One-step Conversion of Fructose to Furfuryl alcohol in a Continuous Fixed-bed Reactor: The Important Role of Supports

One-step catalytic conversion of fructose to furfuryl alcohol (FOL) is not only a challenge task but also to open a new pathway for conversion of hexose into useful chemicals. The favorable yield (41.6 %) of FOL can be directly obtained from fructose over the tandem of HY zeolite and Pd/Al2O3. However, the Pd/montmorillonite (Pd/MMT) was deactivated for production of FOL. The proportion of available Pd active sites (i. e. facets, corners and edges) vary with different supports, and the strong metal support interaction (SMSI) plays the pivotal role on the catalytic performance. For Al2O3 support, exposure of Pd (111) plane allows the hydroxymethylfurfural (HMF) to bind on the Pd (111) surface via planar arrangement. In this stance, the aldehyde group of HMF is readily eliminated by decarbonylation. Conversely, for Pd/MMT, the decarbonylation is completely inhibited due to the HMF absorbs on corner sites in perpendicular orientation. The XPS studies indicate that the density electron of Pd nanoparticles (NPs) could be manipulated by various supports, and the electron-donating effect of Al2O3 was observed. The collaborative effects between available sites and density electron of Pd are observed with respect to the different binding modes of HMF on the surface of Pd. The electronegative Pd NPs facilitate the decarbonylation of HMF as a consequence of the different adsorption strength between furan ring and aldehyde group.