UOP 99-2007 PENTANE-INSOLUBLE MATTER IN PETROLEUM OILS USING A MEMBRANE FILTER.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 1947, 1963, 1982, 2007 UOP LLC. All ri

3、ghts reserved. 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 FA

4、X, or 610.832.9585 PHONE. Pentane-Insoluble Matter in Petroleum Oils Using a Membrane Filter UOP Method 99-07 Scope This method is for the determination of pentane-insolubles in petroleum oils and is applicable to samples that are fluid at about 37C or lower temperatures. This method covers the rang

5、e of 0.01 to about 20 mass-% pentane-insolubles. Solid particulate materials interfere. The data provided by this method may be used as an index to coking tendency of petroleum oils when considering their suitability as charge stocks to cracking or other processes. More viscous or solid materials su

6、ch as asphalts may be handled by using the modification described in the Appendix. A similar test method for heptane-insolubles, for samples that are fluid at 80C, is UOP Method 614, “Heptane-Insoluble Matter in Petroleum Oils by Membrane Filtration,” which also mentions toluene-insolubles in a Note

7、. ASTM Method D 4055, “Pentane Insolubles by Membrane Filtration,” is also similar in technique, but is written for particulates in lubricating oils rather than asphaltenes. References ASTM Method D 56, “Flash Point by Tag Closed Cup Tester,” www.astm.org ASTM Method D 4055, “Pentane Insolubles by M

8、embrane Filtration,” www.astm.org UOP Method 614, “Heptane-Insoluble Matter in Petroleum Oils by Membrane Filtration,” www.astm.org Outline of Method A weighed sample is dispersed at ambient temperature in n-pentane, digested at 37C, and filtered through a weighed membrane filter. Samples that canno

9、t be completely dispersed cannot be analyzed. The membrane filter is dried and reweighed to obtain the weight of insoluble matter. 2 of 10 99-07 Definition Asphaltenes are defined as the material present in oil fractions that is not soluble in light paraffinic solvents. They are fine, powdery, black

10、-brown solids which are polymeric materials spanning a wide range of molecular weights. Their chemical composition is quite complicated. They appear to be closely associated with high molecular weight semi-polar naphthenic materials. The terms “pentane- insolubles” and “asphaltenes” are often used s

11、ynonymously. Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used, unless stated otherwise. Balance, readability 0.1-mg, capacity 200-g Clamps, for 250-mL flasks in shaker bath, Fisher Scientific, Cat. No. 15-455-15E Cyli

12、nder, graduated, 250-mL, Fisher Scientific, Cat. No. 08-557E Desiccator, with plate, to hold Petri dishes, Fisher Scientific, Cat. No. 08-615A Dishes, Petri, borosilicate glass, 60-mm diameter Filter holder, stainless steel, “Millipore Hydrosol“ filter holder, Millipore Corp., Cat. No. XX 20 047 20

13、Flask, filtering, with sidearm, 2-L, Fisher Scientific, Cat No. K953760-2000 Flask, Erlenmeyer, narrow neck, 250-mL, with pennyhead, ground-glass, standard taper stopper, Fisher Scientific, Cat. No. 10-100E Forceps, stainless steel, with flat, polished tips for handling filters, Millipore Corp., Cat

14、. No. XX62 000 06 Gloves, thermal resistant, Fisher Scientific, Cat No. 11-462-56 Oven, capable of operation at 95C, Fisher Scientific, Cat No. 13-247-637G Pipet, volumetric transfer, 2-mL, Fisher Scientific, Cat. No. 13-650-2C. Cut 4-5 mm off the tip to obtain a large-bore tip. Pipet, 25-mL graduat

15、ed serological, large tip opening, Fisher Scientific, Cat. No. 13-671-108E Pipet filler, Fisher Scientific, Cat. No. 03-692-35 Pump, vacuum, Welch Rotovap, Fisher Scientific, Cat. No. 01-129-19. If the pump is to be located in the hood, or anywhere near the warmed pentane, an explosion proof model s

16、uch as Fisher Scientific, Cat. No. 01-182-003 must be used. Shaker water bath, Precision Scientific Model 50, Fisher Scientific, Cat. No. 15-455-5 Thermometer, for oven, without mercury, Fisher Scientific, Cat. No. 15-041-6C Ultrasonic bath, 9-L capacity, 185 watt, Fisher Scientific, Cat. No. 15-335

17、-110 Wash Bottle, 500-mL, fluorinated HDPE, Fisher Scientific, Cat. No. 03-409-17B Reagents and Materials References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used, unless stated otherwise. 3 of 10 99-07 Depth filter disc, 35-mm diamete

18、r, Millipore Corp., Cat. No. AP2503500, if needed, see Procedure, Step 10 Dessicant, indicating Drierite, Fisher Scientific, Cat. No. 07-578-3A n-pentane, 99% minimum purity, residue after evaporation 0.001%, Acros Organics, Cat. No. 16787 0025, Fisher Scientific Membrane filter discs, 0.8 m and 5.0

19、 m pore sizes, 47-mm diameter, white, plain, MF, Millipore Corp., Cat. Nos. AAWP04700 and SMWP04700, respectively Sampling Samples for this test should be taken in clean containers under a blanket of nitrogen or other inert gas. The container should be filled only about 3/4 full so that the sample c

20、an be shaken vigorously before testing. No other tests or analyses should be made on this sample until after the pentane-insoluble content is determined. Samples under an inert gas blanket can usually be kept a few days at room temperature. However, for best results, test the sample the same day it

21、is taken. Sample Preparation The sampling procedure varies according to two conditions: the expected pentane-insoluble matter content, and the fluidity of the sample. If the sample is sufficiently fluid to withdraw into a pipet, take the sample from the container at room temperature. If the sample i

22、s too viscous, or is waxy, it must be heated. 1. Loosen the cap or stopper of the sample container to vent it and place it in the 95C oven along with the appropriate pipet. CAUTION: If there is any possibility of the sample containing light ends, or if it is of unknown origin, test it for flash poin

23、t by ASTM Method D 56, “Flash Point by Tag Closed Cup Tester,” before placing it in the oven. If it flashes, do not use the oven to heat the sample. 2. Heat small bottles (pint or less) 30 minutes before sampling. Allow one hour of heating for a gallon container. Never heat for more than about 2 hou

24、rs, because some oils can form additional insoluble compounds on prolonged heating (see Note 1). Very high boiling samples, such as asphalts, should be sampled as described in the Appendix. The size of the sample taken for the test and the size of the pores of the membrane filter disc to be used are

25、 determined by the expected content of insolubles in the sample. If the insolubles content is expected to be less than 1.0 mass-% use the 25-mL graduated pipet with the large tip opening to take about 12-13 mL (approximately 10 g) of sample. Use the 0.8 m pore size filter disc for filtering. If the

26、insolubles content is expected to be above 1.0 mass-%, use the tipless 2-mL pipet to take a 0.5-1.5 g sample (Table 1) and use the 5.0 m disc filter for filtering. Procedure The analyst is expected to be familiar with general laboratory procedures and with the equipment being used. CAUTION: All step

27、s involving heated pentane shall be performed in a fume hood. 1. Weigh a 250-mL Erlenmeyer flask to the nearest 0.0001 g. 2. Following the Sample Preparation above, tighten the stopper or cap on the sample container and shake the sample vigorously for 30-50 seconds. 3. Quickly remove the stopper or

28、cap. 4 of 10 99-07 Table 1 Sample Size and Filter Selection Range of Pentane-Insoluble Matter, mass-% Approx. Sample Size, g Filter Pore Size, m 0.01-1.0 1-5 5-20 10 1.5 0.5 0.8 5.0 5.0 4. Insert the end of the pipet into the center of the oil sample and draw an aliquot. Drain the pipet into the fla

29、sk. Avoid getting sample on the ground glass joint. Use gloves if the sample is hot. 5. Allow the flask to come to room temperature and reweigh it to the nearest 0.0001 g. 6. Using a graduated cylinder, add 200 mL of cool (room temperature) n-pentane to the flask. Stopper and shake the flask vigorou

30、sly for at least 2 minutes. 7. Place the flask, loosely stoppered, into the ultrasonic bath for 5 minutes. Remove the flask from the ultrasonic bath after approximately two minutes and again after four minutes, swirl it by hand, and return it to the bath. Observe the bottom of the flask; there shoul

31、d be no sample left clinging to the bottom. If the sample is not completely dispersed, place the flask in the ultrasonic bath for an additional 5 minutes, swirling it occasionally. Continue this procedure until the sample appears to be completely dispersed. The sample must be thoroughly dispersed or

32、 the test is invalid. 8. Place the loosely stoppered flask in the shaker water bath maintained at 37C. Operate the shaker at the maximum rate possible without splashing. Observe the sample several times over a period of 15 minutes. If the sample tends to settle out, place the flask in the ultrasonic

33、 bath and redisperse the sample. Viscous samples may require extended heating and shaking time in the water bath with intermittent ultrasonic treatment to obtain complete dispersal of the sample. 9. Leave the flask in the shaker water bath for a minimum of 60 minutes total digestion time at 37C. Ope

34、rate the shaker at the maximum rate possible, without splashing, during the entire digestion period (see Note 2). 10. Place a membrane filter disc, and depth filter if used, in a clean, dry, previously numbered Petri dish and weigh it to the nearest 0.0001 g. Always handle the filter discs with smoo

35、th-tipped forceps. The depth filter disc is used with black oil samples, which tend to plug the regular filter. The depth filter is weighed along with the regular filter and then placed in the throat of the funnel after the regular filter is in place (Step 13). The analysis then continues as describ

36、ed in the method using both filters. 11. Insert the base of the filter holder in the filtering flask. 12. Place the filter disc on the screen in the base of the filter holder. 13. Attach the top (funnel) of the filter holder and screw it on tightly. 14. Electrically ground both the top and the base

37、of the filter holder to a suitable common ground. The apparatus must be grounded in this fashion to prevent an electrostatic charge from accumulating on the filter cake. 5 of 10 99-07 S)TG(100 The presence of a static charge could cause problems with transferring the filter cake to the balance witho

38、ut loss of insolubles, as well as being a potential safety hazard should a spark be generated. 15. Apply a slight vacuum to the filter, just sufficient to see the filter pulled down onto the plate. Do not use more vacuum than what is absolutely necessary because evaporation of solvent and consequent

39、 chilling of the mixture may occur and cause the wax to precipitate. For convenience, the vacuum pump may be placed outside the hood, with just the vacuum line running into the hood. Vent the outlet of the pump to the hood or other laboratory exhaust. 16. Remove the flask containing the sample from

40、the water bath. Wipe the water from the outside of the flask. 17. Stopper and shake the flask, then pour the contents on the filter. If the amount of insoluble material is high, pour the contents on the filter in aliquots. When the level of the solution has receded to the throat of the funnel, rinse

41、 the flask at least 3 times, using 100 mL of warm (about 37C) pentane the first time, and 50-mL portions subsequently, pouring the washings down the sides of the funnel to wash any sediment onto the filter. The last wash should be colorless; if it is not, continue washing until the washings are colo

42、rless. CAUTION: Pentane has a low flash point. KEEP AWAY FROM OPEN FLAMES. 18. Rinse, with about 100 mL of warm pentane, the sides of the funnel and filter cake until the solids on the filter appear to be dry (see Note 3). 19. With the vacuum still on, unscrew the filter holder and gently remove the

43、 funnel. If the sediment is unusually heavy (greater than 40-50 mg) some of it may tend to cling to the throat of the funnel at the bottom where it meets the filter. Wash this material onto the filter. 20. Examine the filter disc. The outer edge should be only lightly discolored if it was properly g

44、ripped by the holder. Wash the edge of the filter disc with a fine stream of warm pentane to remove any oil that may have seeped under the edge of the holder until the filter appears dry. 21. Turn off the vacuum and disconnect the vacuum line. Hold the Petri dish, in which the disc was originally we

45、ighed, next to and level with the filter. Gently loosen the filter supporting the pentane-insolubles with the tip of the forceps and carefully slide it into the dish. 22. Discard the filtrate in an environmentally safe manner. 23. Place the dish containing the filter into the oven at 95C and heat 10

46、 to 15 minutes. 24. Remove the dish and filter, and cool in a desiccator in order to prevent the filter cake from absorbing moisture, about one hour. 25. Reweigh to the nearest 0.1 mg (see Note 4). Calculations Calculate the concentration of pentane-insolubles using the Equation. where: G = gross we

47、ight of dish, filter (and depth filter, if used) and residue, g S = weight of sample, g T = tare weight of dish and filter (and depth filter, if used), g Pentane-Insoluble Matter, mass-% = 6 of 10 99-07 For values less than 0.10 mass-%, report to three decimal places. For values from 0.10 to 10.0 ma

48、ss-%, report to two decimal places. For values 10.0 mass-% and higher, report to one decimal place. Notes and Precautions 1. Many waxy or viscous materials can be safely heated prior to transferring the desired amount into the flask. However, prolonged or overheating can often cause oxidative or the

49、rmal polymerization of asphaltene precursors. This will result in a higher insolubles content. 2. The importance of proper dispersion, the correct digestion time and continuous shaking cannot be overemphasized. Digestion time cannot be reduced by raising the bath temperature above 37C because samples tend to degrade if overheated, thereby increasing the asphaltene content. 3. Rinsing the funnel is best done by using a wash bottle containing warm pentane. When in doubt, use plenty of warm pentane. Do not allow the filter cake to become dry when rins