UOP 730-2009 Total Oxygen in Liquid Hydrocarbons by Pyrolysis.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 2009 UOP LLC. All rights reserved. Non

3、confidential 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 610.832.9585

4、 PHONE. Total Oxygen in Liquid Hydrocarbons by Pyrolysis UOP Method 730-09 Scope This method is for determining total oxygen in liquid hydrocarbons, including synthetic paraffinic kerosene (SPK) and bio-derived green diesel fuel, by pyrolysis. The method is applicable to concentrations ranging from

5、approximately 0.02 to 1.0 mass-%. Higher concentrations can be determined with appropriate sample dilution. The method determines the total oxygen, including organic oxygen compounds, dissolved water, and dissolved molecular oxygen. Contributions of oxygen from water and dissolved molecular oxygen m

6、ust be measured using other methods (see References below) and subtracted from this result. References ASTM Method D 4052, “Density and Relative Density of Liquids by Digital Density Meter,” www.astm.org UOP Method 481, “Water in Liquid Hydrocarbons by Coulometry,” or ASTM Method D6304, “Water in Pe

7、troleum Products, Lubricating Oils, and Additives by Coulometric Karl Fischer Titration,” www.astm.org UOP Method 678, “Dissolved Molecular Oxygen in Liquid Hydrocarbons by Electrochemical Detection,” www.astm.org UOP Method 999, “Precision Statements in UOP Methods,” www.astm.org Outline of Method

8、An oxygen analyzer (CHN/O instrument) is set up and calibrated with liquid standards. Samples are directly injected into the pyrolysis tube in a helium carrier. Samples are pyrolyzed at a temperature in excess of 1000C. Subsequently, a metallized carbon reagent helps to quantitatively convert all of

9、 the oxygen into carbon monoxide (CO). Acid gas is removed from the product stream with an appropriate trap material (soda lime). The pyrolysis product gas is passed through a GC column to separate the CO. The CO content is measured using thermal conductivity detection. Apparatus References to catal

10、og numbers and suppliers are included as a convenience to the method user. 2 of 7 730-09 Other suppliers may be used. Balance, readability 0.1-mg CHN/O Analyzer, Model Flash EA1112, Thermo Scientific, available from CE Elantech. Instrument is equipped with a liquid autosampler. Follow the manufactur

11、ers recommendations for maintaining a supply of spare parts and consumables, such as autosampler vials. Any use of an alternative instrument must be tested to determine if it provides equivalent sensitivity and precision. Flasks, volumetric, Class A, borosilicate glass, 10-, 25-, and 50-mL, Fisher S

12、cientific, Cat. Nos. 20-812D, 10-210-8A, -8B, respectively Pipet, transfer, disposable plastic, 152-mm length, Fisher Scientific, Cat. No. 13-711-SA Pipet, volumetric, Class A, 1-, 2-, 5- and 10-mL, Fisher Scientific, Cat. No. 13-650-2B, -2C, -2F, and -2L, respectively Pipet filler, Fisher Scientifi

13、c, Cat. No. 13-681-51 Regulator, helium, two-stage, high purity, with stainless steel diaphragm, delivery pressure range 30-700 kPa (4-100 psi), Matheson, Cat. No. 3810-580 Syringe, gastight, 250-L, CE Elantech, Cat. No. 365-040-42 Reagents and Materials References to catalog numbers and suppliers a

14、re included as a convenience to the method user. Other suppliers may be used. References to water mean deionized or distilled water. The following items are required to perform the analysis. Additional reagents and materials may be required depending on the specific oxygen analyzer utilized. Where d

15、ifferent reagents are specified in the instrument manual, follow the manufacturers recommendations. Benzoic Acid, Aldrich, Cat. No. 242381-100G Helium, compressed gas, 99.999% minimum purity, such as Matheson Ultra High Purity. Magnesium perchlorate (Anhydrone), Thermo Electron, Cat. No. 338-219-00

16、Nickel coated carbon, Thermo Electron, Cat. No. 338-238-00 Quartz turnings, Thermo Electron, Cat. No. 338-223-10 Quartz wool, Thermo Electron, Cat. No. 338-222-50 Soda lime, Thermo Electron, Cat. No. 338-352-30 Toluene, anhydrous, Burdick 3 or 4 injections are recommended. Average the results. The r

17、epeatability of the replicates should be within the precision of the method. If they are not, look for air bubbles in the syringe or other instrument malfunction. The sample must be completely injected into the pyrolysis tube. Small volumes and/or slow injection rates can result in a loss of sample

18、to the walls of the pyrolysis tube, resulting in a bias to lower results. 1 or 2 conditioning blanks should be injected before the first sample, if the instrument has been idle for longer than 30 minutes. 5. A QC sample should be analyzed before and after the set of samples to check instrument stabi

19、lity. A benzoic acid in toluene solution made at a concentration not used for calibration can be used as a QC. This solution should be prepared each week. Dilution Required for Samples Containing Greater Than 1% Oxygen 1. Calibrate the instrument using 1% oxygen standard as the highest point on the

20、calibration line. 2. Using a volumetric pipet, add 1.00 mL of sample to a 10- or 25-mL volumetric flask. 3. Dilute the sample to the mark with anhydrous toluene and shake the flask well to mix. 4. Fill an autosampler bottle with diluted sample using a disposable transfer pipet. 5. Continue with Step

21、s 3 through 5 under Sample Analysis, Dilution Not Required. Calculations The instrument software will calculate the sample results as mass/volume-% oxygen. This is calculated on a volume basis (since the injection volume remains constant) unless the sample mass is entered into the sample table. Some

22、 instruments will allow the user to enter the sample density to convert the results to mass-% oxygen. In that case, use 0.87 as the density of the toluene standards. The density of samples can be determined by other methods (see Note 2). If the instrument software does 6 of 7 730-09 not correct for

23、density, the results can be converted to mass-% oxygen by dividing the result by the sample density using Equation 2: Oxygen, mass-% =dC(2) where: C = concentration of oxygen measured, mass/volume-% d = density of the original sample, g/mL Report results for undiluted samples, ( 1% oxygen) to two de

24、cimal places. For samples that did require dilution, calculate the oxygen concentration of the original sample in mass-% using Equation 3: Oxygen, mass-% = ABdC(3) where: A = volume of sample diluted, mL (1.0 mL, from Sample Analysis, Dilution Required, Step 2) B = total volume of first dilution, mL

25、 (10 or 25 mL, from Sample Analysis, Dilution Required, Steps 2 and 3) C, d = previously defined in Equation 2 Report diluted samples to one decimal place after calculation. Notes 1. Benzoic acid solutions in toluene will reach a solubility limit at 10% benzoic acid (approximately 2.6% O). All benzo

26、ic acid/toluene solutions at or above 1% oxygen should be checked for precipitate formation before use. 2. If the density of the sample is unknown, it can be determined by ASTM D 4052, “Density and Relative Density of Liquids by Digital Density Meter,” or another acceptable density method. Precision

27、 The precision data listed below was generated using a Thermo Flash EA1112 CHN/O Analyzer. If another instrument is to be used, confirm its precision and accuracy at the oxygen concentrations to be measured. Precision statements were determined using UOP Method 999. Repeatability and Site Precision

28、A nested design was carried out for determining the oxygen content of two samples with two analysts in one laboratory. Each analyst carried out tests on two separate days, performing four tests on each sample each day. The total number of tests was 32. The precision data are summarized in Table 2. T

29、wo tests performed by the same analyst on the same day should not differ by more than the repeatability allowable difference with 95% confidence. Two tests performed in one laboratory by different analysts on different days should not differ by more than the site precision allowable difference with

30、95% confidence. The data in Table 2 are a short-term estimate of repeatability. When the test is run routinely, a control standard and chart should be used to develop a better estimate of the long-term repeatability. Reproducibility There is insufficient data to calculate reproducibility of the test

31、 at this time. 7 of 7 730-09 Table 2 Repeatability and Site Precision, oxygen, mass-% Repeatability Site Precision Sample Mean Within- Day esd Allowable Difference Within- Lab esd Allowable Difference 1 2 0.013 0.045 0.0005 0.0009 0.002 0.003 0.0012 0.0019 0.004 0.009 Time for Analysis The elapsed t

32、ime for one analysis, including calibration is approximately 1.5 hours. Each succeeding analysis requires 0.3 hour. Preparation of the calibration standards requires approximately 0.5 hour of labor. Analysis of each standard or sample requires 0.1-0.2 hour of labor (transferring or diluting samples,

33、 creating the sample table, reviewing the chromatograms, and recalculating when necessary). Suggested Suppliers Aldrich, 1000 West Saint Paul Avenue, Milwaukee, WI 53233 (414-273-3850) www.sigma- Burdick & Jackson, 1953 S. Harvey St., Muskegon MI 49442 (231-726-3171) CE Elantech, 170 Oberlin Avenue

34、 North, Suite 5, Lakewood, NJ 08701-4548 (732-370-5559) Fisher Scientific, 711 Forbes Ave., Pittsburgh, PA 15219-4785 (412-490-8300) Matheson Tri-Gas, 166 Keystone Drive, Montgomeryville, PA 18936 (215-641-2700) Thermo Electron North America LLC, 5225 Verona Road, Madison, WI 53711-4495 (608-276-6100)