- Researchers mix crude oil with water by significantly raising the pressure and temperature of the composition.
- The outcomes allow a deeper investigation of the structure and composition of crude oil.
Crude oil is currently the most valuable source of fuels and materials that are used in the energy and chemical industries. However, it takes a series of chemical processes to convert such materials into a useable form.
The efficiency of the final products relies on how much we know about the structure and molecular composition of the sample. To study crude oil, scientists use various experimental techniques such as mass spectrometry, liquid and gas chromatography, X-ray photoelectron spectroscopy, and thermal gravimetric analysis.
Despite recent advances in such techniques and comprehensive research, we still don’t know much about the structure of individual molecules in low-volatility crude oil constituents and heavy petroleum fractions.
Now, a team of Russian researchers led by the Moscow Institute of Physics and Technology has invented a new technique to analyze the composition of crude oil. It doesn’t involve any environmentally hazardous solvent and follows the green chemistry principle.
Crude oil contains more than 100,000 compounds and due to its intrinsic complexity, it is very difficult to separate individual compounds. The exact composition of the crude oil varies according to the location it was extracted at.
Although many hydrocarbons have the same formula [with the same number of oxygen, hydrogen, and carbon atoms], they are arranged in different orders. Thus, each structure (isomer) exhibits different chemical properties.
To evaluate the elemental composition of substances and their molecular mass, scientists use mass spectrometry. But this technique alone is not enough to differentiate between different structures.
Reference: Analytical and Bioanalytical Chemistry journal | DOI:10.1007/s00216-019-01802-5 | MIPT
A special technique called isotope exchange analysis can be used to obtain such information. However, to use this technique, compounds of crude oil must be dissolved with some other isotopes that have a different mass.
The most appropriate and easily available source would be water, but it doesn’t dissolve in oil under normal conditions. However, it is well-known that water can be mixed in insoluble compounds at temperatures over 100 degree Celsius.
Dissolving Crude Oil In Water
The research team tried to mix crude oil with water by significantly raising the pressure and temperature of the composition. They heated the sample to 360 degree Celsius in D2O (water that contains deuterium instead of hydrogen) at 300 atm of pressure for one hour.
They found that oil effectively dissolved in superheated water and the sample (after the isotope exchange reaction) could now be analyzed easily.
The outcomes allow a deeper investigation of the structure and composition of crude oil. This technique can also be used to examine other complex nonpolar samples on the molecular level.
Scientists can now detect pyridines, furans, and naphthenic acids in crude oil using high-resolution mass spectrometry. In the future, this technique can help in the development of new catalysts that can further enhance the oil refining process, and improve oil quality monitoring systems in trunk pipelines.