PhD Defence Jessi Osorio Velasco: "Biomass to chemicals and fuels using advanced thermochemical concepts"

Promotors: Prof Erik Heeres, Prof Jun Yue

Abstract: Dwindling fossil carbon sources drive the need for the valorisation of renewable alternatives to produce fuels and chemicals. Lignocellulosic biomass is a promising renewable feedstock and is widely studied for its conversion into fuels and chemicals (e.g. through pyrolysis or hydrotreatment). Some challenges in biomass valorisation are the efficiency and cost-effectiveness of existing processes and the complexity of the product that often consists of a wide variety of chemicals requiring additional purification steps. In this thesis, two advanced thermochemical strategies to valorise biomass into high quality chemicals are described: i) pyrolysis with molten salts and ii) catalytic hydrotreatment. The use of molten salts in pyrolysis enhances monomeric product yields. A staged free-fall reactor is presented for (catalytic) pyrolysis of lignocellulosic biomass with demonstrated efficacy in the lab processing of pinewood sawdust. The presence of molten salts significantly influenced thermal behaviour during pyrolysis, due to catalytic effects of the salts the formation of key products, like guaiacols, was promoted. Hydrotreatment of technical lignins without solvent using NiMoP catalysts on various supports yielded promising results. A highest monomer yield of 51.8 wt% was obtained with the SiO2-supported catalyst. Support acidity, as well as the interaction of the catalyst with different lignin sources were crucial factors influencing the obtained monomer yields. In summary, the research describes novel findings on biomass conversion using advanced thermochemical concepts, which will aid in the future development of innovative strategies for the efficient valorisation of biomass into valuable fuels and chemicals.

Dessertation