부산대학교 도서관

Summary: Hydrogenolysis is one of the most promising lignin valorization processes to produce carbon-neutral sustainable fuels and chemicals from the largest aromatic source on this planet-lignin. Due to its structural complexity, it is extremely difficult to study hydrogenolysis reactions directly on the lignin polymer. Thus, lignin model compounds play a crucial role in lignin chemistry research but, too often, oversimplified models result in misleading and sometimes completely erroneous results. The correct use of authentic lignin models, however, can help predict similar chemistry occurring on the lignin polymer, and further elucidate the reaction mechanisms and kinetics. In this dissertation, lignin chemistry, lignin model compounds, and lignin hydrogenolysis are reviewed. With the aid of lignin model compounds, both fundamental and practical aspects of lignin hydrogenolysis are investigated, under four primary research topics. 1) In a 'lignin-first' approach, an acetalization protection strategy was applied to fractionate lignin from biomass without the lignin condensation problems. Hydrogenolysis of the protected lignin gave a near-theoretical lignin monomers yield. 2) The concept of an "ideal lignin" was developed, and the C-lignin found in native vanilla seedcoat was shown to meet all criteria. Hydrogenolysis of this unique benzodioxane polymer produced a previously inconceivable 90% yield of catechyl monomers in which one monomer predominated by 90% selectivity. 3) A kinetic study was performed on the hydrogenolysis of 棺-ether lignin model compounds in a flow reactor revealing new details of the reactivity of phenolic end-units and etherified internal units in the polymer. A similar kinetic pattern is observed in lignin hydrogenolysis, and high yields of lignin monomers were obtained from real lignins in a continuous flow reactor