Improvement of Octane Number in FCC Gasoline Through the Extraction with Urea/Thiourea Complex based on Property Analysis

In this paper, the uses urea/thiourea complexation approach was employed to enhance octane number of FCC gasoline by extracting n-alkanes. It was observed that adding thiourea improved the removal of n-alkanes from the gasoline, and matching results were obtained through the experiments using model samples. Molecular dynamics simulation revealed that the stability of urea complexes increased with raising carbon number of n-alkanes, while lighter n-alkane molecules exhibited lower propensity for complex formation with urea. This finding is in line with the results of DSC measurement at 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 ethanol solution and enhanced reaction heat, suggesting its beneficial role in promoting urea complex formation and facilitating n-alkane removal from FCC gasoline.