Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production

Abstract

Lignin valorization is essential for biorefineries to produce fuels and chemicals for a sustainable future. Today's biorefineries pursue profitable value propositions for cellulose and hemicellulose; however, lignin is typically used mainly for its thermal energy value. To enhance the profit potential for biorefineries, lignin valorization would be a necessary practice. Lignin valorization is greatly advantaged when biomass carbon is retained in the fuel and chemical products and when energy quality is enhanced by electrochemical upgrading. Though lignin upgrading and valorization are very desirable in principle, many barriers involved in lignin pretreatment, extraction, and depolymerization must be overcome to unlock its full potential. This Review addresses the electrochemical transformation of various lignins with the aim of gaining a better understanding of many of the barriers that currently exist in such technologies. These studies give insight into electrochemical lignin depolymerization and upgrading to value‐added commodities with the end goal of achieving a global low‐carbon circular economy.

Exploiting Nature's Most Abundant Polymers: Developing New Pathways for the Conversion of Cellulose, Hemicellulose, Lignin and Chitin into Platform Molecules (and Beyond)

“…It is thought likely to contribute to second and perhaps even third generation biorefineries. Electrocatalytic, photocatalytic and microwave techniques for processing lignin are also garnering attention [48c,o,x] …”

Green and sustainable route for oxidative depolymerization of lignin: New platform for fine chemicals and fuels

“…Recently, the greener-and electrochemical-based catalytic oxidative valorization of lignin/lignin mimics under environmentally friendly routes is extensively reviewed. 42,43 The electrocatalytic oxidation would-be an alternative and a greener way of lignin depolymerization The future work in this area of electro-catalytic oxidation need concentration on the development of electrocatalysts with high activity, stability to the applied potential and should be cost-effective for lignin oxidation. In addition to electrocatalytic methods, photocatalytic methods also do offer valorization of lignin motifs as discussed below.…”

A Divergent Paired Electrochemical Process for the Conversion of Furfural Using a Divided‐Cell Flow Microreactor

“…Notably, electrochemistry allows to convert green electricity, derived from wind and solar energy, directly into useful chemicals, and kinetic barriers are overcome by applying a suitable potential over the electrodes. Hence, no additional reagents are required to enable reduction [11–14] and oxidation processes, [15] which can aid to further reduce fossil fuel consumption (e. g., hydrogen is often derived from natural gas via the water‐gas shift reaction) [16] …”

“…Hence, no additional reagents are required to enable reduction [11][12][13][14] and oxidation processes, [15] which can aid to further reduce fossil fuel consumption (e. g., hydrogen is often derived from natural gas via the water-gas shift reaction). [16] While several useful electrochemical strategies for the conversion of furfural have been developed, the focus so far was almost exclusively on the optimization of a single electrode reaction. However, when both electrode reactions are harmonized to produce value-added products, a green and sustainable synthesis can be obtained, which maximizes productive use of electricity, minimizes waste generation, and reduces energy consumption.…”