Heavy crude oil samples, fractionated according to the
saturates, aromatics, resins, and asphaltenes (SARA) fractionation
method, were analyzed by Fourier transform ion cyclotron resonance
mass spectrometry (FT-ICR MS) equipped with atmospheric pressure photoionization
(APPI). SARA fractionation separates the crude oil into four main
classes based on polarity and solubility. FT-ICR MS analyses of each
if these fractions yielded spectra quite different from those of unfractionated
crude oil. However, the spectrum acquired from the aromatics fraction
was very similar to those of the unfractionated crude oil. The class,
carbon number, and double-bond equivalence distributions obtained
from each fraction were in agreement with what is expected from each
SARA fraction. The data acquired from SARA fractions can be used to
generate four peak lists for each crude oil sample. A master peak
list, representing crude oil, was created by adding the same amount
of a synthetic standard compound to each fraction. The abundance of
the other peaks relative to the standard was used to combine the four
peak lists into a single list. The number of compounds in the master
list was twice that obtained by APPI FT-ICR MS analysis of unfractionated
crude oil. Numerous NO
x
and SO
x
class compounds, which were not observed in the
direct analysis of unfractionated heavy crude oils, were abundant
in the resins fraction. Overall, this study shows that combining chromatographic
techniques, including fractionation, with high-resolution MS is needed
for a more complete understanding of the heavy molecules in petroleum.
The molecular composition of two shale oils (from U.S. Western and Russian Slanet mines) was studied using 15 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with electrospray ionization (ESI) and atmospheric pressure photoionization (APPI). Together, these techniques allowed for the identification of ∼30 000 chemical components. The class and double-bond equivalence (DBE) distributions of the shale oils were compared to those of conventional oil. N
x
classes were abundant in U.S. Western shale oil, and O
x
and NO
x
class compounds were in the Russian Slanet shale oil. The observed class distribution matched well with the high nitrogen content of U.S. Western shale oil and the high oxygen content of Russian Slanet shale oil. Aromatic hydrocarbon was significantly less abundant in the shale oils than in conventional oil. Following studies of the major components, structures were suggested in accordance with the DBE distribution of each class. The DBE distributions of the N1 and aromatic hydrocarbon classes were lower in the shale oils than in conventional oil. O2 compounds with DBE = 1 were abundant in the shale oils, whereas O2 compounds with DBE = 3−4 predominated in conventional oil. These findings combined with the previously reported results suggest that shale oil resembles less biodegraded oil.
The awareness of symptoms of global warming and its seriousness urges the development of technologies to reduce greenhouse gas emissions. Carbon dioxide (CO(2)) is a representative greenhouse gas, and numerous methods to capture and storage CO(2) have been considered. Recently, the technology to remove high-temperature CO(2) by sorption has received lots of attention. In this study, hydrotalcite, which has been known to have CO(2) sorption capability at high temperature, was impregnated with K(2)CO(3) to enhance CO(2) sorption uptake, and the mechanism of CO(2) sorption enhancement on K(2)CO(3)-promoted hydrotalcite was investigated. Thermogravimetric analysis was used to measure equilibrium CO(2) sorption uptake and to estimate CO(2) sorption kinetics. The analyses based on N(2) gas physisorption, X-ray diffractometry, Fourier transform infrared spectrometry, Raman spectrometry, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to elucidate the characteristics of sorbents and the mechanism of enhanced CO(2) sorption. The equilibrium CO(2) sorption uptake on hydrotalcite could be increased up to 10 times by impregnation with K(2)CO(3), and there was an optimal amount of K(2)CO(3) for a maximum equilibrium CO(2) sorption uptake. In the K(2)CO(3)-promoted hydrotalcite, K(2)CO(3) was incorporated without changing the structure of hydrotalcite and it was thermally stabilized, resulting in the enhanced equilibrium CO(2) sorption uptake and fast CO(2) sorption kinetics.
Laser desorption ionization (LDI) coupled to Fourier
transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was
used to analyze shale oils. Previous work showed that LDI is a sensitive
ionization technique for assessing aromatic nitrogen compounds, and
oils generated from Green River Formation oil shales are well-documented
as being rich in nitrogen. The data presented here demonstrate that
LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds
and, therefore, is a suitable method for characterizing compounds
with condensed structures. Additionally, LDI generates radical cations
and protonated ions concurrently, the distribution of which depends
upon the molecular structures and elemental compositions, and the
basicity of compounds is closely related to the generation of protonated
ions. This study demonstrates that LDI FT-ICR MS is an effective ionization
technique for use in the study of shale oils at the molecular level.
To the best of our knowledge, this is the first time that LDI FT-ICR
MS has been applied to shale oils.
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