Hydrogénation sélective du crotonaldéhyde sur des catalyseurs au platine et au ruthénium supportés sur oxyde d'étain

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Immobilization of Methyltrioxorhenium on Mesoporous Aluminosilicate Materials

The presented report focuses on an in-depth detailed characterization of immobilized methyltrioxorhenium (MTO), giving catalysts with a wide spectra of utilization. The range of mesoporous materials with different SiO2/Al2O3 ratios, namely mesoporous alumina (MA), aluminosilicates type Siral (with Al content 60%–90%) and MCM-41, were used as supports for immobilization of MTO. The tested support materials (aluminous/siliceous) exhibited high surface area, well-defined regular structure and narrow pore size distribution of mesopores, and therefore represent excellent supports for the active components. Some of the supports were modified by zinc chloride in order to obtain catalysts with higher activities for instance in metathesis reactions. The immobilization of MTO was optimized using these supports and it was successful using all supports. The success of the immobilization of MTO and the properties of the prepared heterogeneous catalysts were characterized using X-ray Fluorescence (XRF), atomic absorption spectroscopy (AAS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), physical adsorption of N2, ultraviolet-visible spectroscopy (UV-Vis), infrared spectroscopy (FTIR), Fourier Transform Infrared Spectroscopy (FTIR) using pyridine as a probe molecule and X-ray photoelectron spectroscopy (XPS). Furthermore, the catalytic activity of the immobilized MTO on the tested supports was demonstrated on metathesis reactions of various substrates

Application of molecular modelling in heterogeneous catalysis research

Traditionally, heterogeneous catalysis has largely been an experimental field. While this is still true today, it is increasingly recognized that computer modelling and simulation are important tools in the study and development of catalytic systems. Molecular modelling has the potential to provide new insights into reaction pathways, to predict properties of catalysts that have not yet been synthesized, and to bring information for a given system from many different experimental techniques into a coherent picture. A close interaction of modelling and experiment is vital. The most fruit-fully strategy for using modelling in catalysis research is likely to be a dual-feedback mode, where experiments (kinetic studies of reaction rates, thermodynamic information on adsorption, and spectroscopic data on molecular-level structure) are used to validate the modelling and modelling is used to explain experimental results, to suggest new experiments, and perhaps to substitute for experiments in the screening of different catalysts or reaction conditions. The objective of this work is to present the dual-feedback mode on three case studies from the branch of heterogeneous catalysis and to highlight some interesting outputs as a result of applying such approach. The first issued from the study of molecular structure effects on noble metal catalyst. It presents usefulness of such approach for probing the mechanism of surface processes in hydrogenation of CC unsaturated bonds. The second one demonstrates how could theoretical calculations help in characterizing of active site in cinchona modified platinum catalyst and also judged the mechanism theories in stereoselective hydrogenations. The last case study presents a possibility to predict properties of hydrotalcite catalyst used for aldolization of cyclic ketones before its synthesis and also to define its applicability