1、Designation: D 5292 99 (Reapproved 2004)An American National StandardStandard Test Method forAromatic Carbon Contents of Hydrocarbon Oils by HighResolution Nuclear Magnetic Resonance Spectroscopy1This standard is issued under the fixed designation D 5292; the number immediately following the designa
2、tion indicates the year oforiginal 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 dete
3、rmination of the aro-matic hydrogen content (Procedures A and B) and aromaticcarbon content (Procedure C) of hydrocarbon oils usinghigh-resolution nuclear magnetic resonance (NMR) spectrom-eters. Applicable samples include kerosenes, gas oils, mineraloils, lubricating oils, coal liquids, and other d
4、istillates that arecompletely soluble in chloroform at ambient temperature. Forpulse Fourier transform (FT) spectrometers, the detection limitis typically 0.1 mol % aromatic hydrogen atoms and 0.5 mol %aromatic carbon atoms. For continuous wave (CW) spectrom-eters, which are suitable for measuring a
5、romatic hydrogencontents only, the detection limit is considerably higher andtypically 0.5 mol % aromatic hydrogen atoms.1.2 The reported units are mole percent aromatic hydrogenatoms and mole percent aromatic carbon atoms.1.3 This test method is not applicable to samples containingmore than 1 mass
6、% olefinic or phenolic compounds.1.4 This test method does not cover the determination of thepercentage mass of aromatic compounds in oils since NMRsignals from both saturated hydrocarbons and aliphatic sub-stituents on aromatic ring compounds appear in the samechemical shift region. For the determi
7、nation of mass or volumepercent aromatics in hydrocarbon oils, chromatographic, ormass spectrometry methods can be used.1.5 The values stated in SI units are to be regarded as thestandard.1.6 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is
8、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. Specific precau-tionary statements are given in 7.2 and 7.4.2. Referenced Documents2.1 ASTM Standards:2D 3238 Test Method for
9、Calculation of Carbon Distributionand Structural Group Analysis of Petroleum Oils by then-d-M MethodD 3701 Test Method for Hydrogen Content of AviationTurbine Fuels by Low Resolution Nuclear Magnetic Reso-nance SpectrometryD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsE 386 P
10、ractice for Data Presentation Relating to High-Resolution Nuclear Magnetic Resonance (NMR) Spectros-copy2.2 Energy Institute Methods:IP Proposed Method BD Aromatic Hydrogen and AromaticCarbon Contents of Hydrocarbon Oils by High ResolutionNuclear Magnetic Resonance Spectroscopy33. Terminology3.1 Def
11、initions of Terms Specific to This Standard:3.1.1 aromatic carbon contentmole percent aromatic car-bon atoms or the percentage of aromatic carbon of the totalcarbon:aromatic carbon content 5 1003 aromatic carbon atoms!/total carbon atoms! (1)3.1.1.1 DiscussionFor example, the aromatic carbon con-ten
12、t of toluene is 100 3 (6/7) or 85.7 mol % aromatic carbonatoms.3.1.2 aromatic hydrogen contentmole percent aromatichydrogen atoms or the percentage of aromatic hydrogen of thetotal hydrogen:aromatic hydrogen content 5 1003 aromatic hydrogen atoms!/total hydrogen atoms! (2)1This test method is under
13、the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04 on Absorption Spectroscopic Methods.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1992. Last previous edition approved in 1999 as
14、D 5292 99.2For 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 Document Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish
15、St., London, WIG 7AR,U.K.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2.1 DiscussionFor example, the aromatic hydrogencontent of toluene is 100 3 (5/8) or 62.5 mol % aromatichydrogen atoms.3.2 Definitions of chemical shift (re
16、ported in parts permillion (ppm), internal reference, spectral width, and otherNMR terminology used in this test method can be found inPractice E 386.3.3 Chloroform-d refers to chloroform solvent in whichhydrogen is replaced by deuterium, the heavier isotope ofhydrogen. Chloroform-d is available fro
17、m a variety of chemi-cal and isotope suppliers.4. Summary of Test Method4.1 Hydrogen (1H) nuclear magnetic resonance (NMR)spectra are obtained on solutions of the sample inchloroform-d, using a CW or pulse FT high-resolution NMRspectrometer. Carbon (13C) NMR spectra are obtained onsolutions of the s
18、ample in chloroform-d using a pulse FThigh-resolution NMR spectrometer. Tetramethylsilane is pre-ferred as an internal reference in these solvents for assigningthe 0.0 parts per million (ppm) chemical shift position inboth1H and13C NMR spectra.4.2 The aromatic hydrogen content of the sample is mea-s
19、ured by comparing the integral for the aromatic hydrogenband in the1H NMR spectrum (5.0 to 10.0 ppm chemical shiftregion) with the sum of the integrals for both the aliphatichydrogen band (0.5 to 5.0 ppm region) and the aromatichydrogen band (5.0 to 10.0 ppm region).4.3 The aromatic carbon content o
20、f the sample is measuredby comparing the integral for the aromatic carbon band inthe13C spectrum (100 to 170 ppm chemical shift region) withthe sum of the integrals for both the aliphatic carbon band (10to 70 ppm region) and the aromatic carbon band (100 to 170ppm region).4.4 The integral of the aro
21、matic hydrogen band must becorrected for the NMR absorption line due to residual chloro-form (7.25 ppm chemical shift) in the predominantlychloroform-d solvent.4.5 The integrals of the aliphatic hydrogen band and of thealiphatic carbon band must be corrected for the NMR absorp-tion line due to the i
22、nternal chemical shift reference tetrameth-ylsilane (0.0 ppm chemical shift in both1H and13C spectra).5. Significance and Use5.1 Aromatic content is a key characteristic of hydrocarbonoils and can affect a variety of properties of the oil including itsboiling range, viscosity, stability, and compati
23、bility of the oilwith polymers.5.2 Existing methods for estimating aromatic contents usephysical measurements, such as refractive index, density, andnumber average molecular weight (seeTest Method D 3238)orinfrared absorbance4and often depend on the availability ofsuitable standards. These NMR proce
24、dures do not requirestandards of known aromatic hydrogen or aromatic carboncontents and are applicable to a wide range of hydrocarbon oilsthat are completely soluble in chloroform at ambient tempera-ture.5.3 The aromatic hydrogen and aromatic carbon contentsdetermined by this test method can be used
25、 to evaluate changesin aromatic contents of hydrocarbon oils due to changes inprocessing conditions and to develop processing models inwhich the aromatic content of the hydrocarbon oil is a keyprocessing indicator.6. Apparatus6.1 High-Resolution Nuclear Magnetic ResonanceSpectrometerA high-resolutio
26、n continuous wave (CW) orpulse Fourier transform (FT) NMR spectrometer capable ofbeing operated according to the conditions in Table 1 and Table2 and of producing peaks having widths less than the frequencyranges of the majority of chemical shifts and coupling con-stants for the measured nucleus.6.1
27、.11H NMR spectra can be obtained using either CW orpulse FT techniques but13C measurements require signalaveraging and, therefore, currently require the pulse FT tech-nique. Low resolution NMR spectrometers and procedures arenot discussed in this test method (see Test Method D 3701 foran example of
28、the use of low resolution NMR).6.2 Tube TubesUsuallya5or10mmoutside diametertube compatible with the configuration of the CW or pulse FTspectrometer.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall re
29、agents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use.7.2 Chloroform-dFor
30、1H NMR, chloroform-d must con-tain less than 0.2 vol % residual chloroform. Care must betaken not to contaminate the solvent with water and other4Brandes, G., “The Structural Groups of Petroleum Fractions. I. StructuralGroupAnalysis With the Help of Infrared Spectroscopy,” Brennstoff-Chemie Vol 37,1
31、956, p. 263.5“Reagent Chemicals, American Chemical Society Specification.” AmericanChemical Society, Washington, D.C. For suggestions on the testing of reagents notlisted by the American Chemical Society, see “Analar Standards for LaboratoryU.K. Chemicals,” BDH Ltd., Poole, Dorset, and the “United S
32、tates Pharmacopeia.”TABLE 1 Sample and Instrument Conditions for ContinuousWave (CW) Measurements of1H NMR SpectraSolvent Chloroform-dSample concentration Up to 50 % v/v for distillable oilsSample temperature Instrument ambientInternal lock NoneSample spinning rate As recommended by manufacturer, ty
33、pically 20 Hzr-f Power level As recommended by instrument manufacturerSignal to noise level A minimum of 5:1 for the maximum height of thesmaller integrated absorption bandChemical shift reference Preferably tetramethylsilane (0.0 ppm) at nogreater than 1 vol % concentrationIntegration Integrate ove
34、r the range 0.5 to 5.0 ppm for thealiphatic band and 5.0 to 10.0 ppm for the aromaticbandD 5292 99 (2004)2extraneous materials. (WarningHealth hazard. Highly toxic.Cancer suspect agent. Can be fatal when swallowed andharmful when inhaled. Can produce toxic vapors whenburned.)7.3 Tetramethylsilane, A
35、merican Chemical Society (ACS)reagent internal chemical shift reference for1H and13C NMRspectra. (WarningFlammable liquid.)7.4 Chromium (III) 2,4-Pentanedionate, relaxation reagentfor13C NMR spectra, typically 97 % grade.8. Sampling8.1 It is assumed that a representative sample acquired by aprocedur
36、e of Practice D 4057 or equivalent has been receivedin the laboratory. If the test is not to be conducted immediatelyupon receipt of the sample, store in a cool place until needed.8.2 A minimum of approximately 10 mL of sample isrequired for this test method. This should allow duplicatedetermination
37、s, if desired.8.3 All samples must be homogeneous prior to subsam-pling. If any suspended particles present are attributable toforeign matter such as rust, filter a portion of the sample to betested through a small plug of glass wool, contained in a cleansmall funnel, into a clean and dry vial or NM
38、R sample tubecontaining chloroform-d.8.4 If the sample contains waxy materials, heat the samplein the container to approximately 60C and mix with ahigh-shear mixer prior to sampling. It may be necessary totransfer a portion of the sample to an NMR tube containingchloroform-d by means of a pipet whic
39、h has been heated toapproximately 60C to maintain the homogeneity of thesample.8.5 For a valid test result, samples must be completelysoluble in chloroform-d. Check to ensure that the final solutionis homogeneous and free of undissolved particles.9. Procedures9.1 Three different procedures are descr
40、ibed in this sectionfor determining the aromatic hydrogen content, (see 9.6)Procedures A and B (see 9.7), and the aromatic carbon contentof hydrocarbon oils, Procedure C (see 9.8).9.2 The procedure selected by the analyst will depend on theavailable NMR instrumentation and on whether an aromatichydr
41、ogen or aromatic carbon content is of greater value inevaluating the characteristics of the hydrocarbon oil.9.3 Appendix X1 and Practice E 386 should be used inconjunction with the NMR spectrometer manufacturers in-structions in order to ensure optimum performance of the NMRinstrument in the applica
42、tion of these procedures.9.4 If tetramethylsilane is used as an internal chemical shiftstandard, prepare a 1 % v/v TMS in solvent solution by addingtetramethylsilane to chloroform-d solvent. Since TMS is veryvolatile, this solution should be refrigerated or replaced if thecharacteristic absorption d
43、ue to TMS is no longer evident inthe1Hor13C NMR spectrum.9.5 If it is inconvenient to prepare the test solution directlyin the NMR sample tube as suggested in the followingprocedures, the test solution can be prepared in a small vial andtransferred into the NMR sample tube after solvent additionand
44、sample dissolution. Care should be exercised to ensure thatthe final solution concentrations are not different from thoseindicated in the procedures and that no contamination occursduring the transfer process.9.6 Procedure A1H NMR Measurements Using a Con-tinuous Wave (CW) NMR Spectrometer:TABLE 2 S
45、ample and Instrument Conditions for Pulse FourierTransform Measurements of1H and13C NMR SpectraSolvent:1H NMR Chloroform-d13C NMR Chloroform-dSample concentration:1H NMR Must be optimized for the instrument in use butmay be as high as 5 % v/v13C NMR Up to 50 % v/v for petroleum distillates and 30 %v
46、/v for coal liquidsRelaxation agent Chromium (III) 2,4-pentanedionate recommendedfor13C NMR solutions only. Where used, a 20 mMsolution (about 10 mg per mL)Sample temperature Instrument ambientInternal lock Deuterium (when chloroform-d is used for1HNMR)Sample spinning rate As recommended by manufact
47、urer, typically 20 Hz1H Decoupling Only for13C NMR. Broadband over the whole ofthe1H frequency range, gated on during13C dataacquisition only with a decoupler rise time lessthan2m/sPulse flip angle Approximately 30Sequence delay time:1HNMR10s13CNMR3swithand 60 s without relaxationagentMemory size fo
48、racquisition:Choose to give a minimum digitizing rate of 0.5Hz/point for1H and 1.2 Hz/point for13C NMR. Ifnecessary, increase memory size and zero fillSpectral width:1H NMR At least 15 ppm in frequency and centered, asclose as possible, to the 5 ppm chemical shiftvalue13C NMR At least 250 ppm in fre
49、quency and centered, asclose as possible, to the 100 ppm chemical shiftvalueFilter bandwidth Set to be equal to or greater than the spectralwidth and as permitted by the instruments filterhardwareExponential linebroadeningSet at least equal to the digitizing rateSignal to noise levels:1H NMR A minimum of 20:1 for the maximum height of thesmaller integrated band13C NMR A minimum of 60:1 for the maximum height of thechloroform-d resonance appearing between 75 and80 ppm on the chemical shift scaleChemical shift reference:1H NMR Preferably tetramethylsilane (0.0
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