1、Designation: D 6159 97 (Reapproved 2002)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 is used for the determination ofmethane, etha
3、ne, propane, propene, acetylene, iso-butane,propadiene, butane, trans-2-butene, butene-1, isobutene, cis-2-butene, methyl acetylene and 1,3-butadiene in high-purityethylene. The purity of the ethylene can be calculated bysubtracting the total percentage of all impurities from 100.00%. Since this tes
4、t method does not determine all possibleimpurities such as CO, CO2,H2O, alcohols, nitrogen oxides,and carbonyl sulfide, as well as hydrocarbons higher thandecane, additional tests may be necessary to fully characterizethe ethylene sample.1.2 Data are reported in this test method as ppmV (parts permi
5、llion 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 d
6、ose 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 St
7、andards:D 2504 Test Method for Noncondensable Gases in C2andLighter Hydrocarbon Products by Gas Chromatography2D 2505 Test Method for Ethylene, Other Hydrocarbons, andCarbon Dioxide in High-Purity Ethylene by Gas Chroma-tography2D 5234 Guide for Analysis of Ethylene Product33. Summary of Test Method
8、3.1 A 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 d
9、imethyl silicone column and a (porous layer open tubularcolumn (PLOT) Al2O3/KCl column.4A 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 todet
10、ermine 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
11、 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.Hydrocarbons higher than n-decane cannot be analyzed by thistest method, if present in the sample. Test Metho
12、d D 2504addresses 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 Chr
13、omatograph (GC), a gas chromatographic in-strument 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 les
14、s 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 lists
15、the recommended operating1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.D0 on Hydrocarbons for Chemical and Special Uses.Current edition approved Dec. 10, 2002. Published March 2003. Originally
16、approved in 1997. Last previous edition approved in 1997 as D 6159 97.2Annual Book of ASTM Standards, Vol 05.01.3Annual Book of ASTM Standards, Vol 05.02.4This column is supplied by major column manufacturers.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
17、428-2959, United States.conditions. 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 with
18、graphite ferrules.5.4.1 Column 1, 50 m, 0.53 mm inside diameter (ID) KCldeactivated Al2O3PLOT column.4Relative 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 comparis
19、on.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 zon
20、e 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 provided
21、 with116 in. fittings as the sample injectionsystem. A typical 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 car
22、rier 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 s
23、tudy. 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 da
24、ta 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 de
25、tectors response. The standard gas mixture shall beprepared gravimetrically from known raw materials, and crosscontaminants shall be taken into account. The mixtures shouldbe certified analytically such that the gravimetric and analyti-cally derived values agree to an acceptable tolerance; that is 6
26、1or6 2 %. The concentration of the minor components in thecalibration standard shall be within 20 to 50 % above theconcentration of the process stream or samples.FIG. 1 Valve Off Sample LoadingFIG. 2 Valve On InjectionFIG. 3 Valve Off Sample LoadingFIG. 4 Valve On InjectionD 6159 97 (2002)26.2 Compr
27、essed 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 FIDdetector (less than 1.0 ppmV hydrocarbon impurities).NOTE 2Hydrogen is an extremely flammable gas un
28、der 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 supportscombustion.6.5 Compressed NitrogenNitrogen having less than 1.0ppmV of hydrocarbon impurities is used
29、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 with a rupture disk capable of sustaining5500 to 6900 kPa (800 to 1000 psi) in order to protect agai
30、nstdangerous 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. Preparation of Apparatus8.1 Instrument ConditionsAdjust the instrumental param-eters to the following cond
31、itions:Column TemperatureEquilibration time: 2.0 minInitial: 35CFinal: 190C5Rate: 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 200CSpli
32、t ratio = 50:1 to 100:1Flame Ionization Detector, 300CAir = 300mL/min6H2= 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
33、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
34、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 asfollow
35、s: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
36、 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.
37、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 cylinder shut-offvalve and inject the sample the moment the loop reachesatmospheric pre
38、ssure. 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. 5.11. Calculations11.1 Calculate the concentration of each impurity to thenearest ppmV as follows:5PLOT Al
39、2O3columns should not be heated above 200C since above thistemperature the column activity is changed.6Follow the values suggested by instrument manufacturer.TABLE 1 Typical Compounds and Retention Times for CommonHydrocarbon Impurities in EthyleneAComponents Retention Time, minMethane 7.02Ethane 8.
40、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 (2002)3Ci 5 Cfi!Ai! (2)whereCi = concentration of the impurity
41、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 amount of hydrocarbon impuritiesby summing the concentrations of the individual impurities.C
42、alculate 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 necessary to analyze the ethylenefor these impurities as described in Test Methods D 2504 andD
43、 2505. The sum total of all impurities analyzed should beused in reporting the ethylene concentration.12. Precision and Bias712.1 Precision:12.1.1 An interlaboratory cooperative study was adoptedwith 7 laboratories participating. Fourteen hydrocarbon impu-rities in ethylene were measured; the result
44、s 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 materialswould, in the long run, and in the normal and correct operationof the test method exceed the
45、 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 results obtained by different operators work-ing in different laboratories on identical material w
46、ould, 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, no accepted referencematerial suitable for measuring bias for this test method.13. Keywords13.
47、1 ethylene; gas chromatography; hydrocarbon impurities7Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D021412.FIG. 5 Typical ChromatogramD 6159 97 (2002)4ASTM International takes no position respecting the validity of any paten
48、t 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 rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision a
49、t 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 attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on St
