UOP 303-2007 IMPURITIES IN CATALYSTS BY ICP-AES.pdf

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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 1963, 1976, 1987, 2005, 2007 UOP LLC.

3、All rights reserved. Nonconfidential 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, 6

4、10.832.9555 FAX, or 610.832.9585 PHONE. Impurities in Catalysts by ICP-OES UOP Method 303-07 Scope This method is for determining trace metals in fresh, regenerated and spent alumina-, silica-, or aluminosilicate- (silica/alumina-) based catalysts by Inductively Coupled Plasma - Optical Emission Spe

5、ctroscopy (ICP-OES). Ordinarily, the metals determined include: calcium (Ca), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), silicon (Si), sodium (Na), tin (Sn), titanium (Ti), vanadium (V), and zinc (Zn). Silicon is not d

6、etermined when it is a component of the catalyst base. Arsenic (As) and phosphorous (P) can be determined but are not ordinarily present on fresh catalysts. They may, however, be present on regenerated or spent catalyst. Barium (Ba) and mercury (Hg) cannot be determined because barium sulfate precip

7、itates and mercury volatilizes. Mercury can be determined by UOP Method 894, “Mercury in Catalysts by GF-AAS.” Barium can be determined using the fusion technique described in UOP Method 926, “Silicon and Aluminum in Fresh Catalysts by Lithium Tetraborate Fusion/ ICP-OES.” Other elements also can be

8、 determined, if required. The specified elements can be determined within the concentration ranges listed in Table 1. Typical concentration ranges are 0.005-1.0 mass-%. Table 1 Applicable Concentration Ranges, mass-% Element Concentration Range on Catalyst Element Concentration Range on Catalyst, As

9、 0.020-1.0 Na 0.005-2.0 Ca 0.001-2.0 Ni 0.005-1.0 Co 0.005-2.0 P 0.010-1.0 Cr 0.005-1.0 Pb 0.010-1.0 Cu 0.001-0.50 Si* 0.005-0.20 Fe 0.005-2.0 Sn 0.010-1.0 Mg 0.001-0.50 Ti 0.005-2.0 Mn 0.001-0.50 V 0.003-1.0 Mo 0.005-1.0 Zn 0.005-0.50 *See Note 1 2 of 12 303-07 This method is not applicable to nobl

10、e metals and modifiers on catalysts. Noble metals and modifiers can be determined by UOP Method 873, “Noble Metals and Modifiers in Catalysts by ICP-AES.” This method cannot be used for determining metals in alpha-alumina based catalyst because alpha-alumina is not solubilized under the conditions o

11、f this procedure. An alternative microwave-based dissolution technique is described in the Appendix. References ASTM Method D 1193, “Specification for Reagent Water,” www.astm.org ASTM Method D 4307, “Preparation of Liquid Blends for Use as Analytical Standards,” www.astm.org UOP Method 873, “Noble

12、Metals and Modifiers in Catalysts by ICP-OES,” www.astm.org UOP Method 879, “Aluminum in Catalysts by Atomic Absorption,” www.astm.org UOP Method 894, “Mercury in Catalysts by GF-AAS,” www.astm.org UOP Method 926, “Silicon and Aluminum in Fresh Catalysts by Lithium Tetraborate Fusion/ ICP-OES,” www.

13、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 of Method The catalyst samples are decomposed by digestion in acids. Hydrof

14、luoric acid is used to remove silica from silica- or silica/alumina-based catalyst digests by volatilization. Scandium is added to the digests as an internal standard. The sample solutions are then analyzed by ICP-OES with appropriate, matrix-matched standards. Apparatus References to catalog number

15、s and suppliers are included as a convenience to the method user. Other suppliers may be used. Balance, readability 0.1-mg Beaker, Teflon PTFE, 250-mL, Fisher Scientific, Cat. No. 02-593-5B Bottle, wash, for water, 500-mL, VWR, Cat. No. 16651-187 Catalyst grinding equipment (optional, see Sample Pre

16、paration) Balls, grinding, 11.1-mm (7/16-inch), tungsten carbide, SPEX Industries, Inc., Cat. No. 8004A Container, grinding, 57 64 mm (2-1/4 2-1/2 inches), tungsten carbide, SPEX Industries, Inc., Cat. No. 8004 Mixing mill, shaker type, SPEX Industries, Inc., Cat. No. 8000 Cylinders, graduated, poly

17、propylene, 10- and 100-mL, Fisher Scientific, Cat. Nos. 08-570-21A and -21D, respectively Flasks, volumetric, polypropylene, Class B, 100-, 200-, and 500-mL capacity, Fisher Scientific, Cat. Nos. 10-198-50B, -50C, and -50E, respectively; several of each are required 3 of 12 303-07 Hot plate, variabl

18、e heat to at least 250C, Fisher Scientific, Cat. No. 11-600-49H Pipet, microliter, 2500-L capacity, Rainin Instrument Co., Cat. No. EP-2500 Pipet, 10-mL capacity, Rainin Instrument Co., Cat. No. EP-10ML Pipets, volumetric, transfer, Class A, 5-, 10-, 15-, 20-, 25- and 50-mL, Fisher Scientific, Cat.

19、Nos. 13-650-2F, -2L, -2M, -2N, -2P, and -2S, respectively Regulator, argon, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Regulator, nitrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 31

20、22-580 Spectrometer, polychromatic, Inductively Coupled Plasma-Optical Emission Spectrometer, having sufficient resolving power and dispersion to separate the analytical lines in the 160- to 800-nm region. The instrument should be capable of performing background corrections, blank corrections, and

21、weight/volume and dilution calculations. A commercial grating spectrometer with a band pass of 0.018 nm or less in the first order is satisfactory. PerkinElmer, Optima 5300 V. Thermometer, digital, capable of measuring to at least 150C, to measure hot plate temperature, Fisher Scientific, Cat. No. 1

22、5-077-9E Watch glass, Teflon PTFE, 75-mm diameter, Fisher Scientific, Cat. No. 02-610-5C 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 ASTM D 1193 Type I reagent grade water.

23、Argon, 99.995% minimum purity, ICP feed gas Droppers, disposable, polypropylene, Fisher Scientific, Cat. No. 13-711-10 Gloves, neoprene/natural rubber, Fisher Scientific, Cat. No. 11-394-114 Hydrochloric acid, concentrated, Certified ACS Plus, Fisher Scientific, Cat. No. A144-212 Hydrofluoric acid,

24、concentrated, ACS Reagent, J. T. Baker, Mallinckrodt Baker, Cat. No. 9560 Hydrogen peroxide, 30%, Certified ACS, Fisher Scientific, Cat. No. H325-500 Nitric acid, concentrated, Certified ACS Plus, Fisher Scientific, Cat. No. A200-212 Nitrogen or Argon, 99.99% minimum purity, ICP optics purge gas Pip

25、et tips, disposable, for EP-2500 microliter pipet, Rainin Instrument Co., Cat. No. RC-2500 Pipet tips, disposable, for EP-10ML pipet, Rainin Instrument Co., Cat. No. RC-10ML Single element standard, Aluminum (Al), 10,000 g/mL, SPEX Industries, Inc., Cat. No. PLAL1-3X, used for matrix matching Single

26、 element standard, Scandium (Sc), 1000 g/mL, SPEX Industries, Inc., Cat. No. PLSC-2, internal standard Single element standards, 1000 g/mL each, As, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Na, Ni, P, Pb, Si, Sn, Ti, V, and Zn, SPEX Industries, Inc., Cat. Nos. PLAS2-2X, PLCA1-2X, PLCO2-2X, PLCR1-2X, PLCU2-2X

27、, PLFE2-2X, PLMG2-2X, PLMN2-2X, PLMO9-2X, PLNA2-2X, 4 of 12 303-07 PLNI2-2X, PLP9-2X, PLPB2-2X, PLSI9-2X, PLSN5-2X, PLTI9-2X, PLV2-2X, and PLZN1-2X, respectively Sulfuric acid, concentrated, Certified ACS Plus, Fisher Scientific, Cat. No. A300-212 Water, ASTM D 1193 Type I reagent grade water Proced

28、ure Caution: All subsequent steps involving additions of acids and heating of samples and digests must be performed in a properly operating fume hood, using appropriate precautions. Gloves, safety glasses, goggles, and/or face shield, and other appropriate personal protective equipment must be worn.

29、 See the material safety data sheet (MSDS) and local regulations for each material used. The analyst is expected to be familiar with general laboratory practices, the technique of ICP-OES, and the equipment being used. Preparation of Standards To ensure accurate blending, use the techniques describe

30、d in ASTM Method D 4307, “Preparation of Liquid Blends for Use as Analytical Standards.” It has been found convenient to use volumetric pipets for the preparation of the Stock Solutions, and to use microliter pipets thereafter, although volumetric pipets may be used throughout except where hydrofluo

31、ric acid (HF) is present. A few Single Element Standards contain a trace of HF and will be so labeled. For these, use only microliter pipets with disposable tips. If the microwave digestion procedure as described in the Appendix is to be used in place of the sample preparation described on Page 6, a

32、djust the acid matrix in the Calibration Standards to fit the acids used in the microwave dissolution. Prepare four Stock Solutions from the Single Element Standards as follows: 1. Into each of four 500-mL polypropylene volumetric flasks, pipet 25 mL of the Single Element Standards, distributed as s

33、hown in Table 2. Four different Stock Solutions are required to prevent solubility and spectral interference problems. Table 2 Elements Contained in the Stock Standard Solutions Std. 1 Std. 2 Std. 3 Std. 4 Arsenic (As) Tin (Sn) Molybdenum (Mo) Sodium (Na) Calcium (Ca) Phosphorous (P) Chromium (Cr) S

34、ilicon (Si) Cobalt (Co) Titanium (Ti) Copper (Cu) Iron (Fe) Magnesium (Mg) Manganese (Mn) Nickel (Ni) Lead (Pb) Vanadium (V) Zinc (Zn) 5 of 12 303-07 2. Using a graduated cylinder, add 5 mL of nitric acid to each flask. Fill to the mark with water. Cap and mix by inverting several times. 3. Label th

35、e flask as containing 50 g/mL of each of the elements added. Stock Solutions are typically stable for six months. ICP Calibration Standard solutions are prepared by diluting the Stock Solutions. In addition, a solution containing aluminum is added to match the Calibration Standard matrix with the sa

36、mple matrix. If a variety of samples are to be analyzed, it is advantageous to prepare several sets of Calibration Standards. In practice, a total of four sets are sufficient, with 25-mL, 17-mL, 8-mL, and zero-mL Aluminum Single Element Standard added. If the concentration of aluminum is not known,

37、analyze the sample by UOP Method 926, “Silicon and Aluminum in Fresh Catalysts by Lithium Tetraborate Fusion/ICP-OES.” Prepare four Calibration Standards from the Stock Solutions as follows: 1. Into each of four 100-mL polypropylene volumetric flasks, pipet 20 mL of the respective Stock Solutions. U

38、se a fifth 100-mL polypropylene volumetric flask as a blank. 2. If the samples to be analyzed are alumina-based catalysts, pipet 25-mL of the 10,000 g/mL Aluminum Single Element Standard to each of the five volumetric flasks. If the samples are silica/alumina or silica-based, add correspondingly les

39、s Aluminum Single Element Standard. If the samples are silica-based, add no Aluminum Single Element Standard. For many samples, the alumina concentration is known and can be matrix matched. If the alumina concentration is unknown, analyze the sample digest by preparing a Calibration Standard solutio

40、n of 1000-g/mL Al, 5-g/mL Sc, and the acids as described herein, and by analyzing the digest against this Working Standard. To deliver 25 mL to the volumetric flask using the specified 10-mL pipet will require successively pipetting 10-, 10-, and 5-mL. 3. Using graduated cylinders, add 5 mL of sulfu

41、ric acid and 10 mL of hydrochloric acid to the volumetric flasks. 4. Using a pipet, add 0.5 mL of 1000 g/mL Sc Single Element Standard solution to the flasks. Fill to the mark with water. Cap and mix by inverting several times. 5. Label the volumetric flasks as containing 10 g/mL of each of the elem

42、ents added, 5 g/mL Sc, and indicate the concentration of Al. Calibration Standards should be discarded after one month. Since the response of the ICP-OES is linear within the defined range of quantitation, single point standards are used. Preparation of Spectrometer Start up the instrument and ignit

43、e the plasma according to the manufacturers recommendations. For instruments that have both axial and radial view options, use the radial view. Wait a minimum of 30 minutes after the plasma is ignited for the instrument to stabilize. When recommended by the manufacturer, perform a wavelength calibra

44、tion prior to the start of the analysis. Aspirate the Calibration Standard solutions and the reagent blank. Table 3 lists recommended wavelengths to be used for the analyses. Calibration Establish the elemental responses compared to scandium. These calculations are performed by the data system after

45、 the analyst enters the appropriate values for weights and dilution volumes. 6 of 12 303-07 Sample Preparation The number of steps required to prepare samples for analysis depends on whether silica is a constituent, whether organic compounds or carbon are present, and if the catalyst contains platin

46、um group metals. See Notes. Samples are analyzed on an as received (AR) basis unless otherwise specified. If a sample is to be analyzed on a volatile free (VF) basis, weigh portions of the sample both for this test and for LOI at the same time. Analyze the LOI aliquot by UOP Method 954, “Loss on Ign

47、ition (LOI) for Fresh, Regenerated, Used, and Spent Catalysts, Catalyst Supports, and Adsorbents.” Table 3 Recommended Wavelengths Element , nm Element , nm Element , nm As 193.795 Mg 285.213 Si 251.611 Ca (0.1%)* 393.366 Mn 257.610 Sn 189.989 Ca (0.1%)* 422.673 Mo 202.030 Ti 323.452 Co 238.892 Na 5

48、89.592 V 292.402 Cr 205.552 Ni 231.604 Zn 213.856 Cu 324.754 P 213.618 Fe 238.204 Pb 220.353 *Different wavelengths are used for calcium, depending upon its concentration. Calibrate at both wavelengths. Prepare samples according to the following procedure. An alternative microwave-based dissolution

49、technique is described in the Appendix. 1. Samples are not typically ground because of the risk of contamination from the grinding equipment. However, grinding the sample will homogenize the sample and reduce the dissolution time. If the sample is to be ground, grind it in a mixing mill to a consistency of approximately 80 mesh or finer. 2. Weigh, to the nearest 0.1 mg, approximately 1.0 g of sample into a tared 250-mL Teflon beaker. Using graduated cylinders, add 10 mL of water and 10 mL of concentrated sulfuric a