ALUMINUM TITANATE FORMATION BY THE GAS-PHASE HYDROPYROLYSIS METHOD

A novel process of aluminium titanate formation by thermal decomposition of an aqueous nitric-hydrofluoric solution containing stoichiometric amounts of aluminium and titanium is described. The solution is decomposed by spraying it into a heated reactor with subsequent oxide formation and recycling of the corresponding nitric and hydrofluoric acids by means of an absorption system. The oxides formed were mostly amorphous, in a fine dispersed, homogeneously distributed form of highly reactive state. X-ray (RDA) analysis showed crystalline forms of TiO2 (anatase), complex titanium oxides, such as Ti3O5, Al2TiO5 (tialite) and AlO(OH) (boehmite). Complete formation of tialite from this oxide mixture was studied by thermogravimetry, differential thermogravimetry and differential thermal analysis. RDA of compounds formed after the successive and stepwise heating of this powder in a muffle helped in the understanding of tialite formation. The reaction was found to be time dependent and to be completed at 1400° C. Decomposition of the tialite formed into Al2O3 (corundum) and TiO2 (rutile) was observed in the temperature range 900 to 1070° C. © 1990 Chapman and Hall Ltd.