ASTM_D_4929_-_15a.pdf

Designation:D492915aStandard Test Methods forDetermination of Organic Chloride Content in Crude Oil1This standard is issued under the fixed designation D4929;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.Scope*1.1 These test methods cover the determination of organicchloride(above 1 g/g organically-bound chlorine)in crudeoils,using either distillation and sodium biphenyl reduction ordistillation and microcoulometry.1.2 These test methods involve the distillation of crude oiltest specimens to obtain a naphtha fraction prior to chloridedetermination.The chloride content of the naphtha fraction ofthe whole crude oil can thereby be obtained.See Section 5regarding potential interferences.1.3 Test Method A covers the determination of organicchloride in the washed naphtha fraction of crude oil by sodiumbiphenyl reduction followed by potentiometric titration.1.4 Test Method B covers the determination of organicchloride in the washed naphtha fraction of crude oil byoxidative combustion followed by microcoulometric titration.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.The preferred concentration units are micrograms ofchloride per gram of sample.1.6 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:2D86 Test Method for Distillation of Petroleum Products andLiquid Fuels at Atmospheric PressureD1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System Performance3.Summary of Test Method3.1 A crude oil distillation is performed to obtain thenaphtha cut at 204 C(400 F).The distillation method wasadapted from Test Method D86 for the distillation of petroleumproducts.The naphtha cut is washed with caustic,repeatedlywhen necessary,until all hydrogen sulfide is removed.Thenaphtha cut,free of hydrogen sulfide,is then washed withwater,repeatedly when necessary,to remove inorganic halides(chlorides).3.2 There are two alternative test methods for determinationof the organic chloride in the washed naphtha fraction,asfollows.3.2.1 Test Method A,Sodium Biphenyl Reduction andPotentiometryThe washed naphtha fraction of a crude oilspecimen is weighed and transferred to a separatory funnelcontaining sodium biphenyl reagent in toluene.The reagent isan addition compound of sodium and biphenyl in ethyleneglycol dimethyl ether.The free radical nature of this reagentpromotes very rapid conversion of the organic halogen toinorganic halide.In effect this reagent solubilizes metallicsodium in organic compounds.The excess reagent isdecomposed,the mixture acidified,and the phases separated.The aqueous phase is evaporated to 25 mL to 30 mL,acetoneis added,and the solution titrated potentiometrically.3.2.2 Test Method B,Combustion and MicrocoulometryThe washed naphtha fraction of a crude oil specimen isinjected into a flowing stream of gas containing about 80%oxygen and 20%inert gas,such as argon,helium,or nitrogen.The gas and sample flow through a combustion tube main-tained at about 800 C.The chlorine is converted to chlorideand oxychlorides,which then flow into a titration cell wherethey react with the silver ions in the titration cell.The silverions thus consumed are coulometrically replaced.The totalcurrent required to replace the silver ions is a measure of thechlorine present in the injected samples.3.2.3 The reaction occurring in the titration cell as chlorideenters is as follows:1These test methods are under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and are the direct responsibilityof Subcommittee D02.03 on Elemental Analysis.Current edition approved Dec.1,2015.Published December 2015.Originallyapproved in 1989.Last previous edition approved in 2015 as D4929 15.DOI:10.1520/D4929-15A.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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Cl21Ag1AgCls!(1)3.2.4 The silver ion consumed in the above reaction isgenerated c