CHAPTER 3: The Thermochemical Conversion of Biomass into High-Value Products: Microwave Pyrolysis

Thermochemical conversion of biomass appears to be one of the most promising methods by which the knowledge-based biobased economy will develop. With mankind’s insatiable hunger for electricity, chemicals, road transport fuels and aviation fuels showing no signs of abating we need drop-in replacements for coal and crude oil. Through application of microwave heating in place of conventional heating a greater level of control and tunability is possible. Furthermore, microwave processing of biomass offers lower temperatures than flash pyrolysis typically in the order of 200 °C in comparison with >400 °C that will have a significant impact on cost reduction and operational safety. Alternatively, microwave-assisted hydrothermal treatment of biomass offers a different product stream and is particularly effective for biomass with high water content such as food waste. This methodology generates predominately sugars instead of bio-oil, through depolymerisation of cellulose and hemicellulose generating fermentable sugars a wide range of chemicals and fuels can be produced by enzymatic routes.