3-76: Optimization of the SPORL Pretreatment of Corn Stover for Ethanol Production

SPORL (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose) is a robust pretreatment technology of lignocellulosic feedstock for cellulosic ethanol production. The pretreatment consists of a short chemical treatment of feedstock with acidic sulfite solution followed by a mechanical size reduction (defiberization). Our preliminary results indicated that the SPORL is a novel and feasible pretreatment technology and meets the criteria for a commercially viable pretreatment process: (1) economical conversion of both the cellulose and hemicellulose to fermentable sugars, (2) low energy consumption in substrate size reduction and surface development, (3) high-value utilization of lignin, (4) mature technology for recovery of pretreatment chemical (sulfite), and (5) low risk in commercialization by using existing infrastructure and mature capital equipment in paper industry.

 In this study, the SPORL process was optimized for corn stover pretreatment for cellulose ethanol production. The pretreatment parameters (chemical charge, temperature, catalyst, reaction time etc.) were optimized through a designed experiment to maximize sugar recovery and enzymatic saccharification. Mass balance of the major components (cellulose, hemicellulose and lignin) of corn stover during the pretreatment was conducted. Enzymatic hydrolysability of the pretreated corn stover and fermentability of hemicellulose-derived sugars in the pretreatment liquor were evaluated. The SPORL was also compared with the dilute acid pretreatment. The results indicated that the SPORL produced more digestible substrate and formed fewer inhibitors to fermentation than the diluted acid pretreatment.