No abstract

No 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) × nH 2 O, Ru(0), and [RuO 4 ] 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.

Here we report novel catalysts for nitrobenzene hydrogenation based on Ru/RuO 2 nanoparticles (NPs) and including iron oxide NPs, allowing magnetic recovery. The solvent type, reaction temperature, and the size and composition of initial iron oxide NPs are demonstrated to be the control factors determining synthesis outcomes including the degree of NP aggregation and catalytic properties. A complete characterization of the catalysts using transmission electron microscopy (TEM), X-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and energy dispersive x-ray spectroscopy (EDS) allowed assessment of the structure-property relationships. It is revealed that coexistence of the Ru/RuO 2 and iron oxide NPs in the catalyst as well as the proximity of two different NP types lead to significantly higher aniline yields and reaction rates. The catalytic properties are also influenced by the type of iron oxide NPs present in the catalytic samples.

No abstract

No abstract

Here, we report on the development of novel Zn-, Zn-Cr-, and Zn-Cu-containing catalysts using magnetic silica (FeO-SiO) as the support. Transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) showed that the iron oxide nanoparticles are located in mesoporous silica pores and the magnetite (spinel) structure remains virtually unchanged despite the incorporation of Zn and Cr. According to XPS data, the Zn and Cr species are intermixed within the magnetite structure. In the case of the Zn-Cu-containing catalysts, a separate CuO phase was also observed along with the spinel structure. The catalytic activity of these catalysts was tested in methanol synthesis from syngas (CO + H). The catalytic experiments showed an improved catalytic performance of Zn- and Zn-Cr-containing magnetic silicas compared to that of the ZnO-SiO catalyst. The best catalytic activity was obtained for the Zn-Cr-containing magnetic catalyst prepared with 1 wt % Zn and Cr each. X-ray absorption spectroscopy demonstrated the presence of oxygen vacancies near Fe and Zn in Zn-containing, and even more in Zn-Cr-containing, magnetic silica (including oxygen vacancies near Cr ions), revealing a correlation between the catalytic properties and oxygen vacancies. The easy magnetic recovery, robust synthetic procedure, and high catalytic activity make these catalysts promising for practical applications.

No abstract