Organosolv fractionation of a lignocellulosic biomass feedstock using a pilot scale microwave-heating reactor

Abstract

Bamboo is among the short-rotation and dedicated energy crops which serve as lignocellulosic feedstock for future bio-refinery. A pilot scale microwave fractionation system (PMFS) was developed and used for the organosolv fractionation of bamboo sawdust. The key component of the system, a 1000 L microwave-heating reactor, was designed with unique features for high efficiency of microwave energy utilization and uniform temperature distribution. More than 800 kg reactant can be heated at 65% energy efficiency with temperature differences between top and bottom reactor positions of less than 4 °C. The operational parameters of the PMFS were investigated, and the fractionation products from the PMFS process were characterized and compared with those obtained from lab scale experiments. Higher lignin (93.2%) and hemicellulose (84.7%) removal rates without serious cellulose degradation (cellulose retention 89.1%) were achieved with the PMFS. Recovered lignin has relatively narrow molecular weight distributions (polydispersity index ≈ 2). The mass balance of the fractionation process showed that 81.5% utilization efficiency of the bamboo feedstock was obtained by organosolv fractionation with the PMFS. The results from this study provide insightful information for the industrial implementation of microwave-assisted thermochemical conversion of lignocellulosic biomass.