Chemical Composition of Group II Lubricant Oil Studied by High-Resolution Gas Chromatography and Comprehensive Two-Dimensional Gas Chromatography

Abstract

A detailed chemical composition analysis of group II type lubricant oil has been accomplished by high-resolution gas chromatography (HRGC) and comprehensive two-dimensional gas chromatography (GCxGC). The major advantage of these techniques is the ability to obtain the detailed fingerprint of major paraffin components. To achieve the superior low-temperature property in lubricant oil via dewaxing processes, it is critical to monitor the change of key components (paraffins) in order to understand the effect of paraffins on the low-temperature property of base oil and the mechanism of each dewaxing process as well as the effectiveness of each process. Comprehensive two-dimensional gas chromatography (GCxGC) provides a better separation between the paraffins and naphthenes in the lubricant oil. Based on the quantitative analysis of GCxGC results, a formula has been developed to correlate the paraffin chemical composition to one of the low-temperature property, viscosity measured by a mini-rotary viscometer (MRV). The ability of correlating the paraffin chemical composition to MRV viscosity makes the better understanding of the role of various paraffin molecules in MRV viscosity. This knowledge is important in managing this MRV viscosity under different applications. In addition, this knowledge can be used in the lubricant base oil formulation, in the additive package development, as well as a model to predict MRV viscosity from the chemical composition.