ASTM D4780-2012(2017)e1 Standard Test Method for Determination of Low Surface Area of Catalysts and Catalyst Carriers by Multipoint Krypton Adsorption《用多点氪吸附法测定催化剂的低表面面积的试验方法》.pdf
《ASTM D4780-2012(2017)e1 Standard Test Method for Determination of Low Surface Area of Catalysts and Catalyst Carriers by Multipoint Krypton Adsorption《用多点氪吸附法测定催化剂的低表面面积的试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D4780-2012(2017)e1 Standard Test Method for Determination of Low Surface Area of Catalysts and Catalyst Carriers by Multipoint Krypton Adsorption《用多点氪吸附法测定催化剂的低表面面积的试验方法》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D4780 12 (Reapproved 2017)1Standard Test Method forDetermination of Low Surface Area of Catalysts andCatalyst Carriers by Multipoint Krypton Adsorption1This standard is issued under the fixed designation D4780; the number immediately following the designation indicates the year oforigin
2、al 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.1NOTESubsesction 8.1 was corrected editorially in February 2017.1. Scope1.1 T
3、his test method covers the determination of the specificsurface area of catalysts and catalyst carriers in the range from0.05 to 10 m2/g. A volumetric measuring system is used toobtain at least three data points which fall within the linear BETregion.1.2 The values stated in SI units are to be regar
4、ded asstandard. No other units of measurement are included in thisstandard.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 determin
5、e the applica-bility 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 MethodsE45
6、6 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsConsult Terminology D3766.3.2 Symbols:PH1= initial helium pressure, torr.PH2= helium pressure after equilibration, torr.TH1= te
7、mperature of manifold at initial heliumpressure, C.TH2= temperature of manifold after equilibration, C.P1= initial Kr pressure, torr.T1= manifold temperature at initial Kr pressure, K.T1= manifold temperature at initial Kr pressure, C.P2= Kr pressure after equilibration, torr.T2= manifold temperatur
8、e at P2,K.T2= manifold temperature at P2, C.Po,N= liquid nitrogen vapor pressure, torr.Po,krypton= calculated krypton vapor pressure, torr.Ts= liquid nitrogen temperature, K.X = relative pressure, P2/Po,krypton.Vd= volume of manifold, cm3.Vs= the apparent dead-space volume, cm3.Ws= weight of sample,
9、 g.W1= tare weight of sample tube, g.W2= weight of sample plus tare weight of tube, g.Vds= volume of krypton in the dead space, cm.3V1= See 11.3.5.V2= See 11.3.6.Vt= See 11.3.7.Va= See 11.3.9.Vm= See 11.6.4. Summary of Test Method4.1 A catalyst or catalyst carrier sample is degassed byheating in vac
10、uum to remove absorbed vapors from thesurface. The quantity of krypton adsorbed at various lowpressure levels is determined by measuring pressure differen-tials after introduction of a fixed volume of krypton to thesample at liquid nitrogen temperature.The specific surface areais then calculated fro
11、m the sample weight and adsorption datausing the BET equation.5. Significance and Use5.1 This test method has been found useful for the determi-nation of the specific surface area of catalysts and catalystcarriers in the range from 0.05 to 10 m2/g for materials1This test method is under the jurisdic
12、tion of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.01 on Physical-Chemical Properties.Current edition approved Feb. 1, 2017. Published February 2017. Originallyapproved in 1988. Last previous edition approved in 2012 as D478012). DOI:10.1520/D4780-12R17.2For
13、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,
14、West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World
15、 Trade Organization Technical Barriers to Trade (TBT) Committee.1specification, manufacturing control, and research and devel-opment in the evaluation of catalysts. The determination ofsurface area of catalysts and catalyst carriers above 10 m2/g isaddressed in Test Method D3663.6. Apparatus6.1 Asch
16、ematic diagram of the apparatus is shown in Fig. 1.It may be constructed of glass or of metal and may operatemanually or automatically. It has the following features:6.1.1 Vacuum System, capable of attaining pressures below10-4torr (1 torr = 133.3 Pa). This will include a vacuum gage(not shown in Fi
17、g. 1). Access to the distribution manifold isthrough the valve V.6.1.2 Distribution Manifold, having a volume between 5and 40 cm3(Vd) known to the nearest 0.01 cm3. This volumeis defined as the volume between the stopcocks or valves andit includes the volume within the pressure gage.6.1.3 Constant V
18、olume Gages, capable of measuring 1 to 10torr to the nearest 0.001 torr and 0 to 1000 torr to the nearesttorr (1 torr = 133.3 Pa).6.1.4 Valve (H), from the helium supply to the distributionmanifold.6.1.5 Valve (K), from the krypton supply to the distributionmanifold.6.1.6 Sample Tube(s), with volume
19、 between 5 cm3and 25cm3, depending on the application. The sample tube(s) may beconnected to the distribution manifold with standard taperjoints, glass-to-glass seals, or compression fittings.NOTE 1Modern commercial instruments may employ simple tubeswith volumes outside of this range, and may be ca
20、pable of testing multiplesamples simultaneously rather than separately as stated in 9.1.6.1.7 Dewar Flask(s) for immersion of the sample tube(s) inliquid nitrogen. The nitrogen level should be fixed at a constantheight by means of an automatic level controller or manuallyrefilled to a predetermined
21、mark on the sample tube(s) about 30to 50 mm below the distribution manifold connectors.6.1.8 Thermometer for measuring the temperature of thedistribution manifold (T1(i)orT2(i) in degrees Celsius.(Alternatively, the distribution manifold may be thermostatteda few degrees above ambient to obviate the
22、 necessity ofrecording this temperature.)6.1.9 Heating Mantle(s) or Small Furnace(s) for eachsample tube to allow outgassing samples at elevated tempera-tures.6.1.10 Laboratory Balance with 0.1 mg (107kg) sensitiv-ity.6.1.11 Thermometer for measuring the temperature of theliquid nitrogen bath (Ts(i)
23、 in kelvins. This will preferably bea nitrogen vapor-pressure-thermometer that gives Po,Ndirectlyand has greater precision, or a resistance thermometer fromwhich Po,Nvalues may be derived.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated,
24、it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit it
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