Temporal Resolution in Fast Pyrolysis of Lignocellulosic Biomass

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Principal Investigator: Young-Jin LeeNumber: 1438004Biomass from plants is a feedstock for the production of biofuels. One route for processing plant biomass into liquid transportation fuels is to rapidly heat up the solid biomass material in the absence of air, a process called pyrolysis. Pyrolysis initiaties a series of complicated decomposition reactions to produce a complex mixture of liquid hydrocarbons, gases, and carbon-rich char. This research project will use a novel apparatus to study the complicated reactions of pyrolysis in real time and measure pyrolysis products very accurately at reaction times of under one second. From this fundamental information, detailed reaction models will be developed, which can be used to improve the performance of pyrolysis processes to produce liquid hydrocarbon fuels, guide chemical reactor design and scale-up, and accellerate process development leading to commercialization. Education and broadening participation activities provided through this project feature a summer academy for middle school science teachers on the subject of biorenewables and the bioeconomy.Technical DescriptionPyrolysis is a process for conversion of biomass to a complex mixture of hydrocarbon liquids, gases, and carbon-rich char where solid biomass material is rapidly heated in the absence of air to initiate a series of thermal decomposition reactions. The goal of this project is to study the product distribution in fast pyrolysis of lignocellulosic biomass in real time. This research will be enabled by a unique micro reactor where a fast-scanning, high-resolution mass spectrometer is attached to a drop-tube micro-furnace pyrolyzer. This configuration is capable of monitoring the fate of each molecular product with sub-second temporal resolution. The research will characterize the molecular kinetics for fast pyrolysis of glucose-based carbohydrates, investigate molten phase and conduction effect in cellulose pyrolysis, and explore lignin pyrolysis in high temporal resolution. It is hypothesized that cellulose pyrolysis occurs in two distinct time steps, one narrow-time profile and one broad profile, which are attributed to solid surface pyrolysis and molten phase pyrolysis, respectively. The pure reaction kinetics of cellulose and lignin pyrolysis on extremely thin film where molten phase reaction is can be ignored will be investigated. Details of elementary chemical reactions in cellulose pyrolysis will be further explored by systematically studying the pyrolysis of glucose-based carbohydrates for various chain lengths and glycosidic bondage types. A wide range of film thicknesses will be studied in order to monitor the transition from isothermal kinetics to conduction-limited kinetics. This will also reveal how molten phase pyrolysis is influenced by sample size and how it contributes to the final product distributions.Education and broadening participation activities provided through this project feature a summer academy for middle school science teachers on the subject of biorenewables and the bioeconomy, sponsored by the NSF Engineering Research Center for Biorenewable Chemicals (CBiRC) and the NSF EPSCoR program at Iowa State University. This project will support and closely collaborate with one of the participating teachers in the preparation of classroom materials about bio-oils. College and high school students will be exposed to the biorenewables technology through this project, including under-represented minority students in Science Bound program.