Modified SO ₄ Applied Research

The combustion products (SOx) of sulfides in fuel oil caused great harm to our environment. In reaction to this phenomenon, lots of strict regulations of fuel specifications have been implemented in many countries and regions. It is urgent to find out some novel and effective desulfurization methods of fuel oil to meet these strict regulations. SO42-/MxOy solid superacids show fine catalytic activities in almost all the acid catalyzed reactions and it also has the technical feasibility when they are used for fuel oil desulfurization which can be defined as a typical acid catalyzed reaction.A series of SO42- promoted metal oxide solid superacids:SO42-/ZrO2-WO3 SO42-/ZrO2-MoO3 and SO42-/ZrO2-Cr2O3 were prepared by incorporating different metals into SO42-/ZrO2. The above four catalysts were characterized by Fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), NH3-temperature programmed desorption techniques (TPD) and Scanning electron microscope (SEM). The results showed that the characteristic peaks of the four catalysts all presented on the range of 1040-1080 cm-1, 1130-1150 cm-1,1200-1280 cm-1, and the characteristic peaks of SO42-/ZrO2-Cr2O3 was sharpest which mean its Lewis acidity was also strongest; the proportion of tetragonal ZrO2 in 2 solid superacid was highest; the order of acid strength of these four catalysts was listed as follows:SO42-/ZrO2-Cr2O3>SO42-/ZrO2-MoO3>SO42-/ZrO2-WO3>SO42-/ZrO2; the four catalysts all had good surface dispersion and no obvious agglomeration.Then, the four prepared SO42-/MxOy solid superacids were used as catalysts for model oil oxidative desulfurization to compare their catalytic activities. SO42-/ZrO2-Cr2O3 solid superacid which had the best effect of desulfurization was selected and used in the research of oxidative desulfurization to remove dibenzothiophene (DBT), and the thchnology conditions were also optimized. The results suggested that, the optimized conditions were as follows, the reaction temperature was 70℃, the reaction time was 100 min, the oxidant dosage was V(H2O2):V(oil)=1:20 and the catalyst dosage was 0.015g/mL oil. And the removal rate of DBT reached 91.77%.Finally, SO42-/ZrO2-Cr2O3 solid superacid were used as catalyst in the research of oxidation-extractive coupling desulfurization for model oil, the thchnology conditions were optimized and the recycle of catalyst and extractant were also investigated. And the optimized conditions of oxidation-extractive coupling desulfurization were as follows, the reaction temperature was 70℃, the reaction time was 80min, the oxidant dosage was V(H2O2): V(oil)=3:80, the catalyst dosage was 0.015g/mL oil and the extractant dosage was V(DMF):V(oil)=1:1. And the removal rate of DBT can reach up to 98.56%. Compared with traditional oxiadation and extraction two-step desulfurization, oxidation-extraction coupling desulfurization can get a higher removal rate of DBT in a shorter amount of time with using less oxidant. Both the catalyst and extractant showed good recycling properties, they can be recycled 5 times and 3 times without decrease of the removal rate of DBT.