WO₃/ZrO₂ Solid Superacid Catalysts Preparation And Catalysis Performance Study

As one of the main routes to produce high-octane gasoline blending components in the crude oil refining industry,alkanes isomerization has drawn much attention throughout the world because it can greatly improve the gasoline quality.For alkanes isomerization,one of the key issues is to develop catalysts with enviromentally friendly,which has been widely pursued due to its importance both in academic research and in industrial utilization.At present,a new type of catalytic materials which don’t contain sulfuric acid.This catalysts by its unique advantages and broad prospect of application in the industrial fields have attracted much attention of the researchers,especially WO3/ZrO2 and MO3/ZrO2.This type of catalysts not only overcome the defect of corrosion equipment,catalyst and the products are inseparable,recycling difficult and the waste problem,but also make up for the waker stability of SO42-ZrO2 solid superacids.They Present much better stability inH2,O2,and H2O atmosphere,Therefore,they are recognized as a kind of novel catalytic materials whichare green and have potential applications.In the present study,we focus on the effects of synthesis methods and the transition metal on the structure and catalytic behavior of WO3/ZrO2 catalysts on n-heptane hydroisomerization.In the third chapter of this thesis,impregnation reflux method were used to synthesize the WO3/ZrO2 catalysts.The hydrothermal treatment can stabilize the tetragonal phase of ZrO2,more dispersive tungsten active component can be loaded on the Zr(OH)4 support treated with alcoholation,and the catalyst prepared with this support possesses larger specific surface area.The n-heptane isomerization over the WO3/ZrO2 catalyst was carried out at w(W)=15%,W03/Zr02 were calcined at 800℃,the reaction time at 250℃,.The conversion and selectivity of n-heptane can reach 28.78%and 90.16%.In the forth chapter of this thesis,A series of Ni-WO3/ZrO2 catalysts were prepared by the impregnation method.Their crystal structure and acidity were determined by XRD、BET、NH3-TPD.The catalytic performance of the samples for the n-heptane isomerization underdifferent conditions was studied.The results showed that the addition of Ni has a great effect on catalytic performance of Ni-WO3/ZrO2 for n-heptane hydroisomerization,and the n-heptane isomerization is catalyzed by metal and acid sites.Under the conditions of n(H2)/n(n-c7H16)=12,WHSV(n-c7H16)=3.52 h-1,V(cat)=0.3 ml,Zr02 were calcined at 800℃,the reaction time at 250 ℃,The conversion of n-heptane and isomerization selectivity to i-heptane can reach 39.96%and 94.79%.