Mg/Al hydrotalcites: preparation, characterisation and ketonisation of acetic acid

Mg/Al hydrotalcites with different Mg:Al ratios were prepared and characterized by PXRD, FTIR, TG/DTA, basic sites and nitrogen adsorption-desorption methods. It is confirmed from PXRD that the materials have hydrotalcite structure. The basic sites of the samples were determined spectrophotometrically by irreversible adsorption of acids having different pK(a) values which showed that the basic sites increases with increase in Mg:Al ratio. The specific surface area of all samples Lies in the range 170-231 m(2)/g. All the samples were predominantly mesoporous in nature and pore diameters lie in the range 40-70 Angstrom. The sample with Mg:Al ratio of 4:1 showed highest specific surface area and conversion (> 86.5%) of acetic acid to acetone with high selectivity at 350 degrees C. (C) 2000 Elsevier Science B.V. All rights reserved.