Adipic ester hydrogenation catalyzed by platinum supported in alumina, titania and pillared clays

Aluminum pillared clay (Al-PILC) and platinum impregnated pillared clay (Pt/Al-PILC) were prepared, characterized and tested as catalysts in adipic ester hydrogenation. Results were compared with those obtained for titania (TiO2) and alumina (gamma-Al2O3) as supports. Results indicate that platinum species are partially occupying the inner porous network of the pillared clay, a solid with an amphoteric character, and these crystallites are small enough to occupy the solid inner micropores. Alumina and Al-PILC supports are active as catalyst, allowing an adipate conversion of 26.3% and 83.3%, respectively, and the products distribution is very influenced by the solid surface acidity. When platinum containing catalysts were tested, the products distribution indicates that reactions of cracking and hydroisomerization, attributed to the acidity of the supports and to the presence of platinum, occur preferentially. However, the reduction in the acidity of Pt/Al-PILC, promoted by a barium bath, allowed the preparation of a catalyst more active and selective than the original catalyst, indicating that the acidity control step is crucial to the performance of this catalyst. (C) 2008 Elsevier B.V. All rights reserved.