| Sulfur-containing compounds in transportation fuels are the most notorious and undesirable contaminants because they are converted to toxic sulfur oxides (SOX), and SO2is the foremost sulfur oxides through combustion that result in air pollution and acid rain, poison the oxidation catalysts in the emission control system and sulfur compounds in the fuel combustion causes the car exhaust catalyst poisoning reformer, resulting in three major automobile exhaust of harmful nitric oxide (NOx), hydrocarbons and carbon monoxide. Thus, ultra-deep desulfurization from transportation fuels has become an increasingly important subject worldwide, due to urgently environmental problems and increasingly stringent regulations. Oxidative desulfurization (ODS) is considered to be one of the most promising desulfurization methods for its mild reaction condition, high efficiency, simple technology, low cost, low carbon and environment-friendly. Heteropoly compounds have the advantage of unique lattice structure and high catalysis properties. Heteropoly compounds is widely used in the field of oxidative desulfurization. In this thesis, several efficiency of catalytic activity recyclable heteropoly compound catalyst have been made. The prepared catalyst was characterized by FTIR, XRD, ICP-OES, TEM, VSM, DSC/TGA and elemental analysis. And we studied the catalysis of these catalysts in the ODS process. The content of this thesis contains the following five parts.I) Keggin-type polyoxometalate catalyst Mx/nHo.6PW(Zr0.6H0.6PW, Al0.8H0.6PW, Zn1.2H0.6PW, Fe0.8H0.6PW, Ti0.6H0.6PW and Sn0.6H0.6PW) and Alx/3H3-xPW (A1PW, Al0.8H0.6PW, Al0.5H1.5PW, Al0.3H2.1PW and Al0.1H2.7PW) was prepared by6metal salts and phosphotungstate. The prepared catalyst was characterized by FTIR, XRD and DSC/TGA. Catalytic activity screening was carried out on the catalyst, it was determined that the synthesized catalysts with different metal atoms substituted showed excellent desulfurization ability in the following order:Al0.8Ho.6PW> Ti0.6H0.6PW> Zr0.6H0.6PW> Sn0.6Ho.6PW> Fe0.8H0.6PW> Zn1.2H0.6PW, and with different proportions of Al atoms and H atoms showed excellent desulfurization ability in the following order:Al0.5H1.5PW> Al0.8H0.6PW> Alo.3H2.1PW> AlPW> Al0.1H2.7PW, it was determined that the best cata was Al0.5H1.5PW. The method of catalytic extraction fuel ultra-deep desulfurization was proposed using hydrogen peroxide as oxidant and MeCN as extractants. The effects of catalyst dosage, O/S molar ratio, pre-immersion time of the catalyst in H2O2solution, reaction temperature and initial sulfur content. Under the favourable operating conditions were recommended as follows:mass ratio of catalyst dosage and simulated diesel of0.25%, O/S molar ratio of10, pre-immersion time of the catalyst in H2O2solution being8min and temperature of60℃, the sulfur content of simulated diesel was nearly0ppmw at180min. In addition, Alo.5H1.5PW showed excellent desulfurization efficiency for gasoline and diesel. As stable gasoline, the catalytic-oxidation-extraction sulfur content can be reduced from350ppmw to11.2ppmw and desulfurization ratio reached to96.8%after3times MeCN extractant. As catalytic diesel, the catalytic-oxidation-extraction sulfur content can be reduced from350ppmw to8.9ppmw and desulfurization ratio reached to97.5%after3times MeCN extractant. And the catalyst recovered demonstrated almost the same activity the fresh after5cycles.Ⅱ) In this paper, a suitable organic cations assembled into new heteropoly anion having special performance0organic-inorganic heteropolyacids catalyst by displacement reaction. In this paper, organic-inorganic heteropolyacids were prepared, including [π-C5H5NC16H33]3[PO4(WO3)4],[π-C5H5NC16H33]3[PO4(WO3)4] and [π-C5H5NC16H33]3[PO4(WO3)4]. All the organic-inorganic heteropolyacids catalyst has Keggin-type structure by FT-IR analysis. Catalytic activity screening was carried out on the catalyst, it was determined that the synthesized catalysts showed excellent desulfurization ability in the following order:[π-C5H5NC16H33]3[PO4(WO3)4]>[π-C5H5NC16H33]3[SiO4(WO3)4]>[π-C5H5NC16H33]3[PO4(WO3)4]. It was determined that the best cata was [7π-C5H5NC16H33]3[PO4(WO3)4]. The method of catalytic extraction fuel ultra-deep desulfurization was proposed using hydrogen peroxide as oxidant and MeCN as extractants. The effects of catalyst dosage, O/S molar ratio, pre-immersion time of the catalyst in H2O2solution, reaction temperature and initial sulfur content. Under the favourable operating conditions were recommended as follows:mass ratio of catalyst dosage and simulated diesel of0.25%, O/S molar ratio of10, pre-immersion time of the catalyst in H2O2solution being0min and temperature of50℃, the sulfer content of simulated diesel can be reduced from500ppmw to0.5ppmw, with a desulfurization efficiency of99.9%at180min. It also shows that the oxidation reactivity of different sulfur compounds was in the order of DBT>4.6-DMDBT> BT> TH. The result shows the electron density of sulfur compounds on the sulfur atoms and the space steric hindrance were two important factors in the ODS. Moreover,[π-C5H5NC16H33]3[PO4(WO3)4] for real gasoline and diesel catalytic oxidative desulfurization obtained with good effect meet the EPA low-sulfur fuel standards. And the catalyst recovered demonstrated almost the same activity the fresh after3cycles.Ⅲ) To prepare ion exchange resin composite with heteropoly compounds catalyst several types of ion exchange resin has been used, including HPW/D296, HPW/D201, HPW/D081, HPW/D001-CC and HPW/201×7. Catalytic activity screening was carried out on the catalyst, it was determined that the synthesized catalysts showed excellent desulfurization ability in the following order:HPW/D296> HPW/D201> HPW/201×7> HPW/D081> HPW/D001-CC. It was determined that the best cata was HPW/D296. The method of catalytic extraction fuel ultra-deep desulfurization was proposed using hydrogen peroxide as oxidant and MeCN as extractants. The effects of catalyst dosage, O/S molar ratio, pre-immersion time of the catalyst in H2O2solution, reaction temperature and initial sulfur content. Under the favourable operating conditions were recommended as follows:mass ratio of catalyst dosage and simulated diesel of2.70%, O/S molar ratio of28, pre-immersion time of the catalyst in H2O2solution being8min and temperature of60℃, the sulfer content of simulated diesel can be reduced from500ppmw to32.5ppmw, with a desulfurization efficiency of93.5%at180min. And the catalyst recovered demonstrated almost the same activity the fresh after3cycles. Under the favourable operating conditions, it was determined that the synthesized catalysts showed excellent desulfurization ability for real fuel oil in the following order:stable gasoline> catalytic diesel>-10#diesel>straight-run diesel. Subsequently, the stable gasoline and catalytic diesel (acidity, density, water soluble acids and alkalis, corrosiveness to copper, mechanical admixtures, octane number and cetane number) after desulfurization, and the yield were discussed, refined found stable after octane number of gasoline and diesel fuel cetane number has slightly improved, thereby enhancing the stability of the fuel. The stable gasoline desulfurization efficiency85.1%and the recovery rate96.5%. The catalytic diesel desulfurization efficiency84.0%and the recovery rate98.0%.IV) The Keggin-type magnetic isolated heteropoly compound composite nanocatalyst (HPW/Fe3O4-SiO2) was synthesized and characterized by FT-IR, XRD, VSM, TEM and elemental analysis. The results show that the catalyst prepared with typical "pit" type core-shell structure, the catalyst particle size of about300nm. Under the favourable operating conditions were recommended as follows:mass ratio of catalyst dosage and simulated diesel of4.0%, O/S molar ratio of20, pre-immersion time of the catalyst in H2O2solution being8min and temperature of70℃, the sulfer content of simulated diesel can be reduced from500ppmw to3.0ppmw, with a desulfurization efficiency of99.4%at180min. In addition, HPW/FesO4-SiO2showed excellent desulfurization efficiency for gasoline and diesel. As stable gasoline, the catalytic-oxidation-extraction sulfur content can be reduced from350ppmw to12.8ppmw and desulfurization ratio reached to96.3%after3times MeCN extractant. As catalytic diesel, the catalytic-oxidation-extraction sulfur content can be reduced from350ppmw to10.2ppmw and desulfurization ratio reached to97.1%after3times MeCN extractant. And the catalyst recovered easily by strong magnetic field, and demonstrated almost the same activity the fresh after3cycles.V) Hollow silica were prepared by dispersion aggragation before uploading HPW. The prepared catalyst was characterized by N2adsorption/desorption FTIR, XRD and SEM The method of catalytic extraction fuel ultra-deep desulfurization was developed using hydrogen peroxide as oxidant and MeCN as extractants. The effects of catalyst dosage, O/S molar ratio, pre-immersion time of the catalyst in H2O2solution, reaction temperature and initial sulfur content were investigated. Under the favourable operating conditions recommended as follows:mass ratio of catalyst dosage and simulated diesel of1.0%, O/S molar ratio of15, pre-immersion time of the catalyst in H2O2solution being4min and temperature of60℃, the sulfur content of simulated diesel can be reduced from500ppmw to3.0ppmw, with a desulfurization efficiency of99.4%at180min. The overal desulfurization efficiency reaches99.3%, higher than that by mere extraction by45.1%, efficiency significantly. Moreover, NH4PW-SiO2for real gasoline and diesel catalytic oxidative desulfurization was obtained with good effect and the catalyst recovered demonstrates almost the same activity as the fresh after5cycles.VI) Based on the researeh of the catalytic oxidation reaetion kinetics of various typical organic sulfide single component imitation systems, it was determined that the apparent teaction series for level1, and the order of the apparent activation energy of organic sulfide is that DBT>4.6-DMDBT> BT> TH. Probing into the catalytic organic sulfide in desulfurization mechanism by FT-IR, and dynamic monitoring of over-stretching vibration of O-O changes. It was determined that Keggin-type negative ion is firstly oxidized as{PO4[WO(μ-O2)(O2)]4}3-by H2O2, and then electron-rich sulphones were extracted out from oil solution using MeCN as extracting agents. |
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