UOP 1014-2017 Determination of Trace Propadiene and Methyl Acetylene Impurities in Polymer Grade Propylene by Gas Chromatography.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 2017 UOP LLC. All rights reserved. . Nonconfiden

3、tial UOP Methods are available from ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. 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. Determination of Trace Propadiene and Methyl Acetylene Impurities in Polymer Grade Propylene by Gas Chromatography UOP Method 1014-17 Scope This method is for determining trace methyl acetylene and propadiene (MAPD) in high purity polymer grade propylene liquid or gas using a preconfigured,

5、commercially available gas chromatograph. Other impurities of C3-C5 if present can also be determined. The range of quantitation for each component is 0.2 to 2000 mass- (or mol-) ppm. This method can be used to determine trace impurities in ethylene with appropriate gas injection valve and customize

6、d run program. For a full characterization of the C5 minus impurities to a lower limit of quantitation of 2 ppm refer to UOP 899. References UOP Method 899, “Trace Hydrocarbons in Hydrogen, Hydrocarbon Gases, or LPG by GC,” www.astm.org UOP Method 999, “Precision Statements in UOP Methods,” www.astm

7、.org Wasson ECE Instrumentation, Application 263-SP instrument manual Wasson ECE Instrumentation, Vaporizer instrument manual Outline of Method The method requires the use of a dedicated gas chromatographic system that is configured for automated analysis which is capable, via valving and a vaporize

8、r, of determining impurities in polymer-grade propylene gas or liquid. A reproducible sample volume is injected into a GC configured with a vaporizer (external or on-board), gas sampling valve, split/splitless inlet, flame ionization detector (FID), and control and quantitation software. Through the

9、 use of multiple valves, a portion of the sample is injected onto the first column where molecules are separated by boiling point. Next, a portion of the sample, mostly propylene and higher boiling analytes, is cut onto a second column where molecules are separated based on polarity and sent to the

10、FID for detection. The concentrations of methyl acetylene and propadiene (MAPD) in propylene sample matrices are determined by the external standard method of quantitation, wherein peak areas of the sample impurities are compared to peak areas of a calibration blend. 2 of 11 1014-17 Significance and

11、 Use High purity propylene and ethylene are commonly used as the feedstock for production of polypropylene, and the quality of this monomer is critical to successful polymerization. The presence of trace amounts of certain hydrocarbon impurities can have adverse effects on the product quality. This

12、test method is suitable for setting specifications, for use as an internal quality control tool, and for use in development or research work. Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Analyzer, Wasson-ECE Inst

13、rumentation Application 263-SP “Analysis of Impurities in Polymer-grade Propylene” Gas chromatographs are available pre-configured, including a data system, from several suppliers. Confirm with the supplier that the analyzer is appropriate for the stream to be analyzed and the analysis required (see

14、 Figure 1 for Analyzer configuration) which includes: Chromatographic column 1, 30 m of 0.53-mm ID fused silica capillary, internally coated to a film thickness of 0.5-m (bonded) with poly-dimethyl siloxane, boiling point column. Wasson ECE, Part No. 2337 Code KC79 Chromatographic column 2, 50 m of

15、0.53-mm ID PLOT fused silica capillary, internally coated to a Film thickness of 9-m with alumina (GS-Alumina), Wasson ECE, Part No. 2491 Code KC136 Gas chromatograph, capable of multiple temperature ramping, built for capillary column chromatography utilizing a split injection system with electroni

16、c pressure control (EPC), having a glass injection port insert and flame ionization detector. Three channels of additional electronic pressure control is required. Agilent Technologies, Model 7890. Vaporizer, model A1034-003, Wasson-ECE Instrumentation, Figure 2 shows Vaporizer flow path. Clamp, for

17、 ring stand and sample cylinders, Fisher Scientific Cat. No. 02-217-000 Clamp holder, for ring stand and clamp, Fisher Scientific Cat. No. 02-217-005 Tubing, stainless steel, 1.6-mm (1/16-inch) OD, 0.76-mm (0.030-inch) ID, Fisher Scientific, Cat. No. AT3003 Tubing, translucent, FEP Teflon, 3.2-mm (1

18、/8-inch) OD, 1.6-mm (1/16-inch) ID, 3450 kPa (500 psi), Thomas Scientific, Cat. No. 9567K20 Integrator, or data system, electronic, for obtaining 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 ac

19、curately measured. ChemStation, Agilent Technologies. Leak detector, gas, Fisher Scientific, Cat. No. 0.-251-702 Regulator, air, two-stage, high purity, delivery pressure range 30 to 700 kPa (4 to 100 psi), Matheson Tri-Gas, Model 3122-590 Regulator, helium, two-stage, high purity, delivery pressure

20、 range 30 to 700 kPa (4 to 100 psi), Matheson Tri-Gas, Model 3122-580 Regulator, hydrogen, two-stage, high purity, delivery pressure range 30 to 700 kPa (4 to 100 psi), Matheson Tri-Gas, Model 3122-350 3 of 11 1014-17 Regulator, nitrogen, two-stage, high purity, delivery pressure range 30 to 700 kPa

21、 (4 to 100 psi), Matheson Tri-Gas, Model 3122-580 Ring stand, with rectangular base, 140- x 229-mm with 610-mm rod, Fisher Scientific, Cat. No. 14-679Q Reagents and Materials References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Ca

22、libration blend, LPG, quantitative, primary Propylene standard, in a piston cylinder, pressurized with nitrogen to 800 psig, containing approximately 3 ppm of each of the following trace components: Isobutane, n-Butane, Propadiene, trans-2-Butene, 1-Butene, Isobutene, cis-2-Butene, Isopentane, Methy

23、l Acetylene, n-Pentane, 1,3-Butadiene in Propylene. Local supply. Air, zero gas, total hydrocarbons less than 2.0 ppm as methane Helium, chromatographic grade, typically 99.995% purity Nitrogen, zero gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane Hydrogen, zero-gas, 99.9

24、5% minimum purity, total hydrocarbons less than 0.5 ppm as methane Gas purifier, helium, used to remove oxygen and moisture from carrier gas, VICI Metronics, Cat. No. P100-1 Procedure The analyst is expected to be familiar with general laboratory practices, the technique of gas chromatography, and t

25、he equipment being used. Dispose of used reagent, material, and samples in an environmentally safe manner according to local regulations. Sampling Obtain the sample by following the procedures described in ASTM Practice D 1265, “Sampling Liquefied Petroleum (LP) Gases (Manual Method),” ASTM Practice

26、 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. Chromatographic Technique 1. Follow the instrument site preparation checklist provided by the manufacturer and arrange for install

27、ation by the manufacturers service engineer to establish recommended operating conditions. The Wasson-ECE analyzer comes with on-site installation and training by a Wasson-ECE engineer in the continental U.S., inquire with Wasson-ECE for other locations 2. Install the gas purifier in the supply line

28、 between the carrier gas source and the carrier gas inlets on the gas chromatograph Column life is significantly reduced if the gas purifier is not used. Replace the gas purifier at intervals determined by good laboratory practice. An indicating oxygen trap may be placed downstream of the gas purifi

29、er. When the indicator shows one-half used, replace both the gas purifier and the indicating trap. 3. Place the LPG sample cylinder in a vertical position. If the cylinder has an outage tube, the outage tube must be at the top. Briefly open the bottom valve to check that no water or sediment is pres

30、ent in the LPG. If water or sediment is determined to be present, discontinue the analysis 4 of 11 1014-17 and obtain a clean sample. LPG samples are usually contained in a cylinder having valves on both ends or, in some cases, a cylinder where one of the valves is connected to an eductor tube. If t

31、he sample cylinder contains an eductor tube, invert the cylinder (both valves on the bottom) and briefly open the valve not connected to the eductor tube to check that no water or sediment is present. See Figure 3 for diagram of common LPG cylinders. 4. Pressurize the LPG cylinder containing the sam

32、ple to approximately 1400 to 2068 kPA gauge (200 to 300 psig) with nitrogen or helium. 5. Mount the cylinder in a vertical position. If the cylinder has an outage tube, the outage tube fitting must be at the top. 6. Attach the sample cylinder to the appropriate liquid bulkhead on the front of the va

33、porize If the cylinder is fitted with an eductor tube, connect the eductor tube outlet to the sample injection inlet tubing in such a manner that the eductor tube is sampling liquid LPG. The connecting tubing between the cylinder and the vaporizer must be as short as possible. 7. Ensure that the ven

34、t purge valve is closed. 8. Ensure the vaporizer temperature is set at desired conditions and all vent and sample lines are connected. Wasson ECE vaporizer temperature is set to 180C. If using different vaporizer, refer to instrument manual. 9. Fully open the bottom valve, or eductor valve, of the s

35、ample cylinder to allow sample to pressurize the sample line. 10. Partially open the liquid purge valve (about one turn counter-clockwise). Wait until the flow emitting from liquid sample vent from the back of the vaporizer become liquid. If it does not, the pressure in the sample cylinder may be to

36、o low. 11. Continue the flow until entrained bubbles are no longer observed through the translucent tubing. CAUTION: Inspect the translucent tubing regularly. Replace at first signs of wear or kinking. Pressure rating on the translucent tubing must be rated higher than pressure on sample or blend cy

37、linder. 12. Close the liquid purge valve to block venting liquid. 13. Monitor the vent bubbler, allow about 1 minute for the vaporized sample to sweep through the gas chromatograph gas sampling valve. 14. Inject the sample by switching the injection valve to the inject position, and start the integr

38、ator and the column temperature programming sequence. 15. Close the LPG sample cylinder valve and immediately open the vent purge valve to vent the sampling system. 16. Identify each component by comparing the resultant chromatogram with the Typical Chromatogram as shown in Figure 4. Operating Condi

39、tions It is recommended to use the manufacturer operating conditions for this analysis to produce the required sensitivity and chromatographic separations equivalent to those shown in the Typical Chromatogram. 5 of 11 1014-17 Table 1 Recommended Operation Conditions Carrier gas hydrogen Column 1 hea

40、d pressure 9.0 psig Mode constant flow Equivalent flow 40C 5 mL/min flow rate Equivalent linear velocity 40C 30 cm/sec Split flow rate 100 mL/min Injection port temperature 250C Column 2 head pressure 9.0 psig Mode constant flow Equivalent flow 40C 5 mL/min flow rate Equivalent linear velocity 40C 3

41、2 cm/sec Split flow rate 100 mL/min Injection port temperature 250C Columns temperature program Initial temperature 40C Initial time 6 min Programming rate A 5C/min Intermediate temperature 90C Intermediate hold time 0 min Programming rate B 25C/min Final temperature 180C Final hold time 4.4 min Det

42、ector flame ionization Detector temperature 250C Hydrogen flow rate 40 mL/min Air flow rate 350 mL/min Makeup off Makeup flow rate 30 mL/min Sample size 1 ml repeatable *see instrument manufacturers specifications Calibration Response factors are required to relate detector response for each sample

43、component to mass-ppm. Response factors are determined by the analysis of one or more calibration blends. All blends should be analyzed in triplicate. For each impurity present in the standard, calculate the calibration factor as follows: R = AB (1) where: R = response factor B = concentration of th

44、e impurity the standard, mass-ppm A = area counts obtained for that impurity Calculations Obtain peak areas for each individual component or group of components and calculate the composition of the sample to the nearest 0.1 mass-ppm using Equation 2: 6 of 11 1014-17 Component, mass-ppm = R * H (2) w

45、here: R = absolute response factor, previously defined, Equation 1 H = peak area of individual component or group of components When mole-ppm concentrations are required, as in the case of analyzing a gas, the conversion can be made using Equation 3. Component, mol-ppm = D42.08*C (3) where: C = comp

46、onent concentration in sample, mass-ppm D = molecular weight of component, g/mole 42.08 = molecular weight of propylene, g/mole Precision Precision statements were determined on one gas and one LPG samples using UOP Method 999, “Precision Statements in UOP Methods.” Repeatability and Site Precision

47、A nested design was carried out for various trace impurities on two samples performed on a Wasson ECE Instrumentation configured GC. Two analysts carried out two tests on two separate days for components in a LPG sample for a total of 16 analyses. Using a stepwise analysis of variance procedure, the

48、 within-day and within-lab estimated standard deviations (esd) were calculated at the concentration means listed in Table 2. Two analyses performed in one laboratory by the same analyst on the same day should not differ by more than the repeatability allowable differences shown in Table 2 with 95% c

49、onfidence. Two analyses performed in one laboratory by different analysts on different days should not differ by more than the site precision allowable differences shown in Table 2 with 95% confidence. Table 2 Gas Sample Repeatability and Intermediate Precision, mass-ppm Repeatability Site Precision Component Mean Within Day esd Allowable Difference Within Lab esd Allowable Difference Propadiene 0.4 0.01 0.1 0.01 0.1 Methylacetylene 0.4 0.01 0.1 0.01 0.1 Isobutane 0.6 0.04 0.1 0.