2024 AIChE Annual Meeting

(573g) Redefining Lignin Valorization By Integrating Chemical Depolymerization and Microbial Funneling to Produce Specialty Bioproducts

Authors

Sripada, S. - Presenter, DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison‘ and ’Wisconsin Energy Institute, University of Wisconsin-Madison
Scholz, S., University of Wisconsin Madison
Qualls, A., University of Wisconsin Madison
Garcia, M. A., University of Wisconsin Madison
Kim, B., University of Wisconsin Madison
Donohue, T. J., University of Wisconsin-Madison
Noguera, D. R., University of Wisconsin-Madison
Karlen, S. D., UW-Madison
Sener, C., University of Wisconsin - Madison
To improve the sustainability and economics of lignocellulosic biorefineries, there has been a growing interest in upgrading lignin into bioproducts and specialty biofuels through integrated chemical and biological processes. We have developed a biomass-to-bioproduct pipeline that involves chemical fractionation and depolymerization of biomass by catalytic hydrogenolysis followed by microbial funneling (using an engineered microbe Novosphingobium aromaticivorans) of depolymerized lignin to produce 2-pyrone-4,6-dicarboxylic acid (PDC), a precursor for bioplastics.

This pipeline used reductive catalytic fractionation (RCF) to fractionate lignocellulosic biomass and depolymerize lignin into a mixture of monomeric and oligomeric phenolic compounds. The RCF process used methanol as a solvent to fractionate lignin from cellulose and hemicellulose and a Pd/C catalyst with hydrogen to reductively depolymerize the lignin. A solid carbohydrate pulp was obtained, which can be further upgraded into biofuel. The solvent used in RCF plays a critical role in fractionating and solubilizing the lignin and may significantly impact phenolic monomer/oligomer yields. While methanol is conventionally employed in RCF, the safety concerns and cost issues surrounding the use of methanol indicate the need for green alternatives with lower boiling points to lower the reactor pressure and, thereby, the reactor cost. In addition, compatibility with biological systems is a prerequisite for integrated chemical and biological processes. RCF was explored with ethanol, ethylene glycol, isobutanol, and aqueous mixtures of these solvents, and the lignin monomer/oligomer product yields per kg of biomass and product distributions were analyzed and compared. This research aimed to develop more efficient solvent systems for the RCF of lignocellulosic biomass to maximize the yield of lignin monomers while minimizing process economics and environmental impact.