Abstract: A process for producing catalysts for hydrotreating petroleum fractions, said catalysts containing, after thermal treatment, at least an oxide or a sulphide of a Group VIII metal and at least an oxide or a sulphide of a Group VI B metal and an alumina support, said process comprising preparing said catalyst in the form of beads by agglomeration of alumina by polymerizing, in a hot substantially water-immiscible fluid medium, an aqueous mixture consisting essentially of alumina hydrogel and a water-soluble monomer whose uncrossed-linked polymer is water-soluble or forms a gel, and thereafter dispersing said aqueous mixture in the form of droplets, into said fluid medium in which substantial polymerization of the monomer is carried out.

Abstract: A process for preparing silico-alumina beads containing silica and at least an equal amount of alumina comprising dispersing as droplets into a hot and practically water-immiscible fluid, an aqueous mixture which comprises alumina hydrogel, alumina hydrosol as alumina precursors, an alkali silicate and silica gel as silica precursors, the amount of alkali silicate, based on SiO.sub.2, not exceeding 20% of the total weight of SiO.sub.2 and Al.sub.2 O.sub.3, and the total amount of alkali silica and silica gel, based on SiO.sub.2, not exceeding 50% of the total weight of SiO.sub.2 and Al.sub.2 O.sub.3, and at least a water-soluble monomer whose uncross-linked polymer is water-soluble or forms a gel, and maintaining the droplets of the aqueous mixture in the hot fluid until substantial polymerization of said monomer occurs.

Abstract: A process for preparing spheroidal silica-alumina particles containing alumina in an amount at least equal to that of silica, comprising dispersing as droplets into a hot and practically water-immiscible fluid, an aqueous mixture comprising an alkali silicate, alumina hydrogel, perchloric acid and a water-soluble monomer whose uncross-linked polymer is water-soluble or forms a gel, alkali silicate and alumina hydrogel being used in proportions corresponding to 0.5 to 50% by weight of SiO.sub.2 and 99.5 to 50% by weight of Al.sub.2 O.sub.3, and maintaining the droplets of the mixture in the fluid until a substantial polymerization of the monomer occurs.

Abstract: A process for preparing catalysts in the form of beads comprising at least a catalytic agent and an alumina carrier, said process comprising polymerizing in a hot and substantially water-immiscible fluid, an aqueous mixture which comprises alumina hydrogel, alumina hydrosol and a compound capable of generating a catalytic agent and a water soluble monomer whose uncross-linked polymer is water soluble or forms a gel, such aqueous mixture being dispersed as droplets into the hot fluid, recovering beads from said water-immiscible fluid and drying and calcining said beads.

Abstract: A process for producing catalysts to hydrotreat petroleum fractions containing, after thermal treatment, an oxide or a sulphide of a Group VIII metal and an oxide or a sulphide of a Group VI B metal and a support consisting essentially of alumina, said process comprising preparing said catalyst in the form of beads by agglomeration of alumina by polymerizing in a hot and substantially water-immiscible fluid, an aqueous mixture which consists essentially of alumina hydrogel, alumina hydrosol and a water-soluble monomer whose uncrossed-linked polymer is water-soluble or forms a gel and then by dispersing said mixture as droplets, in a polymerization zone.

Abstract: A process for preparing spheroidal catalyst particles having an alumina support, which comprises polymerizing, in a substantially water-immiscible, hot fluid medium, an aqueous mixture which comprises alumina hydrogel, a compound capable of generating an active catalytic agent and a water soluble monomer whose uncross-linked polymer is water soluble or forms a gel, said aqueous mixture being dispersed in the form of droplets into the hot fluid medium wherein substantial polymerization of said monomer is performed.

Abstract: A process for preparing aluminium oxide beads from alumina hydrogel, which comprises polymerizing, in a hot and substantially water-immiscible fluid, an aqueous mixture comprising alumina hydrogel and alumina hydrosol and a water-soluble monomer whose uncross-linked polymer is water-soluble or forms a gel, this mixture being dispersed as droplets into a hot fluid in which substantial polymerization of the monomer occurs.

Abstract: A process for preparing aluminum oxide beads from alumina hydrogel, comprising polymerizing in a hot and substantially water-immiscible fluid, an aqueous mixture which contains alumina hydrogel and a water soluble monomer whose uncross-linked polymer is water soluble or forms a gel, this mixture being dispersed as droplets into said fluid in which substantial polymerization of said monomer is performed.