ASTM_D_3943_-_10_2015.pdf

Designation:D394310(Reapproved 2015)Standard Test Method forTotal Molybdenum in Fresh Alumina-Base Catalysts1This standard is issued under the fixed designation D3943;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of 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 molybde-num in alumina-base catalysts and has been cooperativelytested at molybdenum concentrations from 8 to 18 weight%,expressed as MoO3.Any component of the catalyst other thanmolybdenum such as iron,tungsten,etc.,which is capable ofbeing oxidized by either ferric or ceric ions after being passedthrough a zinc-amalgam reductor column(Jones reductor)willinterfere.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 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 WaterD7442 Practice for Sample Preparation of Fluid CatalyticCracking Catalysts and Zeolites for ElementalAnalysis byInductively Coupled Plasma Atomic Emission Spectros-copyE173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals(Withdrawn1998)3E507 Test Method for Determination of Aluminum in IronOres by Flame Atomic Absorption Spectrometry3.Summary of Test Method3.1 The catalyst is digested in hot sulfuric acid to dissolvemolybdenum,destroy organic matter,and to expel nitrates ifpresent.The acid solution is diluted and passed through anamalgamated zinc column(Jones reductor)into a receivingflask containing an excess of ferric ammonium sulfate.Thecolumn quantitatively reduces the molybdenum(Mo+6toMo+3)which in turn is reoxidized in the receiving flaskaccording to the reaction:Mo1313Fe13Mo1613Fe12(1)3.2 The ferrous ion produced(three per Mo+3oxidized)istitrated with standard ceric sulfate solution in the presence offerroin indicator.The indicator undergoes a color change(pinkto colorless or very faint blue-green)in the presence of excessceric ion.The amount of Fe+2titrated in the reaction:Fe121Ce14Fe131Ce13(2)is a direct measure of Mo+6concentration.4.Significance and Use4.1 This test method sets forth a procedure by whichcatalyst samples can be compared either on an interlaboratoryor intralaboratory basis.It is anticipated that catalyst producersand users will find this method of value.5.Interferences5.1 Elements such as As,Sb,Cr,Fe,Ti,V,U,or W caninterfere in this analysis.If serious interference occurs,it willbe necessary to isolate the molybdenum from the interferingspecies prior to measurement.5.2 Organics and nitrates can interfere or react with thezinc-amalgam if the sulfuric acid treatment is not properlycarried out as described in 9.1.6.Apparatus6.1 Beakers,250-mL.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 Dec.1,2015.Published December 2015.Originallyapproved in 1980.Last previous edition approved in 2010 as D394310.DOI:10.1520/D3943-10R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 Jones Reductor Column,30-cm long by 2 cm in outerdiameter,with a 100-mL reservoir.4Attach a piece of vinyltubing to the end of the delivery tube long enough to extend tothe bottom of the filtering flask(see Test Method E507).6.3 Vacuum Filtering Flask,heavy-walled,1000-mL.6.4 Buret,50-mL,Class A(0.1-mL divisions).6.5 Stirring Motor,magnetic,and TFE-fluorocarbon-covered stirring bars,7.11 by 14.2 mm.7.Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water conformingto Specification D1193.7.3 Ceric Sulfate,0.10 N standardized