Effect of thermal treatment on the various properties of iron(III)-aluminum(III) coprecipitated hydroxide system

Five samples of Fe2O3-Al2O3 binary system containing 10, 20, 30, 50 and 80 wt.% Fe2O3 were prepared by coprecipitation method, followed by calcination in the temperature range 723-1273 K. The structural characterization was examined by using XRD, DTA and TGA techniques. The textural parameters for the investigated samples, e.g., surface area, total pore volume, mean pore radius and the pore volume distribution, were calculated from the low-temperature nitrogen adsorption isotherms at 77 K. The dehydration and dehydrogenation activities of ethanol, l-propanol, and 2-propanol in samples were followed up with the aid of microcatalytic pulse technique. The assignments of different phases by XRD and DTA techniques revealed the presence of binary system from alpha-Fe2O3 and alpha-Al2O3 as a final product at 1273 K. The inter-conversion between the polymorphic modifications of iron oxide and aluminium oxide was observed at lower temperature. The results also indicated that the textural, acidic properties and the catalytic activities were affected by the thermal treatments and the ratio of iron oxide to aluminium oxide in the prepared samples. (C) 2000 Elsevier Science B.V. All rights reserved.