Measuring Sulfur Content and Corrosivity of North American Petroleum with the Advanced Distillation Curve Method

Abstract

Petroleum is a complex fluid whose sulfur content varies considerably depending on its place of origin. Sour crude petroleum, which contains more than 0.5% sulfur by mass, often requires additional processing due to the potential for corrosion and catalyst poisoning during refining. Estimating or measuring the sulfur content of distillate fractions as a function of boiling temperature is an important step in petroleum refining. The advanced distillation curve (ADC) method was developed to provide a composition-explicit data channel for the measurement of thermophysical and chemical properties of complex fluids. We applied the ADC method to a composite sample of North American petroleum to characterize its boiling temperature, density, and composition as a function of distillate volume fraction. The compositions of light distillate fractions were used to estimate their densities and refractive indices based on critically evaluated thermodynamic data. The estimated densities of the distillate fractions are consistent with pycnometry data. The sulfur content, measured with a sulfur chemiluminescence detector, was found to be within the range predicted by an empirical model based on distillate boiling temperature and density. The corrosivity of various distillate cuts was tested with a modified copper strip corrosion test. Copper tarnishing was found to depend not only on the amount of sulfur present but also on the temperature at which the fraction is collected.