MODIFICATION OF HIGHLY REACTIVE TRANSITIO N ALUMINAS

By combination of mechanical pretreatment of coarse-dispersed gibbsite , alpha-Al(OH)(3), with the shock calcination of these treated particl es partial crystalline transition aluminas can be obtained. The produc ts are characterized among other things by a high portion of 5-fold co ordinated Al(3+)ions ((27)AlMASNMR), remarkable differences in the RDF and a high solid state reactivity. The same properties can be produce d by direct shock calcination of highly dispersed gibbsite of uniform morphological structure. In the course of subsequent rehydration - sim ultaneously by presence of promoting components (La3+, Y3+, Ce4+, Zr4) - the conversion of the solid particles into a fibrillar boehmite, A lOOH, containing the promotor ions occurs. The calcination of this mod ified boehmite causes the formation of highly dispersed, phase- and th ermostabilized gamma-Al2O3.