Computer Simulation of Lignocellulosic Biomass

Transcription

1 Computer Simulation of Lignocellulosic Biomass Loukas Petridis UT/ORNL Center for Molecular Biophysics Oak Ridge National Laboratory

2 Cellulosic Ethanol Production Ligocellulosic Biomass Cellulose Hemicellulose Lignin Pre-treatment Enzymatic Hydrolysis Fermentation 1 Managed by UT-Battelle bottleneck: biomass recalcitrance

3 Physical Origins of Recalcitrance enzymes cellulose lignin hemicellulose pretreatment Collapse of lignin Enzyme:lignin interaction (Structure of lignin aggregates) Lignin:cellulose association 2 Managed by UT-Battelle

4 Petascale Molecular Dynamics Simulation Comparison to Experiments Physical Insights 3 Managed by UT-Battelle

5 Temperature Dependence of Lignin heating 160 C cool-down Old: lignin aggregation during cool-down DOE INCITE New: lignin aggregation during heating 4 Managed by UT-Battelle Petridis et al JACS (2011)

6 Why Does Lignin Collapse at Room Temp? extended ΔG=ΔH-TΔS collapsed Enthalpy ΔH +200 kj/mol Unfavorable Hydration water translational & rotational entropy -TΔS t+r -100 kj/mol Favorable Hydration water compressibility -TΔS fluc -300 kj/mol Favorable Lignin configurational entropy -TΔS conf +10 kj/mol Unfavorable Collapse Driven by Removal of Entropically Unfavorable Water Molecules from Lignin Surface to Bulk 5 Managed by UT-Battelle Petridis et al JACS (2011)

7 Lignin surface is wet at room T, more hydrophobic at high T Hydrophobicity ρ hydr = 0.98ρ bulk lignin dimmer ρ hydr = 0.90ρ bulk 6 Managed by UT-Battelle

8 Biomass Pretreatment Are Lignin Aggregates Spheres? 7 Managed by UT-Battelle

9 r Small-Angle Neutron Scattering I(Q) Q d s 6 Molecular Dynamics Simulation N( r) r d s d s =2.62±0.02 d s =2.65± Managed by UT-Battelle Petridis et al., Phys. Rev. E (2011)

10 Shape of Surface Invariant Under Change of Scale Sim: 1Å Sim&Exp: 10Å Exp: 100Å Surface Morphology Impacts Enzyme Inhibition Enzyme:lignin interaction distribution 9 Managed by UT-Battelle Petridis et al., Phys. Rev. E (2011)

11 Are Lignin Aggregates Solid Spheres? SANS MD rigid sphere Highly folded surface Water penetration Rigid core Fluid surface 10 Managed by UT-Battelle Petridis et al., Phys. Rev. E (2011)

12 DOE INCITE: Lignocellulose Simulation (30M cpu hours) 11 Managed by UT-Battelle

13 Lignin Aggregation & Precipitation on Cellulose 12 Managed by UT-Battelle

14 Interface lignin: crystalline cellulose lignin: noncrystalline non-crystalline cellulose water : crystalline cellulose water : non-crystalline cellulose Interaction Energy Density (kj/mol/nm 2 ) -49±2-50±2-94±2-107±2 Solvent-Driven Preferential Association of Lignin with Crystalline Cellulose 13 Managed by UT-Battelle

15 Multiscale Structure and Dynamics Complexes 1μm 100 nm 10PF (CPU) membranes active site 14 Managed by UT-Battelle 1 nm 0.1 nm Petascale Cluster vibrations 1 fs 1 ps 1 ns 1 μs local diffusion domain motions

16 CPU Strong Scaling Roland Schulz ~ 24M atoms ~1500 atoms/core 24M-atom capability-class simulation of enzyme binding to pretreated lignocellulose 15 Managed by UT-Battelle ~ 100M atoms

17 GPU Scaling Roland Schulz Szilard Pall Berk Hess CPU&GPU 3 years from now (?) CPU 5 years ago 16 Managed by UT-Battelle

18 Outlook Complexes 1μm Exascale living cell 100 nm 10PF Petascale GPU membranes active site 17 Managed by UT-Battelle 1 nm 0.1 nm vibrations 1 fs 1 ps 1 ns 1 μs local diffusion domain motions

19 Acknowledgements Roland Schulz Benjamin Lindner Jeremy Smith Venki Pingali Volker Urban William Heller Hugh O Neill Barbara Evans Paul Langan Brian Davison Marcus Foston Art Ragauskas Funding DOE Office of Biological and Environmental Research Computational Resources National Center for Computational Sciences DOE INCITE award from DOE Office of Science Graphics: T. Splettstoesser and M. Matheson 18 Managed by UT-Battelle