Preparation of hydroxy Al and Al/Fe pillared bentonites from concentrated clay suspensions

Aluminum and aluminum/iron pillared clays (PILCs) were prepared starting from concentrated (50%) aqueous or acetone suspensions of non-purified natural calcium bentonites. The PILCs were characterized by chemical analysis, X-ray diffraction, magic angle spinning NMR, and N-2 adsorption. The relative amount of Lewis and Bronsted acid sites was estimated from FT-IR spectra of adsorbed pyridine. All the PILCs prepared by 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 solvent used in the pillaring process. Nevertheless, pillaring in acetone resulted in a faster and easier pillaring process. The obtained PILCs were more crystalline. The purity of the starting days strongly influence 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 industrial preparation of aluminum-based PILCs.