(474e) Uncertainty Quantification of the Water-Gas Shift Reaction By Pt/CeO2 Catalyst

Uncertainty Quantification of the Water-Gas Shift
Reaction by Pt/CeO₂ Catalyst

Eric Walker¹,
Gabriel A. Terejanu^2,*, Salai Cheettu Ammal¹, Andreas
Heyden^1,*

¹Department
of Chemical Engineering, University of South Carolina, 301 Main Street,

Columbia, South
Carolina 29208, USA

²Department
of Computer Science and Engineering, University of North Carolina at Charlotte,
Woodward Hall, Charlotte, North Carolina, 28262, USA

Theory and experimental data are
incorporated in a multiscale modeling framework to determine the catalytic
active site of reaction. This computational framework includes uncertainty
quantification arising from theory and the model’s discrepancy with
experiments. Two active sites and their corresponding models are inferred from
three sets of published experimental kinetic data. An interfacial active site
model and Pt-only active site model, both with multiple reaction mechanisms in
the model, are compared. Figure 1 displays an example inference for the
interface site. The interfacial site is consistently the active site for the
temperature range studied 473 – 573 (K). Separate reaction pathways are
competitively active within the interfacial site. The dominant pathway shifts
depending on a key rate-controlling step at the initiating juncture of the
pathways. In constructing the prior Density Functional Theory (DFT)
uncertainty, the Hubbard U parameter was evaluated at 2, 4 and 5 (eV). In
addition, the energy of the states was computed with Heyd-Scuseria-Ernzerhof¹
functional. The inference provides information about the relative accuracy of
these functional inputs.

Figure 1. Inference of the DFT
uncertainty for the Pt/CeO₂ active site. Reaction corresponds to
Heyden, et al.²

[1] Heyd, J.; Scuseria, G. E.; Ernzerhof, M. Hybrid
Functionals Based on a Screened Coulomb Potential. J. Chem. Phys. 2003,
118 8207.

[2] Aranifard, S.; Ammal, S. C.; Heyden, A. On the
Importance of Metal-Oxide Interface Sites for the Water-Gas Shift Reaction over
Pt/CeO₂ Catalysts. J. Catal, 2014, 309
314-324.