Process for making extrudates from aluminum oxyhydrates

A process consisting essentially of peptizing with an aqueous acid selected from the group consisting of nitric acid, acetic acid, citric acid, hydrochloric acid, sulfuric acid, formic acid, propionic acid, monochloracetic acid, dichloroacetic acid and trichloroacetic acid at a concentration of 0.3 to 10% a Boehmite aluminum oxyhydrate containing 65 to 85% by weight Al.sub.2 O.sub.3, a bulk density of 500 to 700 g/l, a B.E.T. specific surface area of 140 to 300 m.sup.2 /g and an average particle size below 100 microns, then adding an aqueous solution of ammonia or an ammonia liberating compound having a concentration of 0.1 to 3%, there being employed 50 to 70 parts of acid solution and 35 to 50 parts of ammonia solution per 100 parts of aluminum oxyhydrate, to form an extrudable mass, extruding said extrudable mass, drying and then calcining the extrudate.