Microwave-Coupled Liquefaction of Lignocellulose: From System Synergy to Continuous Flow Process

Microwave-assisted hydrothermal liquefaction (MA-HTL) is increasingly recognized as an innovative biorefining process. It converts a diverse array of biomass feedstocks into valuable products. To date, the majority of research has primarily concentrated on the liquefaction reaction within small batch reactor, systematically screening processing parameters to maximize product yield. However, the understanding of the specific interactions between microwave and liquefaction processes remains constrained. Furthermore, it is essential to explore the advantages that promote the scale-up of MA-HTL reactors for industrial applications, particularly in light of the unique characteristics associated with microwave technology. This review aims to systematically compile and elucidate the existing research on microwave-medium interactions in liquefaction systems, highlighting the critical relationships involved in microwave field and reaction system. An overview of both microwave batch and continuous flow reactors is provided by the microwave and liquefaction processes on reactor design. Based on the recent technological advances, the future directions for the development of MA-HTL technologies are predicted.