Structural evolution of hierarchically macro/mesoporous Al2O3 monoliths under heat-treatment

Hierarchically macro/mesoporous alumina monoliths were successfully fabricated from a facile sol–gel process by introducing PEG8000 to the reaction solution of ordered mesoporous Al2O3 (OMA, P123/isopropoxide aluminum/HNO3). The monolithic gels were subsequently calcined at different temperatures to investigate the morphological evolution. Monolithic skeletons were obtained in the dried gels with bimodal close-celled macropores. The bimodal macroporous structure is preserved after calcination at 450 °C. The macropores are interconnected with large-sized mesopores, which facilitates the monolith with high surface area of 286.9 m2/g and pore volume of 0.67 cm3/g. This hierarchical feature persists up to 1100 °C after phase-transformation from γ-Al2O3 to α-Al2O3 with the shrinkage of macropores and expansion of mesopores.

Alumina monoliths were successfully fabricated from a facile one-pot process by introducing PEG8000 to the reaction solution of ordered mesoporous alumina (OMA). The monoliths are composed of close-celled macropores interconnected with large-sized mesostructured walls. The monolithic and hierarchical features can be maintained after 450 °C calcination.Figure optionsDownload as PowerPoint slideHighlights
► Alumina monolithic gels were successfully synthesized from a facile sol–gel process.
► The dried monolithic gel is in macroporous morphology with close-celled mesopores.
► The hierarchical morphology can be maintained after been sintered at 1100 °C.