DETERMINATION OF WATER CONTENT OF CRUDE OIL BY AZEOTROPIC DISTILLATION-KARL FISCHER COULOMETRIC TITRATION
Water content of crude oil is of great importance for the oil extraction,dehydration and refining process as well as the oil trade,so the accurate measurement of water content of crude oil is crucial.The azeotropic distillation method for water content is time consuming and insensitive.For Karl Fischer coulometry,the electrode is prone to be polluted by crude oil.Furthermore,the reducing compound containing sulfur in crude oil is readily oxidized by iodine in Karl Fischer reagents which results the positive error of water content.A home-made distillation apparatus has been developed to introduce the azeotropic mixture of water and toluene in analyte into the Karl Fischer coulometric titration cell for the measurement of water content.The limitation of detection(LOD)of this method is only 11.4μg.The recovery at varied water mass was determined by using the certified reference material for water content.Three kinds of crude oils were measured by this method.Their water contents and relative standard deviation are 1270 mg/kg(4.3%),119.3 mg/kg(13.6%)and 1421 mg/kg(8.2%),respectively.These results basically agreed with those by Karl Fischer volumetric method using the direct addition of analyte.Additionally,the repeatability of this new method is much better than the traditional azeotropic distillation and is slightly worse than the Karl Fischer volumetry.This new method has a well potential for crude oil due to its speediness,sensitivity and non-contact between analyte and Karl Fischer reagents.
crude oil water content azeotropic distillation Karl Fischer coulometric titration
C.Y.PEI H.F.WANG Q.YE X.P.SONG Z.Y.LI K.MA
Beijing University of Technology 100022,China National institute of metrology of China,Beijing 100013,China
国际会议
国际测量技术联合会(IMEKO)2017年国际测量技术研讨会
杭州
英文
7-11
2017-09-04（万方平台首次上网日期，不代表论文的发表时间）