Chitosan-supported palladium catalyst. 1. Synthesis procedure

Owing to its high sorption capacity for precious metals (especially palladium), the potential of the chitosan biopolymer for catalytic applications was investigated. The catalyst was prepared in two steps: sorption of the palladium, followed by chemical reduction. Two different supports derived from chitosan were tested: a glutaraldehyde cross-linked chitosan and a chitosan derivative that was prepared by preliminary reaction with a sulfate solution (sulfate cross-linking). Three different reduction treatments were tested: treatment with sodium borohydride, treatment with sodium formate, and reduction with hydrogen, which was generated in situ by reacting the material with a sulfuric acid solution in the presence of Zn. The catalytic activity was determined through a very simple reaction: the reduction of chromate in the presence of an electron donor (formate ions).