1、Designation: D6159 97 (Reapproved 2012)Standard 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 o
2、f 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 methane,ethane, propane, propene, acetylene, iso-
3、butane, propadiene,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 possib
4、le impurities such 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 volume). This test method wa
5、s evaluated in aninterlaboratory cooperative study in the concentration range of4 to 340 ppmV (2 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 dose not purport to address all of the
6、safety 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:2D2504 Test Method for Noncon
7、densable 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 gaseous ethylene sample is analyzed
8、as received. Thegaseous sample is injected into a capillary gas chromatograph.A split-injector may or may not be used. The gas chromato-graph is provided with a 6port sampling valve and two widebore capillary columns connected in series. These columns area dimethyl silicone column and a (porous laye
9、r open tubularcolumn (PLOT) Al2O3/KCl column.3A flame ionization detec-tor is used for detection. The integrated detector signal (peakareas) are corrected for detector response. The hydrocarbonimpurities are determined and the total impurities are used todetermine the ethylene content.4. Significanc
10、e and Use4.1 High-purity ethylene is required as a feedstock for somemanufacturing processes and the presence of trace amounts ofcertain hydrocarbon impurities can have deleterious effects.This test method is suitable for setting specifications, for use asan internal quality control tool, and for us
11、e 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.Hydrocarbons higher than n-decane cannot be analyzed by thistest method, if present in the sample. Test Method D2504addresses the analysis of nonconden
12、sable gases and TestMethod D2505 addresses the analysis of CO2. Guide D5234describes all potential impurities present in ethylene. Thesestandards should be consulted when determining the totalconcentration of impurities in ethylene.5. Apparatus5.1 Gas Chromatograph (GC), a gas chromatographic in-str
13、ument provided with a temperature programmable columnoven and a flame ionization detector (FID). Regulate the carriergas by pressure control.5.2 DetectorUse a flame ionization detector (FID) havinga sensitivity of approximately 2.0 ppmV (1.2 mg/kg) or less forthe compounds listed in 1.1. An FID was
14、exclusively used inthe interlaboratory cooperative study.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.D0.02 on Ethylene.Current edition approved Dec. 1, 2012. Published December 2012. Origina
15、llyapproved in 1997. Last previous edition approved in 2007 as D615997(2007).DOI: 10.1520/D6159-97R12.2For 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
16、Document Summary page onthe ASTM website.3This column is supplied by major column manufacturers.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.3 Column Temperature ProgrammerThe chromatographshall be capable of linear programmed te
17、mperature operationover a range sufficient for separation of the components ofinterest. Section 8 lists the recommended 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 ColumnsCoup
18、le the two columns in series with eithera glass press tight connector or a mini-connector equipped withgraphite ferrules.5.4.1 Column 1, 50 m, 0.53 mm inside diameter (ID) KCldeactivated Al2O3PLOT column.3Relative retention is depen-dent on the deactivation method of the column. Other deacti-vated A
19、l2O3plot columns using sulfates as the deactivatingagent were also used in the interlaboratory comparison.5.4.2 Column 2, 30 m, 0.53 mm ID, 5m film thicknessmethyl silicone. This column improves the separation ofmethyl acetylene, iso-pentane, and n-pentane.5.5 Sample Inlet SystemTwo injection modes
20、were usedfor the interlaboratory cooperative study.5.5.1 A gas sampling valve placed in an unheated zone ofthe 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 wi
21、th a variable temperature control.5.6 Gas Sampling Valve and Injection SystemUse a 6-portvalve provided with116 in. fittings as the sample injectionsystem.Atypical valve arrangement is shown in Fig. 1 and Fig.2. Use a 1060L loop as shown in Fig. 1. Use good valvemaintenance techniques to avoid such
22、problems as deadvolumes, cold spots, long connections, and non-uniform heatedzones. The preferred carrier gas arrangement for sampleintroduction is pressure regulation. Use a 6-port valve inconjunction with a splitter injector. A typical arrangement isshown in Fig. 3 and Fig. 4. Use split ratios of
23、50:1 to 100:1 attemperatures of 150C to 200C. Loop sizes of 200500Lwere used in the interlaboratory study. When using a splitter itis important to check linearity of the splitter. Inject the standardblend at 50:1, 75:1, and 100:1 split ratios. Check the responsefactors as determined in 9.1, and the
24、factors shall not vary morethan 3 %.5.7 Data Acquisition SystemUse any integrator or com-puterized data acquisition system for peak area integration, aswell as for recording the chromatographic trace.6. Reagent Materials6.1 Standard MixtureUse a gravimetrically blended gasstandard containing levels
25、of 2 to 204 mg/kg (4 to 340 ppmV)of each of the trace components listed in Table 1 to calibratethe detectors response. The standard gas mixture shall beprepared gravimetrically from known raw materials, and crosscontaminants shall be taken into account. The mixtures shouldbe certified analytically s
26、uch that the gravimetric and analyti-cally derived values agree to an acceptable tolerance; that is 6FIG. 1 Valve Off Sample LoadingFIG. 2 Valve On InjectionFIG. 3 Valve Off Sample LoadingFIG. 4 Valve On InjectionD6159 97 (2012)21or6 2 %. The concentration of the minor components in thecalibration s
27、tandard shall be within 20 to 50 % above theconcentration of the process stream or samples.6.2 Compressed Helium, gas having purity of 99.999 %, orbetter, with a total hydrocarbon level of 1ppmV.NOTE 1Compressed helium is a gas under high pressure.6.3 Compressed Hydrogen, gas used as fuel in the FID
28、detector (less than 1.0 ppmV hydrocarbon impurities).NOTE 2Hydrogen is an extremely flammable gas under high pressure.6.4 Compressed AirAir having less than 1.0 ppmV ofhydrocarbon impurities for the operation of the FID is recom-mended.NOTE 3Compressed air is a gas under high pressure and supportsco
29、mbustion.6.5 Compressed NitrogenNitrogen having less than 1.0ppmV of hydrocarbon impurities is used as make up gas inorder to increase the response of the FID.NOTE 4Compressed nitrogen is a gas under high pressure.7. Sampling7.1 Gas samples are collected in 1000 mL stainless steelcylinders equipped
30、with a rupture disk capable of sustaining5500 to 6900 kPa (800 to 1000 psi) in order to protect againstdangerous pressure build up. It is important to thoroughly flushthe cylinder with the sample prior to sealing, thus excluding airand other contaminants that may be present in the cylinder.8. Prepar
31、ation of Apparatus8.1 Instrument ConditionsAdjust the instrumental param-eters to the following conditions:Column TemperatureEquilibration time: 2.0 minInitial: 35CFinal: 190C (see Note 5)NOTE 5PLOT Al2O3columns should not be heated above 200Csince above this temperature the column activity is chang
32、ed.Rate: 4C/minInitial time: 2.0 minFinal time: 15 min.Carrier GasHelium at 6 to 8 mL/minInjection System with SplitterSample valve loop volume = 200500lSample valve temperature = 35 to 45CSplitter temperature = 150 to 200CSplit ratio = 50:1 to 100:1Flame Ionization Detector, 300CAir = 300mL/min (se
33、e Note 6)NOTE 6Follow the values suggested by instrument manufacturer.H2= 30mL/minMakeup = N2at 20mL/minRange = suitable to obtain measurable counts for theimpuritiesInjection System using a Valve DirectlySample valve loop volume = 1060lSample valve temperature = 35 to 45C8.2 When the G.C. has achie
34、ved a ready status, proceed withanalysis.9. Calibration9.1 Proceed to inject the standard mixture. Connect thegaseous sample to the sample port and flush the sample loopfor a period of 30 s. Close the standard sample cylinder outletand when the pressure drops to atmospheric pressure and nosample elu
35、tes, inject the standard sample and proceed with theanalysis.At least three standard determinations should be madeto obtain 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
36、:Cf 5 Ci/Ai (1)where:Cf = the calibration factor,Ci = the concentration of the impurity i in the standard(usually expressed as ppmV), 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 byinjecting
37、standard gas samples of varying impurity concentra-tion over a range covering the impurity concentration range inthe samples analyzed. Verify that the system responds linearlyand that the response is of the type y = mx + b with b =0.Usea linear calibration forced through the origin.10. Procedure10.1
38、 The sample shall be injected under the same tempera-ture and pressure conditions as the standard mixture.10.2 Connect the gas sample to the G.C. 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 pres
39、sure. Integrate the areas of the impurities.Identify the impurities by comparing their retention time to thatobtained with the standard mixture. A typical sample chro-matogram is shown in Fig. 5.TABLE 1 Typical Compounds and Retention Times for CommonHydrocarbon Impurities in EthyleneAComponents Ret
40、ention Time, minMethane 7.02Ethane 8.12Ethene 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 97 (2012)311. Calculations11.1
41、 Calculate the concentration of each impurity to thenearest ppmV as follows:Ci 5 Cfi!Ai! (2)whereCi = concentration of the impurity in the sample in ppmV,Cfi = calibration factor previously calculated in Eq 1 (unitsare usually ppmV/counts), andAi = integrated area of the impurity from the data acqui
42、si-tion system.11.2 Determine the total amount of hydrocarbon impuritiesby summing the concentrations of the individual impurities.Calculate the concentration of the ethylene by subtracting thetotal impurities concentration from 100.00 %. Since this testmethod cannot measure such impurities as CO, C
43、O2,O2,N2,H2O and alcohols, it will be necessary to analyze the ethylenefor these impurities as described in Test Methods D2504 andD2505. The sum total of all impurities analyzed should be usedin reporting the ethylene concentration.12. Precision and Bias412.1 Precision:12.1.1 An interlaboratory coop
44、erative study was adoptedwith 7 laboratories participating. Fourteen hydrocarbon impu-rities in ethylene were measured; the results obtained areshown in Table 2.12.1.2 RepeatabilityThe difference between successiveresults obtained by the same operator with the same apparatusunder constant operating
45、conditions on identical test materialswould, in the long run, and in the normal and correct operationof the test method exceed the values only one case in twenty asshown in Table 2, where r is the repeatability and X is theconcentration (ppmV) of the component.12.1.3 ReproducibilityThe difference be
46、tween two singleand independent results obtained by different operators work-ing in different laboratories on identical material would, in thelong run, exceed the values in only one case in twenty asshown in Table 2, where R is the reproducibility and X is themean concentration (ppmV) of the compone
47、nt.12.2 BiasThere is, at this time, no accepted referencematerial suitable for measuring bias for this test method.13. Keywords13.1 ethylene; gas chromatography; hydrocarbon impurities4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report
48、 RR:D02-1412.FIG. 5 Typical ChromatogramD6159 97 (2012)4ASTM 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
49、 rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may
