ASTM_D_4567_-_03_2013.pdf

Designation:D456703(Reapproved 2013)Standard Test Method forSingle-Point Determination of Specific Surface Area ofCatalysts and Catalyst Carriers Using Nitrogen Adsorptionby Continuous Flow Method1This standard is issued under the fixed designation D4567;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the single-point determinationof the surface area of catalysts and catalyst carriers that exhibitType II or Type IV nitrogen adsorption isotherms using anitrogen-helium flowing gas mixture.This test method isapplicable for the determination of total surface areas from 0.1to 300 m2,where rapid surface area determinations are desired.1.2 Because the single-point method uses an approximationof the BET equation,the multipoint BET method(Test MethodD3663)is preferred to the single-point method.NOTE1This is particularly true when testing microporous materials.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D3663 Test Method for Surface Area of Catalysts andCatalyst CarriersD3766 Terminology Relating to Catalysts and CatalysisE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 DefinitionsSee Terminology D3766.3.2 Symbols:Acs=cross-sectional area of nitrogen,16.2 1020m2.CI=integrator counts.CITa=integrator counts corrected for ambient temperature.CIPa=integrator counts corrected for ambient pressure.N=Avogadros number,6.02 1023,molecules/mole.P=partial pressure of nitrogen,torr.Pa=ambient pressure,torr.Po=saturated equilibrium vapor pressure of liquidnitrogen,torr.R=gas constant,82.1 cm3atm/K mole.Ta=ambient temperature,K.V=volume of nitrogen adsorbed at ambient temperatureand pressure,cm3.W1=tare of sample cell,g.W2=sample mass+tare of sample cell after analysis,g.Ws=mass of sample,g.4.Summary of Test Method4.1 The sample is degassed by heating in a flow of inert gasto remove adsorbed vapors from the surface.The sample isthen immersed in a liquid nitrogen bath causing adsorption ofnitrogen from a flowing mixture of a fixed concentration ofnitrogen in helium.When adsorption is complete,the sample isallowed to warm to room temperature causing desorption,which results in an increase in the nitrogen concentration in theflowing mixture.The quantity of nitrogen gas desorbed isdetermined by sensing the change in thermal conductivity.4.2 Calculation of the surface area is based on a modifiedform of the BET equation.5.Significance and Use5.1 This test method is useful for determining the specificsurface area of catalysts and catalyst carriers for materialspecifications,manufacturing control,and research and devel-opment in the evaluation of catalysts.1This test method is under the jurisdiction of Committee D32 on Catalysts andis the direct responsibility of Subcommittee D32.01 on Physical-Chemical Proper-ties.Current edition approved April 1,2013.Published August 2013.Originallyapproved in 1986.Last previous edition approved in 2008 as D4567 03(2008).DOI:10.1520/D4567-03R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Apparatus6.1 Aschematic diagram of the apparatus is shown in Fig.1.The apparatus may be constructed of glass or metal tubing.Ithas the following features:6.1.1 Differential Flow Controller from the gas inlet valveto a flow control valve to eliminate fluctuations in the gas flow.6.1.2 Two Thermal Conductivity DetectorsA referencedetector(A)to sense the nitrogen-helium gas mixture and asecond detector(B)to sense changes in the gas mixture afterflowing through the sample cell.The two detectors are initiallybalanced to allow the detection of changes in the nitrogenconcentration.6.1.3 Flow-Through Sample Cells,of various volumes andshapes depending on the application.6.1.4 Two Equilibration Tubes selected by a selector valve,between the sample cell and detector(B).The small volumetube has a volume of approximately 20 cm3and the largevolume tube has a 100 cm3capaci