1、Designation: D 3906 03Standard 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 oforiginal adoption or,
2、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 diffraction intensiti
3、es 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 parameterusually within the limi
4、ts of 24.2 and 25.0A(2.42 and 2.50 nm).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 under the peak or th
5、e product of the peak height and thepeak width.1.4 The 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, for example, REY as a
6、 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.1.5.2 The absorption f
7、or 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 safety and health practices
8、 and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods2E 456 Terminology Relating to Quality and Statistics2E 691 Practice for Conducting an Interlaboratory Study to
9、Determine the Precision of a Test Method23. 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 eight peaks is used to
10、give % 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 of manufacture and c
11、ommerce.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 desiccation, sulfur compound
12、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.4.3 Drastic changes
13、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. Theelectron density distribution is dependent upon the extent offilling of pores in the zeolite with guest molecules, and on thenature of t
14、he 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 that couldvary the intensities of the XRD peaks, this XRD me
15、thod will1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.05 on Zeolites.Current edition approved March 10, 2003. Published April 2003. Originallyapproved in 1980. Last previous edition approved in 1997 as D 390697.2An
16、nual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.provide the best determination of relative crystallinity when thereference and sample have a similar history of preparation andcomposition.4.4 Cor
17、rections are possible that can make this XRDmethod accurate for measuring percent zeolite 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 stri
18、p chart re-corder or with computerized data acquisition and reductioncapability, using 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.5.4 Planimeter or Appropriate
19、 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 splitting a large portion of thesample and refere
20、nce 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 breaking up of finecrystals and even destruct
21、ion of zeolite.8. Procedure8.1 Carry out the following steps, 8.2 through 8.5, in anidentical 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 hold atroom temperature and 35 % relative
22、 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 XRDsample holder.8.4 Obtain a first XRD pa
23、ttern 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 the NaYreference pattern so that the stro
24、ng (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. Fig.1 shows such patterns for the refer
25、ence 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 for NaY.)8.6 Obtain a second XRD pattern
26、 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 low level of zeolite samples.8.6.1 The
27、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) peak19.0 to 22.0, (440) peak25.5 to 28.0, (
28、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 provide a background reading oneach side of
29、 the main peak. Within each range the major zeolite peak willbe 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
30、 threeways:9.1.1 By approximating the area under the peak as 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 dig
31、ital integratingsystem (use 9.4 for integrator counts calculation).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 expres
32、sed in terms of counts per second correspondingto full scale 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 peakm
33、aximum. Obtain the width factor, WF, which is the ratio ofthe 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
34、may contain disorder; crystals may exist with a range of unit celldimensions; and diffraction may originate from varying depths below thesample surface, limited by absorption, and related to density of packing ofthe sample.3Available from National Institute of Standards and Technology (NIST), 100Bur
35、eau Dr., Stop 3460, Gaithersburg, MD 20899-3460.D39060329.2.3 The objective of the method, a value for “% XRDintensity/NaY,” is obtained in this step. This involves acomparison of the sums of peak heights (measured abovebackground) from the patterns obtained in Step 8.4. The ratioof these sums must
36、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 summation in Table 1:NOTE 6The 2u value ranges tabulated in Table 1 are appropriate forzeolites with unit
37、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 peaks, 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
38、 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 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
39、 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 rare case when the peaks are doubletsresulting from presence of two zeolites of distinctly differentunit cell parameters. This preferred method is based on eight
40、ofthe most intense diffraction peaks, not because any single peakis more sensitive to details of crystal structure than is the sumof these eight peaks.9.3 Area By Planimeter:Angle (2u)FIG. 1 X-Ray Diffraction Patterns of ASTM Zeolite Samples UpperNaY; LowerCracking Catalyst IntensityD3906033Angle (2
41、u)FIG. 2 NaYComplete Diffractometer Scan IntensityAngle (2u)FIG. 3 XRD ASTM NaY IntensityD39060349.3.1 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 follow
42、ing equation:% XRD intensity/NaY 5SXSR3 100 (2)where:Sx= sum of 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 intens
43、ities (measured abovebackground) by counts from the patterns obtained 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 conditi
44、ons it may be desirable to base thecomparison of zeolite XRD intensity 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 reproduci
45、ble but is not necessarily in closeagreement with the result of 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
46、 ways:9.5.1 From the counts recorded by a digital integratingsystem 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 intens
47、ity values are measured abovebackground. In some cases, as seen 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 t
48、hat apply for the three methods aregiven here.% XRD intensity/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 H
49、X/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” zeolites may have values obtained from Steps9.2, 9.3, or 9.4:% XRDIntensity/NaYNaY, NaX 90 to 105NH4Y 100 to 115REY 25 to 50Ultrastable Y 80 to 959.7 The range given is caused by such factors as silica-alumina ratio, actual cation contents, whi
