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Mesoporous γ-Alumina Formed Through the Surfactant-Mediated Scaffolding of Peptized Pseudoboehmite Nanoparticles

2010; American Chemical Society; Volume: 26; Issue: 12 Linguagem: Inglês

10.1021/la101266d

1520-5827

Zhaorong Zhang, Thomas J. Pinnavaia,

Covalent Organic Framework Applications

Mesoporous γ-alumina with precisely controlled mesoporosity is synthesized through the scaffolding of pseudoboehmite nanoparticles in the presence of a nonionic surfactant as the porogen. In the initial step of the synthesis, a colloidal suspension of pseudoboehmite is prepared by peptizing pseudoboehmite in dilute acidic solution. The nanoparticles in the peptizate are then assembled into a scaffold structure using nonionic Tergitol 15-S-7 (C15H33(OC2H4)7OH) as the surfactant porogen. Calcination of the resulting surfactant-containing composites at 500 °C removes the surfactant and concomitantly converts the pseudoboehmite crystallites to γ-alumina through topochemical transformation with the retention of the scaffold structure. Depending on the surfactant to alumina ratio used to form the scaffold structures, the average pore size can be precisely controlled over the range of 3.5−15 nm. Also, the BET surface areas of the scaffold structures are substantially larger in comparison to the γ-alumina formed from pseudoboehmite at the same calcination temperature in the absence of surfactant (296−321 vs 238 m2 g−1). The substantial improvement in surface area provided by the scaffold structures, together with the ability to provide narrow pore size distributions over a wide range of average pore sizes by simply adjusting the surfactant content, should substantially improve the effectiveness of this oxide as an adsorbent and as a catalyst or catalyst support.