Ammonia-recycled percolation process for pretreatment of biomass feedstock

AbstractAn ammonia-based biomass pretreatment method named ammonia recycled percolation (ARP) process was investigated. The process characteristics are:1.Aqueous ammonia is used as a pretreatment reagent;2.A packed bed flowthrough-type reactor (percolation reactor) is used in recirculation mode;3.ARP-Ammonia is continuously recycled. The experimental data on hybrid poplar indicate that the ARP is a highly effective pretreatment method. The digestibility of the bestcase ARP sample approached that of filter paper. The extent of delignification in the ARP process was in the range of 23–63%. The ARP process solubilized significant amounts of xylan into the pretreatment effluent, yet left most of the glucan fraction intact. It was demonstrated that pretreatment with pure water at elevated temperatures (autohydrolysis) prior to the ARP selectively removed most of the hemicellulose. A scanning electron microscope (SEM) examination of the solid samples revealed that ARP induces considerable morphological changes reflecting an increase in pore size and porosity. The overall ammonia material balance has shown that in excess of 99% can be recovered.