Defence H. Yang: "Biobased Aromatic Chemicals by Lignin Depolymerization and Defunctionalization"

Promotors: Prof. H.J. Heeres & Prof. P.J. Deuss

Abstract: Nowadays, the production of chemicals is heavily dependent on fossil resources. Alternatives are required for sustainable development, and the use of renewable carbon sources such as biomass is an attractive option. In particular, lignin is interesting for this purpose, as currently, it is mainly used for energy generation and thus highly underutilized. Due to its aromatic structure, lignin can serve as a renewable resource to produce aromatic chemicals, especially phenolics. In this PhD research, experimental studies were performed with the objective to valorize technical lignins to biobased aromatic chemicals with an emphasis on phenolics. Catalytic hydrotreatment played a central role throughout the research. It entails a treatment of the lignins with molecular hydrogen in combinaton with a catalyst at elevated temperatures and pressures. New non-precious metal catalysts (e.g., Ni, MoO3, and Cu catalysts) were developed for the purpose of obtaining high yields of the desired low molecular weight phenolic products, and particularly their long-term stability was evaluated. Besides catalyst development, a pretreatment method combined with hydrotreatment and an integrated approach (pyrolysis + staged condensation + hydrotreatment) were investigated in detail for improved phenolic yields. The research described in this thesis provides new insights and solutions for producing bio-based phenolics from lignin.

Dissertation