| In view of more stringent environmental legislations and expanding continue of crude oil and heavy qualitative inferior trend in the fuel oils, sulfur, nitrogen and aromatic's removal from oil have becoming an important problem to be resolved. It has become direction of raiseig the diesel production low sulfur, low aromatics especially polyaromatic hydrocarbon, high hexadecane value and low density clean diesel quality. It will have important practical significance to improve the quality of our diesel.It is very urgently to develop efficient refine catalysts to meet aromatic oil depth hydrotreating requirements.In recent years the research and development of depth efficient catalyst hydrotreating mainly focus on the components and active higher more excellent carrier.Composite oxide has become the focus in domestic and foreign scholars,it can not only the carrier of complementary advantages of different oxide and modulation carrier properties easily, but also produce a new properties single oxide doesn't have.In the thesis, The composite oxide support of SiO2-TiO2-ZrO2 was prepared by coprecipitation method and sol-gel method for the first time.Active components MoP were co-impregnated on the support to form MoP/SiO2-TiO2-ZrO2 catalyst. And then characterized by XRD, nitrogen absorption, infrared spectroscopy of absorbed pyridine and scanning electron microscope; In a fixed bed reactor,The hydrofining activities of the catalysts were tested on a model compound of thiophene, naphthalene and quinoline; The influence of raw material's ratio and baking conditions on the structure of the SiO2-TiO2-ZrO2 composite oxid were examined.The feasibility of the composite oxide as the support of diesel hydrofining catalyst was examined.The main research results are as follows:1. Ternary composite oxide of SiO2-TiO2-ZrO2 (Sx) prepared by coprecipitation methodTernary composite carrier of SiO2-TiO2-ZrO2 was prepared by coprecipitation method successfully. the recipe uniform design was applicated in investigation of Carrier's raw material ratios.The composite oxide is mesoporous material, particle diameter is about 60 nm.Compared with single and binary composite oxide,SiO2-TiO2-ZrO2 composite oxide's specific surface area, the thermal stability and crystal stability are obviously improved.When roasting temperature is 500℃and the nsi/nTi/nzr ratio is equal to 0.163/0.809/0.028, the crystal structure is most obvious and the surface structure is optimal,the specific surface can get 384.47 m2/g,pore volume is 0.72 cm3/g and the aperture is 26.2nm; It is typical mesoporous materials with large specific surface. Carrier has good crystalling phase stability and thermal stability.Si/Ti/Zr atomic ratio of composite oxide has great influence on the surface structure,the Surface properties of composite oxide can be controlled by adjusting the Si, Ti, Zr atomic ratios.2. The SiO2-TiO2-ZrO2 ternary composite oxide(S15-x) prepared by sol-gel methodThe SiO2-TiO2-ZrO2 ternary composite oxide is quadrilateral or pentagons, particle diameter is about 50 nm.Compared with single and binary composite oxide,SiO2-TiO2-ZrO2 composite oxide's specific surface area, the thermal stability and crystal stability are obviously improved.Si/Ti/Zr atomic ratio of composite oxide has great influence on the surface structure,the Surface properties of composite oxide can be controlled by adjusting the Si/Ti/Zr atomic ratios.When roasting temperature is 500℃, nsi/nTi/nzr atoms ratio is equal to 0.163/0.809/0.028,the specific surface is 315 m2/g,pore volume is 0.33 cm3/g and the aperture is 12.0nm; It is typical mesoporous materials with large specific surface.The composite oxide has good crystalling phase stability and thermal stability.3. Preparation and Characterization of MoP/SiO2-TiO2-ZrO2 Catalyst (Cx and C15-x)There exists Appropriate interactions between the active components and carrier,and the active component equably dispersed totally on the carrier.SiO2-TiO2-ZrO2'surface properties have taken place great changes after loading active components,the specific surface area and pore volume dropped greatly, but aperture increase.The specific surface area of C15-x dropped more faster than Cx.Catalyst MoP/SiO2-TiO2-ZrO2 has good surface properties relatively:C11's specific surface is 291 m2/g,pore volume is 0.65 cm3/g and the aperture is 28.4 nm; C15-11's specific surface is 175 m2/g,pore volume is 0.21 cm3/g and the aperture is 15.6nm;The crystal structure of the catalyst MoP/SiO2-TiO2-ZrO2 have no significant difference after roasted on 800℃,this indicate that the catalyst has thermal stability.The MoP/SiO2-TiO2-ZrO's specific surface area and pore volume decline with the raising temperature.But it can remain large specific surface area and catalyst structure under the 700℃,this indecate that the catalyst has good thermal stability.4.Evaluation activity of catalysts MoP/SiO2-TiO2-ZrO2The effect of Si/Ti/Zr atomic ratio on hydrofining performance is big.But because the complexity of the interaction between the trend of this kind of influence, the effect isn't absolutely,each component can not absolutely according to need within the scope of certain and modulation components, get catalysts hydrogenation with good activity.SiO2-TiO2-ZrO2 composite oxides prepared by coprecipitation and sol-gel method are all excellent carrier of novel Hyrorefining catalyst.C11 has the best hydrotreating activity:HDS is 99.8%,HDA is 78.2 %,HDN is 91.7%;To C15-11:HDS is 99.6%,HDA is 80.0%,HDN is 92.5 %; Under the experimental conditions,Catalyst C11'HDS can reach 99.8%,C5 has the best HAD,82.9%;C2 has the best HDN,93.8%.Ternary carrier SiO2-TiO2-ZrO2 has more excellent activity than binary carrier in hydrotreating.The best active component load is 20%.Long cycle stability tests have been done on C11 and C15-11 for 1200 hours, hydrodesulfurization performance are stability,it indicated that two kinds of catalysts are stability and long service life.Processing actual oil with C11 and C15-11,two kinds of catalysts show good diesel hydrotreating performance,HDS is above 96%,HAD is above 65%,and HDN is above 85%. Hexadecane value increase 12-17 units. This means that two catalysts possess good industrial application foreground.5. In situ reduction and hydrogenation process conditions of MoP/SiO2-TiO2-ZrO2 catalystTo MoP/SiO2-TiO2-ZrO2 catalyst,the favorable conditions of the in situ reduction are as follows:total pressure 1.0 MPa,H2 flow rate 100.0 ml/min, heating rate≤5℃/min, and reduction temperature 600℃.The favorable conditions of the HDA were getten through single condition experiments:reaction temperature is 340℃, airspeed is 2 h-1, reaction pressure is 4.0 Mp, oil-hydrogen ratio is 500. The favorable conditions of the HDS were getten Through an orthogonal test:reaction temperature is 380℃, airspeed is 2h-1, reaction pressure is 4.OMp and oil-hydrogen ratio is 500.The influence order of each factor to the catalytic activity:reaction temperature>reaction pressure>airspeed>oil-hydrogen ratio. |
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