Public defence in Chemical Engineering, MSc Gen Li

Title of the thesis: Catalytic conversion of enzymatic hydrolysis lignin: Solvolysis and upgrading

Thesis defender: Gen Li
Opponent: Prof. Chunlin Xu, Åbo Akademi 
Custos: Prof. Tiina Nypelö, Aalto University School of Chemical Engineering

This doctoral thesis focuses on the high-value utilization of enzymatic hydrolysis lignin (EHL), with particular emphasis on its dissolution behavior in solvent systems, depolymerization processes, and catalytic hydrodeoxygenation mechanisms. The objective of this research is to develop a fundamental understanding of how lignin, a major by-product of second-generation bioethanol production, can be efficiently converted into valuable fuels and chemicals. By combining experimental investigations with molecular-level simulations, this work systematically elucidates the interactions between lignin and different solvents and clarifies their roles in promoting lignin disaggregation and conversion. In addition, the reaction pathways of lignin-derived aromatic compounds over nickel-based catalysts are examined in detail, revealing key intermediates and factors governing reaction selectivity. The results demonstrate that rational design of solvent environments and catalytic conditions can significantly enhance lignin depolymerization efficiency and product selectivity. This study provides new insights into the fundamental mechanisms of lignin conversion and offers guidance for the sustainable utilization of lignin in future biorefinery and green chemical processes.

Keywords: Enzymatic hydrolysis lignin, Catalytic upgrading, Solvolysis, Hydrodeoxygenation, Molecular dynamics, Density functional theory

Thesis available for public display 7 days prior to the defence at Aalto University's public display page.