Unraveling Electrochemical Lignin Degradation in Organic Solvent for Production of Valuable Fuels and Chemicals

Abstract

Lignin is the second most abundant biopolymer in nature after cellulose. Due to its distinctive aromatic backbone, it is also one of the most unique biopolymers. The aromatic components in lignin provide structural support to plants and comprises about 30% of the plant material. These aromatic groups can be used to produce renewable aromatic compounds. Also, these aromatic compounds can be used to produce biofuels which can be promising alternative to fossil-based fuels and chemicals. Besides, from previous studies it is found that about 40 to 60 million tons of lignin are generated from pulp and paper industry, mostly as wastes. So, developing novel and attractive strategies for fragmentation of lignin is gaining increased interest among scientific community for valorizing this underexploited material. Also, by valorizing lignin the sustainability of biorefinery and paper industry can be enhanced. However, the present technologies used for degradation of lignin generally requires the use of metallic catalysts at high temperatures and harsh reaction conditions. As a result, catalyst recovery and decomposition often become difficult under such harsh conditions and the process becomes impractical. Also, these technologies suffer from poor selectivity and usually produce the desired fragmentation products in low yields. Compared to the thermocatalytic transformation of lignin, electrocatalytic approaches have several advantages like it is environmentally friendly, have mild reaction conditions and the cost is low. Besides, there is a lack of studies incorporating electrocatalytic oxidation and reduction of lignin in organic solvent. In this project, the main goal was to overcome the challenge of using isolated lignin from various industrial processes by electrochemical depolymerization of lignin in organic solvent like tetrahydrofuran. Tetrahydrofuran is mainly used in Co-solvent Enhanced Lignocellulosic Fractionation (CELF) process. So, electrocatalytic degradation of lignin in this solvent is beneficial because the product from CELF process can be directly used here and thus it can work as a secondary treatment process for CELF process. Cyclic voltammetry (CV) and Chronoamperometry (CA) which are important tools for identifying redox reactions happening in the system is used here. In this presentation, for varying concentrations of Lignin, Tetrahydrofuran and sulfuric acid the results found from CV and CA will be discussed with practical significance.Keywords: Recalcitrant biopolymer, Lignin in organic solvent, controlled electrocatalysis, secondary treatment for CELF process, Cyclic Voltammetry