CATALYTIC ACTIVITY OF ALUMINAS OBTAINED BY THE THERMAL-DECOMPOSITION OF MECHANICALLY GROUND ALUMINA MONOHYDRATES, ALPHA-AL203-CENTER-DOT-H2O AND BETA-AL2O3-CENTER-DOT-H2O

The catalytic activity of gamma- and alpha-Al2O3 obtained by the thermal decomposition of alumina monohydrates, alpha- and beta-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 gamma-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, alpha-Al2O3 obtained at 530 degrees C did not show any catalytic activity despite its high specific surface area of 72 m(2)g(-1).