Preparation Of Solvent-free Self-assembled TiO₂-supported NiMo Catalysts And Their Catalytic Performances For HDS

Sulfur oxide emissions from the combustion of fuel can not only poison the catalyst of motor vehicle tail gas,but also be the main pollutant of air pollution.As a result,the sulfur content in fuel oil is strictly limited at home and abroad,which puts forward higher requirements for hydrodesulfurization catalyst.TiO₂ material has strong electron-metal interaction with metal components,which is not only conducive to the dispersion of metal species,but also can adjust the electronic structure of metal species.At the same time,TiO₂ has a significant synergistic effect on Co（Ni）Mo（W）component in the hydrodesulfurization process,so TiO₂ material is an excellent hydrodesulfurization catalyst carrier.Compared with the traditional process,the solvo-free self-assembly synthesized TiO₂ material avoids the use of solvent,greatly improves the yield and synthesis efficiency of the target product,reduces environmental pollution,and reduces the cost and energy consumption.In this paper,we synthesized a series of TiO₂ materials by solvent-free self-assembly method.In this paper,a series of TiO₂ materials were synthesized by solvent-free self-assembly method,and Ni-Mo active components were supported by step-by-step equal volume impregnation method to prepare catalysts.Their physical and chemical properties were characterized and their hydrodesulfurization activity was evaluated.The hydrodesulfurization performance of titanium dioxide supported catalysts prepared by some typical methods was compared.The main research contents and results are as follows:（1）A series of TiO₂ supports（TiO₂-X）were prepared by solvent-free self-assembly method at different temperatures（300 ℃,400 ℃,500 ℃ 600 ℃）,and a series of NiMo/TiO₂ catalysts（NiMo/TiO₂-X）were prepared by carrying the active components of NiMo.Using DBT as raw material,the hydrodesulfurization activity of the series of NiMo/TiO₂-X catalysts was evaluated.The characterization results show that the carrier sample calcined by 300-500 ℃ is pure anatase with stable mesoporous structure,while the carrier calcined by 600 ℃ is a mixed phase of anatase and rutile.The NiMo/TiO₂-400catalyst showed excellent hydrodesulfurization activity because of its suitable crystal phase,suitable pore size,high acid content and ratio of Br（?）nsted acid,strong MoS₂ active phase dispersion and suitable active phase stacking number and length.the lowest residual sulfur content of the liquid phase sample was 11.5μg g^-1,and the highest desulfurization rate was 97.5%.At the same time,the hydrodesulfurization activity of pure anatase titanium dioxide supported catalyst is much higher than that of anatase and rutile mixed carrier catalyst.（2）Anatase titanium dioxide was successfully synthesized by sol-gel method,surfactant sulfuric acid carbonization method and solvent-free self-assembly method,and the catalyst（NiMo/SG-TiO₂,NiMo/CM-TiO₂,NiMo/SC-TiO₂,NiMo/SA-TiO₂）was prepared by loading NiMo active component.The hydrodesulfurization activity of four different anatase titanium dioxide supported catalysts was evaluated by using DBT as probe molecule.The results show that,among the four as-prepared catalysts,NiMo/SA-TiO₂ catalyst showed the highest catalytic activity for HDS of DBT.We believe that this is due to the synergistic effect of its moderate specific surface area and pore volume,suitable pore size,high sulfidation,high ratio of MoS₂ active phase,strong dispersion of MoS₂ active phase,suitable number and length of active phase stack and so on.