1、Designation: D 3906 03 (Reapproved 2008)Standard Test Method forDetermination of Relative X-ray Diffraction Intensities ofFaujasite-Type Zeolite-Containing Materials1This standard is issued under the fixed designation D 3906; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the 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 relativeX-ray dif
3、fraction intensities of zeolites having the faujasitecrystal structure, including synthetic Y and X zeolites, theirmodifications such as the various cation exchange forms, andthe dealuminized, decationated, and ultrastable forms of Y.These zeolites have cubic symmetry with a unit cell parameterusual
4、ly within the limits of 24.2 and 25.0 (2.42 and 2.50nm).1.2 The samples include zeolite preparations in the variousforms, and catalysts and adsorbents containing these zeolites.1.3 The term “intensity of an X-ray powder diffraction(XRD) peak” is the “integral intensity,” either the area ofcounts und
5、er the peak or the product of the peak height and thepeak width.1.4 This test method provides a number that is the ratio ofintensity of portions of the XRD pattern of the sample tointensity of the corresponding portion of the pattern of areference zeolite, NaY. (Laboratories may use a modified Y orX
6、, for example, REY as a secondary standard.) The intensityratio, expressed as a percentage, is then labeled “% XRDintensity/NaY.”1.5 Under certain conditions such a ratio is the percentzeolite in the sample. These conditions include:1.5.1 The zeolite in the sample is the same as the referencezeolite
7、.1.5.2 The absorption for the X-rays used is the same for thezeolite and the nonzeolite portions of the sample.1.6 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 safe
8、ty and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 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 In
9、terlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 The XRD patterns of the zeolite containing sample andthe reference sample (NaY), are obtained under the sameconditions. If the XRD pattern of the zeolite is sufficientlystrong, a comparison of intensities of e
10、ight peaks is used togive % XRD intensity/NaY. For lower zeolite content intensi-ties of the (533) peak (23.5 with Cu Ka radiation) arecompared to provide “% XRD intensity/NaY (533).”4. Significance and Use4.1 Zeolites Y and X, particularly for catalyst and adsorbentapplications, are a major article
11、 of manufacture and commerce.Catalysts and adsorbents comprising these zeolites in variousforms plus binder and other components have likewise becomeimportant. Y-based catalysts are used for fluid catalytic crack-ing (FCC) and hydrocracking of petroleum, while X-basedadsorbents are used for desiccat
12、ion, sulfur compound removal,and air separation.4.2 This X-ray procedure is designed to monitor these Y andX zeolites and catalysts and adsorbents, providing a numbermore or less closely related to percent zeolite in the sample.This number has proven useful in technology, research, andspecifications
13、.4.3 Drastic changes in intensity of individual peaks in theXRD patterns of Y and X can result from changes of distribu-tion of electron density within the unit cell of the zeolite. The1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of S
14、ubcommittee D32.05 on Zeolites.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 1980. Last previous edition approved in 2003 as D 390603.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
15、al Book 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.electron density distribution is dependent upon the extent offilling of pore
16、s in the zeolite with guest molecules, and on thenature of the guest molecules. In this XRD method, the guestmolecule H2O completely fills the pores. Intensity changesmay also result if some or all of the cations in Y and X areexchanged by other cations.4.3.1 Because of the factors mentioned in 4.3
17、that couldvary the intensities of the XRD peaks, this XRD method willprovide the best determination of relative crystallinity when thereference and sample have a similar history of preparation andcomposition.4.4 Corrections are possible that can make this XRDmethod accurate for measuring percent zeo
18、lite in many specificsituations. These corrections are well known to those skilled inX-ray diffraction. It is not practical to specify those correctionshere.5. Apparatus5.1 X-ray Diffractometer, equipped with a strip chart re-corder or with computerized data acquisition and reductioncapability, usin
19、g copper K-alpha radiation.5.2 Drying Oven, set at 110C.5.3 Hydrator (Glass Laboratory Desiccator), maintained at35 % relative humidity by a saturated solution of salt, such asCaCl26H2O.Angle (2u)FIG. 1 X-Ray Diffraction Patterns of ASTM Zeolite Samples UpperNaY; LowerCracking Catalyst IntensityD 39
20、06 03 (2008)25.4 Planimeter or Appropriate Peak Profile Analysis orDigital Integration SoftwareIf XRD is not equipped withappropriate software data analysis capability.6. Reagents and Materials6.1 NaY Powder and RE Exchanged Y Powder, as referencestandards.37. Sampling7.1 Conduct sampling by splitti
21、ng a large portion of thesample and reference material homogeneously.7.2 Divide the sample and reference finely to permit pack-ing of the materials into XRD sample holders.NOTE 1The best test to determine if grinding is required is to try topack the sample in the holder. Overgrinding can lead to bre
22、aking up of finecrystals and even destruction of zeolite.8. Procedure8.1 Carry out the following steps, 8.2 through 8.5,inanidentical manner for both the sample and the reference mate-rial, NaY.8.2 Place about 3 to5gofthesample in the drying oven at110C for 1 h. Cool the sample in the hydrator and h
23、old atroom temperature and 35 % relative humidity for at least 16 h.NOTE 2Drying, followed by rehydration, results in filling the zeolitepores with water of hydration but without an excess of moisture residingon the surface of the zeolite particles.8.3 Pack the humidity-conditioned sample into an XR
24、Dsample holder.8.4 Obtain a first XRD pattern by scanning over the anglerange from 14 to 35 2u at about 1/min and using otherinstrument parameters best suited to the diffractometer.8.4.1 If a strip chart recorder is used, set the chart drive at 10mm/min. Select the scale factor (amplification) for t
25、he NaYreference pattern so that the strong (533) peak at 23.6 isbetween 50 and 100 % of full scale. For the sample the scalefactor may be reduced (amplification increased) to providereasonable peak heights. If possible the height of the (533)peak for the sample should be at least 10 % of full scale.
26、 Fig.1 shows such patterns for the reference NaY and for azeolite-containing catalyst.8.5 If this first pattern of the sample contains XRD peaks ofsome nonfaujasite components, it must be established whetherthis may cause interference in the following steps. (Fig. 2 is acomplete diffractometer scan
27、for NaY.)8.6 Obtain a second XRD pattern by scanning over a smallangle range at14 /min.NOTE 3Longer scan times will be required for samples having alower content of zeolite. For example 0.02 2u/step for 1 s may beacceptable for a pure NaY while 10 to 20 s counting times per step maybe required for a
28、 low level of zeolite samples.8.6.1 The preferred angle range is from 22.5 to 25 2u, the(533) peak. Fig. 3 shows such a pattern for NaY. If interferencerules out this range, choose for this step (for both the sampleand the reference patterns) one of the following angle ranges:14.0 to 17.0, (331) pea
29、k19.0 to 22.0, (440) peak25.5 to 28.0, (642) peakNOTE 4These ranges in Step 8.6 each are of such width that two ormore zeolite peaks are included. Such wide ranges are specified to allowfor the variation in peak position over the range of unit cell dimensions24.2 to 25.0 (2.42 to 2.50 mm) and to pro
30、vide a background reading on3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.Angle (2u)FIG. 2 NaYComplete Diffractometer Scan IntensityD 3906 03 (2008)3each side of the main peak. Within each range the major zeolite peak wil
31、lbe the desired one. See Appendix X1 of peak positions.9. Calculation9.1 Obtain an integral peak intensity for each of the eightpeaks (measured above background) chosen from the patternsfrom 8.4, for both the sample and reference, in one of threeways:9.1.1 By approximating the area under the peak as
32、 theproduct of peak height and peak width at half height (use 9.2for appropriate area calculations), or9.1.2 By measuring the area under the peak with a planime-ter (use 9.3 for area by planimeter), or9.1.3 From the counts recorded by a digital integratingsystem (use 9.4 for integrator counts calcul
33、ation).9.2 Approximate Area Calculation:9.2.1 A scale factor correction, SFC, is the ratio of the scalefactor used for the sample pattern, SFX, to that used for thereference pattern, SFR. Thus, SFC = SFX/SFR. Scale factors areusually expressed in terms of counts per second correspondingto full scale
34、 on the recorder. They are related inversely toamplification.9.2.2 Measure the width of the (533) or alternative peaksobtained in Step 8.6. The width is measured at half the peakheight, that is, half way between the background and the peakmaximum. Obtain the width factor, WF, which is the ratio ofth
35、e peak width of the sample, WX, to that of the NaY referencematerial, WR. Thus, WF = WX/WR.NOTE 5Peak broadening occurs for a variety of reasons. Pertinent forzeolite are the following: crystals may be of limited size, below 0.2 m;crystals may contain disorder; crystals may exist with a range of uni
36、t celldimensions; and diffraction may originate from varying depths below thesample surface, limited by absorption, and related to density of packing ofthe sample.9.2.3 The objective of the method, a value for “% XRDintensity/NaY,” is obtained in this step. This involves acomparison of the sums of p
37、eak heights (measured abovebackground) from the patterns obtained in Step 8.4. The ratioof these sums must be corrected for difference in scale factor,by use of SFC as determined in Step 9.2.1, and for differencein peak widths, by use of WF as determined in Step 9.2.2. Eightpeaks are included in the
38、 summation in Table 1:NOTE 6The 2u value ranges tabulated in Table 1 are appropriate forAngle (2u)FIG. 3 XRD ASTM NaY IntensityD 3906 03 (2008)4zeolites with unit cell dimensions 24.2 to 25.0 (2.42 to 2.50 nm).NOTE 7If nonzeolite components give XRD peaks interfering withcertain of the tabulated pea
39、ks, these latter peaks should be omitted fromthe sums, both for the sample and for the reference NaY.9.2.4 The equation used is the following:% XRD intensity/NaY 5 SFX 3 WF 3 SX/SR! 3 100 (1)where:SX= sum of peak heights for the sample andSR= sum for the reference NaY.This test method relies on two
40、assumptions, that the peakintensities are properly expressed as the product of peak heightand peak half width, and that the ratio of half widths obtainedfrom one peak, the (533) peak, is applicable to the other sevenpeaks used in the summation. The first of these two assump-tions is invalid in the r
41、are case when the peaks are doubletsresulting from presence of two zeolites of distinctly differentunit cell parameters. This preferred method is based on eight ofthe most intense diffraction peaks, not because any single peakis more sensitive to details of crystal structure than is the sumof these
42、eight peaks.9.3 Area By Planimeter:9.3.1 Obtain a value for “% XRD intensity/NaY” by com-paring the sums of integrated peak intensities (measured abovebackground) by planimeter from the patterns obtained in 8.4(see Note 7). Use the following equation:% XRD intensity/NaY 5SXSR3 100 (2)where:Sx= sum o
43、f integral peak intensities for the sample, andSr= sum of the integral peak intensities for the referenceNaY.9.4 Integrator Counts Calculation:9.4.1 Obtain a value for “% XRD intensity/NaY” by com-paring the sums of integrated peak intensities (measured abovebackground) by counts from the patterns o
44、btained in 8.4 (seeNote 7). Use the following equation:% XRD intensity/NaY 5SxSr3 100 (3)where:Sx= sum of integral peak intensities for the sample, andSr= sum of the integral peak intensities for the referenceNaY.9.5 Under certain conditions it may be desirable to base thecomparison of zeolite XRD i
45、ntensity on a single peak ratherthan on eight peaks. This is the case when the pattern from thesample is very weak so that only the (533) peak, for example,can be measured. The result of such a single-peak comparisonmay be quite reproducible but is not necessarily in closeagreement with the result o
46、f the eight-peak method. For thispurpose data on the diffraction patterns obtained in Step 8.6 areused. Peak intensity of the (533) peak (or alternative peak) ofStep 8.6 is measured for both the sample and the referenceNaY in one of three ways:9.5.1 From the counts recorded by a digital integratings
47、ystem used while obtaining the pattern of Step 8.6;9.5.2 By measuring the area under the peak with a planime-ter;9.5.3 By approximating the area under the peak as theproduct of peak height and peak half width.9.5.4 In all cases the intensity values are measured abovebackground. In some cases, as see
48、n in Fig. 3, a weak zeolitediffraction peak, (622), is present at 0.25 deg above the (533)peak, and for convenience should be included when measuringthe intensities by either of the first two methods described inthis step. The equations that apply for the three methods aregiven here.% XRD intensity/
49、NaY 533! 5 100 3 CX/CR! (4)where:CX= peak for the sample and,CR= reference NaY.% XRD intensity/NaY 533! 5 100 3 SFC 3 AX/AR! (5)where:AX= area under the peak for the sample andAR= reference, NaY.% XRD intensity/NaY 533!5100 3 SFC 3 WF 3 HX/HR! (6)where:HX= height of the peak in the pattern of the sample andHR= peak in the pattern of the reference NaY.If some diffraction peak other than (533) is used in Step 8.6,insert the designation of that alternative peak, as (331), (440),or (642), in place of (533) in the preceding equations.9.6 “Pure”
