Abstract

GUERRA, D. L.; LEMOS, V. P.; ANGELICA, R. S.  and  AIROLDI, C.. Influence of the Al /clay ratio on the pillaring process of smectite. Cerâmica [online]. 2006, vol.52, n.323, pp. 200-206. ISSN 0366-6913.  http://dx.doi.org/10.1590/S0366-69132006000300014.

Smectite-type clays from the state of Pará, Brazil, were characterized by XRD, ²⁷Al MAS NMR, FTIR and textural analysis by nitrogen adsorpition-desorption isotherms. In the production of pillared clays, the Al₁₃ ion (keggin's ion) was used. This ion was obtained by the reaction of AlC_l36H₂O/NaOH solutions with OH/Al=2 molar ratio and with Al/clay ratios of 5, 10, 15, 20, 25 meq/g of clay, intercalated at 25 ºC during 3 h and calcined at 450 ºC (adequate temperature for calcination). The results showed that the pillarization process increased the basal spaces of the natural clay from 14.02 to 18.84 Å and the surface area from 44.30 to 198.03 m²/g (Al/g of clay = 25 meq/g of clay, pH=4). Materials prepared with different Al/g clay ratio showed the maximum Al incorporation for Al/g of clay = 25 meq/g of clay. The thermal stability of the natural clay was improved by the pillaring procedure.

Keywords : pillared clay; Al₁₃; smectite.