Preparation And Evaluation Of Hydrogenation Catalysts Supported On Filler-type Porous Anodic Alumina

Catalysts supported on foller-type porous anodic alumina can be obtained by preparing a porous alumina supports via the anodic oxidation-hydration-heating treatment of thin alumina plate, and then impregnating active metals on the supports. Compared with the conventional catalysts, the catalyst can offer many advantages, such as well heat transfer ability, plasticity, anti- shock and high mechanical strength. This kind of catalyst has two functions severing as catalyst and regular filler in a catalytic distillation tower. Compared with the loading of a conventional solid catalyst, a loading of the regular filler catalyst in a catalytic distillation tower can easily avoid a loading problem, and also the loading with regular filler catalyst can provide high bed voidage, well vapor and liquid distribution, high catalytic efficiency, etc. Therefore, regular filler catalysts are more suitable for catalytic distillation processes.Porous alumina films (Al2O3-Al, regular filler support) were prepared via two-step anodization method, and Co-Mo/Al2O3-Al catalysts were obtained by impregnation with ammonium molybdate and cobalt nitrate. Selectivity and activity of the catalysts for FCC gasoline hydrodesulfurization were evaluated in a fixed bed reactor.The influences of electrolysis and after-treatment conditions on the physical properties of porous anodic alumina were investigated. Experimental results showed that high-porosity and higher surface area alumina films were obtained under the conditions of oxalic acid concentration 4 wt%, anodic time 1 h, hydration temperature 80℃and hydration time 3 h. Under the conditions above, the surface area and average pore size of porous alumina were 10.64 m2·g-1 and 5nm respectively.Using <80℃light fraction and >80℃heavy fraction of FCC gasoline as feed respectively, the Co-Mo/Al2O3-Al catalysts were evaluated in a fixed-bed reactor. Results showed that the catalyst with Co/Mo (atomic ratio) =1/2 was the best one of the catalysts examined. Under the conditions of reaction pressure 1.5 MPa, reaction temperature 350℃, H2/Oil(V/V)= 400 and WHSV 0.61 h-1, the desulfurization percentage of light fraction of FCC gasoline reached to 96.1 %, and And under the same conditions except for WHSV 0.24 h-1, the desulfurization percentage of heavy distillation of FCC gasoline could reach to 96.5 %. The catalysts exhibited desired selectivity and activity for FCC gasoline hydrodesulfurization and this implies that the Co-Mo/Al2O3-Al catalysts could be apply to the catalytic distillation processes for replacing of conventional hydrodesulfurization catalysts.