New perspectives in nanocatalysis using design of experiments

Identifier:  TDX:2900

Handle: https://hdl.handle.net/20.500.11797/TDX2900

Authors:  Benkirane, Olivia

Abstract:
Heterogeneous catalysts offer an essential tool to achieve a suitable use of energy and chemicals. Indeed, the use of active and selective catalysts in industrial processes can minimize the formation of non-recyclable waste. Among the most commonly applied catalytic processes, the semi-hydrogenation of alkynes into alkenes has been the object of particular attention for its relevance in the petrochemicals, polymer and fine chemical industries. Indeed the selection of proper heterogeneous catalysts derives in productivity improvements preventing over-hydrogenation and/or oligomerization issues. The thesis dealt with the synthesis and characterization of novel catalysts prepared by colloidal approach for application in selective hydrogenation reactions using design of experiments methodology (DOE). Novel synthesis of colloidal Pd NPs was proposed as well as efficient methodologies for the experiment planning, reproducibility demonstration and analytical treatment of TEM data. Two NPs structure-synthesis relationship studies were performed using DOE. The effect of several parameters on the NPs size, distribution, shape and synthesis efficiency were assessed. The key parameters and interactions were highlighted and recipe of well-defined colloidal NPs were delivered. Impregnation of these NPs on different catalytic supports was performed using one pot and two-step syntheses. The effect of the immobilization process, parameter of synthesis, catalytic support, Pd content and scale of the synthesis on the NPs size and dispersion were studied. Finally, a kinetic study of the 1-octyne hydrogenation over four supported catalysts was performed using DOE. The 1-octyne concentration, hydrogen pressure and temperature were varied according to designed experiments: only 24 catalytic tests were performed to obtain robust kinetic expressions for the four catalysts. Thanks to these kinetic data, their performances were compared. This thesis offers a deeper analysis on the design of new Pd-based nanocatalysts for application in alkyne semi-hydrogenation reactions using practical and effective methodologies.