Characterization and Catalytic Activity of Cr 2 O 3 –Al 2 O 3 /AlPO 4 Catalysts

Abstract

Five samples of Al₂O₃/AlPO₄ (Al/P = 1.75) and Cr₂O₃-loaded Al₂O₃/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 ≥ 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.