A Review of Microwave Assisted Liquefaction of Lignin in Hydrogen Donor Solvents: Effect of Solvents and Catalysts

Abstract

Lignin, a renewable source of aromatic chemicals in nature, has attracted increasing attention due to its structure and application prospect. Catalytic solvolysis has developed as a promising method for the production of value-added products from lignin. The liquefaction process is closely associated with heating methods, catalysts and solvents. Microwave assisted lignin liquefaction in hydrogen donor solvent with the presence of catalysts has been confirmed to be effective to promote the production of liquid fuels or fine chemicals. A great number of researchers should be greatly appreciated on account of their contributions on the progress of microwave technology in lignin liquefaction. In this study, microwave assisted liquefaction of lignin in a hydrogen donor solvent is extensively overviewed, concerning the effect of different solvents and catalysts. This review concludes that microwave assisted liquefaction is a promising technology for the valorization of lignin, which could reduce the reaction time, decrease the reaction temperature, and finally fulfill the utilization of lignin in a relatively mild condition. In the future, heterogeneous catalysts with high catalytic activity and stability need to be prepared to achieve the need for large-scale production of high-quality fuels and value-added chemicals from lignin.

Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

“…Regarding the latter, biomass is currently the world's fourth energy source (about 10-14%) after conventional fossil oil, coal and natural gas. 4,7,8 Therefore, knowing the finite nature of these fossil energy carriers, the International Energy Agency (IEA) estimates that almost half of the energy demand by 2050 should be produced from biomass. 9 Thus, over the past few decades, there has been a tremendous amount of work being done in the area of biomass valorisation to produce valuable products (biochemicals and biomaterials) and energy (biofuels).…”

Electrochemical Routes for the Valorization of Biomass-Derived Feedstocks: From Chemistry to Application

“…Over the past few decades, approaches to valorize lignin have included microbial-enzymatic, thermochemical (including pyrolysis, hydrothermal, microwave-assisted methods, , etc. ), photochemical, , electrochemical, ,,,− and electrochemical photoredox .…”

“…In this context, many works have outlined different thermochemical and biochemical approaches for lignin valorization; − , however, just in 2018, a review about lignin ECOD was published by Zirbes and Waldvogel . Therefore, in this section, we will present only the main advances of this field published over the past 5 years as well as some novel methodologies that were not cited in that mentioned review, summarizing key information about these works in Table .…”

Temperature distribution of SiC bed surface in a large-scale microwave-assisted pyrolysis reactor

“…Microwave heating has the advantages of high heating rate, ease of start-up and shut-down, and low thermal inertia. Therefore, it is widely used in biomass treatment and conversion such as drying, roasting, pyrolysis, gasification and carbonization [1][2][3][4][5]. However, few studies on industrial scale microwave device for biomass conversion were reported [6][7][8].…”