Understanding the impacts of Ammonia Fiber Expansion (AFEX(TM)) pretreatment and densification on densified products quality and the bioproducts yield through enzymatic hydrolysis and fast pyrolysis.

摘要

Lignocellulosic biomass poses significant challenges during handling, transportation, and storage due to its low bulk density. Densification involves conversion of the low bulk density biomass into a highly compacted product which helps in improving the handling, transporting, and storage obstacles associated with biomass logistics. Besides the logistical challenges, the recalcitrant nature of the lignocellulosic biomass makes it even more challenging during the enzymatic hydrolysis. The carbohydrate components, cellulose and hemicellulose are not readily accessible by the enzymes during the hydrolysis process due to the presence of lignin. Pretreatment is the process to convert the native recalcitrant biomass in the form, which is effective to enzymatic hydrolysis. Numerous pretreatment technologies have been extensively studied on different lignocellulosic biomass using physical, chemical, and biological methods. Ammonia Fiber Expansion (AFEX(TM)) is a promising pretreatment method, which involves treating the biomass with liquid ammonia at moderate temperature and pressure. The impacts of AFEX(TM) pretreatment include cellulose decrystallization, hemicellulose hydrolyzation, and lignin depolymerization. Due to these alterations, the cellulose and hemicellulose components can be easily accessed by the enzymes during the hydrolysis step, resulting in increased sugar yields.;To address the logistical issues faced by the large-scale biorefineries, a concept called "Regional biomass processing depots" (RBPD) was developed. RBPDs involve procuring, pretreating, and densifying low density lignocellulosic feedstocks on a distributed scale to minimize the logistical challenges and carbon footprint. To make the RBPDs successful, it is imperative to understand the impacts of different preprocessing operations on the physical qualities of the densified products and the product yields. The increased lignin availability after AFEX(TM) pretreatment helps in better binding of the fibers during the densification process to produce well compacted products. Although, the densification produces compacted products, it is imperative to examine the effects of densification on the biomass conversion process. Hence, this study was designed to study the impacts of AFEX(TM) pretreatment and densification on the densified products quality and the product yields from the densified products. The lignocellulosic biomass corn stover, prairie cord grass, and switchgrass were selected for this research. The objectives of this research are: to understand the compression behavior of the AFEX(TM) pretreated biomass, to study the impacts of AFEX(TM) pretreatment and densification on the physical qualities of the densified products and sugars yields through enzymatic hydrolysis, and to understand the impacts of AFEX(TM) pretreatment and densification on the fast pyrolysis behavior. (Abstract shortened by ProQuest.).