Preparation of catalysts of predetermined pore size distribution and pore volume

Claim 1

In a process for preparing an alumina for subsequent incorporation with a Group VI-B or Group VIII metal, or both, or alumina precipitated as a hydrogel cogelled with a Group VI-B or Group VIII metal, or both, to form a catalyst, the alumina being precipitated as an alumina hydrogel from a solution which contains a hydrous form of alumina and an anion soluble in an alkaline medium and which forms a soluble aluminum salt, the hydrogel of alumina being precipitated from a solution which contains alumina in concentration ranging from about 1 to about 5 percent, based on the weight of solution, at pH ranging from about 8 to about 12, and at temperatures ranging from about 15° F. to about 120° F., the alumina hydrogel being separated from the solution, the alumina hydrogel being contacted with a solution of a water soluble polymer containing from about 2 to about 24 monomer units from the group consisting of (a) polyethylene glycols, (b) polypropylene glycols, and (c) polyethylene amines sufficient to absorb the polymer into the pores of the alumina hydrogel and displace water from the pores until the weight ratio of polymer:alumina within the hydrogel ranges from about 0.5:1 to about 4:1, the hydrogel being dried, and then calcined to form gamma alumina, the catalyst composite which includes the Group VI-B or Group VIII metal, or both, being characterized, when the catalyst is of size ranging from about 1/50 inch up to 1/25 inch average particle size diameter, as having at least about 15 percent of its total pore volume of absolute diameter within the range of about 150A to about 250A; when the catalyst is of size ranging from about 1/25 inch to about 1/8 inch average particle size diameter, as having at least about 15 percent of its total pore volume of absolute diameter within the range of about 175A to about 275A; and wherein, in each of these catalysts of differing ranges of particle size distributions, the pore volumes resultant from pores of 50A, and smaller, are minimized; the surface areas and pore volumes of the catalysts being interrelated with particle size, and pore size distributions, surface areas ranging at least about 200 m 2 /g to about 600 m 2 /g with pore volumes ranging from about 0.8 to about 3.0 cc/g (B.E.T.), the improvement comprising contacting, and peptizing the hydrogel of alumina after its precipitation from said solution, and prior to the time that it is calcined and transformed into gamma alumina with an aqueous solution of a monocarboxylic or polycarboxylic acid.