ASTM D4365-2013 Standard Test Method for Determining Micropore Volume and Zeolite Area of a Catalyst《测定催化剂微孔体积和沸石面积的标准试验方法》.pdf

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1、Designation: D4365 13Standard Test Method forDetermining Micropore Volume and Zeolite Area of aCatalyst1This standard is issued under the fixed designation D4365; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev

2、ision. 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 totalsurface area and mesopore area. From these results are calcu-lated the zeoli

3、te area and micropore volume of a zeolitecontaining catalyst. The micropore volume is related to thepercent zeolite in the catalyst. The zeolite area, a numberrelated to the surface area within the zeolite pores, may also becalculated. Zeolite area, however, is difficult to intepret inphysical terms

4、 because of the manner in which nitrogenmolecules pack within the zeolite.1.2 The values stated in SI units are to be regarded 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 u

5、se. 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. For a specificprecautionary statement, see Note 3.2. Referenced Documents2.1 ASTM Standards:2D3663 Test Method for S

6、urface Area of Catalysts andCatalyst CarriersD3906 Test Method for Determination of Relative X-rayDiffraction Intensities of Faujasite-Type Zeolite-Containing MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Pra

7、ctice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 mesopore (matrix) area of a catalystthe area deter-mined from the slope of the t-plot.3.1.2 micropore volume of the catalystthe pore volume i

8、npores having radii less than 1 nm, usually associated with thezeolite portion of the catalyst, and determined from theintercept of the t-plot.3.1.3 surface area of a catalystthe total surface of thecatalyst pores. It is expressed in square metres per gram.3.1.4 zeolite area of a catalystthe differe

9、nce between totalsurface area and mesopore area.3.2 Symbols:PH1= initial helium pressure, torrPH2= helium pressure after equilibration, torrSB= slope of BET plot, 11.7IB= intercept of BET plot, 11.7St= slope of t-plot, 11.13It= intercept of t-plot, 11.13TH1= temperature of manifold at initial helium

10、 pressure,CTH2= temperature of manifold after equilibration, CTx(i) = extra volume bulb temperature, CTx(i) = extra volume bulb temperature, KP1(i) = initial N2pressure, torrT1(i) = manifold temperature at initial N2pressure, KT1(i) = manifold temperature at initial N2pressure, CP2(i) = pressure aft

11、er equilibration, torrT2(i) = manifold temperature after equilibration, KT2(i) = manifold temperature after equilibration, CP0(i) = liquid nitrogen vapor pressure, torrTs(i) = liquid nitrogen temperature, KX = relative pressure, P2/P0Vd= volume of manifold, cm3Vx= extra volume bulb, cm3Vs= effective

12、 void volume, cm3Ws= weight of sample, gW1= tare weight of sample tube, gW2= weight of sample + tare weight of tube, gVds= volume of nitrogen in the dead-space, cm3V1= see 11.4.31This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommi

13、ttee D32.01 on Physical-Chemical Properties.Current edition approved April 1, 2013. Published August 2013. Originallyapproved in 1984. Last previous edition approved in 2008 as D4365 95(2008).DOI: 10.1520/D4365-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM C

14、ustomer 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 States1V2= see 11.4.4Vt= see 11.4.5Va= s

15、ee 11.4.7Vm= see 11.8BET(i) = see 11.4.8t(i) = see 11.104. Summary of Test Method4.1 The volume of nitrogen gas adsorbed by the catalyst atliquid nitrogen temperature is measured at various low-pressure levels by the catalyst sample at liquid nitrogentemperature. This is done by measuring pressure d

16、ifferentialsresulting from introducing a fixed volume of nitrogen to thedegassed catalyst in the test apparatus. This procedure is thesame as Test Method D3663, that gives total surface area, butextends the pressure range to permit calculation of microporevolume and matrix surface area, by the t-plo

17、t method. Zeolitearea is the difference between total area and matrix area.5. Significance and Use5.1 This gas adsorption method complements the X-rayprocedure of Test Method D3906. This test method will beuseful to laboratories that do not have X-ray diffractometers.Each test method can be calibrat

18、ed by use of an appropriateseries of mechanical mixtures to provide what may be termedpercent zeolite. If there is disorder in the zeolite, the adsorptionmethod will yield higher values than the X-ray method. Thereverse will be true if some zeolite pores (micropores) areblocked or filled.6. Apparatu

19、s6.1 Aschematic diagram of the apparatus is shown in Fig. 1.It may be constructed of glass or of metal. It has the followingfeatures:6.1.1 Distribution or Dosing Manifold, having a volumebetween 20 and 35 cm3,(Vd), known to the nearest 0.05 cm3.This volume is defined as the volume between the stopco

20、cks orvalves and includes the pressure gage. It is preferred that thisvolume be thermostatted.6.1.2 Vacuum System, capable of attaining pressures below104torr (1 torr = 133.3 Pa). This will include a vacuum gage(not shown in Fig. 1). Access to the distribution manifold isthrough the valve V.6.1.3 Pr

21、essure Sensing Devices or Pressure Transducer,capable of measurements to the nearest 0.1-torr sensitivity inthe range from 0 to 1000 torr (1 torr = 133.3 Pa).NOTE 1See, for example, the article by Joy for a description of aconstant-volume manometer.36.1.4 Valve (H), from the helium supply to the dis

22、tributionmanifold.6.1.5 Value (N), from the nitrogen supply to the distributionmanifold.6.1.6 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.6.1.7 Extra Volume (EV) Bulb, if employed, may be at-tached through

23、valve EV. Its volume (Vx) should be 100 to 150cm3, known to the nearest 0.05 cm3. Vxincludes the volume ofthe stopcock bore in the glass apparatus. It is preferred that thisvolume be held at the same temperature as that of thedistribution manifold.NOTE 2Modern commercial instruments automatically ad

24、just theamounts dosed in order to produce data points at user-selected targetpressures. Hence, the use of an EV bulb is optional. Some instruments cananalyze multiple samples simultaneously and may use sample tubes withvolumes outside of the range specified in this test method.6.2 Sample Tubes, with

25、 volumes from 5 cm3to 25 cm3depending on the application. Markings should be placed onthe sample tubes about 30 to 50 mm below the connectors toindicate the desired liquid nitrogen level if automatic control ofliquid nitrogen level is not available.6.3 Heating Mantles or Small Furnaces.6.4 Dewar Fla

26、sks.6.5 Laboratory Balance, with 0.1 mg (107kg) sensitivity.6.6 Thermometer or Thermocouple, for measuring the tem-perature of the distribution manifold, T1(i)orT2(i), in degreesCelsius.6.6.1 The manifold may be thermostated at a particulartemperature, a few degrees above ambient, to obviate thenece

27、ssity of recording this temperature at each reading.6.7 Thermometer or Thermocouple, for measuring the tem-perature of the liquid nitrogen bath Ts(i) in kelvins from which3Joy, A. S., Vacuum, Vol 3, 1953, p. 254.FIG. 1 Schematic Diagram of Surface Area ApparatusD4365 132P0values may be derived. This

28、 will preferably be a nitrogenvapor-pressure-thermometer, often referred to in a commercialinstrument as a pressure saturation tube, from which P0valuesmay be measured directly with greater precision, or a resis-tance thermometer from which P0values may be derived.6.8 Thermometer or Thermocouple, fo

29、r measuring the tem-perature of the EV bulb, Tx(i), if different from T1(i)orT2(i).7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reage

30、nts of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Helium GasA cylinder of helium gas at least

31、99.9 %pure.7.3 Liquid Nitrogen, of such purity that P0is not more than20 torr above barometric pressure. A fresh daily supply isrecommended.7.4 Nitrogen GasA cylinder of nitrogen gas at least99.9 % pure.8. ProcedureSample Preparation and Degassing8.1 Select a sample tube of the desired size.A5-cm3sa

32、mpletube is preferred for samples not exceeding about 1 g, tominimize the dead-space. However, a 25-cm3sample tube maybe preferred for finely powdered catalysts, to avoid “bumping”when degassing is started.8.2 Fill the sample tube with nitrogen or helium, at baro-metric pressure, after removing air

33、by evacuation. This may bedone on the surface area unit, or on a separate piece ofequipment.8.3 Remove the sample tube from the system, cap, andweigh. Record the weight as W1.8.4 Place the catalyst sample, of which the weight is knownapproximately, into the sample tube. Choose the sample size toprov

34、ide an estimated total sample surface area of 20 to 100 m2.8.5 Attach the sample tube to the apparatus. If other samplesare to be run, attach them at this time to the other ports.8.6 Open the S valves where there are samples.8.7 Slowly open the V valve, monitoring the rate of pressuredecrease to avo

35、id too high a rate, which could lead to excessivefluidization of powdered samples.8.7.1 It may be necessary to close the V valve systemperiodically to protect the vacuum pump from exposure topressures above 0.1 torr for periods of more than 30 s. Closethe valve off for 2 min each time.8.8 Install a

36、heating mantle or furnace around each sampleand raise the temperature to about 300C (573 K).NOTE 3Take special precautions if the moisture content exceedsapproximately 5 % to avoid “bumping” of powdered catalyst, and to avoidsurface area loss by self-steaming. It is recommended that the heating rate

37、not exceed 100C(K)/h under these circumstances.8.9 Continue degassing at about 300C (573 K) for aminimum of 3 h, at a pressure not to exceed 103torr.Overnight degassing is permissible.NOTE 4Zeolite-containing catalysts may contain large quantities ofwater. Pretreatment of the sample in an oven at 40

38、0C in flowing nitrogenfor a couple of hours may be desirable.8.10 Remove the heating mantles, and allow the samples tocool.8.11 Close the EV valve, if open.8.12 Close the S valve.8.13 It is recommended to exercise the option of prelimi-nary degassing on an external unit. In such a case, follow thepr

39、ocedures of 8.4-8.11 and then optionally repeat on thesurface area unit, except that the supplementary degassing timein 8.9 should not exceed 1 h.8.14 If it is desired to weigh the sample after preliminarydegassing on an external unit, backfill with the same gas usedin 8.2 to barometric pressure. Cl

40、ose the S valve. Otherwise, usethe weight obtained in 10.18 and omit 8.15.8.15 Detach the sample tube from the apparatus, recap withthe stopper used previously, and weigh. Record the weight asW2.8.16 Attach the sample tube, uncapped, to an analysis porton the measurement apparatus. Remove the backfi

41、lled gas byevacuation to less than 104torr at room temperature.9. ProcedureDead-Space Determination9.1 From this point on, each sample being tested formicropore volume and surface area must be run on anindividual basis. Thus, each Step 9.2-10.17 must be carried outseparately for each tube in test.9.

42、2 The “dead-space” is the void volume of the chargedsample tube, including the volume within the S valve, when thetube is immersed in liquid nitrogen to the proper depth.NOTE 5The dead-space may be determined after the nitrogenadsorption, if more convenient, so long as adequate degassing precedes it

43、sdetermination. In that case, replace the liquid nitrogen bath after 10.14before proceeding with 9.3-9.9. Then, remove the Dewar flask beforecarrying out 10.15-10.17.9.3 Place a Dewar flask of liquid nitrogen around the sampleand adjust the liquid level to a fixed point on the sample tube.Maintain t

44、his level throughout the test.NOTE 6Some modern commercial instruments do not require manualmaintenance or readjusting of the level of liquid nitrogen during theanalysis. Follow the manufacturers recommendations for operating theparticular instrument used.9.4 Zero the pressure gage.4Reagent Chemical

45、s, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Fo

46、rmulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D4365 1339.5 Admit the helium gas into the system to a pressure of600 to 900 torr by carefully opening the H valve. With H valveclosed, record this pressure, PH1, and the manifold temperature,TH1.9.6 Open the S valve to admit helium t

47、o the sample.9.7 After about 5 min of equilibration, readjust the liquidnitrogen level, and record the pressure, PH2, and the manifoldtemperature, TH2.9.8 Repeat 9.5-9.7 for each sample cell attached to themanifold.9.9 Open all S valves; then slowly open the V valve toremove the helium gas.9.10 When

48、 a pressure less than 0.01 torr has been attained,close the S valve. This operation should take 5 to 10 min.10. ProcedureNitrogen Adsorption10.1 Close the V valve and open the EV valve. (The extravolume bulb should be thermostatted at a particulartemperature, a few degrees above ambient.)10.2 Rechec

49、k the zero setting of the pressure gage.10.3 Admit nitrogen gas, and record the pressure as P1(1)(torr) and the temperature as T1 (1) (degrees Celsius). It isdesirable, but not necessary, to choose P1(1) such that the firstequilibrium adsorption pressure, P2(1) will be about 8 to 15torr, or P2(1)/P0of about 0.01 to 0.02. Record Tx(1). Close theEV valve.10.4 Open the S valve to admit nitrogen to the catalyst.10.5 Allow sufficient time for equilibration, readjusting theliquid nitrogen level when necessary. Equilibrium shall beconsidered as att