Microwave-assisted low-temperature biomass pyrolysis: from mechanistic insights to pilot scale

Abstract

Microwave-assisted pyrolysis is suitable for biomass valorization with the advantages of temperature reduction and energy saving. However, the lack of deep insight into low-temperature behaviors and scale-up demonstration restrict the possibility of industrial applications. The laboratory studies found that the temperature range of rice straw pyrolysis with microwave heating was shifted to 250–300 °C, and the activation energy was about 40–150 kJ mol⁻¹ reduced compared with conventional pyrolysis. The positive promotion of inter-link for the dielectric loss factor of biomass, instantaneous hotspots, temperature and activation energy reduction were revealed. Based on the findings, an original 80 kg h⁻¹ pilot-scale microwave-assisted pyrolysis Auger reactor was designed and continuously operated at 200–300 °C with a 72% net energy ratio. The energy and economic analysis indicated that the small-scale microwave-assisted pyrolysis is suitable for the mobile decentralized biomass conversion system.