ABSTRACT
     The present doctoral thesis employs synthetic and characterization methods on nanoparticulate metallic model catalysts, aiming at elucidating the influence of several structural and physico-chemical features and establishing the basis for the design of new generations of advanced catalysts for the catalytic routes of synthesis gas conversion.
     On one hand, the design and synthesis of monodisperse Co catalysts, using metal colloids in conjunction with nanosized supports, in combination with in situ and operando spectroscopic studies, has allowed to establish a relationship between the non classical structure sensitivity of the Co-catalysed Fischer-Tropsch synthesis (FTS) and the morphological and electronic changes evidenced for the Co nanoparticles under reaction conditions, as a function of the nanoparticle size.
     On the other hand, this work has contributed to rationalize the influence of the thermal history of Co catalysts, from the very early treatments, on the metal surface topology in the final activated catalyst, and its consequences on the intrinsic (per surface metal site) catalytic activity.
     Additionally, on the bases of the gained knowledge, the porous structure of Co-based FTS catalysts has been optimized by a rational design of the catalytic support. In this way, it has been found that both bimodal macro-mesoporous structures as well as mesostructures displaying uniform and short pores lead to catalysts which display enhanced catalytic activity and high selectivity toward middle distillates. 
     Finally, the employment of catalytic supports synthesized by layer-by-layer techniques has allowed to prepare a series of promoted Rh-based catalysts and to study their behavior in the selective synthesis of oxygenate compounds. The present thesis introduces, for the first time, a general interpretation of the role of promoters in this catalytic system, on the basis of a detailed analysis of the electronic properties of the metallic phases and in situ and operando spectroscopic studies.