(738e) Reaction Paths for Hemicellulose Pyrolysis Using Reactive Molecular Dynamics

Using Reactive Molecular Dynamics, elementary-reaction paths are explored and tentatively identified for pyrolysis of xylose, used because xylan is a major part of hemicellulose. Exploitation of conventional fuels for several decades and increase in demand for energy has created a pressing need for biomass to be used as a sustainable, affordable and environmentally friendly source of renewable energy. Xylan, a polymer of xylose (β-D-xylopyranose), is an essential component of lignocellulosic biomass, such as bagasse and corn stover. This study focuses on studying the kinetics of xylan pyrolysis and predicting the products at different temperatures using Reactive Molecular Dynamics simulation, to be compared to xylan pyrolysis data from our group.

Reactive Molecular Dynamics (RMD) simulation is performed on systems of xylose molecules using ReaxFF [Ref. 1] as implemented in LAMMPS [Ref. 2]. This technique simulates the reaction taking place in a system of molecules by considering the energy changes happening in the system due to changes in bonded and non-bonded interactions. Hemicellulose pyrolysis is proposed to occur through pericyclic reactions, based on analyses of cellulose pyrolysis [Ref. 3], in which bond scissions and bond formations occur concertedly within cyclic transition states. RMD simulations allow moment-by-moment observations of these simulated changes. For xylose, reactions were predicted to take place above 500°C. At about 600°C methane, carbon monoxide and water begin to be formed. At 700°C and above, formation is predicted for methanol, methanal (formaldehyde), carbon monoxide, and hydrogen. Additional product and pathway analyses will be presented.

References:

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