UOP 960-2016 Trace Oxygenated Hydrocarbons in Gaseous LPG and Liquid Hydrocarbon Streams 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. SAFETY DATA SHEETS (SDS) 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 1998, 2006, 2016 UOP LLC. All rights reserved. N

3、onconfidential UOP Methods are available from ASTM International, 100 Barr Harbor Drive, P.O. 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, 610.832.9555 FAX, or 610.832.95

4、85 PHONE. Trace Oxygenated Hydrocarbons in Gaseous, LPG and Liquid Hydrocarbon Streams by GC UOP Method 960-16 Scope This method is for determining trace levels of individual oxygenated hydrocarbons, with boiling points up to 138C, in refinery gas streams, C4 liquefied petroleum gas (LPG), light iso

5、merate and naphtha. Mono-oxygenated hydrocarbons determined include C1 through C5 alcohols, and C2 through C6 carbonyls and ethers. Di-oxygenated hydrocarbons determined include C2 through C4 methyl esters and 1,4-dioxane. The range of quantitation for individual oxygenates is 0.1 to 250 mass-ppm (m

6、g/kg). Inorganic compounds containing oxygen, such as water, carbon monoxide and carbon dioxide or other heteroatoms such as nitrogen, chlorine or sulfur are not determined. Unsaturated oxygenated hydrocarbons may be detected but are not identified. Certain oxygenated hydrocarbons are not separated

7、and are reported as composites. Some sulfur and nitrogen compounds are known to elute in the oxygenate region of the chromatogram. References ASTM Method D1657, “Density or Relative Density of Light Hydrocarbons by Pressure Hydrometer,” www.astm.org ASTM Method D2163, “Analysis of Liquefied Petroleu

8、m (LP) Gases and Propene Concentrates by Gas Chromatography,” www.astm.org ASTM Method D2598, “Calculation of Certain Physical Properties of Liquefied Petroleum (LP) Gases from Compositional Analysis,” www.astm.org ASTM Method D7423, “Determination of Oxygenates in C2, C3, C4, and C5 Hydrocarbon Mat

9、rices by Gas Chromatography and Flame Ionization Detection1,” www.astm.org ASTM Method D4052, “Density and Relative Density of Liquids by Digital Density Meter,” www.astm.org ASTM Practice D4307, “Preparation of Liquid Blends for Use as Analytical Standards,” www.astm.org UOP Method 373, “Compositio

10、n of C2 Through C5 Hydrocarbon Mixtures by Gas Chromatography, www.astm.org 2 of 16 960-16 UOP Method 999, “Precision Statements in UOP Methods,” www.astm.org Scanlon, J. T., and D. E. Willis. “Calculation of Flame Ionization Detector Relative Response Factors Using the Effective Carbon Number Conce

11、pt.“ Journal of Chromatographic Science 23.8 (1985): 333-40. Web. Outline of Method A repeatable volume of sample is injected into a specially modified gas chromatograph (GC) that is equipped with two megabore capillary columns operating at different temperatures. The first column, a non-polar colum

12、n, fractionates interfering sample components from the system. The second column, a selective Lowox column, separates and analyzes oxygenates. The non-polar column operates isothermally inside an auxiliary oven, and the Lowox column resides in the main GC oven. Initially, the columns are connected i

13、n series, and after the elution of components of interest from the non-polar column, the non-polar column is backflushed. The Lowox column is maintained in foreflush and temperature programmed, eluting compounds to a flame ionization detector (FID). Quantitative results are obtained by the external

14、standard method of quantitation wherein the peak areas for the components of interest are compared to peak areas of a calibration standard. Effective carbon number (ECN) is used to calculate the relative response factors of the oxygenated components based on the response factor of the reference mate

15、rial. See Table 2 for a list of commonly found compounds and composites. Oxygenates not commonly found but can be identified using a pure standard of the component are listed in Table 3. Using pures to calibrate each component will result in better accuracy. Apparatus References to catalog numbers a

16、nd suppliers are included as a convenience to the method user. Other suppliers may be used. Analyzer, Wasson ECE Instrumentation, Application No. UOP960. See Figure 1 for Analyzer configuration. Other vendors also supply similar systems. Confirm with the selected vendor that the required separations

17、 are provided for the specific sample types to be analyzed. The Wasson-ECE analyzer includes: Chromatographic column, 20 m x 530 m ID x 5 m MXT-1, Restek, Cat. No. 71812 Chromatographic column, 10 m x 530 m ID x 10 m Lowox, Agilent, Cat. No. CP8587 Gas chromatograph, capable of multiple temperature

18、ramping, built for capillary column chromatography utilizing a split injection system with electronic pressure control (EPC), having a glass injection port insert. Three channels of additional electronic pressure control is required. Agilent Technologies, Model 7890. Sample injector, syringe or inje

19、ctor capable of injecting a 4-L repeatable volume of sample. An automatic injection system is recommended, Agilent Technologies Model 7693A. Balance, readability 0.1-mg Electronic leak detector, Agilent gas leak detector, Agilent, Cat. No. G3388B Fittings, CGA, for blend cylinder, CGA No. 510, Mathe

20、son Tri-Gas Integrator, electronic, for obtaining peak areas. This device must be capable of graphically displaying chromatograms and peak integration, Agilent Chemstation or equivalent. Pipet bulb, 1-mL, Fisher Scientific, Cat. No. 03-448-25 3 of 16 960-16 Regulator, air, two-stage, high purity, Ma

21、theson Tri-Gas, Cat. No. SEQ3122A590 Regulator, hydrogen, two-stage, high purity, Matheson Tri-Gas, Cat. No. SEQ3122A350 Regulator, single-stage, non-corrosive for methyl ether, Sigma-Aldrich, Cat. No. Z146706 Regulator, nitrogen, two-stage, high purity, Matheson Tri-Gas, Model Cat. No. SEQ3122A580

22、Regulator, nitrogen, single stage, high purity, high pressure delivery to pressurize LPG sample and blend cylinders, Matheson Tri-Gas, Cat. No. SEQ3538A580 Syringe, 10-L, for qualitative mixture preparation, Hamilton 701NF, 2 required, Restek, Cat. No. 20167 Reagents and Materials References to cata

23、log numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Air, zero-gas, total hydrocarbons less than 2 ppm as methane Blend, gas, quantitative, certified standard, containing 100 mol-ppm of dimethyl ether in research grade propane, Matheson Tri-Gas. Bl

24、end, LPG, quantitative, certified standard, containing 10 mass-ppm of 2-butanone in research grade isobutane, contained in an aluminum Ultra-Line cylinder with a stainless steel valve, Matheson Tri-Gas. A 250-psig nitrogen head pressure should be maintained on the LPG blend. Bottle, glass, 500-mL, w

25、ith cap, for qualitative blend preparation, Fisher Scientific, Cat. No. FB800500 Cyclohexane, anhydrous, 99.5+%, Sigma-Aldrich, Cat. No. 227048. The anhydrous cyclohexane is kept under a nitrogen blanket between uses to prevent contamination. Gas purifier, hydrogen carrier gas purifier, VICI Metroni

26、cs, Cat. No. P200-1 Gas purifier, air (for detectors), VICI Metronics, Cat. No. P400-1 Gas purifier, nitrogen, for detector makeup gas, VICI Metronics, Cat. No. P300-1 Hydrogen, zero-gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane Inlet liner, Silicosleeve, 5.2 mm ID Stra

27、ight Inlet Liner for Agilent GCs equipped with split/splitless inlets, Restek, Cat. No. 21700-205 Methyl ethyl ketone (2-Butanone), 99.5%, Sigma-Aldrich, Cat. No. 270695 Nitrogen, zero-gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane Oxygenated hydrocarbons, Sigma-Aldrich,

28、 see Table 2 and Table 3 for Cat. Nos. Pipet, Pasteur, disposable, 146-mm, Fisher Scientific, Cat. No. 13-678-20A Vials, glass, 20-mL, with caps, Fisher Scientific, Cat. No. 03-337-14 Procedure The analyst is expected to be familiar with general laboratory practices, the technique of gas chromatogra

29、phy, mass spectrometry and the equipment being used. Dispose of used reagents, materials, and samples in an environmentally safe manner according to local regulations. 4 of 16 960-16 Sampling Obtain the sample by following the procedures described in ASTM Practice D 1265, “Sampling Liquified Petrole

30、um (LP) Gases (Manual Method),” ASTM Practice D 5287, “Automatic Sampling of Gaseous Fuels,” UOP Method 516, “Sampling and Handling of Gasolines, Distillate Fuels, and C3-C4 Fractions,” or other reliable technique. Preparation of Apparatus 1. Install the gas purifiers in the supply line between the

31、instrument gases and the gas chromatograph. Low detection limits are required for the analysis. Purifiers are essential for all gases used, and must be routinely replaced to be effective. Follow the vendors recommended replacement schedule. 2. Install the Silcosleeve metal inlet liner into the front

32、 injection port according to the instrument manufacturer instructions. The Silcosleeve liner has equivalent inertness to glass sleeves but, has greater total volume, allowing the large injections of LPG and volatile liquids to be contained in the injection port. 3. Follow the instrument set-up proce

33、dure provided with the manufacturer and establish the recommended operating conditions as given in Table 1. CAUTION: Hydrogen gas leakage into 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 perio

34、dically thereafter. Initially, the injection port should be conditioned for 24 hours at 250C to clean the Silcosteel injection port liner. Then, the injection port temperature should be reduced to operating temperature. Other conditions may be used provided they produce the required sensitivity and

35、chromatographic separations equivalent to those shown in the Typical Chromatograms (Figures. 2 through 4). 4. Install deactivated fused silica tubing between the front injection port, the back injection port, and the associated bulkhead fittings. 5. Install the remaining deactivated fused silica tub

36、ing in the GC oven between the bulkhead and Valve 2, Port 1, and the bulkhead and either the vent or back FID detector, if present. 6. Install the Lowox column in the GC oven. The inlet end of the column connects to a bulkhead, the outlet end of the column connects to the “front” detector. 7. Check

37、all fittings for leaks using an electronic leak detector. Do not use liquid leak detector on capillary lines. CAUTION: Hydrogen gas leakage into 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 per

38、iodically thereafter. Fractionation Time Determination 1. With the instrument operating at the established conditions, set Valve 2 to the “off” position. 2. Set up a run table on the GC with Valve 2 “on” at 3.00 minutes and Valve 2 “off” at 19.5 minutes. 3. Prepare a qualitative mixture of oxygenate

39、s in cyclohexane by the following procedure. This mixture is used to determine retention times of the oxygenates. Fill a 500-mL bottle with 450 mL of cyclohexane Add 1 mL of 1-pentanol 5 of 16 960-16 Add 5 L each of the oxygenates in Table 2, mix well Methyl ether is a compressed gas. It should be b

40、ubbled into the blend bottle by flowing it through a section of 1/16-inch tubing that is immersed in the cyclohexane, for 3 to 4 seconds. 4. Inject 4 L of the qualitative mixture and start the GC and integrator. The qualitative mixture determines retention times for all possible components and is us

41、ed to set fractionating cut times. It is not expected that samples for this analysis will contain all oxygenates found in the qualitative mixture. 5. Reduce the Valve 2 “on” time by 0.05 minute increments until the 1-pentanol peak begins to diminish in size. Record the value before the area diminish

42、ed as the cut time for Valve 2. Table 1 Recommended Operating Conditions Carrier gas hydrogen Front Inlet Temperature 250C isothermal Column head pressure 50C 26.2 kPa gauge (0.8 psig) Equivalent flow 18.6 mL/min Flow mode constant flow Pressure pulse 53.8 kPa gauge (7.8 psig) Pulse time 0.25 min Sp

43、lit ratio 1.0 Split flow 7.8 mL/min Back Inlet Temperature 120C Column head pressure 50C 5.5 kPa gauge (0.8 psig) Equivalent flow 5.0 mL/min Flow mode constant flow Split ratio 5.0 Split flow 25.1 mL/min Auxiliary 1 temperature (Wasson ECE valve box) 150C isothermal Auxiliary 2 temperature (heated c

44、hannel) 150C isothermal Main oven temperature programming Initial temperature 50C Initial time 0 min Programming rate 10C/min Final temperature 250C Final time 0 min Front Detector FID Temperature 250C Hydrogen flow rate* 25 mL/min Air flow rate* 400 mL/min Makeup nitrogen flow rate* 25 mL/min Const

45、ant makeup mode Back Detector (if installed) FID Temperature 250C Hydrogen flow rate* 30 mL/min Air flow rate* 400 mL/min Makeup nitrogen flow rate* 25 mL/min Constant makeup mode 6 of 16 960-16 Run Table Valve 2 “on” at 2.75 min Valve 2 “off” at 19.5 min For LPG samples add: Valve 1 “on” at 0.01 mi

46、n Valve 1 “off” at 0.6 min For Gas samples add: Valve 3 “on” at 0.01 min Valve 3 “off” at 19.0 min Sample size Liquids 4.0 L (syringe) LPG 2.0 L (valve) *Consult the manufacturers instrument manual for suggested flow rates Calibration Blends - Liquid Samples Prepare a calibration blend as described

47、in ASTM Method D4307, “Preparation of Liquid Blends for Use as Analytical Standards,” to contain approximately 50 mass-ppm of 2-butanone in cyclohexane. Run the calibration blend in triplicate daily when samples are analyzed as described under Chromatographic Technique. The lifetime of this calibrat

48、ion blend is estimated at one week. Peak areas from each of the triplicate runs should not deviate from the average by more than 5% of the value. If greater deviations occur, make certain that there are no problems with the equipment, then make additional runs until the required repeatability is obt

49、ained on three consecutive runs. Calibration Blends - Gas samples A blend containing approximately 100 mol-ppm of dimethyl ether in high-purity propane is required for calibration. Run the calibration blend in triplicate daily when samples are analyzed as described under Chromatographic Technique. Peak areas from each of the triplicate runs should not deviate from the average by more than 5% of the value. If greater deviations occur, make certain that there are no probl