Corrosivity of Fluids as a Function of the Distillate Cut: Application of an Advanced Distillation Curve Method

Recently, we reported a method and apparatus for the advanced measurement of distillation curves. The new method allows for increased precision in the measurement of distillation curves as well as a composition-explicit channel of data. Herein, we report a further extension of this method, one which provides the capability to assess corrosivity and quantitate corrosive impurities (such as acidic sulfur species commonly found in fuel feedstocks) as a function of the distillate fraction. To demonstrate the new metrology, we examined mixtures of n-decane and n-tetradecane with dissolved H2S. At each of 11 predetermined distillate volume fractions, the corrosivity was measured with the copper strip corrosion test (CSCT) and the sulfur concentration was measured by gas chromatography with sulfur chemiluminescence detection. Significantly, we were able to quantitatively correlate the distillation temperature of the fluid with both the sulfur concentration and the results of a CSCT for samples that had initial s...