Characterization of Asphaltenes and Petroleum Using Benzenepolycarboxylic Acids (BPCAs) and Compound-Specific Stable Carbon Isotopes

Characterization of Asphaltenes and Petroleum Using Benzenepolycarboxylic Acids (BPCAs) and Compound-Specific Stable Carbon Isotopes

Asphaltenes

Gasoline

Mass spectrometry

Petroleum analysis

Aromatic compounds

Carbon

Physicochemical properties

Isotopes

Asphaltenes are unique molecules whose abundance and structure control physicochemical properties of petroleum. The structural appearance of asphaltenes (island versus archipelago architecture) is dependent upon the sample type and petroleum source, but distinguishing between the two architectures remains analytically challenging. Here, we present the application of the benzenepolycarboxylic acid (BPCA) molecular marker method to characterize the condensed aromatic core (ConAC) of asphaltenes. This thermochemolytic technique converts ConAC moieties to benzenehexacarboxylic (B6CA) and benzenepentacarboxylic (B5CA) acids, which are quantified chromatographically and used to estimate the quantity of ConAC in petrogenic samples. Sequential compound-specific isotope analysis (CSIA) with stable carbon isotopes (13C) of BPCA markers can provide an additional dimension of characterization relative to carbon source and processing. We analyzed the heavy Maya sour and light Marlin platform (MPCO) crude oils and their respective asphaltene fractions. Quantitative BPCA analysis revealed that Maya sour asphaltenes contained higher quantities of larger ConAC relative to MPCO asphaltenes. CSIA of individual BPCA markers showed that Maya sour asphaltenes are 13C-depleted relative to MPCO asphaltenes, even though bulk organic 13C values were similar among sample types. Taken together, the results of quantitative and CSIA BPCA analyses suggest island-dominant architecture for Maya asphaltenes and archipelago-dominant architecture for MPCO asphaltenes. Therefore, BPCA quantification and BPCA-specific 13C analysis may be a useful approach characterizing petrogenic samples as well as differentiating between structural architectures of condensed aromatic cores in asphaltenes. This article is in tribute to Dr. Alan G. Marshall for his numerous contributions to the scientific developments in analytical chemistry and environmental science, specifically the co-invention of the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) technique and his work toward the deconvolution of complex matrices, such as asphaltenes and petroleum.

18135-18145

22

35

Energy and Fuels

2021

Goranov, Aleksandar I.

Schaller, Morgan F.

Long, Jonathan A.

Podgorski, David C.

Wagner, Sasha

journalArticle

8870624

10.1021/acs.energyfuels.1c02374