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4、2.9585 PHONE. Collection and Grinding of Adsorbents and Catalysts for Analysis UOP Method 918-12 Scope This method is for collecting and grinding adsorbents and catalyst samples to be analyzed by other UOP Methods. Individual methods should be consulted for specific instructions regarding details of
5、 the sample preparation for individual analyses. Reference ASTM Practice D346, “Collection and Preparation of Coke Samples for Laboratory Analysis,” www.astm.org ASTM Practice D2234, “Collection of a Gross Sample of Coal,” www.astm.org Outline of Method A representative bulk sample is selected from
6、a larger lot in one of three ways depending on the origin of the adsorbent or catalyst. From production lots, a representative sample is obtained using established techniques. From research samples, a 200-mL sample, or at least 20% more than is required for the analysis, is obtained by riffling. Fro
7、m spent catalysts, the sample lot is screened to remove extraneous material prior to sampling by an established technique, mixed, and reduced to a 200-mL sample by riffling. If grinding is not required, this representative bulk sample is riffled to obtain a representative analytical sample for the a
8、nalysis. If grinding is required, a specified procedure is followed to produce a representative sample for analysis. Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Bag, plastic, vapor impenetrable, sized appropriat
9、ely for use Balance, top loading, readable to 0.01 g Bottle, polypropylene, Mason jar, 500-, 1000-, 2000-, and 3000-mL, 70-mm mouth, with closure, Fisher Scientific, Cat. Nos. 11-825A, -825B, -825C, and -825D, respectively Bottle, vapor impenetrable, sized appropriately for use Brush, fine sieve, Gi
10、lson Company, Cat. No. TSA-170 2 of 7 918-12 Cutter-sampler, sample divider, with nitrogen purge, sized and constructed according to the specifications summarized in ASTM Practice D2234, “Collection of a Gross Sample of Coal,” Section 7 Cylinders, graduated, 50- and 250-mL, Fisher Scientific, Cat. N
11、os. 08-555C and -555E, respectively Drum thief, slot sampler, Sampling Systems, Cat. No. 1210A-600 (600 mm) or 1201A-1000 (1000 mm) Dust box, constructed from 1/4-inch thick polycarbonate, having two hinged, front opening doors and openings for compressed air, vacuum and two accordion sleeves, see F
12、igure. If hygroscopic catalysts are to be ground in the box, it must be air-tight and fitted with a nitrogen purge. Powder sampler, three zone, 600-mm long, Sampling Systems, Cat. No. 1210B-600, with sample collecting bottle, Cat. No. 8165A-250 Pulverizer, laboratory, capable of grinding catalysts t
13、o 0.17 mm (80 mesh or finer), equipped with a stainless steel screen with herringbone slots of 0.25 mm, Mikro-Pulverizer, Hosokawa Micron For purposes of this method, the terms pulverizer, mill, and grinder are interchangeable. Regulator, air, two-stage, high purity, delivery pressure range 30-700 k
14、Pa (4-100 psi), Matheson Tri-Gas, Model 3122-590 Regulator, nitrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Riffler, manual sample splitter, with scoop and receiver pans. The scoop for adding sample to the riffler must have straight
15、sides equal in length to the effective width of the riffler. The riffler must be fitted with an even number of dividing slots that are of equal width, at least three times the maximum diameter of the whole-pill sample. The slots must discharge alternately to each side of the riffler. The size of the
16、 riffler is governed by the sample size to be divided. It must be possible to distribute the sample evenly across the entire length of the scoop used to add the sample to the riffler. A riffler suitable for 200 mL of sample is available from Thomas Scientific, Cat. No. 8261C10. Riffler, rotary, micr
17、o, Retsch, Model PT100 Sample Divider Spatula, scoop, 300-mm length, Fisher Scientific, Cat. No. 14-375-57 Vacuum cleaner, high efficiency, with HEPA filter, Nilfisk-Advance America, Model GM 80 Reagents and Materials References to catalog numbers and suppliers are included as a convenience to the m
18、ethod user. Other suppliers may be used. Air, 200 kPa minimum delivered pressure, less than 2.0 ppm water Nitrogen, high purity, less than 1.0 ppm oxygen, less than 1.0 ppm water Sample Collection Catalyst Screening All catalyst is screened at the plant prior to sampling to remove extraneous materia
19、l. Fresh oxidized catalyst that will be reduced is passed directly through a screening unit from the product 3 of 7 918-12 accumulation hopper. Reduced and sulfided catalysts are screened following reduction or sulfiding. Spent catalyst is screened to remove extraneous material such as ceramic space
20、rs. Fresh Catalyst from Production Lots 1. Purge an appropriately sized clean bottle or plastic bag with dry nitrogen and cap or seal. 2. Sample the entire production lot of fresh catalyst using an established technique. Cutter sampling according to the procedure described in ASTM Practice D2234 (se
21、e Note 1). Condition IB-1 is an example technique. Withdrawing small regularly spaced portions from a moving sample stream is generally recognized as the easiest, most effective procedure for collecting representative samples of large lots. If a cutter-sampler is used, the sample or increment size i
22、s controlled by the cutter-sampler size, the frequency of the pass and speed of transverse. The number of increments should be selected so as to obtain a representative sample of the production lot; generally one per drum. 3. Layer the sample in the bottle or plastic bag as the samples are taken and
23、 cap the bottle or seal the plastic bag when the lot is complete. This sample is often referred to as the gross sample. 4. Pour the contents of the bottle or plastic bag into a large plastic bag while maintaining a dry nitrogen purge. 5. Mix the contents of the bag to destroy the layering characteri
24、stics of the sample by splitting and recombining the sample five times using the manual sample splitter. 6. Divide the entire sample by successive riffling to obtain a 200-mL analytical sample plus an appropriate quantity of a retained sample, using the procedure described in ASTM Practice D346, “Co
25、llection and Preparation of Coke Samples for Laboratory Analysis,” Procedure A (see Notes 1, 2, and 3), and a properly sized riffler. 7. Store the retain of the sample appropriately. Adsorbents from Production Lots Obtain a representative sample by established techniques. Cutter sampling and rifflin
26、g as described under Fresh Catalyst from Production Lots are examples of techniques. Experimental Adsorbents and Catalyst Divide the entire, well mixed experimental sample to obtain a 200-mL sample by successive riffling, using the procedure described in ASTM Practice D346, Procedure A (see Notes 1,
27、 2, and 3), and a properly sized riffler. If the lot volume of the sample is smaller than 200 mL, or if a limited quantity of sample is available for analysis, a representative sample that exceeds the minimum sample size actually required for the analysis by at least 20% is obtained from the entire,
28、 well-mixed experimental sample by riffling according to ASTM Practice D346, Procedure A (Notes 1, 2, and 3). Spent Catalyst Each spent catalyst shipment is screened in the catalyst receiving plant and four fractions are obtained: oversize, on-size, fines and dust. The on-size material, fines and du
29、st may afford one or more analytical samples depending on the size of the shipment. The oversize material is not sampled for analysis. The analytical samples are obtained as follows: 4 of 7 918-12 If a precursory inspection of the spent catalyst is required, it may be performed as follows: Count the
30、 number of drums in the spent catalyst shipment. Determine the square root of the total number of drums in the spent catalyst shipment to calculate the number of drums that require sampling. Using the drum-thief, sample that number of drums of the shipment combining each increment in an appropriatel
31、y sized bottle or plastic bag. Mix the gross sample well by randomly shaking for 5 minutes in a tightly capped or sealed container. 1. Collect the fines (broken pills and chips) into drums and sample by either using a cutter-sampler as described in Steps 1 through 7 of Fresh Catalyst from a Producti
32、on Lot or by sampling each drum with a drum-thief, combining each increment in an appropriately sized container and mix well. This sample is often referred to as the fines gross sample. 2. Collect the dust collected by the dust collectors and sample using a drum-thief. 3. Sample the on-size catalyst
33、 using a cutter-sampler according to Steps 1 through 7 described under Fresh Catalyst from a Production Lot. The on-size catalyst may be separated into parts depending on the size of the shipment. This sample is often referred to as the on-size gross sample. Sample Selection and Preparation Grinding
34、 Not Required Riffle the representative sample down to the sample size required for the determination using a properly sized riffle and riffling procedure as described in ASTM Practice D 346, Procedure A. Grinding of Hygroscopic Samples Follow the procedure detailed in Grinding of 200-mL Samples or
35、Grinding of Samples When Less than 200 mL is Available, in an air-tight dust box or glove box, respectively, with a dry nitrogen purge. Grinding of 200-mL Samples Pulverizer Set-up and Cleaning 1. Set up the pulverizer and install it in a dust box, glove box, fume hood or other appropriate location.
36、 The pulverizer must be set up in such a manner as to prevent the release of dust into the environment during pulverizer cleaning and sample grinding. 2. Use a high-efficiency vacuum and a pressurized air line for cleaning the grinder. 3. Clean the pulverizer thoroughly to remove any material remain
37、ing from grinding of the previous sample. The cleaning must be performed in such a manner to prevent inhalation of the dust. Verify that the power to the pulverizer is off and lock out the power switch. It is important to remove as much dust as possible from inside the mill housing, especially behin
38、d the grinder blades. 4. Reassemble the pulverizer. Examine the seals for any sign of wear and replace, if necessary. Sample Grinding Grind the representative bulk sample as follows: 1. Verify that the pulverizer has been cleaned as described in Pulverizer Set-up and Cleaning. Clean if necessary. 5
39、of 7 918-12 2. Riffle out a representative portion of 50 mL of the sample to be ground from the well mixed representative sample. The optimal sample size for grinding is 200 mL. Larger samples may be ground if the equipment is sized appropriately. This first 50-mL portion of sample is to be used as
40、a “mill wash and is intended to precoat the interior surfaces of the pulverizer and simultaneously serve as a test for any dust leaks. 3. Attach a clean, appropriately sized receiver to the pulverizer to receive the “mill wash. 4. Turn on the properly assembled pulverizer. Appropriate safety precaut
41、ions must be taken when operating the pulverizer. If a dust box is used, the doors are closed and the vacuum is attached to the dust box (see Figure) and turned on. 5. Feed a few particles of the “mill wash through the mill and watch for any dust escaping around the gaskets on the frontal feeder doo
42、r, the side door and the receiver. 6. Tighten or reassemble any section of the pulverizer from which any dust was observed to escape. 7. Repeat Steps 5, 6 and 7 until no further dusting is observed. 8. Grind the balance of the “mill wash sample to a consistency of less than 0.17 mm (80 mesh) by a si
43、ngle pass through the pulverizer. Collect the portion of the “mill wash that falls into the receiver, leaving the remainder in place as a coating inside the mill. This procedure affords a powder that passes approximately 90% through 200 mesh. Good laboratory practice suggests that the pulverizer mil
44、l be checked periodically to verify that it is producing the desired mesh size by grinding a sample and checking the mesh size by an appropriate technique such as wet sieving. 9. Turn off the pulverizer, remove the receiver containing the “mill wash and dispose of the “mill wash sample. 10. Attach a
45、 clean, appropriately sized receiver to the pulverizer to receive the balance of the gross sample. 11. Turn on the pulverizer. 12. Feed a few particles of the balance of the gross sample through the pulverizer and watch for any escaping dust from the gasket around the receiver. Tighten or reattach t
46、he receiver if any dust was observed leaking from the gasket and verify that no further dust is leaking. 13. Grind the balance of the sample by a single pass through the pulverizer. Collect only that portion of the sample which freely collects in the receiver. Approximately 98-100% of the balance of
47、 the sample should be recovered. If a dust box is used, the vacuum is turned off when grinding is complete. 14. Open the receiver or plastic bag without agitating it and scoop out the portion required for the analysis. 15. Clean the pulverizer as described in Pulverizer Set-up and Cleaning. Grinding
48、 of Samples When Less than 200 mL is Available 1. Select an alternative means of grinding that is capable of reducing the sample particle size to less than 0.17 mm (80 mesh). Grinders that may be suitable include a mortar and pestle, a shaker mill or a shatter box, but the grinder used must meet the
49、 following requirements: 6 of 7 918-12 o Grinding must be performed without dust loss. o For noble metal analysis the powder must pass through 80 mesh with approximately 90% through 200 mesh. o The grinding device must not contaminate the sample and the sample recovered must be representative. 2. Clean the alternative grinding device by blowing out old powdered samples with air, brushing and then thoroughly clean by grinding and discarding a portion of the catalyst not required for the analysis. Care should be taken to av
