1、Designation: D 6159 97 (Reapproved 2007)An American National StandardStandard Test Method forDetermination of Hydrocarbon Impurities in Ethylene by GasChromatography1This standard is issued under the fixed designation D 6159; the number immediately following the designation indicates the year oforig
2、inal 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 methane,ethane, p
3、ropane, propene, acetylene, iso-butane, propadiene,butane, trans-2-butene, butene-1, isobutene, cis-2-butene, me-thyl acetylene and 1,3-butadiene in high-purity ethylene. Thepurity of the ethylene can be calculated by subtracting the totalpercentage of all impurities from 100.00 %. Since this testme
4、thod does not determine all possible 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 permilli
5、on by volume). This test method was 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
6、 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 Stand
7、ards:2D 2504 Test Method for Noncondensable Gases in C2andLighter Hydrocarbon Products by Gas ChromatographyD 2505 Test Method for Ethylene, Other Hydrocarbons, andCarbon Dioxide in High-Purity Ethylene by Gas Chroma-tographyD 5234 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.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 dimeth
9、yl silicone column and a (porous layer 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 todetermin
10、e the ethylene content.4. Significance 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 inte
11、rnal 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.Hydrocarbons higher than n-decane cannot be analyzed by thistest method, if present in the sample. Test Method D 2
12、504addresses the analysis of noncondensable gases and TestMethod D 2505 addresses the analysis of CO2. Guide D 5234describes all potential impurities present in ethylene. Thesestandards should be consulted when determining the totalconcentration of impurities in ethylene.5. Apparatus5.1 Gas Chromato
13、graph (GC), a gas chromatographic in-strument provided with a temperature programmable columnoven and a flame ionization detector (FID). Regulate the carriergas by pressure control.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct
14、 responsibility of SubcommitteeD02.D0.02 on Ethylene.Current edition approved Nov. 1, 2007. Published January 2008. Originallyapproved in 1997. Last previous edition approved in 2002 as D 615997(2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servi
15、ce at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3This column is supplied by major column manufacturers.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unit
16、ed States.Copyright by ASTM Intl (all rights reserved); Thu Sep 11 03:39:14 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.5.2 DetectorUse a flame ionization detector (FID) havinga sensitivity of approximately 2.0 ppmV (1.2 mg/kg) or
17、less forthe compounds listed in 1.1. An FID was exclusively used inthe interlaboratory cooperative study.5.3 Column Temperature ProgrammerThe chromato-graph shall be capable of linear programmed temperatureoperation over a range sufficient for separation of the compo-nents of interest. Section 8 lis
18、ts the recommended operatingconditions. The programming rate shall be sufficiently repro-ducible to obtain retention repeatability of 0.05 min (3 s)throughout the scope of this analysis.5.4 ColumnsCouple the two columns in series with eithera glass press tight connector or a mini-connector equipped
19、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 Al2O3plot columns using sulfates as the deactivatingagent were also used in the interlaboratory comp
20、arison.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 were usedfor the interlaboratory cooperative study.5.5.1 A gas sampling valve placed in an unheated
21、 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 with a variable temperature control.5.6 Gas Sampling Valve and Injection SystemUse a 6-portvalve prov
22、ided 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 problems as deadvolumes, cold spots, long connections, and non-uniform heatedzones. The preferred c
23、arrier 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 50:1 to 100:1 attemperatures of 150C to 200C. Loop sizes of 200500Lwere used in the interlaboratory
24、 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 factors shall not vary morethan 3 %.5.7 Data Acquisition SystemUse any integrator or com-puterized
25、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 of 2 to 204 mg/kg (4 to 340 ppmV)of each of the trace components listed in Table 1 to calibratethe
26、detectors response. The standard gas mixture shall beprepared gravimetrically from known raw materials, and crossFIG. 1 Valve Off Sample LoadingFIG. 2 Valve On InjectionFIG. 3 Valve Off Sample LoadingFIG. 4 Valve On InjectionD 6159 97 (2007)2Copyright by ASTM Intl (all rights reserved); Thu Sep 11 0
27、3:39:14 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.contaminants shall be taken into account. The mixtures shouldbe certified analytically such that the gravimetric and analyti-cally derived values agree to an acceptable tolerance;
28、 that is 61or6 2 %. The concentration of the minor components in thecalibration standard 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
29、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 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
30、 is recom-mended.NOTE 3Compressed 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 response of the FID.NOTE 4Compressed nitrogen is a gas under high pressure.7. Sa
31、mpling7.1 Gas samples are collected in 1000 mL stainless steelcylinders equipped 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
32、excluding airand other contaminants that may be present in the cylinder.8. Preparation 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
33、not be heated above 200Csince above this temperature the column activity is changed.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
34、200CSplit ratio = 50:1 to 100:1Flame Ionization Detector, 300CAir = 300mL/min (see 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 l
35、oop volume = 1060lSample valve temperature = 35 to 45C8.2 When the G.C. has achieved 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 cy
36、linder outletand when the pressure drops to atmospheric pressure and nosample elutes, 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 e
37、ach impu-rity present in the standard, calculate the calibration factor asfollows: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 acquisiti
38、on system.9.2.1 It is important that the system linearity is checked byinjecting 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
39、+ b with b =0.Usea 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.10.2 Connect the gas sample to the G.C. sample port. Flushthe loop for a period of 30 s. Close the sample cylinde
40、r 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 thatTABLE 1 Typical Compounds and Retention Times for CommonHydrocarbon Impurities in EthyleneAComponents Retentio
41、n 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.D 6159 97 (2007)3Copyright by ASTM Intl (
42、all rights reserved); Thu Sep 11 03:39:14 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.obtained with the standard mixture. A typical sample chro-matogram is shown in Fig. 5.11. Calculations11.1 Calculate the concentration of each im
43、purity 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-sition system.11.2 Determine the total
44、 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, CO2,O2,N2,H2O and alcohols, it will be n
45、ecessary to analyze the ethylenefor these impurities as described in Test Methods D 2504 andD 2505. The sum total of all impurities analyzed should beused in reporting the ethylene concentration.12. Precision and Bias412.1 Precision:12.1.1 An interlaboratory cooperative study was adoptedwith 7 labor
46、atories 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 conditions on identical test material
47、swould, 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 between two singleand independent resul
48、ts 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 component.12.2 BiasThere is, at this time, n
49、o accepted referencematerial suitable for measuring bias for this test method.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D021412.FIG. 5 Typical ChromatogramD 6159 97 (2007)4Copyright by ASTM Intl (all rights reserved); Thu Sep 11 03:39:14 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.13. Keywords13.1 ethylene; gas chromatography; hydrocarbon impuritiesASTM International takes no p
