焙烧温度对MoO_3-ZrO_2复合氧化物的结构及加氢脱硫性能的影响

EFFECT OF CALCINATION TEMPERATURE ON STRUCTURE AND HYDRODESULFURIZATION ACTIVITY OF MoO_3-ZrO_2 COMPOSITE OXIDE

采用溶胶凝胶法制备介孔MoO3-ZrO2复合氧化物,利用XRD、N2吸附-脱附及SEM对其进行表征,考察焙烧温度对其晶相结构、比表面积、孔径以及形貌特征的影响;以FCC汽油为原料,对MoO3-ZrO2经预硫化后制得的催化剂的加氢脱硫活性进行评价。结果表明:在焙烧温度为550℃时,ZrO2表面出现蠕虫状结构;焙烧温度为650℃时,开始出现Zr(MoO4)2特征峰;焙烧温度为700℃时,ZrO2由四方相向单斜相转化;适当提高焙烧温度有助于MoO3-ZrO2复合氧化物平均孔径的增大以及得到较适合的比表面积,但过高的焙烧温度会使复合氧化物烧结断裂;经650℃焙烧得到的MoO3-ZrO2复合氧化物催化剂具有较高的脱硫活性,对FCC汽油的脱硫率可达70.3%。

Mesoporous MoO3-ZrO2 composite oxides were prepared by sol-gel method and were characterized by XRD,BET,SEM and IR to study the effect of calcination temperature on crystal phase structure,specific surface area,pore size and morphology.The FCC gasoline hydrodesulfurization activity of the sulfided composite oxides was evaluated.The results show that at the calcination temperature of 550 ℃,the worm structure appeared on the surface of ZrO2;at 650 ℃,Zr（MoO4）2characteristic peaks begin to produce and at 700 ℃,ZrO2 is transformed from tetragonal phase to the monoclinic phase.It is concluded that the appropriate increase of the calcination temperature is beneficial to increase the average pore size and get the proper specific surface area,but too high calcination temperature can make composite oxide sintering and fracture.The MoO3-ZrO2 composite oxide calcined at 650℃is with the highest HDS rate of 70.3%.