화학공학소재연구정보센터
Energy & Fuels, Vol.30, No.2, 915-923, 2016
Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Asphaltene Deposit Solubility Fractions: Comparison to Bulk Properties
In the present work, a field deposit, the solubility fractions, and heptane-precipitated asphaltenes from the crude oil were analyzed using atmospheric pressure photoionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). The main objective was to evaluate if the compositional distribution of the deposit closely match the bulk data as well as the effect of solubility fractionation in the molecular distribution using APPI. Analyses of the solubility fractions reveal a significantly larger number of assigned species than a similar analysis of the unfractionated field deposit. However, the increase of assigned species does not seem to provide more information in terms of the compositional distribution or average properties. The field deposit contains more components with low aromaticity as well as more oxygen containing species than the heptane asphaltenes. In contrast, heptane asphaltenes are enriched in N-containing species. Average values (H/C, density, and molecular weight) calculated for the solubility fractions match remarkably well the bulk values for the asphaltene fractions obtained from the deposit. In contrast, errors for the maltene fraction are much larger. This is the result of the preferential ionization of highly aromatic molecules, less abundant on maltenes than in the asphaltene fractions. These results indicate that APPI provides access to a broad range of molecules in asphaltenes that, collectively, can be used to describe bulk properties of the fraction.