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Poster Presentation 3-11
Fractionation of Corn Stover by a Two-Stage Percolation Process
Tae Hyun Kim and Y. Y. Lee
Department of Chemical Engineering Auburn University, AL 36849
Telephone: (334) 844-2019; Fax: (334) 844-2063; E-mail: yylee@eng.auburn.edu
Ammonia-recycled percolation (ARP) is a pretreatment method under development in our laboratory. It utilizes aqueous ammonia as the pretreatment reagent and features high degree of delignification. One of the problems associated with this process is that substantial amount of xylan is also removed along with lignin. Since the separated sugars from hemicellulose (primarily xylose oligomers) exist in low concentration in the effluent, it is considered lost in the process. To prevent this loss, we have devised a two-stage process in which an extremely low acid percolation process and the ARP are operated in succession. This process scheme is designed to separate hemicellulose sugars in the first stage and lignin in the second stage. The remaining solid thus contains mostly cellulose. Upon completion of this process, a near complete fractionation of biomass is therefore achieved. Fractionation of biomass can improve the overall biomass conversion technology. Each of the biomass constituents can be utilized with high efficiency since they are recovered in relatively pure form. Early removal of lignin eliminates the interaction between lignin with cellulase enzyme making the enzymatic hydrolysis process more efficient. It also simplifies the down stream processing. The lignin separated in this process is uncontaminated, therefore can be used as a feedstock for further conversion. We have tested this two-stage process using corn stover feedstocks. The effects of process conditions on the compositional changes of the feedstock were investigated. The optimal process conditions that achieve highest degree of fractionation were identified. The enzymatic digestibility tests were performed for the biomass feedstock treated under various conditions and the correlation between the enzyme efficiency and the lignin content were established. Other technical aspects pertinent to development of a two-stage pretreatment process are presented.
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