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Title: Use of NMR spectroscopy to study the effects of hydroprocessing on structure and thermo-oxidative stability of base oils

Author
item SHARMA, BRAJENDRA - PENN STATE UNIVERSITY
item ADHVARYU, ATANU - PENN STATE UNIVERSITY
item PEREZ, JOSEPH - PENN STATE UNIVERSITY
item Erhan, Sevim

Submitted to: Fuel Processing Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2008
Publication Date: 9/30/2008
Citation: Sharma, B.K., Adhvaryu, A., Perez, J.M., Erhan, S.Z. 2008. Use of NMR spectroscopy to study the effects of hydroprocessing on structure and thermo-oxidative stability of base oils. Fuel Processing Technology. 89(1):984-991.

Interpretive Summary: The conversion processes provide an opportunity to modify the chemistry of structures present in petroleum base oils. This improves the lubricant properties of petroleum base oils. The average structural parameters were used to study the effect of hydrogenation on structure and properties of paraffinic neutral base oils. The effect of severity of hydrogenation has also been investigated on structure and properties of three aromatic extract fractions obtained from different degree of hydrogenation of petroleum base stock. A linear relationship was found between average structural parameters and lubricant properties. Variation in oxidative stability of various samples was explained using structural parameters. The results suggest that deepest knowledge of chemical structure could help in selecting base oils to meet future product specifications. The knowledge thus gained can be utilized to improve the lubricant properties of vegetable oil base stocks, which will improve the agro-economy of the locally grown renewable resource.

Technical Abstract: The hydroprocessing technologies such as hydrocracking, hydrofinishing provide an opportunity to modify the chemistry of hydrocarbons to improve the properties of petroleum base oils. Quantitative 1H and 13C NMR data has been used to generate average structural profile for a variety of base oil samples and aromatic fractions. The average structural parameters were used to study the effect of hydroprocessing on structure and properties of paraffinic neutral base oils. In addition, the effect of severity of hydrogenation on structure and properties has been investigated on three aromatic extract fractions obtained from different degrees of hydrogenation of catalytic cycle stock. A linear relationship was found between average structural parameters and properties such as viscosity index, volatility and refractive index. Thermo-oxidative stability of samples was measured using differential scanning calorimetry and thin film micro oxidation tests. Variation in oxidative stability of various samples was explained using structural parameters. The NMR data was found useful in explaining property changes as a result of hydroprocessing. The results suggest that deepest knowledge of chemical structure could help in selecting base oils to meet future product specifications.