Fractionation of Herbaceous Biomass by Ammonia-Hydrogen Peroxide Percolation Treatment

Abstract

Treatment with ammonia and hydrogen peroxide was investigated as a means of fractionating herbaceous biomass. The main feature of this process is that aqueous forms of these reagents are pumped simultaneously into a packed-bed flow-through-type reactor (percolation reactor) under a semibatch mode with ammonia being recycled. Experimental tests on corn cobs/ stover mixture (CCSM) and switchgrass feedstocks have proven that a high degree of fractionation of biomass into three major components is attainable under this process scheme. The extent of delignification was 94–99% It was achieved at a representative condition of 170°C, 0.28 g loading of H₂O₂/g biomass, and 10 wt% ammonia concentration. At the same time, about 80% of total hemicellulose in the biomass was separated out into the effluent primarily in the form of xylose oligomers. Decomposition of sugar components was insignificant. The remaining solids had a composition of 80–93% glucan, 5–10% xylan, and 1–6% lignin. Selected solid samples. obtained under near-optimum conditions, exhibited a chemical composition close to that of commercial a-cellulose The enzymatic digestibilities of these solid samples were substantially higher than that of α-cellulose.

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