Understanding Cellulose Primary Thermo-chemical Reactions to Enhance the Yields of Anhydro-saccharides from Fast Pyrolisis

Washington State University, Pullman WA

Investigators

Abstract

0966419 Garcia-Perez Although biomass fast pyrolysis followed by the hydrotreatment of resulting bio-oils is an efficient approach to convert lignin into green gasoline, the conversion efficiencies of cellulose to valuable products is low. Enhancing the selectivity of cellulose thermo-chemical reactions towards the production of levoglucosan and cellobiosan is critical to increasing the overall efficiency of this technology. The preliminary data obtained suggest that modifying cellulose structure through pre-treatment (formation of active cellulose) in conjunction with a better control of pyrolysis conditions (reduction of pyrolysis temperature and addition of small amount of acids) could be an effective way to enhance the selectivity towards the production of levoglucosan. The major drawback of this approach is that undesirable cross-linking reactions leading to the formation of charcoal might happen if pre-treatment is not well controlled. Furthermore, the presence of lignin seems to inhibit the depolymerization reactions responsible for the formation of anhydrosugars. Previous studies reported in the literature suggest that the inhibitory effect of lignin can be mitigated if small amounts of acids are added to the pyrolysis reactor. Thus the primary goal of this project is to advance understanding of the kinetics of reactions happening during pretreatment (active cellulose formation and cross linking) and of those happening during fast pyrolysis (active cellulose formation, cross linking, depolymerization and fragmentation) and to identify the optimal combination of pretreatment and fast pyrolysis conditions maximizing the yields of levoglucosan and cellobiosan. This project will be carried out in two stages. The first stage will consist of fundamental studies to establish the kinetics of active cellulose formation and cross linking. The kinetic studies will be carried out in a wire mesh reactor. A mathematical model to describe the behavior of pretreatment reactors will be proposed and validated in a continuous auger reactor available at WSU. In the second stage the kinetics of fragmentation and depolymerization reactions will be obtained and these kinetic equations will be used to obtain the optimal pretreatment and pyrolysis conditions to maximize the yield of levoglucosan and cellobiosan. Blends of á-cellulose and lignin will be pretreated and pyrolysed at these conditions and the resulting oils will be fully characterized. This research effort will advance the science required to design new pretreatment and pyrolysis technologies to enhance the production of anhydrosugars from lignocellulosic materials. The PI is building a program at WSU in biomass thermo-chemical conversion which integrates research and education. A new course in "biomass thermo-chemical conversion technologies" is now offered. The new installations planned herein will be used for this course and will be accessible to other research groups. WSU has launched a new initiative for high school students called "Imagine Tomorrow" (http://imagine.wsu.edu/). This project will offer scholarships to some of the winners of this competition to work in the PI's lab during the summers of 2010, 2011 and 2012. A workshop in bio-fuel production will be prepared for high school students attending WSU summer camps. In addition to publishing the outcome of the research in peer reviewed journals and conference proceedings, the results will be disseminated to the public through the WSU Energy Program website (http://www.energy.wsu.edu/).