Sythensisand Modified Of Titanium Silicon Molecular Sieve And Performance Of Desulfurization

Liquid fuel sulfur content standards are becoming more and more stringent withatmospheric pollution aggravating quickly. Due to the frequent fog and haze recently,the sulfur content in diesel has became the focus of public concern. The problems ofthe traditional hydrodesulfurization(HDS) technology in the production of low sulfuroil have become increasingly evident. Zeolites have been widely used in the field ofpetroleum refining, organic synthesis, gas adsorption due to the properties of uniquepore structure, high specific surface area and other good features. Ti-MCM-41molecular sieve is an ideal solid catalyst, the hexagonal mesoporous structure, theregular pore arrangement and Ti4+oxidation activity center make it have betterprospects of application in the catalytic oxidation reaction, especially withmacromolecular as reactants. Studies have suggested that Ti-MCM-41shown thebetter catalytic effect in catalytic oxidation reactions. In this thesis, TS-1,Ti-MCM-41molecular sieve were prepared by hydrothermal synthesis.Cu/Ti-MCM-41was synthesized molecular sieve by impregnation method withTi-MCM-41as supporter. The main content of this paper as follows:(1) TS-1, MCM-41, Ti-MCM-41molecular sieves were synthesized withtetrapropyl-ammonium bromide(TPAB), Cetyltrimethyl-ammonium bromide(CTAB)as template agent; Tetraethoxysiliane(TEOS) as silica source, Tetrabutyltitanate(TBOT) as titanium source, respectively. All the samples were characterizedby XRD, SEM, TEM, FT-IR, UV-Vis, BET, etc. It was found that the type ofcrystallization conditions had an important influence on the Zeolites’ morphology, different alkali sources will lead to the synthesis of Ti-MCM-41molecular sievewith different morphology(such as spherical, sheet, plate, etc.). Under the conditionsof120°C, a smaller amount of template and short crystallization time, the productshowed high crystallinity and narrow pore size distribution. After calcined processthe samples as-synthesized get a specific surface area of823.8m2/g, a pore volumeof0.8126cm3/g, average pore size of2.55nm.(2) The catalytic oxidation properties of TS-1, Ti-MCM-41were evaluated withthiophene(TH) and benzothiophene(BT) as model sulfide. The conditions of removalof thiophenes in model oil by zeolite were optimized. The results showed that TS-1have higher activity in the reaction of catalytic oxidation of thiophene(TH) with adesulfurization rate of89.4%, while Ti-MCM-41showed higher activity in thereaction of catalytic oxidation of benzothiophene(BT) with a desulfurization rate of92.2%. The best desulfurization conditions ware reaction temperature60oC, theamount of catalyst0.2g, H2O2/S molar ratio6and reaction time1h. The sterichindrance of zeolite was the main cause of the different catalytic effect of TS-1,Ti-MCM-41on thiophene(TH), benzothiophene(BT).(3) Ni-TS-1molecular sieve has been synthesized successfully. Characterizationresults shown that the MCM-41skeleton structure remains unchanged after theincorporation of Ni. Ni/TS-1was synthesized molecular sieve using theimpregnation method. Detection the desulfurization performance of TS-1, Ni-TS-1,Ni/TS-1molecular sieve using benzothiophene(BT) as model sulfide.(4) Cu/Ti-MCM-41,Cu/Ti-HMS molecular sieves were synthesized by theimpregnation method. Characterization results showed that Cu presented in the formof CuO on the surface of zeolite molecular sieve, Cu/Ti-MCM-41still kept along-range ordered hexagonal mesoporous structure; The surface CuO changed thediameter of the pore outlet of Ti-MCM-41and Ti-HMS mesoporous molecular sieveso that the outlet of pore diameter of Cu/Ti-MCM-41and Cu/Ti-HMS got smallerand more centralized; The π-bond complex ligand adsorption of CuO played a keyrole in desulfurization experiments, which could make it easier to adsorbbenzothienyl(BT) to the surface of the molecular sieve. The highest desulfurizationrate reached92.8%. Regeneration experiments show that the catalytic effect gotworse with the increase of frequency of use. Analysts believed that the lost of CuOspecies and collapsed of molecular sieve structure in each regeneration process led tothe results.