Overview of Multiscale Modeling Approach
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Transcript of Overview of Multiscale Modeling Approach
Catalysis Center for Energy Innovation
Overview of Multiscale Modeling Approach
Dion VlachosUniv. of Delaware
Catalysis Center for Energy Innovation
Mathematical and computational methods developed
Bottom-up modelingProcess design
Coarse-grainingTop-down modelingCatalyst design
Bottom-up and Top-down Modeling:Process Design and Catalyst Screening
Reviews: Chem. Eng. J. 90, 3 (2002); Chem. Eng. Sci. 59, 5559 (2004); Adv. Chem. Eng. 30, 1 (2005)
Catalysis Center for Energy Innovation
The 30,000 Miles AirviewSignificant progress made on method development and testing
Field is maturing
Focus has been on prototype problems
Complex systems have by-and-large not been studied
Perspecive: Vlachos, AIChE J. 58(5), 1314 (2012)
Catalysis Center for Energy Innovation
Hierarchy Enables Rapid Screening of Chemistry, Fuels, and Catalysts
Quantum:ab initio, DFT, TST,
CPMD, QM/MM MD
Continuum: MF-ODEs
Discrete: KMC
Ideal: PFR, CSTR, etc.
Computational Fluid Dynamics
(CFD)
Length
Mesoscopic:PDEs
Discrete:CG-KMC
Pseudo-homogeneous:Transport correlations
Quantum-based correlations:
BEPs, GA, LSRs
Catalyst scale:Reaction rate
Reactor scale:Performance
Electronic scale:Parameter estimation
Accuracy, cost
Review: Salciccioli et al., Chem. Eng. Sci. 66, 4319 (2011)
Catalysis Center for Energy Innovation
Toward High-throughput Computing:Metal and Metal-like Catalysis
Thermochemistry via GA & LSRsReaction barriers and pre-exps via BEPsPerform MKM
DFT-based, semi-empirical, or hierarchical (screen with semi-empirical and refine via DFT)
Error analysis; Assessment of model predictions
Brønsted Evans Polanyi (BEP)
Microkinetic Model(MKM)
Salciccioli et al., J. Phys. Chem. C , 114, 20155 (2010); J. Phys. Chem. C, 116, 1873 (2012)Sutton and Vlachos, ACS Catal. 2, 1624 (2012); J. Catal. 297, 202 (2013)
Linear Scaling Relations (LSRs)
Group Additivity (GA)
Catalysis Center for Energy Innovation
• Instead of simulating dynamics, KMC focuses on rare events• Simulates reactions much faster than Molecular Dynamics• Incorporates spatial information contrary to micro-kinetic models
The Kinetic Monte Carlo Approach
CO(gas) + OH COOH
reactants
products
Potential Energy Surface
Metal surface
transitionstate
‡
B
E‡k TB
rxnrxn
k T Qk eh Q
Stamatakis and Vlachos, J. Chem. Phys. 134, 214115 (2011); http://www.dion.che.udel.edu/downloads.php