1、Designation: D 1016 05e2An American National StandardStandard Test Method forPurity of Hydrocarbons from Freezing Points1This standard is issued under the fixed designation D 1016; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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.e1NOTEEq 54 in 25.3 was corrected editorially in June 2006.e2NOTEEq 3 and Eq 39 were corrected editorially in September
3、 2007.1. Scope*1.1 This test method covers the sampling and determinationof purity of essentially pure compounds for which the freezingpoints for zero impurity and cryoscopic constants are given.2The compounds to which the test method is applicable are:(WarningExtremely flammable liquids and liquefi
4、ed gases.)n-butane 1,3-butadieneisobutane isoprene(2-methyl-1,3-butadiene)n-pentane benzeneisopentane toluene (methylbenzene)n-hexane ethylbenzenen-heptane o-xylene (1,2-dimethylbenzene)n-octane m-xylene (1,3-dimethylbenzene)2,2,4-trimethylpentane p-xylene (1,4-dimethylbenzene)methylcyclohexane styr
5、ene (ethenylbenzene)isobutene1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.3 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 s
6、tandard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Sections 1, 6, 8, and 10-26.NOTE 1This test method covers systems in which the impurities formwith the major component a substanti
7、ally ideal or sufficiently dilutesolution, and also systems which deviate from the ideal laws, providedthat, in the latter case, the lowering of the freezing point as a function ofthe concentration is known for each most probable impurity in the givensubstance.2. Referenced Documents2.1 ASTM Standar
8、ds:3D 1015 Test Method for Freezing Points of High-PurityHydrocarbons3. Summary of Test Method3.1 After measurement of the freezing point of the actualsample, purity can be calculated from the value of thedetermined freezing point and the values given for the freezingpoint for zero impurity and for
9、the applicable cryoscopicconstant or constants.43.2 For the equilibrium between an infinitesimal amount ofthe crystalline phase of the major component and a liquid phaseof the major component and one or more other components, thethermodynamic relation between the temperature of equilib-rium and the
10、composition of the liquid phase is expressed bythe equation:521n N1521n 1 2 N2! 5 Atf 02 tf!1 1 Btf 02 tf! 1 . (1)where:N1= mole fraction of the major component,1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of S
11、ubcommitteeD02.04.0D on Physical and Chemical Methods.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1949. Last previous edition approved in 2004 as D 101699(2004)e1.2Numerical constants in this test method were taken from the most recentlypublished data appear
12、ing in “Tables of Physical and Thermodynamic Properties ofHydrocarbons and Related Compounds,” or ASTM DS 4A, Physical Constants ofHydrocarbons C1to C10, or both, prepared by the American Petroleum Institute,Research Project 44.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or
13、contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4For a more complete discussion of this test method, see Glasgow, A. R., Jr.,Streiff, A. J., and Rossini, F. D., “Determination of th
14、e Purity of Hydrocarbons byMeasurement of Freezing Points,” Journal of Research, JRNBA, National Instituteof Standards and Technology, Vol 35, No. 6, 1945, p. 355.5For details, see Taylor, W. J., and Rossini, F. D., “Theoretical Analysis ofTime-Temperature Freezing and Melting Curves as Applied to H
15、ydrocarbons,”Journal of Research, JRNBA, Nat. Bureau Standards, Vol 32, No. 5, 1944, p. 197;also Lewis, G. N., and Randall, M., “Thermodynamics and the Free Energy ofChemical Substances,” 1923, pp. 237, 238, McGraw-Hill Book Co., New York, NY.1*A Summary of Changes section appears at the end of this
16、 standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.N2=(1N1) = sum of the mole fractions of all the othercomponents,tf= freezing point, in degrees Celsius, of the givensubstance (in which the mole fraction of the majorcomponent
17、is N1), defined as the temperature atwhich an infinitesimal amount of crystals of themajor component is in thermodynamic equilibriumwith the liquid phase (see Note 3 of Test MethodD 1015),tf0= freezing point for zero impurity, in degrees Celsius,for the major component when pure, that is, whenN1=1or
18、N2=0,A = first or main cryoscopic constant, in mole fractionper degree, andB = secondary cryoscopic constant, in mole fraction perdegree.Neglecting the higher terms not written in the brackets, Eq 1can be transformed to the equation:log10P 5 2.00000 2 A / 2.3026!tf 02 tf!1 1 Btf 02 tf!# (2)where:P =
19、 purity of the given substance in terms of mole percentof the major component.4. Significance and Use4.1 The experimental procedures and physical constantsprovided by this test method, when used in conjunction withTest Method D 1015, allow the determination of the purity ofthe material under test. A
20、 knowledge of the purity of thesehydrocarbons is often needed to help control their manufactureand to determine their suitability for use as reagent chemicalsor for conversion to other chemical intermediates or finishedproducts.5. Apparatus5.1 Sampling Apparatus, as shown in Fig. 1, for withdraw-ing
21、 liquefied gases (for example, 1,3-butadiene) from pressurestorage cylinders.5.2 Distilling Apparatus, as shown in Fig. 2, for removingsmall amounts of polymer from low-boiling compounds (forexample, 1,3-butadiene) by simple distillation at atmosphericpressure.5.3 Distilling Apparatus, as shown in F
22、ig. 3, for removingsmall amounts of polymer from compounds with boiling pointsnear room temperature (for example, isoprene) by distillationat atmospheric pressure.5.4 Vacuum Distilling Apparatus and Transfer Trap,asshown in Fig. 4, for removing dissolved air and large amountsof polymer from a compou
23、nd (for example, 1,3-butadiene orstyrene), by repeated freezing and evacuation, followed bydistillation of the compound in vacuum in a closed system.6. Materials6.1 Carbon Dioxide RefrigerantSolid carbon dioxide in asuitable liquid. (WarningExtremely cold (78.5C). Liber-ates heavy gas which can caus
24、e suffocation. Contact with skincauses burns or freezing, or both. Vapors can react violentlywith hot magnesium or aluminum alloys.) Acetone isrecommended.(WarningExtremely flammable. Harmful ifinhaled. High concentrations can cause unconsciousness ordeath. Contact can cause skin irritation and derm
25、atitis. Userefrigerant bath only with adequate ventilation!)6.2 Liquid Nitrogen or Liquid Air(WarningExtremelycold. Liberates gas which can cause suffocation. Contact withskin causes burns or freezing, or both. Vapors can reactviolently with hot magnesium or aluminum alloys.) For use asa refrigerant
26、. If obtainable, liquid nitrogen is preferable be-cause of its safety.6.2.1 Use liquid nitrogen refrigerant only with adequateventilation. If liquid air is used as a refrigerant, it is imperativethat any glass vessel containing hydrocarbon or other combus-tible compound and immersed in liquid air be
27、 protected with asuitable metal shield. The mixing of a hydrocarbon or othercombustible compound with liquid air due to the breaking of aglass container would almost certainly result in a violentexplosion. If liquid nitrogen is used as a refrigerant, nohydrocarbon sample should ever be permitted to
28、cool below thecondensation temperature of oxygen (183C at atm). Thiswould not be likely to occur in normal operation, but mightoccur if the apparatus were left unattended for some time.7. Procedure7.1 Measure the freezing point as described in Test MethodD 1015, using the modifications and constants
29、 given in Sec-tions 8-26 of this test method for the specific compounds beingexamined.NOTE 2The estimated uncertainty in the calculated value of the purityas referred to in Sections 8-26 is not equivalent to the precision defined inRR: D02-1007.8. n-Butane6(WarningExtremely flammable liquefiedgas un
30、der pressure. Vapor reduces oxygen available forbreathing.)8.1 Determine the freezing point from freezing curves, withthe cage stirrer, with a cooling bath of liquid nitrogen (or liquidair), with a cooling rate of 0.3 to 0.8C/min for the liquid nearthe freezing point, and with crystallization induce
31、d immedi-ately below the freezing point by means of a cold rod.8.2 The method of obtaining the samples shall be asfollows: Assemble the apparatus for obtaining the sample asshown in Fig. 1, but with no lubricant on the ground-glassjoints and with the valve at the bottom of the cylinder, so thatsampl
32、ing is from the liquid phase. Attach to C an absorptiontube containing anhydrous calcium sulfate or other suitabledesiccant (except magnesium perchlorate) so that water is notintroduced into the system (Note 3). Fill the flask F with thecarbon dioxide refrigerant to within about 51 mm (2 in.) of the
33、top. After about 20 or 30 min, when the system will havecooled sufficiently, remove the absorption tube and begin thecollection of liquid n-butane by opening the valve K andadjusting the needle valve J so that the sample is collected ata rate of 1 to 2 mL (liquid)/min in the condensing tube E.NOTE 3
34、However, if some water does condense with the hydrocarbon,6For further details, see Glasgow, A. R., Jr., et al. “Determination of Purity byMeasurement of Freezing Points of Compounds Involved in the Production ofSynthetic Rubber,” Analytical Chemistry, ANCHA, Vol 20, 1948, p. 410.D101605e22the freez
35、ing point will not be affected significantly because of theextremely low solubility of water in the hydrocarbon at the freezing pointof the latter.8.3 Assemble the freezing point apparatus. Place the cool-ing bath in position around the freezing tube (O in Fig. 1 ofTest Method D 1015), letting the t
36、emperature as read on theplatinum thermometer reach about 80C when all the samplehas been collected.8.4 When 50 mL of liquid (temperature about 80C) hasbeen collected in the condensing tube, close the valve K (Fig.1) and allow the liquid which has collected at I to warm andtransfer to the condensing
37、 tube (Note 4). Replace the attachingtubes G and D on the condensing tube by caps. The liquidsample is now ready for introduction into the freezing tube (Oin Fig. 1 of Test Method D 1015).NOTE 4In case the original sample contained water, there will remainat I some water that may be discarded after
38、the hydrocarbon portion hasbeen collected as outlined above.8.5 When the temperature of the platinum thermometer isnear 80C, remove the condensing tube (E in Fig. 1) from theDewar flask. Wrap a cloth around the upper portion of thecondensing tube (for ease of handling and for preventing therefrigera
39、ting liquid from contaminating the sample on pour-ing), and after removing the caps on the condensing tube, raisethe stopper holding the platinum thermometer, and pour theAThree-way T stopcock, borosilicate glass (similar to Corning Pyrex No. 7420).BConnection to vacuum for purging and for evacuatin
40、g system CDEGHI.CCapillary tube for venting, to which drying tube is also connected.DJoint, standard taper, 12/30, borosilicate glass.ECondensing tube, borosilicate glass.FDewar flask, 1-qt size, borosilicate glass (similar to American Thermos Bottle Co. No. 8645).GTubing, borosilicate glass, 10 mm
41、in outside diameter, with spherical ground-glass joints, 18/7.HTubing, silicate glass, 10 mm in outside diameter, with spherical ground-glass joints, 18/7.IMetal connection, brass spherical male joint at one end fitting to connection to needle valve at other end.JNeedle valve, brass.KValve on cylind
42、er containing hydrocarbon material.LStandard cylinder containing hydrocarbon material.MFitting to connect needle valve J to valve K on cylinder.FIG. 1 Apparatus for Obtaining SampleD101605e23sample through the tapered male outlet of the condensing tubeinto the freezing tube (O in Fig. 1 of Test Meth
43、od D 1015).Quickly replace the stopper holding the platinum thermometer,and start the stirrer, with dry air flowing into the upper portionof the freezing tube through M (Fig. 1 of Test Method D 1015).8.6 Because the material is normally gaseous at roomtemperature, care should be taken in disposing o
44、f the samplesafely.8.7 For n-butane, the freezing point for zero impurity, in airat 1 atm, is as follows:tf 05 138.362 6 0.025C (3)and the cryoscopic constants are:A 5 0.03085 mole fraction/C and (4)B 5 0.0048 mole fraction/C. (5)8.8 The cryoscopic constants given in 8.7 are applicable tosamples of
45、n-butane having a purity of about 95 mole % orbetter, with no one impurity present in an amount that exceedsits eutectic composition with the major component.8.9 The estimated uncertainty in the calculated value of thepurity is as follows, in mole %:Calculated Purity,mole %Uncertainty, plus orminus,
46、 mole %Over 99.5 0.0899.0 to 99.5 0.0998 to 99 0.1097 to 98 0.1296 to 97 0.1595 to 96 0.209. Isobutane6(WarningExtremely flammable gas underpressure. Vapor reduces oxygen available for breathing.)9.1 Determine the freezing point from freezing curves withthe cage stirrer, with a cooling bath of liqui
47、d nitrogen (or liquidair), with a cooling rate of 0.3 to 0.8C/min for the liquid nearthe freezing point, and with crystallization induced immedi-ately below the freezing point by means of a cold rod.9.2 Obtain the samples as follows: Assemble the apparatusfor obtaining the sample as shown in Fig. 1,
48、 but with nolubricant on the ground-glass joints and with the valve at thebottom of the cylinder, so that sampling is from the liquidphase. Attach to C an absorption tube containing anhydrouscalcium sulfate or other suitable desiccant (except magnesiumperchlorate) so that water is not introduced int
49、o the systemCDewar vessel, 1-qt capacity, borosilicate glass.DClamp.EDistilling tube, borosilicate glass, 25 mm in outside diameter.FStandard-taper ground-glass joint, 24/40 borosilicate glass.GTubing, 10 mm in outside diameter, borosilicate glass.H, H8Spherical ground-glass joints, 18/7, borosilicate glass.ITubing, 6 mm in outside diameter, borosilicate glass.JReceiver, 35 mm in outside diameter, 150 mm in length, borosilicate glass.FIG. 2 Simple Distilling Apparatus for Normally GaseousSubstancesAStandard-taper, ground-gl
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