Characterization and catalytic activity of Cr2O3-Al2O3/AlPO4 catalysts

Five samples of Al2O3/AlPO4 (Al/P = 1.75) and Cr2O3-loaded Al2O/AlPO4 (wt% Cr2O3 = 5-25) were prepared. The catalysts were obtained by thermal treatment of the corresponding samples in air at 823 K and were characterized using XRD and DTA techniques. The textural properties (surface area, total pore volume and mean pore radius) were determined from nitrogen adsorption data obtained at 77 K. The acidic properties of all the samples were measured calorimetrically. The catalytic conversion of isopropanol was studied using a microcatalytic pulse technique. No spinel structure was detected by both XRD and DTA techniques and only Cr2O3 was detected for samples containing greater than or equal to 15 wt% chromia. Loading Al2O3/AlPO4 with Cr2O3 led to significant changes in the texture, surface acidity and catalytic activity of the prepared catalysts. Al2O3/AlPO4 catalysts exhibit no dehydrogenation activity, whereas loading with Cr2O3 favoured the dehydrogenation of isopropanol to acetone.