1、Designation: D6159 17Standard Test Method forDetermination of Hydrocarbon Impurities in Ethylene by GasChromatography1This standard is issued under the fixed designation D6159; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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 This test method covers the determination of methane,ethane, propane, propene, acetylene, iso-butane, propadien
3、e,butane, trans-2-butene, butene-1, isobutene, cis-2-butene,methyl acetylene and 1,3-butadiene in high-purity ethylene.The purity of the ethylene can be calculated by subtracting thetotal percentage of all impurities from 100.00 %. Since this testmethod does not determine all possible impurities suc
4、h as CO,CO2,H2O, alcohols, nitrogen oxides, and carbonyl sulfide, aswell as hydrocarbons higher than decane, additional tests maybe necessary to fully characterize the ethylene sample.1.2 Data are reported in this test method as ppmV (parts permillion by gaseous volume) and ppmMol (parts per million
5、Mol). This test method was evaluated in an interlaboratorycooperative study in the concentration range of 4 ppmV to340 ppmV (2 mg kg to 204 mg kg). The participants in theinterlaboratory cooperative study reported the data in non-SIunits. Wherever possible, SI units are included.1.3 This standard do
6、es 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 Sta
7、ndards:2D2504 Test Method for Noncondensable Gases in C2andLighter Hydrocarbon Products by Gas ChromatographyD2505 Test Method for Ethylene, Other Hydrocarbons, andCarbon Dioxide in High-Purity Ethylene by Gas Chroma-tographyD5234 Guide for Analysis of Ethylene Product3. Summary of Test Method3.1 A
8、gaseous ethylene sample is analyzed as received. Thegaseous sample is injected into a capillary gas chromatograph.Sample may be introduced by direct valve injection or by splitvalve injection. The gas chromatograph is provided with a6-port sampling valve and two wide bore capillary columnsconnected
9、in series. These columns are a dimethyl polysilox-ane column and a porous layer open tubular column (PLOT)Al2O3/KCl column. (See Note 1.)Aflame ionization detector isused for detection. The integrated detector signal (peak areas)are corrected for detector response. The hydrocarbon impuri-ties are de
10、termined and the total impurities are used todetermine the ethylene content.NOTE 1This column is supplied by major column manufacturers.4. Significance and Use4.1 High-purity ethylene is required as a feedstock for somemanufacturing processes and the presence of trace amounts ofcertain hydrocarbon i
11、mpurities can have deleterious effects.This test method is suitable for setting specifications, for use asan internal quality control tool, and for use in development orresearch work.4.2 This test method does not detect such impurities as H2O,CO, CO2, and alcohols that may be present in the sample.H
12、ydrocarbons higher than n-decane cannot be analyzed by thistest method, if present in the sample. Test Method D2504addresses the analysis of noncondensable gases and TestMethod D2505 addresses the analysis of CO2. Guide D5234describes all potential impurities present in ethylene. Thesestandards shou
13、ld be consulted when determining the totalconcentration of impurities in ethylene.5. Apparatus5.1 Gas Chromatograph (GC), a gas chromatographic in-strument provided with a temperature programmable columnoven and a flame ionization detector (FID). Carrier gas isregulated by pressure control.5.2 Detec
14、torA flame ionization detector (FID) having asensitivity of approximately 2.0 ppmV (1.2 mg kg) or less forthe compounds listed in 1.1. An FID was exclusively used inthe interlaboratory cooperative study.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fu
15、els, and Lubricants and is the direct responsibility ofSubcommittee D02.D0.02 on Ethylene.Current edition approved Jan. 1, 2017. Published February 2017. Originallyapproved in 1997. Last previous edition approved in 2012 as D6159 97 (2012).DOI: 10.1520/D6159-17.2For referenced ASTM standards, visit
16、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
17、Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Rec
18、ommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.3 Column Temperature ProgrammerThe chromatographshall be capable of linear programmed temperature operationover a range sufficient for separation of the components ofinterest. Section 8 lists the recom
19、mended operating conditions.The programming rate shall be sufficiently reproducible toobtain retention repeatability of 0.05 min (3 s) throughout thescope of this analysis.5.4 ColumnsCouple the two columns in series with eithera glass press tight connector or a mini-connector equipped withgraphite f
20、errules.5.4.1 Column 1, 50 m, 0.53 mm inside diameter (ID) KCldeactivated Al2O3PLOT column. Relative retention is depen-dent on the deactivation method of the column. Other deacti-vated Al2O3plot columns using sulfates as the deactivatingagent were also used in the interlaboratory comparison.5.4.2 C
21、olumn 2, 30 m, 0.53 mm ID, 5 m film thicknessmethyl polysiloxane. This column improves the separation ofmethyl acetylene, iso-pentane, and n-pentane.5.5 Sample Inlet SystemTwo injection modes were usedfor the interlaboratory cooperative study.5.5.1 A gas sampling valve placed in an unheated zone oft
22、he gas chromatograph injecting the sample directly into thecolumn.5.5.2 A gas sampling valve placed in an unheated zone ofthe gas chromatograph in conjunction with a splitter injectorheated with a variable temperature control.5.5.3 A gas sampling valve maintained at a constant tem-perature above amb
23、ient temperature may also be used, forexample, by installation in a valve oven or equivalent.5.6 Gas Sampling Valve and Injection System:5.6.1 Direct Valve InjectionUse a 6-port valve providedwith116 in. fittings as the sample injection system. A typicalvalve arrangement is shown in Fig. 1 and Fig.
24、2.A10Lto60 L loop as shown in Fig. 1 has proven satisfactory to attainthe detection limits described in this test method and notoverload the column. Use good valve piping techniques tominimize dead volumes, cold spots, and long connections; aswell as to ensure uniform heated zones. The preferred car
25、riergas control for sample introduction is pressure regulation. It isrecommended that linearity for the impurity components beverified either from multiple standards or careful dilution of thesingle calibration standard.5.6.2 Split Valve InjectionUse a 6-port valve in conjunc-tion with a splitter in
26、jector. A typical arrangement is shown inFig. 3 and Fig. 4. Split ratios of 50:1 to 100:1 at split injectortemperatures of 150 C to 200 C yield acceptable results.Loop sizes of 200 L to 500 L were used in the interlabora-tory study. When using a splitter it is important to checklinearity of the spli
27、tter. Inject the standard blend at 50:1, 75:1,and 100:1 split ratios. Check the response factors of the listedimpurities as determined in 9.1, and the factors shall not varymore than 3 %. Linearity may be verified when the system isplaced into service and when major maintenance is performed,such as
28、installation of new GC columns.5.7 Data Acquisition SystemUse a computerized dataacquisition system for peak area integration, as well as forrecording the chromatographic trace.6. Reagent Materials6.1 Standard MixtureUse a gravimetrically blended gasstandard containing levels of 2 mg kg to 204 mg kg
29、 (4 ppmVto 340 ppmV as a gas) of each of the trace components listedin Table 1 to calibrate the detectors response. The standard gasmixture shall be prepared gravimetrically from known rawmaterials, and cross contaminants shall be taken into account.The mixtures should be certified analytically such
30、 that thegravimetric and analytically derived values agree to an accept-able tolerance; that is 6 1%or6 2 %. The concentration ofthe minor components in the calibration standard shall bewithin 20 % to 50 % above the concentration of the processstream or samples. Convert the gravimetric concentration
31、s toppmMol and its equivalent gaseous volumes ppmV as follows:Moli5 giMWi(1)where:Moli= the absolute mole from gravimetric standard ofcompound i including ethylene,gi= is the mass in grams of compound i from thegravimetric standard, andMWi= is the molecular weight of compound i.and the ppmMol and pp
32、mV can then be calculated asfollows:FIG. 1 Direct Valve Injection Sample Introduction: Valve OffSample LoadingFIG. 2 Direct Valve Injection Sample Introduction: Valve OnInjectionD6159 172ppmMoli5 ppmVi5 10E6 3 Moli#Moliton# (2)where:ppmMoli= final ppmMol of component i in the calibrationstandard,ppm
33、Vi= final ppmV of component i in the calibrationstandard, andMoliton= sum of moles of all components i from i to nin the calibration standard and where n is thenumber of distinct components, inclusive ofethylene.Table 2 gives an example calculation.6.2 Compressed Helium, gas having purity of 99.999
34、%, orbetter, with a total hydrocarbon level of 1 ppmV.NOTE 2Compressed helium is a gas under high pressure.6.3 Compressed Hydrogen, gas used as fuel in the FIDdetector (less than 1.0 ppmV hydrocarbon impurities).NOTE 3Hydrogen is an extremely flammable gas under high pressure.6.4 Compressed AirAir h
35、aving less than 1.0 ppmV ofhydrocarbon impurities for the operation of the FID is recom-mended.NOTE 4Compressed air is a gas under high pressure and supportscombustion.6.5 Compressed NitrogenNitrogen having less than 1.0ppmV of hydrocarbon impurities is used as make up gas inorder to increase the re
36、sponse of the FID.NOTE 5Compressed nitrogen is a gas under high pressure.7. Sampling7.1 Gas samples are collected in 1000 mL stainless steelcylinders equipped with a rupture disk capable of sustaining5500 kPa to 6900 kPa (800 psi to 1000 psi) in order to protectagainst dangerous pressure build up. I
37、t is important to thor-oughly flush the cylinder with the sample prior to sealing, thusexcluding air and other contaminants that may be present in thecylinder. Ensure that sampling does not concentrate preferen-tially the higher boiling hydrocarbons during the purging step.8. Preparation of Apparatu
38、s8.1 Instrument ConditionsAdjust the instrumental param-eters to the following conditions:Column TemperatureEquilibration time: 2.0 minInitial: 35 CFinal: 190 C (see Note 6)NOTE 6PLOT Al2O3columns should not be heated above 200 Csince above this temperature the column activity is changed.Rate: 4 C m
39、inInitial time: 2.0 minFinal time: 15 min.Carrier GasHelium at 6 mL min to 8 mL/minInjection System with SplitterSample valve loop volume = 200 L to 500 LSample valve temperature = 35 C to 45 CSplitter temperature = 150 C to 200 CSplit ratio = 50:1 to 100:1Flame Ionization Detector, 300 CAir = 300mL
40、/min (see Note 7)FIG. 3 Split Valve Injection Sample Introduction: Valve OffSample LoadingFIG. 4 Split Valve Injection Sample Introduction: Valve OnInjectionTABLE 1 Typical Compounds and Retention Times for CommonHydrocarbon Impurities in EthyleneAComponents Retention Time, minMethane 7.02Ethane 8.1
41、2Ethene 9.00Propane 12.41Propene 16.93Ethyne 19.52Isobutane 19.76Propadiene 20.48Butane 20.78t-2-Butene 24.99Butene-1 25.23Isobutylene 25.90c-2-Butene 26.71Propyne 29.141,3-Butadiene 30.37AConditions as specified in Section 8.D6159 173NOTE 7Follow the values suggested by instrument manufacturer.H2=
42、30 mL minMakeup = N2at 20 mL minRange = suitable to obtain measurable counts for theimpuritiesInjection System using a Valve DirectlySample valve loop volume = 10 L to 60 LSample valve temperature = 35 C to 45 C8.2 When the G.C. has achieved a ready status, proceed withanalysis.9. Calibration9.1 Aft
43、er demonstrating linearity of the calibration compo-nents in 5.6.2, proceed to inject the standard mixture. Connectthe gaseous sample to the sample port and flush the sampleloop for a period of 30 s. Close the standard sample cylinderoutlet and when the pressure drops to atmospheric pressure andno s
44、ample elutes when using a bubbler at valve exit line.Alternatively, a pressure electronic monometer that can sensi-tively measure the range around atmospheric pressure may beused, inject the standard sample and proceed with the analysis.At least three standard determinations should be made to obtain
45、a relative standard deviation of the measurements.9.2 Determination of Calibration FactorsFor each impu-rity present in the standard, calculate the calibration factor asfollows:Cf 5 Ci/Ai (3)where:Cf = the calibration factor,Ci = the concentration of the impurity i in the standard(usually expressed
46、as ppmV or ppmMol), andAi = the area counts obtained for that impurity as integratedby the data acquisition system.9.2.1 It is important that the system linearity is checked(5.6) by injecting standard gas samples of varying impurityconcentration over a range covering the impurity concentrationrange
47、in the samples analyzed. Verify that the system respondslinearly and that the response is of the type y = mx + b with b= 0. Use a linear calibration forced through the origin.10. Procedure10.1 The sample shall be injected under the same tempera-ture and pressure conditions as the standard mixture.10
48、.2 Connect the gas sample to the GC sample port. Flushthe loop for a period of 30 s. Close the sample cylinder shut-offvalve and inject the sample the moment the loop reachesatmospheric pressure. Integrate the areas of the impurities.Identify the impurities by comparing their retention time to thato
49、btained with the standard mixture. A typical sample chro-matogram is shown in Fig. 5.11. Calculations11.1 Calculate the concentration of each impurity com-pound to the nearest ppmV and ppmMol as follows:Ci 5 Cfi!Ai! (4)whereCi = concentration of the impurity in the sample in ppmVor ppmMol,Cfi = calibration factor previously calculated in Eq 3 (unitsare usually ppmV/counts or ppmMol/area), andAi = integrated area of the impurity from the data acquisi-tion system.11.2 Determine the total amount of hydroca
