Functionalization of carbon xerogels for the preparation of palladium supported catalysts applied in sugar transformations

Carbon xerogels with various pore textures were functionalized by HNO3or air to increase the numberof acidic functions on their surface. These oxidized materials were systematically thermally treated toremove the unstable functions. Analyses indicated that the air treatment was the most efficient becausethe functions created are more numerous, more stable and homogeneously distributed within the sup-port. These surface oxygenated groups were used as anchors for the covalent grafting of the complex[Pd(OAc)2(Et2NH)2] through a ligand exchange mechanism. Activation was carried out thermally to pro-duce supported Pd nanoparticles and led to less sintering compared to a control catalyst prepared on anunmodified support. Catalysts were tested in two different catalytic reactions, namely lactose oxidationand hydrolytic oxidation of cellobiose. The former requires as few surface functions as possible whilethe latter demands a bifunctional catalyst for hydrolysis followed by oxidation. The oxidation of lactosewas more efficient with the catalyst prepared on an unmodified carbon xerogel. On the opposite, thehydrolytic oxidation of cellobiose worked the best with a low loaded catalyst prepared on a functional-ized support, which provided the acidic functions needed for hydrolysis. Moreover, 100% selectivity forgluconic acid was achieved