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