Influence of support on the aerobic oxidation of HMF into FDCA over preformed Pd nanoparticle based materials

Here, the preparation and evaluation of supported nanoparticle based catalytic material is reported. Polyvinylpyrrolidone (PVP) stabilized palladium nanoparticles with a mean particle size of 1.8 nm were synthesized in ethylene glycol and subsequently deposited onto different metal oxide supports (TiO2, gamma-Al2O3, KF/Al2O3, and ZrO2/La2O3). The prepared catalysts were applied to the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) in aqueous solution at atmospheric pressure (T = 90 degrees C, pO(2) = 1 bar) and compared regarding their catalytic performance and stability. The highest FDCA yield (>90%) was obtained for the Pd/ZrO2/La2O3 catalysts which additionally showed a relatively stable catalytic performance when the material was reused. Various characterization methods including XRD, TEM, XPS, and MS were applied to obtain information about the Pd NP before and after utilization in HMF oxidation. For the Pd/TiO2 the least changes in Pd NP structure were observed after using the material in HMF oxidation. This was attributed to a stronger interaction between the Pd NP and the TiO2 support compared to other supports used in the studies. (C) 2014 Elsevier B.V. All rights reserved.