Manuel Fernando Ribeiro Pereira

Currently, the transportation sector represents about one third of the total energy consumed in the world, most of this energy being obtained almost exclusively from oil. However, the world is changing, as well as the aviation industry. Since lignocellulosic biomass is a low-cost feedstock that does not compete with food, it has drawn great attention as one of the most attractive alternatives to replace fossil feedstocks for the production of fuels. Renewable jet fuels could have a significant impact on lowering greenhouse gas emissions and providing a long-term sustainable alternative to petroleum-derived fuels. However, the catalytic upgrading of lignocellulosic residues in industry still remains a big challenge and the development of highly integrated systems that allow the direct conversion of lignocellulosic wastes is essential to achieve that goal. The importance of renewable jet fuels and the potential of lignocellulosic biomass have already been extensively reviewed. However, this work presents a new perspective on the main catalytic routes and challenges for the sustainable production of aviation fuels from biomass wastes.

Nitrate catalytic reduction in a continuous system was studied in the presence of Pd-Cu macrostructured catalysts synthesized through a novel washcoating methodology of the pre-formed bimetallic powder catalyst. The present work aims to understand the behavior of the macrostructured bimetallic catalyst in the presence of different reaction conditions in order to achieve the design of an optimized facility that can produce the best catalytic results: maximum NO3− conversion with enhanced N2 selectivity. The residence time of the inlet solution and the catalyst concentration in the reactor proved to be the parameters that most influenced the conversion and selectivity due to the important role that these parameters play in the hydrodynamic conditions of the reactor. A higher loading of catalyst and lower inlet flow rates allow promoting a higher contact time between the three phases that participate in the reaction (G-L-S). The most efficient reaction conditions (three pieces of the macrostructured catalyst, liquid flow rate of 10 mL min−1, and a total gas flow rate of 200 Ncm3 min−1 (1:1 H2:CO2)) allowed obtaining an NO3− conversion of 51% with a corresponding N2 selectivity of 23%. Also, the conversion results strongly depended on the total gas flow rate used during the reaction since this assists the mixing between the three phases and promotes a greater contact that will contribute to enhanced catalytic results.