UOP 961-2012 Elemental Composition of Zeolites by ICP-OES.pdf

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4、2.9585 PHONE. Elemental Composition of Zeolites by ICP-OES UOP Method 961-12 Scope This method is for the determination of components in zeolites by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), following either a digestion or a fusion preparation. Ordinarily, the metals determ

5、ined include aluminum (Al), calcium (Ca), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), gallium (Ga), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), sodium (Na), nickel (Ni), phosphorus (P), antimony (Sb), silicon (Si), tin (Sn), strontium (Sr), titanium (Ti), va

6、nadium (V), zinc (Zn), and zirconium (Zr). Barium (Ba) and lead (Pb) cannot be determined in the digest due to the formation of insoluble sulfates. Barium can be determined from the fusion solution with a quantitation limit of approximately 0.01 mass-%. This method is suitable for samples containing

7、 less than 40 mass-% alumina (Al2O3) and less than 65 mass-% silica (SiO2); however, it can be readily expanded to samples with other silica/alumina ratios utilizing the same approach as described herein. Zirconium (Zr) at levels above about one mass-% can interfere with the analysis for aluminum wh

8、en using some instruments, unless an alternative wavelength is used. Precision is about 1 to 2% relative standard deviation for elements present at concentrations greater than 0.1 mass-%. Mass balances between 98.5 and 101.5 mass-% are reported on a volatile-free basis. Precision below 0.1 mass-% do

9、es not exceed 10% relative down to the quantitation limits listed in Table 1. References 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 Out

10、line of Method The elements of interest are determined utilizing two dissolution techniques. For Si and Al, a portion of the zeolite sample is fused with lithium tetraborate and the resulting melt is dissolved in 5% hydrochloric acid. The resulting solution is analyzed by ICP and the concentrations

11、of Si and Al are determined by comparison to a NIST standard prepared in the same manner as the samples. The other components are determined following a digestion with sulfuric and hydrofluoric acids. The resulting solution is analyzed by ICP and the concentrations of metals are determined by compar

12、ison 2 of 12 961-12 to a standard solution of similar elemental and sulfuric acid concentrations. Results are reported on a volatile-free basis, with the loss on ignition (LOI) determined at 900C by UOP Method 954, “Loss on Ignition (LOI) for Fresh, Regenerated, Used, and Spent Catalysts, Catalyst S

13、upports, and Adsorbents.” Table 1 Lower Quantitation Limits for Elements Quantitation limits, Approximate mass-% Element g/mL in solution in solid as element Al 0.2 0.008 Ca 0.1 0.004 Co 0.1 0.004 Cr 0.1 0.004 Cu 0.1 0.004 Fe 0.1 0.004 Ga 0.2 0.008 K 0.2 0.008 Li 0.2 0.008 Mg 0.1 0.004 Mn 0.1 0.004

14、Mo 0.2 0.008 Na 0.2 0.008 Ni 0.1 0.004 P 0.4 0.016 Sb 0.2 0.008 Si 0.4 0.016 Sn 0.2 0.008 Sr 1.0 0.040 Ti 0.1 0.004 V 0.1 0.004 Zn 0.1 0.004 Zr 0.1 0.004 Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Balance, read

15、able to 0.0001 g Balance, top-loading, readable to 0.01 g Beaker, quartz, 250-mL, Ace Glass, Cat. No. 5334-14 Beaker, PTFE, 100- and 250-mL, Fisher Scientific, Cat. Nos. 02-586-1G and -1H, respectively Bottles, 500-mL, wide mouth, FEP, Fisher Scientific, Cat. No. 02-924-15E, several required Bottle,

16、 washing, one-liter, polypropylene, Fisher Scientific, Cat. No. 03-409-14C Burner, blast, VWR Scientific, Cat. No. 89038-548 Crucible, high form, platinum, 25-mL, Cole Parmer, Cat. No. EW-17830-45 Cylinder, graduated, polypropylene, 10-mL, Fisher Scientific, Cat. No. 03-007-38 3 of 12 961-12 Cylinde

17、rs, graduated, 50- and 100-mL, Fisher Scientific, Cat. Nos. 08-552-4B and -4C, respectively Flasks, volumetric, Class A, 500- and 2000-mL, Fisher Scientific, Cat. Nos. 10-210F, and -210H, respectively, several of each required Flasks, volumetric, 100- and 500-mL, PMP, Fisher Scientific, Cat. Nos. 10

18、-198-52C and -52F, respectively Flasks, volumetric, 100-mL, polypropylene, Fisher Scientific, Cat. No. 10-198-50B Funnel, 55-mm diameter, Fisher Scientific, Cat. No. 10-371H Fluxer, Claisse (optional), with necessary crucibles and other equipment, Claisse, Model Fluxy-30; replacement crucible, Cat.

19、No. P-130-00 Hot plate, stirring, variable heat, Fisher Scientific, Cat. No. 11-300-49SHP Hot plate, variable heat, Corning Model PC-600, Fisher Scientific, Cat. No. 11-100-49H Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), Perkin-Elmer Optima 8300DV Mortar and pestle, agate, Fi

20、sher Scientific, Cat. No.12-950B Muffle furnace (optional), capable of 1000C. The interior surface of the furnace must be of non-flaking material or sample contamination may result. Oven, drying, capable of 105C Pipets, total volume, Class A, 5-, 10-, 15-, 20-, and 25-mL, Fisher Scientific, Cat. Nos

21、. 13-650-2F, -2L, -2M, -2N, and -2P, respectively, several of each required Regulator, nitrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Stir bar, magnetic, PTFE coated, 3 x 13-mm, Fisher Scientific, Cat. No. 14-513-57 Tongs, crucible,

22、 stainless steel, lock joint, platinum shoes, Fisher Scientific, Cat. No. 15-205 Triangle, nickel-chromium, 2-inch (51-mm), Fisher Scientific, Cat. No. 15-260B Vacuum Desiccator, Corning No. 3118-160, Fisher Scientific, Cat. No. 08-632 Watch glass, borosilicate glass, 90-mm diameter, Fisher Scientif

23、ic, Cat. No. 02-612C Watch glass, PTFE, 100-mm, Fisher Scientific, Cat. No. 02-610-5E Reagents and Materials References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. References to water mean deionized water. Argon, 99.995% minimum pur

24、ity, plasma and nebulizer gas Gloves, nitrile, Fisher Scientific, Cat. No. 11-393-64A through -64E, corresponding to hand sizes 7 through 11 Hydrochloric acid, concentrated, trace metal grade, Fisher Scientific, Cat. No. A508SK212 4 of 12 961-12 Hydrochloric acid, 5% (vol/vol). Fill a 2000-mL flask

25、approximately full with water. Add 100 mL of concentrated hydrochloric acid and dilute to the mark with water. Hydrofluoric acid, concentrated, trace metal grade, Fisher Scientific, Cat. No. A513-500 Lithium tetraborate, Ultra Pure, SPEX CertiPrep, Cat. No. FF-0601 Nitric acid, concentrated Nitrogen

26、, 99.99% minimum purity, water and oil free, ICP optics purge gas Scandium oxide, 99.998% (metals basis), VWR, Cat. No. 10916 Scandium solution, 500-g/mL. Weigh 1.534 0.001 g into a 250-mL quartz beaker, rinse inside walls with water, and add an additional 20 mL of water. Add 50 mL of concentrated h

27、ydrochloric acid. Cover with a watch glass, and place on a hot plate set at 200C until dissolved. Cool and quantitatively transfer with water into a 2000-mL volumetric flask. Bring to volume with water. Store in four 500-mL FEP plastic bottles. Scandium solution, 100-g/mL. Pipet 100 mL of the 500-g/

28、mL scandium solution into a 500-mL volumetric flask. Bring to volume with water. Soda feldspar, National Institute of Standards and Technology (NIST), Cat. No. 99b Standard solutions of metals, see Table 2, SPEX CertiPrep Water, deionized Table 2 Metal Concentration, g/mL Cat. No. Metal Concentratio

29、n, g/mL Cat. No. Al 10,000 PLAL1-3X Mo 10,000 PLMO9-3X Ca 10,000 PLCA1-3X Na 10,000 PLNA1-3X Co 10,000 PLCO2-3X Ni 10,000 PLNI2-3X Cr 10,000 PLCR1-3X P 10,000 PLP9-3X Cu 10,000 PLCU1-3X Sb 1,000 PLSB5-2X Fe 10,000 PLFE1-3X Sn 1,000 PLSN5-2X Ga 1,000 PLGA2-2X Sr 1,000 PLSR2-2X K 10,000 PLK1-3X Ti 10,

30、000 PLTI5-3X Li 1,000 PLLI2-2X V 10,000 PLV3-3X Mg 10,000 PLMG1-3X Zn 10,000 PLZN2-3X Mn 10,000 PLMN2-3X Zr 10,000 PLZR3-3X Procedure The analyst is expected to be familiar with general laboratory practices, the technique of ICP-OES, and the equipment being used. Dispose of used reagents, materials,

31、 and samples in an environmentally safe manner according to local regulations. CAUTION: All subsequent steps involving lithium tetraborate fusion and handling of concentrated acids must be performed in a properly operating fume hood, and appropriate personal protection equipment must be worn (see th

32、e MSDS for each material used). Preparation of ICP Calibration Standards and Blanks Scandium is used as an internal standard; other elements and/or concentrations can be utilized; adjust accordingly (see Note). Label and date all standard and blank solution containers. 5 of 12 961-12 Lithium Tetrabo

33、rate Calibration Standard for Aluminum and Silicon A solution of fused NIST 99b is used to calibrate the ICP for the determination of aluminum and silicon. This is used because of difficulties encountered with the accuracy and stability of commercial aqueous silicon standards. 1. Dry a portion of NI

34、ST 99b in an oven at 105C for 2 hours, remove and place in a desiccator to cool. 2. Weigh 0.15 0.01 g, to the nearest 0.0001 g, of dried NIST 99b into a platinum crucible. 3. Weigh 1.50 0.02 g, to the nearest 0.01 g, of lithium tetraborate into the platinum crucible, using a top-loading balance. Rot

35、ate and tilt the crucible by hand to mix the material with the lithium tetraborate flux. 4. Place the crucible on a triangle and heat with a blast burner for a minimum of 30 minutes, occasionally checking for unfused material as evidenced by white specks in the melt. The fusion is complete when the

36、melt is entirely clear. The fusion can also be performed in a muffle furnace set at 1000C, or by using an automated fusion apparatus (fluxer). If unfused sample is detected, mix the hot melt by rotating and tilting the hot crucible with tongs, and continuing fusion until it is complete. 5. Remove th

37、e crucible from the flame using the platinum tipped tongs, place it upright in a 250-mL quartz beaker and allow to cool for about 5 minutes. 6. Place a stir bar inside the crucible and add 5% hydrochloric acid so that the crucible is submerged by about 10 mm. 7. Cover the beaker with a watch glass a

38、nd place it on a stirring hot plate. Adjust the heat to achieve mild boiling and the stirrer to achieve a vortex in the solution. 8. Continue heating until the fusion melt has completely dissolved, usually within 10 minutes after boiling begins. Carefully check the crucible and the beaker for any pa

39、rticulates, indicating undissolved NIST 99b. If any doubt remains as to the completeness of the fusion or dissolution of the melt, discard the solution and start over at Step 1. 9. Remove the beaker from the hot plate and allow it to cool. Using the 5% hydrochloric acid from the wash bottle and a fu

40、nnel, quantitatively transfer the beaker contents into a 500-mL volumetric flask. The crucible is to remain in the beaker. Use the wash bottle to wash the interior and exterior walls of the crucible as well as the beaker walls during transfer. 10. Pipet 2 mL of the 500-g/mL scandium solution into th

41、e volumetric flask. 11. Allow the solution to cool to ambient temperature and then dilute to the mark with 5% hydrochloric acid. Stopper and invert several times to mix thoroughly and then transfer the solution to a labeled and dated 500-mL FEP bottle for storage. 12. Calculate the aluminum and sili

42、con concentrations using Equation 1: 500CW 10,000 = g/mL ion,Concentrat Alor Si (1) where: C = certified value for Si or Al in NIST 99b, mass-% W = mass of dried NIST 99b taken (Step 2), g 6 of 12 961-12 500 = volumetric flask volume, mL 10,000 = factor to convert mass-% to g/g 13. Calibrate the ICP

43、 with the new NIST 99b standard solution as described in Sample Analysis and compare to the old, previously utilized standard solution. The results should agree within 2% (relative) of certified values. For the initial establishment of a calibration curve, also fuse and analyze a portion of NIST 99b

44、 as an unknown. The values should be within 2% relative of the certified values. If the values returned for the unknown NIST 99b portion are too low, the fusion of the unknown portion was incomplete. If the values are too high, the fusion for the calibration standard was incomplete. Lithium Tetrabor

45、ate Calibration Standard Blank 1. Weigh 1.50 0.02 g, to the nearest 0.01 g, of lithium tetraborate into a 500-mL volumetric flask. 2. Add approximately 100 mL of 5% hydrochloric acid to dissolve the powder. Heat on a hot plate set at 200C until dissolved. 3. Pipet 2 mL of 500-g/mL scandium solution

46、into the volumetric flask. 4. Allow the solution to cool to ambient temperature and dilute to the mark with 5% hydrochloric acid. Stopper and invert several times to mix thoroughly and then transfer the solution to a labeled and dated 500-mL FEP bottle for storage. The calibration standard and blank

47、 are stable for three months. Make up new calibration solutions when the ones in use are about 75% consumed or are older than three months. A blank is necessary due to trace levels of silicon and aluminum found in commercial batches of lithium tetraborate and for matrix matching. This blank is also

48、to be used for diluting samples where the Al or Si concentration is above the concentration in the NIST 99b standard calibration solution. Because of varying contamination levels, the blank and calibration solutions are to be made using the same lot of lithium tetraborate. When starting to use a new

49、 lot of lithium tetraborate, make up a new calibration standard and blank. Calibration Stock Solutions 1. Prepare 500 mL of each of the three calibration stock solutions by pipetting the volumes of the element concentrate solutions indicated in Table 3 into 500-mL PMP volumetric flasks. 2. Using a graduated cylinder, add 25 mL of concentrated hydrochloric acid to each flask, then carefully add water to fill the flasks half full and swirl to mix the contents. 3. Add 5 mL of concentrated hydrofluoric acid to calibration solution 2