Research On The Hydrocracking Of LCO Into BTX

In the process of hydrocracking of LCO?Light Cyclo Oil?into light aromatic hydrocarbons?benzene-toluene-xylene,BTX?,the selective hydrogenation activity of catalyst has a significant impact on the distribution of reaction products.Different kinds of hydrocracking catalysts possess different hydrogenation properties,acid properties,pore structures,and matching relationship between acid property and hydrogenation property,and then different selective hydrogenation activity.Kinetics research is of great help for evaluating the selective hydrogenation activity of catalysts.The reaction network and reaction kinetics for the hydrocracking of LCO into BTX were established in this research.By taking advantage of the lump reaction kinetics established,the effects of various properties of the catalyst on the hydrocracking reaction of LCO were studied.Firstly,the reaction network and kinetic model for the hydrocracking of LCO into BTX were established,and the influence of various hydrogenation active component on the product distribution was investigated.The hydrocracking catalysts were prepared using Beta zeolite as the carrier loaded with different metals?Ni W,Co W,Ni Mo,Co Mo?,which were characterized and their performance of LCO hydrocracking reaction was evaluated.The kinetics calculation results indicated that Co W/Beta catalyst showed good selective hydrogenation activity,and the experimental result showed that Co W/Beta catalyst achieved high yield of BTX when the space time was0.24 h^-1.And tungsten,as the main hydrogenation active cimponent,is the keystone of this research.Secondly,the balance between the acid center and metal center of catalyst was investigated.Catalysts for hydrocracking of LCO into BTX were prepared with Beta zeolite as carrier loaded different amounts of WO₃?10 wt%,15 wt%,20 wt%,25 wt%?,which were characterized and their performance in LCO hydrocracking reaction was evaluated to explore the optimum balance between the acid active center and metal active center of the catalyst.The results showed that with the increasing amount of loaded WO₃,the acid amount of the catalyst decreased,and the value of equilibrium factor BI?Balance index?,between the acid center and the metal center,increased.The BI value of 15W/Beta catalyst is suitable,of which the acid center and metal center reach a good balance.The kinetics calculation results indicated that 15W/Beta showed the best selective hydrogenation activity.And the experimental result showed that the highest BTX yield was obtained over 15W/Beta catalyst when the space time was 0.31h^-1.Finally,the influence of different mesoporous zeolite on the product distribution was investigated.A series of mesoporous Beta zeolites were synthesized by hydrothermal method emplying different amounts of STL?0 wt%,3.3 wt%,10 wt%,15wt%?as the templatre,and the catalysts for hydrocracking of LCO into BTX were prepared by using mesoporous Beta molecular sieves as the carrier.All the catalysts were characterized and their performance in LCO hydrocracking reaction was evaluated The results showed that with the increasing amount of STL template,the external specific surface area and the mesoporous volume of the catalyst decreased,which was of advantage to the transfer of target product and reducing the deep hydrogenation reaction of BTX.But the amout of acid sites content decreased significantly,and the cracking activity became weaker.Therefore,the selective hydrogenation activity became stronger due to the increase of mesoporous volume,and then became weaker because of the decrease of acidity amount.When the amount of STL template was 10wt%,the kinetics calculation results indicated that the catalyst exhibited the best selective hydrogenation activity.And the experimental result showed that the highest BTX of 34.02 wt%appeared ovewhen the space time was 0.31 h^-1.