JPS61102538A - Method and device for determining quantity of gas adsorbed by solid or desorbed from solid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the determination of the corresponding adsorption and/or desorption isotherms to determine the various morphologies of solids, such as surface area, pore size distribution and average pore volume. The present invention relates to a method and apparatus for determining or measuring the amount of a gas adsorbed or desorbed by a solid in such a way as to determine its chemical properties.

BACKGROUND OF THE INVENTION The measurement of morphological or structural properties of solids such as catalysts, catalyst supports, pigments, clays, minerals and composite materials has long been an unresolved goal of analytical science. .

For example, one very useful morphological property of solids is surface area. One of the most widely used techniques for surface area measurement is gas sorption techniques. This gas sorption technique uses a theoretical model in which the surface of the test solid (i.e., the adsorbent) is covered with tightly packed molecules of the adsorbed gas (i.e., the adsorbent). is considered to be covered by a single layer of Therefore, if the amount of adsorbent in the single layer (usually expressed in milliliter or d) can be determined, the area covered by the single layer can be calculated by dividing the number of molecules in the single layer by each molecule. It can be easily calculated from the product multiplied by the cross-sectional area of .

In 1958, Branauer.

Enrnet, and Teler proposed a mathematical formula called the BET equation to determine the amount of adsorbent in a single layer from the adsorption isotherm of the adsorbent (J, Am,
Chem.

Soc, Vol. 6o, 23o9 [). A cocote adsorption isotherm is a curve plotting the amount of adsorbent adsorbed onto a solid against the relative or equilibrium pressure of the adsorbent at a constant temperature. B to determine the surface area
In order to use the ET equation accurately, one must obtain a sufficient number of data points on the adsorption isotherm to be able to determine at least the point on the adsorption isotherm at which "monolayer capacity" occurs. Here, "single layer capacity" means 1 in the BET formula.
is a variable that represents the point on the adsorption isotherm at which a single layer of closely packed adsorbed molecules is present at the surface of the adsorbent.

Since this monolayer capacity generally occurs at a partial pressure of the adsorbent between K, about 18 and 2-5, the adsorption isotherm must be plotted over at least this partial pressure range in order to be able to calculate the surface area from the BET equation. It is desirable to know. However, what is meaningful is 0
From the adsorbent partial pressure in the range 1 to 1, the total adsorption isotherm range (adsorbent partial pressure is the fraction of the pressure at which condensation of the adsorbent occurs under any combination of constant volume and temperature conditions). Although it is not necessary to know for surface area purposes only, the information embodied in the total adsorption isotherm can nevertheless be used for other reasons, such as those discussed below. This is a very useful point.

Therefore, there is a motivation to develop analytical methods that have the ability to determine total adsorption isotherms. Adsorption isotherms are commonly determined in two general ways: gravimetrically and volumetrically.

In the gravimetric analysis method, the amount of gas adsorbed at equilibrium pressure is measured using a microbalance.

However, this gravimetric analysis method imposes limitations on the selection of the adsorbent (e.g. it is not easy to control the sample at liquid nitrogen temperature) and it is difficult to achieve effective temperature control of the sample. However, there are disadvantages such as the need for complex and expensive equipment to achieve the high sensitivity required for measurements. In contrast, volumetric analyzers are simple and inherently reliable.

In volumetric methods, the volume rather than the weight of the adsorbed gas is measured. Capacitive analyzers typically use nitrogen at a temperature of -195°C as the adsorbent. This type of device typically consists of a gas storage unit and an exhaust or vacuum source connected in parallel to a volumetric device having a known volume V1, such as a pallet or pipette, and referred to as a volumetric unit. It consists of The capacitance meter units can alternately be connected to a vacuum source or a gas storage unit via a series of stopcocks. On the other hand, the capacitance meter unit is connected in series via another stopcock to the sample unit, ie a chamber of known volume v2 which holds the test solid.

By operating the various stopcocks, the volumetric meter and sample unit are evacuated, and the evacuated volumetric meter is hermetically separated from the evacuated sample chamber. Thereafter, nitrogen gradually flows from the gas storage unit into the volumetric unit and fills the volumetric unit. Once the capacitance meter unit is filled, operate the stop cock again to completely seal the capacitance meter unit and measure the internal nitrogen pressure.

When a constant pressure P is achieved in the capacitance meter, the stopcock separating the sample chamber and the capacitance meter is opened, and the nitrogen N2 in the capacitance meter is introduced into the sample chamber and expanded. Both the sample chamber and the volume meter have the third volume V.

(i.e., V, + V2). The pressure in volume 1 is measured when it is constant and adsorption equilibrium is indicated. This equilibrium pressure is used to calculate the number of moles of N2 remaining in the gas phase. N2 adsorbed on solids
The number of moles of is the volume V of the capacitance meter.

It is equal to the sum of the number of moles of N2 initially present in the sample chamber plus the number of moles of N20 in the sample chamber of volume v2, and is smaller than the number of moles of gaseous N2 in the volume V after equilibrium (initial The number of moles in the volume v2 is zero in the cycle , but increases in successive cycles). The combined data of the amount of N2 adsorbed at a particular equilibrium pressure constitutes a single point on the adsorption isotherm. Repeat the above procedure to find other points on the adsorption isotherm. In successive cycles, the pressure within the sample chamber increases, eventually resulting in saturation of the sample solids with condensed N2 at atmospheric pressure. In other words, in the sample and in the free space inside the sample holder, N2
Condensation occurs. According to common practice, approximately eight data points on the adsorption isotherm are generated for surface area measurements.

General K, it takes 1 hour per data point to achieve pressure equilibrium. Therefore, it goes without saying that this method is very time consuming, with two delays per data point to wait for equilibrium, and the adsorption isotherm data points are discontinuous. Occurs at pace.

For details on this method, please refer to “5surface Tecbn
ologyJVol, 4. pp. 121-160 (1975
) Published in Dollimore, D,, 5ponn
er, P., and Turner, A+ paper “T.
he BET Method of Analysis
of Ga5Absorption Data an
d Its Relevance to The Cal
curation of 5surface Areas
It is described in J.

Discontinuous volumetric analytical gas sorption units have been improved by automating the opening and closing of stopcocks and increasing the number of sample chambers and volumetric units.

Furthermore, the time required for equilibration is reduced by determining the equilibration time experimentally and programming the automatic system to respond to the preset equilibration time.

However, this does not change the discontinuous nature of the device's operation and still requires excessively high latencies to obtain relatively few data points.

Bosch and Peppelenbos
rnal of Physics E: 5cient
ific Instruments J Vol.

10, pp. 605-608 (1977), proposes a dynamic method for determining data points on adsorption isotherms.

According to this method, the adsorbed material in the gas phase is loaded at a known volume and temperature at a so-called constant volumetric flow rate (e.g., about 1 crrt3STP m1n-' at a partial pressure of about 0.25) while the pressure is measured. (e.g. liquid nitrogen temperature) into an evacuated sample chamber. The constant volumetric flow rate is achieved by introducing the absorbed agent into the sample chamber via a capillary tube. The amount of adsorbent adsorbed by the adsorbent is calculated from K by comparing the pressure increase in the sample chamber in the presence of the adsorbent sample versus time. It should be noted that in a blank test or blank cycle (i.e., a measurement when no adsorbent sample is present in the sample chamber), the pressure increases as a function of time. If an adsorbent is present, the adsorbed gas will be partially adsorbed and will take longer to reach the pressure than in the blank test. Therefore, the volume of gas or gas adsorbed by the sample (va) at a particular pressure is calculated from the following equation:

(Va = φV (S T P ) Δt) p In the above formula, φV (STP) represents the volumetric flow rate (α'm1n-' ) flowing through the capillary at the standard temperature and pressure, and △t is the value compared with the blank test. is the extra time required to reach pressure P in minutes. Although the volumetric flow rate is treated as constant for a single data point on the adsorption isotherm, in reality, as is also acknowledged on page 608 of the above-mentioned paper, for example with nitrogen as the adsorbent, When used, rather complex calculations are required to generate adsorption isotherms that are not constant and are more partial than SobK.

This method also has other drawbacks due to the use of capillaries to regulate or control the flow rate.

For example, the properties of fixed capillaries change with time and environmental conditions. For example, variations in environmental conditions can cause variations in the flow rate of the adsorbed material as a result of thermal expansion or contraction of the capillary. Furthermore, fixed capillary tubes are not only difficult to manufacture within a specific flow rate range, but also clog with solid adsorbent during desorption, and are brittle in nature, requiring frequent replacement. Also, fixed capillary tubes cannot be adjusted to control the gas flow rate and cannot provide optimal conditions dictated by the type of adsorption sample used. More importantly, even assuming a constant volumetric flow rate, e.g. s o o trt27g
(Durham) is the point at which large errors (eg, 10 to 15% or more) intervene in adsorption isomixing and surface area measurements of materials with very large surface areas. This large error is due to the fact that the larger the surface area of the sample, the longer it takes to reach equilibrium pressure.
Derived from fact. Therefore, for a given weight of sample, the larger the surface area, the lower the flow rate must be, and the lower the flow rate, the smaller the capillary ID (inner diameter). gone,
This makes the flow rate more sensitive to changes in environmental conditions. Even ignoring the environmentally induced fluctuations in flow rates mentioned above, the adsorbent backpressure that develops in the sample holder when approaching higher partial pressures on crosstalks such as adsorption also increases the flow rate. change or decrease. Bosch et al., page 606, acknowledges that even at partial pressures of about 12, backpressure reduces flow by 0.6X. The volumetric flow rate fluctuations caused by such backpressure are even greater when collecting data at high points on the adsorption isotherm. As a result, do we have to accept that the error gradually increases over the entire experimental process?
Alternatively, it is required to compensate for such variations mathematically using highly complex techniques in conjunction with blank tests and sample measurements.

Furthermore, the need to maintain the flow rate of the adsorbed material no greater than the equilibrium adsorption amount (otherwise, from a practical standpoint, it is not possible to obtain a complete adsorption isotherm) makes the use of capillary tubes inherently ineffective. There are restrictions. For example, in a capillary system, the flow rate is proportional to the pressure drop across the capillary K. Therefore, the initial flow rate is so low that the backpressure reduces the flow rate even further, approximately 70 to 5oX of the adsorption isotherm.
After reaching K, the flow rate becomes almost non-existent.

US Pat. No. 2,729,969 to B.
A capillary method very similar to osch' et al. is disclosed. However, the device described in this patent also suffers from the same disadvantages mentioned above due to the use of capillary tubes to control or adjust the flow rate of the adsorbed material. be. The introduction of the adsorbent takes place at a flow rate of about 7 to 10 CCZ in a partial pressure range of about 0.1 to 0.3. As is clear from the description in column 6, line 45 et seq. of the above specification, when a sample with small pores (meaning high surface area) is used,
Even at a flow rate of 10 ccZ min or a flow rate of 7 cc/min, equilibrium pressure conditions did not occur. That is, the flow rate was greater than the equilibrium adsorption amount or rate of the adsorbent. however,
To lower this flow rate, K must use a capillary tube with a smaller diameter, which increases the flow sensitivity to flow fluctuations induced by environmental conditions.
Alternatively, lower pressures can also be used, but then the flow becomes more sensitive to backpressure-induced flow fluctuations. Furthermore, in the fourth column, line 5 and below of the same specification, it is stated that the flow rate is constant as shown in FIG. However, FIG. 4 of this patent specification is only 1
One data point is used to represent only 150 seconds of flow time. Bosch et al. also use a flow time of 60 minutes and six data points to plot a similar curve to support the claim that the flow rate is constant. However, none of this data suggests that the flow rate should be controlled initially for a sample of unknown surface area for a sufficient time to achieve a partial pressure in the monolayer volume range, e.g. There is no evidence that the flow rate is constant over the approximately 4 hour flow time required if one were to maintain below the equilibrium adsorption of . As already mentioned, environmental KN-induced flow fluctuations accumulate over time. Therefore, the data used to justify the constant flow rate claim in the capillary method does not reflect the operating conditions required under which a commercially acceptable device will operate.

Additionally, if the Bosch et al. capillary device were to be used to determine desorption isotherms (discussed below), the fixed leakage capillary method suffers from other serious drawbacks. In desorption experiments, previously adsorbed gas is removed from the surface of the sample via a capillary tube connected to a vacuum source.

In this process, the pressure within the sample holder decreases over time. Therefore, the pressure difference across the capillary tube decreases as a function of time during the course of the desorption experiment. Since the driving force for removing previously adsorbed gas from the sample chamber is due to this pressure difference, even partial desorption experiments require about 2 hours to about 40 hours to complete. Therefore, capillary desorption methods are time consuming, and environmentally induced volumetric flow fluctuations accumulate over long periods such as those mentioned above, and this method allows the actual volumetric flow rate at any given time (and hence for a given Complex arithmetic corrections are required to determine the actual amount of gas desorbed at equilibrium pressure. Note that such errors are not described in the above-mentioned document by Bosch et al. This is because desorption is not a concern in this document.

The InneS US patent discloses the use of a capillary system for desorption. However, the problems associated with evacuating the chamber via capillary tubes, as mentioned above, led the inventor to desorb instead of desorbing at liquid nitrogen temperatures.
At room temperature, the nitrogen adsorbed on the sample is forced to heat up. Moving the sample holder in and out of liquid nitrogen not only complicates the process, but also introduces significant errors in determining the volume of the system at equilibrium at liquid nitrogen temperature, for example. With such a discontinuity, the actual temperature of the sample is caused to deviate from the liquid nitrogen temperature. A 1°C deviation of the actual sample temperature from the liquid nitrogen temperature invalidates the test results.

In summary, in the capillary method disclosed in Bosch et al. and 'Innes, S T P'
less than 1 d/min (at standard temperature and pressure), and this flow rate is substantially constant in the sense defined herein over a given period of time.

Desorption isotherms are important for the following reasons. That is, various mathematical formulas are known that can calculate the pore size distribution of a solid sample from data represented by a desorption isotherm. Here, the desorption isotherm is a plot of the amount of a previously adsorbed gaseous substance (referred to as the desorbent in this specification) that is desorbed from a solid against the equilibrium pressure of the desorbent at a constant temperature. This is the curve. The desorption isotherm differs from the adsorption isotherm in the following points. That is, the former point is particularly sought after starting from a solid saturated with the agent to be desorbed and gradually reducing the pressure applied to the solid in a direction approaching absolute vacuum.

In contrast, an adsorption isotherm starts with an evacuated solid sample and the pressure of the adsorbent in the gas phase in contact with the sample is increased until saturation of the sample occurs. Note that sorption isotherm is used as a superordinate concept of adsorption isotherm and desorption isotherm. In gas-solid interactions, at least a portion of the desorption trajectory of the sorption isotherm is located higher on the isotherm than the adsorption trajectory. This phenomenon in which the desorption trajectory does not follow the adsorption trajectory of the isotherm is generally referred to as hysteresis. The two most common forms of this hysteresis are closed loop and open loop. In closed-loose hysteresis behavior, the desorption trajectory of the isotherm joins the adsorption trajectory at a low relative pressure. Closed-loose hysteresis is usually related to the porosity of the test sample. For example, at the beginning of a desorption isotherm, the pores of the sample are saturated and filled with the desorbed agent. When the desorption process occurs, the desorption of the desorbed agent present in the pores is delayed due to capillary action, so that a lower pressure is required to evacuate the pores compared to the pressure that caused the filling of the pores during adsorption. Pressure is required. This delay is expressed as the closed-loop hysteresis characteristic of the sorption isotherm. Moreover, open-loop hysteresis is caused by the fact that the desorption trajectory of the isotherm line does not intersect with the adsorption trajectory.

Open loop hysteresis is usually related to the amount of measurable irreversible adsorption. Such irreversible adsorption is typically due to the reaction of the gas with the solid sample in sorption, commonly referred to as chemisorption. Therefore, during desorption, less material will be desorbed than was initially adsorbed, thereby creating an open loop in the sorption isotherm.

Note that much can be learned about the surface of a solid sample by intentionally inducing chemisorption. For example, using a gas-phase adsorbent that has a chemisorption effect with the catalyst particles and does not perform chemisorption with the support, the % dispersion and dispersion of catalyst particles with the size of a micro platform placed on the support and Chemisorption can be used to determine surface area.

With other information in the virtually complete sorption isotherm,
The total pore volume, average pore size or diameter, as well as the shape of the pores (eg slit, circular, etc.) can be determined.

The foregoing discussion has discussed in detail 2.5 attempts to obtain a substantially complete curve image of the entire sorption isotherm rather than a narrow segment of the sorption isotherm. As is clear from this discussion, it is believed that a method or apparatus capable of rapidly and accurately generating substantially complete sorption isotherms would have considerable advantages over the capillary methods proposed by Bosch et al. or Innes. It will be done.

Another method for determining adsorption isotherms is [Analyt
ical Chem, J, Vol, 30, page 1
Ne1SOn and Eg published in 5-87 (1958)
Gersten's paper [Adsorption Mea]
Surement By ContinuousFlo
w Method J. In this method, nitrogen is adsorbed by an adsorbent from a gaseous flow of nitrogen and helium at liquid nitrogen temperature, and extracted when the sample is heated. The released nitrogen is measured by thermal conductivity. Therefore, the amount of gas adsorbed is determined not by volumetric measurements at subatmospheric pressures (but by concentration measurements in a continuous flow system at atmospheric pressure).
It is called a chromatographic method for determining adsorption isotherms. This is because it is similar to the Rishi Madography method. Two requirements of this method are that the carrier gas (entraining gas) and the adsorbent gas have a constant flow rate and that these two gases can be mixed in situ. However, in this Ne/sen and other methods as well, the flow rate is controlled by a capillary tube. In contrast, [Analytical Chem,
J, Vol, 45*m 10, page 1307 (
Farey and Tucker's paper [Determination of 5urfa, 1971]
ceAreas By An Improved Co
tiny Flow MethodJ smell C
Attempts have been made to achieve steady flow using a series of pressure and mass flow controllers instead of capillary tubes (
Furthermore, Bhat, R., and Krishnam.
ooorthy, T. [Indian Journal]
alof Technology J Vol, 14
．． 170 (1976)). The nitrogen flow rate suitable for this experiment was 2 to 20 yl/min.

However, as described on page 1609 of the same paper, the flow rate through the detector fluctuates instantaneously due to rapid temperature changes encountered during the adsorption/desorption cycle. Farey
Other chromatography methods do not have this problem.

The reason is that each data point occurs at a discrete pace over a relatively short period of time (e.g. 20 minutes), resulting in discrete peaks,
That is, during the generation of data points, such variations can be compensated for by the mass flow controller. The short duration required for each peak also avoids the accumulation of errors caused by environmental fluctuations over long periods of time. In contrast, the method of the present invention allows for small uncontrolled mass flow during the analytical process (e.g., about 4 hours for adsorption and about 12 hours for desorption), except as noted below. Even possible fluctuations can be eliminated. The invention also takes into account the fact that mass flow rates in the range from 0.2 to α4 ml/min are typically used to achieve this objective. Such low flow rates avoid supplying gas to or desorbing gas from the adsorbent at an amount greater than the equilibrium adsorption or desorption amount, which is typically very low for large surface area materials. This is because it is advantageous. This is due to the fact that in conventional mass flow controllers, the thermal conductivity of the gas through the controller is typically used as the means for metering the gas flow. This problem is further exacerbated by environmental temperature fluctuations that create undesirable and uncontrollable cumulative fluctuations in the flowmeter sensing elements of conventional mass flow controllers.Furthermore,
With the low thermal conductivity of gases at low pressures and low flow rates, environmentally induced variations in flow rate occur and contribute to relative errors in flow rate compared to conventional flow and pressure usage. Conventional mass flow controllers are unsuitable for use in carrying out the method of the present invention; it should be noted that conventional flow meters and thermal valves form the main components of conventional mass flow controllers. ) is US Pat. No. 3,650,505, 5,851,526, 5'95
No. 8384 and No. 4056975.

As is clear from the above discussion, there is a continuing need for faster, cleaner, and more accurate methods and apparatus for determining sorption isolines. The present invention was developed to meet this demand.

SUMMARY OF THE INVENTION According to one aspect of the invention, a method for determining the amount of gaseous adsorbent adsorbed by a solid adsorbent comprises: a) providing an evacuated chamber of known volume and venting gas into the chamber; placing and maintaining a sample of adsorbent at a known temperature; b) applying said sample at a known, substantially constant mass flow rate for a sufficient period of time to effect adsorption of at least a portion of the adsorbed material by said adsorbent; A gaseous adsorbent is introduced into the chamber containing the adsorbent, in which case the mass flow rate is not greater than the equilibrium adsorption amount of the adsorbent by the adsorbent, and is less than about 0.7 R17 min under standard temperature and pressure conditions. It's also big (,
c) establishing an equilibrium pressure of the adsorbent as it is introduced into the chamber as a function of time, the equilibrium pressure being the sampling chamber pressure; and d) setting the sampling chamber pressure of the adsorbent, the sampling chamber pressure The mass flow rate of the adsorbent and the time required to achieve the above sampling chamber pressure,
A method is proposed comprising correlating the amount of adsorbed material adsorbed by the adsorbent at the sampling chamber pressure.

According to another aspect of the invention, a method for determining the amount of desorbent to be desorbed as a gas from a solid desorbent saturated with condensed desorbent comprises: a) pre-outgassed; A sample of a desorbent having a condensed desorbent is housed in a known volume and at a temperature in equilibrium with a chamber atmosphere consisting of a gas phase desorbent.

b) at a known substantially constant rate not greater than the equilibrium desorption amount of desorbent from the desorbing medium for a period at least sufficient to desorb the condensed desorbent from the pores of said sample; C) setting an equilibrium pressure of the desorbent as a function of time as the desorbent is removed from the chamber, the equilibrium pressure being equal to the pressure of the desorbent; d) the sampling chamber pressure of the desorbed agent, the mass flow rate of the desorbed agent, and the time required to achieve said sampling chamber pressure to be desorbed at said sampling chamber pressure; A method is proposed that includes steps that are correlated to the amount of desorbent used.

According to yet another aspect of the invention, an apparatus for determining the amount of gas adsorbed by a solid adsorbent sample or the amount of gas desorbed from a solid desorbent sample, comprising: (1) the solid sample and a chamber; chamber means defining at least one chamber of known and constant volume for containing gas introduced into or removed from the chamber means; (2) continuously introducing gas into said chamber means; or means for continuously removing gas from said chamber means; and (3) controlling the pressure of said gas within said chamber means as a function of time as said gas is introduced into said chamber means or removed from said chamber means. (4) controlling a mass flow rate of said gas being introduced into said chamber or said gas being removed from said chamber such that: (a) said mass flow rate is at least as high as that of said gas in said chamber; be substantially constant over the entire partial pressure range from about 0.02 to about 1.0; and (b) not exceed the equilibrium adsorption amount of the gas by the adsorbent sample during the introduction of said gas. and (5) control means for controlling the amount of gas desorbed from the desorption medium sample to be smaller than the equilibrium desorption amount of the gas from the desorption medium sample while the gas is being taken out from the chamber means; (6) means for maintaining a known temperature of the gas in said chamber substantially constant.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that in FIGS. 2 and 3, elements that a person skilled in the art would consider desirable in actual operation of the apparatus are omitted. This is to simplify the illustration of the invention and to avoid explaining technical details that are already well understood.

It should therefore be noted that such types of equipment as would obviously be required, for example, for power supply, electrical connection of solenoid valves, computer-aided automation, etc., have been omitted from illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the invention is characterized in that it is both dynamic and capacitive. The method can be carried out in an adsorption mode, a desorption mode or a combination of the two modes mentioned above, followed by an adsorption mode and a desorption mode.

Adsorption mode is carried out using gases or substances initially present as gases as well as solids. In this specification, the above gas is referred to as an adsorbed substance or an adsorbent, and the solid is referred to as an adsorbent, an adsorbent, or a sample. During the implementation of the adsorption mode, the adsorbed substance or adsorbent is changed depending on whether the nature of the adsorption is designed and controlled to be physical or to be controlled to be physicochemical. It will be done.

As is known, adsorption phenomena can be the result of physical or chemical processes depending on the system used and the temperature used. Physical adsorption (often referred to as Van der Waals adsorption) is the result of relatively weak interactions between solids and gases. One of the features of this free adsorption is that any gas adsorbed by the solid can be removed by evacuation at approximately the same temperature at which the gas was adsorbed. In chemisorption (in this process physical adsorption also occurs), there is a much stronger interaction between solid and gas than in physical adsorption. Chemisorbed gases cannot be removed from solids by evacuation at approximately the same temperature at which the gas was adsorbed; initial removal of chemisorbed substances requires a temperature considerably higher than the adsorption temperature. Exhaust temperature is required.

Typically, during chemisorption, the adsorbent chemically reacts with the adsorbed substance. Therefore, in the case of physical adsorption, the substance to be adsorbed is selected in relation to the adsorbent such that it is chemically inert towards the adsorbent. Furthermore, since the amount of gas physisorbed at a given pressure increases with decreasing temperature,
The adsorbed material is typically at a temperature of about -195°C.
to about 100°C (e.g. -195°C to 0°C). The adsorbed substances or adsorbents used in the method of the invention are those commonly used in gas sorption capacity analysis methods.

Representative examples of adsorbents conventionally used for physical adsorption include nitrogen, argon, hydrocarbons such as butane, hexene, benzene, H2O and CO2.

Typical examples of adsorbents, referred to herein as chemisorbable substances or chemisorbents, that are commonly used to perform chemisorption include 02 r COr CO2rH20, H
2nd prize is included. The adsorbent or sample is any solid whose morphological characteristics, such as surface area, are to be analyzed. The method described herein typically uses approximately 0.01
from about 1500, preferably from about 0.05 to about 12
00, and more preferably from about α5 to about 8001r
L2/g surface area and typically about 5 to about 5
50 angstroms, preferably about 7 to about 450 angstroms
angstroms and more preferably from about 9 to about 4
It is applicable to samples or specimens with a pore size of 0.00 angstroms. Note that the above pore size range reflects the inherent limit in the Kelvin equation, which will be described later.

Before determining the amount of adsorbed material adsorbed by a sample or specimen, the sample is freed from impurities by removing (i.e., degassing or outgassing) adsorbed atmospheric gases such as nitrogen, oxygen, water vapor, etc. cleansed from This is Orr, C., and Dallavalle,
[Fine Particle Measu] by J.
-rement J, Macmillan Com
This is accomplished by conventional methods, such as those described in Pany, Inc., pp. 164-204 (1960). Note that the disclosure content of this document is incorporated herein for reference. According to this method, degassing is performed by e.g.
The sample is heated in vacuum at a temperature of about 110°C to about 600°C (e.g. 3°C).
00 to 400℃) for about 4 hours.
This is accomplished by heating for a period of time (eg 8 to 12 hours).

The weight, and optionally the density or concentration, of the sample is determined according to conventional methods before contacting the sample with the adsorbed substance.

The device in which the adsorption mode, which will be described in more detail below, is carried out is equipped with a chamber that can be evacuated. For convenience of explanation, this chamber is assumed to be composed of two parts. That is,
A conduit of the device that communicates with the sample holder in an unrestricted manner during the experiment, through which the adsorbed material is passed and introduced into the sample holder. The volume of the chamber is precisely determined in advance according to conventional volumetric analysis methods and the ideal gas law. This volume is preferably corrected for the sample volume based on the sample density by subtracting the sample volume from the chamber volume if a sample is present. However, when using high surface area samples that have a very small volume compared to the volume of the chamber, the volume of the sample can be conveniently ignored.

When using the apparatus of the present invention, the sample holder is hermetically sealed using a stopcock and can be detachably removed from the conduit section of the chamber. Therefore, although it is a matter of convenience, weighing, degassing and evacuation of samples or specimens is
It is usually advantageous to carry out this in a sample holder which has been removed from the chamber and to subsequently connect the sealed and evacuated sample holder to the conduit section of the chamber. According to conventional capacitive gas adsorption analysis methods, the volume of the sample holder is typically selected to be about 10 times to about 200 times the volume of the sample. This accurately determines the reference (blank) for both adsorption and desorption, minimizing errors that can intervene in line capacitance values at the liquid bath-air interface at the liquid nitrogen level and determining the density of the sample. This is to minimize the above error.

The temperature of the adsorbed substance is also known and preferably remains constant throughout the experiment. The temperature of the adsorbent in the sample holder part of the chamber is
The temperature of the sample holder portion of the chamber is typically controlled to be within about ±1° C. of the boiling point of the adsorbent at atmospheric pressure. Therefore, the temperature of the sample holder in the chamber is also determined. This is accomplished by immersing a large portion of the sample holder in a liquid bath of a known, preferably constant temperature. As a matter of convenience, to avoid the use of superatmospheric pressures, the temperature of the liquid bath is typically sufficient to cause condensation of the adsorbent at around atmospheric pressure. do. This means that either the adsorbent is in a liquid phase at atmospheric pressure as a liquid bath to control the temperature of the specimen or sample holder, or that a specially formulated adsorbent boils at a temperature not higher than the boiling point of the adsorbent at atmospheric pressure. This is easily accomplished using liquids. However, in certain instances where the liquid bath is liquefied sorbent, impurities within the liquid bath may cause the temperature of the bath to be slightly higher than the boiling point of the pure liquefied sorbent.

As a result, the saturation pressure of the adsorbent or adsorbed substance (the pressure at which the adsorbed gas is in equilibrium with the liquefied adsorbent) is:
It can be higher than 1 atm. In this case, the adsorbent condenses at nearly atmospheric pressure. The sample holder itself typically consists of two
It consists of two parts. a relatively large volume section containing the sample and a relatively small volume capillary neck. Approximately half of the capillary neck is immersed in the liquid bath and is at bath temperature, while the remainder of the capillary neck (which is at room temperature) becomes part of the conduit section of the chamber when in contact with the device. The temperature of the conduit section of the chamber is maintained constant by maintaining approximately 98X of the chamber conduit volume vc,'r, in a known constant temperature-controlled environment (e.g., approximately 39°C); The adsorbed material within the volume can be equalized to the controlled environmental temperature and therefore also constant. VCoT therefore represents the chamber line volume at constant temperature in a controlled environment. Next, take a pressure reading of the dust adsorbent in the volume vc, 'r. The temperature of the adsorbed material in the volume vc,'r, is the remaining 2X of the chamber pipe volume at room temperature.
It is assumed that the adsorbent is in equilibrium with the adsorbent present in the portion (VH,T,). Therefore, room temperature fluctuations are compensated for and can be ignored. Therefore, the temperature difference between VCoT, and VR,T is sufficiently small, and VCoT,
The volume of T is the total chamber pipe volume (vC8T, +■R,T,
”, and the remaining chamber conduit volume is
It is sufficiently small compared to the total chamber volume, so this temperature difference can be ignored, and the temperature of VC,T, is given by Equation 1
to the temperature (TI, ) of the pipe volume (ML) of 30 chambers.

In this way, an evacuated chamber of known volume is provided containing an outgassed sample and maintained at a known, substantially constant temperature. The chamber is preferably continuously heated, preferably for a period sufficient to achieve a partial pressure of the adsorbed material of at least 0.20 as described below, and even more preferably at least a portion of the adsorbed material in an adsorbed amount. The adsorbent is introduced at a known, substantially constant mass flow rate for a time sufficient to condense (i.e., partial pressure is 1) to The pressure of the adsorbent is set as . This pressure is referred to herein as the sampling chamber pressure.

The term "substantially constant" as used in connection with mass flow rate is used during the entire period of gas introduction and during substantially the entire period of gas withdrawal, when the mass flow rate is 0. 2 rats
If the variation in mass flow rate is not less than 7 minutes, the variation is not greater than ±[1L4X, preferably not greater than ±0.2%, and most preferably greater than ±α15%. and the term ``substantially total gas withdrawal period'' or similar expressions are defined below in relation to the partial pressure range over which gas withdrawal occurs. . The mass flow rate is approximately 0. O5 and about t19WA! The term "substantially constant" is defined as a mass flow rate where there may be no more than about ±1% variation in mass flow rate. Mass flow rates smaller than about αo5 are not used in practice. This is because such low mass flow rates require an economically unacceptable amount of time to complete a measurement cycle. By using a substantially constant mass flow rate, the mass flow rate during the entire period that the adsorbed material is introduced into the chamber can be adjusted to
They can be measured with extremely high precision, hitherto not achievable with conventional methods such as the capillary method of ES and Bosch et al.

The flow rate at which the adsorbent is introduced into the chamber is selected to be no greater than the equilibrium adsorption amount (rate or rate) of the adsorbent on the sample. More specifically, under any combination of volume, temperature, pressure, and amount of adsorbent in contact with the sample, the proportion or amount of molecules of the adsorbent that collide with the sample and are adsorbed is determined by Ultimately, the view of the adsorbent molecules emerging from the surface of the sample is the same. When this situation occurs, the amount or rate of adsorption at that time is referred to as the equilibrium adsorption amount or rate.

At constant volume and temperature conditions, achieving this equilibrium condition requires that the adsorbent pressure remains constant (i.e., does not vary by more than ±0.25%) over a period of, for example, about 20 to 40 minutes. Confirmed by.

When the mass flow rate used in the present invention exceeds the equilibrium adsorption amount or rate, the introduction of adsorbent is interrupted and it takes a finite period of time for the pressure in the chamber to become constant. However, if the adsorbent feed is interrupted when the mass flow rate is not greater than the equilibrium adsorption amount or rate, the pressure will remain constant from the point of interruption. Therefore, by controlling the mass flow rate so that it does not become larger than the equilibrium adsorption amount,
The pressure set at any point during the introduction of the adsorbent is said to be the equilibrium pressure. This is very meaningful. This is because the adsorption isoline is obtained by plotting the amount of adsorbed adsorbent at a given equilibrium pressure. In this way, the adsorption isotherm can be easily determined.

The mass flow rate that can satisfy the equilibrium flow limitation conditions described above is proportional to the weight of the sample. Furthermore, slightly higher mass flow rates could be used for small surface area samples compared to large surface area samples. This is because the equilibrium pressure is established more quickly than in the former case. With this in mind, the mass flow rate at standard temperature and pressure conditions (S, T, P,) for a sample weight of about 0,1 to tOI is not greater than about 17-7 min, preferably α
no greater than 5 d/min and most preferably about 0
．． no more than 4 d/min, typically from about [LO5 to about 0.7 trtl1 min (e.g. 0.05 to 0.1
9), preferably from about α2 to about 0-5rnl1 min, and most preferably from about cL2 to about α4d/min. Since the surface area and porosity of the sample are often unknown, α5g/min, typically α2 or C
A mass flow rate of less than L 4 Ml 7 minutes was found to be adequate for most samples. The flow rate described above is expressed as a mass flow rate because the mass flow controller described below responds to the thermal conductivity of the gas, which is proportional to the mass of the gas. Therefore, millilit kcnl')7min can be converted to mass by the Arrhenius equation.

As mentioned above, the adsorbent is introduced into the chamber for a sufficient period of time to achieve an adsorbent partial pressure of at least about 0.20 for surface area measurements. is preferable. However, if a complete adsorption isotherm is desired, an adsorbent partial pressure of at least CL98 is required. The partial pressure (P/Ps) of the adsorbent is defined as the chamber pressure CP' at any point during the introduction of the adsorbent, for example, when the adsorbent liquefies in the free space of the chamber (room temperature and volume conditions). ) of the adsorbed material, i.e. the saturation pressure (P8)
This is the quotient divided by . This partial pressure is also referred to herein as relative pressure. At adsorbent partial pressures higher than 0.4, Equation 50B, which will be described later, is derived from the adsorption isotherm.
The linearity of the ET curve is gradually lost. Therefore, when using the BFJT equation to determine surface area, typically from about 0 to about α4, preferably from about 0 to about 0.33,
It is particularly preferable to use adsorption isotherm data in the adsorbent partial pressure range of about 0 to about 0.30. However, if other mathematical models are available for determining surface area at higher adsorption partial pressures in the adsorption isotherm, these data could of course also be used. The method described here is a method that allows the amount of adsorbed material to be measured, and therefore the introduction of the adsorbed material is
It is necessary to continue for at least a sufficient period of time for the sample to adsorb at least a portion of the adsorbent.

As stated above, the adsorbent is most preferably introduced into the chamber for a sufficient period of time to allow at least a portion of the adsorbent to condense on the sample. Condensation, which is the liquefaction of the adsorbed material in the free space of the sample holder, should be distinguished from adsorption. Adsorption occurs immediately after contact of the adsorbed material with the sample begins. Condensation, on the other hand, occurs as the chamber atmosphere becomes saturated with adsorbed material in the presence of the sample. Condensation therefore occurs at adsorbent partial pressure (P/P, )=1.

For this reason, the complete adsorption isotherm can finally be determined by continuing to introduce the adsorbed material until condensation occurs.

Therefore, to achieve sufficient adsorption required to achieve a single layer of adsorbent for surface area measurement purposes, the adsorbent is typically larger than about cL1, preferably about 0. greater than .2 and most preferably about CJ
-5 (e.g., greater than f15), and typically from about 0.2 to about α33, preferably about α25
from about α33, and most preferably from α30 to about α3
The adsorbent is introduced into the chamber for a period sufficient to obtain an adsorbent partial pressure within a variation range of 5. In order to obtain a complete adsorption isotherm, the introduction of the adsorbed material is typically approximately 19
Continue for a sufficient period of time to generate a partial pressure greater than 5, preferably greater than about 0.98, and most preferably greater than 1. Generally, at the mass flow rates described herein (which in practice are converted to reflect the temperatures and pressures actually used as described below), the partial pressures as above are: This is typically accomplished with a continuous adsorbent introduction time of about 2 hours to 15 hours, preferably about 3 hours to about 12 hours, and most preferably about 4 hours to 10 hours.

The pressure in the chamber when the adsorbent is introduced is determined, for example, by measuring the equilibrium pressure of the adsorbent as a function of time starting from the beginning of the adsorbent introduction. When operating at a mass flow rate not greater than the equilibrium adsorption capacity, the sampling chamber pressure is equal to the adsorption equilibrium pressure of the adsorbed material. Preferably, the equilibrium pressure of the adsorbent is measured at sufficient times during the introduction of the adsorbent so that an accurate portion or all of the adsorption contour is achieved. Typically, this measurement is made during the introduction of the adsorbent from about 100 to about 10. ODD, preferably about 2
00 to about 2000, and most preferably about 300
to about 600 pressure data points are obtained. If desired, it is also possible to continuously measure the adsorption equilibrium pressure of the adsorbent. However, when the partial pressure of the adsorbent ranges from about 0 to about 0.35, about 4
A pressure sampling frequency of 00 to 600 times was found to be most effective for BET surface area measurements in adsorption mode.

The mass flow rate is not necessarily known during the adsorption of the adsorbent by the sample, but is determined at any time before or after, preferably before, the adsorption cycle of the sample. The easiest way to determine this mass flow rate is to perform a blank test. In this blank test, the adsorbed material is introduced into the chamber in the absence of the sample under the same conditions used when the sample is present, and the equilibrium pressure in the chamber, referred to as the reference pressure, is measured as a function of time. do. In this case, the mass flow rate under standard temperature and pressure conditions can be determined from the following equation.

In the above formula, MFFL is the mass flow rate in the blank test in r/Ll/min, ΔP(fil#) is the change in chamber pressure during period (1), and ■ is the change in chamber pressure at temperature TL. Represents the pipe volume (I3), ■s, H0 is the temperature TS
, H, represents the sample holder volume (crn5),
T represents the chamber pipe temperature (0K) of volume ■L, and T
are the temperatures S, H, S, Ho (0K) of the sample holder with volume V .

Period (1) is typically the period measured from the beginning of the introduction of the adsorbent into the chamber to a time sufficient for the adsorbent to condense within the chamber. However, since the pressure/time relationship in a blank test cycle for calibration is essentially linear at a constant flow rate, time (1) is exactly outside the pressure/time curve up to the pressure at which condensation of the adsorbent occurs. It just needs to be long enough to be inserted.

The mass flow rate in the blank test was
If set using the same mass flow rate to determine the time relationship, the volume of adsorbed adsorbent fJ (Va, 5)
can be calculated at any time point (1) during the introduction of the adsorbent according to the following equation.

--------(Equation 2) In the above equation, P, Vl, , TL, VB, H, and TS, H, are the parameters mentioned in relation to Equation 1, and Pl is represents the change in the sampling chamber pressure during the same period (1), where V'S,H, is the temperature TI
S, H.

represents the sample holder volume corrected to the sample holder volume, where T' S , H, is the volume containing the sample V'
Represents the temperature of the S, H, sample holder. Using a sample holder volume that is very small compared to the chamber volume, thereby making no correction for the sample holder volume necessary and ignoring the period from the beginning of the introduction of the adsorbent, Equation 2 can be rewritten as It will be done.

In the above equation, P is the reference pressure, pl is the sampling chamber pressure after the adsorbent feeding time (1), and the remaining variables are the same as defined in Equation 1.

Other formulas can also be derived, such as those used by Bosch et al. In this case, the difference in time required to reach a particular adsorbent equilibrium pressure in the presence and absence of the sample is used to calculate the amount, eg, volume, of adsorbent adsorbed by the sample. In either case, however, the quantity, e.g. Desired.

Note that for desorption, Pl is greater than P and the difference is marked with a positive sign.

Desorption mode is the opposite of adsorption mode.

In the desorption mode, a solid whose morphological property is to be measured, referred to herein as a desorption medium or sample, as well as a gas or liquid, referred to as a desorbent, may be used.

The desorbent is evaporated from the sample during the desorption mode. Therefore, in the desorption mode, the starting material is first outgassed and its surfaces and pores are in contact with the desorbent so that it condenses, the pores are filled and the external surface of the sample is A sample is used that is covered with at least a single layer of condensed desorbent. Conveniently, the sample is saturated with a desorbent to ensure complete filling of the pores of the sample. The gas that condenses on the sample is called the desorbent. Therefore, the term ``desorbent'' is used instead of ``adsorbent'' simply to identify the mode in which the gas or liquid that constitutes it is used, and constitutes the sorbent and the desorbent. The substances that do are the same.

In carrying out desorption i-de, a sample with the desorbent to be desorbed is placed in a known, preferably chamber having a constant volume and temperature as described in connection with the adsorption mode, and the sample with the desorbed agent condensed therein is exposed to the gas phase. Equilibrate with the room atmosphere consisting of the desorbent. This is typically achieved by running the adsorption mode until saturation of the sample occurs, as described above. The adsorbent is therein preferably continuously, at least for a period sufficient to desorb the condensed desorbent from the sample, and more preferably until the sample is completely free of desorbent. Remove from the chamber at a constant mass flow rate. As used herein, the term "substantially constant" when used in conjunction with desorbent mass flow rate is not less than about 0.02, preferably not less than about 0.03, particularly preferably about 0.0.
It is only valid for desorbent partial pressures (P/Ps') not less than 0.4.

At desorbent pressures less than about 0.02, the mass flow controller cannot maintain the mass flow rate substantially constant.

However, this does not affect the accuracy of the results. and 15 because no usable data can be obtained in the partial pressure range of 0.02 to 0.

The desorbent extraction mass flow rate is controlled (in a manner similar to the mass flow rate during adsorption) so that it is not greater than the equilibrium desorption amount of desorbent from the sample. Equilibrium desorption rate or rate is the same as defined above for equilibrium adsorption rate or rate, except that the equilibrium condition is established under conditions where gas is removed from the chamber rather than being introduced into the chamber. They have the same meaning.

Using such a flow rate simplifies the procedure. This is because the chamber pressure at any point during the removal of the desorbed material is the equilibrium pressure of the desorbed material, and this equilibrium pressure of the desorbed material is the data point on the upper axis when plotting the desorption etc. line. This is because.

S, T with a sample weight of about 0.05 to about tag.

The desorption mass flow rate under P0 conditions is typically about 0.74
not more than 7 minutes, preferably about a s rru37
and more preferably not greater than about 04 lengths/min, and typically about α05 m
l 7 minutes to about 0.7 ml 7 minutes (e.g. 0.05
Na~・shi0.19 and/or 11.2 to o,
7 ml 7 minutes), Kosei Shikke approx. I], 2 to [14
ml 7 minutes, and more preferably about α2 to about 0
．． 3 rnl Varies in the range of 7 minutes.

Slightly higher desorption mass flow rates can be used for samples with low porosity compared to samples with high porosity. The reason is that the equilibrium pressure develops more quickly than in the former case. If the porosity of the sample is unknown, CLs ml
Less than 7 minutes, typically 0.2 to 4rn
A desorption mass flow rate of 7 minutes is suitable for many samples.

As mentioned earlier, the removal of the desorbed agent requires at least the following steps:
This continues for a period sufficient to desorb the condensed desorbent from the pores of the sample. In this connection, the statements made above regarding the difference between condensation and adsorption also apply to the desorption mode. That is, complete desorption of the desorbed agent from the surface of the sample (as distinct from the pores within the sample) need not occur. The reason is that the desorption wire is mainly influenced by the porosity characteristics of the sample. By continuing to take out the desorbent until the condensed desorbent is removed from the sample pore, the pore size or pore diameter is calculated by making an arithmetic correction for the remaining desorbent adsorbed to the hole wall. This provides important information needed to determine the distribution of As a matter of convenience, it is desirable to remove all desorbed agent from the sample.

Desorption of the desorbed agent condensed from the sample typically takes about 1
This occurs when the partial pressure of the desorbed agent (P/Ps) is less than 0. This desorbent partial pressure is used in the same meaning as defined for the adsorbent partial pressure.

Therefore, the desorbed agent is typically about 0.20
less than, preferably less than about 0.10 and most preferably less than about CLO4, and typically from about to to about 0.2, preferably from about 10 to about 0.1
, and particularly preferably about t.

The chamber is removed for a sufficient period of time to obtain a partial pressure of the desorbed agent which can vary within a range of from about 0.02 to about 0.02.

Generally, at the desorbent mass flow rate, which is converted to reflect the actual operating temperature and pressure as described below,
Such partial pressures are desirably achieved over a continuous desorbent removal time of about 8 hours to 20 hours, preferably about 8 hours to about 16 hours, and particularly preferably about 9 hours to about 14 hours. Ru.

As in the adsorption mode, the chamber pressure in the presence of the sample (referred to as the sampling chamber pressure in the desorption mode) is determined as a function of the short time for removal of the desorbed agent. This is achieved, for example, by measuring the equilibrium pressure of the desorbed agent as a function of time as the desorbed agent is removed, starting from the start of the removal of the desorbed agent. Typically, the desorbent equilibrium pressure is measured over a sufficient period of time during desorption of the desorbent to allow a portion, preferably the entirety, of an accurate desorption isotherm to be achieved. In this way, typically
about 500 to about 40,000, preferably about 1,000
from about 10,000, and most preferably about 100
From 0 to about 5000 pressure data points are obtained during desorbent removal over the partial pressure range described above. A pressure sampling frequency of approximately 2000 times was found to be adequate for most samples for typical pore size distribution measurements.

As in the case of adsorption mode, the desorption mass flow rate is determined from the blank test) K, as appropriate, before or after running the desorption mode in the presence of sample.

That is, an empty sample holder is saturated with condensed desorbent and then the desorbent is desorbed at the same desorption mass flow rate and temperature and volume conditions used during desorption mode while measuring the chamber pressure, referred to as the desorption reference pressure. Take it out. Then, the above equation 1
The desorption mass flow rate can be determined according to The pressure/time relationship in the calibration blank test cycle for desorption is linear from the partial pressure point after removal of the desorbed agent condensed on the sample holder wall to a partial pressure of about 0.02. Therefore, the desorbent removal time (time t in Equation 1) is determined for the blank test up to the desorption reference pressure at which the condensed desorbent evaporates from the pores of the sample, and preferably to the desorption sampling chamber pressure at which complete desorption occurs. It only needs to be long enough to allow accurate extrapolation of the pressure/time curve.

Once the desorption mass flow rate has been determined, this mass flow rate is used to determine the desorption sampling chamber pressure 7 time relationship, which is then appropriately substituted according to Equation 2 or Equation 3 above to determine the presence of the sample. By correlating the desorbent equilibrium pressure, the desorbent mass flow rate, and the time required to reach the desorbent equilibrium pressure at any time during desorbent removal (1)
The volume of the desorbed agent (■dsb) can be determined by calculation.

The adsorption line and/or desorption line can be determined from the ads or vdsb obtained by K as described above. For example, in the case of an adsorption isotherm,
and the X axis shows the corresponding relative pressure ds force (P/Ps), (where P is the adsorption equilibrium pressure, P,
is the saturation pressure of the adsorbent at room temperature), and va
d, can be plotted.

On the other hand, in the case of a desorption isotherm, the corresponding desorption equilibrium pressure is used instead of the adsorption equilibrium pressure (P) included in the relative pressure (P/P, ). Using the information embodied in the adsorption isotherm, BE
The surface area of the sample can be determined using the T formula. Also,
Using the information embodied in the desorption isotherm, °C Kelvin (KeL
The pore size distribution can be determined from the formula:
The total pore volume (V) per duram of the sample is determined based on the saturation pressure (vs), the molecular weight (M) of the desorbent, the molecular volume (Mv) of the desorbent, and the density of the liquid phase desorbent, According to Equation 11, it can be calculated from the total volume of adsorbed desorbent per duram of sample at S, T, P, (at standard temperature and pressure).

The BET equation can be used to determine the BET surface value of a substance or material. This BET equation is typically used in the relative pressure range of O to α65 to determine the internal BET surface area of porous materials. The linearized form of the BET formula is as follows.

In the above formula, Pr is the relative pressure (P/
P, ), and ■ is 1 g of sample at relative pressure Pr
is the volume of the adsorbent adsorbed at S, T, P, and Vm represents the monolayer capacity of the adsorbent, that is, the volume of the adsorbent adsorbed as a single layer on the sample; C is the BET constant that depends on the adsorption enthalpy.

A straight line can be obtained by plotting the left side of Equation 4 against Pr. The slope and Y-intercept of this line vm can be calculated from the following equation.

V = −+ , −−−−−−−−(Equation 5
)% Formula % Therefore, the BET specific surface area (SABET) can be calculated from the following formula.

In the above formula, Vm is the one described by Equation 4, Nav is Avogatro's number, 5m01 is the cross-sectional area of the adsorbent molecule, and VrrIol is the cross-sectional area of the adsorbent molecule at S, T, P. where 'mol is the adsorbent molar gas volume in S, T, P, and W is the weight of the sample.

Assuming that the adsorbent molecules in the monolayer are packed in a hexagonal shape, the cross-sectional area of the adsorbed molecules (Smol) can be calculated from the following equation.

Smol = 1.091 CM/Nav) D]21
5--(Formula 7) where M is the molecular weight of the adsorbent, Nav is the previously defined quantity, and D is the density of the adsorbent.

The Kelvin equation is used to calculate the pore size distribution of porous materials. According to this equation, as shown below,
As a function of the ratio of pore volume to surface area per duram,
The vapor pressure for the liquid contained within one pore (or capillary) is obtained.

In the above formula, ■L is the molar volume of the liquid phase desorbent in S, T, P, σL is the surface tension of the desorbent in the liquid phase, R is the gas constant, T is the absolute temperature of the desorbent, Pr is the relative pressure of the desorbent, and φ is the contact angle between the liquid phase desorbent and the pore wall.

Assuming that all holes are circular and do not intersect, the following replacement is possible.

1 = 1/2 Rk-- (Formula 9) In the above formula,
Rk is the Kelvin pore radius of the sample.

As will be apparent to those skilled in the art, other substitutions may be necessary for different pores. Here, it is assumed that the liquid phase desorbent wets the entire bottom surface within the hole. That is, φ=0 and cosφ=
Assume that it is 1. This assumption is favorable for desorption from porous materials.

Therefore, equation 8 can be rewritten as equation 5 below.

In order to calculate the pore size distribution, the volume of the desorbed agent (■dsb) desorbed at a specific pressure interval is determined from the desorption profile. The radius of the hole through which the desorbed material desorbs during this pressure section is:
From the Kelvin equation, the amount of the desorbent that remains adsorbed on the wall of the hole having a thickness t') is calculated by correcting Rk according to the formula ~=~+tl. Here T.I.
is determined from the Halsey equation. By dividing the volume of the desorbed agent by the difference in pore radius, the frequency in the pore size distribution curve can be obtained from K.

Use the value of Δ■dsb/ΔR9 as the Y axis, and
By plotting the distribution of pore size, or radius (S), with the corresponding value of Rp in Angstroms on the axis and integrating the area under each peak in the plotted curve, the Determine the volume of the hole at a specific radius Rp. Regarding the Rk correction for the amount of liquid phase desorbent adsorbed on the wall of the empty hole, N, Y, A
Adsorption, 5urfac by Gregg and Sing, published by cademie Press.
eArea, and Porosity.

The pore volume per duram of the sample is obtained from the following formula.

In the above formula, the variable is a previously defined quantity.

It should be understood that the present invention is not limited to particular mathematical models for using the information embodied in adsorption or desorption isotherms. This information can be manipulated as desired according to conventional procedures or techniques.

The method and apparatus according to the invention can also be used to perform chemisorption. This chemisorption is useful for the following reasons. That is, the surface and/or dispersion of very small particles (such as particles with catalytic activity) can be determined. In this specification, such particles are referred to as a chemical sorbent or an active phase. This particle is deposited on a larger particle, such as a catalyst support, and is referred to herein as a support solid.

Dispersion of the active phase is very useful in catalyst evaluation. The reason is that information is obtained regarding the number of catalytic regions located on the surface of the support.

This field of analytical chemistry has undergone considerable development, and the appropriate selection of chemical sorbents and sorption temperatures for use with particular active phases is discussed, for example, in J. Rev.
Pure Appl, Chem, J Vol, 19
, p. 151 (1969), "AICHESymp, 5eries J, Va.
l+143. F on pages 143, 709-22 (1970)
arranto, rL, in the paper.

The contents of these papers are also incorporated in the present invention; An Hata for reference. The active phase that can be effectively obtained by chemical sorption method includes Pt.

Includes Pd, Ni, Co, Cu, Ag and Fe as well as Cr205*CuO, NiO, sulfides, etc. For example, when the catalyst is platinum, a suitable chemical sorbent is hydrogen, which reacts with the platinum at temperatures above about 0°C. Therefore, the temperature of the chemisorption sample holder is controlled to be at least the above temperature.

Chemisorption mode is a chemical sorption mode in which a suitable chemical sorbent is selectively chemically sorbed onto the surface of the active phase rather than on the solid support. This is done by choosing to do so. If it is desired to determine the dispersion of the active phase, the weight percentage of the active layer deposited on the support must be varied. The adsorption mode is carried out as described herein using a chemical sorbent as the adsorbent and a solid supported active phase as the sample.

The temperature of the chamber is suitably selected in conjunction with the K, chemisorbent-active phase reaction threshold to ensure chemisorption. Upon completion of the adsorption cycle, determine the panorama of physically and chemically adsorbed chemical sorbents as a function of time. During this adsorption cycle, the chemical sorbent is physically and irreversibly chemically sorbed to the extent that it no longer desorbs from the surface of the active phase when the chamber is substantially evacuated. is also sorbed. In contrast, the chemical sorbent is only physically adsorbed by the supporting solid, and complete desorption of the chemical sorbent from the solid support occurs during subsequent evacuation.

In addition, chemical sorption by the active phase in the first adsorption cycle limits the reactive region of the active phase such that it becomes chemically inert upon contact with the chemically sorbed agent following said evacuation. Effectively inactivate.

Upon completion of the first adsorption cycle, the chamber is typically rapidly evacuated to desorb the desorbable chemical sorbent. During this evacuation, there is no need to take pressure measurements and the evacuation speed is chosen to be done as quickly as possible to save time. Upon completion of evacuation, the adsorption mode is preferably repeated immediately for a second cycle, typically using the same chemical sorbent at the same room temperature and mass flow rate as used in the first adsorption cycle.

During the second adsorption cycle, only physical adsorption by the sample takes place, and adsorption of the chemical sorbent that took place during the first adsorption cycle is reduced. This amount is determined as a function of time, and the difference in the amount of chemical sorbent adsorbed in the first and second adsorption cycles is determined for the same period of time. This difference is the amount of chemisorbent chemisorbed by the active phase.

Therefore, the % dispersion of the active phase on the solid support can be determined according to the following equation.

% Active Phase Dispersion=BX100 where A is the number of atoms of the chemisorbent chemisorbed by the active phase and B is the number of atoms of the active phase on the solid support. The person's value is found from the above difference amount, and B
is determined from the weight percent of the active phase on the supporting solid. % active phase dispersion, plus the surface area of the active phase leaves the chemical sorbent irreversibly chemisorbed with the corresponding molecules of the chemical sorbent (
Alternatively, it can also be determined by converting it into an atomic number. The total surface area of the active phase is then determined from the known relationship between the number of chemisorbed agent molecules (M molecules) chemisorbed per metal atom of the active phase and the area of each active phase metal atom.

A preferred embodiment of the apparatus used to carry out the method of the invention will now be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of the preferred elements that make up the device. These elements include a gas or a gas supply which serves as a source of the adsorbed or desorbed agent, and a pressure that does not exceed 1Q-5 vm q, preferably not more than 1 cr7rtra) LSI, and particularly preferably A vacuum or exhaust section that can be evacuated to a pressure not exceeding 10-9 ■Hg and a mass flow rate of the gas being adsorbed or the gas being desorbed are provided for the adsorbent and desorbent described below. A flow control unit equipped with a mass flow controller (controller) that can control the pressure to a constant value (described later), and typically approximately ± of the true pressure value.
a pressure sensing/recording section capable of measuring and recording the pressure of the adsorbent or desorbent with an accuracy of within 0.05 mHp;
an adsorption or desorption section that is equipped with a chamber that allows the introduction of the sample and the adsorbed agent or the desorbed agent into or removal from the sample holder, and also enables volume and temperature control as described in 5 below; , and an outgassing section using the vacuum or evacuation section described above to assist in outgassing the sample.

FIG. 2 shows a simplified diagram of the configuration of each of the above-mentioned parts of the device. Specifically, the gas supply typically comprises one or more gas cylinders 101-104 containing various different gases or gases for adsorption or chemisorption. Each gas cylinder is
Each is connected to line 211 by a conventional exhaust solenoid valve (ASCOTM) 7 to 101C. These valves are actuated at appropriate times in response to signals from computer 117 to direct gas or gases from K to line 2.
It is preferable that the liquid be configured to flow into 11. Line 211 is connected to a mass flow control via lines 201 and 200 with exhaust solenoid valve 5. ,
While introducing the gas or gases into the sample holder 109,
The exhaust solenoid valve 6 is closed and the gas flows through the pipe 21.
1 through open valve 3 and lines 200 and 201 into the mass flow control.

The mass flow control portion of the device includes a mass flow controller or controller. This mass flow controller is an electronic device that operates on the principle of using an adjustable aperture.

The mass flow controller is preset to deliver gas into line 202 at a particular substantially constant mass flow rate, such as the flow rate used in a calibration operation. However, due to the fact that the gas passing through this mass flow controller is the gas that is being introduced into or removed from the sample holder 109, there is a positive back pressure within the sample holder (during adsorption). )
Or a negative backpressure (during desorption) is generated, which causes the mass flow rate to decrease relative to the preset value.

The mass flow controller continuously detects the actual flow rate with a flow meter, compares it with the preset value, and if there is a deviation from the mass reset value, opens or closes the opening or aperture and sets the preset flow rate again. Compensate by increasing or decreasing the flow rate until the

In addition to variations in flow rate caused by variations in pressure within the sample holder, there are other factors that must be controlled to achieve a substantially constant mass flow rate, as discussed below.

For example, in order to successfully use a mass flow controller in adsorption and chemisorption modes, the gas supply to the flow controller should be maintained at a substantially constant pressure.

This is because mass flow controllers of this type tend to compensate for changes or fluctuations in inlet gas pressure relatively slowly. Here, the term "substantially constant pressure" means that when there is a deviation or deviation in the pressure of the gas flowing into the mass flow controller, the deviation is approximately 0. 55 psi is preferably defined to mean a deviation of about ±0.30 psi, and particularly preferably no more than ±0.20 psi. Pressure fluctuations are further reduced by using narrow tubing in the manifold, as discussed below. When in adsorption mode, the adsorbent pressure supplied to the mass flow controller is typically about 1
5 to about 25 psig.

Preferably it is controlled at about 16 to 18 psig.

More importantly, flowmeters successfully used in conventional mass flow controllers require heat to be transferred to or extracted from the flowing gas;
and is based on the principle that the temperature differences induced at different points in the gas flow due to variations in the gas flow rate are used to cause variations in the conductivity of the sensor that are proportional to the changes or fluctuations in the gas flow rate. The point is that it works. The fluctuation in the temperature of the gas as it enters the flow meter is
In particular, it has been found that when operating under the conditions described below at a mass flow rate of 153 degrees for each unit °C variation in the temperature of the adsorbent, errors or errors may occur in the heat detection mechanism of such a flowmeter. are doing. This error or difference accumulates over a long period of time to the extent that it significantly affects the accuracy of the flow rate to be determined. In addition, long-term fluctuations in the ambient temperature (e.g., room temperature) used in adsorption and desorption (described later) may also cause the mass flow rate to vary from the preset value of the flow rate due to disturbances in the thermal response sensing mechanism of the flow meter and the electronic circuit of the flow controller. It has also been found that this results in a fairly large cumulative error. The combination of errors described above makes it impossible to achieve a substantially constant mass flow rate using conventional mass flow controllers under all conditions under which the method of the present invention is practiced.

Accordingly, a mass flow controller is disclosed that can achieve a substantially constant mass flow rate.

A preferred embodiment of this mass flow controller is shown collectively in FIGS. 3 and 4. FIG. 2 also illustrates the incorporation or integration of a mass flow controller 5010 into the apparatus of the present invention.

Referring to FIG. 3, the components of the mass flow controller, except for the pressure control device or controller 311, are housed in a temperature controlled box or box 119. This box or box has an internal space 608
This interior space is in fluid communication with the atmosphere via a vent 601 outside the box and is therefore typically filled with air. The box is typically made from a sturdy material such as sheet material and typically has a volume of about 2500 cc.

The temperature of the atmosphere within the box is preferably maintained above the ambient room temperature in order to allow active control of the box temperature and thereby maintain it constant.

Typically, this temperature is set to avoid damage to the electronic systems contained within the box and to provide a sufficient temperature gradient between the atmosphere inside the box and the atmosphere outside the box so that it is less than K from outside the box into the room. approximately 35°C and 45°C so that a dynamic temperature equilibrium is achieved within the box when air is drawn into the box by fan 407.
(e.g. 39° G). Therefore, it is advantageous for the box temperature selected to be above the temperature that the box would reach due to the heat emitted by the mass flow controller electronics in the absence of another heat source. Thus, air from the environment outside the box is mixed with the air inside the box and heated, and the temperature equilibrium achieved within the box is not disturbed by the mass flow controller electronics.

The temperature inside the box is controlled by the flow controller block 4030.
This is accomplished by a combination of a base-mounted thermistor 404, a proportional-integral-derivative (hereinafter referred to as PID) controller 405, a heating strip 406, and a fan 407. The thermistor 404 detects the air temperature within the destination over a temperature range of 100° C. and generates an electrical signal proportional to the temperature, which is sent to the PID controller 4.
05. The PID controller (RFL model 70A) is preset to generate an electrical signal proportional to the difference between the preset box temperature and the actual box temperature.

An electrical signal generated by a PID controller energizes a heating strip 406 (eg of resistive type 300W capacity). Therefore, the heating source from the PID controller
The magnitude of the electrical signal given to the IJ knob gradually weakens as the actual box temperature approaches the preset temperature.
The signal then becomes substantially constant when the actual box temperature equals the preset temperature, compensating for heat losses to the environment. In this way extremely accurate temperature control is achieved. Fan 407 operates continuously during operation of the mass flow controller to heat the air within the box at a high flow rate of about 10 to 100 times (eg, 10 to 75 times) the box volume per minute or higher. Circulate around the strip. Fan 407 is preferably placed near vent 601 to draw fresh air into box 119.

The temperature control in box 119 serves at least four important functions. (ii) By heating the incoming gas in line 201 and by the time it reaches the sensing coil 411 of the flow meter, the gas is at a constant temperature that is the same as the temperature of box 119, regardless of room temperature fluctuations. (2) Compensate for the temperature sensing of electronic circuitry provided on circuit board 401, thermally responsive valve 302, and pressure transducer or transducer 108 (described below);

(3) It is ensured that the temperature of the gas in the line 210 is constant at the point measured by the pressure quadrant juicer 108. (4) As shown in FIG. 2, the influence of ambient temperature changes on the gas in the chamber conduit space contained within the box 119 is eliminated. If such temperature control were not provided, this variation could cause errors in the pressure measurements of the gas in these lines. Functions (1) and (3) above
To assist in realizing this, conduit 201 is adapted to form coil 213 and conduit 210 is adapted to form coil 212. The volume of the coil (i.e. the internal passage volume of the coil) is α5 for coil 213 and αB for coil 212.
cc is appropriate, and in this way temperature equilibrium between the gas in the coil and the box temperature can be achieved.

The mass flow controller itself is shown in block 301 in FIG.
It is shown in The inlet of the mass flow controller 601 is connected to the conduit 2011C.

Conduit 201 includes a pressure controller 311 (SERTATM) in series with the mass flow controller for the purpose of maintaining a substantially constant pressure of gas entering the controller.
model 204) is provided.

The outlet of the mass flow controller is connected to line 202. Mass flow controller 601 is shown in more detail in FIGS. 3 and 4.

Referring to FIG. 3, the primary side elements of the mass flow controller include the following: That is, (A) detection conduit 2
01a, a sensing coil 411, and a controllable aperture or opening of a thermally responsive valve 302 disposed downstream of the sensing coil 411, for connecting the sensing conduit 201a with the thermally responsive valve 602. a circuit with a stainless steel block 403 extending the entire length; (B) flow controller electronics including a detection bridge circuit 408, a linearization circuit 409, an amplifier 410, and a comparison controller circuit 600; and (C) a heat-responsive valve or thermal valve 302.

Note that the pressure controller 311, although necessary, is a supplementary element to the mass flow controller.

The gas is introduced into and taken out from the detection conduit 201a by
via conduits 201 and 202, respectively. Sensing conduit 201a begins at the block 4030 inlet and is connected to sensing coil 411 (shown as a single coil in FIG. 2, but specifically comprised of two separate coils as shown in FIG. 3). and is connected to the inlet portion of the thermally responsive valve 302. Thermal response valve or thermal valve 3
The outlet part of 02 is connected to conduit 202 via which gas can leave block 403. The thermal valve body and electronic circuitry are screwed onto the top of block 403 and housed in plastic housing 412.
enclosed within.

A preferred thermally responsive or thermal valve is Tey1an
Corporation, and is described in detail in US Pat. No. 3,650,505. The disclosure content of this US patent is incorporated herein by reference.

The circuit board 401 is enclosed within a plastic shell 402.

Next, the circuit characteristics and operation of the mass flow controller are explained in the fourth section.
This will be explained with reference to the drawings. Shown within the block indicated by dashed line 516 in FIG. 4 is the flow meter portion of the flow controller, which includes a bridge circuit 517 coupled to sensing conduit 201a. The bridge circuit is of conventional design and includes a first bridge resistor 501 and a second bridge resistor 50.
It is formed from 2. Further, the bridge circuit includes an upstream sensor element 411a and a downstream sensor element 411b. Sensor elements 411a and 411b are wrapped around sensing conduit 201a adjacent to each other, with upstream sensor element 411a approaching inlet end 518 of conduit 201a and downstream sensor element 411b of conduit 202. It is located close to the outlet end 519.

Bridge circuit 517 also connects DC power supply and converter 50
6 (this circuit operates with an ACt source 507). One side of the bridge circuit is connected via a line 604 to the connection point of sensor elements 411a and 411b, and the other side of the power supply is connected via a switch 505 to a bridge resistor 5.
It is connected to the connection point between 01 and 502. The output signal from the bridge circuit is provided to a first output terminal 503 and a second output terminal 504. The first output terminal 503 is
Upstream sensor element 411a and first bridge resistor 5
01, and the second output terminal 50
4 is connected to the connection point between the downstream sensor element 411b and the second bridge resistor 502. Upstream sensor element 411a and downstream sensor element 411b are formed from temperature sensitive resistance wire wrapped around the outer diameter of conduit 201a. As such a resistance wire, for example, B, alco (Wilbur-Driver Co
It can be an iron-nickel alloy, such as a product manufactured by Mpany.

The circuit design described above is conventional with the following exceptions.

That is, the inner diameter of the sensing lead 11201a is typically about 0.
．． 2mm, preferably 0.05fi and most preferably not more than about 10,2mm, and about 0.005 to about c1.211m, preferably about 001 to about 01 cod, and most preferably about α01 to 0,05n It may be of conventional design, except that it is of capillary size within the range of , thereby achieving a substantially constant flow rate.

Furthermore, since the flow rate processed by the flow meter is a low pressure flow rate, the bypass line typically used in this type of mass flow meter should be omitted. Furthermore, if the inner diameter of the detection conduit 20ja is made excessively large, the density of the gas inside the tube in the pressure can and flow g described in this specification will decrease,
It has been found that this reduces the thermal conductivity of the gas and disturbs the thermal sensing mechanism (described below) of the flow meter, so that a substantially constant flow rate is not achieved.

The combined bridge circuit output signals 505 and “504
is connected to the linearization circuit 409. This linearization circuit 4
09 electronically generates a linear output voltage as a function of mass flow rate. This voltage is applied to the comparison controller 600 via amplifiers 4 and 10. Note that the linearization circuit, amplifier, and comparison controller circuit are all conventional.

In operation, when the switch 505 is closed, current flows through the sensor elements 411a and 411b, which generate heat, so that the tube 20 adjacent to the sensor element
The temperature of 1a increases. In addition, these sensor elements 411a
> and 411b, their resistance values also increase.

When the fluid flow rate in conduit 201a is zero, K, the temperatures of sensor elements 411a and 411b are equal to each other, the bridge is in equilibrium, and terminals 503 and 504
A zero output voltage occurs between them. When fluid enters input end 518 of tube 201a, elements 411a and 411b
) C is carried downstream by the fluid toward the outlet end 519 of tube 201a. Therefore, a temperature difference occurs between elements 411a and 411b due to the transition of the temperature profile along the tube 2o1aK. tube 20
As the fluid flow rate in 1a increases, the upstream element 4
The temperature of 11a and its resistance decrease, while at the same time the temperature of downstream element 411b and its resistance increase. Therefore, the bridge output voltage between terminals 503 and 504 increases approximately linearly with flow rate. After linearization and amplification of the bridge output voltage appearing at terminals 503 and 504, amplifier 410 generates a linear voltage that corresponds to the absolute value of the gas mass flow rate before the gas reaches thermal valve 302. The voltage from amplifier 410 is applied to comparison controller circuit 600 where it is compared to a command signal source as well as an external electrical command signal 514 from selector 520, which is preset to correspond to the selected mass flow rate. The comparison controller circuit is
Any difference between the command signal voltage and the amplifier output voltage generates a difference output signal that is used to energize actuator 502a of thermal valve 602 via line 603. The thermal valve actuator controlled in this way is the comparison control circuit 6o.

indicates that the mass flow rate is insufficient to balance the command signal, the thermal valve is opened, and vice versa, the thermal valve is closed.

When a command signal is selected using selector 520, selector 520 also sends a digital signal via line 132 to computer 117 in FIG. This digital signal is representative of the flow rate selected and calibrated with a previously performed blank test cycle.

In yet another preferred embodiment, sensor element 411
a and 411b are K as disclosed in U.S. Pat. No. 3,938,384.

Can be combined into a single coil with a center tap. The disclosure content of the above-mentioned US patent specification is incorporated herein by reference. Instead of two separate sensor elements, by using a single coil with a center tap, the coils can be closely spaced, thereby reducing heat loss and increasing the distance between upstream and downstream sensor elements. Equalization becomes easier and the gain of the circuit (temperature change per unit flow rate) becomes larger. Additionally, the response of the circuit is faster and the useful flow measurement range as well as the linearity of the circuit is increased.

As an optional feature of the circuit shown in FIG. 4, a voltmeter 510 can be provided between the coupled output terminals 503 and 504. The electrical signal from this voltmeter is sent to a converter (
(not shown) from analog form to a digital BCD signal, which is then sent via line 306 to computer 117 in FIG. During the calibration reservoir blank test cycle, the computer
Sample the output from voltmeter 510 over a period of 0 minutes.

During this period, the computer acquires data at a rate of one data point per second, averages the acquired data, and stores the resulting data as calibrated values in the database. During adsorption and desorption operations, the computer compares the calibration values with the actual values sampled from the voltmeter to determine whether the operations are occurring reliably. This operation is a quality control function that allows deviations from the desired flow rate to be read after the operation is completed.

Although mass flow controllers have been described above in connection with particular flow meters, for example, U.S. Pat. No. 3,650,151
It is to be understood that other types of flowmeters that generate electromagnetic signal versus flow functions may be used, such as those described in US Pat. Although it is preferred to adjust the flow rate with a thermal or thermoresponsive valve as described above, the ability and sensitivity to provide substantially constant flow control under the conditions of use described herein is limited. Other electrically actuated means can also be used. The same is true for the mass flow controller itself. The practice of the present invention requires the ability to achieve substantially constant flow rates over extended periods of time and throughout a range of low flow and pressure conditions as described herein. . We believe that we are the first to develop a device with such capabilities; however, the method and apparatus of the present invention address the necessary requirements for mass flow controllers and associated environmental control boxes that may be developed in the future. This does not preclude the use of other means capable of performing the function.

Referring again to FIG. 2, gas flows through conduit 201 located within environmental control box 119.

passes through coil 213, where the temperature of the gas is box 11.
9 and then the flow controller 30
1, where the flow rate of the gas is regulated as described above to connect lines 208, 209, exhaust solenoid valves 4 and 5.
It also flows into the sample holder 109 of the sample holder section via the stop cock 19.

The sample holder section includes a sample holder 109 and a liquid temperature container 0.
and liquid level controller (control device) 115.20
and a liquid bath 112. The sample holder 109 is typically a glass flask with a volume of 20 mm and a capillary neck 122 made of glass with an inner diameter of about 2 elbows. Capillary neck 122 terminates in a ground glass joint 123 adapted to receive a polished male glass fitting or joint 124 of conduit 125 . Sample holder 10゛9
A ground glass joint 12 is used to add or remove a specimen or sample 110 from the holder.
3 and 124 are separated.

An assembly (hereinafter referred to as assembly A) including a glass joint 124, a conduit 123 connected to the stop cock 19, a conduit 126 connected to the stop cock 19, and a ground glass joint 127 of the IC3'J series is is used, for example, to seal and/or connect the sample holder 109 at the point of the glass joint 21 to the gas release section or the mass flow controller section to the end of the conduit 209 using, for example, the glass joint 128. For example, the Assemblage IJA makes it possible to seal the sample holder with the sample by closing the stop cock 19 after gas release and evacuation. In this way, assembly A and sample holder 109
09 can be sealed and moved to a desired location within the device.

Liquid bath container 0. is typically a dewar flask capable of holding a liquid bath, such as liquid nitrogen, which, when connected to a mass flow control, controls the immersion of the sample holder 119. It is of sufficient size to allow for. As previously mentioned, the liquid bath 112 is typically the liquid to be adsorbed or desorbed, and the level 129 of the bath 112 is at the liquid bath vessel 0.5 during adsorption or desorption. The liquid bath 112 serves to control the temperature of the immersed sample holder 109 when maintained constant within the sample holder 109 .

Also, the level 129 of the bath 112 relative to the immersion depth of the sample holder 109 defines the volume of the sample holder VS, )l in equations 1.2 and 3, while the temperature of the bath 112 defines the temperature FgTs in these equations. , H, and (or)
Define Tls and Ho. For example, container 0. is container 1
12 is filled with sufficient bath 112 such that bath level 129 within sample holder 1090 capillary 122 intersects sample holder 1090 capillary 122 at point 130 in capillary neck 122 described above. The location of point 130 is typically midway between ground glass joint 123 and the end of the capillary neck of sample holder 109 at point 132. Inside the container 11゛1,
A sample holder rack 131 is provided to stabilize the sample holder and ensure that the sample holder 109 is immersed to the same depth in the bath 112 during each operation when the bath level 129 is constant. . Therefore, VS,
Hl is sample holder 109 immersed in bath 112
is equal to the sum of the volume of the capillary neck from points 150 to 132 of the sample holder 109 + the volume of the remaining non-capillary portion.

Container 0. The level 129 of the bath 112 within the Hungton Electron is shown collectively as the control valve 20 and bath level sensor 113 actuated by the sensor 113 adapted for use in this example.
It is maintained constant using a conventional liquid level control device such as the Model 200 manufactured by Nics Inc0. For example, when using liquid nitrogen as the liquid bath, liquid nitrogen tends to evaporate during the course of the experiment. Therefore, additional liquid nitrogen must be replenished to maintain the bath level substantially constant. For this purpose the bath level sensor 11
3 detects a change in bath level and activates control valve 20, causing new liquid nitrogen to flow into lines 308 and 311C. However, this liquid nitrogen
When entering the liquid nitrogen, the temperature in the line becomes higher than the liquid nitrogen, which causes the nitrogen to evaporate explosively. therefore,
Liquid nitrogen and vaporized nitrogen are typically violently released into the liquid bath 112, thereby causing bath level 1.
29 is disturbed. This results in errors or errors in the pressure recorded as a function of time. This problem is caused by a vent or vent line 50 that separates fresh bath vapor from fresh bath liquid before the fresh bath liquid enters the liquid bath container.
It has been found that the problem can be effectively and completely solved by providing 9. According to this method, the bath level is about ±[15a
When the liquid bath 112 evaporates within a deviation of m, the control valve 20
Fresh liquid is received from line 107 which is connected to the liquid bath source (not shown). Bath liquid flows from control valve 20 through line 308 to line 310. The open end of the pipe line 310 is connected to the liquid bath 1
It is immersed in 12. Line 309 defines a vent that opens to the atmosphere and is in fluid communication with lines 308 and 310. The end of line 310 is plugged with a glass coolant, which creates a back pressure and allows the vaporized liquid to flow out through vent line 309 instead of being violently discharged into liquid bath 112. do. K like this,
Drastic fluctuations in bath level 129 are avoided and the bath level remains substantially constant. By keeping the bath level 129 substantially constant, the volume at temperature "S, Hl" is also kept substantially constant.

S,H.

In this way, in order to control the temperature of the indoor pipe space, one
19 and in combination with a liquid bath to control the temperature of the sample holder chamber, the entire chamber volume and the gas or gases contained therein are maintained at a substantially constant temperature. Ru. The term "substantially constant temperature," as used herein with respect to the total room volume, means that the possible deviation in the average temperature of the total room volume typically does not exceed ±0.35X of the average temperature value; Preferably [means not exceeding 120X and more preferably not exceeding 117X].

The primary components of the pressure sensing and recording portion of the device include a pressure transducer or transducer 1108 (SETR
AT 204 3[]OA) and computer 11
7 (Apple IITM) and/or IJ tube paper recording device 118
is included. Pressure transducer 108 is disposed within environmental control box 119 and its inlet end is connected to line 208 (located between exhaust solenoid valves 4 and 5) via line 210 and coil 212. and coil 2
12 is also provided as a button within the environment control box 119. Conduit 20
8 is placed in fluid communication with the adsorption and desorption live sample holder. Within the coil 212, the gas in the line 210 is transferred to the box 11.
is heated to an equilibrium temperature of 9. Accordingly, the amount of gas flowing through line 20 flows through line 210 and coil 212 and contacts the inlet end of pressure transducer 108. coil 2
The temperature of the gas in the sample holder 109, ie, the temperature of the box, is therefore constant, and a change in pressure in the conduit 210 reliably results in a change in pressure in the sample holder 109. Pressure transducer 108 senses the pressure in conduit 210 at a constant temperature and converts the sensed pressure into an electrical signal that is interconnected from the output of pressure transducer 108 via line 304. It is applied to the input end of the active A/D converter 121 (Sodel Aoos-4). This A/D converter 121 converts the analog electrical signal from the pressure transducer 10 into a digital electrical signal. This digital signal is sent to the A/D converter 121
is supplied to the digital computer 117 via a line 306 from its output end.

The analog output signal from pressure transducer 108 is routed to line 3 as appropriate.
05 to the IJ paper recorder 118.

Computer 117 and strip paper recorder 118
are alternative means for recording the pressure of gas being introduced into or removed from the sample holder 109 as a function of time, each of which can be used alone or in combination. You can also do it.

However, the use of a computer is preferred.

In the suction mode, the computer 117 is programmed to perform the following operations.

(a) recording digital pressure signals received directly from the pressure transducer or transducer 108 as a function of time, typically on a quasi-continuous basis, to establish and store a first database of pressure versus time; (b) (C) determining and storing a second database of mass flow rates selected by the computer operator among several different mass flow rates; (C) pressure versus time information of the first database and the selected mass flow rate of the second database; (d) converting the mass flow rate into a third database of all adsorption isotherms, i.e. vad5 pairs (P/P, ) or a portion thereof; and (d) storing said third database. This involves calculating the surface area of the sample from the information in the database using, for example, the BET formula.

In the desorption mode, during desorption operation, the computer 117 is programmed to determine and store the first and second databases described above in connection with the adsorption mode. The computer then determines and stores a third database of desorption isotherms, Vd5b pairs (P/P, ), and uses this third database to determine the pore size distribution of the sample, such as by using the Kelvin equation. Along with calculating,
Calculate the total pore volume using Equation 11.

The first database of pressure versus time mentioned above is kept constant −j
In order to perform the adsorption or desorption operation, the computer samples and stores the digital pressure signal on a quasi-continuous basis during the adsorption or desorption operation.

The sampling frequency in this case is controlled by the operator. The specific frequencies selected will be discussed later.

To establish the second database of mass flow rates described above, the commanded voltage source/selector 520 is calibrated at approximately 12 different voltage settings using the blank test results and for each blank test. Determine the actual mass flow rate. The 12 flow rates used as representative ones are S
, T, P, (at standard temperature and pressure) varies from about 0,2 to about α7 ml 7 min. The computer is then programmed with these calibrated flow rates as well as the digital voltages associated with each command voltage.

Thus, when an operator selects one of the calibrated command voltage settings for an operation, command voltage selector 520 automatically sends a corresponding digital signal representing the selected flow rate via line 13'2. Send to Combier 117. Computer 117 uses this information to determine the mass flow rate to be used to calculate the amount of gas adsorbed or desorbed, as described below. The ability of a computer to automatically perform such operations is one advantage enabled by using a substantially constant mass flow rate.

The computer also performs several additional functions that serve to fully automate the system.

That is, the computer operates many functional elements of the device. These operations include opening and closing solenoid valves for the selection of gas from the gas supply, introducing or removing gas from the sample holder 109, evacuation of the sample holder during outgassing, and condensed gas as a preliminary operation to the desorption process. Includes saturation of the sample at . The computer also controls outgassing conditions such as temperature and duration.

The exhaust section reduces the pressure to degas the sample, evacuates the sample holder, and desorbs the agent to be desorbed from the desorption section. The exhaust section includes a vacuum pump 105 and a pressure gauge 120 (
The machine is equipped with a mechanical path vacuum pump collectively designated as an Edward CF25 Gaugehead. Mechanical pump (Varian 0401-/1
820-301) reduces the pressure in the pipe line 204 to j O-
'W immediately decreases, while the diffusion pump (Varian 0160-B2
9D6-501) has a pressure of 10-7 to 1O-8-H.
J is reduced to the desired level.

Pressure gauge 120 reads pressure directly from line 204 to check if the vacuum pump is functioning properly. The low pressure side end of the vacuum pump 1o5 is connected to the pipe line 2.
It is connected to the device via a conduit 204 connected to 05 and 203. By appropriately opening and closing exhaust solenoid valves 1 and 2, the gas discharge and adsorption/desorption sections are alternately coupled to the vacuum pump 105.

The gas discharge section includes an aluminum heating block 14,
one or more conventional cartridge heaters 11
5, an exhaust solenoid needle valve 11, and an AC power source 16 for supplying current to the cartridge type heater. The aluminum block is the sample holder 109'
It is ground to have a space 114 adapted to accommodate the. Although one space 114 and one sample holder 109'l are not shown, the aluminum block 14 is typically adapted to receive and heat four sample holders. Ground glass joint 127', capillary path 1261, stopcock 19'
1 capillary channel 125' and ground glass join M2
4', the sample holder 1091 has a ground glass joint 21. Via an electrically actuated exhaust valve solenoid 11 and line 206 it can be connected to an exhaust or vacuum. To attach the sample to the sample holder 109',
Assembly IJA is disconnected, sample 1101 is placed in sample holder 1091K, and assembly A is reconnected as shown.

To degas the sample, start the vacuum pump 105, open the stop cock 19', close the solenoid valve 1, open the exhaust solenoid valve 2, and first open the exhaust solenoid valve 11 intermittently to degas the sample. 110' is not separated from the sample holder by suction. A cartridge type heater is then turned on and the sample is heated under low pressure until outgassing takes place. Next, stop cock 19'
is closed, while the sample holder is maintained under reduced pressure or vacuum, and the sample 110' is transferred to the adsorption/desorption section while being maintained in an evacuated state. The solenoid needle valve 11 is then closed and the assembly A connected to the sample holder 109' is separated from the ground glass joint 21. The sample holder/assembly IJA combination is cooled and then connected to the adsorption/desorption section as previously described.

All gas conduits shown in FIG. 2 are constructed from 0.05 to α2 inch internal diameter stainless steel tubing up to the metal glass connectors 135 and 136. All glass gas conduits are capillary channels with an internal diameter of 2 to 6 mm and an external diameter of 7 to 12 fi. In addition, all solenoid valves except valve 1 and valve 11 are
Conventional electrically actuated exhaust valve (Hardman -
VA-250-AEl-2-10-21), valve 1 is an air operated M valve (ASCO) and valve 11 is an electrically operated needle valve (Whitey TM).

Valves 4 and 2 are reverse valves that operate in only one direction. When pressure is applied to the low pressure side of these valves 4 and 2, these valves act as check valves. All metal joints are
Welded wherever possible.

In the case of adsorption mode, the line volume represented by VL in equations 1.2 and 3, which must be known, is the line volume 202.20
8.209.126.Point 13 on conduit 122 including 125 and 122 and conduit 210 and coil 212
0 and valve 302.

In the desorption mode, valve 4 is closed and valve 5 is closed.
Starting from 02, the circuit with the line volume represented by the known VL of equations 1.2 and 3 consists of coil 213, line 20
1.207.208.209.126.125 and 1
is defined by the volume up to and including point 130 on conduit 122 and the volume of conduit 210 and coi/l/212.

Typical volumes are as follows. The volume from the valve 18 to the sample holder 109,
9 is about 20-1, the volume from valve 19 to mass flow controller 501 is about 19d, and the volume from the outlet of box 119 in line 209 to point 130 on line 122 is about α6 to 1.8. ml, the volume of conduits 201 and 207 including coil 215 is approximately 41 Ll, and the volume of conduit 210 and coil 212 is approximately 7.5xtl. Therefore, as is clear from FIG.
By arranging 1.202.208.210 and 207 in box 119, only a very small portion of the line volume, which is very important for pressure measurement, is subjected to the fluctuations associated with room temperature and temperature. Therefore, the effects of such fluctuations are reduced to a negligible extent. therefore,
box 119, except for the chamber pipe volume below bath level 129.
It is preferred to maintain about 94 to about 99X, preferably about 96 to about 98%, of the chamber channel volume.

At the start of the adsorption process, once the degassing is complete, valve 2 is closed and the evacuated sample holder 109 and assembly A are connected to glass joint 128 and stopcock 19 is closed.

The sample holder 109 is therefore properly positioned within the liquid bath. Valves 1.4.5 and 6 are then opened and the evacuation pump 105 is activated to evacuate the system. After about 5 minutes, exhaustion is completed, stop cock 19 is opened, and valves 5 and 6 are closed. Valve 3 and one of valves 7-10 are then opened to stabilize the mass flow controller. This stabilization takes approximately 5 minutes. Next, select an appropriate command voltage, close valve 1, and simultaneously open valve 6. The adsorbent enters the sample holder from line 211 via the input path defined by the open and closed valves described above at this point, and the pressure begins to rise. Therefore, pressure versus time measurements are performed to determine the surface area of the sample.

When executing the desorption mode, the degassed sample, including the sample holder 09, is adsorbed as described above.
Place it at the same position as the starting point of 2 modes. Valve 2 remains in the neutral state during the entire operating process. Valves 1.4.5 and 6 are then opened to evacuate the system. At this time, the stopcock 19 is opened (thereby, the sample closes valves 1 and 6,
It is saturated with the relevant adsorbent by opening valve 3 and one of the valves 7 to 10 to select the relevant adsorbent. During this saturation process, valves 4 and 5 remain open. The mass flow rate may initially be at a high level. This is because when the desorption mode is performed, no pressure readings are taken during saturation. Generally, saturation of: requires a long time, such as from about 1 hour to about 8 hours, from which all the pores of the sample must be filled with liquid phase desorbent. However, as a matter of convenience, care should be taken not to oversaturate the sample to the extent that the desorbed agent condenses on the walls of the sample holder 109. If such an event occurs, the desorption period will become unnecessarily long. Once the sample is saturated, desorption mode can be activated. In this desorption mode, valve 5 is kept open and valve 3 is
and 4 and opening valves 1 and 6. The opening and closing of such valves is necessitated by the fact that mass flow controllers operate in only one direction. As a result, the exhaust must draw the desorbed material through the mass flow controller in the forward operating direction. If the sample is properly saturated, the desorbent pressure will remain constant for several minutes. When calculating the calibration amount, the time point 1=0, when the pressure starts to drop, is taken into consideration. At this point, all condensed desorbent on the sample holder walls and between the sample particles is removed.

However, pressure sensing and recording begins upon attachment and detachment.

To perform the combined adsorption and desorption mode, the adsorption mode is first used to saturate the sample and pressure versus time readings are taken during adsorption and desorption.

The examples described below are given as specific illustrations of the invention. Therefore, it is to be understood that the invention is not limited to the details of the embodiments described below. It should be noted that parts and percentages in the following examples and other descriptions herein are to be understood as parts by weight or percentages by weight, unless otherwise stated.

In all of the following examples, apparatus according to the preferred embodiment described in connection with the description of FIGS. 2, 3, and 4 was used.

Example 1 In this example, a calibration blank test cycle in adsorption mode was repeated three times in a row to obtain a pressure versus time graph as shown in FIG. Table 1 below lists the related parameters used.

Table 1 Adsorbent: N2 Saturation pressure Near 600. mHg chamber pipe volume (VL): 2α01 QC sample holder volume, tJCVs, H,): 2 t? S Occ liquid nitrogen bath temperature (Ts, H,): 77.2° Pipe temperature (TL): 29406 Partial pressure range
Number of pressure/time data points sampled from 20 to 1263: 1,2+50 This operating cycle was performed in adsorption mode as described above. From equation 1, the flow rate is S, T
, P, was calculated as α5go/min. fwlettPackard 7225A (coupled to computer)
The pressure versus time relationship was plotted using a plotter. As is clear from FIG. 5, a straight line is obtained, which represents a substantially constant mass flow rate. The degree of dispersion of data points is determined by (1) finding the absolute value of the deviation of the pressure value at each data point from the pressure value corresponding to the best straight line across all data points, and (
2) average the absolute deviation values, and (3) relate this average value to the system pressure and express this value as a percentage.
Calculated from.

Spreadiness is one way to express flow constancy. In this example, the dispersion in all three plots is [
It was 18X.

Example 2 In this example, a calibration blank test cycle was performed in desorption mode. Table 2 below shows the related parameters used.

Table 2 Agent to be desorbed 2N2 Saturation pressure: 760 mHji Chamber pipe volume (ML): 56.68 C
C sample holder volume (■S, H0): 2t50
cc liquid nitrogen bath temperature (T3.H,): 77.
Partial pressure range (P/P) to 2': to
Number of pressure/time data points sampled from O line temperature (TL) = 2960: to 3,000 mass flow rate was calculated to be 0.50 ze/min at 0.24% dispersion. A plot or graph representing the pressure versus time relationship generated by the computer and plotter is shown in FIG. As is clear from FIG. 6, this graph is divided into six line segments ASB and C. Line segment A is
Represents the constant pressure created by the condensed desorbent in the sample holder. At the end of line segment A, all of the condensed desorbent is removed and the graph therefore transitions sharply to a slope section that remains substantially constant throughout line segment B. Line segment B thus represents extraction of the desorbent at a substantially constant flow rate.

At the end of line segment B, at a pressure close to absolute vacuum, the slope changes again. It is at this point that the mass flow controller is no longer able to maintain the flow rate substantially constant. However, this point does not occur until a partial pressure (P/P,) of approximately (1,02 This is considerably lower than the partial pressure required for

Example 3 In this example, an actual adsorption difference was performed. The sample chosen for surface area determination or measurement was silica-7A/Mina ASTM 5 standard Nn N10074 with a surface area reported to be between 281 and 297rn2/g depending on the measurement method used.
It is. The mass flow rate was determined using the results of a previously performed calibration blank test (Examples 1 and 2). The sample is
Outgassing was carried out in the sample holder under vacuum for 700 minutes at 400°C. The adsorption related parameters for this example are summarized in the following table.

Table 5 Adsorbent: N2 Type of sample Nijilikar alumina sample weight: t074 (, F) Sample density: s, 2 (, F/ω) Saturation pressure
Near 6α00 (cod H,!i') Chamber pipe capacity (VI,): 20.01 cc Partial pressure range: 0 to 0.265 Total number of pressure/time data points sampled: 25,440 by computer Of the total sampled pressure/time data points,
For convenience, data are summarized in Table 4 regarding 10 sampled chamber pressure points that are approximately equally spaced on the graph. The actual plot or curve is shown in FIG. Reference pressures corresponding to the reported sampling chamber pressures are also shown in Table 4.

Adsorbed adsorbent S, T, P per duram of sample
.

The volume at tC and the relative adsorbent pressure (P/P, ) at which this amount was adsorbed were calculated from the difference between CRP and SCP using Equation 2 and the total pressure/time database.

The linearized version of the BET equation is the relative pressure (XPr axis) and v(, -Pr
) is plotted from the calculated values for The slope and y-intercept of the plot (curve) were calculated to be 0.000 and α015, respectively. Then the surface area is 28
It was determined to be 4.2 m”/1/.

Example 4 This example illustrates the desorption mode and employs three different experiments. In the first experiment, a perforated glass sample, Sample A, was placed in desorption mode. Real L2
In , a different sample of perforated glass, namely sample B
It was used. In experiment 3, glass samples A and B
50% by weight of this mixture was employed. Each sample has 375
Degassed under vacuum for 700 minutes at °C. Each sample was then saturated with N, the desorbent, until the sample saturation pressure reported in Table 5 was achieved in the sample holder.

Desorption was then started at the mass flow rates reported in Table 5.

The computer sampled the decrease in pressure as a function of time at a frequency of about 60 data points per minute and plotted pressure versus time as shown in FIG. In FIG. 8, Bron (Track N) 1 corresponds to sample AGC, plot 2 corresponds to sample B, and curve 3 corresponds to a mixture of samples A and B.

This example shows that the degree can be obtained. Specifically, the part person of plot 3 corresponds to part a of plot 1, and the part B of plot 3 corresponds to part I of plot 2. However, this degree of resolution can be more clearly seen from the pore size distribution plot of ΔV d @b /ΔRD provided in FIG. 9 from the data in Plot 3. As can be seen from FIG. 9, the pore radius of sample 5 in plot 3 of FIG. 8 is mainly 81 angstroms, and the pore radius of sample B in plot 3 of FIG. 8 is mainly 55 angstroms. This corresponds to the pore size distribution obtained from plots 1 and 2. A summary of suitable test conditions is summarized in Table 5.

Approximately 1401EIJHf! It can be seen that a discontinuity point appears in the graphs shown in FIGS. 5 and 7 at a pressure of . These discontinuities are a result of the automatic region setting of the A/D converter used to generate the graphs in Figures 4-8, and are not caused by the raw data used as the basis for the calculations. It's not something that can be suppressed.

The principles, preferred embodiments, and modes of operation of the present invention have been described above. However, this invention is not to be construed as limited to the particular forms disclosed. What has been disclosed herein is set forth as illustrative only, rather than limiting, and should therefore be construed as illustrative only. Variations and modifications may occur to those skilled in the art without departing from the spirit of the invention.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the preferred components of the device of the present invention, Figure 2 is a simplified diagram showing the components of each part shown in Figure 1, and Figure 3 is a block diagram showing the components of each part shown in Figure 1. The provided mass Uil′, t+ 17
FIG. 4 is a more detailed diagram showing the fourteen components of the control section, and FIG. 4 is a more detailed diagram of the flow control means shown in block 405 of FIG. Figure 5 shows Example 1.
Figure 6 is a graph showing the pressure versus time graph obtained in the adsorption control calibration operation generated in Example 2;
FIG. 7 is a diagram showing a pressure vs. time graph in adsorption mode obtained in Example 5, FIG. 8 is a diagram showing a combination of five pressure vs. time graphs in desorption mode obtained in Example 4, and FIG. The figure shows a graph representing the pore size distribution generated according to Example 4. 1.2.6.4.5.6, 7.8.9.10: Exhaust solenoid valve (ASCOTM) 14: Heating block 16: Power supply 19: Stop cock 20.113: Liquid level controller 101.10
2.106.104: Gas cylinder 108:) Transducer 109 Two sample holders 1101: Sample 0. :Liquid bath container 112:Liquid bath 115:Heater 117:Computer 118Nistop paper recorder 119Two boxes 121:A/D converter 122:Capillary neck 123.124:Ground glass joint 125'112
6': Hair M8 conduit 127': Ground glass joint 128 Ni glass joint 129: Bath level 135.136: Golden glass connector 125.126, 200, 201.202.203.2
04.205.206.208.209.21o121
1: Pipeline 212.215: Coil section 301: Mass flow controller 302: Thermal response valve 311: Pressure controller 401: Circuit board 402.412: Housing 405: Flow controller block 404: Thermistor 405: Proportional integral differential (PID) Controller 40"
6: Heating strip 407: Fan 408: Detection bridge circuit 409: I-form circuit 410: Multiplier 411: Detection coil 501.502 Nibridge resistor 505: Switch 506: Transformer 510: Voltmeter 517: Bridge circuit 520: Selector 600: Comparison controller circuit N side cleaning a (no change in capacity 14) Funeral 1 diagram 111 Figure 3: ? , 2 Figure Proceedings Letter of Interpretation (Method) March 250, 1985 Manabu Shiga, Commissioner of the Patent Office (indication of ii゛ 1988 Patent Application No. 221389)
Person who corrects the number. Related to the incident 1 series Patent applicant masterpiece Omicron Technology Corporation representative week! Same address, same name (8577) Hiroshi Kazama, patent attorney
1. Detailed explanation of the invention in the inventor's jacket specification in the application for amendment ← 1 drawing Contents of amendment 1'f of text as attached (no change in content) Description The detailed description of the invention will be amended as follows. t On page 28, line 11 of the specification, rsurfaeeT
2. On page 29, lines 8-9 of the same page, ``Journal technology'' has been corrected to ``Surface Technology
of Physics E: 5 scientific
InstrumentsJ [Journal of Physics E: Scientific Instruments (Journal of Physics E)
: 5 scientific instruments
) Correct it as J. 5. 1-Analyti in line 40'i% 14 of the same
cal Chern, j.
I will correct it. 4. On page 41, line 13, “Analyt, 1c
al Cham, J has been corrected to ``Analytical Chem, Moon.'' 3. 1'-I on page 41, line 20 to page 42, line 1.
ndian Journal of Te, channel
ogyJ is ``Indian Journal of Technology''.
Technology) J.

Claims (1)

[Claims] 1. A method for determining the amount of gaseous adsorbent adsorbed by a solid adsorbent, comprising: a) providing an evacuated chamber of known volume and releasing gas into the chamber of the adsorbent; b) containing the sample at a known substantially constant mass flow rate for a sufficient period of time to effect adsorption of at least a portion of the adsorbed material by the adsorbent; A gaseous adsorbent is introduced into a chamber in which the mass flow rate is no greater than the equilibrium adsorption amount of the adsorbent by the adsorbent and less than about 0.7 ml/min at standard temperature and pressure conditions. c) establish an equilibrium pressure of the adsorbent as it is introduced into the chamber as a function of time, the equilibrium pressure being the sampling chamber pressure; and d) the sampling chamber pressure of the adsorbent. , correlating the mass flow rate of adsorbent and the time required to achieve the sampling chamber pressure with the amount of adsorbent adsorbed by the adsorbent at the sample chamber pressure. 2. The method of claim 1, wherein the volume and temperature of the chamber are maintained substantially constant during the introduction of the adsorbent. 3. Adsorbent partial pressure (P/P_
2. The method of claim 1, wherein said adsorbent is continuously introduced into said chamber for the time necessary to achieve s). 4. The method of claim 3, wherein the adsorbent is introduced into the chamber for a sufficient time to achieve an adsorbent partial pressure of greater than about 0.35. 5. The method of claim 3, wherein the adsorbent is introduced into the chamber for a period of time sufficient to achieve an adsorbent partial pressure of about 1.0 in the chamber. 6. The method of any one of claims 1 to 5, wherein the mass flow rate of the adsorbent is about 0.05 to about 0.7 ml/min at standard temperature and pressure conditions. 7. The mass flow rate of the adsorbent is from about 0.2 to about 0.5 ml/min at standard temperature and pressure conditions, and during the introduction of the adsorbent into the chamber, possible fluctuations in the mass flow rate are 6. A method according to any one of claims 1 to 5, wherein the mass flow rate is less than about ±0.15%. 8. The mass flow rate of the adsorbent is about 0.2 to about 0.4 ml/min at standard temperature and pressure conditions, and possible fluctuations in the mass flow rate during introduction of the adsorbent into the chamber are , less than about ±0.15% of the mass flow rate. 9. The method according to claim 1, wherein the adsorbent is nitrogen. 10. The method according to claim 1, wherein the adsorbent is a chemisorbent substance. 11. (a) providing an evacuated chamber of known volume and temperature in the absence of an adsorbent sample and adsorbing at a substantially constant mass flow rate as claimed in claim 1 in the presence of said sample; (b) at known volume and temperature conditions; 2. The method according to claim 1, wherein the mass flow rate of the adsorbent is determined by referring to a blank test result in which the mass flow rate can be correlated from the change in the reference pressure per unit time. 12. The sampled chamber pressure as a function of time is set in a manner sufficient to record from about 100 to about 10,000 sampled chamber pressure data points during the course of adsorbent introduction. A method according to claim 1. 13. The method according to claim 1, wherein the amount of the adsorbent adsorbed by the adsorbent is expressed as a volume, and the surface area of the adsorbent is determined by correlating the volume with the sampled chamber pressure. 14. The surface area of the solid adsorbent is about 0.01 to about 150
2. A method according to claim 1, which may be 0 m^2/g. 15. A method for determining the amount of desorbent desorbed as a gas from a solid desorbent saturated with condensed desorbent, comprising: a) a sample of the desorbent having previously degassed and condensed desorbent; (b) providing a chamber of known volume and temperature containing the desorbent in equilibrium with a chamber atmosphere consisting of the desorbent in the gas phase; b) for a period at least sufficient to desorb the desorbent condensed from the pores of the sample; removing said desorbed agent from said chamber at a known substantially constant mass flow rate not greater than the equilibrium desorption amount of desorbed agent from said desorption medium; setting an equilibrium pressure of the desorbed agent as a function, the equilibrium pressure being a sampling chamber pressure of the desorbed agent, and d) a sampling chamber pressure of the desorbed agent, a mass flow rate of the desorbed agent, and the sampling chamber pressure of the desorbed agent; A method comprising correlating the time required to achieve chamber pressure with the amount of desorbent desorbed at said sampling chamber pressure. 16. The method of claim 15, wherein the volume and temperature of the chamber are maintained substantially constant during removal of the desorbent. 17. The method of claim 15, wherein the desorbent is continuously removed from the chamber for a period sufficient to achieve a partial pressure of the desorbent in the chamber of less than about 0.2. 18. The method of claim 17, wherein the desorbent is removed from the chamber for a period sufficient to achieve a partial pressure of desorbent in the chamber of less than about 0.1. 19. The method of claim 17, wherein the desorbent is removed from the chamber for a period sufficient to achieve a partial pressure of the desorbent in the chamber of less than about 0.04. 20. The method of any of claims 15 to 19, wherein the mass flow rate of the desorbent is about 0.2 to 0.7 ml/min at standard temperature and pressure conditions. 21. The mass flow rate of the desorbent is from about 0.2 to about 0.4 ml/min at standard temperature and pressure conditions, and the possible variation in the mass flow rate is not less than 0.03 at the partial pressure of the desorbent. ±0 of the mass flow rate of the desorbent while being removed from the chamber at
．． 20. A method according to any of claims 15 to 19, wherein the amount is not greater than 15%. 22, the desorbent mass flow rate is about 0.2 to 0.3 ml/min at standard temperature and pressure conditions, and the possible fluctuations in mass flow rate are such that the desorbent mass flow rate is approximately 0.2 to 0.3 ml/min at standard temperature and pressure conditions, and the possible fluctuations in mass flow rate are ±0.1 of the mass flow rate of the desorbent during removal.
Claims 15 to 1 not greater than 5%
The method described in any of Item 9. 23. The method according to claim 15, wherein the agent to be desorbed is nitrogen. 24, the desorbent mass flow rate is determined by (a) providing an evacuated chamber of known volume and temperature in the absence of a desorbent sample, the chamber having a condensed desorbent; removed as a gas from said chamber at a substantially constant mass flow rate according to claim 15 in the presence of a sample, establishing an equilibrium pressure of desorbed material in said chamber as a function of time; The equilibrium pressure of the agent is a reference pressure, and (b) the mass flow rate of the desorbed agent is determined by reference to the results of a blank test correlated from changes in the reference pressure per unit time under known volume and temperature conditions. range 15th
The method described in section. 25. The sampled chamber pressure of the desorbed agent as a function of time is measured from about 500 to about 40,000 during the removal process of the desorbed agent.
16. The method of claim 15, wherein the method is set in a manner sufficient to record 00 desorbent sampling chamber pressure data points. 26. The method according to claim 15, wherein the amount of the desorbent to be desorbed by the desorbent is expressed as a volume, and the volume is correlated with the sampled chamber pressure to determine the surface area of the desorbent. 27. The surface area of the desorption medium is about 0.01 to 1500 m^
2/g. 28. In an apparatus for determining the amount of gas adsorbed by a solid adsorbent sample or the amount of gas desorbed from a solid desorbent sample, (1) the solid sample and the gas introduced into the chamber means or the chamber; chamber means defining at least one chamber of a known constant volume for containing gas removed from the means; (2) continuously introducing gas into or continuously removing gas from said chamber means; (3) means for setting the pressure of said gas as a function of time in said chamber means as said gas is introduced into said chamber means or removed from said chamber means; ) controlling the mass flow rate of the gas being introduced into or being removed from the chamber;
(a) the mass flow rate is at least about 0.0% of the gas in the chamber;
02 to about 1.0, and (b) does not exceed the equilibrium adsorption of the gas by the adsorbent sample during the introduction of the gas and the removal of the gas. (5) means for evacuating the gas from the chamber means via the control means during the removal of the gas from the chamber means; (6) means for maintaining a known temperature of the gas within the room substantially constant. 29, a patent in which the control means is a mass flow controller having an electronically actuated variable opening for controlling the mass flow rate of gas being introduced into or being removed from the chamber means; 29. Apparatus according to claim 28. 30. The control means controls the mass flow rate of the gas being introduced into or being removed from the chamber means from about 0.05 to about 0.7 m at standard temperature and pressure conditions.
29. The device according to claim 28, wherein the device can be controlled to have a speed of 1/min. 31. The control means is capable of controlling the mass flow rate of the gas from about 0.02 to about 0.05 ml/min at standard temperature and pressure conditions, and the variation in the mass flow rate during the introduction or withdrawal of the gas is 29. The apparatus of claim 28, wherein the mass flow rate is not greater than ±0.15%. 32. The control means is capable of controlling the mass flow rate of the gas to be about 0.2 to about 0.4 ml/min at standard temperature and pressure conditions, and the variation in the mass flow rate is within about ± of the mass flow rate. 29. The device of claim 28, wherein the amount is not greater than 0.15%. 33. An apparatus for determining the amount of gas adsorbed by an adsorbent sample solid or desorbed from a desorbent solid sample, comprising: (1) means for defining at least one chamber of known volume; , the chamber defining means (i) introduces gas into or removes gas from the chamber, (ii) introduces a solid sample into or removes the solid sample from the chamber, and (iii) (2) an input passageway in fluid communication with said chamber-defining means for introducing gas into said chamber and for removing gas from said chamber; a first conduit means defining an output path of the chamber, wherein a portion of the volume of the input path leading to the first conduit means constitutes a portion of the chamber of known volume during the introduction of gas into the chamber; death,
and (3) a portion of the volume of said output path of said first conduit means constitutes a portion of said chamber of known volume during removal of gas from said chamber; (4) control means having an input and an output, the control means controlling the mass flow rate of the gas so that (a) the gas is continuously in the chamber; and (b) the partial pressure of the gas in the chamber varies from about 0 to about 1 during the introduction of the gas. , and when the mass flow rate changes from about 1 to about 0.02 during gas withdrawal, the mass flow rate is no greater than the equilibrium adsorption amount of gas by the adsorbent sample during the gas introduction and from the desorbent sample during the gas withdrawal. the input of said control means is in series fluid communication with the input and output passages of said first conduit means, and the output of said control means is (a) in serial fluid communication with an input path of said first conduit means; and (b) in serial fluid communication with an output path of said first conduit means upstream of said exhaust means; in said chamber, a first conduit;
The combination of control means and evacuation means is referred to as assembly A; (6) pressure recording means coupled to said pressure sensing means for recording the pressure sensed by said pressure sensing means as a function of time; (7) is provided in said assembly A to (1) interrupt fluid communication between an output path of said conduit means, including said exhaust means, and said chamber during the introduction of said gas into said chamber;
ii) valve means for isolating fluid communication between the input passage of the first conduit means and the chamber during removal of the gas from the chamber; (8) for controlling the temperature of the chamber to be substantially constant; and control means. 34, wherein the control means is an electronically actuated mass flow controller with variable opening for controlling the mass flow rate of gas being introduced into or being removed from the chamber means. 34. The apparatus of claim 33. 35. The control means controls the mass flow rate of the gas being introduced into or being removed from the chamber means from about 0.05 to about 0.7 ml at standard temperature and pressure conditions.
34. The device according to claim 33, wherein the device can be controlled so as to achieve a speed of 30 minutes. 36. The control means is capable of controlling the mass flow rate of the gas from about 0.2 to about 0.5 ml/min at standard temperature and pressure conditions, and the variation in the mass flow rate during the introduction or withdrawal of the gas is 34. The apparatus of claim 33, wherein the mass flow rate is not greater than ±0.15%. 37. The control means is capable of controlling the mass flow rate of the gas to be about 0.2 to about 0.4 ml/min at standard temperature and pressure conditions, and the variation in the mass flow rate is within about ± of the mass flow rate. 36. The device of claim 35, wherein the amount is not greater than 0.15%. 38. The apparatus according to claim 33, further comprising gas supply means for intermittently supplying gas to the input path of the conduit means upstream of the control means for introducing gas into the chamber means. . 39. The apparatus of claim 38, further comprising means for outgassing the solid sample under reduced pressure and at elevated temperature using evacuation means. 40. The chamber means has a sample holder portion and a conduit portion, the sample holder portion including a valve removably attached to the conduit portion for confining a vacuum or reduced pressure within the sample holder portion; 40. The apparatus of claim 39, wherein the conduit portion forms part of the output and input passages of the conduit means. 41. The apparatus of claim 40, wherein the removably mounted sample holder portion is engageable with the gas release means. 42, the chamber has a known constant volume, and the temperature control means:
41. The apparatus of claim 40, wherein the temperature of the sample holder part of the chamber can be maintained substantially constant. 43. The apparatus of claim 33, wherein the pressure recording means comprises a computer. 44, the control means comprising: an enclosure having an exterior surface and defining an interior space; means for substantially constant control of the temperature within the interior space; and second conduit means; a conduit means engages in fluid communication with the input and output passages of the first conduit means;
an input passageway for directing a flow of gas into the interior space from an input port provided on an external surface of the enclosure and engaged in fluid communication with the input and output passageways of the first conduit means; defining an output passage in fluid communication with the input passage of the second conduit means for directing the flow of gas from the interior space to an output port on the exterior surface of the enclosure; an elongate sensing conduit means having an internal passageway disposed in the interior passageway and having an inlet and an outlet for directing the flow of gas, the inlet of the sensing conduit means being engaged in fluid communication with the input passage of the second conduit means; The outlet of the sensing conduit means engages in fluid communication with the output passage of the conduit means, and the internal passageway of the sensing conduit has a diameter not greater than 0.2 mm and is in contact with the sensing conduit within the internal space of the enclosure. a first sensor arranged to sense a temperature difference induced by a change in the mass flow rate of gas flowing from the inlet to the outlet of the sensing conduit, the first flow meter means for generating an output signal of a gas; and means for generating a reference second output signal proportional to a selected mass flow rate of gas; means for comparing the two output signals and generating a third output signal representative of the difference between the first and second output signals; the sensing conduit and the output path of the second conduit means to controllably separate fluid communication between the sensing conduit and the output path of the second conduit means; valve means actuated by the third output signal for enabling adjustment of the mass flow rate of gas flowing from the sensing conduit to the output path of the second conduit means; means for equilibrating the temperature of the gas passing through the input path of the conduit means with the substantially constant temperature of the interior space of the enclosure before the gas enters the sensing conduit means; 34. The apparatus of claim 33, further comprising means for controlling the pressure at the inlet of the means to be substantially constant. 45. The device of claim 44, wherein the pressure sensing means are arranged within the interior space of the enclosure. 46, the chamber has a sample holder portion and a conduit portion, the sample holder portion being removably attached to the conduit portion and provided with a valve for confining a vacuum state within the holder portion; portions forming part of the output and input passages of the first conduit means such that about 96 to about 98% of the volume of the conduit portion maintains a substantially constant temperature of the gas within the wall interior space. 45. The apparatus of claim 44, wherein the apparatus is disposed within the wall interior space to control. 47, the diameter of the internal passage of the sensing conduit in the control means is 0;
．． 45. The device of claim 44, wherein the device is not larger than 0.05 mm. 48. Means provided in the control means for controlling the temperature of the interior space of the enclosure is disposed within the enclosure to bring the atmosphere outside the enclosure into fluid communication with the interior space, thereby controlling the temperature of the interior space. valving means for a space to receive air from and discharge air from an environment external to the enclosure; and a first temperature output signal for sensing and proportional to the temperature of the atmosphere within the enclosure interior space. means for generating a second temperature output signal proportional to the difference between the first output signal and a reference signal representative of a selected temperature; and means for generating a second temperature output signal proportional to the difference between the first output signal and a reference signal representative of a selected temperature. means for heating the atmosphere within the interior space actuated by a signal; and means for continuously drawing air into the interior space from outside the enclosure at a rate of about 10 to 75 times the volume of the interior space per minute. Claim 44 comprising means for circulating.
Apparatus described in section. 49. The input path of the second conduit means forms a coil in order to ensure that the temperature of the gas passing through the input path is in equilibrium with the temperature of the internal space of the enclosure. Device. 50, flow meter means in the control means comprising a plurality of self-heating sensor element coils having adjacent ends disposed along the flow path of the gas flowing through the sensing conduit means external to the sensing conduit means; one of the sensor elements is located closer to one end of the sensing conduit than the other sensor element, and the sensor element coil is formed from a temperature sensitive resistive wire wrapped around an external surface of the sensing conduit means. means for heating the sensor element and detecting a temperature difference in the sensor element induced by the variation in the mass flow rate; and means for generating a first output signal.
Apparatus described in section. 51. The apparatus of claim 44, wherein the valve means of the control means is a thermally responsive valve responsive to thermal expansion of the actuator relative to the reference member. 52, the first conduit means engaged with the pressure sensing means being adapted to form a coil for enabling the temperature of the gas within the conduit means to equilibrate with the temperature of the interior space of the enclosure; 46. The apparatus according to claim 45. 53. Temperature control means for controlling the temperature of the sample holder portion of the chamber to be substantially constant, comprising: a) a liquid bath maintained at a substantially constant temperature; and b) the temperature control means for controlling the temperature of the sample holder portion of the chamber to a substantially constant temperature; container means adapted to receive the sample holder portion of the chamber for immersion therein; and a liquid level control for maintaining a substantially constant level of the liquid bath in which the sample holder portion is immersed. 47. The apparatus of claim 46, comprising means. 54, a liquid level control means for sensing the level of the liquid bath and generating a signal when the level deviates from a preselected level; and actuated by the liquid level sensing means signal. Claims comprising means for introducing fresh liquid into said bath and means for separating vaporized liquid from said fresh liquid before introducing said fresh liquid into said bath. The device according to item 53.