| The pore structure and surface properties of support has an inportant effect on the performance of gas oil hydroprocessing catalyst.The active alumina has appropriate properties of specific surface area,pore volume and surface acidity which was widely used in preparing gas oil hydroprocessing catalyst.In this paper, the Zr modified alumina was prepared by adding zirconium oxychloride on the base of preparation pseudo-boehmite by the NaAlO2-Al2(SO4)3 method.The properties of Al2O3 were studied by the BET,Py-IR,XRD,NH3-TPD,SEM and TEM techniques.It is shown that and the crystalline phase wasγ-Al2O3 when the content of ZrO2 was below 5.6%,while with the apparance of t- ZrO2 when above this value.The specific surface area of alumina decreased with the increase of ZrO2 content,and the pore volume changed slightly from 1.12cm3·g-1 to 1.17cm3·g-1 when the content of ZrO2 was from 0 to 6.6% and decreased when above this value.The mean pore diameter increased with the increase of the content of ZrO2 which decreased when the content of ZrO2 was above 7.4%. The style of surface acidity was mainly Lewis acid to be accompanied by a small quantity of Bronsted acid.The total acid increased slightly and the strength of acid increased.Compared with the support prepared by pure Zr modified alumina,the specific surface area,pore volume and mean pore diameter of support prepared by mixed small pore aluminium hydroxide and Zr modified aluminium hydroxide were bigger.The specific surface area of support(2#) prepared by small pore aluminium hydroxide and Zr modified aluminium hydroxide adding NH4F during extrding decreased; pore volume and mean pore diameter increased;the pore distribution became disperse. The specific surface area,pore volume and mean pore diameter of support(3#) prepared by mixed of F modified aluminium hydroxide and Zr modified aluminium hydroxide increased. The Ni-Mo-W/modified Al2O3 catalysts for gas oil hydroprocessing prepared by the above supports were evaluated on 100ml small-scale fixed bed hydrgenation unit.The results suggested that the activity of HDS was 1#>3#>reference catalyst>2# and the activity of HDN was 3#>1#> reference catalyst >2#.The activity of catalysts for gas oil hydroprocessing were directly bound up with the properties of supports.The gas oil hydroprocessing technological conditions of 1# catalyst were evaluated. The results suggested that both desulfurization and denitrification activities increased with the increace of reaction temperature and H2/oil ratio. However, both desulfurization and denitrification activities decreased with space velocity increasing. These facters had more influence on denitrification activities than on the desulfurization activities.The results showed that the catalysts had high activity.The HDS was over 95%, and HDN was over 80% on the condition of 380℃, 10Mpa, LHSV 1.5h-1, H2/oil 700.The density and carbon residue of oil after hydrogeneration decreased. |
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