Highly porous catalytic materials with Pd and ionic liquid supported on chitosan

Abstract

Chitosan was used to immobilize phosphonium-based ionic liquids, combined with silica particles, to prepare catalytic materials in the form of highly porous monoliths. These catalytic materials were studied for the hydrogenation of 4-nitroaniline into p-phenylenediamine in the presence of formic acid as hydrogen donor in a column reactor. Experimental conditions for the elaboration of the materials were evaluated by their impact on palladium sorption, on the structure of the materials, and on their catalytic efficiency. The concentration of chitosan in the initial solution and the size and concentration of silica particles had to be carefully chosen to elaborate homogeneous materials, with good mechanical resistance and stability in water. The chitosan characteristics and the type of ionic liquid immobilized in the material did not significantly affect the structure of the materials but proved to be crucial for their catalytic efficiency. Higher catalytic performances were obtained using materials prepared from chitosan of high-deacetylation degree and with Cyphos IL-101. © 2012 Wiley Periodicals, Inc.