Advanced catalysts for a low-carbon future exploring new routes for biomass valorisation 291

Biomass valorisation is becoming an appealing topic considering the gradual depletion of fossil fuel and the severe environmental deterioration aroused from the massive emission of greenhouse gases (GHGs). Deoxygenation is a fundamental reaction in the upgrading of bio-oil to produce hydrocarbon fuels or high-value chemicals. The removal of oxygen in bio-oil could increase the heating value, enhance the thermal and chemical stability, reduce corrosivity, etc. making the upgraded bio-oil suitable as fuel or blending fuel. Hence, in this thesis, the deoxygenation of raw bio-oil and hydrodeoxygenation of bio-oil model compounds are investigated. Pt/NC are proven to be effective catalysts for the deoxygenation of palm oil to produced bio-hydrogenated diesel (BHD) under optimised reaction conditions. The enhanced interaction between reactants and nitrogen doped support (NC) explains the higher decarbonylation and/or decarboxylation (DeCOx) selectivity. The hydrodeoxygenation of guaiacol with H2 generated from aqueous phase reforming (APR) of methanol and glycerol is conducted in a high-pressure batch reactor. Higher conversion is achieved for methanol as hydrogen source, owing to the higher H2 selectivity from APR process. The interaction of Ni and Pt could enhance the dehydroxylation and hydrogenation in the HDO process, and thus promote deoxygenation efficiency for HDO using methanol as hydrogen source. A novel method for “H2-free” HDO suppressing the external H2 supply is proposed and this concept feasibility is tested over carbon supported non-noble and noble metal catalysts. There is still a large room for improvement in terms of deoxygenation efficiency, but the proposed HDO method is highly recommendable opening new cost-effective alternative for the biomass valorisation. It is worth emphasising the hydrogen transfer route is investigated by the analysis of gas products and the distribution of isotope in isotopic labelling analysis. D/H transfer happens in the catalytic HDO process evidencing the role of the hydrogen donor to produce H2 in-situ. Overall, this thesis showcases appealing strategies for biomass valorisation and how an optimal catalyst design is vital to unlock the potential of bio-resources. In fact, this work is conceived to serve as guidance for the successful design of advanced catalysts to pursue a low carbon future as ultimate goal