Abstract: The principal concept behind biorefining involves the transformation of lignocellulosic biomass into valuable products and energy resources. Historically, biorefinery strategies for lignocellulosic biomass have primarily focused on improving the conversion of cellulose into ethanol, often neglecting the underutilized lignin component. Lignin consists of phenolic subunits, from which it follows that value-added products can be obtained from lignin depolymerization. Unfortunately, lignin utilization is particularly challenging due to its high structural irregularity and recalcitrance. The goal of this study was to develop an AuPd/Li-Al layered double hydroxide (LDH) bimetallic catalyst for efficient lignin depolymerization, resulting in the production of high-value aromatic compounds. The structural complexity of lignin renders the study of individual reactions in lignin difficult. Therefore, model compounds were used to evaluate catalyst performance. Initially, we prepared AuPd bimetallic nanoparticles with varying molar ratios supported on a basic Li-Al LDH using a sol-immobilization method. Subsequently, we characterized the synthesized catalysts and evaluated them in aerobic oxidation reactions of 1-phenylethanol and simple benzylic alcohols at atmospheric pressure to identify the most effective catalyst configurations. Those catalysts demonstrating promising performance were further examined in the aerobic oxidation of lignin model dimers containing ß-O-4 linkages. Remarkably, these model compounds underwent sequential oxidation, ultimately leading to the cleavage of the ß-O-4 bonds. Subsequently, we evaluated the catalysts in the oxidative deconstruction of ?-valerolactone (GVL) extracted from maple lignin at 120 °C, again using O2 as the oxidant. These results highlight the potential of the AuPd/Li–Al LDH catalyst system as an eco-friendly approach for lignin depolymerization under mild conditions, offering a promising avenue for valorizing lignin in biorefining processes.

Abstract: Understanding materials at their atomic level is important given that the macroscopic properties of a material are intricately linked to its nanoscale structure. This plays a pivotal role in advancing structural materials since their performance is significantly influenced by factors such as composition, and microstructure which consist of different interfaces, crystalline phases, and defects. 

In the automotive and aerospace industries reducing the weight of materials is critical to enhance fuel efficiency without compromising safety and performance. Lightweight aluminum alloys are extensively studied to replace heavier materials in these sectors. This work offers a comprehensive characterization of the evolution of various precipitates within aluminum alloys under laser treatment conditions, aiming to enhance their mechanical properties.

The thesis also delves into understanding the diffusion and dissolution mechanisms of metal nanoparticles on or into metal oxides. Metals like gold, in their bulk form, are traditionally considered chemically inert and inefficient as catalysts. At the nanoscale, however, as the particle size decreases, their catalytic activity towards various reactions significantly increases. Our exploration of these systems under in situ TEM heating has provided valuable insights into the structure-function relationships of these interfaces. This knowledge can be employed in optimizing the production of nanomaterials with enhanced interface properties.

KEYWORDS: Aluminum alloys, precipitate hardening alloys, SLV, TEM, in situ TEM