25th International Meeting on Organic Geochemistry IMOG 2011

P-012
Heteroatom-containing compounds in maltenes and asphaltenes
separated from a sequence of fort mcmurray crude oils detected
by negative-ion ESI FT-ICR MS
Yinhua Pan, Yuhong Liao
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China (corresponding
author:liaoyh@gig.ac.cn)
The application of Fourier transform ion cyclotron
resonance mass spectrometry (FT-ICR MS), which
has ultra-high available broadband mass resolution,
mass resolving power and mass accuracy, makes it
possible to identify thousands of heteroatomcontaining
compounds in crude oils at molecular level
with higher resolution. In this research, electrospray
ionization ESI FT-ICR-MS was used to study a
sequence of 5 crude oils from one oil column of Fort
McMurray (FM) of Canada, which are of different
depth (280.75-310.00m). Separated maltenes and
asphaltenes were analyzed by ESI FT-ICR MS,
respectively (Fig. 1).
Fig. 1. Negative-ion ESI FT-ICR mass spectrum of
maltenes and asphaltenes separated from one FM
crude oil.
The results show that maltenes fraction in these crude
oils contains N1, N1O1, N1O2, N1S1, O1, O1S1, O2,
O2S1, O3, O3S1, O4, O4S1 and S1 heteroatom classes,
and 15-48 carbon atoms with double-bond equivalent
(DBE) values of 1-19 (Fig. 2). Asphaltenes fraction
contains more heteroatom classes of N1, N2, N1O1,
N1O2, N1O3, N1S1, O1, O1S1, O1S2, O2, O2S1, O2S2, O3,
O3S1, O3S2, O4, O4S1, O4S2, O5, O5S1, O5S2 and O6
with highly sulfur-containing compounds and DBE of
0-23 (Fig. 3). Heteroatom-containing compounds in
asphaltenes show a longer broadband up to 1000
(m/z) than in maltenes. The distribution patterns of N1
and O2 classes as the major species in maltenes and
asphaltenes. Specially, asphaltenes contain acidic
classes rich in OxSy (x:2-5; y:0-2) compounds. Sulfur
species are of both non-polar (thiophene-like) and
polar (sulfoxide) classes. Sulfur species are usually
the most abundant of the heteroatom-containing
species and are broadly distributed across the carbon
number range of petroleum fractions. Surfurcontaining
compounds make higher proportion in
asphaltenes than in maltenes. There is no obvious
trend in compositional variation with depth among FM
crude oils in maltenes while there is obvious trend in
asphaltenes. In asphaltenes, species containing the
same number of oxygen atoms obey the same trend.
For example, O2, O2S1 and O2S2 keep a raising trend.
While the trends of both O2Sx and O4Sx (x:0-2)
classes of the FM crude oils are different. It may be
due to the differences in biodegradation.
Fig. 2. Relative abundance of heteroatom class
species in maltenes.
Fig. 3. Relative abundance of heteroatom class
species in asphaltenes.
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