Catalytic activity of aluminas obtained by the thermal decomposition of mechanically ground alumina monohydrates, α- and β-Al2O3·H2O

Abstract

The catalytic activity of γ- and α-Al₂O₃ obtained by the thermal decomposition of alumina monohydrates, α- and β-Al₂O₃·H₂O, which were mechanically ground for 0, 8 and 24 h, was investigated by means of isomerization of but-1-ene. With increasing grinding time, the specific surface area of γ-Al₂O₃ increased markedly, but the conversion of but-1-ene decreased after the sample had been ground for 24 h. This decrease is attributed to a decrease in the number of active Lewis-acid sites, i.e. tetrahedral Al sites, compared with octahedral ones and the formation of carbonates on these sites. On the other hand, α-Al₂O₃ obtained at 530 °C did not show any catalytic activity despite its high specific surface area of 72 m²g^–1.