UOP 744-2006 Aromatics in Hydrocarbons by GC.pdf

1、 IT IS THE USERS RESPONSIBILITY TO ESTABLISH APPROPRIATE PRECAUTIONARY PRACTICES AND TO DETERMINE THE APPLICABILITY OF REGULATORY LIMITATIONS PRIOR TO USE. EFFECTIVE HEALTH AND SAFETY PRACTICES ARE TO BE FOLLOWED WHEN UTILIZING THIS PROCEDURE. FAILURE TO UTILIZE THIS PROCEDURE IN THE MANNER PRESCRIB

2、ED HEREIN CAN BE HAZARDOUS. MATERIAL SAFETY DATA SHEETS (MSDS) OR EXPERIMENTAL MATERIAL SAFETY DATA SHEETS (EMSDS) FOR ALL OF THE MATERIALS USED IN THIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). COPYRIGHT 1974, 1977, 1986, 1998, 2004, 2006 UOP

3、 LLC. All rights reserved. Nonconfidential UOP Methods are available from ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA. The UOP Methods may be obtained through the ASTM website, www.astm.org, or by contacting Customer Service at serviceastm.org, 610.8

4、32.9555 FAX, or 610.832.9585 PHONE. Aromatics in Hydrocarbons by GC UOP Method 744-06 Scope This method is for determining individual C6through C10aromatic compounds in petroleum distillates or aromatic concentrates having a final boiling point of 210C or lower. C11and heavier aromatics are reported

5、 as a group. C10and heavier non-aromatics may interfere with the determination of benzene and toluene. When this occurs, benzene and toluene can be determined by ASTM Methods D 5443, D 5580, D 6729, or D 6839, or UOP Methods 690, or 870. Other applications for this method include the assay of any C1

6、0or lower boiling aromatics, such as benzene, toluene, mixed xylenes, etc. This method may also be used to provide a distribution of C8aromatics and/or C9and heavier aromatics to a value determined by a different method. When used for any of the above applications, the limit of quantitation for a si

7、ngle aromatic component is 0.01 mass-%. References ASTM Method D 4307, “Preparation of Liquid Blends for Use as Analytical Standards,” www.astm.org ASTM Method D 5443, “Paraffin, Naphthene, and Aromatic Hydrocarbon Type Analysis in Petroleum Distillates Through 200C by Multidimensional Gas Chromatog

8、raphy,” www.astm.org ASTM Method D 5580, “Determination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9and Heavier Aromatics, and Total Aromatics by Gas Chromatography,” www.astm.org ASTM Method D 6729, “Determination of Individual Components in Spark Ignition Engine Fuels by 100 Meter C

9、apillary High Resolution Gas Chromatography,” www.astm.org ASTM Method D 6839, “Hydrocarbon Types, Oxygenated Compounds, and Benzene in Spark Ignition Engine Fuels by Gas Chromatography,” www.astm.org Scanlon, J. T. and Willis, D. E., Journal of Chromatographic Science, 23, 333-340 (1985) UOP Method

10、 690, “Octanes and Lower Boiling Hydrocarbons in Olefin-Free Gasolines by GC,” www.astm.org UOP Method 870, “Carbon Number Distribution of Paraffins, Naphthenes, and Aromatics by GC,” www.astm.org Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement with Monique

11、 Tyree (ASTMIHS Account); Tue Aug 8 10:43:31 EDT 20062 of 11 744-06 UOP Method 999, “Precision Statements in UOP Methods,” www.astm.org Outline of Method The sample is injected into a gas chromatograph that is equipped with a flame ionization detector (FID) and a fused silica capillary column intern

12、ally coated with cross-linked polyethylene glycol. The mass-% composition of the sample is obtained by the normalization of peak areas after relative response factors are applied to correct for detector mass response differences. Alternatively, selected aromatic components, e.g., C8aromatics, may be

13、 normalized to their sum as determined by another technique. Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Balance, readability 0.1-mg Chromatographic column, 60 m of 0.32-mm ID fused silica capillary, internally

14、coated to a film thickness of 0.5-m with cross-linked polyethylene glycol, Restek, Cat. No. 10642 Gas chromatograph, capable of multiple temperature ramping, built for capillary column chromatography utilizing a split injection system, having a glass injection port insert, and equipped with a flame

15、ionization detector that will give a minimum peak height response of 5 times the background noise for 0.01 mass-% of benzene when operated at the recommended conditions. Electronic pressure control (EPC) is recommended. Agilent Technologies, Model 6890 Data system, or electronic integrator, for obta

16、ining peak areas. This device must integrate areas at a sufficiently fast rate so that narrow peaks typically resulting from use of a capillary column can be accurately measured. Agilent Technologies, ChemStation Leak detector, gas, Alltech Associates, Cat. No. 21-250 Regulator, air, two-stage, high

17、 purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-590 Regulator, hydrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-350 Regulator, nitrogen or helium, two-stage, high purity, delivery pressure range 30-70

18、0 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Sample injector, any syringe or injector capable of injecting a 0.5-L volume of sample. An automatic injection device is recommended. Agilent Technologies, Model 7683 Reagents and Materials References to catalog numbers and suppliers are included a

19、s a convenience to the method user. Other suppliers may be used. Air, total hydrocarbons less than 2 ppm as methane Benzene, 99.9%, Aldrich Chemical, Cat. No. 27,070-9 Gas purifier, for hydrogen, to remove oxygen and moisture from carrier gas, VICI Mat/Sen, Cat. No. P200-1 Copyright by ASTM Intl (al

20、l rights reserved);Reproduction authorized per License Agreement with Monique Tyree (ASTMIHS Account); Tue Aug 8 10:43:31 EDT 20063 of 11 744-06 n-Heptane, 99+%, Aldrich Chemical, Cat. No. 27,051-2 Hydrogen, zero-gas, 99.95% minimum purity, total hydrocarbons less than 0.5 ppm as methane 1-Methyl-2-

21、ethylbenzene, 99%, Chemsampco, Cat. No. 2900.00 Methylindane isomers, if needed for peak identification, AccuStandard, special order Nitrogen or helium, zero-gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane, used for detector makeup gas Syringe, replacement, for recommende

22、d sample injector, 5-L, Agilent Technologies, Cat. No. 5181-1273 1,2,3,4-Tetramethylbenzene, 99%, Chemsampco, Cat. No. 8490.00 Toluene, 99.8%, Aldrich Chemical, Cat. No. 27,037-7 Xylenes (C8aromatics), mixed, 98.5+%, Aldrich Chemical, Cat. No. 24,764-2 Procedure Chromatographic Technique 1. Install

23、the gas purifier in the supply line between the carrier gas source and the carrier gas inlet on the gas chromatograph. Column life is significantly reduced if the gas purifier is not used. 2. Install the fused silica capillary column in the gas chromatograph. CAUTION: Hydrogen carrier gas leakage in

24、to the confined volume of the column oven can cause a violent explosion. It is, therefore, mandatory to check for leaks each time a connection is made and periodically thereafter. 3. Establish the recommended operating conditions as given in Table 1. Other conditions may be used provided they produc

25、e the required sensitivity and chromatographic separations equivalent to those shown in the Typical Chromatogram. Figures 1 through 3 constitute a single chromatogram. 4. Program the column oven temperature to 210C and maintain this temperature until a stable baseline has been obtained at the requir

26、ed sensitivity. 5. Cool the column oven to a stabilized 50C. 6. Thoroughly mix the sample. 7. Inject nominally 0.5 L of sample into the gas chromatograph and start the integrator and the column oven programming sequence. The injection sequence of a GC is typically automated, performing the injection

27、 and starting the integrator and column temperature program simultaneously. 8. Identify the components of interest by comparing the resultant chromatogram to the Typical Chromatogram. All unidentified components eluting before n-butylbenzene are defined as non-aromatics. All unidentified components

28、 eluting after n-butylbenzene are defined as C11+ aromatics. Olefinic C9and C10aromatics, e.g., substituted styrenes, if present, elute after n-butylbenzene and may elute under other identified components or may be included in the C11+ aromatics. 2-Methyl-naphthalene, 1-Methylnaphthalene, the ethyln

29、apthalene isomer, and three dimethylnaphthalene isomers are identified on the Typical Chromatogram, but are included in the C11+ aromatics for calculation and reporting purposes. They can be reported separately if they are clearly identifiable. Copyright by ASTM Intl (all rights reserved);Reproducti

30、on authorized per License Agreement with Monique Tyree (ASTMIHS Account); Tue Aug 8 10:43:31 EDT 20064 of 11 744-06 Methylindanes co-elute with other C10and C11aromatics. Identify and report these components only when they are known to be present in concentrations significantly higher than the inter

31、fering compounds. Use pure compounds or GC-MS to confirm identifications. Any unidentified component can be identified by experiment and reported separately, if required. Additional pure compounds can be obtained and analyzed, or GC-MS or other techniques may be used 1,3-Diethylbenzene and 1-methyl-

32、2-isopropylbenzene co-elute at some concentrations. Table 1 Recommended Operating Conditions Carrier gas hydrogen Column head pressure 68 kPa gauge (10 psig) Mode constant pressureAEquivalent flow 50C 2.1 mL/min Equivalent linear velocity 50C 35 cm/sec Split flow 100 mL/min Injection port temperatur

33、e 230C Column temperature program Initial temperature 50C Initial time 5 min Programming rate A 8C/min Intermediate temperature A 100C Intermediate time A 0 min Programming rate B 2C/min Intermediate temperature B 120C Intermediate time B 0 min Programming rate C 20C/min Final temperature 210C Final

34、 time 40 min Detector FID Temperature 240C Hydrogen flow rateB32 mL/min Air flow rateB350 mL/min Make up gas nitrogen or helium Makeup flow rateB32 mL/min Sample size 0.5 L AConstant flow mode is also used. Confirm separations and retention times. BConsult the manufacturers instrument manual for sug

35、gested flow rates. Calibration Relative response factors are required to relate the peak areas of sample components to mass-% since all the components do not respond equally in a flame ionization detector. 1. Prepare a calibration blend as described in ASTM Method D 4307 to contain 25 mass-% n-hepta

36、ne, 15 mass-% benzene, 20 mass-% toluene, 20 mass-% mixed xylenes, 10 mass-% 1-methyl-2-ethylbenzene, and 10 mass-% 1,2,3,4-tetramethylbenzene. The composition of the calibration blend is given based upon a broad spectrum of samples to be analyzed. If typical samples to be analyzed are all of a simi

37、lar composition, but different from the listed Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement with Monique Tyree (ASTMIHS Account); Tue Aug 8 10:43:31 EDT 20065 of 11 744-06 concentrations, prepare the calibration blend with component concentrations that m

38、ore closely approximate the typical sample. 2. Run the calibration blend three times as described in Steps 7 through 8 under Chromatographic Technique. A calibration blend is run when the method is initially set up, thereafter when changes are made to the equipment, and periodically to verify proper

39、 calibration. 3. Identify the peaks and average the individual peak areas from the triplicate runs. The peak areas from each of the three runs should not deviate from the average by more than 3% of the value. If greater deviations occur, make certain that there are no problems with the equipment or

40、technique, and then make further runs until the required repeatability is obtained on three consecutive runs. A calibration blend is run when the method is initially set up and thereafter when changes have been made to the equipment or periodically to verify proper calibration. 4. Use the average pe

41、ak areas to calculate the relative response factor for each component to three decimal places, using n-heptane as a reference, and Equation 1. F = ABCD(1) where: A = concentration of the component or group of components in the calibration blend, mass-% B = average peak area of n-heptane C = concentr

42、ation of n-heptane in the blend, mass-% D = average peak area for the component or group of components F = relative response factor for the component or group of components Aromatic hydrocarbons have a greater response by weight than non-aromatics, with benzene having the highest relative response,

43、and thus, the lowest (numerical) relative response factor. Therefore, the relative response factors determined will be proportional in the order: benzene toluene mixed xylenes 1-methyl-2-ethylbenzene 1,2,3,4-tetramethylbenzene n-heptane. If the determined relative response factors are not proportion

44、al in that order, recheck the instrument hardware, particularly the inlet system, the operating conditions, the detector and integrator linearity, and the blend preparation. Calculated relative response factors should be similar to the theoretical relative response factors shown in Table 2. The theo

45、retical relative response factors were calculated using the effective carbon number (ECN) concept as described by Scanlon and Willis. If the determined relative response factors differ by more than 5% from those shown in Table 2, recheck the apparatus, operating conditions, and blend preparation pro

46、cedures. Table 2 Theoretical Relative Response Factors n-Heptane 1.000 Benzene 0.909 Toluene 0.919 Xylenes 0.927 1Methyl-2-ethylbenzene 0.933 1,2,3,4-Tetramethylbenzene 0.938 Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement with Monique Tyree (ASTMIHS Accoun

47、t); Tue Aug 8 10:43:31 EDT 20066 of 11 744-06 Use the relative response factor of n-heptane for all non-aromatics, the relative response factor of 1-methyl-2-ethylbenzene for the C9aromatics, and the relative response factor of 1,2,3,4,-tetramethylbenzene for all C10and C11+ aromatics. Calculations

48、Total Sample Calculate the concentration of each component or group of components using Equation 2. Component, mass- % = 100 FGN(2) where: F = previously defined, Equation 1 G = peak area of individual component or group of components in the sample N = sum of the products, FG, of all the components

49、and groups of components in the sample; also expressed as =n1iiiGF 100 = factor to convert to mass-% Distribution of Selected Components Normalize a selected group of aromatic components to a predetermined value using Equation 3. Component, mass - % = FGMZ(3) where: F = previously defined, Equation 1 G = previously defined, Equation 2 M = value to which the selected group is to be normalized, mass-% Z = sum of the products, FG, of all of the selected group of peaks; also expressed as =n1iiiGF Report