GB/T 19587-2004 Determination of specific surface area of ​​solid substances by gas adsorption BET method

This standard specifies the method for determining the specific surface area of ​​solid substances by the gas adsorption BET principle. This standard is applicable to the determination of the specific surface area of ​​powders and porous materials (including nanopowders and nano-scale porous materials). The measurement range is 0.001 m2/g to 1 000 m2/g. GB/T 19587-2004 Determination of the specific surface area of ​​solid substances by the gas adsorption BET method GB/T19587-2004 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
GB/T19587--2004
Determinatiun af the specific surface area of ​​solidsby gas anlsorplion using Lhe RFT melhckd(1S)0277F695.NEQwww.bzxz.net
2004-09-29 Issued in the market
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Administration of Standardization of the People's Republic of China
2005-04-01 Implementation
CB/T19587-2304
This standard is not equivalent to the IS2?7::9 gas adsorption method for determining the specific surface area of ​​solids relative to the 1S?:1995 Feng'an, Cheng Shao, modified content! The capacity of the culture,
a quality measurement model has been improved:
added the balance adsorption force, saturated gas pressure, pressure knife adsorption capacity, new area, single layer of killing words;
-5.2 auxiliary equipment has been improved, the balance Du distribution has been added, the sample tooth hot gas pressure temperature calculation has been added, and the particle size specific surface area formula has been added in Section 5. The capacity of the sand reduction:
the figure in the international standard: the control device in Figure 4 and the adsorption streamlines in Figure 6 have been eliminated: the international standard and Appendix H are both European standards: the general effect of the internal consultation:
the first chapter puts forward the capacity of the space within the color cow skin 3 kinds of methods of absorption. The calculation formula of the attached quantity, the former international environmental standard said "the gas state method should be used to determine the amount of waste gas". This standard is proposed by the National Nonferrous Metals Association: the standard is drafted by the Director of the National Nonferrous Metals Association: TC/SC:> The standard is drafted by the Director of the National Nonferrous Metals Association.
The drafters of this standard are Wei Yun, Li Zhongquan, and the scope of this standard is 1.
The gas adsorption ET method is used to determine the specific surface area of ​​solid substances CB/I19587-204
This international standard specifies the gas adsorption HFT method to determine the specific surface area of ​​solid substances. This standard is applicable to the determination of the specific surface area of ​​1.66 million materials (packaged materials and meter-level Lefan materials), and the scope is 1. Ul in'/t.-1 OGc ra*/g:
2 Normative references:
The following documents may become the references of this standard through the opening of this standard. All referenced documents with a transfer date, the same as the single (excluding the error) or revised version, shall not be used in this standard. However, the new version of this document can be used for the research work done according to the vehicle standard. All undated documents: the new version shall be used for this standard. GB/T14 Sampling technology and symbols for powder metallurgy
3.1 In this language
, adgorption
When the body is absorbed on the surface of the concentration of the variable substance, the concentration of the substance is zero. 3. 1.2
plysisorption
absorption is the process of adsorption of gases by a combination of forces and the change of pressure or temperature, which may affect the adsorption of gases. 3.1.3
absorption of gases adsorptive
the adsorbed body.
adsorption dsorbeul
the adsorbed gas is a solid substance adsorbed on the surface of the adsorbent.
the equilibrium adsorption pressure is the pressure at which the gas reaches equilibrium.
salnratinn vapour pressure
and the vapour pressure
at the adsorption temperature determine the gain of the adsorbent. 3. 1.8
relative pressure
Relative pressure
The ratio of the equilibrium adsorption pressure to the specific kinetic energy3. 1. 9
adsurpjouamnnt
Adsorption amount
The amount of gas adsorbed by the adsorbent under semi-limiting pressure, 1
CB/T 19587-2004
Adsorption isotherm dyrpliunsutherm
At constant temperature, the curve obtained by plotting the adsorbed gas against the equilibrium three-dimensional relative pressure. 3.1.11
molecular cross-sectional area
molecular cross-sectional area
when there is no complete monolayer: and the molecular surface area near the mountain is measured evenly. 3.1.12
monolayer volume
mcnlerammnt
in the process of finding the monolayer, the surface area of ​​the substance is measured. 3.1.13
specific surface area
spifie surlace are
the surface area of ​​a substance in a state of mass (or per unit volume). 3.7
This specification uses the surface area 1.
Desorption evaluation area
Standard peak area
BET start
BET number
Production and particle size at the end of the sample
The sample is opened
The quality of the sample is under equilibrium. The quality of the sample is at ten points in a single state. The order of the test is flat. Disease prevention force reduction and the quality of the test group can be replaced with teaching 5.222×13
flat Xie inhalation
atmospheric force
change people controlled Chinese gas extension force
Chinese gas products
★The most human body and mind with
technique spirit and qi
original basic gas composition
micro-combined gas total resources positive
4 principles|| tt||Measurement process
Real-time environment zone
Time drop zone milk flow)
Table 1)
Gas limit standard in measuring tube
Tube position volume
Gas adsorption after substitution and residual adsorption in sample bubble (theoretical separation) Gas phase in tube and attached letter (standard) standard note volume General volume
1 Coulomb adsorption weight internal product volume: called 1,22.114 effective density of product material
Gas internal density: called gold
Fuzi Shixin Commercial
Beijing volume calibration instrument
Single point measurement derived single attachment protocol
Single point measurement derived expansion resistance attachment company
GB/T19587—2004
g: cru
release the sample in the gas system, its material surface <particles outside and inside the surface of the former wine and machine, see net 1) under low pressure will occur species adsorption, when the adsorption reaches equilibrium, the adsorption of the gas plate is not small, batch according to KKT method 1) to find out the test column single molecule will be instantly attached, and the ratio of the sample is calculated. Use the actual expression and the method of the particle table blood sorrow Figure 1
Let P/P be X, TI-Pr.sY.S.
is 1. For, we get a straight pick formula A, the ratio of 3
CR/T195A7--20Q4
Y-AXF. The graph is shown in Figure 2
Figure 2E
lead 2 in the sweep juice. Fire C5, usually the national practice equipment, he lowered the point sometimes deviated from the classic point when calculating the sound content.
general series relative pressure P/, and the attached gas 1 measurement, the dosage rate A and the pad single layer penetration volume B are calculated by BET or least squares method, but it cannot be used to quantitatively calculate the adsorption heat. When using hydrogen adsorption gas, the material rate is relatively high, and it is usually water (100%), the surface area and the mass transfer ratio are calculated by the average surface area of ​​all the cells in the middle layer. It is usually considered that the gas is suitable for adsorption. For this case, the flow rate of the instrument is not high or low. For example, the gas is measured on the same liquid. The results show that the molecular weight is small. The measurement temperature is different. There will be deviations. In order to achieve the desired results, the new clothes are measured several times in detail and the standard cross-sectional area is reported at a temperature of K. 6? Then the 15th formula can be used to calculate the ratio of the original area of ​​the mass
Su - 4. 3V.
The total volume of the crown gas of the pass band is: 7? K .1ec nm
37 K crown gas.1. 2.
5 Instruments and materials
5.1 Main instruments
Mark I give, the new method is the instrument is the principle of the small idea: the new principle can get the power of the room I can use this instrument: only out
5. 1. 1 Capacitance method
Customer single method measurement of the positive projection device principle small idea see Figure 31
1 selection;
La and the nature of the implementation of the interaction!
Stand in the air
One "body of these
5. 1. 2 Gravimetric method
Figure 3 Weight method specific surface area determination instrument
GB/T19587—2004
Five weight method cooling plate 4, through the elastic balance or the balance to weigh the amount of the absorbed. And:
Absorbent point scanning plate
General inspection system!
Figure 4 Weight method specific surface area determination instrument
5.1.3 Gas chromatography
Gas sweeping chromatography measurement method is shown in Figure 5. The main gas flow system is composed of a thermal conductivity cell. 1 Open product
Right flow hydrogen business point change:
Huining station stability ticket!
Gas science and technology components,
Library 5 Gas chromatography specific surface area measurement definition
CB /T195B7-.2004
5.2 Auxiliary equipment
5.2.1 Balance
5.2.2 Dewar flask
Required size is more uniform or liquid oxygen storage equipment. 5.2.3 Sample tray
The sampler of the most complete method is to place the sample in a sloped bubble with a core inside to reduce the accumulation of the sample tube and prevent the test column from being evacuated. The typical sampler is shown in Figure a). The gas chromatography method uses a section of the sample container (Figure 6). The container of the gas chromatograph method is a deformation glass tube to hold the sample, and the actual sample container is shown in Figure (Figure 7). The mother method is a sample container (Figure 8). 5.2.4 Vapor pressure meter
h) uses a selector||tt ||Week 0 sample meal
(:) A batch of instruments are used as
natural gas pressure and temperature to measure the pressure and temperature of nitrogen or gas. The diagram of a real pressure thermometer is shown in the figure. The solid part of the tube is filled with people, and the other space can be filled with nitrogen or gas. The whole gas pressure thermometer
5.3 Materials
5.3.1 If the gas is absorbed, it will be seen that the gas, gas or oxygen! Its humidity is not less than 5.99%. It must be kept stable during the measurement. 5.3.2 Gas (such as gold gas, its purity is not less than 5.3.3 Starved hydrogen or body oxygen. There should be completely pure quality, so that the gas adsorption and gas production and power are guaranteed to be stable. E sampling
The joint description shall be in accordance with G3/314. || tt||? Test frequency
7.1 Degassing
Before the test, the sample must be degassed for nanometer-level products. Degassing removes the sample and removes the substance that is absorbed by the sample. The sample is degassed by heating the sample at high temperature. The amount of gas can be determined by the hot air or the degassing method with the same time according to GB/T19587-2004. When the sample is degassed under the vacuum, the temperature in the chamber reaches 1Pu or better. When the pressure, composition and quality of the sample are stable, degassing is completed: degassing, the sample container is ready for measurement, see Figure and Figure! , G
a precipitation is low, need long time to dormant gas
- the first with the industry;
, - in the high point of the group of products to do the gas escape. Figure B melt product heat to the curve
P: - gas complete, will be good
P: - gel gas six complete
r - confirm gas:
Figure 9 degassing force curve
7,2 measurement
7. 2. 1 volume method
production of non-note system benefit method, the amount of adsorbent into the single chamber (Figure 3). Each time, the sample is measured by time 1, so the gas in the finite constant volume decreases, and the self-adsorption reaches equilibrium. The amount of adsorbed gas is the difference between the gas ratio in the most critical moment and the remaining gas in the sample pool after the adsorption equilibrium. This amount is determined by the gas state process, which must be determined before and after the isothermal process is stopped: this small volume is calibrated at the temperature of the measurement. Yes! For some materials that adsorb nitrogen, calibration should be performed on the source of the gas before the determination of the effective gas. In the continuous scalar method, the amount of gas absorbed during the measurement can be calculated by the difference in the flow rate and the time of the standard or normal reading: 7.2.2 Sub-scalar method || tt || scalar method See Figure 1. The scalar method is similar to the original instrument used. After the estimation, the absorbed gas reading is obtained by measuring the sample quality and the accumulation of the two mice. It is not necessary to identify the dead volume, which simplifies the process: In the continuous scalar method, a sensitive balance is used to measure the relationship between the absorbed gas and the original gas. Before measuring, the gas is collected at a temperature of one degree. The buoyancy of the sample is eliminated by using a balance that is gradually replenished with the sample. The measurement is performed by the technician to ensure the accuracy.
In the non-continuous change method, the adsorbed gas is introduced step by step while the pressure remains unchanged. When the amount of the product reaches a constant value, it is positive. 7.2.3 Gas chromatography method
Nitrogen (or hydrogen) gas is the adsorbed gas, and ammonia (or hydrogen) gas is the relative gas. After the two gases are condensed in a certain proportion, they flow through a heat conductivity cell at a pressure close to atmospheric pressure. The flow rate of ammonia or oxygen is adjusted to about mI/i/m3/m3/m3. After the two gases are combined, the total amount of the combined gas is measured by the bubble flowmeter. Then the power supply is adjusted and the monitoring zero point is adjusted. The instrument can be used to measure the sample. When the adsorption reaches the lower equilibrium, a thermal conductivity test is performed. When the sample is removed from the sample cell, a desorption peak opposite to the adsorption peak is detected. The detector must be calibrated with the volume of adsorbed gas injected. The size of the sample peak and the standard peak should be similar. The desorption peak is easy to be compared with the standard peak of the injected gas sample. Why? The upper eluent must be expanded, and the pure adsorbent gas with known absorption is used for calibration. The sample peak and the standard are approximately equal. 8 Calculation 8. Volumetric method 8.1 Dead volume factor The dead volume factor is calculated by the formula (7). 3.1.2 The amount of adsorbed gas charged The amount of adsorbed gas charged is calculated by the formula. Gas chromatography adsorption peak and desorption peak are calculated by the carrier 27.i. 15P, - PV : 5'(273.5 - )P, V = : 0.1125 228(273.170) 9. 1.3 The remaining adsorption volume
is positive and the balance is reached, the remaining adsorbent is missing (9) to obtain. v. = F++
8..4 The amount of gas during pregnancy
8.1.5 Specific surface area
-.313 25 x -3*(273. :5
The sample is taken and forgotten, and the empty mind method is obtained, 8.2 The reset method
The sample conducts the adsorption of the gas year to obtain the ratio of ... Relative pressure
is obtained by equation (12)
8.3.2 Adsorbed gas
The amount of adsorbed gas outside the adsorbed gas is obtained by equation (1) and equation (11). =W
.013 25 x0*1273.1: -
8.3.3 Specific surface area
The specific surface area of ​​the sample can be obtained by the method described above. 8.4 Single point method measurement
CB/I19567—2004
（12）
In general, the value in the BE equation is relatively large, and the nitrogen gas is used as the failure function. C is often between 100300. When (the signal ratio is large, the post distance BV rate is A1/V, then the equation 1) is converted into the formula). Formula (1=) is the converted F formula. When the experiment is carried out, the (blue dotted line point in Figure 1) can be measured. -. -- V1- HP.?
（153
The specific surface area of ​​the product is relatively large compared with the method described above. Usually the results obtained by the single point method are relatively large, and the setting of the bar is not more than three times: using the single point method, for /. Sound in u. "~.By comparing the single-point T diagram and the multi-point BET diagram, the single-point measurement V and V are measured on similar materials. The difference between the single-point measurement and the multi-point measurement is calibrated by the following values ​​and the force method: a) Cast a suitable distance value, and then use it for subsequent single-point analysis: b) Calculate the node parameter center value, and then correct the single-point analysis by the formula (16): Vna
month. 5 Average particle size
1(P/PC=)
Particle size Average particle detection formula (1): Formula (1?) is only suitable for materials that are relatively spherical.
9 Result expression
obtained ratio private connection is three effective teaching digits, S
CB/I19587—2004
test report
test report implementation includes the following contents:
b) monitoring test compensation temporary fee explanation:
) only use the instrument
mountain and the gas type and its distribution cross-sectional code: degassing record,
) how or liquid) saturated steam force
linear situation of drawing, if not using annual point disk, should be accompanied by the value of the operation;
this mark does not make provisions for the operation:
》may affect the conclusion of the light how to estimate
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