ASTM_D_3663_-_03_2015.pdf

Designation:D366303(Reapproved 2015)Standard Test Method forSurface Area of Catalysts and Catalyst Carriers1This standard is issued under the fixed designation D3663;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 determination of surfaceareas of catalyst and catalyst carriers that have Type II or IVnitrogen adsorption isotherms,and at least 1 m2/g of area.Avolumetric measuring system is used to obtain at least four datapoints which fit on the linear BET2equation line.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3D3766 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 Consult Terminology D3766 for definitions of otherterms used.3.2 Definitions:3.2.1 surface area of a catalystthe total surface of thecatalyst.It is expressed in square metres per gram.3.3 Symbols:PH1=initial helium pressure,torrPH2=helium pressure after equilibration,torrTH1=temperature of manifold at initial helium pressure,CTH2=temperature of manifold after equilibration,CP1=initial N2pressure,torrT1=manifold temperature at initial N2pressure,KT1=manifold temperature at initial N2pressure,CP2=pressure after equilibration,torrP0=liquid nitrogen vapor pressure,torrTs=liquid nitrogen temperature,KX=relative pressure,P2/P0Vd=volume of manifold,cm3Vx=extra volume bulb,cm3Vs=dead-space volume,cm3Ws=mass of sample,gW1=tare mass of sample tube,gW2=sample+tare mass of tube,gVds=volume of nitrogen in the dead-space,cm3V1=see 10.4.4V2=see 10.4.6Vt=see 10.4.7Va=see 10.4.9Vm=see 10.8T1x=initial extra-volume bulb temperature,KT1 x(i)=initial extra-volume bulb temperature,CT2 x=extra-volume bulb temperature after equilibrium,KT2 x(i)=extra-volume bulb temperature after equilibrium,C4.Summary of Test Method4.1 The surface area of a catalyst or catalyst carrier isdetermined by measuring the volume of nitrogen gas adsorbedat various low-pressure levels by the catalyst sample.Pressuredifferentials caused by introducing the catalyst surface area toa fixed volume of nitrogen in the test apparatus are measuredand used to calculate BET surface area.5.Apparatus45.1 Aschematic diagram of the apparatus is shown in Fig.1.It may be constructed of glass or of metal.It has the followingfeatures:1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.01 on Physical-Chemical Properties.Current edition approved April 1,2015.Published June 2015.Originallyapproved in 1978.Last previous edition approved in 2008 as D3663 03(2008).DOI:10.1520/D3663-03R15.2Brunauer,Emmett,Teller,Journal of American Chemical Society,JACS,No.60,1938,p.309.3For 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.4Automated equipment is commercially available.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.1 Distribution Manifold,having a volume between 20and 35 cm3,(Vd),known to the nearest 0.05 cm3.This volumeis defined as the volume between the stopcocks or valves andincludes the pressure gauge.5.1.2 Vacuum System,capable of attaining pressures below104torr(1 torr=133.3 Pa).This will include a vacuum gauge(not shown in Fig.1).Access to the distribution manifold isthrough the valve V.5.1.3 Constant-Volume Gauge or Mercury Manometer,ca-pable of measurements to the nearest 0.1 torr,in the range from0 to 1000 torr(1 torr=133.3 Pa).NOTE1See,for example,the article by Joy5for a description of aconstant-volume manometer.5.1.4 Valve(H),from the helium supply to the distributionmanifold.5.1.5 Valve(N),from the nitrogen supply to the distributionmanifold.5.1.6 The connection between the sample tube and the Svalve can be a standard-taper glass joint,a glass-to-glass seal,or a compression fitting.5.1.7 Extra Volume Bulb,(Vx),should be 100 to 150 cm3,known to the nearest 0.05 cm3.Vxincludes the volume of thestopcock bore in the glass apparatus.5.2 Sample Tubes,with volumes from 5 to 100 cm3depend