UOP 212-2005 HYDROGEN SULFIDE MERCAPTAN SULFUR AND CARBONYL SULFIDE IN HYDROCARBON GASES BY POTENTIOMETRIC TITRATION.pdf

1、 uop 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 PRES

2、CRIBED 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 1959, 1968, 1972, 1977, 2003, 2004

3、, 2005 UOP LLC. 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 se

4、rviceastm.org, 610.832.9555 FAX, or 610.832.9585 PHONE. HYDROGEN SULFIDE, MERCAPTAN SULFUR, AND CARBONYL SULFIDE IN HYDROCARBON GASES BY POTENTIOMETRIC TITRATION UOP Method 212-05 SCOPE This method is for determining hydrogen sulfide (H2S), mercaptan sulfur (RSH) and carbonyl sulfide (COS) in gaseou

5、s hydrocarbons and in typical liquefied petroleum gas (LPG) consisting of C3and/or C4hydrocarbons. Also covered is the determination of mercaptan sulfur in LPG which may contain a wide range of hydrocarbon types ranging from ethane to such gasoline boiling range hydrocarbons as pentane and hexane. E

6、ach sulfur type can be determined from less than 1 to several thousand mass-ppm sulfur (less than 0.1 to several thousand grains per 100 cu ft). REFERENCES ASTM Method D 1070, “Relative Density of Gaseous Fuels,” www.astm.org ASTM Method D 6667, “Total Volatile Sulfur in Gaseous Hydrocarbons and Liq

7、uefied Petroleum Gases by Ultraviolet Fluorescence,” www.astm.org Bruss, D.B., Wyld, G.E.A., and Peters, E.D., Anal. Chem., 29, 807 (1957) Handbook of Chemistry and Physics; Lykken, L., and Tuemmler, F.D., Ind. Eng. Chem., Anal. Ed., 14, 67 (1942) Tamele, M.W., Ryland, L.B., and Irvine, V.C., Ind.

8、Eng. Chem., Anal. Ed., 13, 618 (1941) UOP Method 163, “Hydrogen Sulfide and Mercaptan Sulfur in Liquid Hydrocarbons,” www.astm.org UOP Method 516, “Sampling and Handling Gasolines, Distillate Fuels, and of C3-C4Fractions,” www.astm.org UOP Method 948, “Relative Density of Gas Mixtures by Calculation

9、 from Composition,” www.astm.org UOP Method 999, “Precision Statements in UOP Methods,” www.astm.org Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement with Monique Tyree (IHS); Mon Feb 7 16:52:52 EST 20052 of 25 212-05 OUTLINE OF METHOD The sample, taken eith

10、er from a sample cylinder or directly from a refinery stream according to the procedures described in UOP Method 516, is scrubbed first through a potassium hydroxide solution and then through a monoethanolamine solution. The potassium hydroxide solution contains chelating agents which inhibits the o

11、xidation of sulfur compounds by chelating heavy metals. A potentiometric titration of the absorbed hydrogen sulfide and mercaptan sulfur in the potassium hydroxide solution follows, using either an aqueous or an alcoholic silver nitrate titrant. The monoethanolamine solution, which contains the abso

12、rbed carbonyl sulfide is titrated potentiometrically with alcoholic silver nitrate in an acidic titration solvent. The electrode system for both titrations is a silver/silver sulfide electrode with a glass reference electrode. The concentration of each analyzed component is calculated from the titra

13、tion curve. Either an automatic (preferred) or a manually-operated titrator may be used. APPARATUS References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used if equivalent performance can be obtained. In addition to the apparatus listed

14、below, all of the sampling-related apparatus specified in UOP Method 516 for C3-C4fractions is also required for this method. Balance, capable of weighing 5 kg to the nearest 0.5 g Balance, readability 0.1-mg Barometer, Fisher Scientific, Cat. No. 02-406 Beakers, electrolytic, 250-mL, Brinkmann Inst

15、ruments, Cat. No. 020212209, two or more required Beaker, stainless steel, 4000-mL, Fisher Scientific, Cat. No. 02-583G. Drill a hole in the bottom to fit the selected neoprene stopper. Cleaning pad, synthetic, mildly abrasive, Scotch-Brite, Runco Office Supply, Cat. No. MMM-96 Electrode, combinatio

16、n silver/glass titrode, Brinkmann Instruments, Cat. No. 020948507. The electrode should be dedicated to sulfur analysis. Flasks, volumetric, Class A, 250-, 500-, and 1000-mL, Fisher Scientific, Cat. Nos. 10-210-5E, -5F, and -5G, respectively Flask, volumetric, Class A, amber, for light sensitive mat

17、erials, 100-mL, Fisher Scientific, Cat. No. 10-229C Funnel, separatory, 250-mL, Fisher Scientific, Cat. No. 10-437-5C Gas washing bottle, 125-mL. The type fitted with sintered glass disk of coarse porosity is suitable and can be obtained commercially, Reliance Glass, Cat. No. LG-3761-100, or, Fisher

18、 Scientific, Cat. No. 03-040A. Because light is the most serious factor affecting recovery of carbonyl sulfide, completely mask the gas washing bottle with black tape. In order to view the bubbling, a vertical slit, 2-3 mm wide, may be cut in the tape, which can taped over except when needed. Gas wa

19、shing bottle, 250-mL, Reliance Glass, Cat. No. LG-3690-110 Gas washing bottles, 250-mL. The type fitted with a sintered glass gas-distribution plate of coarse porosity is suitable and this type can be obtained commercially, Reliance Glass, Cat. No. LG-Copyright by ASTM Intl (all rights reserved);Rep

20、roduction authorized per License Agreement with Monique Tyree (IHS); Mon Feb 7 16:52:52 EST 20053 of 25 212-05 3762-102, or Fisher Scientific, Cat. No. 03-040B, two required. The maximum gas flow rate for this type of gas washing bottle is about 30 L/hr (1 cu ft/hr). If no COS scrubber is connected

21、downstream of the caustic scrubbers, an alternative gas washing bottle, suitable for a higher flow rate, may be used. This type is fitted with a perforated disk gas distributor (see Figure 1), and is available on special order from Reliance Glass. The rate with this distributor can be as high as 90

22、L/hr (3 cu ft/hr), provided that no COS scrubber is connected downstream from the caustic scrubber. The scrubbing rate for the COS scrubber must not exceed 30 L/hr. Gauge, pressure, stainless steel, 0 to 2800 kPa gauge (0 to 400 psig) range, Matheson Tri-Gas, Cat. No. 63-2242, with adapter to fit th

23、e specific sample cylinders used Graduated cylinders, 5-, 100-, and 1000-mL, Fisher Scientific, Cat. No. 08-550A, -550E, and -550H, respectively Laboratory expansion valve, Swagelok Type SS-3NRS4 (regulating stem 316 stainless steel valve and fittings), Swagelok. Wrap the valve with electrical heati

24、ng tape and provide a variable transformer to control the temperature of the tape. (See Figure 2 for laboratory expansion valve apparatus arrangement.) To ensure that the valve provides a smooth, regular flow without any blockages, it must be cleaned regularly, by rinsing with water,. Additional mai

25、ntenance requires either a rebuild kit, returning to the manufacturer for repair, or replacement. Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement with Monique Tyree (IHS); Mon Feb 7 16:52:52 EST 20054 of 25 212-05 Pipets, Class A, 1-, 2-, 3-, 5-, 10-, 15-,

26、25-, and 50-mL, Fisher Scientific, Cat. Nos. 13-650-2B, -2C, -2D, -2F, -2L, -2M, -2P, and -2S, respectively Pipet, Mohr, 5-mL, Fisher Scientific, Cat. No. 13-665K Pipet filler, Fisher Scientific, Cat. No. 03-692-35 Refinery expansion valve, Swagelok Type SS-3NRS4 (regulating stem 316 stainless steel

27、 valve and fittings), Swagelok. Since the use of electrically-heated expansion valves is not permitted in refineries, use a hot water heating system for vaporizing an on-stream sample. (See Figure 3 for refinery expansion valve apparatus arrangement.) To ensure that the valve provides a smooth, regu

28、lar flow without any blockages, it must be cleaned regularly, by rinsing with water. Additional maintenance requires either a rebuild kit, returning to the manufacturer for repair, or replacement. Regulator, nitrogen, two-stage, high-purity, delivery pressure range 15-200 kPa (2-30 psi), Matheson Tr

29、i-Gas, Model 3121-580 Stoppers, neoprene, sizes to fit specific apparatus. Fisher Scientific, Cat. No. 14-141*. Bore holes as necessary using Boring Machine, Fisher Scientific, Cat. No. 07-855. *Select sizes to fit containers. Stopwatch, Fisher Scientific, Cat. No. 14-648-3 Tape, heating, electrical

30、, Fisher Scientific, Cat. No. 11-463-54A Tape, polyethylene, black, Fisher Scientific, Cat. No. 11-866-2 Thermometer or thermocouple, capable of reading heated expansion valve temperature of 38-43C (100-110F) Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement

31、with Monique Tyree (IHS); Mon Feb 7 16:52:52 EST 20055 of 25 212-05 Titrator, potentiometric, recording, 2000-mV range, 1-mV resolution, capable of reducing the titration rate to a minimum in the vicinity of the endpoint, with dispenser having a volume readout of 0.00 - 99.99 mL, 0.0001 of the buret

32、 volume resolution, Metrohm Model 836 Titrando system with optional sample changer, and 20-mL buret, Brinkmann Instruments Transformer, variable, Fisher Scientific, Cat. No. 11-472-76 (for 120V) Tubing, rubber, 3/16” ID, Fisher Scientific, Cat. No. 14-167C Tubing, stainless steel, ” OD, Alltech Asso

33、ciates, Cat. No. 30306ST Wash bottle, for 2-propanol, Fisher Scientific, Cat. No. 03-409-20D Wet test gas meter or calibrated gas receiver, 225 L/hr capacity, Meters Reproduction authorized per License Agreement with Monique Tyree (IHS); Mon Feb 7 16:52:52 EST 20056 of 25 212-05 Acid titration solve

34、nt. Dissolve 2.7 g of sodium acetate trihydrate in 20 mL of water and 975 mL of anhydrous ethyl alcohol. Add 4.6 mL of glacial acetic acid to the solution. Purge the solution with nitrogen for 10 to 15 minutes prior to use to remove dissolved oxygen. Ammonium hydroxide, concentrated, Certified ACS P

35、lus, Fisher Scientific, Cat. No. A669-212 Cadmium chloride, Certified ACS, Fisher Scientific, Cat. No. C10-500 Cadmium chloride solution. Dissolve 100 g of cadmium chloride in 500 mL of water. Add 10 mL of concentrated hydrochloric acid and make up to a final volume of 1 L with water. Purge with nit

36、rogen for 10 to 15 minutes before using. Chelating solution, a solution of chelating agents found effective in reducing the deterioration of sulfides and mercaptides in caustic solutions. The recommended usage is 2 mL/100 mL of caustic solution. This chelating solution is made up from the constituen

37、t chemicals: Diethylenetriamine pentaacetic acid, sodium salt (Na5DTPA), Acros Organics, Fisher Scientific, Cat. No. 40729-0010 (40% aqueous solution) Diethylenetriamine pentaacetic acid, sodium salt, 20 mass-% solution. Dilute diethylene-triamine pentaacetic acid, sodium salt, 40% aqueous solution,

38、 with water to make a 20 mass-% solution. N-(2-hydroxyethyl) ethylenediaminetriacetic acid, sodium salt, (Na3HODTA), Aldrich, Cat. No. 16,153-5, or Acros Organics, Fisher Scientific, Cat. No. 34870-0010 N-(2-hydroxyethyl) ethylenediaminetriacetic acid, sodium salt, 20 mass-% solution. Dissolve N-(2-

39、hydroxyethyl) ethylenediaminetriacetic acid, sodium salt, in water to make a 20 mass-% solution. Ethylenediaminetetraacetic acid, sodium salt (Na4EDTA), Aldrich Chemical, Cat. No. E2,629-0, or, Acros Organics, Fisher Scientific, Cat. No. 14786-5000 N,N-bis(2-hydroxyethyl)glycine (Bicine), Aldrich Ch

40、emical, Cat. No. 16,379-1, or, Acros Organics, Fisher Scientific, Cat. No. 17265-1000 Mix 1:1 by weight ethylenediaminetetraacetic acid, sodium salt, and N,N-bis(2-hydroxyethyl) glycine. Dissolve in water to make a 20 mass-% solution. Mix equal volumes of each of the three 20 mass-% solutions to mak

41、e the final chelating solutiuon. Detergent, LiquiNox, Fisher Scientific, Cat. No. 04-322-15B Ethyl alcohol, anhydrous, spectro grade, Acros Organics, Cat. No. 22409-5000 Hydrochloric acid, concentrated, Certified ACS Plus, Fisher Scientific, Cat. No. A144S-500 Lead acetate test paper, Fisher Scienti

42、fic, Cat. No. 14-862 Leak test solution, soap solution, Snoop, Swagelok, Cat. No. MS-SNOOP-8OZ Monoethanolamine (ethanolamine), 99%, Acros Organics, Cat. No. 14958-0025 Monoethanolamine, 5 vol-% solution in ethyl alcohol. Prepare by pipetting 5 mL of monoethanolamine into an amber 100-mL volumetric

43、flask. Fill to the mark with ethyl alcohol. Store in a dark place. Purge with nitrogen for 10 to 15 minutes before using. Discard after one day. Nitrogen, high purity, 99.99% Copyright by ASTM Intl (all rights reserved);Reproduction authorized per License Agreement with Monique Tyree (IHS); Mon Feb

44、7 16:52:52 EST 20057 of 25 212-05 Potassium hydroxide, 50 w/v-% solution, Fisher Scientific, Cat. No. LC19260-2 Potassium hydroxide, 40 w/v-% solution. Prepare by diluting four parts of 50 w/v-% solution with one part of water. Purge with nitrogen for 10 to 15 minutes before using. Use only for samp

45、les high in hydrogen sulfide. Potassium hydroxide, 10 w/v-% solution, Fisher Scientific, Cat. No. LC19200-2 Purge with nitrogen for 10 to 15 minutes before using. 2-Propanol, Certified ACS grade, Fisher Scientific, Cat. No. A416-4. Purge with nitrogen for 10 to 15 minutes before using. Silver nitrat

46、e, 0.1-M solution, standardized at 25C against NIST potassium chloride, lot analysis supplied, Fisher Scientific, Cat. No. SS72-4 Silver nitrate, 0.01-M standard aqueous solution. Prepare by pipetting 50 mL of the 0.1-M solution into a 500-mL volumetric flask. Dilute to the mark with water, cap and

47、invert several times to mix thoroughly. The molarity of this solution is one-tenth the molarity of the purchased, nominally 0.1-M solution. Silver nitrate, 0.01-M standard alcoholic solution. Prepare by pipetting 50 mL of the 0.1-M solution into a 500-mL volumetric flask. Dilute to the mark with 2-p

48、ropanol, cap and invert several times to mix thoroughly. The molarity of this solution is one-tenth the molarity of the purchased, nominally 0.1-M solution. Sodium acetate trihydrate, Certified ACS grade, Fisher Scientific, Cat. No. S209-500 Sodium carbonate, 5 w/v-% solution, Fisher Scientific, Cat

49、. No. LC22970-2. Purge with nitrogen before using. Sodium hydroxide, 20 w/v-% solution, Fisher Scientific, Cat. No. LC24090-2 Sodium sulfide, 3 w/v-% solution, Fisher Scientific, Cat. No. LC24920-2 Wipers, Kimwipes, Ex-L, Fisher Scientific, Cat. No. 06-666A SAMPLING Refer to UOP Method 516, Sampling and Handling of Gasolines, Distillate Fuels, and C3-C4Fractions, for the required sample cylinders (Silcosteel recommended), their preparation and cleaning, and sampling procedures for C3-C4fractions. SCRUBBING OF GASES If analysis of COS is not required, the COS scr