gas volume variation means 15 is for periodically imparting a constant gas volume variation to the gas in the cell 2, and includes, for example, a bellows 8 connected to the cell 2 via a pipe, and a bellows 8 connected to the cell 2 via a pipe. The driving means 9 for driving the telescopic movement may be a combination of a cam and a motor, for example. However, this gas volume varying means 15 is not limited to the above structure, but may have any structure as long as it has the above function. It can also be comprised of a drive means, such as a motor, for reciprocating the syringe.

The gas volume detection means 3 detects the variation in the gas volume and outputs the detection result as an electric signal, such as a voltage signal or a current signal, to the calculation means 5. A photodiode that outputs the displacement detection signal as an electric signal can be used.

This gas volume detecting means 3 normally controls the gas in the cell 2 at a rate of 0.06 to 2,000 rad/min, preferably 0.
．． The volume variation is applied at an angular velocity of 4 to t, ooo radians/min so that the volume variation rate is 20% or less, preferably 10% or less.

The reason why the angular velocity is set in this range is that when the angular velocity is small, it is for temperature control reasons, and when the angular velocity is large, it is due to mechanical limitations such as the motor, etc.
The reason why the volume variation rate is set within the above range is to ensure accurate correlation with the simulation formula described later.

The gas pressure detection means 4 detects the gas pressure within the cell 2 and outputs the detected value to the calculation means 5 as an electrical signal, such as a voltage signal or a current signal, and is, for example, a pressure sensor with a fast response speed. and an electric signal output means for converting the pressure detected by the pressure sensor into an electric signal and outputting the same as a pressure detection signal.

The calculation means 5 calculates the displacement detection signal outputted from the gas volume detection means 3 and the pressure detection signal outputted from the gas pressure detection means 4, which are outputted from, for example, an operation console and observed in advance using, for example, an electron microscope. Porous body 1 obtained by
and the diffusion coefficient of the porous body 1, which has been determined experimentally in advance and entered from the operation console, and from the data on the particle size, statistical data about this particle size, such as the average particle size, are input. The standard deviation of the particle size distribution and the like are calculated, and the volume variation V is determined from the displacement detection signal.
(=Vi/Vo), calculate the pressure fluctuation P (=Pi/Pa) from the pressure detection signal, and calculate the volume fluctuation V, the pressure fluctuation P, the phase difference ψ between the volume fluctuation V and the pressure fluctuation P, Parameter P(2) and parameter K are calculated from the angular velocity ω regarding the fluctuation in the gas volume and the diffusion coefficient using equations (1) to (9) shown below, and the calibration values obtained in advance by the procedure described below are calculated. The effective pore diameter is calculated by applying the parameters of the calculation results to the line.

A calculation unit 10 that outputs the calculation result, and the calculation unit 10
A data storage section t stores various calculation data calculated in
i, a calibration curve storage unit 12 that stores data indicating the calibration curve and outputs it to the calculation unit 10;
1) to (9), and a calculation formula storage unit 13 that outputs necessary calculation formulas according to the calculations obtained by the calculation unit 10. Note that the above formulas (1) to (7) and (8)
) or (9) to calculate the effective pore diameter of the porous body 1 by inputting support for the selection of the formula to the calculation unit IO via the console 14, for example.

[If the porous body l is mono-systemic, 31 (V/P)Sinψ = δ3. , (1
)(V/P)Cosψ−1=δ3c (2)
However, [when there is a distribution in the pore diameter of the porous body 1] When there is a distribution in the pore diameter of the porous body 1, use formulas (8) and (9) instead of formulas (1) and (2) above. do.

(V/P)Sinψ=ΣK(i)'! (i)=K(1
) ”5(1)+K(2) '5(2)+” ” ”(
V/P) Cosψ−1=ΣK(i) ”C(i)=K(
1) ”c(1)+K(2) ”c(2)+” ” ”
The calculation means 5 is also capable of automatically controlling the gas volume varying means 15, the gas exhaust valve 16, and the gas introduction valve 17.

The display means 6 receives the calculation results output from the calculation section 10 and displays the pore size distribution based on the effective pore size and/or the effective pore size and parameters, and is, for example, a CRT display device, A line printer etc. can be used.

Here, the above-mentioned equations (1) to (9) are obtained based on diffusion theory equations. In other words, the volumetric fluctuation of the system ■
is i ωt V=Veq(1-ve) (10)
However, the subscript eq indicates the equilibrium state, ω is the angular velocity, V is the amplitude of the volume change, and L is the time.

The pressure fluctuation P is as follows: P=Peq(1+pei(''+ψ)) (11) where ψ is the phase difference and P is the amplitude.

The variation in gas concentration C in the pores is as follows.

C=Ceq(1+yei("+ψ-") (12)
At this time, the amplitude γ and the phase difference χ depend not only on ω but also on the pore inner layer.

The above can be solved mathematically by assuming that gas diffusion in pores follows Fick's equation and that pores can be approximated to a one-dimensional flat plate model or a three-dimensional spherical model, which are easy to solve mathematically. Equations (1) to (8) are derived.

Further, the calibration curve is determined as follows.

That is, using a sample of a substance with known pore size, particle size, and particle size distribution, such as zeolite 13 This is also loaded into the cell 2. A volumetric variation is applied to the gas in the cell 2, and the angular velocity ω is changed a desired number of times (the number of changes is preferably at least 20 in order to improve the accuracy of the calibration curve.
), the displacement detection signal output from the gas volume detection means 3 and the pressure detection signal output from the gas pressure detection means are input to the calculation means 5. This calculation means 5 calculates the displacement detection signal, the pressure detection signal, and the operation console 14.
The average particle size and particle size distribution of the sample can be calculated using the data on the particle size of the sample inputted via the sample and the diffusion coefficient of the sample experimentally determined in advance and inputted via the operation console 14. The standard deviation etc. are calculated, the volume fluctuation V and the pressure fluctuation P are calculated, and the volume fluctuation V, the pressure fluctuation P, the volume fluctuation V and the pressure fluctuation P are calculated.
ψ, the angular velocity ω for the fluctuation of the gas volume
, and the diffusion coefficient, the parameter P(2) and the parameter K are calculated using equations (1) to (9), and the results of these calculations are output and stored in the calibration curve memory s12.

[Operation] The operation of the measuring device will be explained together with the procedure of the method of the present invention.

FIG. 2 is a flowchart showing the procedure for carrying out the measuring method of the present invention using the measuring device.

(1) First, gas and a sample are loaded into the cell 2.

That is, a sample is loaded into the cell 2 and heated and evacuated. After the inside of the cell 2 and the bellows 8 communicating therewith are once evacuated to a vacuum, the inside of the cell 2 is filled with an inert gas such as cannon to a predetermined pressure. In addition, at this time, the gas introduction operation etc. are performed by the calculation unit 1 in the measuring device.
It is convenient to program it to 0 so that it can be automatically controlled.

(2) Next, the motor in the gas volume varying means 15 is driven to vary the volume of the gas in the cell 2 at an angular velocity ω. The determination of the volume fluctuation value is carried out from the operation console 14 to the calculation unit 1.
0, and the gas volume varying means 15 is controlled by this arithmetic unit IO. Further, the angular velocity ω is assumed to be the initial angular velocity ω(1), and the input of this angular velocity ωC1) and the input of the final angular velocity ω(n) are also input to the calculation unit 10 via the console 14, and the calculation unit 10 The angular velocity in the gas volume varying means 15 is controlled. Note that this n
The value of is usually 20. In other words, the value of angular velocity is changed 20 times.

(3) Next, once the volume variation has started to be applied to the gas in the cell z, sampling data regarding the gas volume is outputted from the gas volume detection means 3 to the calculation section 10 as a displacement detection signal. Further, the gas pressure detection means 4 detects the gas pressure within the cell 2, and outputs sampling data regarding the gas pressure to the calculation unit 10 as a pressure detection signal. Incidentally, the relationship between the volume fluctuation and pressure fluctuation of gas is shown in FIG. Data is collected by transferring and storing the data to 11.

(5) The calculation unit 10 calculates the volume variation V, pressure variation P, and phase difference ψ from the data output from the gas volume detection means 3 and the gas pressure detection means 4. The calculation result is stored in the data storage unit 11.
Data on the particle diameter of the porous body 1 and data on the diffusion coefficient of the porous body 1, which have been measured by observing a sample using an electron microscope or the like, are inputted via the operation console 14. Statistical data regarding particle diameters, such as the average value of particle diameters, standard deviation of particle diameter distribution, etc., are computed in this computing section 10, and the computed results are also stored in data storage section 11.

(6) When the calculation unit 10 finishes collecting data regarding the angular velocity ω(1), the angular velocity is changed.

(7) Start changing the gas volume at the changed angular velocity, output sampling data from the gas volume detection means 3 and the gas pressure detection means 4 to the calculation unit IO, and calculate the volume fluctuation V in the calculation unit 10 in the same way as above. , the pressure fluctuation 21 phase difference ψ is calculated, and the calculation result is stored in the data storage unit 11.

The final angular velocity ω(n) set by the angular velocity ω of this repetition
Execute until.

(8) Once the various data regarding the angular velocities ω(1) to ω(n) have been collected, the calculation unit 10 calls the simulation formula from the calculation formula storage unit 13.

(V/P) Sinψ=Ka3s (t) (V/
P) Cosψ−1=K E 3c (2) or (V/P)Sinψ=ΣK(i) ” 5(i)(V/
P) Cosψ−1=ΣK(i) 8c(i)”K(1)
Shima (1) + K (2)'. (2)+□°.

Calculate.

i in equations (8) and (9) is determined based on the difference between the experimental value and the calculation formula in the case of simulation.

This can be determined manually, but it can also be determined automatically based on whether the sum of squares of residual liquid in the following equation is close to zero.

Then, once calculated, if Z is larger than 0.2, increase this i by one and calculate again, and if Z is larger than 0.2,
Determine whether it is greater than. Repeat this step by step.

(9) When the sample has a single diameter, the parameter P(2), which is a function of the particle diameter of the sample and the diffusion coefficient, is calculated using equations (1) and (2) above. Needless to say, equations (3) to (7) are called from the calculation formula storage section 13 in order to calculate this parameter.

(lO) After calculating the parameter P(2), this calculation unit 10
calls the calibration curve data from the calibration curve storage section 12,
The effective diameter d of the sample is calculated by applying the parameter P(2) to this calibration curve.

(11) Output the calculated effective diameter d of the sample to a display device, and display the result graphically on a CRT cathode ray tube, for example, or print it out on paper from a printer.

(12) On the other hand, when the sample does not have a single diameter but has a distribution in pore diameter, the calculation formula storage unit 13
From this, the parameter P(2), which is a function of the particle diameter of the sample and the diffusion coefficient, and the parameter P(2) are calculated using equations (8) and (3). Needless to say, equations (3) to (7) are called from the calculation formula storage section 13 in order to calculate this parameter.

(13) After calculating the parameter P(2), the calculation unit 10 reads the calibration curve data from the calibration curve storage unit 12, applies the parameter P(2) to this calibration curve, and calculates the effective diameter d of the sample. calculate.

(10 Correlate the calculated effective diameter d of the sample with the parameters, output it to a display device, and display the results graphically on, for example, a CRT cathode ray tube, or print out a list on paper from a printer.

[Effects of the Invention] According to the method of the present invention, based on the data obtained by varying the volume of gas in the cell 2 housing the porous body 1, a simulation is performed using a calculation formula derived from a diffusion theory formula, and the porous Since the effective diameter of the body l is calculated, it is possible to accurately measure micropore diameters of 2 nm or less, which was impossible with conventional methods and measuring devices. Furthermore, when the pore diameters of the porous body 1 have a distribution, the pore diameter distribution can also be measured. For this reason, this invention
It is also possible to track changes in the structure of micropores caused by various treatments in zeolite, which is a typical material with micropores.

Further, according to the apparatus of the present invention, the method of the present invention can be carried out automatically, and the pore diameter and pore diameter distribution of a porous body of 2 nm or less can be measured with high precision.

[Example 1 Next, examples of this invention will be shown.

(Example 1) Using the measuring device shown in Fig. 1, zeolite)ZS was
Approximately 5 g of M-5 was accurately weighed and loaded. The inside of the cell is maintained at 0°C, the inside of the cell is evacuated once, and then xenon as a measurement gas is introduced into the cell, and the gas pressure inside the cell is increased to 7T.
arr and brought to equilibrium. After that, the angular velocity ω is in the range of 0.4 to 260 rad/min, and the volume variation rate is 4%.
As a result, a volume variation was applied to the gas in the cell.

The volume fluctuation is detected by the gas volume detection means and inputted to the calculation means as a displacement detection signal, and the fluctuation in gas pressure that fluctuates in response to this volume fluctuation is detected by the gas pressure detection means and calculated as a pressure detection signal. entered into the means.

The value of the angular velocity ω was changed 20 times to give a volumetric variation to the gas in the cell, and the data was input into the calculation means each time.

The calculation section performs a simulation based on the input data,
The Sin term and C in the above equations (1) and (2)
The ax term and logω were calculated. The result of the calculation is
Shown in the figure.

At the same time, the gas diffusion parameter P(2) and the factor were determined. Yfi zeolite and zeolite MS-
The effective pore diameter was determined to be 6 angstroms from this P(2) using the calibration curve obtained from the 13X simulation (see FIG. 5). This value was consistent with the value obtained by X-ray diffraction, which is a method for analyzing the structure of substances.

(Example 2) The measuring apparatus shown in FIG. 1 was prepared in the same manner as in Example 1 except that a porous material mixture [zeolite MS-5A/zeolite Ms-13X, weight ratio = l/2] was used as the sample. , the simulation is performed up to i=2, and the above-mentioned (
Equation 8), the Sin term and Cax term in Equation (8), and logω were calculated, and the results of the calculation are shown in FIG.

The parameter P(2) for i=1 and i=2 agreed with that of zeolite MS-5A and zeolite MS-13X, and K and the mixing ratio showed a good correlation. Therefore, in this way, different This simulation method can also be applied to samples with pore sizes.
Measurements of pore size distribution can also be made.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing a measuring device of the present invention that implements the measuring method of the present invention, FIG. 2 is a flowchart showing the procedure for measuring with the measuring device, and FIG. A relationship diagram showing the relationship between volume variation and pressure variation when volume variation is applied, Figures 4 and 6 are frequency characteristic diagrams when actually measured with the measuring device, and Figure 5 is a characteristic curve showing the calibration curve. It is a diagram. DESCRIPTION OF SYMBOLS 1... Porous body, 211a * cell, 3... Gas volume detection means, 4... Gas pressure detection means, 5... Calculation means, 6... Display means, 15... Gas volume Variable means. Patent Applicant: Idemitsu Kosan Co., Ltd. Agent, Patent Attorney: Naoki Fukumura Procedural Amendment Statement 1985 Patent Application No. 47265 2 Title of Invention Method for Measuring the Pore Diameter of Porous Materials and Measuring Apparatus 3 Make the Amendment Patent applicant address: 1-1 Shiratama-chome, Maruno, Chiyoda-ku, Tokyo Name: Idemitsu Kosan Co., Ltd. Representative: Idemitsu Shuben 4 Agent address: Karakawa Building 2, 6-3-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Floor 8 Contents of amendment (1) The description in the "Claims" shall be amended as shown in the attached sheet. (2) Line 3 from the bottom of page 3 of the specification, lines 5-6 of page 5, line 11 of page 10, line 12 of page 10, line i. Page 13th line, page 13, 3rd line from the bottom, page 15, line 10, page 5, line ii, page 15, line 12, page 17, line 1, page 17, 2nd from the bottom
line, and lines 6 to 5 from the bottom of page 18, “
"Pressure fluctuation" is corrected to "pressure response." (3) “and,” stated on page 4, line 12 of the specification.
" is corrected to ", and". (4) “The statement stated in the 6th line from the bottom of the 4th page of the specification
Correct "from," to "and." (5) The formula stated in the bottom line of page 19 of the specification shall be amended to the following formula. (6) 20th page, line 7, same page, 11th line, same page, 13th line, 21st page, 3rd line, same page, 7th line, same page, 9th line, 23rd page, line 17, same page 20th
Correct rP(2)J described in line 1 and page 24, line 12 to r [P(2) ] 2 J. (7) r7T described in the first line of page 23 of the specification
orr J, r8.0 or 12. Correct to ITorr J. (8) "and" written in the third line from the bottom of page 23 of the specification shall be amended to ",". (9) After rMS-13XJ (7) described in the second line from the bottom of page 23 of the specification, “Oyobi MS-5AJ
Please join. (lO) "
Correct ``can also do'' to ``can also do''. (11) Correct each of FIGS. 2, 4, 5, and 6 in the drawings as shown in the attached sheets. Attachment [Claims] ``(1) Applying gas and periodic volume fluctuations to a cell containing a porous body, detecting the phase difference between the volume fluctuations of the gas and the pressure response, and the respective amplitudes; Using data on the phase difference, amplitude, and particle size determined in advance as basic data, from this basic data, a function of the gas diffusion coefficient in the pores and the particle size of the porous body is calculated according to the simulation formula obtained from the diffusion theory formula. A method for measuring the pore diameter of a porous body, which comprises calculating a certain parameter and applying the calculated parameter to a calibration curve between the parameter and the effective pore diameter to calculate the effective pore diameter of the porous body. (2) Porous body and a cell for sealing a gas, a gas volume varying means for varying the volume of gas in the cell, a gas volume detecting means for detecting the gas jewel, a gas pressure detecting means for detecting the pressure of the gas, and Using the data obtained from the gas volume detecting means and the gas pressure detecting means as basic data and the data regarding the particle size obtained in advance, the gas in the pores is determined according to the simulation formula obtained from the basic data proof 1 diffusion theory formula. a calculation means that calculates a parameter that is a function of a diffusion coefficient and a particle diameter of the porous body, and calculates the effective pore diameter of the porous body by applying the calculated parameter to a calibration curve between the parameter and the effective pore diameter; A device for measuring the pore diameter of a porous body, comprising display means for outputting and displaying the calculation results output from the means.

Claims (2)

[Claims] (1) Periodic volume fluctuations are applied to the gas in the cell that houses the porous body, and the phase difference and respective amplitude between the gas volume fluctuation and pressure fluctuation are detected, and the phase difference, amplitude, and predetermined Using the data regarding the particle size as basic data, from this basic data, a parameter that is a function of the gas diffusion coefficient in the pores and the particle size of the porous body is calculated according to the simulation formula obtained from the diffusion theory formula, and the parameter and A method for measuring the pore diameter of a porous body, characterized in that the effective pore diameter of the porous body is calculated by applying the calculation parameters to a calibration curve with the effective pore diameter. (2) A cell that encloses a porous body and a gas, a gas volume varying means for varying the volume of the gas in the cell, a gas volume detecting means for detecting the volume of the gas, and a pressure of the gas. Using the gas pressure detection means, the data obtained from the gas volume detection means and the gas pressure detection means, and the data regarding the particle diameter determined in advance as basic data, from this basic data, according to the simulation formula determined from the diffusion theory formula, A calculation that calculates a parameter that is a function of the gas diffusion coefficient in the pores and the particle diameter of the porous body, and applies the calculated parameter to a calibration curve between the parameter and the effective pore diameter to calculate the effective pore diameter of the porous body. 1. An apparatus for measuring a pore diameter of a porous body, comprising: a means for measuring a pore diameter of a porous body; and a display means for outputting and displaying a calculation result output from the calculation means.