Enzymatic Bioprocessing of Cellulose in N-Methyl Morpholine Oxide/Water

To enzymatically convert biomass to biorefinery feedstock, biofuels, or hydrogen an environmentally friendly solvent or process is needed to disrupt the microstructure of lignocellulosics. In multi-stage processes, solvents are being used as pretreatments by dissolving cellulose and precipitation by addition of a non-solvent. We have shown that the processing steps can be reduced by doing the enzymatic hydrolysis in NMMO/H20 which is an industrial solvent for dissolving cellulose. The substrate and commercial cellulase mixture used were dissolving pulp with a degree of polymerization 1160, and AccelleraseTM1000 (Genencor). The enzymes are added to the reactor as the cellulose is coming out of solution thereby hydrolyzing the cellulose to reducing sugars that can be further converted to hydrocarbons and hydrogen. The rates of enzymatic hydrolysis and sugars released were studied as a function of solution conditions- pH, temperature, and enzyme loading. The rates of hydrolysis in NMMO/H20 are initially higher and overall at least comparable to the rates of hydrolysis of regenerated cellulose suspended in aqueous buffer solutions. The results are being used for the design of a twin screw reactor for continuous processing of lignocellulosic biomass.&'