Study Of Nano-Hydrodesulfurization-Catalyst Ni/γ-Al₂O₃

In recent several decade years,according to the environmental legislation,the content of the sulfur in gasoline and fuel is more and more strict,but at the time,the quality of gasoline and diesel fuel is more and more low,for this reason,the production of the cleaner fuel is attention-getting by all over the world.None-lead,low-sulfur, low-aromatic hydrocarbon,high-octane number of the fuel is in the request,it is also the way producing cleaner fuel should to go.The improvement on the process of HDS(hydrodesulphurization)and developing more active hydrodesulphurization catalyst become imperative,the improvement on the process of HDS would need too much equipments and funds obviously,comparison with improvement on the process of HDS,developing more active hydrodesulphurization catalyst material is more attention-getting.In the domain of the chemical catalyst,nano-particle has high surface activity with its small grain,big surface area,and a mass of empty atoms on the surface.All of these are propitious to improve the selectivity and activity of catalysts.So nano-particle as one kind of new catalyst materials arrested so many attentions from research workers.γ-Al₂O₃ is widely used in petrochemical industry as catalyst carrier for its high melting point,high surface area,good mechanical properties and low cost. The preparation and the chemical and physical properties ofγ-Al₂O₃ have been studied for many years.Up till now the study of the preparation of nano-fibers ofγ-Al₂O₃ and its application has not been found in domestic publications and the report is rare in foreign journals.Based on conventional technology to prepare aluminum hydroxide, we synthesize pseudoboehmite in high gravity reactor by NaAlO₂-CO₂ reaction.Then,the pseudoboehmite is calcined at certain temperature for some time to get dispersed nano-fibers ofγ-Al₂O₃ powder.The structure and morphogy of the product are analyzed by XRD,TEM and BET.Theγ-Al₂O₃ powder prepared in this way is used as the catalyst carrier,it was used in thiophene-cyclohexane model chemical compound to checkout its activity.The results show that nano-catalyst was prepared by impregnation method with nano-fiberγ-Al₂O₃ as catalyst carrier,its average grain is 10-20nm,specific surface area is above 130m²/g,active ingredient is mostly the oxide of Ni.When the concentration was 8%,active ingredient dispersed uniformly and overcast the carrier completely;the particle is almost at the same size.When impregnating time was 16h,the catalyst was loaded well,as the time prolonged,the specific surface area decreased and the trend becomes weak;When calcinated under 500℃, the structure and morphogy of catalysts is best,active ingredient dispersed uniformly on the surface,its average grain is 10-20nm without agglomeration;As the increase content of Ni,the activity of desulphurization is from high to low with peak at 16%;the conversion of thiophene is in close connection with reaction temperature,as temperature rise,the conversion increased until 340℃at which the conversion did not change any more;The conversion of thiophene is in no connection with reaction pressure when it reached a certain pressure; moreover,calcinated under different temperatures,the conversion is different.