Corn stover pretreatment by inorganic salts and its effects on hemicellulose and cellulose degradation

Inorganic salts, NaCl, KCl, CaCl2, MgCl2. FeCl2, FeSO4, FeCl3, and Fe-2(SO4)(3), were studied as catalysts for the degradation of hemicellulose in corn stover. FeCl3 significantly increased the hemicellulose degradation in aqueous solutions heated between 140 and 200 degrees C with high xylose recovery and low cellulose removal, amounting to similar to 90% and <10%, respectively. Hemicellulose removal increased 11-fold when the corn stover was pretreated with 0.1 M FeCl3 Compared to pretreatment with hot water under otherwise the same conditions, which was also 6-fold greater than pretreatment with dilute sulfuric acid at the same pH. Optimum pretreatment conditions were found where the corn stover was pretreated with 0.1 M FeCl3 at 140 degrees C for 20 min. Under Such conditions, 91% of hemicellulose was removed, and the recovery of monomeric and oligomeric xylose in liquid fraction achieved 89%, meanwhile, only 9% of cellulose was removed. (C) 2009 Elsevier Ltd. All rights reserved.