In situ techniques were used to investigate the hierarchical porous structure of alumina monoliths formed by the combined processes of sol–gel transition and spinodal phase separation. The addition of low molecular weight poly(ethylene oxide) (PEO) in the sol–gel reaction of aluminum chloride induced phase separation between aluminate gel and PEO solvent. In situ time-resolved small-angle X-ray scattering (SAXS) measurements revealed that structural evolution during gelation of a sample without PEO was dominated by Ostwald ripening. With PEO addition, this coarsening mechanism, occurring during a short intermediate stage (6 min), was followed by the aggregative coalescence of phase separating domains during the late stage of spinodal decomposition. The effect of PEO in the gelation mechanism also influenced the porous structure formed by calcination of the alumina monoliths. During calcination for PEO removal and conversion from xerogel to ceramic, in situ SAXS monitoring evidenced that the formation of mesopores followed the spinodal decomposition mechanism proposed by Cahn’s theory. Alumina with well-defined meso- and macropore families, high specific pore volume (2.0 cm³ g⁻¹), and high surface area (252 m² g⁻¹) was obtained as a result of spinodal decomposition during the sol–gel transition followed by heat treatment.

原位技术用于研究由溶胶-凝胶转变和旋节线相分离的组合过程形成的氧化铝整料的分级多孔结构。在氯化铝的溶胶-凝胶反应中加入低分子量聚环氧乙烷 (PEO) 导致铝酸盐凝胶和 PEO 溶剂之间发生相分离。原位时间分辨小角 X 射线散射 (SAXS) 测量表明，不含 PEO 的样品在胶凝过程中的结构演变主要受奥斯特瓦尔德熟化的影响。添加 PEO 后，这种粗化机制发生在短暂的中间阶段（6 分钟），随后是在旋节线分解后期阶段分离域的聚集聚结。PEO 在凝胶化机制中的作用也影响了氧化铝整料煅烧形成的多孔结构。在 PEO 去除和从干凝胶转化为陶瓷的煅烧过程中，原位 SAXS 监测证明中孔的形成遵循 Cahn 理论提出的旋节线分解机制。氧化铝具有明确的中孔和大孔家族，高比孔体积 (2.0 cm³ g ^-1 ) 和高表面积 (252 m ² g ^-1 ) 作为在溶胶-凝胶转变过程中的旋节线分解随后进行热处理获得的。