1、 NICKEL, TUNGSTEN, SODIUM AND ALUMINUM IN HYDROCRACKING CATALYSTS BY ICP-AES UOP Method 924-00 SCOPE This method is for determining nickel(Ni), tungsten(W), sodium(Na) and aluminum(Al) in fresh alumina or alumino-silicate supported catalysts by inductively coupled plasma atomic emission spectroscopy
2、 (ICP-AES). The method is suitable for the determination of elements from the low ppm to high mass percent concentration ranges. The determination of Ni, W, Na and Al is described herein, however, many other elements which are brought into solution during the described sample decomposition can be al
3、so determined. Because of incomplete dissolution, catalysts containing alpha- or theta-alumina phases cannot be analyzed by this method, however, it can be applied if a modified sample dissolution technique, such as a TeflonTMlined pressure vessel (not described herein) is utilized. This method can
4、also be used for spent catalyst after suitable pretreatment. OUTLINE OF METHOD Samples are ground and dissolved using sulfuric and hydrofluoric acids. The digest is aspirated into an ICP-AES spectrometer equipped with a sample transport system that is resistant to hydrofluoric acid(HF). The concentr
5、ations of Ni, W, Na, Al and other metals of interest are determined by comparison to standards containing the same acid concentration as the sample solutions. Results are generally reported on a volatile-free basis; 500C Loss on Ignition (LOI) is determined using UOP Method 412. APPARATUS References
6、 to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Balance, readability, 0.1-mg Beaker, Teflon, 250-mL, Fisher Scientific, Cat. No. 02-593-5B IT IS THE USERS RESPONSIBILITY TO ESTABLISH APPROPRIATE PRECAUTIONARY PRACTICES AND TO DETERMINE
7、 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 PRESCRIBED HEREIN CAN BE HAZARDOUS. MATERIAL SAFETY DATA SHEETS (MSDS) OR EXPERIMENTAL MATERIAL SAFETY DA
8、TA SHEETS (EMSDS) FOR ALL OF THE MATERIALS USED IN THIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). COPYRIGHT 1992, 2000 UOP LLC ALL RIGHTS RESERVED UOP Methods are available through ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
9、onshohocken PA 19428-2959, 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. 2 of 8 924-00 Beaker cover, Teflon, 80-mm., Fisher Scientific, Cat. No. 02-617-1G Crucible, qua
10、rtz, 20-mL, Fisher Scientific, Cat. No. 08-072C (for spent catalyst only) Cylinders, graduated, polypropylene, 10- and 50-mL, Fisher Scientific, Cat. Nos. 08-570-21A and 08-570-21C, respectively Fume hood, laboratory Gloves, nitrile or neoprene Hot plate, variable heat to at least 300C Inductively C
11、oupled Plasma-Atomic Emission Spectrometer, PerkinElmer Optima 3000 or equivalent, equipped with a HF resistant sample transport system Mill, coffee mill type, capable of grinding catalyst to 80 mesh. Proctor - Silex E160B, or equivalent, local supply Muffle furnace, capable of operation to a minimu
12、m of 500C (for spent catalyst only) Pipets, glass, Class A, 5-, 15-, 50-mL, Fisher Scientific, Cat. Nos. 13-650,2F, -2M, -2S, see NOTE Regulator, argon, two-stage, high purity, Matheson Gas Products, Model 3122-580 Regulator, nitrogen, two-stage, high purity, Matheson Gas Products, Model 3122-580 Si
13、eve, wire cloth, brass frame, 8-inch diameter, 2-inch depth, U.S. standard sieve, No. 80, Fisher Scientific, Cat. No. 04-881W; with cover and pan, Fisher Scientific, Cat. Nos. 04-886A and B, respectively Thermometer, electronic, with surface temperature probe, Omega Engineering, Cat. Nos. HH81 and 8
14、8108K, respectively Volumetric flasks, Nalgene polymethylpentene, 500-mL, Fisher Scientific, Cat. No. 10-198-52F REAGENTS AND MATERIALS References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Aluminum solution, 1000-g/mL, Spex, Cat.
15、No. PLAL1-2X Argon, 99.995% minimum purity, ICP feed gas Hydrofluoric acid, concentrated, Reagent ACS Grade, Fisher Scientific, Cat. No. A147-1LB Nickel solution, 1000-g/mL, Spex, Cat. No. PLNI-2X Nitrogen, 99.99% minimum purity, water/oil free, ICP optics purge gas Scandium solution, 1000-g/mL, Spe
16、x, Cat. No. PLSC2-2X (to be used as an internal standard) Sodium solution, 1000-g/mL, Spex, Cat. No. PLNA1-2X 3 of 8 924-00 Sulfuric acid, concentrated, Certified ACS Plus Grade, Fisher Scientific, Cat. No. A300-212 Sulfuric acid, 1:1, Fisher Scientific, Cat. No. LC25640-3. Or, mix equal parts of co
17、ncentrated sulfuric and water; slowly add the acid to the water. Tungsten solution, 1000-g/mL, Spex, Cat. No. PLW9-2X. This solution contains (NH4)2WO4in water, no HF. See NOTE. Water, deionized PROCEDURE The analyst is expected to be familiar with the basic instrumentation and concepts of ICP-AES.
18、The method describes a beaker based sample dissolution of fresh catalyst. Other techniques, such as microwave, can be used for dissolution assuming equivalency. All steps involving handling and heating of concentrated acids or acid solutions must be performed in a fume hood. Preparation of Calibrati
19、on Standards A single standard containing the four elements of interest is used to calibrate the ICP. If the determination of additional elements is desired the analyst must check for line overlaps and select emission lines that are free of overlap. The concentration of elements in the calibration s
20、tandards was made up assuming the following catalyst composition: W = 20%, Al = 20%, Ni = 6% and Na = 0.1% The concentration of elements in the calibration standard may need to be changed for different catalyst types. Prepare the ICP calibration solution as follows: 1. Add into two 500-mL plastic vo
21、lumetric flasks, using a plastic graduated cylinder, 20 mL of 1:1 sulfuric and 4 mL hydrofluoric acids. Wash down the walls with water. Label one flask “blank = zero g/mL” and the other “calibration standard.” CAUTION: Appropriate safety precautions must be taken when handling hydrofluoric acid. 2.
22、Pipet into the “calibration standard” 500-mL volumetric flask: a) 50 mL of 1000-g/mL tungsten solution (if HF is present use a plastic pipet) b) 50 mL of 1000-g/mL aluminum solution c) 15 mL of 1000-g/mL nickel solution d) 2 mL of 1000-g/mL sodium solution 3. Wash down the walls with water. 4. Pipet
23、 into both volumetric flasks 5-mL of the 1000-g/mL scandium internal standard solution. When diluted, both flasks will contain 10-g/mL Sc. 5. Dilute both flasks to mark with water, cap and invert to mix thoroughly. The calibration standard will contain: 100-g/mL W, 100-g/mL Al, 30-g/mL Ni and 4-g/mL
24、 Na. This standard is stable for 3 weeks. 4 of 8 924-00 Sample Preparation A reagent blank is carried through the procedure analogous to the sample. A quality control (QC) sample is to be prepared and analyzed with each group of samples. Typically, a large volume of a single sample is retained for u
25、se as a QC sample. 1. Grind the sample in a mill to a uniform powder (80 mesh). The grinding capability of the mill can be determined by pulverizing and then screening similar catalyst types prior to performing this method. 2. For fresh catalysts, proceed to Step 4. For spent catalysts, weigh, to th
26、e nearest 0.1 mg, 0.20 g (0.02 g) of the catalyst into a quartz crucible, and ignite for 1 hr at 500C in a muffle furnace. Generally the results are reported on volatile-free basis, therefore, weigh a sample for a LOI 500C, using UOP Method 412, at the same time as sampling for the acid decompositio
27、n. 3. Quantitatively transfer the ignited powder into a Teflon beaker by rinsing with 20 mL of water. Proceed to Step 6. 4. Weigh, to the nearest 0.1 mg, 0.20 g (0.02 g) of the ground catalyst into a 250-mL Teflon beaker. Generally the results are reported on volatile-free basis, therefore, weigh a
28、sample for a LOI 500C, using UOP Method 412, at the same time as sampling for the acid decomposition. 5. Add, using a graduated cylinder, 20 mL of water to the beaker. This is to wet the catalyst. 6. Add, using a graduated cylinder, 20 mL of 1:1 sulfuric acid to the beaker, and swirl to mix the cont
29、ents. 7. Add, using a polypropylene graduated cylinder, 10 mL of concentrated hydrofluoric acid to the beaker and wash down the beaker walls with water. Appropriate safety precautions must be taken when handling hydrofluoric acid. 8. Place the beaker on a hot plate, 150C, and heat to mild boiling. 9
30、. Slowly increase the hot plate temperature and continue heating until the evolution of thick white fumes characteristic of sulfuric acid. The heating in the presence of HF will volatilize silicon as SiF4from solution. Do not fume excessively; this will volatilize additional sulfuric acid and will m
31、ake it difficult to match the acid concentration in the sample solutions and the standards. The hot plate temperature must not exceed 300C as Teflon will soften and deform. 10. Remove the beaker from the hot plate, cover with a Teflon cover and allow it to cool to room temperature. 11. Partially unc
32、over the beaker, slowly and carefully add, using a graduated cylinder, 20 mL of water. Add the water carefully to avoid loss of sample due to splattering. Inspect the solution for total decomposition, if undissolved matter is present, repeat Steps 7-11. 5 of 8 924-00 12. Rinse the Teflon cover and t
33、he beaker walls with water. 13. Add, using a graduated cylinder, 4 mL of concentrated hydrofluoric acid. 14. Cover the beaker with the Teflon cover and place on the hot plate, 150C, and bring to a boil. 15. Remove the beaker from the hot plate and allow it to cool. 16. Rinse the Teflon cover and the
34、 beaker walls with water. 17. Quantitatively transfer, with water, the contents of the beakers, sample and reagent blank, into 500-mL plastic volumetric flasks. 18. Pipet into the volumetric flasks 5 mL of the 1000-g/mL scandium internal standard solution. 19. Dilute to mark with water, cap and inve
35、rt to mix thoroughly. 20. The samples are now ready for ICP analysis. Sample Solution Analysis Set up the ICP-AES instrument according to the instrument manufacturers guidelines. Table 1 lists the elemental wavelengths that are recommended in this method. Other wavelengths may be used if it can be s
36、hown that method precision and accuracy are not adversely affected. A HF resistant sample introduction system is required for use with hydrofluoric acid. Table 1 Recommended Wavelengths Element Wavelength, nm Ni 231.604 W 248.923 Al 396.152 Na 589.592 Sc 424.683 1. Standardize the instrument by aspi
37、rating the “zero g/mL” standard, followed by the “calibration standard”. Allow sufficient wash-out time between aspirations. 2. Aspirate the reagent blank solution and examine the concentrations for elements of interest, especially Na, as it is present in trace amounts (0.1 g/mL in the sample soluti
38、ons) and is prone to be a contaminant. The concentration (intensity) of Na in the reagent blank should be approximately the same as for the “zero g/mL” solution. If not, clean the equipment again and repeat the procedure. 3. Re-standardize the ICP using the reagent blank as the “zero g/mL” standard.
39、 4. Analyze the sample and QC sample solutions. 6 of 8 924-00 5. To ensure ICP spectrometer performance, aspirate the calibration solution as a calibration check after every 4 - 8 sample solutions and after the last sample. The replication of the calibration solutions should be within 3% relative. I
40、f not, recalibrate the spectrometer and rerun the samples. If this does not help, investigate the sample transport system or other system performance parameters. CALCULATIONS Report the results to three significant figures at one mass-% and above, to two significant figures below one mass-%. Calcula
41、te the concentration of elements in the catalyst on an as received (AR) basis as follows: 410 CVElement, mass %,(AR)W= (1) where: C = concentration of element, g/mL, in sample solution, from instrument printout V = volume from Sample Preparation Step 17 W = weight of sample, from Sample Preparation
42、Step 2 or 4 10-4= factor to convert to mass-% Calculate the concentration of elements in the catalyst on a volatile-free (VF) basis as follows: 100AElement, mass %,(VF)100 %LOI=(2) where: A = concentration of element, mass-%, as received, oEq. 1 % LOI = from analysis of sample by UOP Method 412 If t
43、he results are to be reported as oxides, multiply by the appropriate gravimetric factor in Table 2. Table 2 Gravimetric Factors To Convert Multiply By Ni to NiO 1.272 W to WO31.261 Na to Na2O 1.348 Al to Al2O31.889 7 of 8 924-00 NOTE Ensure that the 1000-g/mL tungsten calibration standard does not c
44、ontain any hydrofluoric acid (HF). If a calibration standard containing HF must be used, use plastic pipet and volumetric flasks, avoiding contact with glass. PRECISION Precision statements were determined using UOP Method 999. ASTM Repeatability A nested design was carried out for determining tungs
45、ten, nickel, aluminum and sodium in catalysts in four laboratories. In each laboratory, two analysts carried out tests on two separate days, performing two tests each day. The total number of tests performed was 32 for each element. Using a stepwise analysis of variance procedure, the within-day est
46、imated standard deviation (esd) was calculated and is listed in Table 3. Two tests performed by the same analyst on the same day should not differ by more than the ASTM allowable difference shown in Table 3 with 95% confidence. UOP Repeatability A nested design was carried out for determining tungst
47、en, nickel, aluminum and sodium in catalysts in four laboratories. In each laboratory, two analysts carried out tests on two separate days, performing two tests each day. The total number of tests performed was 32 for each element. Using a stepwise analysis of variance procedure, the within-lab stan
48、dard deviation (esd) was calculated and is listed in Table 3. Two tests performed in one laboratory by different analysts on different days should not differ by more than the UOP allowable difference shown in Table 3 with 95% confidence. The data in Table 3 are a short-term estimate of repeatability
49、. 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 A nested design was carried out for determining tungsten, nickel, aluminum and sodium in catalysts in four laboratories. In each laboratory, two analysts carried out tests on two separate days, performing two tests each day. The total number of tests performed was 32 for each element. Using a stepwise analysis of variance procedure, the within-lab and between-lab
