Determination of water content of crude oil by azeotropic distillation Karl Fischer coulometric titration

Abstract

The determination of water content in crude oil is important for oil transportation, refining, and trade. However, the sensitivity and accuracy of the conventional azeotropic distillation (AD) method are inadequate. Karl Fischer titration methods may give false high results because of the reducing sulfur compounds in crude oil. The present study developed an azeotropic distillation Karl Fischer coulometric titration (AD-KFCT) method which required a modified instrument and a new calibration procedure. The method was modified to decrease the interference caused by reducing sulfur compounds. A certified reference material for water content in liquid was used to determine the recovery of water mass achieved using the AD-KFCT method. The effect of the sample polarity on the method accuracy was assessed. The relative error and relative standard deviations of the water content in three crude oils containing known amounts of water were −7.5% to 2.9% and 0.4% to 6.0%, respectively. The interference by reducing sulfur compounds was studied. The crude oil containing 1-propanethiol was measured using a sulfur dioxide-free anolyte, and the amount of iodine consumed by the distilled 1-propanethiol was determined. The contribution of 1-propanethiol was then subtracted from the water content measured using the normal Karl Fischer reagent. Finally, the relative error of the modified water content in the crude oil samples containing 1-propanethiol was −4.4% to 0.7%. Therefore, the modified AD-KFCT method is accurate and convenient for crude oil.

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References

  1. 1.

    Margolis SA, Hagwood C. The determination of water in crude oil and transformer oil reference materials. Anal Bioanal Chem. 2003;376:260–9.

    CAS  Article  Google Scholar 

  2. 2.

    Less S, Hannisdal A, Bjorklund E, Sjoblom J. Electrostatic destabilization of water-in-crude oil emulsions: application to a real case and evaluation of the Aibel VIEC technology. Fuel. 2008;87(12):2572–81.

    CAS  Article  Google Scholar 

  3. 3.

    Veillet S, Tomao V, Visinoni F, Chemat F. New and rapid analytical procedure for water content determination: microwave accelerated Dean–Stark. Anal Chim Acta. 2008;632(2):203–7.

    Article  Google Scholar 

  4. 4.

    Margolis SA, Paulsen J, Park E. A coulometric method for determining substances that interfere with the measurement of water in oils and other chemicals by the Karl Fischer method. Anal Bioanal Chem. 2002;374:1274–81.

    CAS  Article  Google Scholar 

  5. 5.

    Frink LA, Armstrong DW. Determination of trace water content in petroleum and petroleum products. Anal Chem. 2016;88(16):8194–201.

    CAS  Article  Google Scholar 

  6. 6.

    Chang J, Chen J, Li R, Liu Y, Wang C. Electric dehydration experiment for offshore crude oil emulsions by using high frequency/high voltage AC electric field. Acta Petrol Sin (Pet Process Section). 2012;28(5):844–50.

    CAS  Google Scholar 

  7. 7.

    Doughty DA. Determination of water in oil emulsions by a microwave resonance procedure. Anal Chem. 1977;49(6):690–4.

    CAS  Article  Google Scholar 

  8. 8.

    American Society for Testing and Materials. Standard test method for water and sediment in crude oil by the centrifuge method (ASTM D4007–11). 2011. https://www.astm.org/Standards/D4007.htm. Accessed 31 Mar 2020.

  9. 9.

    Chang L, Qu Y. Weak signal detection of the crude oil moisture content by electromagnetic conductance method. Appl Mech Mater. 2013;303-306:819–22.

    Article  Google Scholar 

  10. 10.

    Song Y, Zhan HL, Zhao K, Miao XY, Lu ZQ, Bao RM, et al. Simultaneous characterization of water content and distribution in high-water-cut crude oil. Energy Fuel. 2016;30(5):3929–33.

    CAS  Article  Google Scholar 

  11. 11.

    Allsopp K, Wright I, Lastockin D, Mirotchnik K, Kantzas A. Determination of oil and water compositions of oil/water emulsions using low field NMR relaxometry. J Can Petrol Technol. 2001;40(7):58–61.

    CAS  Google Scholar 

  12. 12.

    Dean EW, Stark DD. A convenient method for the determination of water in petroleum and other organic emulsions. Ind Eng Chem. 1920;12(5):486–90.

    CAS  Article  Google Scholar 

  13. 13.

    Smets K, Adriaensens P, Vandewijingaarden J, Stals M, Cornelissen T, Schreurs S, et al. Water content of pyrolysis oil: comparison between Karl Fischer titration, GC/MS-corrected azeotropic distillation and 1H NMR spectroscopy. J Anal Appl Pyrol. 2011;90(2):100–5.

    CAS  Article  Google Scholar 

  14. 14.

    Kopyl’tsova AB, Tarasov BP, Bumblebee DN. Hygrometry of oil and products. Part 1. The distillation method: familiar and unfamiliar. Prod Qual Contr. 2014;2014(6):47–55.

    Google Scholar 

  15. 15.

    Kopyl’tsova AB, Tarasov BP, Root PV. Hygrometry of oil and products. Part 2. Coulometric Karl Fischer method: problems of application. Prod Qual Contr. 2014;2014(7):49–54.

    Google Scholar 

  16. 16.

    Sherman F, Kuselman I. Stoichiometry and chemical metrology: Karl Fischer reaction. Accred Qual Assur. 1999;4:230–4.

    CAS  Article  Google Scholar 

  17. 17.

    International Organization for Standardization. Crude petroleum – Determination of water — Coulometric Karl Fischer titration method (ISO 10337:1997). 1997. https://www.iso.org/standard/18388.html. Accessed 31 Mar 2020.

  18. 18.

    International Organization for Standardization. Determination of water – Karl Fischer method (General method) (ISO 760:1978). 1978. https://www.iso.org/standard/5037.html. Accessed 31 Mar 2020.

  19. 19.

    Dantan N, Frenzel W, Küppers S. Determination of water traces in various organic solvents using Karl Fischer method under FIA conditions. Talanta. 2000;52(1):101–9.

    CAS  Article  Google Scholar 

  20. 20.

    Nordmark U, Cedergren A. Conditions for accurate Karl Fischer coulometry using diaphragm free cells. Anal Chem. 2000;72(1):172–9.

    CAS  Article  Google Scholar 

  21. 21.

    Scholz E. Karl Fischer titration: determination of water chemical laboratory practice. New York: Springer; 1984.

    Google Scholar 

  22. 22.

    Roberts FM, Levin H. Determination of small amounts of water. Anal Chem. 1949;21(12):1553–5.

    CAS  Article  Google Scholar 

  23. 23.

    Archer EE, Hilton J. The determination of small amounts of water in gases using Karl Fischer reagent. Analyst. 1974;99:547–50.

    CAS  Article  Google Scholar 

  24. 24.

    Jalbert J, Gilbert R, Tétreault P. Determination of the analytical performance of a headspace capillary gas chromatographic technique and Karl Fischer coulometric titration by system calibration using oil samples containing known amounts of moisture. Anal Chem. 1999;71(15):3283–91.

    CAS  Article  Google Scholar 

  25. 25.

    Margolis SA, Mele T. Systematic bias in the measurement of water in oils by tubular oven evaporation and azeotropic distillation. Anal Chem. 2001;73(20):4787–92.

    CAS  Article  Google Scholar 

  26. 26.

    Larsson W, Jalbert J, Gilbert R, Cedergren A. Efficiency of methods for Karl Fischer determination of water in oils based on oven evaporation and azeotropic distillation. Anal Chem. 2003;75(6):1227–32.

    CAS  Article  Google Scholar 

  27. 27.

    Dean JA. Lange’s handbook of chemistry. New York: McGraw-Hill Inc.; 1998.

    Google Scholar 

  28. 28.

    International Organization for Standardization. Natural gas – Determination of water by the Karl Fischer method – Part 3: Coulometric procedure (ISO 10101-3:1993). 1993. https://www.iso.org/standard/18077.html. Accessed 31 Mar 2020.

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Acknowledgments

This study was supported by the National Quality Infrastructure Program of China (grant no. 2017YFF0205300) and the Ability Promotion Program of the National Institute of Metrology of China (grant no. 31-ANL1814).

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Correspondence to Haifeng Wang.

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Zhen, Z., Wang, H., Yue, Y. et al. Determination of water content of crude oil by azeotropic distillation Karl Fischer coulometric titration. Anal Bioanal Chem 412, 4639–4645 (2020). https://doi.org/10.1007/s00216-020-02714-5

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Keywords

  • Water content
  • Crude oil
  • Azeotropic distillation
  • Karl Fischer coulometric titration