Transformation of Petroleum Asphaltenes in Supercritical Alcohols Studied via FTIR and NMR Techniques

Abstract

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 1H and 13C 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 “lighter” to “heavier” alcohols used but reduces in the BSF. However, the content of aromatics in the HSF increases from “heavier” to “lighter” 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 2–3 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 Ar–OAlk. According to NMR and ATR-FTIR data obtained, the alkylation–dealkylation and alkoxylation reactions make a crucial contribution to the chemical transformations of the asphaltenes.

Chemical Heterogeneity of Deposits Formed in the Flocculant Flow From Crude Oil, According to FTIR Microscopy and Chemical Imaging

“…The original studies on the application of IR spectroscopy published more than 20 years ago have unambiguously demonstrated the correlation of chemical composition of asphaltenes with the oil origin [28][29][30][31][32][33]. Prof. S. Kazarian [34] was the first to use FTIR spectroscopy with matrix detection under the attenuated total reflection (ATR) conditions to investigate the asphaltenes aggregation.…”

Oil/Water Interfacial Destabilization of Floated Oily Sludge Based on the Catalytic Decomposition of H2O2 Induced by Interfacial-Active Complexes

“…However, the Fe, Al, and some other inorganic elements in the FOS were attributed to the addition of PFS and fine clays. The FTIR spectra in Figure S1 show that the intensity of the C–O stretching (approximately 1068 cm –1 ) increased and the −OH stretching vibration occurred at 3372 cm –1 in the FOS compared to the original crude oil. This result is consistent with what was hypothesized earlier.…”

Simple Methods for the Separation of Various Subfractions from Coal and Petroleum Asphaltenes

“…Extraction of asphaltenes and their components by supercritical fluids of solvents is represented by a wide range of these solvents. There are works describing processes with supercritical fluid extraction, where asphaltene molecules were treated with supercritical solvents such as carbon dioxide, water, toluene, pentane, benzene, propane, various alcohols, , and mixed compositions . But those are just a small part of the articles in this research area.…”