High apparent bulk density gamma alumina carrier and method of manufacture of same

A method of manufacturing a catalyst carrier consisting essentially of substantially spherical gamma alumina particles having an apparent bulk density in the range of from 0.65 g/cc to 0.71 g/cc, a total pore volume measured by the nitrogen adsorption method in the range of from 0.55 cc/g to 0.65 cc/g, a content of pores having a diameter in the range of from 60 Angstroms to 110 Angstroms of at least 75% of the total pore volume, a surface area measured by the nitrogen adsorption method in the range of from 210 m.sup.2 /g to 250 m.sup.2 /g, and an attrition loss of less than 0.5 wt.%, which comprises the 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) then adding hydrochloric acid to said first aluminum hydrosol in proportions effective to form 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 0.95,
• (c) then commingling said second alumina hydrosol with a gelling agent which is hydrolyzable at an elevated temperature wherein the amount of said gelling agent is from 1.65 to 1.85 times the chemical equivalent necessary to neutralize the chloride contained in said second alumina hydrosol and thereby obtaining a mixture having an aluminum concentration in the range of from 6.0 wt.% to 7.0 wt.%, and
• (d) then dispersing said mixture as droplets in a suspending medium under conditions effective to transform said droplets into hydrogel particles, ageing said hydrogel particles in said suspending medium and then in aqueous ammonia, then washing said hydrogel particles with water, then drying and then calcining said hydrogel particles to obtain said gamma alumina particles.