The world is facing an era of global environmental pollution, as a result of the tremendous population growth and the consequent massive fossil fuel-based energy consumption. A significant exploitation of renewable energies is needed to guarantee quality of human life and allow further sustainable growth, but this may take decades to happen. In order to mitigate the negative effect of human activities on the environment in the short- and mid-term, the development of more efficient technologies for emissions abatement and for renewable fuels production is imperative. Heterogeneous catalysis and photocatalysis are two key pillars of a multi-approach strategy to solve these issues. During the last century, catalysts were explored by changing the formulation of multi-component systems in order to find the best performing material for a certain reaction. Since the late 90's, a new approach to catalytic systems improvement emerged: nano-catalysis. Exploiting the tools of nanotechnology, tailored nanostructured materials can now be produced, which show different properties in comparison to their bulky counterparts, often resulting in better catalytic performances. Furthermore, combining the elements of the periodic table in nano-alloys allows to expand the possibility of catalyst generation. Consistently with these approaches, the main focus of this thesis is the synthesis and characterization of well-defined nanostructured and hierarchical materials for environmental and energy-related applications, such as emissions control, biofuels synthesis and photocatalytic H2 production. We show that structural control at the nanoscale is a great instrument for understanding reaction pathways, for studying the nature of catalytic active sites, and for synthesizing more selective, active and stable catalysts. Two synthetic strategies were followed to acquire nanostructural control: a self-assembly method was employed to prepare hierarchical materials starting from functional nanoparticles, and advanced solvothermal methods were used to prepare monodisperse nanocrystals having controlled size and composition. State-of-the-art hierarchical Pd-based catalysts embedded by metal oxide promoters were tested for methane catalytic oxidation in the presence of poisoning compounds typically found in real applications. Detailed surface studies allowed to propose deactivation mechanisms and strategies to improve catalysts resistance to deactivation. Well-controlled nanostructured Pt-based alloys and Ni-Cu alloys showed improved activity, stability and selectivity for hydrodeoxygenation reactions of biomass-derived feedstocks to produce biofuels. The control of nanostructure was pivotal to understand the reason for such enhanced performances. Finally, dye-sensitized photocatalysts were investigated in H2 photocatalytic production under visible light, and state-of-the-art stability and activities were demonstrated. All these findings greatly contributed to the development of catalytic materials for energy-related applications.

NANOSTRUCTURED MATERIALS FOR ENVIRONMENTAL AND ENERGY-RELATED APPLICATIONS

MONAI, MATTEO
2017-04-26

Abstract

The world is facing an era of global environmental pollution, as a result of the tremendous population growth and the consequent massive fossil fuel-based energy consumption. A significant exploitation of renewable energies is needed to guarantee quality of human life and allow further sustainable growth, but this may take decades to happen. In order to mitigate the negative effect of human activities on the environment in the short- and mid-term, the development of more efficient technologies for emissions abatement and for renewable fuels production is imperative. Heterogeneous catalysis and photocatalysis are two key pillars of a multi-approach strategy to solve these issues. During the last century, catalysts were explored by changing the formulation of multi-component systems in order to find the best performing material for a certain reaction. Since the late 90's, a new approach to catalytic systems improvement emerged: nano-catalysis. Exploiting the tools of nanotechnology, tailored nanostructured materials can now be produced, which show different properties in comparison to their bulky counterparts, often resulting in better catalytic performances. Furthermore, combining the elements of the periodic table in nano-alloys allows to expand the possibility of catalyst generation. Consistently with these approaches, the main focus of this thesis is the synthesis and characterization of well-defined nanostructured and hierarchical materials for environmental and energy-related applications, such as emissions control, biofuels synthesis and photocatalytic H2 production. We show that structural control at the nanoscale is a great instrument for understanding reaction pathways, for studying the nature of catalytic active sites, and for synthesizing more selective, active and stable catalysts. Two synthetic strategies were followed to acquire nanostructural control: a self-assembly method was employed to prepare hierarchical materials starting from functional nanoparticles, and advanced solvothermal methods were used to prepare monodisperse nanocrystals having controlled size and composition. State-of-the-art hierarchical Pd-based catalysts embedded by metal oxide promoters were tested for methane catalytic oxidation in the presence of poisoning compounds typically found in real applications. Detailed surface studies allowed to propose deactivation mechanisms and strategies to improve catalysts resistance to deactivation. Well-controlled nanostructured Pt-based alloys and Ni-Cu alloys showed improved activity, stability and selectivity for hydrodeoxygenation reactions of biomass-derived feedstocks to produce biofuels. The control of nanostructure was pivotal to understand the reason for such enhanced performances. Finally, dye-sensitized photocatalysts were investigated in H2 photocatalytic production under visible light, and state-of-the-art stability and activities were demonstrated. All these findings greatly contributed to the development of catalytic materials for energy-related applications.
FORNASIERO, Paolo
29
2015/2016
Settore CHIM/06 - Chimica Organica
Università degli Studi di Trieste
File in questo prodotto:
File Dimensione Formato  
Monai_PhD_thesis_low res.pdf

accesso aperto

Descrizione: tesi di dottorato
Dimensione 5.17 MB
Formato Adobe PDF
5.17 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2908133
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact