Study On Preparation Of Supported Skeleton Nickel Adsorbent And Its Adsorption Desulfurization Preformance

SO₂ emitted by the combustion process of sulfides in fuel oil poses a hazard to the atmosphere.In recent years,as the quality of crude oil has gradually become heavier and higher-sulfurized,the sulfur content in oil products has become higher and higher.With the increasing awareness of environmental protection,the related environmental regulations have increasingly strict restrictions on sulfur emissions.Therefore,it is particularly urgent to carry out research on oil-desulfurization technologies.The paper was mainly focused on the preparation of a new type of supported metal skeleton desulphurization adsorbent and its application on oil desulfurization process.Nickel-aluminum alloy powder(Ni/Al)and pseudo-boehmite(PB)were used as raw materials and prepared as supported nickel skeletal adsorbents(Raney Ni/Al₂O₃)through kneading,extrusion molding,dry roasting and alkali-dissolving activation.And Zn O and other transition metals was used to modify the adsorbent.Texture properties of the prepared adsorbents were characterized by XRD,BET,SEM,H₂-TPR and TG-DTA.The adsorption desulfurization performance was evaluated by using thiophene as model sulfide and cyclohexane as solvent.The mass ratio of Ni/Al alloy powder and PB had a significant effect on the adsorption capacity of adsorbent.The desulfurization capacity of the adsorbent prepared by the low content of Ni/Al alloy powder was small.On other hand,the proportion of high alloy powder was not favorable to the molding of adsorbents.Therefore the ratio of Ni/Al alloy powder and PB was reasonably selected to be 1:1.The adsorbent desulfurization performance could be greatly improved through a certain amount of Zn O additives during the preparation of the adsorbent precursor,and the adsorption capacity of adsorbent modified by 12%Zn O increased from 8.6 mg/g to 18.4 mg/g.Calcination temperature of the precursor of Raney Ni-Al₂O₃adsorbent modified by 12%Zn O was also investigated.The results showed that calcination temperature had important effect on the size of the surface active metal of Raney Ni/Al₂O₃ adsorbent.The calcination temperature was higher,the grain size of the surface active was larger.The generated Ni O during calcination process more strongly interacted with the supportor,which resulted in a lower dispersion of the surface active metal of the adsorbent,and Ni O is more difficult to be reduced.The suitable calcination temperature was about 500°C.The transition metal modification could improve the saturation adsorption capacity of the adsorbent to a certain extent,and the modification effect of Ag is better.When the adsorbent with a ratio of Zn O:Ni/Al:PB=0.27:1:1 was modified by the Ag additive,the adsorption capacity of the adsorbent could be significantly increased.When the addtion of Ag was 5%,the sulfur adsorption capacity increased by 15.7%.At the same time,the optimum adsorption conditions for the adsorbents prepared were 320°C,1 MPa,2.0 h^-1,and the ratio of hydrogen to oil was180,and the desulfurization capacity of the adsorbent reached 21.3 mg/g.Adsorbent regeneration performance was investigated.The results showed that the adsorbed material on the surface could be effectively removed by high temperature calcination in air atmosphere.The regeneration degree of adsorbent was greatly affected by the calcination temperature.Higher calcination temperature could easily lead to the aggregation of the adsorbent surface active component Ni species and Ag additives.However,lower calcination temperature conld not completely remove the adsorbed material on the surface.Therefore,it was considered that a suitable regeneration temperature was 600°C and the regeneration time was 4h,and the adsorption performance of regenerated adsorbent could be recovered as fresh adsorbent.