Preparation Of Ordered Mesoporous Alumina And Its Hydrodesulfurization Performance

The contradiction between the demand for clean and high-quality oil products and the deterioration and deterioration of petroleum resources is becoming increasingly acute,which makes the hydrogenation burden in the clean production process of diesel oil more and more heavy,the sulfide content continues to increase,and the sulfide structure becomes more complicated.Alumina is the most widely used support material in hydrotreating catalysts,but there are some defects in the pore structure and surface properties of alumina.First,the pore distribution of ordinary alumina is not concentrated and the specific surface area is low.Such characteristics make the active metal supported on the carrier surface poorly dispersed;on the other hand,the existence of micropores has a significant inhibitory effect on the internal and external diffusion,adsorption,desorption,and conversion of complex sulfur-containing compounds;Second,the surface of alumina excessive interaction with the active metal is not conducive to the formation of a highly active active phase during the curing process of the active metal.Therefore,the physical and chemical properties of ordinary alumina can no longer be used as a support matrix material for ultra-deep hydrodesulfurization of inferior diesel oil.In view of the existing problems of ordinary alumina-based catalysts in ultra-deep hydrodesulfurization of diesel,it is necessary to find a new type of oxidation Aluminum carrier material.In this paper,ordered mesoporous alumina was prepared by the template method.By studying the crystal form,crystallinity,specific surface area,and pore structure of ordered mesoporous alumina under different preparation conditions,ordered mesoporous alumina with concentrated pore distribution,large specific surface area and large pore volume was obtained.With the optimized ordered mesoporous alumina as the support material,an ordered mesoporous alumina-based hydrodesulfurization catalyst was prepared and modified accordingly,in order to reduce the excessively strong interaction between the active metal and the carrier,generate more highly active type II active phases,improve the ability to remove complex sulfides and crack the polycyclic aromatic hydrocarbons.The metal dispersibility,surface acidity,metal reducibility,dispersibility of the active crystals of the catalyst before and after modification were studied,and the reaction laws of different catalysts on DBT and inferior diesel were studied in order to obtain different modification methods effect on hydrodesulfurization catalyst activity.The study found that different preparation conditions have an effect on the crystal form,crystallinity,specific surface area,and pore structure of ordered mesoporous alumina.Compared with ordinary alumina materials,The surface area,pore distribution concentration,and pore volume of the ordered mesoporous alumina produced are all higher than ordinary alumina.The modification of CA and P and the addition of Y molecular sieves to the catalyst both improved the reduction performance of the active metal of the catalyst.Through the study of the active photocrystals after vulcanization:the modification of CA and P increased the dispersion of Mo atoms.It shows that the modification of CA and P and the addition of Y molecular sieve in the carrier can reduce the interaction between the active metal and the carrier to a certain extent,and improve the vulcanization performance of the active metal.After the modification of CA and P,more Mo atoms are located on the outer surface of the active photocrystal,which is conducive to the adsorption and subsequent reaction of complex sulfides.CA modification has little effect on the acidity of the catalyst,while P modification and the addition of Y molecular sieves to the catalyst significantly increase the acid amount of the catalyst,improve the hydrogenolytic activity of the catalyst,and help break the C-S bond.The research on the reaction law of different catalysts on DBT and inferior diesel found that: CA and P modification can effectively improve the reaction rate constant of each reaction path of DBT;the catalysts with different modification methods can improve the hydrodesulfurization rate of inferior diesel.