Kinetics of Lactose Hydrogenation over Ruthenium Nanoparticles in Hypercrosslinked Polystyrene

Abstract

Lactose hydrogenation is a complex chemical process characterized by formation of numerous side products. Therefore, the synthesis of efficient catalysts for lactose hydrogenation and the investigation of the kinetics of this process are important for increasing of lactitol yield. Synthesis of nanocatalysts based on ruthenium-containing nanoparticles (NPs) formed in the pores of hypercrosslinked polystyrene (HPS) modified with amino groups and their catalytic properties in the lactose hydrogenation are described in the current work. The Ru species were incorporated in HPS using wet impregnation of ruthenium(IV) hydroxychloride followed by reduction with hydrogen at 300 °C. The catalysts containing from 1.1 wt % to 4.9 wt % of Ru were studied by X-ray fluorescence analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, CO chemisorption, and liquid nitrogen physisorption methods. It was demonstrated that the NP sizes are controlled by the HPS pores. Several types of Ru species, Ru(IV), Ru(IV) × nH2O, Ru(0), and [RuO4]2– constituted the NP composition. The kinetics model developed is based on the concept of noncompetitive adsorption of hydrogen and organic molecules, because of the large difference in the sizes of sugar molecules and hydrogen, describing the experimental data well. The distribution and sensitivity of the parameters obtained were checked with the Markov–Chain Monte Carlo method.