Spray-drying for the preparation of Al–Co–Cu pillared clays: A comparison with the conventional hot-drying method

This work reports the synthesis of pillared clays with Al, Al–Co, Al–Cu, and the new ternary system Al–Co–Cu. Natural clay (bentonite) was intercalated with aqueous metal-ion polyhydroxycationic solutions and further dried by either conventional oven-drying or spray-drying. The two drying methods were compared to optimize the pillaring process. The obtained powders were characterized by different techniques, revealing several advantages and an enormous reduction in the process time with spray-drying. X-ray powder diffraction, X-ray fluorescence, and nitrogen adsorption analyses showed successful pillaring of the solids. Textural analyses showed higher surface areas and larger pore volumes for spray-dried pillared clays. Comparable thermal behavior (TGA-DSC analyses) was observed for pillared solids obtained by both drying methods. Scanning electron microscopy (SEM) revealed better control of particle size and shape when spray-drying was used.