Synthesis And Characterization Of Al-TUD-1 Materials And Catalytic Performance For Hydrotreating Of Diesel

With the increasing awareness of environmental protection and the strictness of environmental protection regulations,the improvement of fuel standards and the production of ultra-clean diesel have become an inevitable requirement for sustainable development of society.The new hydrotreating catalyst with high activity is at the heart of this.The properties of the new carriers largely determine their activity,including the pore structure of the support,the acid properties and the MSI.Thence,it is urgent to develop novel materials with good structural properties.This can lay a solid foundation for the development of catalyst for the ultra-deep HDS of inferior diesel oil.Pure aluminum-based Al-TUD-1 mesoporous material has interconnected sponge-like unique pores,adjustable pore structure,large specific surface area,good stability and low price.Therefore,in this paper,Al-TUD-1?AT?material was synthesized using aluminum isopropoxide as the aluminum source.The effects of water bath temperature?30 ?,40 ?,50 ? and 60 ??and thermal treatment temperature?120 ?,140 ?,160 ? and 180 ??on the pore structure of materials and the catalytic performance of catalysts were investigated.Then the Ni Mo/AT-Wx and Ni Mo/AT-Hx catalysts were characterized by using different characterization methods,such as XRD,Raman,N₂ adsorption-desorption methods and so forth,and the hydrotreating performance showed that the modulation of pore structure properties was achieved by adjusting the synthesis conditions.Under the optmimal conditions of the water bath temperature 50 ? and the thermal treatment temperature 160 ?,the as-prepared catalyst exhibited the highest HDS?98.8%?and HDN activities?98.1%?.Furthermore,the catalysts were modified with phosphoric acid and citric acid,which modulated the acidity of the catalysts and improved the interaction between the active metal and the carrier.The Ni Mo P/AT-x and Ni Mo CA/AT-x series catalysts were prepared with different contents of phosphoric acid and citric acid.The physico-chemical properties of the materials and catalysts were characterized by different characterization methods,such as XRD,N₂ adsorption-desorption,Raman,Py-FTIR,HRTEM,H₂-TPR,XPS method and so forth,and the hydrotreating performance of the catalysts were evaluated using FCC diesel or DBT as feedstocks.The results showed that the pore properties of the catalysts after phosphoric acid modification and citric acid modification had not changed.The acid amount of the catalyst after phosphorus modification increased,the acid amount of the citric acid modified catalyst decreased.Moreover,the interaction force between the carrier and the active metal was modulated,thus the content of the easily reductible Mo species increased,and more“Ni-Mo-S-II”type active phases were formed,thereby improving the hydrorefining activity of the catalysts.Consequently,the Ni Mo P/AT-2 catalyst exhibited the highest HDS and HDN activities for FCC diesel hydrotreating,which were 99.1%and 98.5%,respectively;while the Ni Mo CA/AT-2 catalyst displayed the highest HDS?99.2%?and HDN?98.5%?activities,and DBT hydrodesulfurization activity reaching 97.6%at WHSV of 10.Finally,in order to achieve the requirements of ultra clean oil production,Ni Mo/AT catalyst was used to systematically investigate the effects of hydrotreating process conditions:temperature,pressure,WHSV and H₂/Oil ratio on the hydrotreating performance of FCC diesel.The results were as follows:350 ??5 MPa?WHSV 1.0h^-1,H₂/Oil ratio 600 was the optimum process condition;After a long period operation,the Ni Mo/AT catalyst did not show significant deactivation,indicating that the catalyst had good stability.