Improvement of octane number in FCC gasoline through the extraction with urea/thiourea complex based on property analysis

In the research described in this paper, the uses of the urea/thiourea complexation approach were employed to enhance the octane number of FCC gasoline by extracting n-alkanes. It was observed that adding thiourea improved the removal of the n-alkanes from gasoline, and matching results were obtained from experiments using model samples. Molecular dynamics simulation revealed that the stability of urea complexes increased as the carbon number of the n-alkanes was raised, whereas lighter n-alkane molecules exhibited a lower propensity for complex formation with urea. This finding is in agreement with the results of the DSC measurement at the decomposition temperature. Furthermore, infrared spectrum analysis, XRD characterization, and reaction heat measurements indicated that although thiourea was introduced into the reaction system, it did not actively participate in the complexation reaction. In summary, the introduction of thiourea resulted in an increased solubility of urea in an ethanol solution and enhanced the reaction heat, suggesting its beneficial role in promoting urea complex formation and facilitating n-alkane removal from FCC gasoline.

Keywords: Urea; Thiourea; FCC gasoline; Thermoanalysis; Molecular dynamics.