Research On The SO₄^2-/M_xO_y Solid Superacid Catalyst

Recently,the solid superacid catalysts,SO₄^2-/M_xO_y,have attracted much more attention to the researchers'due to their strong acidity,thermal stability,environmentally amity and excellent catalytic activity. The catalysts are very attractive for petrochemical industryIt studied SO₄^2-/ZrO₂ which has the strongest acidity among the SO₄^2-/M_xO_y solid superacid catalysts,mainly about the preparation and application of solid superacid catalyst SO₄^2-/ZrO₂ for n-pentane isomerization. The solid superacid catalyst Pd-SO₄^2-/ZrO₂-WO₃ was prepared by adding noble metal Pd and using WO₃ as an secondary oxide. The catalyst was evaluated with n-pentane as feed on high pressure microreactor of 10mL continuous flow fixed-bed which was connected with online chromatogram unit. In order to study the effects of preparation methods,such as quantity of WO₃,calcination temperature,kind of impregnated solutions,concentration of H2SO4,way of adding H2SO4,concentration of H2SO4,quantity of Pd,activating temperature and activating time,on the performance of catalyst were investigated respectively,and the best preparing conditions were defined. Also,the reaction tempreture,reaction pressure,airspeed and the molar ratio of H2 and nC5 were studied to define the best technological conditions. Because of adding Pd,the catalyst possessed both abilities of the isomerization and hydrodesulfurization. The catlyst still showed steady isomerization activity even in the presence of sulfur-containing pentane.The results showed that the sample,whose mass ratio of WO₃ and ZrO₂ being 0.10,quantity of Pd being 0.05%,impregnating in the H2SO4 solution of 0.8mol/L,calcinating at 600℃and activated at 300℃for 3h in H2,is best for the reaction of alkyl isomerization. The n-pentane conversion is 65.29%,isopentane selectivity is 93.52%,isopentane yield is 61.06% and liquid product yield is 95.77% ,when the catalyst was reacted at the conditions of reaction temperature of 260℃,space velocity of 1.0h-1,H2/ n-pentane molar ration of 4.0 and reaction pressure of 2.0MPa.