Preparation And Hydrodesulfurization Properties Of Ni₂P/SBA-15Catalysts By Citric Acid Method

The research and exploration of the high reactivity of hydrotreatingcatalysts are focused, because national environmental legislation isincreasingly stringent and the world crude oil is increasingly heavy. Nickelphosphide showed excellent hydrodesulfurization catalytic performance,which is considered to be a new generation of hydrodesulfurization catalyst.Inrecent years, due to the pressure drop at the end and other characteristics, themonolithic catalyst is more and more attention.In this paper, the catalyst was prepared by citric acidcomplex-impregnation. The catalyst were characterized by XRD, BET.Making dibenzothiophene as model, the catalytic performance was evaluatedby hydrodesulfurization reaction. The change of structure andhydrodesulfurization performance of catalyst was studied on the precursorNi₂P loadings, the CA/Ni and P/Ni molar ratio. SBA-15were taken as the supporter to prepare the CA-Ni₂P/SBA-15precursors through the citric acid complexation-immersion method. DifferentCA/Ni （CA/Ni=0,0.5,1.0,1.5,2.0）, Ni₂P content （w（Ni₂P）=25%,30%,35%,40%,45%） and P/Ni （P/Ni=0.6,0.7,0.8,1.0） are considered. All the samplesretained the mesoporous structures. Especially at320℃, CA-Ni₂P/SBA-15increased the DBT conversion rates by20%comparing with Ni₂P/SBA-15catalysts. The activities were increased following the rise of capacity, and thecatalyst with w（Ni₂P）=35%presented the highest HDS activities. The activephase were the mixture phase of Ni₂P and Ni12P5when P/Ni=0.6; whenP/Ni≥0.8, it was Ni₂P. Ni₂P had the higher activities than Ni12P5. WhenCA/Ni=1.0, w（Ni₂P）=35%and P/Ni=0.8, catalyst showed the best HDSactivities for DBT.The cordierites were coated by CA-Ni₂P/SBA-15precursor repeatedly.Then the CA-Ni₂P/SBA-15/cord monolithic catalysts were made through TPRinvolving different CA/Ni （CA/Ni=0,0.5,1.0,1.5）, content of Ni₂P（w（Ni₂P）=25%,30%,35%,40%）, and P/Ni （P/Ni=0.6,0.8,1.0,1.2）. Thecatalytic activity first increased and then decreased, because the amount ofcitrate acid, content of Ni₂P and P/Ni increased. The rise of the temperaturecould make the selectivity of CHB increaseing. Both the DDS and HDSmechanisms played an important role above380℃.