Molecularly modified aluminum phosphates as support materials for Ru nanoparticles in selective hydrogenation

Abstract

Modified aluminum phosphate (APO-5) proved suitable as zeotype support for the preparation of imidazolium-based supported ionic liquid phase material, i.e. SILP(APO-5). The successful chemisorption of ionic liquid-like modifiers at the APO-5 surface was demonstrated by solid state ³¹P and ¹³C nuclear magnetic resonance (NMR) spectroscopy. The immobilization of Ru nanoparticles (NPs) on SILP(APO-5) was achieved following an organometallic approach, producing well-dispersed Ru NPs with a mean average size of 1.4 nm on the support. The resulting Ru@SILP(APO-5) material was thoroughly characterized using multiple techniques, e.g., solid state NMR, transmission electron microscopy (TEM), infrared (IR) spectroscopy, X-ray absorption spectroscopy (XAS), and applied as a catalyst for the hydrogenation of biomass-derived furfural acetone with molecular hydrogen. The ionic liquid-like layer was found beneficial for the stabilization of the Ru NPs as well as of the APO-5 material. A temperature-controlled selectivity switch between olefinic, carbonyl or furan ring hydrogenation could be achieved with this new material with the APO-5 facilitating activation of the olefinic bond, while the carbonyl bond was remarkably deactivated. The demonstrated suitability of aluminum phosphate materials to produce molecularly modified surfaces offers a new control parameter for the systematic design and optimization of zeotype-based catalysts.