Study On Synthesis And Properties Of Ni₂P Catalysts For Hydrodesulfurization

Ni₂P with highly mechanical strength and hydrogenation activity could be widely applied in industrial catalytic Hydrodesulfurization?HDS?field in the future.However,due to the interaction between phosphorus source and?-Al₂O₃ in the preparation process which results in the damage of catalyst structure,it is difficult to prepare Ni₂P/?-Al₂O₃catalysts with highly active by conventional methods,such as Temperature programmed reduction?TPR?or pyrolytic reduction.For promote the application of Ni₂P in industrial hydrodesulfurization,In this paper,the?-Al₂O₃ were modified by two different method,and a highly active Ni₂P/?-Al₂O₃ catalyst was successfully obtained.Firstly,the preparation conditions of the catalyst Ni₂P/?-Al₂O₃ were optimized,and the effects of P/Ni and Ni loading on the properties of the catalyst were investigated.The quality and dispersion of Ni₂P phase on the catalyst were measured by XRD and CO-chemisorption.It was found that P/Ni=3.5 and Ni loading=20%was the best preparation condition for the catalyst.The Ni₂P/?-Al₂O₃ catalyst prepared under this condition has the highest activity and dispersion.After determines the best preparation conditions of catalysts,we used two methods to modify?-Al₂O₃,the first method is introduced Ti O₂ as the second component in the process of the preparation of?-Al₂O₃.In this part of study.a series of?-Al₂O₃-Ti O₂composite carriers were synthesized with different TiO₂ contents,then these composite supports are then prepared as corresponding NI₂P catalysts.XRD,CO-chemisorption,N₂ adsorption have been used to characterize the products.Various characterization results showed that the surface area and pore size of the composite carrier are smaller than common?-Al₂O₃,and the dispersion of Ni₂P catalyst supported on composite carriers is lower.The catalyst activity evaluation showed that the use of the composite carriers reduced the activity of the Ni₂P catalyst,proving that the?-Al₂O₃ modification method used in this section is ineffective.The second method is to directly modulate the pore structure of?-Al₂O₃.In this part of the study,a series of?-Al₂O₃ with well-developed external surface structure was prepared by hydrothermal method.Then the Ni₂P catalysts were prepared by wet impregnation method using these?-Al₂O₃ as carrier.The as-synthesized catalysts and support were systematically characterized by means of N₂ adsorption-desorption,XRD,SEM and CO-chemisorption.Characterization results showed that most of these?-Al₂O₃supports have well-developed surface structure,and these special structure has positive effect on high disperead active component formed.Evaluation test on activity of the catalyst under ambient pressure showed that apply these?-Al₂O₃ as supports will remarkably improve the activity of the catalyst for thiophene hydrodesulfurization reaction.