ABSTRACT
    
    
    The present doctoral thesis presents a study on the synthesis and characterization of V- and Mo-containing mixed metal oxide bronzes to be used as catalysts in partial oxidation reactions of light alkanes (C2-C4), such as oxidative dehydrogenation of ethane, and especially for the selective oxidation of propane to acrylic acid.
    
    Ternary mixed metal oxides Mo-V-X (X= different metals) have been prepared hydrothermally, obtaining effective catalysts in the partial oxidation of propane to acrylic acid only in the case of Sb- and Te- containing materials. Then, the influence of synthesis parameters and the incorporation of promoters have been also studied in the catalytic behavior of those materials. The results shows that the presence of reducing agents and/or the incorporation of promoters (niobium or alkali metals) in the synthesis gel, as well as the activation procedure and the post-synthesis modifications (selective incorporation of promoters or the treatment of solids with aqueous solutions of H2O2), can improve the catalytic behavior of these materials.
    The physico-chemical characteristics of catalysts have been determined by using several spectroscopic techniques (i.e. IR, UV-vis, Raman, XPS, EPR, XAS), XRD, electron microscopy (SEM/TEM/HRTEM), and the analysis of the surface acid characteristics (TPD-NH3). 
    Combination of catalytic and characterization results has allowed the determination of key aspects in the synthesis and modification of catalysts. This has allowed the development of new materials, with the same crystalline structure, but improving substantially their catalytic behavior. In this way, yields of acrylic acid (from propane) or ethene (from ethane) higher than those achieved over ternary metal oxides has been achieved.
    Additionally, the most representative catalysts prepared in the present research have been tested in the selective oxidation of n-butane showing very interesting results. The optimal catalyst has achieved productivity to maleic anhydride higher than that obtained with a conventional V-P-O industrial catalyst. Unfortunately, the selectivity to maleic anhydride is still higher for the V-P-O catalyst.
    
    Finally, and from the comparative study of the partial oxidation of ethane, propane and n-butane, as well as from the in situ analysis, by infrared spectroscopy, about the evolution of reaction intermediates adsorbed over those materials; the present thesis proposes some of the key aspects to be considered in the development of particularized and efficient catalytic systems according to both the reactant and the reaction product desired.