9 research outputs found
Correlation between Asphaltene Stability in n-Heptane and Crude Oil Composition Revealed with Chemical Imaging
Five crude oil samples with different physical properties have been studied with respect to asphaltene stability. The attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic imaging approach of n-heptane-induced precipitation has been used to monitor crude oil behaviour under dilution with a flocculation agent. For each sample, the dynamics of asphaltene precipitation has been observed by applying this chemical imaging method. Based on these data, the stability of crude oil samples has been compared and the correlation between asphaltene stability and crude oil properties has been proposed
Transformation of Petroleum Asphaltenes in Supercritical Alcohols Studied via FTIR and NMR Techniques
The
aliphatic alcohols (methanol, ethanol, and 1- and 2-propanols)
were used for the first time as a reaction media for the upgrading
of crude oil asphaltenes. The process was realized in a batch reactor
under supercritical conditions (at 350 °C). The three main fractions
of the products (hexane- and benzene-soluble fractions, HSF and BSF,
and insoluble residue, IR) were analyzed using attenuated total reflection
Fourier tranform infrared (ATR-FTIR) and <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance (NMR) spectroscopy to characterize structural
changes of the initial asphaltenes (IA). According to NMR data, the
aliphatics are the main part of the hexane-soluble fraction (HSF)
and benzene-soluble fraction (BSF). The alcohols were appeared to
influence the content of both aliphatics and aromatics in the products.
The content of aliphatics in the HSF increases in the line from âlighterâ
to âheavierâ alcohols used but reduces in the BSF. However,
the content of aromatics in the HSF increases from âheavierâ
to âlighterâ alcohols, while this order is reversed
for the BSF. According to the ATR-FTIR spectroscopy data, the aromatics-to-aliphatics
ratios observed for the insoluble residues are 2â3 times higher
as compared with the initial asphaltenes but 2 times lower for the
HSF. The BSF are composed of less-condensed aromatics than those of
the IA. It is shown that the alcohols used as a reaction media are
incorporated in the product molecules as alkoxy substituents in aromatic
ethers ArâOAlk. According to NMR and ATR-FTIR data obtained,
the alkylationâdealkylation and alkoxylation reactions make
a crucial contribution to the chemical transformations of the asphaltenes
Synthesis of Catalytic Precursors Based on Mixed Ni-Al Oxides by Supercritical Antisolvent Co-Precipitation
Mixed Ni-Al oxide catalytic precursors with different elemental ratios (20, 50, and 80 wt.% Ni0) were synthesized using green supercritical antisolvent co-precipitation (SAS). The obtained oxide precursors and metal catalysts were characterized in detail by X-ray diffraction (XRD) analysis, atomic pair distribution function (PDF) analysis, CO adsorption, and high-resolution transmission electron microscopy (HRTEM). It was found that the composition and structure of the Ni-Al precursors are related to the Ni content. The mixed Ni1âxAlxO oxide with NiO-based crystal structure was formed in the Ni-enriched sample, whereas the highly dispersed NiAl2O4 spinel was observed in the Al-enriched sample. The obtained metal catalysts were tested in the process of anisole H2-free hydrogenation. 2-PrOH was used as a hydrogen donor. The catalyst with 50 wt.% Ni0 demonstrated the highest activity in the hydrogenation process