Towards Lignin Valorization: Investigation of biological, chemical and hybrid approaches to suppress lignin recondensation and maximize depolymerization
EMSL Project ID
49827
Abstract
The primary goal of this proposed work is to use both experimental and computational approaches to understand and develop an integrated lignin conversion process for better utilization of lignin resources. There has been great interest in and efforts devoted to the conversion of technical lignin (from various current and future industrial processes) into renewable chemicals and fuel additives. A scalable biorefinery that co-utilizes lignin has not been developed yet due to the structural complexity and recalcitrance of lignin, thus limiting full utilization of lignin as a raw material. Moreover, the multifunctional nature of lignin produces multiple product streams, which require extensive separation and purification procedures. More importantly, undesirable reactions such as repolymerization readily occur during lignin depolymerization, which leads to lower product yields and rapid catalyst deactivation as well as condensed products (char) with very little utility. Lignin has a striking ability to self-associate due to the strong electronic stabilization energies between the various intra-subunits, which readily yields undesirable products if lignin is not properly treated. Our preliminary research shows that simple masking of phenolic hydroxyl group significantly reduced the secondary repolymerization, resulting in lower char yield and maximizing lower molecular weight products. Considering that various functional groups are present in lignin structure, the role of each functional group on lignin depolymerization could be different. To increase the economic viability of lignocellulosic biomass conversion, it is important to develop a comprehensive and in-depth mechanistic understanding of the effect of the inherent structural properties on lignin conversion. Additionally, biological conversion of lignin will be studied using evolved lignin-degrading enzymes to understand the potential role of biocatalysts and to develop a combination of chem-bio hybrid strategy for lignin depolymerization and the resultant products profile. In this work, we will explore the effect of structural modification of lignin on reaction chemistry of thermochemical and biological depolymerization. We will leverage EMSL's expertise in spectroscopic techniques such as high resolution MS, NMR and EPR to gain an in-depth understanding of lignin depolymerization. Also, a comprehensive library of analytical data for lignin depolymerization products will be further developed using EMSL's capabilities. In addition, we will conduct computational simulations. In this work, we will utilize a hybrid simulation approach where the environment around the reactive region will be treated using molecular mechanics (MM) description. Together with experimental approaches, these simulations will provide needed insight towards better design of a system for minimizing lignin repolymerization and maximizing depolymerization.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2017-10-01
End Date
2018-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Dutta T, G Papa, E Wang, J Sun, NG Isern, JR Cort, BA Simmons, and S Singh. 2018. "Characterization of lignin streams during bionic liquid-based pretreatment from grass, hardwood and softwood." ACS Sustainable Chemistry & Engineering 6(3):3079-3090. doi:10.1021/acssuschemeng.7b02991
Jian Sun, Dajiang Liu Liu, Robert P Young, Alejandro G. Cruz, Nancy G. Isern, Timo Schuerg, John R. Cort, Blake A. Simmons, Seema Singh. 2018. "Solubilization and Upgrading of High Polyethylene Terephthalate Loadings in a Low-Costing Bifunctional Ionic Liquid. ChemSusChem. DOI: 10.1002/cssc.201701798