A packed bed Ammonia Fiber Expansion reactor system for pretreatment of agricultural residues at regional depots

Background: Pretreatment of biomass at regional depots could simplify supply logistics for the emerging biofuels industry. Ammonia Fiber Expansion (AFEX (TM)) could be an appropriate pretreatment method for use at depots, if the process can be simplified. Here we investigate pretreatment of corn stover and wheat straw using a simple packed bed AFEX system that exploits the high porosity of biomass to facilitate ammonia transport. Results & discussion: Steam stripping vertical packed beds allowed recovery of more than 90% residual ammonia as substantially dry vapor. AFEX-treated biomass gave enzyme hydrolysis yields equal to biomass treated in stirred batch reactors, and formed durable pellets. Conclusion: Packed bed AFEX shows significant promise as a biomass pretreatment for use at distributed depots.