ASTM_D_6212_-_99.pdf

Designation:D 6212 99Standard Test Method forTotal Sulfur in Aromatic Compounds by Hydrogenolysis andRateometric Colorimetry1This standard is issued under the fixed designation D 6212;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of sulfur inaromatic hydrocarbons,their derivatives,and related chemicalshaving typical sulfur concentrations from 0.020 to 10 mg/kg.1.2 This test method may be extended to higher concentra-tions by dilution.1.3 This test method is applicable to aromatic hydrocarbonsand related chemicals such as benzene,toluene,cumene,p-xylene,o-xylene,and to cyclohexane.1.4 The following applies to all specified limits in this testmethod:for purposes of determining conformance with thisstandard,an observed value or a calculated value shall berounded off to the nearest unit in the last right-hand digit usedfor expressing the specification limit in accordance with therounding-off method of Practice E 29.1.5 This standard does not purport to address all the safetyconcerns,if any,associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.Specific precautionary statements aregiven in 6.4,7.5,7.7,and 8.1.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 3437 Practice for Sampling and Handling Liquid CyclicProducts3D 4045 Test Method for Sulfur in Petroleum Products byHydrogenolysis and Rateometric Colorimetry4D 4052 Test Method for Density and Relative Density ofLiquids by Digital Density Meter4D 4790 Terminology of Aromatic Hydrocarbons and Re-lated Chemicals3E 29 Practice for Using Significant Digits in Test Digits inTest Data to Determine Conformance with Specifications52.2Other Documents:OSHA Regulations,29 CFR paragraphs 1910.1 and1910.120063.Terminology3.1 See Terminology D 4790 for definition of terms used inthis test method.4.Summary of Test Method4.1 Reductive ConfigurationThe sample is injected at aconstant rate into a hydrogenolysis apparatus.Within thisapparatus the sample is pyrolyzed at temperatures in the rangeof 1200C to 1300C and in the presence of excess hydrogen.Sulfur compounds are reduced to hydrogen sulfide(H2S).Analysis is by rateometric detection of the colorimetric reac-tion of H2S with lead acetate.Hydrocarbon components areconverted to gaseous such as methane during hydrogenolysis.4.2 OxyhydroPyrolysis ConfigurationSample is injectedat a constant rate into an air stream and introduced into apyrolysis furnace.The sample flows through an inner tubewithin the furnace where it combusts with the oxygen in the aircarrier.SO2and SO3are formed from the sulfur compounds inthe sample.The sample then leaves the inner tube within thepyrolyzer and is mixed with hydrogen within the main reactiontube and is pyrolyzed at temperatures in the range of 1200Cto 1300C(see Fig.1).The SO2and SO3formed within theinner tube are then reduced to H2S.Analysis is by rateometricdetection of the colorimetric reaction of H2S with lead acetate.5.Significance and Use5.1 Sulfur can be a catalyst poison in the aromatic chemicalmanufacturing process.This test method can be used tomonitor the amount of sulfur in aromatic hydrocarbons.Thistest method may also be used as a quality control tool and insetting specifications for sulfur determination in finished prod-ucts.6.Apparatus6.1 The apparatus of this test method can be setup in two1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved Jan.10,1999.Published March 1999.Originallypublished as D 6212 97.Last previous edition D 6212 97.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 06.04.4Annual Book of ASTM Standards,Vol 05.02.5Annual Book of ASTM Standards,Vol 14.02.6Available from Superintendent of Documents,U.S.Government PrintingOffice,Washington,DC 20402.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.FIG.1 Oxyhydrogen Furnace AdapterD 62122different configurations,which will be described herein as the“reductive pyrolysis”configuration,and the“oxyhydropyroly-sis”configuration.The reductive pyrolsis configuration is theone referenced in Test Method D 4045.The oxyhydropyrolysisconfiguration is a modification of the reductive pyrolysisconfiguration that minimizes the formation of coke within thepyrolysis furnace when running aromatic samples.Both setupscan be used to measure sulfur in aromatic compounds asoutlined in this test method.6.2 Pryolysis Furn