1、Designation: D 4642 04Standard Test Method forPlatinum in Reforming Catalysts by Wet Chemistry1This standard is issued under the fixed designation D 4642; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 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 platinum innonzeolitic, fresh reforming catalysts containing platinum asthe only preciou
3、s metal, in the range of concentration of 0.200to 0.700 weight %.1.2 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 determine the appl
4、ica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 288 Specification for Laboratory Glass Volumetric FlasksE 456 Terminology Relating to Quality
5、 and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 U.S. Federal Specification:NNN-P-395C Tolerance for Class A Pipets33. Summary of Test Method3.1 The ground alumina based reforming catalyst is dis-solved using dilute hydrochloric acid
6、. Stannous chloride isadded to convert the platinum in solution to a yellowish-orange-colored platinum stannous hydrochloride complex. Theabsorbance of the resulting solution is measured comparativelyat 403 nm by spectrophotometry and the platinum content iscalculated from a previously determined va
7、lue for the absorp-tivity.4. Significance and Use4.1 This test method provides a means of determining theplatinum content of fresh reforming catalysts where the plati-num is supported on an all alumina substrate.44.2 This test method is not intended to cover samplescontaining metals other than plati
8、num. Palladium, rhenium,and rhodium in particular interfere with the spectrophotometricdetermination of platinum.5. Apparatus5.1 Balance, analytical, capable of weighing to the nearest0.1 mg.5.2 Beakers, 250-mL, tall form and 600-mL.5.3 Cells, spectrophotometer, 1.0 cm, matched.5.4 Crucibles, platin
9、um, or porcelain, 50-mL.5.5 Desiccator, vacuum.5.6 Filter Paper, fine, ashless, slow filtering, 12.5 cm orequivalent.5.7 Flasks, volumetric, conforming to tolerances specifiedby Specification E 288, 500-mL and 1000-mL.5.8 Funnel, filtering, fluted bowl, 65 mm top diameter, 150mm stem.5.9 Graduated C
10、ylinders, 10-mL, 25-mL, 50-mL, 250-mL.5.10 Pipets, conforming to tolerances specified by FederalSpecification NNN-P-395C, 5-mL, 10-mL, 15-mL.5.11 Muffle Furnace, capable of 1000 6 25C.5.12 Spectrophotometer, capable of measuring absorbancevalues between 200 to 800 nm with a photometric repeatability
11、of 60.002 absolute at 1.0 absolute.5.13 Watch Glass, flat, 100 mm.5.14 Watch Glass, ribbed, 65 mm.5.15 Wash Bottle, polyethylene, 500-mL.5.16 Weighing Vial,25by40mm.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall
12、reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.03 on ChemicalComposition.Current edition approved
13、 April 1, 2004. Published April 2004. Originallyapproved in 1986. Last previous edition approved in 1998 as D 464292(1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, re
14、fer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-50984This test method can be extended to spent reforming catalyst by isolating theplatinum by the methods described
15、in Analytical Chemistry, Vol 32, No. 6, May1960, p. 646, “Assay Procedure for Platinum in Reforming Catalysts.”1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where such specifications are available. Other grades may beused, provided
16、 it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.56.2 Purity of WaterUnless otherwise indicated, all refer-ences to water used as a reagent mean deionized or distilledwater conforming to Specification D 1193.
17、6.3 Aluminum Chloride SolutionDissolve 453.6 g ofAlCl36H2O in water and dilute to a litre with water.6.4 Aqua RegiaMix three parts concentrated hydrochloricacid with one part concentrated nitric acid.6.5 Formic Acid (HCOOH).6.6 Hydrochloric Acid (HCl), concentrated, specific gravity1.19.6.7 Hydrochl
18、oric Acid (HCl) Solution, 18 to 19 volume %or 6 N. Dilute 500 mL of concentrated hydrochloric acid to alitre with water.6.8 Hydrochloric Acid (HCl), 3.7 volume % or 1.2 N.Dilute 100 mL of concentrated hydrochloric acid to a litre withwater.6.9 Hydrogen Peroxide (H2O2), or chlorine gas.6.10 Nitric Ac
19、id (HNO3), concentrated specific gravity1.42.6.11 Platinum Wire, 99.99 % platinum purity.6.12 Standard Platinum Solutions, approximately 1 mgplatinum per mL. Weigh approximately 1 g 6 0.1 mg ofplatinum wire into a 250-mL tall form beaker. Add 7 mL ofconcentrated nitric acid, 21 mL of concentrated hy
20、drochloricacid, cover the beaker using a ribbed watch glass and heat thecontents at 85C. Add additional acid until all of the platinumis dissolved. Evaporate the resulting chloroplatinic acid solu-tion to a moist salt. Dissolve this material in 20 mL of 6 Nhydrochloric acid solution and evaporate to
21、 dryness at 85C.Wash the watch glass and sides of the beaker with about 20 mLof 6 N hydrochloric acid solution and evaporate to drynessagain. Cool, wash the watch glass and sides of the beaker withabout 20 mL of 6 N hydrochloric acid and dissolve the residuein the beaker. Add a few drops of formic a
22、cid to the sample toreduce any remaining nitric acid. Transfer this solution quan-titatively to a 1000-mL volumetric flask. Add an additional 300mL of concentrated hydrochloric acid, dilute to volume withwater and mix thoroughly. Allow the solution to cool to roomtemperature and readjust carefully t
23、o volume with water andmix. This stock solution contains approximately 1000 ppm ofplatinum and provides suitable aliquots for platinum standards.Transfer aliquots of 5 mL, 10 mL, and 15 mL, respectively, to3 clean 500-mL volumetric flasks. Add 175 mL of concentratedhydrochloric acid, and 30 mL of st
24、annous chloride solution tothe 500-mL flask. Add sufficient aluminum chloride solution,(approximately 15 mL), to bring the standard to the samestoichiometric aluminum level as the unknown. Add distilledwater to bring the solution just to the neck of the flask, whichpermits mixing of all components.
25、Prior to taking a portion fora spectrophotometric reading, allow the solution to come toroom temperature, add additional distilled water to adjust to thevolumetric mark and mix the solution thoroughly.6.13 Stannous Chloride ReagentDissolve 280 g of stan-nous chloride (SnCl22H2O) in 500 mL of concent
26、rated hydro-chloric acid with warming on a hot plate. Dilute to 1000 mLwith water and mix thoroughly. Filter this solution if it iscloudy. This solution should be prepared fresh daily.6.14 Water, distilled, reagent.57. Procedure7.1 CalcinationThe platinum level in reforming catalystsis normally repo
27、rted on a volatile-free basis. The loss onignition (LOI) determination (1000C) is carried out sepa-rately, but weighed out at the same time as the ground samplefor digestion. Due to the hygroscopic nature of the sample,weigh by difference from a weighing vial. Weigh in triplicate 3g 6 0.1-mg samples
28、 of reforming catalyst in platinum orporcelain crucibles, place in a muffle furnace at 1000 6 25C,and keep at this temperature for 3 h. Remove the crucible fromthe muffle and transfer to a desiccator, cool, and weigh 1 h afterremoval from the muffle. The desiccant to be loaded in thedesiccator is fr
29、eshly regenerated Type 4A molecular sieves.7.2 DigestionWeigh a ground portion of catalyst into a600-mL beaker to contain 6 to 8 mg platinum (for example, a0.5 weight % platinum catalyst requires 1.2 to 1.6 g 6 0.1 mg).After weighing, perform a digestion in a 600-mL beakercontaining 150 mL of 6 N hy
30、drochloric acid at 90C. Add 1 to2mLofH2O2or pass chlorine through the solution for 20 minto accelerate the reaction. Cover with a watch glass. Afterseveral hours heating at 85C, only a trace of residue (Al2O3)remains. Dilute this solution and filter into a 500-mL flask, andwash the paper with hot wa
31、ter. Ignite the filter paper andredigest the residue in a few millilitres of aqua regia, evaporateto dryness, redissolve in 6 N HCl, evaporate to dryness,redissolve in 6 N HCl, and filter into the main solution. Thissolution is now ready to complex with SnCl22H2O.NOTE 1Filtration is necessary, since
32、 the very minute trace of aluminathat remains insoluble approaches the colloidal state and interferes in thespectrophotometric measurement. The insoluble material settles on stand-ing 20 h, but any disturbance of the solution redistributes it. In anephelometric test the filtered solution, after comp
33、lexing withSnCl22H2O, should show a clarity similar to that of the standard solution.7.3 Color Development of Platinum SolutionComplex thetest sample contained in the 500-mL flask with 30 mL ofSnCl22H2O solution and add sufficient additional concentratedHCl so that the flask contains 175 mL of HCl t
34、o equal that usedin the platinum standard in 6.12. Adjust the solution to thevolumetric mark with distilled water and mix. Run the set ofthree standard solutions prepared in 6.12 with the samplesolutions. These standards provide the factor to be applied tothe absorbance readings of the sample soluti
35、ons. In turn, themilligrams and percentages of platinum are obtained. Thereadings should be taken the day following color development.With a typical set of readings the cells are first filled with areference solution containing an exact mixture of the reagentsomitting only platinum. Adjust the instr
36、ument to the zero baseline. Determine absorbance with a spectrophotometer at 4035Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for Labo
37、ratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D4642042nm. It is recommended that a standard be measured and then atest sample, alternating through the measurements until theabsorbance
38、 has been obtained for all solutions.8. Calculation of Results8.1 Derive from the measurements of the standards anaverage factor in terms of milligrams of platinum per absor-bance unit. Then, use this factor to convert the absorbancevalues for the test sample into milligrams of platinum. Calcu-late
39、the platinum concentration of the test sample in percent asfollows:A/B 3 10! (1)where:A = milligrams of platinum found in the sample, andB = weight of volatile-free sample, g.9. Precision and Bias9.1 Test ProgramAn interlaboratory study was conductedin which the weight % platinum (volatile-free basi
40、s) wasmeasured in one test material in seven separate laboratories.Practice E 691, modified for nonuniform data sets, was fol-lowed for the data reduction. Analysis details are in theresearch report.69.2 PrecisionPairs of test results obtained by a proceduresimilar to that described in the study are
41、 expected to differ inabsolute value by less than 2.772 S, where 2.772 S is the 95%probability interval limit on the difference between two testresults, and S is the appropriate estimate of standard deviation.Definitions and usage are given in Terminology E 456 andPractice E 177, respectively.Test R
42、esult(Consensus Mean)95 % RepeatabilityInterval(Within Laboratory)95 % ReproducibilityInterval(between laboratories)0.578 weight % 0.005 weight %(0.93 PCT of mean)0.013 weight %(2.31 PCT of mean)9.3 BiasThe test method described is without known biassince there are no reference standards available f
43、or compari-son.10. Keywords10.1 platinum; precious-metal; reforming catalyst;spectrophotometricASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determina
44、tion of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or with
45、drawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that you
46、r comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (sing
47、le or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D32-1035.D4642043
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