A Novel Extractive Ammonia Fiber Expansion (AFEX) Process

Michigan State University has developed a novel lignocellulosic biomass pretreatment process that results in the formation of highly digestible cellulose III allomorph. The method also provides the option to simultaneously extract biologically inhibitory cell-wall extracts such as lignin, lignin decomposition products, xylo-oligosaccharides, and amides using essentially anhydrous liquid ammonia pretreatment (ALAP). This is important because cellulose crystallinity, lignin-carbohydrate complex (LCC) ester linkages, and non-specific enzymes binding to cell wall components (like lignin) are the major rate-limiting steps to efficient cell wall deconstruction. Non-crystalline cellulose (known as amorphous cellulose) has a four-to-five-times higher rate of enzymatic hydrolysis than native crystalline cellulose. More readily digestible product: The ALAP process produces amorphous cellulose, which is considered a more highly digestible form of cellulose than native cellulose I. Flexibility: Two streams are created by the process: one rich in cellulose and the other in hemicellulose-lignin. Each stream has the potential to be used to produce different products.