Development of innovative processes and catalysts for the valorisation of Bio-Oil

Hydrothermal liquefaction (HTL) is a process for converting waste biomass to bio-oil by contacting the biomass with water at high temperatures and sufficient pressures in order to keep the water in the liquid state. HTL process is energy efficient and capable of dealing with wet biomass, such as sorted domestic organic waste, sewage sludge, algae, etc. However, HTL oils contain high contents of oxygen and nitrogen because of the initial biomass composition. Therefore, the bio-oil has to be upgraded in order to produce advanced transport fuels. Information regarding the nitrogen compounds present in bio-oil is of major concern of any hydrotreatment, since the low hydrodenitrogenation rate and catalyst poisoning by nitrogen compounds make this process expensive. Therefore, the main goal of the present study is the investigation of the HTL reaction mechanism, focusing the attention on the nitrogen containing species pathways, with the goal to increase the energy yields and reduce the nitrogen content in the produced bio-oil. Due to the complexity of the biomass composition, model compounds that encompass all the biochemical components of biomass, namely proteins, lipid and carbohydrates, are emerged to unravel the main chemical reaction pathways existing between macromolecular components. Moreover, several microbial biomass types, such as oleaginous yeast and liamocins, were also treated via HTL. The whole study helps to better understand the HTL of organic waste biomass and microbial biomass/oils, providing useful insights into the reaction products, pathways, and mechanisms for the production of bio-oils and chemicals.