1、Designation: D4642 04 (Reapproved 2016)Standard Test Method forPlatinum in Reforming Catalysts by Wet Chemistry1This standard is issued under the fixed designation D4642; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. 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 platinum innonzeolitic, fresh reforming catalysts containing platinum ast
3、he only precious metal, in the range of concentration of 0.200to 0.700 weight %.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
4、 its use. 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.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE177 Practice for Use of the Te
5、rms Precision and Bias inASTM Test MethodsE288 Specification for Laboratory Glass Volumetric FlasksE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 U.S. Federal Specification:NNN-P-395C Tolerance fo
6、r Class A Pipets33. Summary of Test Method3.1 The ground alumina based reforming catalyst is dis-solved using dilute hydrochloric acid. Stannous chloride isadded to convert the platinum in solution to a yellowish-orange-colored platinum stannous hydrochloride complex. Theabsorbance of the resulting
7、solution is measured comparativelyat 403 nm by spectrophotometry and the platinum content iscalculated from a previously determined value 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
8、-num is supported on an all alumina substrate.44.2 This test method is not intended to cover samplescontaining metals other than platinum. Palladium, rhenium,and rhodium in particular interfere with the spectrophotometricdetermination of platinum.5. Apparatus5.1 Balance, analytical, capable of weigh
9、ing 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, platinum, 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
10、specifiedby Specification E288, 500-mL and 1000-mL.5.8 Funnel, filtering, fluted bowl, 65 mm top diameter, 150mm stem.5.9 Graduated Cylinders, 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, capab
11、le of 1000 6 25C.5.12 Spectrophotometer, capable of measuring absorbancevalues between 200 to 800 nm with a photometric repeatabilityof 60.002 absolute at 1.0 absolute.5.13 Watch Glass, flat, 100 mm.5.14 Watch Glass, ribbed, 65 mm.1This test method is under the jurisdiction of ASTM Committee D32 onC
12、atalysts and is the direct responsibility of Subcommittee D32.03 on ChemicalComposition.Current edition approved Jan. 1, 2016. Published January 2016. Originallyapproved in 1986. Last previous edition approved in 2010 as D464204(2010).DOI: 10.1520/D4642-04R16.2For referenced ASTM standards, visit th
13、e ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Ph
14、iladelphia, PA 19111-5098.4This test method can be extended to spent reforming catalyst by isolating theplatinum by the methods described in “Assay Procedure for Platinum in ReformingCatalysts,” Analytical Chemistry , Vol 32, No. 6, May 1960, p. 646.Copyright ASTM International, 100 Barr Harbor Driv
15、e, PO Box C700, West Conshohocken, PA 19428-2959. United States15.15 Wash Bottle, polyethylene, 500-mL.5.16 Weighing Vial, 25 by 40 mm.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the
16、specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determinat
17、ion.56.2 Purity of WaterUnless otherwise indicated, all refer-ences to water used as a reagent mean deionized or distilledwater conforming to Specification D1193.6.3 Aluminum Chloride SolutionDissolve 453.6 g ofAlCl36H2O in water and dilute to a litre with water.6.4 Aqua RegiaMix three parts concent
18、rated hydrochloricacid with one part concentrated nitric acid.6.5 Formic Acid (HCOOH).6.6 Hydrochloric Acid (HCl), concentrated, specific gravity1.19.6.7 Hydrochloric Acid (HCl) Solution, 18 to 19 volume %or 6 N. Dilute 500 mL of concentrated hydrochloric acid to alitre with water.6.8 Hydrochloric A
19、cid (HCl), 3.7 volume % or 1.2 N. Dilute100 mL of concentrated hydrochloric acid to a litre with water.6.9 Hydrogen Peroxide (H2O2), or chlorine gas.6.10 Nitric Acid (HNO3), concentrated specific gravity 1.42.6.11 Platinum Wire, 99.99 % platinum purity.6.12 Standard Platinum Solutions, approximately
20、 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 hydrochloricacid, cover the beaker using a ribbed watch glass and heat thecontents at 85C. Add additional acid until all of the platinumis
21、 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 dryness at 85C.Wash the watch glass and sides of the beaker with about 20 mLof 6 N hydrochloric acid solution and evaporate to drynessa
22、gain. 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 acid to the sample toreduce any remaining nitric acid. Transfer this solution quan-titatively to a 1000-mL volumetric flask.Add an additi
23、onal 300mL of concentrated hydrochloric acid, dilute to volume withwater and mix thoroughly. Allow the solution to cool to roomtemperature and readjust carefully to volume with water andmix. This stock solution contains approximately 1000 ppm ofplatinum and provides suitable aliquots for platinum st
24、andards.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 stannous chloride solution tothe 500-mL flask. Add sufficient aluminum chloride solution,(approximately 15 mL), to bring the standard to the
25、 samestoichiometric aluminum level as the unknown. Add distilledwater to bring the solution just to the neck of the flask, whichpermits mixing of all components. Prior to taking a portion fora spectrophotometric reading, allow the solution to come toroom temperature, add additional distilled water t
26、o 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 concentrated hydro-chloric acid with warming on a hot plate. Dilute to 1000 mLwith water and mix thoroughly. Filter this solution if it iscloudy.
27、 This solution should be prepared fresh daily.6.14 Water, distilled, reagent.57. Procedure7.1 CalcinationThe platinum level in reforming catalystsis normally reported on a volatile-free basis. The loss onignition (LOI) determination (1000C) is carried outseparately, but weighed out at the same time
28、as the groundsample for digestion. Due to the hygroscopic nature of thesample, weigh by difference from a weighing vial. Weigh intriplicate 3 g 6 0.1-mg samples of reforming catalyst inplatinum or porcelain crucibles, place in a muffle furnace at1000 6 25C, and keep at this temperature for 3 h. Remo
29、vethe crucible from the muffle and transfer to a desiccator, cool,and weigh 1 h after removal from the muffle. The desiccant tobe loaded in the desiccator is freshly regenerated Type 4Amolecular sieves.7.2 DigestionWeigh a ground portion of catalyst into a600-mL beaker to contain 6 to 8 mg platinum
30、(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 hydrochloric acid at 90C. Add 1 to2mLofH2O2or pass chlorine through the solution for 20 minto accelerate the reaction. Cover with a watch glass
31、. 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 water. Ignite the filter paper andredigest the residue in a few millilitres of aqua regia, evaporateto dryness, redissolve in 6 N HCl, evaporat
32、e 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 the very minute trace of aluminathat remains insoluble approaches the colloidal state and interferes in thespectrophotometric measurement. T
33、he insoluble material settles on stand-ing 20 h, but any disturbance of the solution redistributes it. In anephelometric test the filtered solution, after complexing withSnCl22H2O, should show a clarity similar to that of the standard solution.7.3 Color Development of Platinum SolutionComplex thetes
34、t sample contained in the 500-mL flask with 30 mL ofSnCl22H2O solution and add sufficient additional concentrated5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Socie
35、ty, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D4642 04 (2016)2HCl so that the flask contains 175 mL of HCl to equal that usedin the platinum standard
36、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 solutions. In turn, themilligrams and percentage
37、s 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 instrument to the zero baseline. Determine abso
38、rbance with a spectrophotometer at403 nm. It is recommended that a standard be measured andthen a test sample, alternating through the measurements untilthe absorbance has been obtained for all solutions.8. Calculation of Results8.1 Derive from the measurements of the standards anaverage factor in t
39、erms 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 the platinum concentration of the test sample in percent asfollows:A/B 310! (1)where:A = milligrams of platinum found in the sample,
40、andB = weight of volatile-free sample, g.9. Precision and Bias9.1 Test ProgramAn interlaboratory study was conductedin which the weight % platinum (volatile-free basis) wasmeasured in one test material in seven separate laboratories.Practice E691, modified for nonuniform data sets, was fol-lowed for
41、 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 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
42、 two testresults, and S is the appropriate estimate of standard deviation.Definitions and usage are given in Terminology E456 andPractice E177, respectively.Test Result(Consensus Mean)95 % RepeatabilityInterval(Within Laboratory)95 % ReproducibilityInterval(between laboratories)0.578 weight % 0.005
43、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 for compari-son.10. Keywords10.1 platinum; precious-metal; reforming catalyst; spectro-photometricASTM International takes no position res
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