1、Designation: D 3943 04Standard Test Method forTotal Molybdenum in Fresh Alumina-Base Catalysts1This standard is issued under the fixed designation D 3943; 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 molybde-num in alumina-base catalysts and has been cooperativelytested at molybdenum con
3、centrations 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 This stan
4、dard 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 A
5、STM Standards:2D 1193 Specification for Reagent WaterE 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals3E 507 Test Method for Aluminum in Iron Ores by AtomicAbsorption Spectroscopy3. Summary of Test Method3.1 The catalyst is digested in hot sulfuric acid
6、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+
7、3) which in turn is reoxidized in the receiving flaskaccording to the reaction:Mo131 3Fe1 3 Mo1 61 3Fe1 2(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 colorl
8、ess or very faint blue-green) in the presence of excessceric ion. The amount of Fe+2titrated in the reactionFe1 21 Ce1 4 Fe1 31 Ce1 3(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 in
9、terlaboratoryor 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 fr
10、om 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.6.2 Jones Reductor Column, 30-cm long by 2 cm in outerdiameter, with a 10
11、0-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 E 507).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-fluoroc
12、arbon-covered stirring bars, 7.11 by 14.2 mm (516 by 1916 in.).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 April 1, 2004. Published April 2004. Originallyapproved
13、 in 1980. Last previous edition approved in 2000 as D 394300.2For 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.
14、3Withdrawn.4The sole source of supply of the apparatus known to the committee at this timeis Part No. 8035-J10 from Thomas Scientific, 99 High Hill Rd. at 295, Swedesboro,NJ 08085. If you are aware of alternative suppliers, please provide this informationto ASTM International Headquarters. Your comm
15、ents will receive careful consid-eration at a meeting of the responsible technical committee,1which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused
16、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 i
17、s 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 D 1193.7.3 Ceric Sulfate, 0.10 N standardized using sodium mo-lybda
18、te following the procedure given in Annex A2.7.4 Ferric Ammonium Sulfate SolutionFeNH4(SO4)212H2ODissolve 200 g of FeNH4(SO4)212 H2O in 1000 mLof water containing 20 mL of concentrated sulfuric acid. Addpotassium permanganate solution dropwise until a pink colorpersists for 1 min.7.5 Ferroin Indicat
19、or, 0.025 M solution of 1, 10-phenanthroline ferrous sulfate complex.7.6 Hydrocholoric Acid (HCl), concentrated.7.7 Jones Reductor Amalgam.7.8 Mercuric Chloride (HgCl2) Solution, approximately2 %. Dissolve 10 g of mercuric chloride (HgCl2) in water.Transfer to a 500mL volumetric flask, dilute to vol
20、ume, andmix.7.9 Molybdenum Standard SolutionDissolve 1.0 g,weighed to the nearest 0.1 mg, of sodium molybdate dihydrate(Na2MoO42H2O) in water containing 10 mL of H2SO4,transfer to a 1-L volumetric flask, dilute to volume, and mix(1 mL = 0.5948 mg MoO3).7.10 Phosphoric Acid (H3PO4), concentratedMix 1
21、30mL of concentrated H2SO4with 250 mL of water. Add the acidslowly with constant stirring. Add 140 mL of concentratedH3PO4and 15 mL of a saturated solution ofMnSO4(approximately 60 g/100 mL). Dilute to 1000 mL withwater.7.11 Potassium Permanganate (KMnO4), approximately0.1 M solution.7.12 Sulfuric A
22、cid (H2SO4), concentrated, 1 + 1 and1 + 19, dilutions with water, corresponding to 18 and 1.8 Nsolutions, respectively. Cautiously add the concentrated sulfu-ric acid to the water, mix well, and allow to cool.7.13 Sulfuric Acid (H2SO4), dilute, 1 + 99, warm, dilutionswith water, corresponding to 0.1
23、8 N solution. Cautiously addthe concentrated sulfuric acid to the water and mix well.7.14 Zinc Metal, 20 mesh, low iron content.8. Sampling8.1 The selection of a representative analytical sample fromthe bulk material is outside the scope of the present method. Itis presumed that parties using this t
24、est method for comparisonpurposes will have agreed on the selection of an analyticalsample which is appropriate to their needs.8.2 Pulverize the analytical sample to pass a 150-m (No.100) sieve. Ignite the pulverized sample for 30 min at 550C ina muffle furnace. Allow to cool in a desiccator.9. Proc
25、edure9.1 Transfer a 0.75-g specimen, weighed to the nearest 1mg, into a 250-mL beaker. Add 20 mL of 1 + 1 H2SO4solutionand heat to fumes on a hot plate. Cool, rinse down with 10 mLof water and take to fumes again. Cool, add 100 mL of waterand heat to dissolve. Cool to room temperature.9.2 Activate t
26、he Jones reductor by passive five 25-mLportions (1 min/25 mL of solution passed) of the 1 + 19H2SO4through the column, using slight vacuum. Do not allow theamalgam to become exposed to air. Test the column by passinga blank of 25 mL of 1 + 19 H2SO4through the reductor into areceiver containing 15 mL
27、 of ferric ammonium sulfate solu-tion. Add 2 to 3 drops of ferroin indicator and 10 mL ofconcentrated H3PO4and titrate with 0.1 N ceric sulfate solutionuntil the pink indicator color completely disappears and isreplaced by a colorless to faint blue green color which persistsfor at least 15 s. If mor
28、e than 1 or 2 drops of ceric sulfatesolution are required, repeat the washing and testing until asuitable blank is obtained.9.3 Pass the sample through the reductor into a receivercontaining 25 mL of ferric ammonium sulfate solution and 10mL of the concentrated H3PO4, using slight vacuum. Keep theti
29、p of the reductor (extended by a piece of vinyl tubing) belowthe surface of the solution in the receiver.9.4 Rinse the reductor with five 25-mL portions of 1 + 19H2SO4, adding the washings to the receiver. Titrate the reducediron solution in the receiver immediately with 0.1 N cericsulfate solution
30、using 2 to 3 drops of ferroin indicator. The faintblue-green color developed at the end point should persist for15 s.10. Calculation10.1 Calculate the percentage molybdenum as follows:MoO3% 5 D 2 E!A/10 w (3)where:D = ceric sulfate solution required to titrate sample, mL,E = ceric sulfate solution r
31、equired to titrate blank, mL,A = mg MoO3/mL of ceric sulfate solution, andw = dried weight of specimen, g.10.2 Calculate the arithmetic mean of each set of observa-tions and report these values to two decimal places.11. Precision and Bias611.1 Eight laboratories participated in supplying data undert
32、he conditions outlined in Practice E 173. Statistical datacalculated in accordance with this practice are recorded in5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical S
33、ociety, 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.6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting
34、 Research Report RR: D32-1020.D3943042Research Report D32-1020, along with standard deviationscalculated by an alternative procedure.11.2 No reference standards were available to determine thebias of the test method.12. Keywords12.1 alumina-base catalysts (fresh); Jones Reduction;molybdenumANNEXES(M
35、andatory Information)A1. ZINC AMALGAM FOR JONES REDUCTORA1.1 PreparationA1.1.1 Place 1000 g of 20mesh zinc (low iron content) ina stout, wide-mouthed glass bottle or jar.A1.1.2 Add 500 mL of a 2 % solution of mercuric chloride,prepared as described in 7.8, to the zinc.A1.1.3 Mix well with a stirring
36、 rod for 45 to 60 s. Ensure allzinc has been fully contacted.A1.1.4 Decant and discard the solution from the zincmixture.A1.1.5 Rinse the zinc amalgam at least 5 times withdeionized water.A1.2 ActivationA1.2.1 Add 500 mL of warm sulfuric acid (1:99), preparedas described in 7.13, to the rinsed amalg
37、am.A1.2.2 Mix well with a stirring rod until all the zinc hasbeen contacted.A1.2.3 Decant and discard the acid solution from the zincmixture.A1.2.4 Rinse the activated zinc amalgam at least 2 to 3times with deionized water.A1.3 StorageA1.3.1 Prepare 1 L of deionized water to which 1 mL ofhydrochlori
38、c acid has been added.A1.3.2 Add sufficient water from A1.3.1 to the activatedzinc amalgam to ensure that all the zinc is covered.A1.3.3 Seal and store until needed.A2. STANDARDIZATION OF CERIC SULFATE SOLUTION USING SODIUM MOLYBDATEA2.1 StandardizationA2.1.1 Clean the Jones reductor thoroughly by p
39、assingrepeatedly through it dilute sulfuric acid (1 + 19) and wateruntil a satisfactory blank is established.A2.1.2 Prepare a ferric ammonium sulfate solution, asdescribed in 7.3 and transfer 25 mL of this solution to thereceiving flask of the Jones reductor. Add 10 mL of concen-trated phosphoric ac
40、id to the receiving flask. Prepare thephosphoric acid-manganous sulfate-sulfuric acid solution asdescribed in 7.4 and transfer 10 mL to the same receiving flaskof the Jones reductor.A2.1.3 Be sure that the tip of the reductor dips well beneaththe surface of the solution. Transfer 100 mL of the molyb
41、de-num standard solution (1 mL = 0.5948 mg MoO3) to a 250-mLbeaker and add 20 mL of (1 + 1)H2SO4.A2.1.4 With gentle suction, draw the molybdenum solutionthrough the reductor, while gently swirling the solution in thereceiving suction flask. Just before the surface of the liquidreaches the zinc, add
42、50 mL of cold H2SO4(1 + 19). Rinse thecolumn twice more by adding 50 mL of water each time. Addthe water just before the surface of the solution reaches thezinc. Close the stopcock while a portion of the last rinsingremains in the reductor funnel. Disconnect and rinse thereductor as a little water i
43、s allowed to run through the stem, andrinse the outside of the stem. Titrate the collected solution withthe ceric sulfate solution as described in 9.4. Correct for areagent blank that has been carried through the entire proce-dure using the same amount of reagents.A2.2 CalculationsA2.2.1 Calculate t
44、he molybdenum oxide equivalent of theceric sulfate solution as follows:A 5 B/C 2 F! (A2.1)where:A = MoO3/mL of ceric sulfate solution,B = molybdenum used expressed as mg MoO3,C = ceric sulfate solution used in titration of the molybde-num, mL, andF = ceric sulfate solution needed to titrate the blan
45、k, mL.D3943043ASTM 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 determination of the validity of any such patent rights, and the riskof infringement of su
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48、e 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 (single 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).D3943044
