Preparation And Characterization Of La Doping On WO₃/ZrO₂ Solid Superacid Catalyst

Solid superacid has aroused great interest because of its distinct advantages such as, ease of separation from reaction mixture, no corrosion for the reactor, environmental friendly and excellent catalytic activity. In this paper, the ZrO2 support and the WO3/ZrO2 catalyst were prepared by template method, co-precipitation and impregnation methods, respectively and characterized by XRD, N2 adsorption-desorption, DTA, Hammett indicator and IR. The catalyst structure, thermal stability, acid strength, acid type, acid volume, etc were compared under the different preparation conditions(such as, preparation method, calcination temperature, W content, La content, post-processing method, etc).The research results can be concluded as below.ZrO2 support were prepared by template method and precipitation method.Compared the structure of ZrO2 prepared by the two methods. The results indicated that ZrO2 prepared by SDS template method was easy to be sintered. The crystalline phase, thermal stability, surface area, pore volume, pore size of ZrO2 that prepared by precipitation method were better than that by the SDS template method.WO3/ZrO2 solid superacid catalysts were prepared via co-precipitation and impregnation. The results showed that preparation conditions on the WO3/ZrO2 solid super-acid had great influence on the acidity. The acid structure and acid strength of WO3/ZrO2 solid superacid synthesized by co-precipitation was better than by impregnation, and better preparation conditions as follows:Zr(OH)4 PH was 9, WO3 was 10%, calcination temperature was 650℃.The tetragonal phase La2O3/WO3/ZrO2 solid acid catalyst with Ho<-12.7,high surface area (175.2843m2/g), appropriate pore size (5.99 nm) and high stability was successfully synthesized by the co-precipitation. Better preparation conditions: Zr(OH)4 PH was 9, WO3 content was 10%, La2O3 content was 1%, calcination temperature was 650℃. Lanthanum had been homogeneously incorporated into the framework of mesoporous WO3/ZrO2 solid acid catalyst. Lanthanum doping on tungstated zirconia appropriately could not only enhance the acid strength, but also stabilize the structure, increase the surface area. With the rise of the La/Zr ratio, the acid strength tended to be increased at first and then decreased.