Preparation And Catalytic Performance Of Hydrodesulfurization On Supported Catalysts Via Hierarchically Porous Molecular Sieve As Carrier

To solve the increasingly serious environmental problems caused by the burning of fossil fuels, our country brought out laws and regulations pretending the release of sulfur content in diesel fuels. Thus the research and development of deep hydrodesulfurization catalysts to decrease sulfur in diesel combustion products are necessary. In recent years mesoporous molecular sieve such as MCM-41? KIT-1 had caused the wide attention of the scientific community. KIT - 1 has a unique three-dimensional vermicular short channel, could be widely used compared with the one-dimensional channel of MCM - 41 Micro-mesoporous molecular sieve ZSM-5/KIT-1(ZK-1) and nano AIKIT-1 molecular sieve were synthesized by hydrothermal synthesis method. The structures of the catalysts were characterized by X-ray diffraction (XRD), NH3 chemical adsorption (NH3-TPD), N2 physical adsorption, scanning electron microscope (SEM) and pyridine adsorption ir (Py - IR) by means of the carrier and catalyst pore structure and acidity, and had been used to characterize the surface active species. And catalytic performance of catalysts was investigated in hydrodesulfurization reaction of DBT and 4,6 - DMDBT.Firstly, the synthesis methods of the supported catalysts were optimized and the reaction conditions (temperature, pressure and H2/oil ratios) were investigatied. Based on the results, the desulfurization reaction rate increases with the increasing temperature and pressure after the leveled off from 340 ?,4MPa. And increases with the increasing hydrogen oil ratio, after the VH2/VoiI get 500 the desulfurization turns down significantly. Desulfurization reaction paths are also changed with different reaction conditions, high pressure and low temperature is beneficial to reaction along a path hydrodesulfurization (HYD).The catalytic performance of catalysts loaded with different Ni/Ni+Mo were investigated. The catalyst desulfurization rate increased with increasing Ni/Ni+Mo, when Ni/Mo = 0.3 the catalyst reached the highest catalyst activity, and at the condition of 320 ?,3MPa, VH2/VoiI=300 the desulfurization rate can reach 97.4%. As the Ni/Ni+Mo further increases, activity quickly reduced instead. This is due to excess metal components could form crystal phase species, blocked the carrier channels, reduces the pore size, pore volume and specific surface area.The influence of the different Si/Al of AlKIT-1 supports on the catalytic performance were investigated. The research results show that with the Si/Al increases, the pore diameter and surface area increased after the first time reached the maximum when the Si/Al = 30. Pyridine adsorption ir spectra shows that different Si/Al all have considerable weak acid and strong acid center, but strong acid center is weak. And to the catalyst L acid center is significantly stronger than the B acid catalyst. The HDS catalyst activity also first increases then decreases, the carrier of Si/Al = 30 catalyst showed close to 99% of the catalytic activity at the condition of 340 ?,4MPa, VH2/Voil=500.