1、Designation: D2505 88 (Reapproved 2010)Standard Test Method forEthylene, Other Hydrocarbons, and Carbon Dioxide in High-Purity Ethylene by Gas Chromatography1This standard is issued under the fixed designation D2505; the number immediately following the designation indicates the year oforiginal adop
2、tion 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. Scope1.1 This test method covers the determination of carbondioxide, methane, eth
3、ane, acetylene, and other hydrocarbons inhigh-purity ethylene. Hydrogen, nitrogen, oxygen, and carbonmonoxide are determined in accordance with Test MethodD2504. The percent ethylene is obtained by subtracting thesum of the percentages of the hydrocarbon and nonhydrocar-bon impurities from 100. The
4、method is applicable over therange of impurities from 1 to 500 parts per million volume(ppmV).1.2 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 pra
5、ctices and determine the applica-bility of regulatory limitations prior to use. For some specifichazard statements, see Section 6.1.3 The values stated in acceptable metric units are to beregarded as the standard. The values in parentheses are forinformation only.2. Referenced Documents2.1 ASTM Stan
6、dards:2D2504 Test Method for Noncondensable Gases in C2andLighter Hydrocarbon Products by Gas ChromatographyD4051 Practice for Preparation of Low-Pressure GasBlendsE260 Practice for Packed Column Gas ChromatographyF307 Practice for Sampling Pressurized Gas for Gas Analy-sis3. Summary of Test Method3
7、.1 The sample is separated in a gas chromatograph systemutilizing four different packed chromatographic columns withhelium as the carrier gas. Methane and ethane are determinedby using a silica gel column. Propylene and heavier hydrocar-bons are determined using a hexamethylphosphoramide(HMPA) colum
8、n. Acetylene is determined by using, in series,a hexadecane column and a squalane column. Carbon dioxideis determined using a column packed with activated charcoalimpregnated with a solution of silver nitrate in b,b8-oxydipropionitrile. Columns other than those mentioned abovemay be satisfactory (se
9、e 5.3). Calibration data are obtainedusing standard samples containing the impurities, carbondioxide, methane, and ethane in the range expected to beencountered. Calibration data for acetylene are obtained as-suming that acetylene has the same peak area response on aweight basis as methane. The acet
10、ylene content in a sample iscalculated on the basis of the ratio of peak area of the acetylenepeak to the peak area of a known amount of methane.Calculations for carbon dioxide, methane, and ethane arecarried out by the peak-height measurement method.4. Significance and Use4.1 High-purity ethylene i
11、s required as a feedstock for somemanufacturing processes, and the presence of trace amounts ofcarbon dioxide and some hydrocarbons can have deleteriouseffects. This method is suitable for setting specifications, foruse as an internal quality control tool and for use in develop-ment or research work
12、.5. Apparatus5.1 Any chromatographic instrument with an overall sensi-tivity sufficient to detect 2 ppmV or less of the compoundslisted with a peak height of at least 2 mm without loss ofresolution.5.2 DetectorsThermal ConductivityIf a methanation re-actor is used, a flame ionization detector is als
13、o required. Todetermine carbon dioxide with a flame ionization detector, amethanation reactor must be inserted between the column and1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.D0.02 on Ethy
14、lene.Current edition approved May 1, 2010. Published May 2010. Originallyapproved in 1966. Last previous edition approved in 2004 as D2505 88 (2004)E1.DOI: 10.1520/D2505-88R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo
15、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the detector and hydrogen added as a reduction gas (see TestMethod D25
16、04, Appendix X1, Preparation of MethanationReactor).5.3 ColumnAny column or set of columns can be usedthat separates carbon dioxide, methane, acetylene and C3andheavier compounds. There may be tailing of the ethylene peakbut do not use any condition such that the depth of the valleysahead of the tra
17、ce peak is less than 50 % of the trace peakheight. (See Fig. 1 for example.)5.4 RecorderA recorder with a full-scale response of 2 sor less and a maximum rate of noise of 60.3 % of full scale.5.5 Gas-Blending ApparatusA typical gas-blending appa-ratus is shown in Fig. 2. A high-pressure manifold equ
18、ippedwith a gage capable of accurately measuring ethylene pressuresup to 3.4 MN/m2gage (500 psig) is required. Other types ofgas-blending equipment, such as described in Practice D4051,can be used.NOTE 1 Practice E260 contains information that will be helpful tothose using this method.6. Reagents an
19、d Materials6.1 Copper or Aluminum, or Stainless Steel Tubing, 6.4-mm(14-in. ) outside diameter, and nylon tubing, 3.2-mm (18-in.)outside diameter.6.2 Solid SupportsCrushed firebrick or calcined diatoma-ceous earth, such as Chromosorb P,335 to 80-mesh and 80 to100-mesh. Other supporting materials or
20、mesh sieves can besatisfactory.6.3 Active SolidsActivated carbon, 30 to 40-mesh,4silicagel, 100 to 200-mesh.5Other sizes may be satisfactory.6.4 Liquid PhasesHexamethylphosphoramide (HMPA6),hexadecane.6Squalene,6silver nitrate, and b,b8-oxydipropionitrile.7Other liquid phases may be satisfactory.(Wa
21、rningCombustible solvents. See A1.7.) (WarningHMPAmay be harmful if inhaled. Causes irritation.Apotentialcarcinogen (lungs). See A1.5.)6.5 Helium.(WarningCompressed Gas, Hazardous Pres-sure. See A1.2.)6.6 Hydrogen.(WarningFlammable Gas, HazardousPressure. See A1.6.)6.7 Acetone.(WarningExtremely Flam
22、mable. See A1.1.)6.8 Gases for CalibrationPure or research grade carbondioxide, methane, ethane, acetylene, ethylene, propane, andpropylene. Certified calibration blends are commercially avail-able from numerous sources and may be used. (WarningFlammable Gases, Hazardous Pressure. See A1.2 and A1.3.
23、)6.9 Methanol.(WarningFlammable. Vapor Harmful. SeeA1.4.)3The sole source of supply of the apparatus is available from the Celite Division,Johns Mansville Co., New York, NY. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your com-ments w
24、ill receive careful consideration at a meeting of the responsible technicalcommittee1, which you may attend.4A fraction sieved in the laboratory to 30 to 40 mesh from medium activitycharcoal, 20 to 60 mesh, sold by Central Scientific Co., 1700 Irving Park Road,Chicago, IL 60613, has been found satis
25、factory for this purpose. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee1, which you may attend.5The sole source of supply of the apparatu
26、s known to the committee at this timeis Silica gel Code 923 available from the Davison Chemical Co., Baltimore, Md.21203. If you are aware of alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of th
27、e responsible technical committee1, which you may attend.6The sole source of supply of the apparatus known to the committee at this timeis available from the Fisher Scientific Co., St. Louis, MO. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquart
28、ers. Your comments will receive careful consideration at a meeting of theresponsible technical committee1, which you may attend.7b,b8-oxydipropionitrile, sold by Distillation Products Industries, Division ofEastman Kodak Co., Rochester, NY, has been found to be satisfactory. If you areaware of alter
29、native suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will receive careful consideration at a meetingof the responsible technical committee1, which you may attend.FIG. 1 Typical Chromatogram for PropyleneFIG. 2 Gas-Blending ManifoldD2505 88 (2010)2NOTE
30、2The use of copper tubing is not recommended with samplescontaining acetylene as this could lead to the formation of potentiallyexplosive copper acetylide.7. Sampling7.1 Samples should be supplied to the laboratory in highpressure sample cylinders, obtained using the proceduresdescribed in Practice
31、F307, or similar methods.8. Preparation of Apparatus8.1 Silica Gel ColumnDry the silica gel in an oven at204C (400F) for 3 h, cool in a desiccator, and store inscrew-cap bottles. Pour the activated silica gel into a 0.9-m(3-ft) length of 6.4-mm (14-in.) outside diameter copper oraluminum tubing plug
32、ged with glass wool at one end. Tap orvibrate the tube while adding the silica gel to ensure uniformpacking and plug the top end with glass wool. Shape thecolumn to fit into the chromatograph.8.2 Silver Nitrateb,b8-OxydipropionitrileActivatedCarbon ColumnWeigh 10 g of b,b8-oxydipropionitrile into ab
33、rown 125-mL (4-oz) bottle. Add5gofsilver nitrate (AgNO3)crystals. With occasional shaking, dissolve as much AgNO3aspossible, and allow the bottle to stand overnight to ensuresaturation. Prepare this solution fresh, as required. Withoutdisturbing the crystals at the bottom of the bottle, weigh 2.5 go
34、f supernatant AgNO3solution into a 250-mL beaker and add50 mL of methanol. While stirring this mixture, slowly add22.5 g of activated carbon. Place the beaker on a steam bath toevaporate the methanol. When the impregnated activatedcarbon appears to be dry, remove the beaker from the steambath and fi
35、nish drying in an oven at 100 to 110C for 2 h. Plugone end of a 4-ft (1.2-m) length of 6.4-mm (14-in.) outsidediameter aluminum or stainless steel tubing with glass wool.Hold the tubing vertically with the plugged end down and pourfreshly dried column packing into it, vibrating the columnduring fill
36、ing to ensure uniform packing. Plug the top end withglass wool and shape the tubing so that it may be mountedconveniently in the chromatograph.8.3 Hexamethylphosphoramide Column (HMPA)Dry the35 to 80-mesh inert support at 204C (400F). Weigh 75 g intoa wide-mouth 500-mL (16-oz) bottle.Add 15 g of HMP
37、Ato theinert support and shake and roll the mixture until the supportappears to be uniformly wet with the HMPA. Pour the packinginto a 6-m (20-ft) length of 6.4-mm (14-in.) outside diametercopper of aluminum tubing plugged at one end with glasswool. Vibrate the tubing while filling to ensure more un
38、iformpacking. Plug the top end of the column with glass wool andshape the column to fit into the chromatograph.8.4 Hexadecane-Squalane ColumnDissolve 30 g of hexa-decane into approximately 100 mL of acetone. Add 70 g of 80to 100-mesh inert support. Mix thoroughly and pour themixture into an open pan
39、 for drying. The slurry should bestirred during drying to ensure uniform distribution. When theacetone has evaporated, add a portion of the packing to a 7-m(25-ft) length of 3.2-mm (18-in.) outside diameter nylon tubingwhich has been plugged at one end with glass wool. Vibrate thecolumn while fillin
40、g to ensure more uniform packing. Fill thecolumn with packing to only 4 m (15 ft) of the length of thecolumn. Fill the remainder of the column with squalanepacking prepared in the same manner as the hexadecanepacking. Plug the open end of the tubing with glass wool andshape the column to fit into th
41、e chromatograph with thehexadecane portion of the column at the front end of thecolumn. The column shall be purged under test conditions (nosample added) until a constant baseline is obtained.NOTE 3Columns made with liquid phases listed above were usedsatisfactorily in cooperative work. Other column
42、s may be used (see 5.3).9. Calibration9.1 Preparation of Standard Mixtures:9.1.1 Preparation of ConcentratePrepare a concentrate ofthe impurities expected to be encountered. A certified calibra-tion blend containing the expected impurities can be obtainedand used as the concentrate. An example of a
43、satisfactoryconcentrate is given in Table 1. The concentrate can beprepared using the gas blending manifold as shown in Fig. 2 orusing a similar apparatus as follows: Evacuate the apparatusand add the components in the order of increasing vaporpressure; that is, propylene, carbon dioxide, ethane and
44、 meth-ane. Record the increase in pressure on the manometer as eachcomponent is added. Close the reservoir and evacuate themanometer after each addition.9.1.2 Dilution of ConcentrateDilute the concentrate withhigh-purity ethylene in a ratio of approximately 1:4000. Thiscan be done by adding the calc
45、ulated amount of the concentrateand high purity ethylene to an evacuated cyclinder using thegas-blending apparatus (Fig. 2). Use a source of high-pressure,high-purity ethylene equipped with a needle valve and apressure gage capable of accurately measuring the pressure ofthe blend as the ethylene is
46、added to the cylinder containing theconcentrate. Add the calculated amount of ethylene; warm oneend of the cylinder to ensure mixing of the blend. Allow thetemperature to reach equilibrium before recording the finalpressure on the cylinder. Prepare at least three calibrationsamples containing the co
47、mpounds to be determined over therange of concentration desired in the products to be analyzed.9.2 Calculation of Composition of Standard MixturesCalculate the exact ratio of the concentrate dilution withethylene by correcting the pressure of the ethylene added forthe compressibility of ethylene (Ta
48、ble 2). Multiply the dilutionratio or factor by the percentage of each component present inthe original concentrate (Table 1). These calculations give theamount of each component that has been added to thehigh-purity ethylene blend stock. The actual composition of thefinal blend must be ascertained
49、by making corrections for theimpurities present in the high-purity ethylene used for theblend stock. The amount of correction is determined by makingchromatograph runs on the high-purity ethylene and measuringthe peak heights of the impurities. These peak heights will beTABLE 1 Suggested Composition of a Concentrate of ImpuritiesUsed in Preparing Standard Mixtures for Calibration PurposesComponent PercentCarbon dioxide 10Methane 45Ethane 25Propylene 20D2505 88 (2010)3used in adjusting the calibration factors described in 9.3. Sincepeak height
