Type of Document	Thesis
Author	Robbins, Brett S
URN	etd-04162010-160109
Title	Enzymatic Hydrolysis of Cellulose in NMMO
Degree	Master of Science
Department	Chemical Engineering, Department of
Advisory Committee	Advisor Name Title John Collier Committee Co-Chair Subramanian Ramakrishnan Committee Co-Chair Billie Collier Committee Member John Telotte Committee Member
Keywords	Hydrolysis NMMO Biomass Bioenergy Cellulase Cellulose
Date of Defense	2010-03-31
Availability	unrestricted
Abstract In-situ hydrolysis of de-lignified cellulose pulp dissolved in N-methyl morpholine oxide (NMMO) by commercially available AccelleraseTM1000 was studied under various reaction conditions and reaction schemes. The yield of reducing sugars was followed as a function of time at different cellulose loadings predominantly at an enzyme loading of 122 FPU/g and a temperature of 50oC. A twin screw reactor was successfully set up and used to process high cellulose loading solutions in NMMO, to adjust the pH of the resulting solutions and to run enzymatic hydrolysis reactions. The buffered cellulose-NMMO solutions prepared in the extruder were hydrolysed by AccelleraseTM1000 in different reactor schemes (extruder, shaker bath and stirred tank reactor). A characteristic of all the enzymatic reactions is a sudden burst of sugars due to high initial rates which then levels to a value possibly due to enzyme inactivation. The maximum conversion of the cellulose to sugars is ~ 60% (assuming all glucose) at all cellulose loadings in the extruder. It was observed that a stirred tank reactor resulted in the highest reaction conversions, as well as overall yield of reducing sugars as compared to the shaker bath reactor results. It was also observed that lower initial pH produced improved enzyme activity and higher reducing sugar yield. This study proves the ability of cellulases to perform hydrolysis in NMMO especially at high loadings (13 wt% cellulose in NMMO) to carry out an in situ saccharification of cellulose thus eliminating the need to recover regenerated cellulose as in many pretreatment steps. High yields of sugars (>20 mg/mL in 5 hrs) were achieved in a short period of time by processing of cellulose suspensions with a twin screw reactor for the first time. Thus this work will form the basis for developing a continuous process for conversion of biomass to hydrogen, ethanol and other hydrocarbons.
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