Abstract

DI PRINZIO, Anna  and  NG LEE, Yolanda. Preparation and characterization of catalytic supports y-alumina granulate. Rev. Fac. Ing. UCV [online]. 2008, vol.23, n.4, pp.47-54. ISSN 0798-4065.

The aim of this work is to study the effect of initial hydroxide properties and molding conditions on the desired spherical shape, texture, structure, and mechanical properties of granular alumina (Al₂O₃). The aluminium oxyhydroxide of a pseudoboehmite structure was obtained by precipitation, using as precursors, aluminium nitrate (sample BP) or gibbsite obtained from the Bayer process (sample GL). Two methods were used to prepare the y- Al₂O₃ granules. The first method is based on the snowball effect (production of spheres by rotating dish granulator). The second method is a combination of the sol-gel - oil drop process. Various parameters affecting the granulation process were studied. The results indicated that both the initial characteristics of the aluminium oxyhidroxide and the molding conditions have a great influence on the final properties of the pellets. The method y- Al₂O₃ granular particles prepared by sol-gel - oil drop exhibit better textural and mechanical properties than that of the rotation dish granulation method. The initial crystallinity of the hydroxide had an important effect on the surface area and the resistance of the spherical granules. Poorly crystallized or highly amorphous systems allowed us to obtain granules resistant and high specific surface areas; while the oil drop method affected to the larger degree the form, stability and internal tensions of the pellets.

Keywords : Catalytic support; Oil-drop; Sol-gel; Granulation; y - Al₂O₃ pellets.