Microwave-assisted processes for biomass valorisation

• Main Author: Li, Tianzong
• Other Authors: Clark, James ; Budarin, Vitaliy
• Published: University of York 2017
• Subjects: 540
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.731582

Lignocellulosic biomass and its major organic components are widely recognised as a renewable resource to produce energy and chemicals. The process imbues the principles of green chemistry and sustainability; therefore, interest in the valorisation of lignocellulosic biomass has significantly increased. Microwave heating has been proven to be an effective, alternative heating method for the pretreatment and conversion of biomass. Herein, different routes for the valorisation of lignocellulosic biomass and its major organic components, such as bamboo, beechwood xylan, and starch, using a microwave as the heating source are reported. Microwave-assisted pressurised, additive-free, and low-temperature (< 250 °C) pyrolysis was conducted on beechwood xylan using both a constant microwave power and reaction volume, with various degrees of beechwood xylan loading. This allowed for analyses of how and to what extent the reaction pressure and the presence of pyrolysis decomposition products affected the efficiency and product selectivity of the microwave heating process. Due to the different physical states of the volatiles that are released during pyrolysis and that are dependent on the pressure attained, it was demonstrated that xylan loading had a significant effect on the distribution of the final products. Microwave-assisted organosolv experiments were performed on bamboo powders using a fractionation approach. The effects of reaction temperature, solvent composition, and catalyst loading on the organosolv process were evaluated by statistical methods, to determine the effects of operating variables and optimizing the process towards a selective fractionation. Moreover, the direct application of organosolv lignin as an additive for sunscreen was briefly tested. A novel mesoporous material, Starbon®, was produced from starch by expansion, retrogradation, and carbonisation approach. By introducing microwave-assisted heating to the starch expansion process, the total production time was significantly reduced, resulting in a more energy-efficient process.