The treatment of aluminium surfaces preventing the formation of a passivation layer allows to obtain monolithic hydrated alumina. The material is amorphous and transforms by heating into γ at 870℃ and α alumina above 1200℃. The as-prepared monoliths are ultra-porous with a density amounting to 0.2 to 1 of the alumina density. They consist of tangled filaments with large voids which induces a high specific surface. The porosity decreases after thermal treatments, but is still relatively high. After heating treatments, shrinkage occurs, but the initial shape of the monolith is conserved.
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