1、Designation: D 6761 07Standard Test Method forDetermination of the Total Pore Volume of Catalysts andCatalyst Carriers1This standard is issued under the fixed designation D 6761; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the totalpore volume of catalysts and catalyst carriers, that is
3、, thevolume of pores having pore diameter between approximately14 m and 0.4 nm (4 ).1.2 This test method involves hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user
4、 of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazard statements are given in Section 8. Warningstatements are given in 9.1.4, 9.1.7, and 9.1.11.2. Referenced Documents2.1 ASTM Standards:2D 3766 T
5、erminology Relating to Catalysts and CatalysisE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to Quality and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3
6、.1.1 particle volumethe volume of a particle includingpores into which mercury cannot penetrate at ambient pressure(smaller than approximately 14 m diameter pore mouth).3.1.2 true volumethe volume of a particle, includingpores, into which helium cannot penetrate (smaller than aboutapproximately 0.4
7、nm (4 ) diameter pore mouth).3.1.3 Other definitions and terms used in this test methodare defined in Terminology D 3766.3.2 Symbols for Mercury Intrusion:W = mass of sampleWc= mass of sealed empty sample cellW8C= mass of sealed sample cell filled with mercuryWs= mass of sealed sample cell with samp
8、leW8S= mass of sealed sample cell with sample filledwith mercuryVHgC= volume of mercury in empty sample cell (volumeof sample cell)VHgS= volume of mercury in cell with sampleVSHg= sample volume, cm3VHg= specific sample volumeVP= particle volumeWb= weight mercury reservoir after filling burette withs
9、ampleWb8= mass of mercury reservoir after filling burettewithout sample3.3 Symbols for Helium Pycnometry:VC= volume of sample cell and associated tubing, cm3VR= reference volume, cm3VSHe= sample volume, cm3VCyl= volume of calibration cylinder, cm3VSTD= volume of calibration standard, cm3VHe= specifi
10、c sample volumeP81= pressure in empty sample cell, psig or pascalsP82= pressure in empty sample cell, after the referencevolume has been included in the system, psig orpascalsP1= pressure in sample cell with sample or calibrationstandard before the reference volume has beenincluded in the system, ps
11、ig or pascalsP2= pressure with sample or calibration standard inthe sample cell, after the reference volume hasbeen included in the system, psig or pascals1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.02 on Physical
12、-Mechanical Properties.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 2002. Last previous edition approved in 2004 as D 676104a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
13、of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.W1= tare weight of sample cup, gW2= mass of sample + tare weight of sample cup, gW3=
14、 mass of sample, gP.V. = pore volume4. Summary of Test Method4.1 The total pore volume of a catalyst or catalyst carrier isdetermined as the difference between the particle volume andthe true volume, measured by mercury intrusion and heliumpycnometry, respectively. The particle volume is determinedb
15、y mercury intrusion at ambient pressure and the true volumeis determined by helium displacement at pressures aboveambient.5. Significance and Use5.1 This test method provides for the measurement ofvolume of pores that are in the range of catalytic importanceand possibly for adsorption processes. Thi
16、s test method re-quires the use of mercury in order to perform the measure-ments.6. Apparatus6.1 For Mercury Intrusion:6.1.1 Chamber, capable of holding the sample cell (com-monly referred to as a penetrometer), which contains thesample. This chamber must be capable of being evacuated andcontain eno
17、ugh mercury to fill the penetrometer.6.1.2 Glass Sample Cell (penetrometer), having a wide baseand narrow bore stem. If the sample is powder, the penetrom-eter should have a provision in the base to prevent fine particlesfrom passing into the stem when the cell is evacuated. Thepenetrometer must hav
18、e the capability of being sealed.6.1.3 Vacuum Pump, capable of attaining pressures of lessthan 0.05 torr.6.1.4 Valve, for choosing vacuum and vent, for evacuationof the sample cell and filling the sample cell, respectively.6.1.5 Valve, for rapid evacuation or venting of the system.6.1.6 Valve, for c
19、ontrolled evacuation or venting.6.1.7 Cold Trap, or other method or device to preventmercury vapor from being vented into the laboratory throughthe vacuum pump and to prevent contaminants from enteringthe vacuum pump.6.1.8 Pressure-Measuring Device, capable of reading in therange 0 to 1000 torr or h
20、igher.6.1.9 Balance, measuring to the nearest 1 mg (60.001 g).6.2 For Mercury Intrusion with a BuretteA schematicdiagram of the burette is shown in Fig. 1. It has the followingfeatures:6.2.1 Glass Sample Cell, with a needle valve suitable forhandling mercury. The tip, which is submerged in the mercu
21、ryreservoir, should be narrow enough so as to prevent drops ofmercury from becoming lost if the reservoir is removed forweighing.6.2.2 Burette, a calibrated narrow bore tube ending in acurved tip in the sample cell to prevent fine particles frompassing into the burette. There is a clear mark on the
22、burette at23 cm above the curved tip.6.2.3 Manifold, with a splash bulb and appropriate needlevalves for choosing either vacuum or vent.6.2.4 Mercury Reservoir with Lid, capable of containing theamount of mercury necessary to fill the sample cell and burettewhile the tip of the sample cell valve is
23、still submerged inmercury. A weighing bottle of 5 cm diameter and 3 cm heightis suitable.6.2.5 Vacuum Pump, capable of attaining pressures of 0.05torr.6.2.6 Cold Trap, or other method or device to preventmercury vapor from being vented into the laboratory throughthe vacuum pump and to prevent contam
24、inants from enteringthe vacuum pump.6.3 For Helium PycnometryA schematic diagram of thepycnometer apparatus is shown in Fig. 2. It should be con-structed from metal and have the following features:6.3.1 Sample Cell, having a volume suitable for the desiredsample size and calibrated to the nearest 0.
25、1 cm3. This volumeis indicated in Fig. 2.6.3.2 Reference Volume (VR), a precisely calibrated volumeknown to the nearest 0.02 cm3.6.3.3 Pressure Transducer, (0 to 25 psig or 0 to 172.3 kPa)with minimum volume displacement and linear within 0.1 %.FIG. 1 Schematic Diagram of BuretteFIG. 2 Pycnometer Ap
26、paratusD67610726.3.4 Pressure Relief Valve, set to 25 psig (172.3 kPa), toavoid overpressurization of the transducer.6.3.5 Filter, to prevent powder from contaminating thepressure transducer.6.3.6 Input Flow Control Valves, to control pressurization.6.3.7 Output Flow Control Valves, to vent the gas.
27、6.3.8 Valve, to connect the reference volume to the samplecell.6.3.9 Non-Porous Calibration Standard, (preferably stain-less steel) of known volume which fills14 to23 of the samplecup.6.3.10 Digital Meter, for reading the pressure to 0.001 psig(6.89 Pa) from the transducer.6.3.11 Sample Cell Cover,
28、with O-ring seal.7. Reagents7.1 For Mercury Intrusion:7.1.1 Mercury, triply distilled.7.2 For Helium Pycnometry:7.2.1 Helium Gas, a cylinder of helium gas at least 99.9 %pure, with regulator.8. Hazards8.1 Samples that have been exposed to mercury are danger-ous. Apply the precautions given by the fo
29、llowing:8.1.1 Mercury is a hazardous substance that can causeillness and death. Mercury can also be absorbed through theskin; avoid direct contact.8.1.2 Always store in closed containers to control its evapo-ration, and use it only in well-ventilated rooms.8.1.3 Wash hands immediately after any oper
30、ation involvingmercury.8.1.4 Exercise extreme care to avoid spilling mercury. Cleanup spills immediately using procedures recommended explic-itly for mercury.8.1.5 Recycling of waste mercury is recommended and to beconducted in accordance with local government hazardouswaste regulations. Disposal of
31、 waste mercury and mercurycontaminated materials should be performed as mandated bylocal government hazardous waste regulations.9. Procedure9.1 For Mercury Intrusion Instruments:9.1.1 Weigh the empty penetrometer with sealing device inplace (WC).9.1.2 Place the empty penetrometer in the low pressure
32、 portof the instrument, seal it, and follow the manufacturersrecommendations for evacuating the penetrometer and subse-quently filling it with mercury.9.1.3 When the penetrometer is completely filled withmercury, follow the manufacturers recommendations forbringing the low pressure port to atmospher
33、ic pressure.9.1.4 When the low pressure port is again at atmosphericpressure, unseal the penetrometer and remove it from the lowpressure port. (WarningAs the penetrometer is removedfrom the low pressure port, be sure to tilt the bulb end of thepenetrometer down and the stem up, so mercury does not s
34、pillfrom the open stem end.)9.1.5 Weigh the mercury-filled penetrometer using an ana-lytical balance, and record this weight as (W8C). Empty thepenetrometer, dispose of the mercury in an approved container,and clean the penetrometer.9.1.6 Weigh the sample using an analytical balance. Recordthis as (
35、W).9.1.7 Hold the penetrometer with the stem down and care-fully pour the sample into the bulb. (WarningWhen pouringpowders into the bulb, place your finger over the stem openingin the center of the bulb so that powder does not enter the stem.Large granules or chunks may be loaded with forceps. Touc
36、h-ing such pieces with the fingers should be avoided as skin oilsmay be transferred that can slightly alter the results or createevacuation problems.)9.1.8 Seal the penetrometer, being careful to avoid usingexcessive sealing grease.9.1.9 Weigh the sealed penetrometer with the sample usingan analytic
37、al balance. Record this weight as (Ws).9.1.10 Place the penetrometer assembly with the sample inthe low pressure port of the instrument, seal it, and follow themanufacturers recommendations for evacuating the penetrom-eter and performing a low pressure analysis.9.1.11 When the low pressure run is co
38、mplete, bring the lowpressure chamber back to atmospheric pressure and follow themanufacturers recommendations for removing the penetrom-eter from the low pressure port. (WarningAs the penetrom-eter is removed from the low pressure port, be sure to tilt thebulb end of the penetrometer down and the s
39、tem end up, somercury does not spill from the open stem end.)9.1.12 Weigh the sealed penetrometer with sample and filledwith mercury using an analytical balance. Record this weightas (W8S).9.2 For Mercury Intrusion Using the Burette Method:9.2.1 Place a coolant (liquid nitrogen or dry ice-acetonemix
40、ture) around the cold trap.9.2.2 Close the vent valve (A) and the sample cell valve (C),and evacuate the burette by opening the vacuum valve (B).9.2.3 Slowly open the sample cell valve and allow mercuryto fill the sample cell and the burette. Close the sample cellvalve (C) when the mercury level is
41、1 to 2 cm above the 23 cmmark. Open the vent valve (A) to allow ambient pressure in theburette. Adjust the mercury level in the burette to the 23 cmmark by slowly draining mercury via the sample cell valve (C)into the mercury reservoir.9.2.4 Place a lid on the mercury reservoir and weigh it usingan
42、analytical balance (Wb8).9.2.5 Drain the mercury from the burette and the sample cellinto the mercury reservoir and close the sample cell valve (C).9.2.6 Weigh the catalyst sample using an analytical balanceand record this weight as (W). Place this sample in the samplecell. Connect the sample cell t
43、o the burette and place themercury reservoir under the sample cell with the tip of thesample cell valve (C) submerged in mercury.9.2.7 Evacuate the burette and sample cell with sample byclosing the vent valve (A) and slowly opening the vacuumvalve (B) in order to prevent fine particles from entering
44、 intothe burette.D67610739.2.8 Allow the sample to degas at 0.05 torr or lower for aminimum of 30 min before filling with mercury.9.2.9 Repeat steps 9.2.2 through 9.2.4 giving the weight ofthe mercury reservoir (Wb).9.2.10 Drain the mercury from the burette and the samplecell into the mercury reserv
45、oir, taking care that afterwards noparticles of the sample are floating on the mercury in thereservoir.9.3 For Helium Pycnometry:9.3.1 Calibration ProcedureTo determine the cell andreference volumes of the pycnometer.9.3.1.1 Place an empty sample cup in the sample cell holderand seal according to th
46、e manufacturers suggested procedure.9.3.1.2 Open the output valves and zero the output display.9.3.1.3 Turn the selector valve to exclude the referencevolume.9.3.1.4 Close the vent valve.9.3.1.5 Open the input flow control valve and pressurize thesample cell to between 15 and 19 psig (103.4 and 130.
47、9 kPa)using the input valve to control the rate of pressurization. Whenthe desired pressure is reached, close the input valve to stop theflow of gas into the sample chamber.9.3.1.6 Record the pressure on the digital display. This valueis P81.9.3.1.7 Turn the selector valve to include the referencevo
48、lume.9.3.1.8 Record the displayed pressure reading as P82.9.3.1.9 Vent the pressure using the vent valve.9.3.1.10 Place the calibration standard cylinder into thesample cup and repeat steps 9.3.1.2 through 9.3.1.9, recordingthe pressure in 9.3.1.6 as P1and the pressure in 9.3.1.8 as P2.9.3.1.11 Calc
49、ulate the reference volume (VR) and the cellvolume (VC) as follows:VR5Vcyl1P81/ P82! 2 121P1/P2! 2 1(1)Vc5VRP81/P82! 2 1(2)9.3.2 Sample Preparation Procedure:9.3.2.1 Weigh the empty sample cup and record as W1.9.3.2.2 Place enough sample in the sample cup to fill it to aminimum of14 capacity, place in the sample cell holder, andseal according to the manufacturers directions.9.3.2.3 Close the input valve and open the output valve.9.3.2.4 Turn the selector valve to include VR.9.3.2.5 Completely open the output valve.9.3.2.6 Open the input valve and adjust the inp
