PREPARATION OF HYDROXY AL AND AL FE PILLARED BENTONITES FROM CONCENTRATED CLAY SUSPENSIONS/

Aluminum and aluminum/iron pillared clays (PILCs) were prepared starti ng from concentrated (50%) aqueous or acetone suspensions of non-purif ied natural calcium bentonites. The PILCs were characterized by chemic al analysis, X-ray diffraction, magic angle spinning NMR, and N-2 adso rption. The relative amount of Lewis and Bronsted acid sites was estim ated from FT-IR spectra of adsorbed pyridine. All the PILCs prepared b y this method gave highly microporous materials with micropore volumes in the range from 0.11 to 0.15 cm(3)/g, and with highly ordered clay sheets (d(001) = 0.18 nm with peak widths of ca. 0.3 nn). The chemical composition of the products was not influenced by the nature of the s olvent used in the pillaring process. Nevertheless, pillaring in aceto ne resulted in a faster and easier pillaring process. The obtained PIL Cs were more crystalline. The purity of the starting days strongly inf luence the chemical and textural properties of the pillared clay. The scaling up of the process up to 500 g batches using acetone as solvent is easily done and therefore, the method appears attractive for the i ndustrial preparation of aluminum-based PILCs.