1、Designation: D1157 91 (Reapproved 2014)Standard Test Method forTotal Inhibitor Content (TBC) of Light Hydrocarbons1,2This standard is issued under the fixed designation D1157; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of totalp-tertiary-butylcatechol inhibitor added to polymerization andr
3、ecycle grades of butadiene or to other C4hydrocarbonmixtures containing no phenolic material other than catechol orno oxidized phenolic material other than that derived fromoxidation of catechol. In general, all phenols and their quinoneoxidation products are included in the calculated catecholconte
4、nt. Small amounts of polymer do not interfere. This testmethod is applicable over the range of TBC from 50 to500 mgkg.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesa
5、fety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D1265 Practice for Sampling Li
6、quefied Petroleum (LP)Gases, Manual Method3. Summary of Test Method3.1 The catechol is separated from the butadiene by evapo-ration. The residue is dissolved in water and an excess of ferricchloride is added. The intensity of the yellow-colored complexis compared in a photoelectric colorimeter with
7、that producedby known concentrations of the catechol.4. Significance and Use4.1 p-tertiary-butylcatechol is commonly added to commer-cial butadiene in amounts of 50 to 250 mg/kg as an oxidationinhibitor. This test method is suitable for use by both producersand users of butadiene within the limitati
8、ons described inSection 1.5. Apparatus5.1 PhotometerA sensitive photoelectric photometer ca-pable of producing light of narrow spectral range that ispredominantly blue (425 nm).5.2 Graduates, 100-mL.5.3 Volumetric Flasks, 100-mL; or stoppered graduatedmixing cylinder, 100-mL.5.4 Erlenmeyer Flasks, 2
9、50-mL.5.5 Funnels, 75-mm diameter.5.6 Pipet, 5-mL.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Soci
10、ety,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterReferences to water shall be under-stood to mean distilled wat
11、er.6.3 Ferric Chloride, Standard Solution Dissolve 20.0 g offerric chloride (FeCl36H2O) in ethanol (95 %). Add 9.2 mL ofHCl (sp gr 1.19), and then dilute with ethanol (95 %) to1000 mL in a volumetric flask.6.4 p-Tertiary-Butylcatechol, Standard(WarningPotentially hazardous. May cause skin irritation
12、 or burns; can1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility ofSubcommittee D02.D0.04 on C4 Hydrocarbons.Current edition approved May 1, 2014. Published July 2014. Originally approvedin 1951. Last p
13、revious edition approved in 2009 as D1157 91 (2009). DOI:10.1520/D1157-91R14.2This test method was derived from the method developed and cooperativelytested by the Butadiene Producers Committee on Specifications and Methods ofAnalysis of the Office of Rubber Reserve, which appears in the ButadieneLa
14、boratory Manual as Method 2.1.9.1.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Reagent Chemicals, America
15、n Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U
16、.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1be absorbed through the skin. May be harmful or fatal ifswallowed. Avoid contact with eyes; may burn and impairvision. May be harm
17、ful to respiratory system. May producequinones and flammable butylenes on decomposition. Use withadequate ventilation. Store in flammable liquids storage area.)Dissolve 0.63 g of p-tertiary-butylcatechol (95 % minimumpurity) in 10 mL of ethanol (95 %) and dilute with water to100 mL in a volumetric f
18、lask. When used in place of 100 mL(63 g) of sample, consider 1.00 mL of this solution to beequivalent to 100 ppm of catechol. This solution is not stableand should be prepared as needed.7. Sampling7.1 Supply samples to the laboratory in high-pressuresample cylinders. Use the procedures described in
19、PracticeD1265 or similar methods.8. Calibration and Standardization8.1 Preparation of Standard SolutionsPrepare a standard-ization curve showing the relation between the absorbance andthe catechol content as follows: Make up solutions of knowncatechol content by pipetting 0, 1, 2, 3, 4, and 5-mLport
20、ions ofthe standard catechol solution (1.00 mL = 100 mg/kg) intoseparate 100-mL volumetric flasks, or stoppered, graduatedmixing cylinders. Then add enough water to each flask orcylinder to make a total volume of approximately 90 mL. Add5.0 6 0.1 mL of standard FeCl3solution, bring the totalvolume t
21、o 100 mL and mix well.8.2 Measurement of StandardsFive to fifteen minutesafter the addition of the FeCl3reagent, measure the absorbanceof the solution by means of a photoelectric photometer, usingwater as a reference standard and using light that is predomi-nantly blue (425 nm).8.3 Preparation of Ca
22、libration CurveSubtract the readingobtained for the zero catechol standard from each of the abovereadings, using the same volumes of FeCl3solution and waterand observing the same time limits. Record the difference asthe respective “net” absorbance. Assuming 1.0 mL of thestandard catechol solution to
23、 be equal to 100 mg/kg of catecholin the butadiene, plot the net absorbance against the amount ofadded catechol in mg/kg.NOTE 1While this test method of plotting a curve is the recognizedmethod, it has been found that the blank or zero reading using the FeCl3reagent described in 6.3 does not change,
24、 thus enabling, for control work,the plotting of a curve that can be read directly.9. Procedure9.1 Preparation of SampleMeasure 100 6 1 mL of liquidsample (WarningExtremely flammable gas under pressure.May form explosive peroxides upon exposure to air. Harmful ifinhaled. Irritating to eyes, skin, an
25、d mucous membranes.) intoa graduate that has been cooled to below 20C. Pour thesample into a 250-mL Erlenmeyer flask and allow the liquid toevaporate at room temperature behind a shield in a well-ventilated hood. A steam bath may be used to complete theevaporation. Add 30 mL of water to the flask, s
26、topper, shake,and filter through a rapid, hardened, low-ash paper that haspreviously been moistened. Repeat with two more 30-mLportions of water. Combine all filtrates, add from a pipet5.0 6 0.1 mLof standard FeCl3solution, dilute to 100 mL, andmix well.9.2 Measurement of SampleAfter the addition of
27、 theFeCl3reagent, allow the solution to stand for from 5 to 15 min,then measure the absorbance of the solution by means of aphotoelectric photometer, using water as a reference standard.NOTE 2Take care to have the comparison tubes clean and free fromfingerprints and spilled solution. From time to ti
28、me, the two tubes shouldbe checked against each other with blank solution in both.9.3 Measurement of SampleMake a “blank”determination, following the same procedure, but omitting theaddition of the sample. Subtract the absorbance of the “blank”from that of the sample and record the difference as the
29、 “net”absorbance.NOTE 3A “blank” determination need be made only when first usinga bottle of freshly prepared FeCl3solution to ascertain that the reagent wasmade properly.10. Calculation10.1 By use of the calibration curve, convert the netabsorbance obtained to milligrams per kilograms of p-tertiary
30、-butylcatechol.11. Precision and Bias11.1 PrecisionThe precision of this test method as ob-tained by statistical examination of interlaboratory test resultsis as follows:11.2 RepeatabilityThe difference between successive testresults obtained by the same operator with the same apparatusunder constan
31、t operating conditions on identical test materialwould, in the long run, in the normal and correct operation ofthe test method exceed the following values only one case intwenty:p-tertiary butylcatecholrange, mg/kgRepeatability50 to 500 1011.3 ReproducibilityThe difference between two singleand inde
32、pendent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod exceed the following values only one case in twenty:p-tertiary butylcatecholrange, mg/kgReproducibility50 to 500
33、2011.4 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod for measuring TBC in hydrocarbons, no statement onbias is being made.12. Keywords12.1 light hydrocarbons; oxidation inhibitor; p-tertiary bu-tylcatechol; photometerD1157 91
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