In Situ Chemical Imaging of Asphaltene Precipitation from Crude Oil Induced by n-Heptane

摘要

Crude oil fouling in heat exchangers is one of the most challenging problems in a petroleum refinery. The fundamentals of the complex fouling process are not fully understood, which leads to inefficient prevention of deposition in heat exchangers. From an industrial point of view, it is difficult to predict the precipitation of some constituents from crude oil under particular conditions and to create precautionary measures. ATR-FTIR spectroscopic imaging is a powerful tool for providing visualization and chemical analysis when applied to study a range of dynamic systems and samples. Here, we report an ATR-FTIR spectroscopic imaging approach for in situ visualization and chemical characterization of the formation of deposits from crude oil. To demonstrate ATR-FTIR spectroscopic imaging capabilities, experiments on n-heptane induced precipitation from Tatarstan crude oil have been performed. The dynamics of precipitation induced by n-heptane have been monitored starting from the formation of small particles on the measuring surface of the ATR crystal followed by their growth and aggregation. The deposits formed have been chemically characterized using extracted ATR-FTIR spectra. Asphaltenes have been identified as the main components of the observed deposits. This study has demonstrated the feasibility and potential applications of ATR-FTIR spectroscopic imaging to understand how the molecular and chemical structures of the deposits relate to the components of the crude oil. This information about asphaltene deposits will provide new insight and understanding about the fouling process.