超临界条件下合成晶型骨架的介孔氧化锆

采用聚氧乙烯型非离子表面活性剂(PEO)为模板剂,超临界乙醇为介质,在不同条件下(各种PEO,不同pH值和络合剂)合成了类似于MSU的介孔氧化锆.XRD,N₂物理脱吸附曲线,TEM及选区电子衍射证明该介孔氧化锆骨架为四方晶型;改变表面活性剂类型、络合剂及pH可调变介孔氧化锆的BET表面积与孔分布.

Synthesis of Mesoporous Zirconia with Crystalline Framework in Super-critical Ethanol

By using nonionic polyethylene oxide surface(PEO) as a template, mesoporous zirconia was synthesized in super critical ethanol under different conditions(wide pH, various types of PEO and different chelates). XRD, N 2 adsorption desorption isotherm, TEM and selected area electron diffraction confirmed that the as synthesized powder was mesoporous zirconia with tetragonal walls. Similar to MSU silica, mesoporous zirconia showed single XRD in small angle, spongy like pore arrangement and non monotonic relation between the pore size and the surfactant length. Thus, the analogous assembly mechanism most likely took place for PEO as the template by forming micelles in thermal ethanol. BET surface area and pore size could be modified by varying PEO, pH and chelate. The as synthesized mesoporous zirconia had poor thermal stability. It might be because the calcination caused further crystallization and the deformation of crystalline framework, thus losing the meaoporous structure. It is well known that some oxides such as SiO 2 , Al 2O 3 or TiO 2 can effectively stabilize totragonal zirconia. Therefore, incorporation with SiO 2 , Al 2O 3 or TiO 2 , the meso structure of zirconia successfully retained on the calcination at 673 K, or even up to 723 K in some cases. The related work will be published later. WT5HZ]