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

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 degrees 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 approximate to 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.

Automated summary

A pilot scale microwave fractionation system (PMFS) was developed for the organosolv fractionation of bamboo sawdust. The PMFS achieved higher lignin and hemicellulose removal rates without serious cellulose degradation. The recovered lignin had a relatively narrow molecular weight distribution and the process showed good utilization efficiency of the bamboo feedstock.