AMMONIA-RECYCLED PERCOLATION PROCESS FOR PRETREATMENT OF BIOMASS FEEDSTOCK

An ammonia-based biomass pretreatment method named ammonia recycled pe rcolation (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 recircu lation mode; 3. ARP-Ammonia is continuously recycled. The experimental data on hybrid poplar indicate that the ARP is a highly effective pre treatment method. The digestibility of the best-case ARP sample approa ched that of filter paper The extent of delignification in the ARP pro cess was in the range of 23-63%. The ARP process solubilized significa nt amounts of xylan into the pretreatment effluent, yet left most of t he 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 mic roscope (SEM) examination of the solid samples revealed that ARP induc es considerable morphological changes reflecting an increase in pore s ize and porosity. The overall ammonia material balance has shown that in excess of 99% can be recovered.