UOP 912-2006 Fluoride in Catalysts Molecular Sieves and Aqueous Solutions by Ion Selective Electrode.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 1991, 1994, 2006 UOP LLC. All rights r

3、eserved. Nonconfidential 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

4、610.832.9585 PHONE. Fluoride in Catalysts, Molecular Sieves, and Aqueous Solutions by Ion Selective Electrode UOP Method 912-06 Scope This method is for determining total fluoride in aluminosilicate catalysts and molecular sieves, and inorganic fluoride in aqueous samples. The method is particularly

5、 useful for catalysts containing zirconia or other metals that interfere with alternative procedures. The range of fluoride typically determined is from 0.01 to approximately 20 mass-% for catalysts or molecular sieves, and 0.01 to approximately 50 mass-% for aqueous samples. References UOP Method 9

6、18, “Collection and Grinding of Adsorbents and Catalysts for Analysis,” www.astm.org UOP Method 954, “Loss on Ignition (LOI) for Fresh, Regenerated, Used, and Spent Catalysts, Catalyst Supports, and Adsorbents,” www.astm.org UOP Method 999, “Precision Statements in UOP Methods,” www.astm.org Outline

7、 of Method Fluoride is quantitatively separated from a solid sample by fusion with an accelerant at 1000C in a steam atmosphere. The fluoride is converted to hydrofluoric acid (HF) and is collected with the steam condensate. The condensate flows into a polypropylene beaker containing a sodium hydrox

8、ide solution. The sodium hydroxide in the solution prevents volatilization of the HF by converting it to sodium fluoride. The condensate solution is then diluted to a specific volume with water. The solution is mixed with an ionic strength activity buffer, and the fluoride concentration is measured

9、potentiometrically by comparison to standard fluoride solutions using an ion-selective electrode. Inorganic fluoride is determined in aqueous samples by dilution to a specific volume with water. The solution is mixed with an ionic strength activity buffer and the fluoride concentration is determined

10、 potentiometrically as described above. 2 of 12 912-06 Apparatus References to catalog numbers are included as a convenience to the method user. Other suppliers may be used. Aluminum press and die, for forming nickel boats and boat covers to fit in the heavy wall nickel boat, fabricate locally Balan

11、ce, readability 0.1-mg Beaker, graduated, 150-mL, polypropylene, Fisher Scientific, Cat. No. 02-591-10C Boat puller, LECO Corporation, Cat. No. 501-062 Clamps, tubing, Fisher Scientific, Cat. No. 14-198-5A, or cable ties, to secure tubing to fittings Connector, polypropylene, T-shaped, 7.9-mm OD, Fi

12、sher Scientific, Cat. No. 15-319D Crucible, porcelain, high form, 10-mL, Fisher Scientific, Cat. No. 07-965C Electrode, combination fluoride, Orion, Model 96-09, Fisher Scientific, Cat. No. 13-641-904 Flasks, volumetric, polypropylene, Class B, 100-, 250-, 500- and 1000-mL, Fisher Scientific, Cat. N

13、os. 10-198-50B, D, E and F, respectively Flask, round bottom, borosilicate glass with three vertical necks and 24/40 joints, 3-liter, Fisher Scientific, Cat. No. 10-164D Furnace, split-tube, capable of maintaining 1100C, Fisher Scientific, Cat. No. 10-559-15 Heating mantle, with controller, for 3-li

14、ter flask, Fisher Scientific, Cat. No. 11-474-105G Jack, laboratory, 200- x 200-mm, Fisher Scientific, Cat. No. 14-673-52, two required Magnetic stir bar, Fisher Scientific, Cat. No. 14-512-126 Magnetic stirrer, Fisher Scientific, Cat. No. 14-493-120S Meter, benchtop, pH/mV/ISE, Orion, Model EA 940,

15、 Fisher Scientific, Cat. No. 13-641-741 Nickel boats, heavy wall, Fisher Scientific, Cat. No. 07-645 Nickel ribbon, nickel No. 201 ASTM B 162, 0.002- x 1.00-inch, Allegheny Ludlum. Fabricate disposable boats and lids from nickel ribbon using the aluminum press and die. Pinchcock, Day, Fisher Scienti

16、fic, Cat. No. 05-867 Pipet filler, Fisher Scientific, Cat. No. 03-692-35 Pipets, volumetric, Class A, 1-, 5-, 10-, 25- and 50-mL, Fisher Scientific, Cat. Nos. 13-660A, E, F, J and K, respectively Reaction chamber-condenser assembly (nickel pyrohydrolysis tube), handle assembly, and sample port closu

17、re, (see Figures 1, 2, and 4), fabricate locally Rubber stopper, black, solid, size No. 4, Fisher Scientific, Cat. No. 14-130G, two required Rubber stopper, black, two-hole, size No. 4, Fisher Scientific, Cat. No. 14-140M Spatula, micro, Fisher Scientific, Cat. No. 21-401-15 Support ring, cork, 140-

18、mm OD, Fisher Scientific, Cat. No. 07-835B 3 of 12 912-06 Tubing, borosilicate glass, standard wall, 6-mm OD, Fisher Scientific, Cat. No. 11-362D Tubing, clear, silicone rubber, 6.4-mm ID, Fisher Scientific, Cat. No. 14-169-3C, for steam lines Tubing, laboratory, Tygon R-3603, 6.4-mm ID, Fisher Scie

19、ntific, Cat. No. 14-169-3C, for water lines Tubing clamp, flatjaw pinchcock, Fisher Scientific, Cat. No. 05-850A Reagents and Materials All reagents shall conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society, when such specifications are

20、available, unless otherwise specified. References to water mean deionized or distilled water. References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Accelerant, Com-Cat Accelerator, LECO Corporation, Cat. No. 502-321. Vanadium pento

21、xide, 99.99% purity, Aldrich Chemical, Cat. No. 20,485-4, may be substituted and provides equivalent performance. Care must be taken when handling vanadium pentoxide including the wearing of gloves because it is toxic and an irritant. Electrode filling solution, fluoride combination electrode, Fishe

22、r Scientific, Cat. No. 13-641-899 Fluoride standard, 100 g/mL, AccuStandard, Cat. No. IC-F-1X-5 Methyl purple indicator, Aldrich Chemical, Cat. No. 27,733-9 Phosphate rock, reference standard, approximately 3.82% fluorine, NIST, Cat. No. SRM 120c Pipet dropper bulbs, Fisher Scientific, Cat. No. 03-4

23、48-26 Pipets, transfer, disposable, Fisher Scientific, Cat. No. 13-711-7 Sodium hydroxide, 0.1-M, Aldrich Chemical, Cat. No. 319481 TISAB II (total ionic strength activity buffer), fluoride electrode activity standard, Fisher Scientific, Cat. No. 13-641-873 Toothpaste, non-gel type containing fluori

24、de Water, deionized or distilled Water, tap, for cooling Procedure The analyst is expected to be familiar with general laboratory practices, the technique of titration, and with the equipment being used. Preparation of Fluoride Standards Fluoride Standard, Approximately 100-g/mL F This is the reagen

25、t standard as received. Fluoride Standard, Approximately 10-g/mL F Pipet 10 mL of the 100-g/mL F standard into a 100-mL polypropylene volumetric flask and fill to the mark with water. Invert several times to mix. 4 of 12 912-06 The actual concentration of this standard will be one-tenth of the stand

26、ard being diluted. Fluoride Standard, Approximately 1-g/mL F Pipet 1 mL of the 100-g/mL F standard into a 100-mL polypropylene volumetric flask and fill to the mark with water. Invert several times to mix. The actual concentration of this standard will be one-hundredth of the standard being diluted.

27、 Control Standards Prepare larger volume control standards, at fluoride levels corresponding to typical samples, in a manner analogous to the fluoride standards. Instrument Set Up Refer to Figure 3 for assembly of the apparatus described in the following steps. 1. Place the reaction chamber-condense

28、r assembly (Figure 1) into the furnace with the handle (Figure 2) attached to the end as shown in Figure 3 and close the furnace. Insert the sample port closure (Figure 4) into the inlet of the reaction chamber. 2. Connect one leg of the sample port closure to the tap water supply using laboratory t

29、ubing. Water is used as a coolant to keep the rubber port closure at low temperature to prevent thermal decomposition. Secure this and all tubing connections with tubing clamps or cable ties to prevent unintended separation. 3. Connect the other leg of the sample port closure to the inlet tube of th

30、e condenser using laboratory tubing. 4. Connect the laboratory tubing to the outlet tube of the condenser and direct the exit to drain. 5. Attach a short length of laboratory tubing to the condenser exit for the collection of condensate. 6. Place the round bottom flask in the flask heating mantle. 7

31、. Insert a 60-cm length of glass tubing through a two-hole rubber stopper so that the end almost touches the bottom of the flask. This tubing is to relieve pressure build-up in the flask. 8. Insert a short length of glass tubing through the second hole of the rubber stopper and insert this stopper i

32、nto the center opening of the flask. This is the steam generator outlet. 9. Place a solid rubber stopper into the other two openings of the flask. These openings are used to add water to the flask. 10. Connect the steam generator outlet to a T-shaped connector with laboratory tubing. 11. Connect one

33、 of the exits of the T-shaped connector to the copper tube on the inlet of the reaction chamber using a section of laboratory tubing. Connect a length of laboratory tubing to the third exit that leads to a drain. The steam flow to either position is controlled by a pinchcock. 5 of 12 912-06 Sample P

34、reparation Catalyst Samples (non-hygroscopic) Volatile-free Basis If catalyst samples are to be reported on a volatile-free basis, determine the volatiles in the samples using the following procedure. 1. Obtain approximately 5 g of the ground catalyst sample according to UOP Method 918. 2. At the sa

35、me time that the analytical sample is weighed, weigh, in duplicate, approximately 2-g samples and determine the LOI at 900C by UOP Method 954. Other temperatures may be used, so long as the data is reported as volatile free at the specific temperature used. Catalyst Samples (non-hygroscopic) Prepare

36、 catalyst samples for titration as follows: 1. Fill the round-bottom flask approximately 3/4 full with water. Turn on the tap cooling water to the sample port closure/condenser. Turn on the heating mantle and adjust it to produce a slow constant boiling of the water (approximately 4 to 5 mL/min). Tu

37、rn on the tube furnace and raise the temperature to the setpoint of 1000C. Open the pinchcock on the tubing to the drain and close the pinchcock to the reaction chamber. Follow the manufacturers instructions for operation of the furnace. Turn off the furnace and steam generator when not in use. Turn

38、 off the cooling water after the furnace has cooled to ambient temperature. 2. Run blanks in duplicate as described in Steps 3 through 13 but omit the sample. The first blank is used to condition the reactor and is to be discarded. The second blank is used to determine the F, mass-% as shown under C

39、alculations. 3. Weigh approximately 2 g of the accelerant into the bottom of the disposable nickel boat, and tare. 4. Weigh the portion of the sample to be used for the fluoride analysis, to the nearest 0.1 mg, into the disposable boat and mix well with accelerant using the spatula. The sample shoul

40、d be collected and prepared according to UOP Method 918. The sample amount depends on the concentration of fluoride present. Use Table 1 as a guide to choose the appropriate sample mass. Take care that no sample remains clinging to the spatula after mixing. Table 1 Mass of Sample to be Used Estimate

41、d Fluoride, mass-% Approximate Sample Mass, g 0.01 to 1 1 to 10 10 to 20 0.3 0.1 0.05 5. Place the disposable nickel boat inside the heavy wall nickel boat, cover with the nickel lid. 6 of 12 912-06 6. Place a 150-mL polypropylene beaker containing approximately 5 mL of 0.1-M NaOH and 4 drops of met

42、hyl purple indicator under the condenser so that the tubing on the outlet of the condenser tube is immersed into the solution. 7. Verify the generation of steam by observing the production of condensate at the outlet to drain, and drain the condensate. 8. Remove the inlet port closure and push the c

43、overed nickel boat into the reactor using the boat puller. Position the boat so that the rear (flat end) of the boat is at the mid-point of the hottest zone in the reactor. For this procedure, the hottest zone is identified as the mid-point of the furnace. 9. Close the reactor as soon as possible af

44、ter positioning the boat and immediately begin the introduction of steam by opening the pinchcock on the tubing connected to the reaction chamber and closing the pinchcock on the tubing connected to the drain. 10. Collect approximately 60 mL of condensate (nominally about 15 minutes) in the 150-mL p

45、olypropylene beaker. Periodically add 0.1-M NaOH dropwise to maintain the solution basic as indicated by a green color. The solution is maintained basic to prevent hydrofluoric acid from volatilizing. 11. Remove the beaker so that the condenser tip is no longer submerged and set the beaker aside. Th

46、e passage of steam is continued for 5 more minutes to flush out the reactor. Collect the condensate from the flushing in a separate beaker. The condensate from the flushing is discarded. Additional flushing time is required after a sample of high fluoride content is analyzed. 12. Open the pinchcock

47、to the drain and close the pinchcock to the reaction chamber. Remove the nickel boats from the reaction chamber with the boat puller and discard the inner disposable boat, its contents, and the lid in a safe manner. 13. Transfer the condensate solution in the 150-mL beaker quantitatively to a 250-mL

48、 volumetric flask and dilute to volume with water. Cap and mix well by inverting several times. The analysis of the solution must be performed on the same day as the pyrohydrolysis. Molecular Sieve Samples (hygroscopic) Prepare molecular sieve samples for titration as follows. 1. Obtain approximatel

49、y 5 g of the sample according to UOP Method 918. 2. Spread the ground sample in a thin layer on a non-porous, non-contaminating surface. The sample is covered with an acceptable media such as a paper towel to prevent foreign matter from falling on it and to provide ventilation access from all sides. 3. Expose the spread sample for at least four hours in the laboratory where weighing is to be performed. 4. Analyze the sample as described in Steps 1 through 13 under Catalyst Samples. 5. At the same time that the analytical sample is weighed