Chemistry Aimed at Upgrading Lignin
Dimitris S. Argyropoulos, PhD, Department of Chemistry & Forest Biomaterials, North Carolina State University
Lignin is the second in abundance component of woody plants with a highly branched and irregular structure. This material represents an integral component of the actual paper manufacturing process, since it is incinerated to recover energy and chemicals. Technical ligninsources represent potential market opportunities due to their aromatic nature and their vast daily supply. In this respect, only a small part of it is isolated from spent pulping liquor and eventually commercialized at a scale of about 1 million tons per year. Obviously such streams represent a promising renewable alternative for the creation of aromatic chemicals, monomers and eventually polymers. In an effort to unravel the potential of this material in becoming a source of such chemicals we examined the catalytic cleavage of many of its critical linkages. We aimed at creating the foundations for the development of catalysts for ether bond cleavage via the aerobic activation of C-O bonds using iridium complexes. In addition, extensive studies on different methods for oxidative olefin cleavage within technical softwood kraft lignin were carried out. Finally and since vanillin was the main product of our oxidations, we created model monomers which were then coupled with lignin in polymerization reactions offering polymers with promising properties. These efforts that represent a synergistic relation between NSF and IRI are described during this presentation.