Process for the preparation of finely divided aluminas or alumina- magnesia spinels having homogeneous pore structure

摘要

Processes for the preparation of pure alumina powders or pure non- stoichiometric alumina-magnesia spinel powders starting with ammonium alum-based compositions which are dehydrated, the dehydration being carried out on dehydrated salts having a bulk density less than 0.2 kg/dm. sup.3 and wherein the dehydration is followed by a calcination with a heating schedule containing at least one intermediate stage at 750 to 850 C., the process of the invention permitting the reproducible production of such aluminas or spinels having specific surfaces of from 100 to 200 m.sup.2 /g and characterized by a very high homogeneity which guarantees a rigorously unimodal pore structure, such aluminas and spinels being useful in preparing isotopic enrichment barriers for gaseous diffusion, as well as metal polishes, catalysts, and catalyst supports.