UOP 983-2004 ACETYLENES IN 1 3-BUTADIENE 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 2004 UOP LLC ALL RIGHTS RESERVED uop,

3、UOP, and KLP are trademarks and/or service marks of UOP LLC. Marks of other proprietors may appear incidentally in this method for purposes such as product or service identification, but no claim is made to any other proprietors mark used. UOP Methods are available through ASTM International, 100 Ba

4、rr Harbor Drive, PO Box C700, West Conshohocken, PA 194428-2959, United States. The 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 PHONE. ACETYLENES IN 1,3-BUTADIENE BY GC uop Method 983-04 SCOPE

5、 This method is for determining low percent levels of acetylenes in crude butadiene feedstock and product, and is specifically applicable to KLP process streams. The following components and group classifications may be reported: methane, ethane, ethylene, propane, cyclopropane, propylene, isobutane

6、, acetylene, n-butane, propadiene, trans-2-butene, 1-butene, isobutylene, cis-2-butene, isopentane, n-pentane, 1,2-butadiene, methyl acetylene, 1,3-butadiene, 3-methyl-1-butene, trans-2-pentene, 2-methyl-1-butene, vinyl acetylene, ethyl acetylene, 2-methyl-2-butene, and total heavies. Components tha

7、t do not elute from the chromatographic system under the specified conditions are not determined. The range of quantitation for any compound is 0.01 to 99.9 mass-%. The analysis is applicable to laboratory or on-line use. REFERENCES ASTM Practice D 1265, “Sampling Liquefied Petroleum (LP) Gases (Man

8、ual Method),” www.astm.org Scanlon, J. T. and Willis, D. E., Journal of Chromatographic Science, 23, 333-340 (1985) UOP Method 516, “Sampling and Handling of Gasolines, Distillate Fuels, and C3-C4Fractions,” www.astm.org UOP Method 999, “Precision Statements in UOP Methods,” www.astm.org OUTLINE OF

9、METHOD The sample to be analyzed is injected as a liquefied petroleum gas (LPG) into a gas chromatograph equipped with an alumina PLOT (porous layer open tubular) capillary column, a capillary injection port, a flame ionization detector (FID), an LPG sampling valve, and a backflush valve. The PLOT c

10、olumn elutes individually measured components through 2-methyl-2-butene, after which the remainder of the sample is back-flushed to elute any remaining heavy materials. The composition of 2 of 9 983-04 the sample is obtained by the normalization technique, wherein the peak areas of the entire sample

11、 are first corrected for differences in response and then normalized to 100%. Because of the toxicity of 1,3-butadiene, follow safe venting and environmental practices. APPARATUS References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used

12、 if equivalent performance can be obtained. Fittings and connectors are listed to connect to the specified apparatus. Additional fittings will be required for the specific sample cylinders, for instrument gases, for on-line connections, and to conform to good laboratory procedures and local safety r

13、egulations. Chromatographic column, 50 m of 0.32-mm ID fused silica capillary, internally coated to a film thickness of 5-m with potassium chloride washed aluminum oxide (Al2O3/KCl), Chrompack Cat. No. 7515, Varian Inc. Fittings, bulkhead, 1.6-mm (1/16-inch) zero dead volume union with internal bore

14、 of 0.25 mm used as connection between fused silica and stainless steel tubing. Valco Instruments, Cat. No. ZBU1C. See Figure 1. Gas chromatograph, temperature programmable, capable of constant flow, built for capillary column chromatography, utilizing a split injection system, having a glass inject

15、ion port insert, a heated valve box with valve actuators, and equipped with an FID that will give a minimum peak height response of five times the background noise for 0.01 mass-% of 1-butene when operated at the recommended conditions, Agilent Technologies, Model 6890 Injection apparatus, LPG, for

16、injection of LPG samples in the liquid phase. See Figure 1. Fitting, internal union, for connecting injection port to 4-port sampling valve, Valco Instruments, Cat. No. ZU1T Fitting, reducing union, 3.2-mm (1/8-inch) to 1.6-mm (1/16-inch), Swagelok, Cat. No. SS-200-6-1 Tubing, stainless steel, for c

17、onnecting the sample cylinder to the 4-port sampling valve, 1.6-mm (1/16-inch) OD, 0.76-mm (0.30-inch) ID, Alltech Associates, Cat. No. 300010 Tubing, translucent, for connecting the 4-port sampling valve to the vent shut-off valve, FEP Teflon, 3.2-mm (1/8-inch) OD, 1.6-mm (0.062-inch) ID, 3450 kPa

18、(500 psig), Alltech Associates, Cat. No. 45740 Valve, sample injection, 4-port, stainless steel, 0.5-L internal sample volume, 1.6-mm (1/16-inch) fittings, Valco Instruments, Cat. No. CI4UWE.5, with air actuator, Valco Instruments, Cat. No. A-904, controlled by GC Valve, vent shut-off, Swagelok, Cat

19、. No. SS-ORS2 Integrator, or data system, electronic, for obtaining peak areas. This device must integrate areas at a sufficiently fast rate so that narrow peaks typically obtained from a capillary column can be accurately measured. The integrator must have programmable parameters for controlling ba

20、seline events, and have graphic capabilities. ChemStation, Agilent Technologies 3 of 9 983-04 Leak detector, gas, Alltech Associates, Cat. No. 21-250 Regulator, air, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-590, two required Regulator, heli

21、um, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Regulator, hydrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-350 Regulator, nitrogen, two-stage, high purity, delivery pressure ra

22、nge 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Tubing, fused silica, 5-m x 0.32-mm ID or smaller, deactivated fused silica tubing. If deactivated tubing is not available, a thin film poly-dimethyl siloxane column may be substituted. Tubing, stainless steel, 6-m (20-ft) x 1.6-mm (1/16-i

23、nch) OD, with internal diameter 0.5-mm (0.02-inch) or smaller, used as connection between bulkhead unions and backflush valve, and between GC and remote injection valve. Valve, backflush, Valco Instruments, Cat. No. C4UWE REAGENTS AND MATERIALS References to catalog numbers and suppliers are include

24、d as a convenience to the method user. Other suppliers may be used. Air, for valve actuation Air, zero gas, total hydrocarbons less than 2.0 ppm as methane Gas purifier, helium, Mat/Sen, Cat. No. P100-1 Helium, zero gas, total hydrocarbons less than 0.5 ppm as methane Hydrogen, zero gas, 99.95% mini

25、mum purity, total hydrocarbons less than 0.5 ppm as methane Nitrogen, zero gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane PROCEDURE Sampling Obtain the sample by following the procedures described in ASTM Practice D 1265, “Sampling Liquified Petroleum (LP) Gases (Manual

26、Method),” UOP Method 516, “Sampling and Handling of Gasolines, Distillate Fuels, and C3-C4Fractions,” or other reliable technique. 4 of 9 983-04 Instrument Set-up For health and safety reasons, set up the GC so that the sample vent, split vent and septum purge streams are vented out of the lab, or i

27、nto a hood or other well ventilated area. The backflush valve is mounted in the valve box. The LPG sample injection valve must not be heated, and should be mounted on the GC, but away from heat sources. A bracket holding the valve near but not touching the injection port is best. If safety practices

28、 demand, the LPG injection valve may be mounted up to 2 m from the GC, with only a small degradation in peak shape. For on-line applications, connect the sample stream to the sample valve as shown in the process flow diagrams. Chromatographic Technique The analyst is expected to be familiar with the

29、 technique of gas chromatography and the equipment being used. 1. Install 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 4-port LPG sampling va

30、lve external to the GC near the split injection system. Connect the related apparatus as shown in Figure 1. 5 of 9 983-04 3. Establish the recommended operating conditions as given in Table 1. Table 1 Recommended Operating Conditions Carrier gas helium Column head pressure 80C, constant flow mode 16

31、0 kPa (23.2 psig) Equivalent flow 10 mL/min Equivalent linear velocity 43.5 cm/sec Split flow rate 290 mL/min Injection port temperature 225C Valve box temperature 100C Electronic pressure control constant flow on Column temperature program Initial temperature 35C Initial time 3.1 min Programming ra

32、te A 4C/min Intermediate temperature A 125C Intermediate time A 0 min Programming rate B 8C/min Intermediate temperature B 169C Intermediate time B 0 min Programming rate C 20C/min Final temperature 200C Final time 36 min Detector FID Detector temperature 250C Hydrogen flow rate* 30 mL/min Air flow

33、rate* 400 mL/min Makeup gas nitrogen Makeup gas flow rate* 30 mL/min Sample size 0.5L *Consult the manufacturers instrument manual for suggested flow rates. 4. Condition the column according to the manufacturers instructions. 5. Cool the column oven to a stabilized 35C. 6. Place the LPG sample cylin

34、der in a vertical position in a hood or well-vented area. 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 present in the LPG. If water or sediment is determined to be present, discontinue the analysis and obt

35、ain 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 the sample cylinder contains an eductor tube, invert the cylinder (both valves on the bottom) and briefly open the

36、valve not connected to the eductor tube to check that no water or sediment is present. 6 of 9 983-04 7. Pressurize the LPG cylinder containing the sample to approximately 1400- to 2000-kPa gauge (200- to 300-psig) with nitrogen or helium. 8. Mount the cylinder in a vertical position. If the cylinder

37、 has an outage tube, the outage tube must be at the top. Connect the bottom valve to the sample injector valve inlet tubing. 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

38、LPG. The connecting tubing between the cylinder and the injector valve must be as short as possible. 9. Place the injection valve in the fill position. 10. Ensure that the vent shut-off valve is closed. 11. Fully open the bottom valve, or eductor valve, of the sample cylinder. 12. Partially open the

39、 vent shut-off valve to permit LPG flow through the sampling system. 13. Continue the flow until no entrained bubbles are observed through the translucent tubing. CAUTION: Inspect the translucent tubing regularly. Replace at first signs of wear or kinking. Pressure on the translucent tubing must nev

40、er exceed 2000 kPa (300 psig). 14. Stop the sample flow by closing the vent shut-off valve. 15. Inject the sample immediately by switching the injection valve to the inject position, and start the integrator and the column temperature programming sequence. The injection valve remains in the inject p

41、osition for the duration of the sample run. 16. Close the LPG cylinder valve and immediately open the vent shut-off valve to vent the sampling system. 17. Backflush the GC column immediately after the elution of 2-methyl-2-butene (approximately 23 minutes for the conditions listed). If no 2-methyl-2

42、-butene is present in the sample, follow the pattern of the peaks shown in Figure 2, and backflush at the appropriate time. 18. Identify the components of interest by comparing the chromatogram obtained to the Typical Chromatogram (Figure 2) and Table 2. If there is a question about the identificati

43、on of any peak, prepare or purchase a qualitative blend containing the components of interest, analyze it, and compare its chromatogram to the sample chromatogram. Calibration Since it may be difficult to purchase and maintain a calibration blend that contains all components of interest, calculated

44、response factors are used. These were calculated using the effective carbon number (ECN) concept as described by Scanlon and Willis, and are listed in Table 2. 7 of 9 983-04 Table 2 Retention Order of Identified Components and Calculated Mass Response Factors Relative to 1,3-Butadiene Peak No. Compo

45、nent Response Factor 1 Methane 1.12 2 Ethane 1.05 3 Ethylene 1.11 4 Propane 1.03 5 Cyclopropane 0.99 6 Propylene 1.02 7 Isobutane 1.02 8 Acetylene 0.71 9 n-Butane 1.02 10 Propadiene 0.99 11 trans-2-Butene 1.01 12 1-Butene 1.01 13 Isobutylene 1.01 14 cis-2-Butene 1.01 15 Isopentane 1.01 16 n-Pentane

46、1.01 17 1,2-Butadiene 1.00 18 Methyl acetylene 0.78 19 1,3-Butadiene 1.00 20 3-Methyl-1-butene 1.00 21 trans-2-Pentene 1.00 22 2-Methyl-1-butene 1.00 23 Vinyl acetylene 0.81 24 Ethyl acetylene 0.83 25 2-Methyl-2-butene 1.00 26 Heavies 0.99 CALCULATIONS Obtain the peak area for each individual compon

47、ent or group of components and calculate the concentration of each to the nearest 0.01 mass-%, using Equation 1. Component, mass-% =TPF100 )1( where: F = relative response factor, from Table 2 P = area of individual component or group of components T = the sum of the products, PF, of all the recorde

48、d components or groups of components 100 = factor to convert to mass-% 8 of 9 983-04 PRECISION Precision statements were determined using UOP Method 999. Repeatability and Intermediate Precision The same feed sample was injected into an on-line GC a total of 16 times on four separate days over a per

49、iod of 2 weeks. The precision data are summarized in Table 3. Two tests performed on the same instrument on the same day should not differ by more than the repeatability allowable difference with 95% confidence. Two tests performed by the same instrument on different days should not differ by more than the intermediate precision allowable difference with 95% confidence. Reproducibility There is insufficient data to calculate reproducibility of the test at this time. Table 3 Repeatability and Intermediate Precision, mass-% Repeatability Intermediate