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Molecular-level Simulations of Cellulose Dissolution by Steam and SC-CO2 Explosion

Faranak Bazooyar (Institutionen för kemi- och bioteknik)
Göteborg : Chalmers University of Technology, 2014. - 57 s.
[Doktorsavhandling]

Dissolution of cellulose is an important but difficult step in biofuel production from lignocellulosic materials. Steam and supercritical carbon dioxide (SC-CO2) explosion are two effective methods for dissolution of some lignocellulosic materials. Loading and explosion are the major processes of these methods. Studies of these processes were performed using grand canonical Monte Carlo and molecular dynamics simulations at different pressure/ temperature conditions on the crystalline structure of cellulose. The COMPASS force field was used for both methods. The validity of the COMPASS force field for these calculations was confirmed by comparing the energies and structures obtained from this force field with first principles calculations. The structures that were studied are cellobiose (the repeat unit of cellulose), water–cellobiose, water-cellobiose pair and CO2-cellobiose pair systems. The first principles methods were preliminary based on B3LYP density functional theory with and without dispersion correction. A larger disruption of the cellulose crystal structure was seen during loading than that during the explosion process. This was seen by an increased separation of the cellulose chains from the centre of mass of the crystal during the initial stages of the loading, especially for chains in the outer shell of the crystalline structure. The ends of the cellulose crystal showed larger disruption than the central core; this leads to increasing susceptibility to enzymatic attack in these end regions. There was also change from the syn to the anti torsion angle conformations during steam explosion, especially for chains in the outer cellulose shell. Increasing the temperature increased the disruption of the crystalline structure during loading and explosion.

Nyckelord: Molecular modelling, Cellulose, Steam explosion, SC-CO2 explosion



Denna post skapades 2015-03-20. Senast ändrad 2015-03-20.
CPL Pubid: 214093

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik (2005-2014)

Ämnesområden

Kemi

Chalmers infrastruktur

Relaterade publikationer

Inkluderade delarbeten:


Validating empirical force fields for molecular-level simulation of cellulose dissolution


Molecular Modelling of Cellulose Dissolution


Computational studies of water and carbon dioxide interactions with cellobiose


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Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie 3739