Date of Award
Fall 2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Anastas, Paul
Abstract
Due to the concerns over the global environmental impact of fossil fuel use, the conversion of renewable biomass to fuels and useful chemicals has attracted increasing attention. Lignin has emerged as a promising candidate due to its unique aromatic backbone structure and its natural abundance coupled with its underutilization as a feedstock. The growing interest in lignin as a renewable feedstock for aromatic platform chemicals has led to increased research efforts into its valorization, particularly through controlled depolymerization into smaller aromatic building blocks. One of the most common bonds in lignin’s complex structure is the C-O bond, and these bonds are often characterized by their positions with regard to the aromatic structures present in lignin (e.g., α-O-4, β-O-4, or 4-O-5 linkages). Therefore, the effective cleavage of C-O bonds in aromatic ethers is highly relevant to achieve lignin depolymerization. Such depolymerization is complicated by several factors, which include the relatively high activation barrier for aromatic C-O bond cleavage, site selectivity of the various C-O bond linkages within lignin, and the competing hydrogenation reaction of the aromatic rings. Existing approaches for lignin depolymerization through catalytic hydrogenolysis of lignin’s plentiful C-O bonds often require a noble metal catalyst and/or harsh conditions such as elevated temperatures and high pressures. On the other hand, electrocatalytic hydrogenation presents an attractive alternative as a greener technology due to its milder reaction conditions, better control of product selectivity, and energy feasibility when integrated with renewable electricity sources. Therefore, the presented thesis aims to develop effective and selective electrocatalytic methods using abundant metals for C-O bond cleavage with a focus on α-O-4 linkages, represented by the model compound benzyl phenyl ether. Because α-O-4 linkages account for ~50% of all C-O bonds in C-lignin, it has recently gained increasing attention as a “simpler” renewable feedstock.
Recommended Citation
Lin, Fang, "Greener Routes to Biomass Valorization: Lignin Upgrading using Electrochemical Method" (2023). Yale Graduate School of Arts and Sciences Dissertations. 1136.
https://elischolar.library.yale.edu/gsas_dissertations/1136
