Abstract: This invention relates to a method for preparing a hydrodesulfurization catalyst which comprises (a) preparing a filter cake of amorphous alumina hydrate at a pH of 7.5-10.5; (b) dewatering the above prepared filter cake by a filter press to raise the Al.sub.2 O.sub.3 concentration to 28-35% by weight and kneading the dewatered filter cake for at least 10 seconds by a self-cleaning type kneader; (c) kneading the dough obtained from the step (b) while adding respective aqueous solutions of water-soluble salts of Group VIB and Group VIII catalyst metals respectively in an amount of 20-60% by weight (as a metal amount) of the total metal amount used at the position just before the entrance of a kneader, kneading the resultant mixture and extruding the kneaded mixture by an extruder; (d) drying and calcining the extrudate; and (e) impregnating the calcined product with salts of remaining catalyst metals in an aqueous ammonia solution and drying and calcining the resultant product.

Abstract: Disclosed is a process of preparing an alumina carrier which comprises kneading an amorphous alumina hydrate, whose alumina concentration is in the range of 28-35 wt. % and which has been obtained by neutralizing an aluminum sulfate solution with a sodium aluminate solution at two stages, while endowing said hydrate with sufficient shearing effect and alternate compression and expansion effect; extruding a resulting dough; drying and calcining the extrudates. According to this process, it becomes possible to control the growth of pseudoboehmite grains contained in the alumina hydrate by controlling the time required for kneading, and accordingly it becomes possible to control the pore distribution of the finally obtained alumina carrier.

Abstract: A method of manufacturing spherical alumina particles which comprises the steps of digesting, at an elevated temperature and an elevated pressure, gibbsite with an aqueous hydrochloric acid solution and then forming an aqueous basic aluminum chloride solution; adding, at an elevated temperature, an aqueous ammonia to said aqueous basic aluminum chloride solution to form an alumina hydrosol containing ammonium chloride; commingling said alumina hydrosol with a gelling agent; thereafter dispersing droplets of said mixture in a suspending medium under conditions effective to transform said droplets into hydrogel particles; ageing said hydrogel particles first in said suspending medium and then in aqueous ammonia; and then washing said hydrogel particles with water, drying and calcining to obtain spherical alumina particles.

Abstract: A method of manufacturing spherical alumina comprising preparing a basic aluminum chloride solution having an aluminum concentration in the range of from 7 wt.% to 12 wt.% and a weight ratio of aluminum to chloride in the range of from 0.3 to 0.8 by reacting gibbsite with an aqueous hydrochloric acid solution at an elevated temperature, preparing an alumina hydrosol having an aluminum concentration in the range of from 9 wt.% to 15 wt.% and a weight ratio of aluminum to chloride in the range of from 0.8 to 1.5 by reacting the thus prepared solution with metallic aluminum at an elevated temperature, commingling this hydrosol with a gelling agent, dispersing the resulting mixture in the form of droplets in a suspending medium thereby to form hydrogel particles, ageing the thus obtained particles in said suspending medium and then an aqueous ammonia, washing with water, drying and calcining. The thus obtained spherical alumina is substantially free from sodium in spite of employing gibbsite as raw material.

Abstract: A catalyst carrier comprising gamma alumina wherein the apparent bulk density is in the range of from 0.65 g/cc to 0.71 g/cc, the total pore volume is in the range of from 0.55 cc/g to 0.65 cc/g, the content of pores having a diameter in the range of from 60A to 110A occupies at least 75% of the total pore volume, the surface area is in the range of from 210 m.sup.2 /g to 250 m.sup.2 /g and the attrition loss is less than 0.5 wt. %. This sort of catalyst carrier can be namufactured through a series of steps of: (a) preparing a first alumina hydrosol having an aluminum concentration in the range of from 9.8 wt. % to 14.4 wt. % and a weight ratio of aluminum to chloride in the range of from 0.95 to 1.20, (b) preparing a second alumina hydrosol having an aluminum concentration in the range of from 9.5 wt. % to 13.0 wt. % and a weight ratio of aluminum to chloride in the range of from 0.85 to 0.

Abstract: Substantially spherical alumina particles are obtained by a process comprising ageing substantially spherical alumina hydrogel particles obtained by the oil-drop method in an ammonium hydroxide solution wherein the concentration of ammonia changes continuously from an initial concentration in the range of from about 0.05 wt.% to about 0.5 wt.% to a final concentration in the range of from about 0.8 wt.% to about 2.5 wt.%. Alumina particles obtained by this process possess improved physical strength. Alumina particles which are obtained by calcining alumina particles aged in an ammonium hydroxide solution, wherein the concentration of ammonia increases continuously, at a temperature in the range of from 650.degree. to 800.degree. C in an atmosphere containing 30 mol.% or more of H.sub.2 O possesses a further improved thermal stability.