Abstract:Six Salen(M) complexes, I~VI, were synthesized from salicylaldehyde Schiff base ligands and Co(NO3)2 and Cu(NO3)2. The simulated oil system was prepared by using 1-hexanethiol, dibutyl sulfide and 2-methylthiophene as model compounds to investigate the catalytic oxidative desulfurization performance of complexes I~VI. The effects of central metal ions and ligands on the oxidative desulfurization performance of complexes I~VI were analyzed. The results showed that the order of the total desulfurization effect for the six desulfurizers on the simulated oil in 75 min was VI>V>IV>I>III>II, and the total desulfurization rate of complex VI was 31.9%. Among them, complex V exhibited the best removal effect for 1-hexanethiol and dibutyl sulfide with 74.2% and 65.1% removal rate, respectively. While complex VI had the best removal effect for 2-methylthiophene with a removal rate of 24.4%. According to the structure-property relationship analysis, the stronger the coordination ability between the central metal ion and O2, the larger the conjugated system of the ligand, and the higher density of electron cloud, the better the desulfurization performance of the complex. The products before and after oxidation of the single sulfide simulated oil system were analyzed by infrared spectroscopy (IR) and ion chromatography (IC). It was found that three sulfides were oxidized to form corresponding sulfones or sulfoxides, and 1-hexanethiol and dibutyl sulfide were further oxidized to form SO32- or SO42-.