Scientists dissolve crude oil in water to study its composition

June 21, 2019

Researchers from MIPT, Skoltech, the Joint Institute for High Temperatures of the Russian Academy of Sciences, and Lomonosov Moscow State University have offered a new approach to oil composition analysis. They used high temperature and pressure to dissolve oil in water and analyze its composition. The new method is compliant with the green chemistry principle as it makes it possible to avoid using environmentally hazardous solvents. The paper was published in the Analytical and Bioanalytical Chemistry journal.

Crude oil is almost never utilized in its raw form. It is necessary, however, to know its precise composition to make refining as efficient as possible. Crude oil consists of over 100,000 compounds, with the exact composition of the sample varying based on the field it was extracted at. The extreme complexity of crude oil makes it impossible to separate into individual compounds. Heavier fractions, which are nonvolatile at 300 degrees Celsius, are yet to be properly studied. It is known that they consist chiefly of phenols, ketones, carbazoles, pyridines, quinolines, dibenzofurans, and carboxylic acids. In addition to that, crude oil from some fields may also contain sulphuric compounds. Many hydrocarbons have identical formulas, with the same number of carbon, hydrogen, and oxygen atoms, but differ in their arrangements, i.e., they are isomers.

The vastly different structures obviously exhibit different chemical properties. Heavier hydrocarbons consist of many atoms, which means more structural variability for each compound.

Mass spectrometry provides information on the elemental composition of substances and their molecular mass but often fails to distinguish between different isomers. Such information may be obtained through isotope exchange analysis. This method is based on the fact that, depending on which particular compounds constitute crude oil or some other sample, oxygen and hydrogen atoms will take more or less time to be replaced with their isotopes -- essentially the same elements, but with a different mass. Water is the most readily available and the cleanest source of isotopes, but oil is insoluble in water under normal conditions so potent acids and alkali have to be used instead. But acids tend to break down organic compounds, especially at high temperatures, thus altering the sample's composition.

It is known, however, that compounds insoluble in water may be dissolved in superheated, or supercritical, water at temperatures significantly over 100 C, so it was decided to apply this method to crude oil. The researchers proved it was possible to achieve a water-based crude oil solution by increasing the temperature and pressure and analyzed its composition. The sample was heated to 360 C in heavy water (in which the hydrogen is replaced with deuterium) at a pressure above 300 atm for one hour.

The researchers compared mass spectra of the original sample and the sample after the isotope exchange reaction. The data collected helped obtain more information on the structure of the compounds comprising crude oil. This method may be used to study other complex nonpolar compounds at the molecular level.

"Isotope labels may only be incorporated at specific positions in the molecule, similar to the lock-and-key model," said Professor of Skoltech and MIPT Eugene Nikolaev, who also heads the Laboratory of Mass Spectrometry at Skoltech. "We can analyze molecular structure by using high-resolution mass spectrometry to measure the exchange rate even when it is impossible to separate individual compounds and identify their structure with other methods."

"Light crude oil reserves are depleting. Hydrocracking of fuel oil, which is characterized by its highly complex and poorly studied molecular structure, is playing an ever greater role in gasoline production. Hydrocrackers are expensive, they are not produced in Russia, and they require the use of special catalysts. We have found a way to identify furans, pyridines, and naphthenic acids in crude oil without having to resort to the complex distillation process," says Yury Kostyukevich, one of the authors of the paper and a senior researcher at Skoltech and MIPT laboratories. "We hope our research will help better understand crude oil structure and composition, contribute to the development of new catalysts for more efficient oil refining, and enable improved oil quality monitoring in trunk pipeline systems."
-end-


Moscow Institute of Physics and Technology

Related Mass Spectrometry Articles from Brightsurf:

Discovery of a new mass extinction
It's not often a new mass extinction is identified; after all, such events were so devastating they really stand out in the fossil record.

How vitamin C could help over 50s retain muscle mass
New research shows that vitamin C could help over 50s retain muscle mass in later life.

Oncotarget: Tumor markers for carcinoma identified by imaging mass spectrometry
Volume 11, Issue 28 of Oncotarget features 'Lipid and protein tumor markers for head and neck squamous cell carcinoma identified by imaging mass spectrometry' by Schmidt et, al. which reported that the authors used MALDI imaging mass spectrometry and immunohistochemistry to seek tumor-specific expression of proteins and lipids in HNSCC samples.

Nontargeted mass spectrometry reveals PFAS substitutes in New Jersey soils
Using a nontargeted mass-spectral approach, researchers identified the presence of chloro-perfluoro-polyether-carboxylate compounds (ClPFPECAs) in soils across the state of New Jersey.

Large-scale analysis of protein arginine methylation by mass spectrometry
In this research, the researchers offer an overview on state-of-the-art approaches for the high-confidence identification and accurate quantification of protein arginine methylation by high-resolution mass spectrometry methods, which comprise the development of both biochemical and bioinformatics methods.

Proximity of hospitals to mass shootings in US
Nontrauma center hospitals were the nearest hospitals to most of the mass shootings (five or more people injured or killed by a gun) that happened in the US in 2019.

Chemists use mass spectrometry tools to determine age of fingerprints
Chemists at Iowa State University may have solved a puzzle of forensic science: How do you determine the age of a fingerprint?

Keeping guns away from potential mass shooters
Researchers from Michigan State University measured the extent to which mass shootings are committed by domestic violence perpetrators, as well as identyifying how they illegally obtain guns, suggesting how firearm restrictions may prevent these tragedies.

Who is left behind in Mass Drug Administration?
Ensuring equity in the prevention of neglected tropical diseases (NTDs) is critical to reach NTD elimination goals as well as to inform Universal Health Coverage (UHC).

A mechanism capable of preserving muscle mass
By studying the young and aging muscles in mice, researchers from the Myology Research Center (Sorbonne Universite-Inserm) of the Institute of Myology identified a protein, CaVbeta1E that activates the factor GDF5.

Read More: Mass Spectrometry News and Mass Spectrometry Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.