CAREER: Revealing Kinetic Pathways by Pulsed-Film Pyrolysis of Cellulosic Biomass

The conversion of lignocellulosic, non-food biomass by combustion, pyrolysis, or gasification provides a sustainable set of technologies for the production of second generation biofuels that can have significant impact on energy independence, economic growth, global emissions, and our society. However, despite intensive research for the past several decades, there is still a lack of fundamental knowledge pertaining to these systems including reaction pathways, intermediates, and detailed kinetics. It is this kind of information that has led to the successful development of the refinery industry in the past century and which is critically needed for biomass utilization. The lack of progress on fundamental understanding of these conversion technologies is partially rooted in the multiphase and multi-scale nature of the raw material and the associated complexity of a large reaction network convoluted with transport effects.

Intellectual Merit: Our objective in this research is to develop the first kinetic description of the individual molecular reactions of cellulose pyrolysis by developing and utilizing a novel experimental technique referred to as ?pulsed-film pyrolysis,? or PFP. The proposed PFP technique aims to rapidly heat micro-scale films of cellulose to 400-600 °C, whereupon isothermal pyrolysis occurs for a defined increment of time (e.g. 10 ms), followed by rapid thermal quench. Kinetic information on the rate of reaction will then be obtained from characterizing the quantity and type of chemical species produced for each consecutive thermal pulse. The research plan

1.) Develop the technique of pulsed-film pyrolysis: Three tasks will focus on designing, constructing, and testing the pulsed-film technique for cellulose pyrolysis. Utilization of multi-physics design models and novel reactor construction will allow for the first experimental system capable of transport-free kinetic experiments at high temperature. is divided into two specific aims:

2.) Measure the kinetics of cellulose pyrolysis: Three tasks will measure rates of formation of primary products (e.g. levoglucosan and furans), secondary reactions of levoglucosan, and condensed-phase reactions to reduce cellulose to reactive oligomers.

At the completion of these two aims, it is anticipated that the kinetics of the major pathways of cellulose pyrolysis will be measured for the first time. Intellectual merit: The proposed research will transform

our understanding of the reaction mechanisms and kinetics of solid and condensed-phase biomass chemistry. A compelling aspect of this research is that it provides the first strategy for experimentally measuring the activation energies associated with the formation of key pyrolysis products, which can be compared with ongoing computations to elucidate for the first time the mechanisms of biomass pyrolysis.

Broader Impact: The scientific discoveries of biomass reaction pathways and kinetics will provide the critical data for constructing first-principles kinetic models which can be used to optimize pyrolysis reactors. Improved biomass processes broadly impact the country by producing higher quality biofuels with lower cost and reduced environmental impact. Additionally, the discoveries and fundamental insights from the proposed research on the pyrolysis of biomass will provide a plethora of opportunities for developing instructive material to educate prospective undergraduates, high school students and the general public on the value and environmental impact of biomass conversion to fuels and chemicals. We propose to develop an integrated strategy with broad impact which combines the education of high school teachers and the instruction of undergraduates to develop presentations for public symposia on the topic of biomass technology, environmental impact and policy. A year-to-year development plan has been proposed for conducting public symposia, which will be broadcast on the internet along with educational materials for broad dissemination. Integrated with the symposia will be an undergraduate course focused on renewable energy as well as an NSF-RET proposal for hosting science teachers and developing learning modules for K-12 students in schools with high concentration of underrepresented minorities (Springfield, MA, & Milwaukee, WI). Our approach to education will contribute to ensuring that students from economically depressed backgrounds and underrepresented minorities have access to inspiring examples of engineering science and technology and that the general public is well-informed on the importance of biomass conversion as a sustainable and environmentally-friendly means of achieving the national goal of independence from imported oil.